J I A Reproduced Copy Reproduced for N,ASA by the NASA Scientific and Technical Information Facility 111111111111111111111111111111111111111111111 NF01466 FFNo 672 AuSl 6S https://ntrs.nasa.gov/search.jsp?R=19840013809 2020-03-21T00:01:32+00:00Z BEST AVAILABLE COpy All Missing Pages IMissing in Original IDocumelnt " ,.' ''''.''.e'·'·~ -.rae' 0, (h" nL, u~( '~I'I. -I', \ :. ,', 1-' .. 'is- to provi' . . . pOSSI~ contained in , c •• ",._ • ..~ _ • ment f the ral, ti< IS ita ....--...-- " 'i!(' ,5' ·:.. ,~..; ., . • f 1 I'ROCEIEDI . a TWE H CONF-821055-- DEBl 016840 fiVE TECH ..... lOGY MJENT G TR TORS' 11~AT MEETING P-120 ~by: u.s. D~Ml1>~ EfI~ ~ of "tShlcta In.d Er"~ift!l R&D ~tftlW'~ ~~E~ Publm~by: ~-v @f AWl~E~~ 800. _~t.(Mw . WM~.PA.15_ Aid'. J NOTICE This ftlptllJt Wti5 ~ as 16'1 ~t of WOII'Ik ~ by tha Uni1i2d ~ ~mm&mt. tWhll" tiwUnitedSttitea nor tiM! um~ SW:~ ~"i.n'm\t of ~. ncM" any of th@\1I' emp~;llQS. m_m lIfti\' ~1j. ClMi~ or ~. W' ."''if!'iElS my ~ 1~!1ty or ~bmtV fer tM IIIIltU- mev. c:~~. or uoofulnmi of fIIfIY Information. appe- rews.. ~u:ct. or ~ ~CImf .. or ~ that Its I.m wootd not ifI~ ~~ ~ ~. Re~ ~n to &ny ~dfk; CGi~ pJ~ rms-. or.-· vk.le bJ¥ t.Rd!l n!llm&. am!iI'fc. "~. or Glb~." not ~Iy ~UI wlmptv iU~1IW. ~ ~~~Wm.o:rf~f'.ebv ttllll ~ __ G~or aRlV 3!l~"V 1Ai~. Tiw ~ .. ~ at' ~ex ~ ~ln d\) not: fit 7!iJmlfity "'': or ~ttG&oftile Urll~ ~~ Gci'tli ~I ~ ~ PW'~ ~ ~ll. M~. Co. Naif'" F~.ll}ytvMm '_1& .. ~ I J TABLE Of CONTENTS 1I\'OjJ'III1f.f» ~., Albert A. Otesnes • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • An OwMtmoftht u.s. ~'t.~ell r~.lWt~ ~E~ y_~ hm~ Pt"'~. htJiek L Suttm'! •••••••••••••••••••••••••••••••••• 3 "" 1M 4~ Som Still~ E~A~" ~. Sten Ho\p'sson and Wort', H. ~I •••••••••••••••••••••••••••••••••••••••••.•••••••••••••••• MIlr.·JIl~~tiG!lt~~!1_~1 ~f~~of~mg E~ T~I~. P. D. FairchlklaM C. D. ~ •••••••••••••••••••••••••••••••••••• BtMkliJ E~l1iiuw Appr~~. W.I~Tesg~ end David R~ CuM~ •••..•.•...•....••• ~m~~riW:l!D~~~~_~R~ Nolll P. Niahtin~ •••••••• ~ .••••••••••••••••••••••••••••••••••••••••••••••. ~mothl'iil Stiri~tt E~ Dd~.t Pt,@,,#w."<-~ I Sth_ FE ... ~~ '~fmmGe. AfufJI't Rin't' .................•...•........................ ~,,,~ MM I Stjriq ~ ~.~ I-A). fre~-01nl ~ •••.••••••••••••••••••• ~ilCl'OO1i\>1a SitkliJl!I E~ h~lq ~,~ E~ CMW-,.MM!;.HIII~ E$;!l.m G3 ~tm. Ror;ar A. F~I ............................. . tJl.n)mOi,hI9 S>lirlWlIfj EttiliWd@ ~\'l!.rt ~~,,*Sl1tlr~~ E~ ~ fUlll.s Tm RlO$!.i!!ti, R~t A. Battlttn ..•..•.•.••....•••..•••••••••..•..•••••..••. Sajij'ling E~i1l(l) Mil1t0,iil!$ RiW,"~ lilt NASA lJ.w:i1E. ftPJTB, &mIJ U$AB • .Iostl\!lh R. Steptien!l. Michl!l.ll T. OtNIin, and Erik s.~0® ••...•..••••••••.••••.•••••••••.••••••••• F,_~ OOdUrl1ll Hv~~ ~ fGi' ~~ll/lJ. OMeld G. Beremand, J!tck G. SlcllIv. ·and Dtwid Miro •.••••••••••••••••••••••••••••••••••••••••••••••• A LClMllk 8t II ~id, Iflw!at§d ~ I:~. William ~ •• Tamale ••••••••••••••••••••••••••• A~ Goo Tuubi~ T~inW::@iW ~\1\I~1~ (!~~m IfflI!Jl ~!~},. R. A. Rlilcld*V and D. M. KreiMf • • • • • • • • • • • • • • • • • • • • • • • • • • • • • .. • • • • • • • . • • • • • • . • •• M1lM~ GM TUlrmoo T~ nm'~:I om 5i~at~. J. R. Ntmiboo'l. S. 1\. NtM'riS-JomI'lIl, and B. M. ~ •••.••••.•••••••••••••••• 317 F.~W!m:oefE~.~~M~~~fud~. J. So. Ctlill, I!.\"iill A. H. i.AIfl,"bl.'f0 •••••••••••••••••••••••••••••••••••••••••••••••••• 325 ~~klfj~ lE~of~Al~'t'fi ~.NeImlM R.~_ • .ItJhn It.. ItU5S1l!li. ThtlmM W. nym, m. llfid Tiroothv j. CdllNn ••••••••••••••••••••••••••• m $!Jm.~: F~~ 01 ~-t,.r~ $II Et~ R~~a~. Robilrt R. htt • .If., Micl.oo! It S'wiill'l, ood .klitn M .. iI'~ • . • • . • • • • • • • • • • • • • • • • • • • • • • . . • • • • . • • • • • . . •• 3>t9 G®!If4Jl.!.l$ Fw~ ~~ ~!m1l-$~j{l Rf~ M. C. K~I&.. F. J. E~l'V. J. R. Baflliit. and te. D. Willlen'OOl"I •• k. • ............................................. _ ~($;!iMf~ I~~-m 01 ~ ~ l~ Srwl~ ~'&liu E~. L. H. UI'(IlMnlril/i, J. F. N~Ufi. Md ft K. PefWr;l •••••••••••••• , ••.•.••.••••••••••••••• 361 f.!!1WiI~1i~ u1 ~ ~U~\Fili0 ~ fi'fi-~~~~ mlll fi'-viEIJ ~~ ~U!.WW r'M~?,jlf~1 wM~ M.l!lG~~'..e_a,ll$ &l.W&. C. F. ROOri~7l1lll'!d J. P. CI?OlI~~. Jr. • ...........•......•...•........•..•.•.....•.•......•...••• m tJi)' Good rooming IaIdiH end Clmtlem.Jft-Mid ~to the T~~ T~ Oem- ~'t~' CoofdlMtfon~. k Imln~ In your ~.lMI, the ConiivfiN» tiab PIW wi! ~, some new fiNIbns. FJnt of .... thmlwl!i be no ~ -wOM. Qmi1lU'mlnt .... WIN tMl'M6tw ~amt .... Md from fonmtIr etm~ attmdlw-s, end G'IIefY effmt hasb!!m madIt.~ JI9'OIfI!M acthllthluocon- Clemnt ~ wme not roquiRld. Wilt ~ aho~. 8ft ~Oft'OI!.fl!lId tho tndt.!Jitry ~ SMol, on W~ aftlamOOfi. ~ Itt dm of _ eng!nt twdInoIOfW ~ t!om,'lhl$ ~ fJ W8$ $31.7 ~. with $33.6 miftfCllil promr~ for II\!hl~ ,",,"lf~ .Mid 84.2 million fer ~.~ In ~ to In CI'm'IIII ret- di!..!ctior; In ~t. tM JW~~l!lffl W$'j ~G nrl'~ in FY ,m, Pa CJl!!ft of the ~ Enefmv PoUcy ~mn of 1~ji. 1M I~m~"l'lt ~G ~,jfl v.i!~'M1f~ Of ~~ ~ ftomPfClWImI VlItim~ !ltl'f~&:W1t!1t ~t iI~ti~ tm~ to ~~ _~ .. Our ~. ret- orbntl:!~i;.)11 fi'~ from COOIlJ'i«Nti®!il'3tlM, _~08j. (II' .,.Iu ~ ~ dvffim. amt ~;'IOOflltfDf-of~t ty~~ ~fJ'~fmIt filJdw tm.n flInt ~ ~, em h4'1t-MIc hljzh-p.l!V(lH l()!flV"W'1'Il tsdmolO!f'l 001rl(11'$ Vl.tw.ro tilQ hlCh rWctt tftwot_ prohibit IncNstry "rPnt it mo.'l't", MOd (!lit ~lQrie ~~11:h ",~!d1 t ... ~ ti'l@ ~ fw~t~~ Thal r0'rmt!®l~ hslJ ~ I~ em 0f1ll' F\' 1m uti~ Ml\lI!Iw·mm~t ordsmcn- stm:ion Jm1Il!4:tJl WG-d S'tirHni.i qn& ~Ul \IVl:W ~_ froB. fId (maiM sy&tem typ9 ~ to II proof'(lf"c&"t\,)io~ IItfucM{.l ,~ fa> ... w er1~ ~ tWo ~md. _ ~ of ~we hi ~Iletl by dlf$l<·tmtlm..tP.tf4i'~~"~t; of tmll~~ ,...~ ~ for.thHt of ~ s/bUIlV in ~ wdI~ a IKll.W~ d>~~t.. \lr.t~ ~~n. end fiMl ~ ~~ to in4'ulltfV. wi~ !filAA)nvmmt·~ fum.tl~n lif~~ til ~. of ~I$ bs!lk: ~ 1"* tIlMft 1$ In Ii .. e willl'i tiw G'~I er~:tt on ~,~,w;wti~2cri~ ~iij'~ 1~.1!!td h ~ ~tl!'Mion on fUl'lltli~l'l®l'a~ t@~fm~j,e;1>I bml9 FV 19ms9~fllNllllt~fIln'M$t\Illt~. prniclJlariy in the aln~1I of ~~ dMty Ua\lll1if,;.'1}i'\ ~~tII'1 ~mI'tt. to Pf~ W'~ ~ imof,.. IMnt not m~v in th!l t(1~~ltil~J'j of mcl~i'J~ fJ!Il\rb(~ lm!11l in ~.r l~im.tifi~)t1M _ cNr~:lMicm. Major FY 19\~ fJl':'ti".ltis~ WM1} O'Jil'ItlOllOO irl fOUf arem. In _ ~l«II!1l;'e 1M b~ lift' the tint build aM (Mi2Iimil'l/M1f Wl'l'Jittil:f>",~ o~ ll4oo8'it)f'&1jfll©@~ ~ ~ ~. MN ~ by both ~ ~ bl\WJt't~ I~ ~~ pY~~iJm. In puWl!~4\~.fl~ll.Um!~lIffwtcm~ltGf~~ o!lM m.~llii'ri. tsd'm'J>iolW \'~iI e'i'ti-nM ~~'t, In tilt! ~&~~~l/0ietl:~'l\f fpdkd out In 1he f~. l'hIJtu VI1m no SIIdt ~ In WI!' ~ AOO ~, ~t) 1m! 'to 00 00 sI~lfk:lMt ~I'IS In ~YMOOt ~ bekmr ~ 1111 effm em 913@1B2. The ~utioo ~wtEv I't.'!il5wd·~ 11. ,. ~I' ths~ tk.'tl tMlt 1M ~~ ~il:4:Wll'i ~H wHl be t~ by milt dtae. Whllt caWI Ifro ~!!~ during I=Y 1~? It is cl@.ar that ~ will be. 4xmtinulnt focw on Ioog-term. hilllHlfltc. pm~i'I!:ialty hiW!-P.t~ refumct 00 the I)rise ar.e-3!1 include: ioTbls c"erview is M!i:.ed em the o1\'4l11i~ r~l!'ks of thll a",toor ali, 11lader of tile S1:1r111\8 ei'![,ln'1l _"'!)lion of the 1932 AutOlllOtive YIlCtumlGg)' Dev@lopwnt/Ccmt.rlACton' Coor4iftlltion NeetillS_ Oc:tobelr 25-28. 1982. in Dearborn. Kichigan. Patridt L. Sutton u.s. Otlpartment of Enorgy Washington, DC the MOD I engi.ne; power and efficiency; materials and cowponent development. including the use of ceramics; engine downsizing and packaging; hydro- gen containment and its effects on durability/ reliability; nnd lIIUltifuel capability. 11lE MOD I ENGINE The MOD I engine is the backbone o[ DOE's program. It is an engine which has been designed, built. and is now being tested within the DOE- funded progr81a. The DOE nov has four of these engines under testing. Two are at United Stirling of ~'eden (USAB) - one is used for com- ponent development and another for dllrability testing. A third engine has been installed in a test vehicle and is used for transient perform- ance and contlrol testing at Alierican Motors C~nera1. The fourth engine was built at Hechsnical Tedtnology. Inc. (Iff!) with _ny cOlllponents that were lMnufactured in the United States. MTI ts using this engine for compoh~nt. develo~.ent • To date. under DOE progr~ponsored testing, the total accUlllulated e.ngf.ne hot running time is over 1.300 hmu·s. Rased on the results of testing an car Her deutgn. tbf.!, P-40. the MOl> I engine is an b.'proved dl?sign vbich has resulted in increaSEd reliability. 1M jXl'dClt and efficiency _\~ured in the testing are vtary repeatable uid agree well \tith thle predictiol~.!! frO!!!! aMlytlc&l, cC'l<~ter 'I!IIOdels. All nnjor pl"~ram milestoucs including steady s~ste and transient .n31ne cbmracterlzatlon have been Det. em sdtedule. n.e trliPAsient test ina. \<'bicb inchlltl.eJIi the U.S. invi1'"OmllflJntal Protection Agency's (I1J'A's) ~s; _billions amd !\JIII1 ecOUi!,icted to be one-tenth the cost of the screeu. i'> '1111.8 it,em is a direct result of a gas turbine de'\Tl~lopill,ent. Coors developed 3 ceramic gas tlclrbine air preheater for Ii G~net'~"l Motors (GM) turbine vhich looks very pt'Ol'lIl.1iing for a Stirling air preheater. MTI is Jl>r~'::'3cing to rig test sar>!ple test secti«ls t;f tM.s technol,()ID". and if their rig tests are positive. MIl'I iJ;; planning for Coors to davel:>p Ct.1lT4II.!l1c ail' preltte. prog;t:'8Ill researchers have reduced HZ diffu- sioo through the heater head. tubes by a factor of 30. Sound progress has also been made in the area of pist,on ring developBlent. Friction and vear have been reduced by a factor of Z in rig tests and eo~ine tests are expected to confirm this. The third area concerning H2 containment, piston rod seal durability. has received a lot of attention. The current engines are using a pumplng-ring,~type sliding seal developed by USAB. lhis seal has shown goo~ results in steady state durability testing, but it.s durability has been somewhat erx'ious rule is, the higher the eogine effi- ciency. the smalller the mirror" Since the mirror syst~~--termed the para- bolic dislh--is s~~veral times lfI1i)re ex" pellsiv~ than the engine, thermal eHi,· cieney hllls at lev~~rage effect on over- all cost. ., . A IProgress Rep~fi' SOLAR DISH SYS'rms Presently, the point focu~ing sola\: dish systems utilize parabolic concentrators ranging from about 6 to 15 meters in diameter. The concentra- tor is mounted on a two-axis tracking mechanism that allows it to accurately follow the sun throughouc the day. Each dish furnishes concentrated solar energy to its ~ individual receiver and power conversion uni~ (PCU) , in contrast to central receiver systems which employ a field of reflectors (heliostats) to concentrate solar en- ergy into a single receiver located on top of a tower. The dish system is a modular or distributed system. Where- as for the central receiver system the entire field and tower must be complet- ed before generating power, the modular dish system has the potential to furn- ish pO\fer as soon as the first dish h. installed. For the near term applica- tions., the PCU will drive all induction gener&tor and the modules will supply electric power to a utility grid for oil and gas displacement and peak sb~ving. In the future. stand-alone applications viII be considered, such as for small villages. islands, indus- trial and military installations. Solar dish system efficiency. from solar input to, electrical power output. is the product of conCentr~tor effi- ciency, receh'cr efficiency, net feu efficiency (auldliades included). and generator efficiency. If the PCU is the Stirling engine. the resultant overall efficiency ranges from 26 to 28 percent. based on state-of-the-art technology. With improvements in re- ceiver, engine and generator designs. overall efficiency is expected to ex- ceed 30 percent in tbe near future. Additional benefits of the Stirl- ing engine in a Bolar disb power sys- tem include: '. thermal efficiency in- sensitive. to engine size and rated power. excellent part load perfor- mance: the hybrid option--the poten- tial to operate· under cloud cover and at night by mea.ns of foad 1 fuel com- bustion with a special receh'er: all components mass producab1e--a vital conside~ation for system cost reduc- tion. 1~R 4-95 SOLAR STIRLING El~GINE BACKGROUNDI - The solar Stirling engine has its roots in the United Stirling develcl1pment program going back to 1912 when tbe d1!Cision was Illade to concentrate on four cylinder double-·acting d,eeigns, rather than th .. classical displacer type. Double- acting engines have proven to be light- er, more compac:1I: and less cos;tly COll!.- pared to lllulti-'cylinder displacer en- gines. In 1975 81 new four cylinder doub1e- acting 40 kW el1lgine was designed and first tested hi 1976. Originally tet'1'/!- ~d the P40, it is now designated the 4-95, having a displacement of 95 eel cylinder. The design objective was to ~kchieve a relhlb1e expedm~ntal engine for the deve10lmlent of specific com- ponents. A cross sE!etlon of the 4-95 engine, equipped with i.ts external c(tmbustion system, is sectl in figure 1. . Twenty- fhe 4-95 engine~1 have been built f017 in-hcluse use, Ill'! Wt~ll as for testing by gov~~rllll!lent and PI' hate or- ganizations in this country, Bt'itain, I~r~mce, and We~lt Germany. An earlier version of the engine also played a key role as thE! baseline engine in the DO~:/NASA AS!:: pt:ogram. As of September. total test tilli.~! for all 4-95 cl\gines on d)'n@~oometerB lmel in demonstrntion plro- r.rmlls em:eeds ~~9, 500 hours. Th~ lO!.'1;gest time on Ori@ ent!~ine 111 11.500 hol.lu. The 4-95 bas been tested in such varied applications as ;'U gelu~1."vd of c:o~!lbuf2- tion 8yat~ cQ~~poneats, rath@r than developing new components. Figure 2 ohows 41 cross Ilcction of the eclaT Stirlilllg engin~t. As .can be SeeD in com- Blower drive gear Air plreheater Combustion chamber Fuel nozzl41t' Tw:bulato1: CORb\toUol/l blower: Ipitttt Fuel. puI1lp Ab: atomidna PtIDP Fuel/air coDt~ol. EDi8SioD controls Air,fuel.eXhau8t ducts Each of the above 12 it_ aure assemblies. ccmprlsed of lIlIat'ty perts. 10 addition. tbe solar engine driven access- odes include only a vatet'~. The efficiency of tbe solar eOfine: is btPIR than the fossa fueled eng De becauae of the sbsel!u::e of p8't8sU:ic lostll1!l:8 .8- sodated td.th the ccm1bustion air blower and variable speed drive gear. 'lbe con- bined advant.sges of fewer parts, higher efficiency and greater reliability in- CTeases the cost effectiveness of ~he solar Stirliag engl~. Specific modifications to the 4-9S engine for solar ~er bave included: 1) the design of a ··dry Sl8p" lubrica- tioo system suitable for inverted opera- tion. 2) integration of an im!uctioD generator with the engine. 3) a simpli- fied control system. and 4) the design of a "molar-only" receiver aDd eftgine heater (2018'[ absorbe1:) to match t:IJe BoJar flux patte~n f~om the COf~entra tor • Itef!~B 1 and 2 weTe done und4'!lt con- tract from JPL in late 1980. It~ 3 Wtclal 1 pha8e. 25 kV iMfJCtiOD actor of neeftt a.sip. Aft IDl1uctiOft IIIIDt:cn ope~ates 88 II generator without 887 l!iOdificatioDs. if CODMCted to • add. / / C!J.~~_ ......... _ ..... ....,,, .• FIG. 1 - CROSS SECTIO~ OF 4-95 STIRLING ENGINE FIG. 2 - SOLAlt STI.RLlNG ZNGIlQI: • I I I ! wilen its 8peed 8U&b~lJ exceeds 8Jll- cronous speed (1800 TpII) • The grid establisbes the voltage aDd frequency and aleo provide8 the excitatiOD. Peak effidency is about 93 pe1!cent. It b.,~, driven directly from the eosine tbro~g': a flexible coupling, and .a. iorear,atG4 with the engi~e crankcase by an alv-i- num intElTcasiog. The .. ine is 8Ce"fted froml tbe grid by the induction aacbiue. when the beater temperature reaches about 5000C. Power factor is coneetCid to about 0.95 by capacitors. Control system cbanges were mainly directed at siIlll,Ufying t..";~ automotive controls. Tbe principle of controlling engine torque byvaryios mean gas pres- sure vas again continued. Whereas io a combustion engi~e tbe beat input is controlled so as to follow the load changes, io a solar engine tbe bP.at input (insolation) canD~t be controlled. Th'erefore. engioe power must be adjU!ste.i to lfllatch tbe solar input at all til~B. This is done in two vays. First. engine speed of 1800 rpm is kept constant by the induction alternator when connected to a 60 Hz grid. and the alternator matcbes output current to engine torque from idle to full load. Second, the output from thermocouples ou the heater tubes. in conjunction witt, an electronic digital control unit. actuates solenoid gas valves t,o maintain cODstant: tEmpore., ture by increasiu8 or decreasing torque. If the beater temperature ~ac~s a Get point (about 720OC). A valve admits additional gas (hydrogen or bellu~ whicb increases torque (and hence po~er) to rcedl.lce the temperature. Conversely. ~ith a decrease in temperature. a second vlJIlve allo •• s gas to be pumped back to a storage bottle. Should the engine overspeed, due to a loss of grid for cl:-nt ovet'~:e8S I1\t Ul!\itoo Sti1:Ung Wf.~B not ~ell known, and the state of dewelo~~nt of slHll Br~l,ton &nd R.ankllne cycle tu'("- binet>\ was S(l'Mmu~t: o'l'ere~ltil!H.~te.d. 3lnd Stl- conrll. in l~mO. United St:idi~ ~~d'll! @l stv:ollg cQO!U.:m~nt to solSlt' ~iC SIS the p1.'ltrnPRO':IMA'J{l" 1 \'Ihlll()" H()t.'tiS l\,Of TOTAL HO?",1iSl SO\JRCE AIR CO""OllIO .... '1'''G. ""'l::ATI'-G A~O Rft AtGERA.ltQt\;, '-4(WS. JUl'¥ 1J '979 APRil" 19m J-A".\JARV I) 'M' rSSuES Fig. 2 Fig. 1 18 f1 ----- . different conce'pts with differing levels of risk and ultimate pe,rformance potential. Absorption heat pump tec!mology was viewed as being more "'''flll-cstablishe,d and, thus lowcr risk, because of similar cOmD~rcially available equipment (I.e •• absorpti.on chillers and gas air condi- tioners). HowE,ver, it offered only moderate fuel efficiency improvement. Heat-engine-driven technology, on the other hand, seemed to entail higher technics,l and business risk, but offered IIIOre dramatic performance gains. Table I com- pares the asses.sed risk and efficiency objectives for the concepts selccted for IIMljor prototype development efforts. REVIEW OF PRrrrOTYPE SYSTEM DEVELOPMENT PROJECTS - The absorp~ion he~t pump prototype dcvelopment projects are summarized in Table 2. One of these systems, developed by Allied Corpor- ation and Phillips Engilleering Company, uses an unconventional organic-fluid working pair: ETFE (ethyl-·tetrahydrofurfuryl ether) as the absorbent and R-133a as the refrigerant. The second absorp- tion project. a heating-only system developed by Arkla Industril!s, Inc., utilizes ammonia and ",'ater as working fluids and employs technology used by Arkla :In an existing line of residential gas-fired abs01cption air-conditioners. As indi- cated. both of these development projects have been carried out successfully through laboratory prototype tl~St:ing. Both projects yielded proto- type bardwalre wb1ch achieved the target heating COP of 1.25 io laboratory testing. In contrast, the two heat-engine-driven projects selected early for prototype heat pump system development, i.e •• the Stlrliog/Rankine and Brayton/Rankine projects, ~~ve experienced serious technical problems and have thus far failed to achieve their prototype performance targets. The two projects are SURRarized in table 3 The free-piston Stirling engine (FPSE) system deve!oped by General Electric Company (Advanced Energy Programs Department, Valley Forge, PA). ases an inertia compressor integrally coupled to the FPSE such that the engine/ compressor assembly acts as a single spring/mass resonating systea. As indicated, two iterations of prototype hardware faUed to meet performance targets and current efforts are more limited, concentrating on technology development aspects of engine/compressor coupling dynamics and engine performanc'} diagnostics. The second heat-engine projects, scaled for application. in cmmoercial buildings, is being developed by AiResearch Manufacturing Company of Table 1. Comparison of p~rformance potential and risks for lLJlHP concepts -.---_._--------- ---- Concept / Tee hno 10 i.)' Absorpt ion eye Ie (single stage) Gas- turb ine·-d r i yen (Brayton/Rankine) Ft'ee-pistoo·-St ir 1 ing engine driv'en (St trling/Rankine) Asses:o;ed Risks (technical and busines&) Moderate Moderate to High High 7arg<2"t COP..l for Protot~p.e Hardvare (:.e.t1ng/cool1ng) 1.25/0.50 1.31)/1.00 1. !oG/O. 85 ----._------_.- .J.Target fuel cor at rat lOb point of 8.3·C (47°F) il1»lftlt for heating and ))OC (9S0F) for cooling. where fuel COP Is ckfl-ed as the heating or cooling effect dividEd b)" the energy value of ~.t.H!' ~"'Jel us-€d. Yarget valu~s are steady-state~ excluding parasltics. Table 2. AbsOl"?t ion heat pump projet:ls Description e Organlc--':orking fluids (R-\ Hal ETl'E) Single--Sta.ge Cycle .. Res i dent ial • A::rub.7nia.-water Single-Sta~;", • Heat ing Ouly • R~sideQtial Developer Al \ ied COTpor..a i 01\ ~ (Phillip' Engitl<'e~ing ~,,'jor $ubcontractl)r) Arkla Industries • I...&b p-rototype cOlIIJd~te " 'Lh~eved 1.2, heat ing CO~ o Lah ~ .. (I:" .)type cOlI!Plete • ~"''''d 1.2~ heat ins ~"lli .. d ~'roje<:t CosIWRsvr<'arasit tcs) fell' prototype hardware .. 19 Table 3. Heat engine-driven .y.telllS heat PUlIIJ> pt'ototype project. Description Developer Status/AccOllpllshlDenta • Stirling/Rankine FPSE-driven spring/mass resonacing engine compressor) General Electrica 1'\/0 Prototype Iterations • Heat/Cool • Residential • Proto 1 syste1l tested at 1.2 COPH VB 1.6 g031 • Proto 2 engine 7 percentage points below "cycle goal of • Current UCC/ORNL project has technology focus 32X • Brayton/Rankine gas-turbine driven Garrett/AiResearchb • Brayton e3gine for proto heat pump 8 percentage points below qcycle goal of 27% (high speed rotating engine/ compressor assembly) (Dunham/Busch 6 Lennox Subcontractors) • Proto system. assembly for functional test • Heat/Cool • CO\1l!UerLial (rooftop) • GRI project near-term fo':us on engine Tl cyc Ie improvement aGE project cosponsored by the Gas Research Institute through 7/82. bGarrett/ AiResearch project cosponsored by DOE and GItI through 9/82 under a subcontract with UnLon Carbide CorporatLon through Oak Ridge National Laboratory (UCC/ORNL). California, a Division of Garrett Corporation. The system uses a gas turbine (Brayton cycle) engine driving a high-speed centd.fugal com- pressor through a magnetic coupling. Figure 4 shows both the compressor and the Brayton engine side of "hat rotating assembly. FIgure 5 shows a I1\('c.~up of the cvmplete engine assembly. in i"1..uding the combustor, recuperator, and sink heat exchanger. Protvtypes of this comb"s~or/engipe/ ~ompH'ssor assembly havt been fah:icated and shipped to Dullham-Ibsh ar.d ~c",nox for incvrpora- tion into heat pump system prutotypes. HO~lever, to date the prototype Brayton engipe assembly' .as only attained a cycle efficiency of 19% versus a 27% goal, despite extended testing and ~odifica tion efforts. Therefore, assembly and te3ting of the prototype, heat pump systems is being con- ducted lllOre for operational checkout and to confirm hardlo'are int.egration than for any Fig_ 4 meaningful system performance results. The UCC/0RN1 subcontract with AiResearch expired at ':he end of September 1982, but the project is being continued under the GRI contra~~. It is our understanding that GRI and AiResearch plan to defer the planned "Field Test" phase until another generation of prototype engine hardware is developed and tested at a cycle efficier.cy approximatply five (5) percentage points a~ove the current leve~ {Le., the prototype engi.~e ef:iciency targec revised to an approximate level of 24%). PRooF-OF-CONCEPT ENGINE/CUMPRESSOR PROJF.CTS In addi'ion, there are two heat-en&ine-driven projects aimed at laboratory proof-of-concept engine/compressor testing or so-called "bread- board" systems rather than prototype heat pump hardware. The concepts involved were considered to be in an earlier state of cevelcpment, without 0100. PHOTO 3759-80 0iIIfI. PHOTO 4Ol1-8Z ENGINE ASSeMBl.Y IIIOCKUP Fig. 5 sufficient "technology readiness" estllblished to warrant prototype dev'elopment. These projects are sUIlll!larized in Table 4. The breadboard engine/compressor develop,lllent by Consolidated NatUI'al Gas Research GotlIllany with Mechanical Technology Incorporated (CNG/tITI) together with the GE Stirling/Rankine project, wIll be covered in some detail in f0110,,11ng sections f this pape,r. The free-piston internal combustion engine/ compresso'c development by Honeywell, Inc. (Tech- nology Strategy Cente,r) with Tectonics Research. Inc,. uses a two-stroke, loop-scavenged, linear free-piston engine, dlesignated the Braun Linear Engine, direct-couplE!d to drive the refrigerant compressor piston. }'lgure 6 shows a sectioned Braun Linear Engine/d liuplex Stirling BAHP concept. The _jor advantal~e of such a _chine is that it can be hermetically sealed ill a single pressure enclosure and use~l a single cO!lllllOn vol"king fluid in both heat jlump and heat engine. A breadboard system t .... st of th~~ heat engine/heat pump assembly is scheduled for I:he near future. The other project involves the use of a kinematic Stirling engine to drive a conventional refrigerant C01ll- pressor. That prn. el\Si....-.!rivlog Int'~&lCal COIIiPressor) IlolNlywell (y""" ... ics ~1II. lI"jer SUbc<>ntrad'.<>d .. eo._ ... ~ d .. " .. l_t ""'I!>l .. ce/""""l ""at • 1.8" .,.~",Q ..,...t_: .. 1t()Of-oj~Ct>pt • Sti"U!l1:./SImli:in" Fl'S.!l-lnhea (Di • ..,,~-act .... te4. hydrauUc tr",,,,,,,.ud_ for COUl'ling to refda. COIIIC>'C"I.HI'n) ~It.:""""ch tl!I!I'X Itojar Su!)cwn~d • Cm1~ao~/U3M ... ,bd .... de~Q10f1iti"t """'Pl"'", • Fl'S1l """,U1eatloo • Lab ~- syst .... plaRM4 I l Fig. 6 Fig. 7 Fig. 8 confirBJed the early as&e8lB11e1lt of the tecboical risks associated with __ of the heat-ePS1ne- . driven concepts in coaparison to the absorptiou . cycle concepts. But: .ore blportantly. it has l11ustx'ated the ipitfalls associated with a "fast ~rack" product d,evelopaent approach when there are still aajor technical uncertainties. In retrospect. a lIIO're measured. sequential approach involvi.ng verifil~ation of prb:le .over performance and engine/comprlessor integration before starting any work on the Jpackaged heat pum:p system or attempting to aIlil1lyze consUiller acceptance seelllS to be a: more pru.dent and cost effective approach than the olle tak,en with the GE and AiResearch pro~ects. Of C0111rse, there was considerable pressure ill the late 1970's when those projects were started to ,lccelerate development and COti~ II.lercialization of energy efficient. potentially viable products 1)n the basis that the R&D invest- ment would be qutck1y returned to the nation in reduced energy c.)nsl.lfi11)tion. With that pressure reduced due to tille present administration's different philosophy. the other two heat engine projects hrllich 'olere in an early stage in 1981) were restt-Ictured to the present proof-of-concept engine/cofApresso:r developments. Decisions were also reached at that time ::0 initiate phasedown of the absorptiolCl projects and thle MResearch project. Theref,)re, the General Electric (GE) project is the Oldy one originally formulated and carried out under the previous "product develop- ment" philosophy that has been restructured to continue as a tedmology development activity. STIRLING ENGINE-J{)RIVEN HARP PROJECTS Attention will now be focused on the free- piston Stirling lengine technology area. The reasons f0r our interest in this particular heat engint? involve sleveral aspects. hesides its potential for hi:gh efficiency. whi.ch would make it particularly 'liell suited for HAll\, application. First. the Stirling offers very low noise chal'- acteristics cOllIp,ared to a conventional internal combustion (IC) lengine, since there are no periodic explCllS10na that blne to be ..tfled 8IId so valve so:1se>.s. Since it _ exteraal cOll1bua- tion and is tlius IIOre readily aUIICeptible to exhaust cleanup. it offers low eM1a8i~. The free-pistOft conUprat:loo also offers the apparent advauiltage of pure l.iIleur 1IIOtitUcn oil Stlrllll9llll.o) IWII .et>l~ /lUI In 1911 • I'tCIW II Prwr"", IlWIllv1!i! to;o I W1IU_ III IK'Orot'lll't ~e ~.llIffltw Proto I (<<""'let~<3 _Iv 19J"9) Wfj ~~" 2 IC(\'ilCh,""'" In 1S;'aU - uerfol~!t'ifflclmt" \1Mls IOI}t IIttIJl_ • TetIWIltl9Y l1trlltt IPm..-r III) I Fig- 9 Fig- 10 Fig. 11 -_ ..... . I~..., .... · 1diII,.... .... ........ --~ .. \r-G'III'C ...... obI\lff.IIfIllII*Id-lU~ ...... II1II* ..... ~ -ilIIII!IIIiIIIlN-'- .~4I!iIo~ ...... -- Fig. 12 hardware and Fig. 13 shows the fully-assembled prototype outdoor unit. Proto 1 test results are sUl!l'IlIarized in Wordslide 2. together with early results froiD the second prototvpE! (Proto 2) hardware. Because of thc Proto 2 engine/ compressor performance results and the develop- ment priority assigned to the perforrtmnce improve- 1l!ent efforts. Proto 2 system tests were never conducted. l..ad. of component testing capability for the engine lI,roved to be a disadvantage in diagnosing the p.erformance JlroblE~ms. Both the combustor and cC4llpressor were tested aa components prior to inte8r~lted testing. Rmlever, tbe engine perforlilance could only be deterndned from inte- 8l:'ated test res~llts. The Proto 2 integrated combustor/enginE,/compressor assembly in test is shown in Fig. 14. panent level performance data on the existing engine/compressor assembly. We still do not haW! sufficient data on band. for exaMple. t~ reach an informed decision on the overall viability of the GB englne/cOl~ressor configuration and partic- ularly its ~c sensitivity. ENGINE/COMPRESSOR DEVELOPMENT WITIl CNG/l1TI - A chronology of the develop~~nt project with Consolidated Natural Gas Research Co. and Mechan- i("u Technolc)gy. Inc. (CNG/KrI) is presented in Wordslide 4. The objective of the current progr8111 is the develop1lleDt of a diaphrag.a-coupled refrigerant c:ompressor for eventual application to an advanc,ed hermetic }O'PSE-driven HARP. The project scope specifically excludes engine dev~l opruent and r~uires verification te~ting of the Engineering Model (EN) FPSE performance as a cO?/iIPonent prior to c:rupling the engine and • • Wordslide 31 sumnarizes the final Proto 2 results and the conclusions reached subsequently regllrdi.ng furthE,r work on the GE configuration. The Phase III "Technology Development" subcon- tract with UCC/ORNL focused on obtaining COl'lJ- compressor. , the CNG(H71 engine/compressor configuration I PRCiTOTVPE 1 CONFIGURATION ----------- I i is illu£trated sch~tically in Fig. 15. which includes a S'lIlRmry of the principal character- Fig. ~3 I I I i ! I • IMJ_t 4I!d WUIIU of PrDt\I.l CIIIiIIlI!\1!lt "hlir""'" • Proto 1 CRiIIiIStmtelI Wd!!IIOOl fmS!SUIlI· at Mi1il'hIiII: aII§Ilrt$$Of IIIlW1' IfllllII'IItotllDl. .... feU $111ft fir. "'6lt- _tGrf!llH - SVSUlJl 1JeOt!ll9 CD\> If"'" DmiIIte t.n ,- 1.2 ft 1.& _ - SVSte0 CliQloo alP elS"C -It.!I·ft O~fIS I11III - £n!Jlne _ IlUtWt 2.1 "" ft , Uf _ - El'fJIM ewel. efflclentY _ Y& _ 900t, • IUSIIln IIOOlflootl_ In Prow 2 to ~ ~ II!IIiIIGtIIlll ~, IIIiII I'fl9!vCe losses vlelcr.o diSIlEOollltlll!, Dll'fCMWlllte results - 25l! ""I~ _Int efflc~ lit 2.r.> Hi 8UIIlUt _ Vi lIrOUIZ goo! 01 mot J::It - ~ 0Ir. uwlro GbsIrI!II!IJ ___ 01 _Ilfi IIIIIM. raklftG ~_ C!!IIIWRd to_ Words1ide 2 Fig. 14 6£ Pi1OTOrm: 1l(:IU~l ((OI'ltll'>.ll!<2) ~t I/I~lfl{!d FI'Sl! Ylel~ hl1JlUll' eftLc!4ll\ty (17-2l!ll lool~~<:ol). oot ':llN!lltl 19: 1931 1::oD~tOfhDlltllU C~f1IS${If ~b "'~lv. r#J; WSWlI Iflel tefiUI til Cl!r00 __ -..... --... .--~ -.. .... --..- . ...---"'-~ .. ~ ·,.,,_ll __ Fig. 15 istics and design features. FFSE operation is similar to that described for the GE engine, although there are certain design features c,)nsidElt'ed propl'ietary by NT!. The COl.ilpressor and coupling C(l'IICept. however, is cOillpletely different. In this concept. power is transferred frol~, the engine through a flexible metal dia- phtagm and bydx-aulic transmission and deli"ered to the refrigerllnt cOllipressor (thr:ough the volul:M:!tric displace~nt of the diaphraglll. and co-rresponding displac_nt of th.~ oil itl hydnu.Llic transmission, t\J> the cOlilpressQT piston). The hyJraulic tranS11ctssion is cOllsidl!red as one sub- assemhly. cons-is,tins; of the engine povelt die.- phra~ID. gas splti,ng diapb"cag1l\l (x-es\;ot'ing; foree fuuction), trcms;"erse vibratiot\ halancer (countel'- ~ishts). and t~~ bydr.aulic oil. The c~~ssor s\~bl!sseebly includes the cylinder heads. valves, pistons. lmd thu refrigerant gas. The three subass;mblies - .engine, tr&ol>lllss1on. and 27 l~Olll'Pressor - f01:10 a coupled resonant system. One of the potential advantages of this configuration OVf.!l(' the GE configuratIon is' reduced dynamic complexity. The use of the power-transfer diaphragm has eliminated one degree of freedom in tit<: r'esonant system, -.mtch should i2l!plrove its operat tng st,ability and control. Of course, lifetillite of the diaphrlAgill. whic,h lIIUst undergo so~ 109 stress reversal per year. bcco~s a cl'-..u:ial question: pyesent evidence, itlchlding operc&tins. el'perience in England with diaphrap- seald Stiding enj&:iIHls. strooal.y indicates that di~phr.~g~ material and designs can be selected to give infinite fatigue life. Figures 16. arul 17 are photogl"lilpM of the EK engine bard'b!i!txe which show that there are also SOOIe differerw:es froa the: GE 1Il&chi,ne in FPSE desip features, notably the 8Onollt~~c heater bead conflluration. :':udsllde S SUIIlIIliari:aes the current status of thft CNG!Mtl project. The next year is critical Fig. 16 Fig. 17 FP<;;( -0!I"1~ C()H9llUSOfI lI£'Ifl()l'llElil 'ClI'oIIIT! SUIliCOfltnX! J C ~IC(/Q'I'I.. $<""" _un ClItY'~Tl S!lt~lfl~, _ of l!'l u"'l~ (ok>~ O'«llll;P.f~ In<) tllt . Ii ~II ctcsl'VI "'-"'~ ~ <>!t¢ll1Q _1~.1!1\ c ___ • ~I.C InlIlliPl!SSloo. (!1>1 ~le~ JIm! I~ IIfl\1 cll c~~t\t ~fe Ot~ • ~euw t_: taUI\llIltll'lIf~ S¥u. TfJStlllG W>IlMIt! Cl!IBlt'ated to life requirements and cost must be a continuing concern in the develop- ment process because of their critical importance in the eventual applicatlon in "AUP's. T,lblc 5. Current appraisal of key issues FPSE/compressor technology Perforll'.anc'!\ Efl'iclency (l> '-PSI: efficiency (SO..\ and potcntial 'dth mature techuology) e En&ine/co~~ressor integrated perfQrmanc,~ dyuaRlf.c sensitives~gn life vs heat pump requireillent.s e Service calls!_intenance requirel!leDts ------~-- Fig. 18 STI RLlIiG/RANl(l~ TEChltOUlGY ~EW DEVELOP~~7 ACTiViTIES ORl'll IntlOUse - Frs!: IKlnl>l4'Ore 000 Analytical Tools AssesSI.lIeI'It II Survey/evoill!Jte dliflOll'lIC ()l'l(j thenwl CIldes e Document (NollotJle FPSE ~rtmentol results. MSIi-LefU; Interagency Agn,51lCflt e Experlwentol tests to Drovlje dOta fOf' ~l volldUtlon (FPSElcQil'.t'/OOt'ilt ~rfortl'!!Ji'ICe) e Emlurance testing Ar\lOOIle NiJtlnool loo - Cos,OOl'lSOrel1lL1ith OOEI£CU'i Prrxln:flll fI O~clllotlng flQl>l tests to provide ht.'01t transfer. ~ droo correletlons for anQlrtlcol ~ls MGrdsHde 6 --- .;--.-_._-. _.-.-.... Tbis papel~ represents an attempt to describe we have been. what we have learned. and we are ,,,lug in development of technology a,'p~:lCII~lLOll in future heat-activated beat ~pru!Sl,S has been plbced on Stirling B,lI:ioe··dl:h,en IIAHP technology, with its many ~GA~~I~J'Ua developaent problema, because it vas ifitHi as having high potential for this c~pp.LL(:at.Lg'n ami that positive assessment {of its potential and other needed continues. Based on the review .i';rll'csented in the preceding sections, we offer the following SUllI!!lIIry observations and conclusion. III In retrospect, the previous "Product Develop- ment" efforts on engine-driven HARP's were premature;i i.e •• they vere undertaken before the technology vas sufficiently advanced to warrant sllch an approach. Cit lne techn:Lcal problelils are now better under- stood and can therefore be broken down into . morc n\anaJ~eable technology development tasks or projec1ts. • It is still not clear how best to accuate a heat pump cycle with a free-piston Stirling eqiDe. Until this load-eng1ne coupling aDd CODtro.l iS8ue is better understood and preferred engine/transaission/coapressor c:onfiglllTatioos identified, it will be dif- ficUlt to U1Idertake or properly focus R&D em such critical issues as durability, relia- bility, or cost. • To the extent feasible. v~ plan to use available engine technology rather than to develop it ourselves, so that this program can concentrate its resources on the issues related to epplication in BARP's. • The free-pie ton Stirling engine-driven HARP is still an attractive and interesting equipment option for the future. but it continues to involve high risks (technical and business), even after several years of development work. We view this conference as an excellent forum in which to present this information, so that we might obtain constructive feedback from you. Therefoze. having presented our aasesament and current views on the issues and our planned development approach, we ask for your guidance and input. QUEST ION AlID ANSWER PERIOD Q: IdMt ~re your cost goals Clr1ginally when yoo S'itt out on this product de\1elo~/jt trrork? A: OUr cost ~Ioal t.'illS eft five-yea\" ~back as opposed to the ooarest·equivalent product. 6E did ex1;eflshe lI'.arket e\9,~luations thr1lUghollt the course of that de ... elop"~,:mt work. so 1:hat value floated S~. and as a matter of fact. the neares't eqUivalent product cha~~d ft'illil a trlgh efficiency fm"I'lG1Ce/lJdr conditioner cmltbin&tioll in the beginning to an advanced electric heat pump 31 at the end. But ilS I said. the cost prerailllR was geared to a fivt>-year PflYbaclt. and so it depended on the area of the country as to what you couid afford to sell this for versus the competition. The northern states look better for illut type of heat ii'Ct!Jated beat PtMP because the primary benefit is in the heati ng operati on. So yoo aN! looking for II location that has a high heatif~ load as compared to cooling lo.v.d. In general. tMt probably translated into something like a 2S-3Ot cost premiWlt if I ~r correctly. .- ·'i , . . , I :P~ .• W/lfr'r J __ ~~ffl ~ ~~ ~otential applic8tion~ for Stirling engines in the power range from 0.5 to 5000 hp. App1ications are grouped into a snaIl numher of classes (10). with the applications in each class having a high degree of cOll!mOnality in perforamnce and cost requir~ments. A review of conventional engines was then undertakel. to determine the nature of the competition faced by a new engine systew. In each applicatiQn class the Stirling engine was cOfApared to conventional engine syste_. assUIl1ing that objectivea of ongoing Sth'ling engine development programs are met. This ranking process indicated that Stirling eng.lues showed potential for use in all application classes except very light duty applicatiocs (lawn (!lOwers. E,tC.). How-ever. this potential is contingent on demonstrat·n~ much greater operating life and reliability than has i>4!cn demonstrated to date by i developmental Stirling engine systems. ; .---J STIRLING ENGINES have been under develo~ mel'lt for OV~H' 40 years by organizations in Sweden, The Nether.lands, and the United Stl!ttiS. Ho\rever. the interest level in the StlrHng ennine as a clean, efficient potu!r COllV· .. :ter hus increased drlUl18.ticall.y in the last 8-10 ye~rs as a result (.f r.ising WQrk oU prices and concern for the enviroHment. StirI1l1,§ engines have a Iltwber of poten- tial adVallt@3Cs which have provided th~! incentive h,r these pt'ogra!)!s" including: !tl!ll.!.-:.!~el C-!'.R!'.bHity. ... hlch &lleus op~r8tion wJ,th a wide r81l&e of fosdl fu.els. as well as nOl'l-<:ollventional heat inpt!t:s. ID1Ch as solar en~,rgy. biO'Oilll\ss. o\.\cle-1l1', tAnd thc':-;Ytlil.l storallie • R~..!!~~);...!!.!!.£!.~ lID!ch resulu fX! _re 6conOOlllc operation in thoae appllcatiol!1Z vbere fuel (:051:8 are ill!pOlCt&nt. ~ EWltJsion Le'VIllls in fuel fired appU- c.ti~a re&;ft of t.liIing external CQ'El- .. --~--.-.. . "'~i"""''''''''lf . ":"'i;:: ".J Stirling Engine Applications Study w. PIMW Terapn 8'Id David R. ~ ArIIlur O. I.itde. Inc. bustion jmgines. This advantage is particu- larly il!lportant in vehicular and closed environmlmt applications (_ines. etc.). LOlJ Noise and Vibration resulting frOtlll the uS;-of --mechanically balanced mechanilllllS. the lack of valves. and relatively low operat- ing speecllJ. !!'&!!.l'~..!!..l!ens!!y' Potential when operat- ing with hi,Sh pressure gases. This advantase is often important in vehicular applications. !!!.llh Re~.li~nd~~ng Life resulting frOlYl outwardly simple IIh:cha.nical config- urations and relatively fev moving parts (no vdlvea. etc.). . Good Part Load and Variable Speed cbalac- teristicli which are illlpOrtant for vehicular and s~ generator applications. Many of the above advantages have been deNonstrl!lted in operating hardware. For eXld are 1W1i. titl.el\ C:OiIIbiufl4 vith _ller Carl,h pl'ovidlnl1$ ~roved m11eqe and _1s.iOll. charactQ,dstics. TIle.. c .... r.ct.riotlca an , acbieved with enaines having a cost ($25-30/kW)vbich probably c:annot be achieved 1ri.th a Stirl1na engine - ev.m in _ss produc- tion qwm.ttties. The projected perfonllllnce cbaracterlsU"· pf2)*advanc1ed autOll\Otive St,irling enSinee(' indicate. however. that SUrlina el1\gines l18y bave efficiency. fuel flexibility. and _i88ion advantages over conventional I.C. engines. These advantages could becO'llIe increasingly i,aportant in the future depending on cost and availability of clean automotive fuels. As a practical matte~. conventional I.C. engines can address many of the applications considered for Stirling engines. I.C. engines have the be'nefit of over 50 years of extensive development and a firaly established sales/maintenance infrastructures throughout the world. As such. Stirling engines vilJ require sq;nificant advantages over conven- tional engine options in order to result in a significe.nt market penetration. Current technology Stirling engines still have not deoonstrated the lHe and reliability required to address the applications for tmich they are being considered. It is not certain that the t,~chnical reasons for the lack of demonstrated reliability can be successfully addressed for the mass market applications. while still maintaining the other required attributes (for example. high efficiency implies hi.:gh operating temperatures which complicates; the task of achieving reliability and cost g~~ls). Many 'engine systems indirectly utilize the production economies of the automotive and truck IIl8.rkets to maintain relatively low engine COS Its in a wide variety of applica- tions. Ex!ll(l}lles of this include engin(! driven pumps. inb')lud marine engines. and standby engine/8eUe~1rators. which often use autoX'llotive or tl-uck engine blocks as the bas1.c bl.'.i,lding COlll!}Oncllt. St1.rling engine technology vill be at a disadvantage in such applications if the autoll1Otive St1.rling en8ine program is not pursu",d. Appli(:ationa requiring unconventional heat inputl; such as solar energy. can often be addressed by other exterllal heat input en- gines. FOlr eX8.l!lple. several studies indicate that Stirling engines C~l'1lbined with hish concentrat:lon ratio parabolic dish concentrators lire an attractive solar power option. RDt>lCVer. there at'e several options being acthely pursued for solar po~;ar includ- iU$ pl\ot:ol1"lt~ics. solar driven RZlintdne engines. and solar driven Brayton C1\3ir,es. The cl'l1l(ly '~t~ge of dtlVelopment of these solar pOllet' technologies cOfI\Plic.lItes the task of selectin& Ithe system vith t,he best CQI't!~'Cciove factors llrust: be addres!led ",hen coilldderiftll the prospects for Stirling ensiue ~e;.:s-r;;parelltheselll designate refenmces at end of paller. commercialization efforts. In particular. tbe issues are: Fox' ubat combination of applications do Stirlin(j: _sines show significant advantages over probable cO\IIpetitive sySUII!B? What operating charact~riatics and cost goals BmSt be achieved for Stirling engines to result in large penetrations into such mar- kets? Wluilt is the estilllated size of potential markets for Stirling engines. Whalt a.re the operational cha:-acteristics tbat Stirling engines would need to have to penetrate these markets? TId,s paper sUW/JIIarizes the results of a program sponsored by the Department of Energy and NASll Levis Research Center to address the above is_s in order to detcnrlne which Stirling engine applications are most likely to be successful and what emphasis new R&D initiatllves should have to accelerate the introdu4:ticn of Stirling engines in attractive applical:ioo areas. CLASSIFICATION OF APPLICATIONS A revi~¥ of the literature supplemented with conversati?n5 vith industry participants identif:led over 100 applications for engines. Kost (at least 90%) of these applications are nOtlrpt'lized into ten categories having c<~n IeQuireIDeuts. Information provided for eacb «:lU$ of applications inclooes the f 0 llowi.ua: - T~ ~r requirements of engines ComBon- 1)/ utilillg Fans Poetablll Refrigeration MObile Refri~ration Gas Gather i ng Third World or Remote Power Generatio1l Oil Pumping E. Low Usage Equipment E.l. Low Power Comp'''!OWfS (Consumer) (Gas) Ge"""ators (Portablel (Gas) Gflntn) Pumps (General Purposel Log Splitters Chain Saws Sno",'flwbjles E.2. HilIh Pow/N' Weldl>fS Pumps-(»ntrncto: ~~ors (Ernei'\jeftCV) E.3- BacI<. Pa,c'", Power SOIpplv 2·10kW 3().6OkW 100-200 kW 15-175 kW 5-!525kW 20-500 kW 6-475 kW 1·560 kW 3-300 kW 60·450 kW 8-50kW 25-450 kW B·I50kW 8-200 kW 3-12 kW 1·10kW 1·10kW 2·2OkW 1·12k\\! 2·8kW 8-175kW 12-425 kW 11·500 kW 1-4 kIN } - Lim nom practic:e to dat1l - Large potential if technical and CO$t goal~ achieved 55,600 61,400 26,100 331,600 27,900 7,400 - NCP" - Significant potential for space applications as spal! pow .. , neOOs increa9!J 21,500 Small Large- i)Otenti .. 5I for bionl ... "''' fired systems 3S Small 10.3O{i 2fY.i.200 9.92'6.000 11.400 144,600 2,473,600 101.500 9$.000 3l.SOO 169,700 Qualitative Raquirumtlllts Long life High efficiency low noise & vibration - Low emission; - Heat recovery - Very high reliability - Low maintenance High efficiency Long life Low emissions - Average cost Good load fol!owi "9 - High reliability - Very high reliability - LoO!llife - High effIciency - Low weight (space applications) Low noiw and vibrntion - Good loaJ following "Low majnteoaflC."! - LO:1g life High efficiency - Multi·fuel use - Simple construction 8t maintenance - High reliability - Lowco.t - CompitCt .- Simpre operation .• Lightweight. - High reliability Table 1 (Cootimtecl) G. Mobile Light Duty Passeng.er Car ArFicultural Eq. SIlIt-Po_ed H. Mobile Heavy Duty H.t. Small (t·110) AGricultural Trat:tors Trud<.s Construoction EquiPl'l'lel\t Marine: PiellSillfe & ILiftit Commerci~ Mining: Surhlce Mining: Underground ForestYy Equip. Railroad tJluintenanQII rtf.2. Wig~ Povllli Applications 1.1. Solar i'o\~ Pumps SQI& Powll'fed Pumps t SoIll'T Po\l\>l'rca OoJl'(}reSSOl t Sn~ Po1m:red Altem!ItQrs Di;;b Mountlld ~N"iitOfS 1.2. The",..,al Storil9! ApplicwC>M (Unduwater) <:t5kW >15kW 2lHl0kVl 9-4251(\1'1 16-110kW 6O-110kW l-1tCll;lN 2-110 It \II 20-110 kW 22·110 k\'lf 22·110kW l10.350kW H(}400kW 11().5SI)kW l10-300kW 15-2rtlOkW 6O-3IlO kW 1,120kW -l().l00kW -1()'50kW "'lininG Sul'Jll'&MilWl - 1()'200 kW Miliwy Sub'IBMkw 1'IeC!$'Jre Soot Total EM'fID' SIrs.. Gl!m.iOlIl'w~ Sl~irul "-$WI Sl.!bmUlif~ Off SMre Ex!lfo,rIl'lolV ~"riM UfHnanmd S\J.flMlill~ SI.!~i"" Short T_ ~mll!r ~1t 1.3. llt~rlm& StC>f - t.!j,U 11.\'-./ RI<~lW!fati'W G;·1lk.i~ ~J'l fmHO\II,~s HvbIId Vooidt Wh«'I;:tuIr ,-..... fAmtuIJI) 6.527,800 36.600 144,100 1,145,900 213.400 1,500 400 300· 43,300 1,151.100 41,100 58,3()O Small 8,100 120 - Swlm!S OOml dl and vibr.ltion Table 1 (Cootiaued) L lArge Multlfuel Munlcipsl Power G_tion Industrial CogImat'ation Gas Pipeline °Estimates. '''Nep - No COf'runm;ial Praclice. BF.AT PUMP AND TOTAL ENEllC'i' - In & heat pump/total energy application. an ens1~e would need low emissions. II,GOd fuel efficieJllcy. very low noise and vihraction. heat recovery. infrequent lUmtenanc:tE. MULTI-RIEL A.l>PI.IC~TIONS - In a rural po!ier system, fuel switching. fuel efficiency. 10'1 maintenance. long life dud startability ar.~ important chan~cter1.8- tics. Low e~issions. lo~ nois~ and vibration. heat recovery and engine size ar,d ,;eight: are not critkall. I.OW USAGE EQUIPl'lIiJlY - In low uMse equip>ll'l:nt the IS;:!iIin factor for success; are very lOt1 cost. Btartab:U:lJtJ. l PDNIDWiC1t C'!W!ACTEltlS'rICS H(lSt, 81W1ic:&tiOllS heiag c4mld.ftred for Stld~ ~ine8 are prenatly l1.flIhl8I &ervN or coul.d be S!Ill'VM by OIlEt or VIOre eOtllV'CIlIlltlMl&l engi~ fIJ&t • .-. 113 & prllcti.eal _retet". SUd:bl/lt enatM8 ",111 Itim;ve to sbov 80ft cOll1b1fJ4ttotil of teclmlctal a.d ~te ~ t&~.8 to displace the ~~¢fttlonal ~~ ~ utUtad. It t.o. ~t:GfO". 1IoJKp"t:taat to ~ I!150 >2460 293.672 ll,565.662 367,622 227,543 <1500 est:. 'i'"iSUIMlt &»:4 1$0 lap for vilhlcular e~~HC&t~.on\!l. ~2~ of t~~$~ er,e for &~t~¥l~lw~ u~e. !~ elVer. III lIIi,I£lfA:U1C".4W.t Q~lt 81':'& all«O l!eM 1" 001::1'11 fti"&l'lllc.lIi't!'~!:.1iI 2$ Usht. tll'UlltG& end ~r~e tora. 0'Il0~" dO£erl Wl1M!lUflilcturu6 (pg-h;ad,ly 8li!l:(I!Jl@tive C.Gl'!It~) pll\t'tioC~a.efll in tM,~ aaxM& alNltl. The sales distribution of D!~6el eusines is 'IIIOre e11oo1, distl"ibuted than for spark ignition latl,lirul!s. Vi.despread applications for Diesels mel_e C~1te8SOr drives. far. equtprJ!.P.Ut. and &aerator seta. lIcteever. approxiutely 60% of Dleatel sales are fot' autO!Mltive and trw::1t propulsion applications. 'll'ithtn the ~r ranae considered the reCipl'OC4ting inteT~ eO~U81:ion eoslnes are shllilar in d!!isiall and COIlCt $2S-40/k/V. Nou··a\ltOMtive agiufm lmve e o!E~rdUctW.tly hislwlr cost ($1SCI-lOO/kll) than thdr tiut;mo~ tive O~ s~li"k tmnl.ticm COOl!ltlUl)J1lrts. kneUts d®dv~ f~@ thh s!pUlcwtly hl~r CO'&t Ind~ td.f~'lIr .iUd-fIlley. 1ft tiM.! 30-151 raJ:lli1e~ !mill 10~lt lUe (up to ro~OOO-30.000 h1Yl.l.!i':s). 1'00 b!{i~ C{it1;. of the~'l\\ ~.1nliUl) f&elUt.1i:.@ tl~3t ti'1.@ effiei<'SllS;;Y of 8 \l!all~lTI'rel@~ SUd!1tl$ ell:Sl~ MJ " Nli:tli:11: tb-sn Dl~lll~b h\j t:M h~ &,~ rlm-i~. Giffilul'tn AWl t.O\f Sl"~ DlanS - 't1;$$@ emZt~1~~wUc8tl~$ ~rflt lQll~ IttQ &\00 hQ;h "~Uity 16 ~' .... MIUltaC ~ CiOM~ ... ~."~. .&.," .... lttn ..... _ eq1uU' tit.!· ,'.,.. C08tft ia th'I $200-_JW~ ... fte; f~,efftd.., .. of thaM ......... 1$ paerally,1I'$0 1It.,,(l,....,., and. 1a III6ltthle., 80IMI ~ ••. m dah eta .. · MY. a 1t1dt_ aultl-ful' ~~'. ~l. are fttI'l em: anytM.q h_ flo. I DlueJ: c10wn to t~,""· cliatUa.t... deb: _ ~; "G". !he' IIIONt COHiOllo IU$Otil8 1I~1 is'DabRal au. alt~ all "xu. of othr c~tAl .... eova fWtla such .. ~ ~. _ft Mea ueed. Theae .~ aN uoally re1ati"fll! heavy aM IraD:.y .s ~n4 to the ~ spMd" 1BI8- ~... For eJI.'Aiil'iPle. thair 8p1!1df1c:: 1iII0iah.f: 1.8; tnleaUy io the 10-30 qIW ~ .. ~re4 " 8Pftlt 1pitioll. aut0lll01:1ve type ~d with specific ~t8 of 2-4 1lI1W. C'oIiJ.oe..quutly. there nIl he COfl8UeltillW.. ileld.Mltty 1. the phy1ltiClil dnip of Stb:l1q ~ (",be. we1aht. layout) __ wle4 ill IIlWu'caUou now sened by 1 .. speed interul ~t1on C!!Il81naa. A ~ery 1tI!\IO:rtaftt. feature of enalnea in this cl8$s 1a the1r hi&b rel1abiUty as meawre4 by _btt~ utervala and useful life. tf.!my ~ 10 tid. c:l~U!1S bav& li'ge.· in ftCeB$ of 20 .. 000 "0 (t1_ to _jOlt overMu1) and vUl oJl!lll'ate ntb Qllntell8ll.CQ iutenals of 1.000--2.000 bourfl. The excep- tional reUabi.1ity is in a totally different class thlm tlMlt: acld.eved or: need" by 8.Ut_ tive e:naiaes aM coWd be one of the lIOn diffimt a,oala t;Q be .. t by III IMV uaillO devel~t. 1l P!'4kcti. to date ,~ Jr~ltM 1m e<1l6ta Ia ti',<:t $1.ooa-3 .. 00G Jl'lkl" W 1t~. 'l'oj:aetl008 for lllU\'~r ,1~U. ,~iU..Jl) at:t u "he $!iOO··l~ 1'." •• , «hJlGlllCltrta CI'Q C<:lmcit'l 1&t14. opelmtUs t_$'1.' Cboracterlnica Of ",Ee8eIltatJ.ve eon".t1oul IIqfJIIes ~""""" ~ ...... - """ ~~ Olt'1 ~- ...... _ ...... - "".IIN GuooIfit U(l3IlOO -....,;-~~ --""""', f=-,,-_to - U(l1Il!lO U"A) - _. U!\IIt DutIl I aM G&I;aIiM 82$4Il00 -lIoIIilt_o.tlII 173C1O -_....,ioI~ - H""I'urllplH_£nfilIv CATERftLLAft o;.m 1OClIiOO - Hililal\f l!l1l( - CIoI .. F_. Diaml Gal. _«>000 -.. ",_Di1;tiIb ... 311 TO ""- ... """""" - l_sa-. .. ,.V_ "",..,;0 nw...I Alliron K ... CSIiiI"i'R.J.twwa 3120. _olGM SOtMl -!';:- "","..., E ..... onJI'o .... _'utI t_.ft.GOO .- ~OO.G.. -Sl>!r .• n..._ -- SIloC'- blforutioft is I,resented for each representa- tive engine to I'1!'Ovide a bencbl'llalrk by ¥bieb to judse Stirling tmginl!s in those appl1caticms. Also noted is tbe production volume of the represl!:utatlve E~uiille. there Is UII) single set: of technical or cost gools uhicbmust be achieved by Stir1in~ engine systeos. For e~le. automotive applic~ticlns selt particularly stringent cost ri[,quir~nts OIl the Stirling engine (about $25/kW) but onl], requil1'qzs 2,000-3.000 hours of operation life" which allO'WS additionlll fIev.bUtty in tbe choice of bot section _ter1~ls aOO sjfsttil'!ll design. Itl contrast. ~ h~at p_p applit:ation Right allou costs 4 to 5 tlw~s those of ,an aut~blle engine but would u'1IUb:e II useful life of over 20.000 hours. As noted on Table 3. thcn~ are senne applic:&tions ubare tiWtre is no present COll!llllelC- ctal practice. vith conventional engines. Thellio applicatil~lls include nuclear/space pover .t.ld lII·nl8r PCMl'lt. Fml' these ~pplic:ation clI'lGIUl?B tM pOli:slble C~I:1tiV4~ engines are tl'i~~1ec:tdC:8. Br&lyton cycle. end Jtank1t\e cycle e.'3$1nelil. E\_ th~:!~ Sfl:b:l1n~ Im&i~~s have be0n Ulli! <200 and eost characteristics. A b~ief overview of the devel~t ~tatu. is p~ov1ded below. lUNlHATlC DGINES - The aoat extensive recent experi_ tbat is well-docuaented with kinematic Sti~lb\g engiaes bas been achieved with those base4 on tbli! 4-95 (1'-40) engine designed by Uaited Stirling of Sweden. Various \1I.o~U.fic.atlOl1lS of this engine have evolv·ed ovey· 8 J'tCr:lod of seven years aud it is the- basis of tbe troD--I ~lne. being developed as part of th~ DOR/NASA Advanced Aut~tive Stirling Elll~ilw! (ASE) Progr_. and a solar opelfated ell,line. whicb recently initiated testing as ~'tlo')the JrL solar the~l/parabolic dish progr~.· Yhi$ engine is a four-cylind~!r. doubl~mctiua configuration wieb can plrodaee 40 W (55 hp) unde~ tkIs!gn condiUons. A5 of Jiil.IN&ry 1981. 21 enalnes of this baaie desip twl heen built and O"~ 13.0~) hoo:r~& of GpeUUOOI had *8 accuaul_ ted. H~r. too ac.cwrulmted hours of o~nl)u.cm 1IIlI ... e u,'&I.KIUy ent.t\Ued mI1Hl'WS unplanned .1tII!~ aQlll the rdiability of critical &.'Uhsjst;4M1l& (pr~~nJ sellls and he~ter ~&A~ &~ still In qu~stiOft. Host ell the foUow:bIC cOI!!IIWmtuy on the p,z:do'(_~ . ~actfllrl8t1c8 of kil'Mlm!ltic Stlrlhls ~ b b.lt1ltGd on the 4-95 enatM eM itfJ UI11' ~t d-advaUvea. IIWICIUKi - Stidllrlia as1ne eff1dencies of ~·~ra c4Il'ftldat_tly d_stuted Oft tut ~ .,~utiO& ~a for over 15 J'0>&'l's. e I1DH receat t.estu with the tIOU-l fmi!l!l\e aM sola- ventca of tMI 4-9S haft ~t~&ted .fflci~ levels in exc:eaa of .\ ~i ,,;, 35% (iIKff:':r~J 1mnIer aud parasItic power 10 ... ) ° 01lllC! projeetioDs ~ IIASA 1ncIIcate poUtllUal for alltOlllOtlve -aiDe effic:1eac:lea in the lou 40% aDll iD the hip 40% for cerhin statloDary: applicatiolls of aut:GIIOtbe, clerlved eastne appUcllltlons that do not uae a c~tor. 1.,e.. solar. The e'::fieiency capabilities a,f Stir1:tos engines ar",. there- fore. wll-dUliOnstrated. and fm-ther impzove- _te Idgbl: be expected. as hfa;ber taperature heater head aaterials are developed. NULt'I~~ CAPABILITY - Tile HOD-I engine has been opertilted Oft II!Ost liquid fuels (gas- oUOEl. Diesel"t}tc.) of near-tem interest 88 a ROtor fuel.' Philips operated a bl~ss fireiilat .re,:,i.:.,,:.(. eufffc:1at for aU' .11CA11~' of ~... '~)l:l~, PMT LOAD OPIIA'l'lOR! - ladle' SdrHat7 .. /!,;.,:. eaa1D~ outpat ii'" ~:hIul; to, th; ,;:, worUns pe pressure ara4 tlae ~ "o~ .. ~ therefore. there are two: ~ _thoIIe of cwtrollhg the poRt'; out""... oa. la· to<: adjUSC the vol_ that 18·...,t ad the other is to adjut the Mall pre8llmft of the. eqtueo wnsally iUi c:onjunc:tf.cm with a c:btBDge in the, .. rpta. Host Stiding engtnu· to' elate. mel_baS the HilD-I aye colltrolled by ecIjUBt:iq the' ¥orkin&: SillS pressure 04" rpa of the enatae. bper:lence on the ~·l eogines akIw excellent part: load operating characteriati~l~ch is critical in vehicular appl1catlor':9. ~...lliB AND ~lGBr - SUd.ina waines developed to date have _11)" been ~t heavier an.d laraer than comrentlC11&l1&l el1$:lDes. ptlrtiwlady in appUcations ut1l.Uiq li&ht duty Internal COIIbustion enatnes. The priDary reasOYl fOl~ this is dwt SUrUns eD3itle8 require a relatively large and c:oaplex ex- ternal ccnabustlon system. Dds cOlllbuatlcm systellll mcl'lDllles the blcmer. heater head heat eltcJumaer. air preheater syst_. lmlulatiOft and associated cOlltro13. In a~!dition. allllost all the waste heat (85%) in n Stirling engine IlUSt be rejected through a radiator Un air cooled aysteas) as COlllp8{toi 1:0 only about: 60% m au I.C. en- &lue. I Ooe o~ the _jor focusses of the autOlllO- tive PZ03:ralil MS been to adapt the 4-95 desislls to result m engin_ of acceptable aize and ¥eight for automotive applications. This pJrogr_ has been successful m that the KOD-l atyle engine h&s been installed in the engine cOlSIpSrtment of an Al&eric:an Motors automobIle,. It sh000 bours. this operation has geile1rally be4!l1 acc0IlIp8nied by nU'D!lelrGW! sbut- do-ilm.5 vilel:E! v'llriOl!llI cOOlponentll: (aeals. heat- ers. etc.) were cbtinSed. Table 4 provides itl.fo~tion 0:11 the testing eJtperleuce witb s:b:e ASK engines letlding to tM: HOD-I designs. Az indicated. testiug timas on any given unit Iilr€ tYllic:ally in the tens of hours T8fl8e. rMre 81'e se1l'eral reasons why 1MIl:'0 reliablll! oper,Elt:ioll bas not been ac1lieved l!Illd non~. in themBclvee. appear to be unsolvable udn@! ld6!!aUfiable tedmolo$Y. A study of &'!lto~Uve d~a-rlved SU;:'ling e~lH$ for station.:!lry applicatiens idenltified design ~ificaUooo toot: vould sl1o" a 50.000 hour life at re.mC',ed plt!l'!thll at:&dbutH of 11'1 SdrlUs tmsine v!lif.eh has not yet: Men satisfactorily ~il IItwlllted. Plm1l: PliriOO'~ Dt"GDl1:S - rna pl€1t'(;1)) St1rl1~ ~!i',t}~ halve cmly IKMn 1rt."*~t~ated~ &Ill a praeU.(>.8\l m~M;ter. fOlr c:oo!!ll\t'trcl&l a@1pU.c&- tiCNll9 0Wll:." tb~ 1l!l4lt 10 )'tMtn and toul Qli.lWn - 4tt1m!ls b1!l'lm ~ oa the order of $10 udlliom.. • YCQ' ~Gi; liIlIt~t for a I!MI ~ine dElWllotr' Wlimt PltoII'IiJ!i1l. 'I'i'J,e oUt08 of this tecaolCV abeel4 .. ~Lawed· t.eIdaa. iate coaeUeraUon tile 111d.ted reemm:ea .... t .. to Its 6mtlOfilleJlt • ... t of dae faYOrable aurtht.. (low ~:loDa. Iou- 1ItIIIIIII. etc.) It.rmt, hell· rea- ~l,. veU ...... tratecl 00 fRe piston eqUp!lM-mt teehcl at Suapouer. GeuenJl Electric. Sd 1l'I'I. IIov4mi!r. the CllIIIIldative opent:1q tililll of fna pistoa ~ :Ill the aili:e- ranp of taterest is aUll leu thaa· sooo h du not c~:r.e favo-cably with iIl1ternal ~h~tion ens1ue$ rel~tiVG to «':O$t. we1iht. an~ s1ze due to previously discussed factors. P:J.g.:n:e I 8~1tte.s tMi ranldll3 of die IIp-pl1- caUO\WiI fOil" develope;£ Stirlirltt ~ ~ 110108111:$. The top row in e.uh categ0lrY 1& the veipt.. This is the iIIlIport4!l'1Ce of t;lb;Qt tmrUeullll:f 6ttdbllte (euc:h as low: u4u1_a or 1 ... emu:) to the qpUc:atiOD. Tble ae~ rov till the tl8fl1lll_t of eonvQlmti_l ~ tIKtmolqy totMt. Blfltltc:atton. n.e ~r lefi; b.md a~r is the raw' aeo~ aivea that ~.Ml. 81l!d the lwer daht hIluld mOOM!! is t:be \lO.Iligllted IIcen. ~ t.bbd ~ is tlw 3Illse$S- IIlllilt of l't:11'11.. nalM teehlllOlomr ill! t:1ult ap~1clI\t100. The up'pt1:l.:' left lwlcl lli1lDhr 18 tn QlIl? e.eore 81"., t:ll"t ~!I .. the IMler ril,ht it:&nd ~ 18 the -iPte4 IKon • For both tU ctmlffttioul II\1!ItI Stt.dma eqltla tEllC!m.ol~ tM IICO ... 10 Mae4 CIC tile ~ •. Tab!e 4 Suuuary Of Acc:uIaulated Operation Tille For ASK ~ And Hean Operatin& 'l1fta To FaUure OPERATION HEM OPERATING TIVE TO ENGINE TIME ,AllURE (hrs) ASE 40-1 (NASA) 238.0 6.43 ASE 40-7 (MTI) 206.0 7.95 ASE 40-8 (Spirit) 292.44 3.75 ASE 40-12 (Concor~) 140.4 14.04 ASE 40-4 (USSw) 6134.46 91.56 ASE 58-1 (U5SW) 172.05 15.64 * All classes of failures, since initial start of the enqine. are included in the calculation of mean time to failure. This includes. for example. replacement of cOffilwnents due to ll"eSidual core particles in engine due to improper cleaning. burner bloller belt failur'e. cracked spark plug. etc, SOURCE: NASAllellii sASE Program, Reference engille that i:s best-suit('..d or is currently beiD.4t used in that application. the pedal!'- EIollnc(! of thesEI engines aSSUBe:s the "high qWlllity· end 0·£ currently available technology for conventionsl engines and the successful cOEpletion of ongoing developm,ent l'rogI.'all!IS for the Stirling e:ogine. The colU!u.1l labeled "totall~" includes the SUN of the w~j~bts (rov 1) and the sum of the weig1tt:ed scon,s. in rows 2 and 3. for convE!l'l- donal engine!! and Stirling engines. respec- tively. The (~01W\lD. labeled "engine score" is the sum of tb~~ tteighted scores divided by the SUfi! of the we:tghts for conventional engines and Stir11u3 'engines in rmts 2. and 3. respec- tively. The colWilft hlbeled "deossification spread" is tun differeillce bet1o!lloell t'te St:1v1t1l3 engine score and the conv0ntionl1l1 engine score. the IlJreater tbi$ numH~r. the better tho Stirling engine loob relative to a COill1entioMl .~t!31ne. the ramt:lD.ft plCOeess r~l.!b'es I!!lllTstillE mDflNUfiI jWfiiitlftl'liltu as to too :relativ(l)pedor- _nee cl'wI'Cacted.stic6 of both Inte~l COl&- bustlon am.d 5:dd1»$ agiooa. Making thd.® judg,eIIll:utl'l b ~licate·li by the l1mted operaUoul Cf:otp&dence vitb StidiD8 enginll.'S. The ju.dl&~~nts MdQ relative Ito con_tiO!&fll fill'IItit,e tf/lclm.olQgies ay;e cow;;istelilt uith the chanctedGt:i'clll l1etCill in Table 3 folt' r.~ -rescmtatlve e.i.\&t!l!llils in each catesory. This raMhiIi Pl'OC.tlS6 18 useful in hta;bUpUS\I _jor issues affecting the potential use of Stirling etlit1nes. Rowever. due to the highly judgaentllll nature of individual entries to the rankin.g process. undueilUportllllce shoold not he att&ched to liROdest numerical dHfer- enCElr' in t(ltal scores. Figul'~1 2 sU!!l\llarlzes the results of ranking pr()CeS5. There is a rathel.' wide range in the potentlal for st1r11"11& e'lglnes in the different applicatlon classes. For purposes of tb.i.G discussion the appHcaUons vere ~lvided into three cat~gories. NOT PROMISING ~ U~e. Eguil~nt - Application is not dependant on the attributes of the stirling engine fOl: success. Depends heaVily on factors wch all! cost. sb.e. IiInd "eight in Which the stirling engine does not fair vell. iKl paral1'~l develo~t of the tech- nology. I!!du.!S!!al~~£. - Tiler-II. is tl rela- tively _11 Nnet v~dch Is l'ellsonably _ll-l!!elNed by conwenU.onal alteltQ./jl.tives. a1 thoutgh ~iti'r.a attributes of StirlUIg e1lf:jiMS are potlrnt1ally ilIlportl!lllIt in these appl1c6ti_. !!li~...!l:!i6:t .p~ - Alma .. relatively _11 _rut w:tb difficult (~ttnl!llve and t:ilJli! C:~h1I> certUlcetl_ pnx:dures (Jdl1tary I1p;!1el!l) .w.d cot\trol ntqui~tQ. Roftvelf. cost DI)t 8@ ed.tieal ni'd adV4ft~ of StirUl1\SI ~iMf; Are 1uIpow:un.t. ill th1a II!l'PUcaUO cootrol .yst_. and. in __ uses. fuel. tIDke. not just the prhle Cl\l)ver or aecMmJleal part of the .,.8tO. 'CIr each applieatioo cl&!il8 the,re are a IlU!IINr of StirliDa enas.- c(),f:isurati01l8 which could be selected .. the basdine desi8D. For eltltlllpltt. eitber free puton or kinematic St:irlhs enaines could, 1n prinCipal be used in all applicatioo classes. In thls section. tbe ~line til5h1e clestgn selections are consistent with tbe aBpbaeis of current prearm-· The coneeptaal dU1gn8 sele1:ted _re: Rural Power Unit - 1 kM bot air kinemAtlc ens:l.Nt -ina b10waas fuel; Silent Pover Unit - 3 kN free piston ensfDe with l1near alternator; Aut06lDt:ive Derived Power - 55 kV U_Uc engi1le based OIl MOD-I design (propu- ls~~). and - 30 kW aut:oaotive engine derated for l(mger life; Statiooary Power - Scaled-up autcmltive engine SY8t-. l'igure 5 illustrates the desip of a cC'Jlll:19\lltchll heat pump system using an lIIutoao- the derived eq1ne. Table 5 provides a comparison of this design vith a "conventional optiOl~" using a Diesel engine. As indicated. the Stidins eq1ne wou.ld have significant parfo~ce aclvaotasea relative to such bJport;aat par_ters as efficiency. noiae lev.hI. aIlId cmissiO'lls _ cOOl:~ared to tbe alteraative arrana-.ent baaed on already d~str.ated StirltDa en&in. characteristics. However. the potentially favorable application places severe conatra1l1lts on ensine life (20.000. hours) and tbie-between-aaintenance requl~t9 (2,000+ hours) both to satisfy appliea1l:iO'll needs and to Met the cOIIIpetitiO'll pret«l'l1ted by an I.C.· en.he. As indicated in Tabl~ 5 these requlreM&Dts are still "To Be DCliiO!llliltrated" for Stirliuaengine systeDlS. IilltMI~. as idieated previouBly. SOI!le stWi1l0S have indiUlted that these 3el<'lla .y be acbi~l!& thrcm.ab operatiO'llal 4l'Id deGip IIOI:IdUiaU011 a'IYII/or deratina. The other con~Q;_.1 d@stpJa indicate equally favorable IIK>tefttJ&l for SUrl1n& ngil\es if lif. and reltll~ility ishl!.'S can be successfully re- sOob/lld. StbUq i;V EmiWofl$ NoifilJlJVel 3!). 100 kW 70 kIN 3O-4OY.. 34')1 Site Spa:ifit: Situ 5pgJcific I (Onlv LoeBI R,,· ... tlltion at PresoRt! ft,~int"'''nnoo In«'fOm. 3. o,..~l!dlni»Omp I!irId ~ at Some Adliitiansl 0)$&' l.oool-l_s St5IH.30111ltW" InM.m'Itly Low and Wi1I>in Raquirem4!nts FrOO\ Coolant; Minimal A.&litiO!'t4l Cmt TIlO' ~ Eold 01 Cost Range Prol:labIy AchiNlbte WIlhinRlIi'IgIt WilI.in AiIngt options, :such as size, weight, and cost may not be sl!rious drawbacks in most of the applications of priaaryinterest. lfany of the aore fa'101rable applications are now served or could be I;erved by relatively btgh cost ($100+ per kW), heavy duty engines. This provides a.Jc!!::ional incentive and flexibility in the design of suitable Stirling engine systems with rega:rd to engine cost requirell'lft1ts. l'abl,~ 6 qualitadvely su_rlzes the overall results of the study and identifies those cr:l.tical improvements in performance which Stirling engine systems IIlUSt achieve to be consistent with the broad requirements in each application class. The identification of key development issues assumes that ongoing activities are reasonably successful in achieving progrsaatic objectives. For exam- ple. it 'was assumed that the off design performance goals of the free piston heat pump programs can, in fact, be demonstrated, that effici~ncy projections for automotive systems will be lIchieved, and that automotive tech- nology could be scaled up to result in large stationary power units. With the.se as- sumptions. there remain several critical development needs which ~lre not adequately addressed. by ongoing programs. A cO'/Jllllon theme fer all ,Elpplieation clasf'cs is the need to emphasiZE: designs which are consistent with long lif'~, low maintenance or -:rati(tn.. The quantitative disparity betweL:_ the life requiremt,nts of allJ.ost all app.lications of interest and the engine durability d~nstrat ed to da1te is very large. All applications, except autol!lOtive and other light dut:y vehicu- lar, require engine lives in excess of 20,000 hours. On this iIaportant issue, the require- ments of the automotive application are relativeJly II!{)dest, being only about: 3500 hours. If these life and reliability goals can be demonstrated without large cowprcuises in other required features (such as high effi- ciency) or large increases in cost, the Stirling engine ",ould be a highly c01'lpetitive option in all but very light duty applica- t ions. On the other hand, without 2lchieving (or at least approachin!t> these life and reliability objectives, the other desirable attribut,es of the Stirling engine will not be sufficient to result in commercially viable systems. Also indicated is the need to coftsistent- 1y demonstrate high efficiency levels in order to satiufy application class requir"l!ooents. This is due to the fact that Stirling engines RUSt often cOlllPete with I.e. engines whicb can bawe l!ffic1encles ranging froa 25% for saalIer sasoline engines to 40% for larger low speed, Diesel engines. It will be important for Stirl:tng engines to show a distinct efficiency advantage to provide an inceptiVe to pursue ~ir development. This is especially true for autOIDOtive applications where lower Zuel COllWUIaption would be a major incentive to off-Mt bigher first costs (by as much .as 50%), and larger size and weight, These high efficiency goals are, in fact. state. goals of cmZOittg programs. The need to actuall! de!IIonstrate a consistent capability to .eet these goals is shown to eaphasize their ilIIgIortance. the illBportant development needs for Stirling engines, I.e., most critically to deuonstrate longer life and higher reliabil- ity, are common to all the application class- es. The ovecwhelming need in this area should guide future program initiatives so that resources can be focussed on addressing this critical issue. Present programs have, for tbe IJIOSt part, emphasized ~chieving other ililtpOl'tant operational goals (low emissions, l~r cost, etc.) and system issues with relat.ively modest resources directed toward tedulOlogy developments to specifically ac!drE!SS life and reliability questions. All the application classes share some c~ technical issues impacting of life and re1ulbility, namely piston seals, shaft seals, aue! high temperature cOlilbustor Iheater head subsystems. .The details of the technical requJlrements for those subsystems can differ signJlfic1\ntly between applications and system coefigurations. For example. low power level free piston systems can have l\ gas gap or hydrc~ynamic seals where higb power density, dMible acting, automotive ki.nematic engines re .. :lre sliding seals. Despite these differ- encel~, it appears that there is a high degree of commonality between the essential issues of life and reliability which face the different Sti.rling engine application class. As a result, Stirling engine develc'pment programs for obstellsibly different applicat-4.ons might have a high degree of overlap in their devel- opaent needs. This could provide additional oP9Qrtunities to more effectively uue li~ited res.r",urces to address basic technical issues c~on to a range of Stirling engine systems. --- ------------._._. "-._- Table 6 Suamary -- Stirling Engine Status And DevelopMent Needs APPLICA nON ClASS Simple Rural Power Silent Power Automotive and AutomotivE! Derived Engines (a) Automotive (b) Aut~tive Derived (c) Staltionary Power TECHNOLOGY STATUS Recent testing indicates good promise for simple fired hot air engine Testing of both free piston and kinematic engines have demonstrated most of technical requirements Testing has demonstrated most imjX)rtant opet'ating requirements and projec- tions indicate further improvements in efficiency Same as automotive Design stuciies and auto- motive testing both show promise of achieving most of required operational char'acteri stics IMPORTANT DEVElOPMENT NEEDS - Oemonstrate life in excess of 10,000 hours with low maintenance requirements - Improve efficiency to 15-25% range - Den~nstrate life in excess of 20,000 hours - Demonstrate capability of 2,000 hours operation without maintenance - Consistently achieve efficiencies in excess of 30% - Demonstrate life of 3,500 hours with low maintenance requirements - Demonstrate that efficiency pcojects con be achi~ved - Demonstrate life in excess of 20,000 hours with low maintenance requirements - Demonstrate life in excess of 50,000 hours - Demonstrate overhaul intervals in excess of 5,000 hours. - Demonstrate capability of 40% efficiency on range of liquid and gaseous fuels -···-------·---------------.......... r;-rr 1. "AutOlllOtive SttrlinS lII&ine Developaent. PrOlrUlil - MOJ)-'l Stirli1l8 Enatne Syst_ Perfor.aance." 1". DowdY. preseDted at Automotive Teclmology DevelopM!I1t Con- tractor Coordilltatlon lleeting. Iff! Report No. 81 AS! 224 I'll 17. October 1981. 2. AutOflIDtive StidiD& £nBine DeYeloio:llent Program: Quar'terly Technical Progress Report for Ped.ad: Januaryl-March 31. 1981, MTI Repolrt 50. 81 AS! 21] err 12; NASA Cr-165393. Augnst: 1981. 3. Design Study ~If a fine_tic Stirling Engine for Disltersoo. Solar EleCl:rb Pover Systel~s: Unit,~d Stirling of Sweden - Final Report; ~~SA CR-159S88; 1980. 4. "First Phase 'resting of Solar !berMl Engine at Unit:j~d Stirling." W. Percival. B. Melving; prElsented at Annual Parabolic Di~h Solar Thermal PrOiraB Review 1981. sponsored by J~~t Propulsion Latu •• S. ''Test Results and Facility Descril'tion for a 40 KilOliratt Stirling Engine," C. Kehlll. J. Calrelli. R. Walter. NASA Levis Research Center. NASA TH-82b20. June 1981. 6. Stirling Entin!!'.!; C. Walker. Clarenson Press, Oxford, 1980. 7. "Stirling Powelr Conversion Unit Continues to Keet Goals," POTS Highlights Vol. 2 No. 2 by Jet Propulsion Labs lEor DOE. Apdl 1982. 8. ~~ holt USA t.ruI .. search Cater 1a pl~1:a1:100 to DOB. 9. '"The Poteattal of tile PIdlips SUriiDa Itrt&fne for l'ollution bRetton aDI! IlD.ersy CcmaervatfOlil.· &. 1Ja1jer. C. $piat. pt'Uate41 at ~omI SJ'I!BP081_ 011 Low PollutioB P_r S,..teas DcneIOJlUll!Gt. orpniHd by COHIl1tt:ee on the Cha.llenaflls of Koden Society of the MAlO; lIcweiIber 1974. 10. '"Des1p of It Low pretl8Ure Air Iq1De for thl" World Use." J. Wood. I. Cbapot. L. PilmSVick. SWIpOwer. Inc •• 17th U'.CF.C hoeee41D&s. August 1982. 11. PenODal ~icationlll with Sunpmter. Inc. 12. "V160 StirUq Engine ••• For a Toul Energy SysteR. ft Stirling Power Systeas. presented at 5th Iaternational SyEpOsium on AutOllOti.ve Propulsion Syst_. April 1980. 13. Allt05lOttve StlrUn& Ensue Developamt Prolrau: lluartedy Technical Progress Repon for Period October I, 1919 - Deeeaber 31. 1979. NT! Report No. 80 AS! 116 Qr 7. NASA CI-159827. Hay 1980. 14. A Conceptutll Study of the Potential for AutOMOtive-Derived and Free-Piston Stirling Engines in 30-500 Kilowatt Statiooary POIIl'er Applications. A. Vatsky. H. Chen. J. Dineen, Mechanical Technolo- gy. Inc. KTI Report No. 81TR38, NASA Repon Mo. RASA C11-16S274, Hay 1981. ... ., .. :4 •. ~_' ,'-- .. Automotive Stirling Engine Development Program Overview and Status Report The AutOlllOtive S'tirling Engine (ASE) Develop- I!ellt Program has been under contract from DOE/NASA since March 1978. Four ~ I engines have accumu- lated more than 1338 total test hours. One of these engines was installed in a transient test bee! (TTfI) wbere its tlransient characteristics were evaluated. Thislccomplishmroposed design cbanges were eval- uated against the baseline cost established from the Pioneer study. The follOW'ing material substi- ~utions reduced 1the cost of specific components: o Heater head tube lIIaterial changed from Im.:onel 625 to iron-b,~se CG-27. • Gas cooler tubes material changed from stain- less steel to phosphate-coated carbon steel. ft Preheater matrix material changed from Sandvik 253!lA to A.rmco 12SR or 18SR. "·urther, several design concepts ,.ere· incorporated to reduce the RESD manufacturing cost: @ One-piece eq~lal-8.I18Ie cast-iron V-block o Perforated plate gas cooler e One-piece pis,ton dome and rod assOOlbly o Balance shaft, eliminati.on. Tabl", 1 su_,~rizes the Itlanufacturins cost reductions asscx;i&ted with each of these concepts. DWNSlZED IIESD STUDY - lu reviewing the requiroents fc,l[' the do!ffiSized RESD, it was cm1cluded that el 2250-1b curb-weight vebicle with an ellf.ino ~rtmmt equal to • K-body vehicle tiOuld 00 used. The study results slwoled that a V-dri~~ or U-drive four-cycle Stirling engi.ne could 00 desigued and pack8&ed to perfore in a s_ll-si~.a vehicle while lOOetbl8, Uld excElliNiinti; proar- objel~tiyes. It preUainary cross soctioa. of a cIoirDsi%.~1I4 ltEStl is shown in Fi&Ure 3. It _jor design concept utilized in the dONJlSiaed RESD was the use. of an annular neater head as opposed to the canister hea'ter head used in the ~ I eDgine and full-size RESD. Fi.gure 4 shows tb.e profile of an annular heal:er he.ad with one quadrant relllOved. Note the COlllpllCt. sisple construction as Cm __ ~. -!! GlIlII 8M ".~ ----- --'j Fif,. Downsized RESn Fig.) Canister lIeater Head FYII FYea "'113 "1M "~ . ;, . ~...a_II~(IIUi!I I _'~ ~ lIQd t P'fOClYJlemellit """'~T"'" I -.~ I -.~ .. I .. ,Im-, '." "ll'4'~·T"'* I -~.,.~. I _I~ l- I I I _'''-II YIlOIl'r,.... .. TCldI ! Ii!!,e'-A~ ... ! "",,~ 1-4 -.. __ I ....... ~ ..... _1-11. !II'$M VGII I _'.fli~ I ""'&1-8 "-_0l0II' 1-m 11 .. 1.1 .... '""- T ... - - Fig. 6 A.'>R hoof-of-concept PTogU.lll Plan ., • • • J!- 0 170 0_._ A. II J W I i m E , ~ j • o _I EqIIIa 0018 A_ .. AG6oJ v .. ~ 50 <> _WI CooorM1_"'" aI __ 10111 tW ~ - lef/$ Fig. 7 Engine Power Design Goals (Mod I. Hod I-A. ItESD) 0_'_ O_fl~_ .. _I-IIGd! ,,-~ ... OIAnlI-Ac:".,."g_,., ~ ~ 4r.... ___ ,..A..---..-.A_ ._...\, -L-. __ 50 411 42 III 1981 191!2 II!8ll IIl:\I4 lOllS 10044 Fig. 8 Engine Specific Weight Design (;oa18 (Mod I, Mod I-A. RFSO) --------,--------------- 13-"'''''''' j) _ , "-" I!sJa j~ "'.:4 t-.A Goat 'UII!SD"'_ ~1)U04"A(;4gt~E~'" 0 A 0 :M ___ ..t-----! __ ._~_l.._.___L_ _ _:'""'--' 11iG1 19>2 1!1fIJI 1!iIIU I~ 63IJ45 Fig. 9 Maximum Brake Net Efficiency (}!od I. Mod I-A. RESD) ~!od I (both projected and actual data) and the RESD. The figures sho..l cO!Gparisons for power. sp-ecific WElllght., and lIIQ.xill!lU!lI brake net efficiency goals and include estimates for the current config,uratic>n of the ~ f.-A desig,n_ T3ble 2 sUlOOIar i~es i;he ~ I-A des i&t'l goals. DESIGN CHA~S - In upgrading the current Mod eJl8,ine to the 'kld I-A engine. des ign changes were made that followed the proo{-of-concept progr3ID by cirliil.-iug on RESD te-cbnology. Part-P~.!'~j~izC\t!..~ - Since engines oper- &,;e at 10l!l: spe0ds dl.lrin& I!IOSt of IiIl autOli!lQt.ive driving cycle. the RESO had ~en optimiaed at part power to pltovide peak efficiencies 1t 1m; e1l&ine speeds. 1'0 GpgJ:ade the Hod I, additioaal p4rt-pCIIIGr optiaizatioo was Bade. This resulted in a Hotl· I-A cle81gn with s.aUer re&enerator end cooler cliaI~ra than those in the eurrent Kod I enaine. Tlds desip approach provided the Mod I-A with a Idjo,r weipt a.ncl coat benefit. ~erad'!I T!!!!p!rature - The current Kod I engine operated at 720ue. In uP&red!na the desilJIII. tllLe operatina temperature was raised to 820"e, a teaperature consistent with the RESD. This hi,ghe:r operatins teMperature provided the Hod I-A with the hi&her Carnot-cycle efficiency poten- tial of the USD. We~ - Since the weight of the current Mod. I enaine was above its 587-lb goeIl. one of the aajor desigrl sods for the Hod. I-A was a 100-lb weight reduction. Weight reduction was accOlll- pUshed bY' desipib& a Sll!&l1er diMl8ter preheater. reduced-slze heater head hOllSinp and lighter control syst_ components . !.!I!!!51Ved EfHcienc! - To illiprovc engine effi- ciency, lClsses were reduced in the seal and drive systElll/JS as; well as in the external awtiliaries. Non.<>trategic Haterials - One goal of the RF.SD, and therefore of the Hod I-A, was the use of low-cost ut.erials void of strategic elements. Design of the Hod I-A using nonstrategic materials in the heater head was a I118.jor step toward achiev- ing thi!> goal. The Hod I -A cylinder and regenerator housings would be cast frOlll XF-8l8, an iron-based material, rather than from the cobalt-based alloy HS-3l used in the current Mod I. nlbe material was changed (rOIl! the cobalt-based alloy N15S llultillMlt to CG-27. Table 3 C0lllp8l'6S the dramatic reduction in the' use of strategic I118.teria15 in the Hod I-A design to that of the current Hod 1. When cORpared to the llateri- als estinlatcs for the RBSD, the desip of the Mod I-A was consistent wit.h the proof-of-concspt. progru. Figure 10 eocpa.res the current Hod I with tM. lighter, smaller and IIlIOre powerful Hod I -A engine. The _jor des:i&n iIIlpxovelllents discussed in the above subse~tions are identified for reference. Table 2. Hod I-A Design G<>als _I _WI CIototoA IIIJU - - --- 1--- """ It. JZ~ -. - IIII.D 110''''* U as 15 .~ .. \'III 311 3l~ -, <&.II G.!i> Tablle 3. Reduction 1nSU'·atepc El to 0.25 gm/sec. This iOould provide the :-lad I-A \,;ith a significant gain in fuel economy. Several types of fuel nozzles .ere e ... ·aluat;"d for spray quality. Based on ~his e\·aluation. two fuel n07.%10s. a piiot,'d air blast. n0221e and a D~lalian duaI-:nifice nozzle ,,"ere selected for furt.her evalu,nion in a free burning r4; and a coabustion performance rig. TIle free burning. rig t.est compared the ignition and blowout limits of tbeStl tTolO noules to the limit.s of the current Mod I fu.el 1l02:l!le" !:loth experimental nozzles de.mon- strated an i;gnition delay ti_ less than 0.2 seconds. a J~, itaprovement ovel~ the current ~od I single-orifice air-atOilized fuel nozzle. Blowout performance of these two nozzles was also satis- factory, and occurred in 4 fuel flaw range of 0.1 to 0.25 sa/sec. As a result of these tests, the Delavan dual-orifice fuel nozzle was selected for the Mod I-A engine. Figure 11 compares the s£4l1- er Delav~m fuel nozzle to the larger single-orifice fuel nozzle on the current Hod I engine. Mod I CT821851S-11 SIngfe Oriftee AIr AIomIzed Fig. 11 Fuel Nozzle C03parison ~ATERIAL/HIGH TE~PERATL'RE DEVELOP~E!>.T - For the RESD to meet its desigl\ soals, the hot engine components must be capable of reliable and durable operation ,n a heater head temperature of 820°C. Further, the low-cost casting alloys used as heat- er head materials must be capable of operating at this high temperature. Since the inception of the ASE Program. the development of low-cost casting alloys has c::mcentrated on eliminating cobalt-base materials (HS-li and SISS mul~imet) in the cylin- der and regenerator housing castings and tubes, respectively. After considerable screening, the alternative casting materials to HS-ll were reduced to CR.'!-6!l, XF-8l8 and SA-Fil. The a 1 ter- native tube materials to :\155 multi~et _ere reduced to: Inconei 625, SAl\ICRO-32. !Zn!\72 dnd CG-1.7. Although the deve lopment effort cant. inues to obtain fundamental des i8n dULa ')n these mater i- a1s, actual engine tests were .lIsa considered essential to determine oxidation effects. There- fore, a 1'-40 heater head was configured IOiLh different casting and tube materials in eaih quad- rant. The heater head ",as placed in a p-.. O engine lllTP-"O) and tested under cyclic load at S:OoC. The matel:ial comhinat ions for each of the four qUljdrants in the heater are shown in Table 4. Spdre heat,or quadrants IOere available in case of failure. After 1434 test hours. t.he engine w"o;; st.opped due to repeated fai lures in tho 12R."72 t'.lbes. TtlbeS in the quadrant containing 1:.'R.'G2 are ~ing replaced with cobalt-base S155 multi.at t."'>in8 and tests "'ill resUlllc to'.'3rd the &oal of lltvv houn. The test cycle was set up to subject the beater head to increasing pressure and cye lie. load 1n order to accelerate fatigue and creep d~o. Pressures were increased to hi&her levels every SOl) hours, until failure WAS expected near the 2000-ltour test point. Table 4. BTP-40 Beater Bead Quadrant !Caterial Corab:l.nations ~No. ~-- ~~ ,....~ 1 HS·31 ~625 2 CAM-50 San!cro-32 3 Xf-818 12RN72 4 SA-F11 CG-21 L-. __ MOD I ENGI!\ETEST PROGRA~ Four Mod 1 engines are .~urrently testing in the ASE program. As sbm;n in Figure 12. a total of 1338 test bours have been accWDulated. Engines Nos. 1. 2. and 3 were procured and assembled at USAB. "hereas Engine No. 10 I"as of U.S. :ftm::fac- ture and assembled at 1'fI'I. The nUll'lber 10 was assigned to the NTI -assembled engine tl) identify it frolil the three European-manufacture/USAB- assembled engines. The manufacture, assembly and test of Engine No. 10 marked a distinct demon- stl"ation of the level of Stirling engine technology transfer to the, U.S. During the procurement phase for Engir.s No. 10. IIlOre than 30 U.S. vendors participated. Engine So. 1 has accumulated a total of 613 test hours. After an acceptance test with a new digital control. this engine was shipped in early Februar)' to AM General for inst:a11ation in 8. LentJll vehicle. designed to serve as a transient test bed (11'8). This installation was completed by the end of !'lay and Ithe initial testing began. Figure 13 shows the TTB insl:a llation. This installation helped to Blchieve a major program milestone by allowing the l:ransient characteristics of the Moci I engine to hI' evaluat:ed and Ilccomplished on sche- dule at t:hE! end of Sept:ember 1982. Cur.rently. Engine No. 1 has logged 92 test hours in the TfB. 369 starts (124 in the TTB) and 619 miles. Three separate Constant VolUlOO Sampling (CVS) t:ests were I:onducted on the TIS. Results showed repeatabilit,y and fuel economy consistent with prediction:.. ac and CO eillissions levels met program gO'lls and SO er.Iission levels also cO!!!pared fs;vorably wit:~ predicted levels. The exhaust gas recirculation (EGR) system used in the current Mod I gives NO lev~lls above t:he program goal of 0.4 grams ~er 1~i1e. With further co~bustion system deve1o~nt in the ~od I-A engine. this goa! IOill be Illet by virtue of t:1Ie higher mile'lge predicted for the RESD as ccmpared to th .. Mod I mileage. Engine ~1o. 2: has remained at USAB, where it has coopleted a series of dlevelopmmtt tests 8!ld accumulated a total of 425 test hours. This engine was assembled initially as a basic Stirling eU8i1\6 (8SE). A BSE, sboom in Fig,ue 14. does not h~lve a cont,rol sy-st_ and auxiliaries lIoWlted on it. This c')ufiguration prov:lded the c8p1lbility of measuring en&ine potier and efficiency without the illterference of these systeu lOSSf):s. Engine So. 2 "'liS testeo to evaluate an !:GR coabustor 5yst_. ~~> This engine vas then reconff.&ured as a Stirling Engine SYl~tee (SES) to include all cORtrol system components and aUXiliaries. F:!pre 1S shows the Hod I engine configured as lID SES. The data obtained frOll) the tests performed on Engine No. 2 provide back-to-back. comparisons of 8SE and SES power and efficiency losses. After an initial fWlCtional checkout at USAB. Engine .w •• 3 was shipped to ItTI where a complete functional test and an acceptance test were conducted. This engine is currently being reas- sembled 1St USAB to !.egin a 2000-hour endurance test progrmll. Engine No. 3 has accUlllulated a total of 261 test hours. Engine No. 10 COIlIpleted assembly at ItTI in August and has accUIIIUlated a total of 39 test hours. It is currently undergoing an acceptance test. Figure 16 sUlIIiIIIarizes the major program lI'IilestonElS accomplisbed durin,g the past year on each of the four Mod I engines. MOD I ENGINE HARIl'iIARE DEVELOPMENl- The ~od I engine program did encounter vari- ous development problems. Although many of these problems were minor ones and were solved during the normal course of development, the follOWing subsections discuss four areas where major prob- lem.<; occurred. CASTINGS - The Mod I engine assembly schedule had been paced by the delivery of cylinder and regeneral:or housing castings. The castings (Fig- ure 17) are finished machined and brazed with tubes to form a heater head assesbly. Two casting vendors Ilere established to supply these castings: Bulten-Kanthel in Sweden and Precision Castparts (PCe) Corp. in Oregon. 80th foun:!ries experienced porosity problClflS with the cylinder castings. During the casting process, the regenerator hous- ing cxpE!riexlced core failures Quring the waxing process. This was due to high loads on the canti- levered core "Wings" l:1itia11y, 8 high scrappage rate was experierced, which caused delayed deliv- ery dates. This experience served as input to the ~od I -A des ign. - --- . .- ... .- ._- I -.. - ... - Fig. 13 Nod I Engine Installat ion in Tl:ansient Test Bed Fig. 14 ~,d I Basic Stirling Engine Fig. 15 Mod 1 Stirling Engine System ~"--__ .---r------------------~ _I I ,_ A II 0 NT 0 I ~ I F 111111 A .. J J ! ! I ! "fI • ...,-..EJooiI'I . • ~~Spoo ... Fig. 16 Mod 1 Engine Test ~i1estones Fig. 17 I!f,od I Cylinder and Regenerator Rousing Castings A second development problem with the Mod I arose during the crucial transient test bed program conducted on Engine No.1. Engine No. 1 was configured with an electronic digital control. l:se of this e.t.ntro! great ly increased the engine's cold start t:rllnsient start-up time fro.r~ the slOloler start-up tUr£ experienced earlier with an analogue control. As ~l result. the rear rCN tubes and fins in the heater head expanded therma lly at a more rapid rate t,han Lhe inherently cooler manifold. This increase caused areas of high stress in t:he braze between the tubes and manifold. To relieve this stress and provide flexibility in the tube arrangement. the fins were cut between each tube rOl.' from halflo1l':: above the manifold base as shown in Figure 18. The ~od I engine was initially designed and built with a. co:nbustion gas recirculation (CGR) system. As shown in Figure 19. the CGR system recirculates a small percentage of the exhaust gases back into the combustor before these gases exit t.hrough. t.he preheater. The CGR system controls SOx emission levels by r"ducing flame t.emperature. Figure 20 shows both top and bottom v lells of the eGR combustor liner. Ejector nozzles in the cfrmbustor 1 iller are used to pump exhaust gases back int.o :he combust ion chamber before these gases exi t through the preheate:r. Early engine test ing showed large variations :In the circumfer.ential ten,peraleure profile on t.he heater tube walls. thus indicating poor mixing of fuel and :lir rosulting in ullstable cO/llbust ion. Further. during cold start transients. therlYl.al stress f~ilures ..:ero • '(I>"ri- enced in the support structures between the liner and preheater. Analysis shor.;ed that lehe lighter cOI!)bust.or liner expar\ded 1IlOre rapidly than the colder. Il101'61 massive preheater. This growth differential overstressed the support stnlctures. lea.ding to their failure. As a result. Engines SOl>. I 3I\d :3 "'ere retrofit with an EGR system that recirculates exhaust gases b.ack into the corabustor after these gases exit through the preheater. This mustor liner design. th0reby avoiding therroal fatigue failure of support structures. --.~- ---- -" ----·~~1 Fig.].8 Hod I Beater Head with Cut Fins Fig. 19 Hod I ~ustiOD Gas Recirculation Syst_ (CGR) Fig. 20 Hnd I CM!!bus·t.!on Gu ~\circulat101\ (CGR) Liaer Although the CGR syst_ experienced the above development prob LeIlIS , it is the IIOre efficient mystea and ther'afore is incorporated into the lRESD. The EGR sl,stelll has several disadvantages. First, it reductls bIOIO'er efficiency since inlet air tea:.perature is higher than 0111 a CGR system. Further, since illiet air contains exhaust gases, preheater clogging is more likely to occur in an EGR systeJlj. How'ever, the CGR system was deter- lIIined to require furt.her developmfmt before being (.onfigured into the Mod I-A and Mod I-B engine hardware. MOD I PERFORMANCE The Mod I engine character istics for both power and effici'!ncy, as measured on Engine No. 1 with a CGIt combustor, are shown in Figures 21 and 22, respectively. These data are compared to the Hod I performance predictions. _hen data from Engines Nos. 2 and 3 are compared to data from Engine No. I, consistency in pmier levels but. not in efficiency levels is evident. Figure 23 shows power levels at. t.he maximum working gas pressure of 15 !tPa for II 11 three engines. Engine ~. 2, when test.ed as a BSE, had an understandably higher power level since auxiliary losses were not. included. When configureJ ... it.h an EGR system, Engines Nos. 1 and 3 showed approximately the same power leve 15 as Engines Sos. 1 and 2 with a CGR system. Although analyses 3.re not complete. the improved circumferen~ial temperature profile experienced wit.h an EGR combustor could be cancelled by increased blower power. The earlier efficiency levels measured on Engine No. 1 hElve not. been duplicated in subse- quent testing on this engine or on Engines Sos. 2 and 3. Generally, the efficiency levels remain below 35% as shown on l'igure 24. \I'hen conf i:~ured l..-i th an EGR system, Eng ines Nos. 1 and 3 shOl>,.,d lo<>'er efficiencies than Engines Sos. 1 and 2 configured Io"ith a CGR system. Further analysi~; shOlo"ed that blo .. :er efficiency did decrease .dt.h the higher inlet air temperature associated .ith an EGR system. And-lyses are being performed on e.'ngine-to-engine hardware differ- ences t.o ,lcco~.r:.t !or lny C.aus~s fer ~ffic:~ncy level variation~i. !ion 1 TRA:-:Sl£\"!" PEII.FOR."1A.'\CE As stated, Engine So. 1 ,.·IIS installed in a t.ransient test bed to evaluate control, emissions and fuel "cancro}' performance. ;'he rfdnsie'lt rest bed is an AmeY."1':3n ~otors C')!"p. Lerma vehicle chassis .. ith 3. Chry"ler ",ide-, .c:Lio :;-speed auto· lIIIat.ic tranSMission wit.h lockup. a 2.73-:ear axle ratio, air conditioning. po<,;er steering and power brakes. Inert.ia ... eight. of the TIB is 3750 lb. Fuel eco,",-011\}' precic::ions ,.,"ere made for Engine So. I with an ~GR cC)mbustor systero using unleaded fuel Ill; 11,1 hp road load: G> t;rban ~ilea&'e: 19.1 mpg Gl His:hlo:ay ~ile.!ge: 30.0 '"'PI!. 41> COOlbined:1i l'eago, 22.8 mpg. 61 NOx _ission levels were predicted to be 0.84 gr8lllS per aile. He and CO emission goals for the program were 0.41 and 3.4, respectively. Table 5 summarizes the transient test data. Ii £ I Q. 80 70 60 SO 40 30 20 10 o o Hwd,....-aGD 720'C __ T~ SO'C CooIitIO _ T __ -... ~ 411 __ I'00I>'II 13MPa 11 MPa 5MPa IUM1 Fig. 21 Mod I Stirling Engine System Data Power Characteristics Hydr"1I"'~a..· 72Q'C __ TetflIl6rn1ure SO'C CoobnQ _ T .. "~ _Pt_ fU'!I ~ I'Ioc>Nt Poo<\1s O~------~~----~L------,--~lL-_------_'L-------~' o 3000 tOOl) 5000 Fig. 22 ~ Spcled /f'pm) Mod I StirliOR Engine System Data Efficiency Characteristics Q: Eo e 8 D. Tllble 5. Hod I Tr&nsient Test Da~a (CVS Testing) 80 70 60 50 40 30 - UtrbMCydo Run ~ .... 0.881.,., Ho. HC· 1 0.225 2 0.200 3 0.247 - "GmmPEKmOO i ·T~atWTI ··TIMlid a: VSAO C()* 3.43 3.27 3.:21 NO.* fRP'lII 0.96 19.9 0.90 18.8 0.84 19.2 x .1 EGA" 0.1 CGA" t>"lI2SESCGR" 0.2 BSE CGR" oe3EGR' 10 ____ ...&.' ___ J_-J........._..1od.-__ ..J o 1000 2000 3000 4000 5000 Engine Spesd (rpm) Fig. 23 ~od I Stirling Engine :,ystem Data Power CJmparisons (at 15 MPa Working Gas Pressure) X .1 EGR' 0611 CGR·· l::. e2 SES CGR" 0"2 SSE CGR·· a.3 EGR' Fig. 24 Mod I Stirling Engine System Data Effic.iency Comparisons (at 15 Kfa Workiflig Gasl Pressure) ....., ~""".'''' ~heI He" -6lF" NOa * ... EcoMmy( .... ) 0.004 0.28 0.75 31.7 23.9 0.005 0.25 0.62 32.1 232 0.004 0.40 0.61 32.4 23.5 SU~MARY This paper has described the major ASE program IIlccOIIlplishments made dur ing the past year. Time and space do not allow for reporting on all activities. The advances .ade in Stirling engine technology is moving ahead very rapidly. Improve- ments are being made in the use of ceramics for not only the preheater but also for the regenerator matrix. Such breakthroughs will have a profound effect on reducing canufacturing cost. Combustion s)'stem development is directed toward effect ive fuel nozzle designs With large turndown ratios. The succ,essful development of a CGR combustor system i$ i_inent. Pisr;on rings and main seals are continually under development to improve reli- ability. durability and installa1:ion simplicit;y. If the Stirling engine is to be adapted ~uccess fully to t;he aut;omotive mission. the control system must be capable of reliable and repeatable transient performance. Development is also focused on the 11se of an air flow meter and fuel flow meter to better mate with an automotive elec- tronic digital control to allow precise and rapid control of fuel and air ratios. A major program goal next year will be the assembly and test of the ~od I-A engines to demonstrate higher efficiency and 10\.'cr specific weights. ABSTRACT ~.~Iod I Stirling Engine, the f ll>"·Stirltng- Engine des·i~specifically for-au-tolnotive appli- cation, is ~uder ~elopment. at ~Iechanical Tech- nology . incorporated (~I) as pan. of the Departlllenl~ .. of. _.E.nlUg}:~spon"t.1red Autof!lut:ive-··Stil;e.- ,--UJag·~~in.~ __ USf..}·--·-P-r.ogralll. The initial 1 ( charac1:erizat ion of :he first 'lod I engine was 5!nce ~~lat t!me, devel- opment. e::o!"ts ha\"e :1dded s 19ni f l.cant st~3dy-5tat.e data 1:0 ::he des ign base, lS \.:e 11 as accomp I ished initial engine transient evaluation through fuel econ01llY t,~stin&. Relative to earlier P-.:.O Stir- ling engine-pc' ... ered vehicles w; ~hin the ASE program, fuel economy !l!iprovements of up to 50";, have been achieved ... ith the '1od I engine. An advanced version of this engine, the 'lod I-A, is curren1:ly in the design stage; analytical projec- tions indica1:e substan1:ial improvements in Engine specific Ieing pur!iued In the :-Iod ! devel- opment program. as "'e 11 as in the des ig::! of an advaT'..:ed ~!iod I engine, the '1oc I-A. ....- . Teslilng of the 'lod I engine has established p·,rforruau<:e levels during steady-state operdt.ion md has documented auxiliary power consumption. Base-line transient test bed assessments have demonstral~ed significant improvements in fuel econO!llY relative to previous St.irling-pOIoIered Automotive Stirling Engine Development Program Mod I Stirling Engine System Performance Albert Richey Mechanical T echnolO9'l Inc. inc~uded. The 15 '1Pa performance curve represents the maximWII available power level, and the 5 'iPa data provide performance indications at average operating conditions in a ~'ehicle system. The 1:ol:al engine-to-eng1ne power variation was less than ! k~ at ~ll power :evels, while the maximum power level demonstrated by all engines also exceed,;,d the min imum leve 1 es 1:ab 1 ished as the final acceptance criteria. Figure 2 shO'.'s efficiency le\'els attained during engine testing. rn comparison to power variations, the variation in efficiency level from engine to engine was greater. Engine # 1. dur ing final acceptance testing at Cnited St irl ing of S"eden (lSAB). shOlo'"d the most signiflcant devi- ation inefficiency level performance. Although II c: a. c: u.I 50 3Q1 ~""P' o &>go ... _t T_~" USA8 X ~.1 T,,_oIMT1 vehicles. nw..~-pre·~~t.t .. the results of these i:,,~.~--programs. and '''''<>je-4}\;S performance 10 .improvelll!<",ni:s achlevable in the ~:xl I-A engine.-,t .I .. ,."' .. -f / ENGINE CHARACTERIZATION DATA Figunt 1 presents poIOer characterist ics for the eng if LOS tesr'ld in the ~ I developlil1!>nt progra.m; for tho sake of clarity, only the n ~Pa and S ~Pa mean charge pressure levels are Ol~ ____ ~b-____ --J~ ______ ~I ______ ~ Q 1000 2000 3000 ... ,. Fig- 1 Mod I Stirling Engine Net Power the reas()n for this variation is not complE>tely understood at this time, three contributing factors serve to qualitatively explain the higher efficiency level of Engine #1: 1. This engine rar. with the initial vers ion of the c:ombustion gas recirculation (CGR) combu- stor, for which high-temperature spreads were measured on the heat~1C head tubes and working gas temperature. Although the measured aver- ag._ heater head temperature level was maintained equal to that used during other engine testing, the actual effectivp working gas 'Cemperat 11re could be higher than indicated due to t.he incomplete temperature coverage on the heater head. 2_ FollOWing steady-state acceptance testing, transient tests indicated the desirability of modifications to achieve more rapid changes in engine power during deceleration. This effect was achieved by enlarging the internal lines leading to the working gas remc.val system, thus incl-easing dead volume in tho engine cold spac.e and rb':;"lting in a lower steady-state effi.ciency level. (All other engines have sinGe incorporated the enlarged internal lines, as did Engine #1 for its testing at ~TI and for the Lerma transient test bed installa- t ion, ) 3, During the pe r f ormam:e spacer rings 35 final acceptance testing, engine may have been affected because above the regenerators became o Engtne 0' Testoo at USAB l( EngIne" Tested at UTI A EnglOe tl2 Tes~ at uSAB a E"9IM '3 Teoted al MTI + A.ccepumce entana ~ 30 ,.. '> c:: ., U ;:; IoU Q z 25 15 () ~----'---........A--..-J ___ •___ .IJ o 1000 2000 JOOO 4000 Engtne Speed ,rpm) Fig .. ) ~lOd I Stirling Engine :-let Efficiency warped, caus ing changes in hot space dead volume and altering flow distribution through the regenerator. I;ngine #1, as tested at !ITI, utilized an exhaust gas recirculat:ion (EGR) combustor, enlarged internal lines, lnd non-warped spacer rings. It should be noted that the performance of the engine in this configuration agrees very well with that demonstrated by Engine 112 and #3. Furthermore, the efficiency levels of all engines met or exceeded those establ ished as acceptance criteria. As m~ntioned earlier, high heater head temperature spreads were encountered dur ing the initial testing of Engine 111 with a CGR combustor (Figure 3). Due to the >:"igid construction of the CGR ,;ombl!s~or, warping of combustor mountin snd scaling hardwaz-e was also encountered duri g '..he rapid thermal transients of engi~~ starts. Tn~re fore, it was concluded that further CGR development was required and that EGR cOll'bustors would serve as interim combustors for the 'lad I engine. As shown on Figure 3, the heater head temperature spread is drastically reduceU with the EGR combus tor. Testing of an EGR system for the ~Iod I engine was accomplished using two engines to establish and verify an optimum EGR schedule fur providin~ acceptable emission control and engine performance ~ ~ .. co a. (/) .. :; ;; .. 0. E co ... 1:1 .. .. 160 140 120 100 0 80 :r 60 ! .. ., :r o 40 20 0 ...... ---"-- o 50 0 0 0 <> 100 0 .J. 150 eGA System Engone ., o o Fig. 3 ECR/CGR Heater Head Temperature Spread (1).* The performance impact of the selected EGR schedule is shown OICl Figures 4 and S. Figure 4 illustrates the degradation of engine power with increasing amounts of EGR; the se12cted EGR sched- ule is superimposed on this curve and shows a negligible effect 'on power level. Similarly, Figure 5 shows engine net efficiency degradation with increasing EGR and also includes the selected EGR schedule. The EGR impact at the maximum effi- ciency point is small (0.3 percentage points) and, at the average opera·ting point, shows an efficien- cy degradation of 0.5 percentage points. A comparison of emissions characteristics of the EGR and CGR combustors showed a dec=ease in CO emissions, with an increase in SOx emissions level; hydrocarbon (HC) emissions were negligible with either combustor. As illustrated on Figure 6, the EGR system provides improved CO emissions characteristics at the higher fuel flOlO rates. The NO x comparison (Figure 7) shows that emissions are higher with the EGR combustor than with the CGR combustor; nevertheless, based on current Mod I fuel economy levels. maximum N~ emissions levels of 1.0 g/mi "ill be met with the EGR system. AUXILIARY P~'ER C01\SV~!PTIO~ Testing included documentation of Basic Stir- ling Engine (BSE) and Stirling Engine System (SES) ~ ; o 0.. 4i z OJ c 0. c w o ._-l __ L, __ .....JI..o. __ A..-__ .J.----J o 10 2.0 30 .eo 50 60 EGH\%) "'.,. Fig. 4 Effect 'of EGR on Power (15 MFa) *Sunbers in parentheses indicat.e reierences at end of paper. --.- perfonaance on the S/Ille engine. The difference in perfor.ance level between these two configurations rapresents the power consumed by various auxilia- ries. Figure & presents the measured power difference obtained via tests on Hod I Engine #2, compared to thE' summation of measured power consumption obtained via rig testing of the indi- vidual auxiliaries. The total auxiliary power is the measured difference in power output between BSE and S£S tests .. The auxili~lry rig tests measured power rcquired for SES steady-state operatio •. ; the following operating conditions applied: 1. Hydrogen Compressor: short-circuit mode 38 l 36 >-(J c '" 34-U E w operating 4i \\""'" Finol EGil Z 32 ,~hedule OJ c Co c w 30 \ \ \ \ 20 30 EGR (%) in the 1500 rpm. 15 MPa 50 60 Fig. 5 Effect of EGR on Efficiency 10 0 0 o roCGRl l~~ ~o 8 8 o re> ~.llIx'lgx 1 2 0 l(~X I 3 Fuel Flow (gIS) o It I #. 4 5 ... ,. Fig. 0 CO Elrdssions - ~Iod I Stirling Engine 2. Combustioll', Air Blower: nominal operating line controll~1 by air throttle setting 3. Atomizer A.ir Compressor and Servo Oil Pump: atomizer nir compressor discharge controlled via press~ure reI {ef valve ,~s in engh.~ opera- x a z 10 x 8 6 4 2 C) x x rxEGRl ~ o '--__ ....I--, ___ .l.I ___ ,...!_ 1 _---' 4 5 o 2 3 Fig. 1 6 5 - 2 • 1 - Fuel Flow (g/S) "'". ~o Emissions - ~Iod I Stirling Engine l( --Q-< .. - Total Auxdtar), Power ~-E"9"wll2 -- Fig. 8 ~d I Stirling Engine Auxiliary Po!trer (15 MPa) .".. 1:iga. Servo oil pIAIp provicUna £1011 to cClfllll)eftsate for syst_ bypass leakage 4. Alternat;or: providin& power for electronic:. control 5ystea. The COIIIpar1son of total measured auxiliary powel' to the sUIIIIIlation of individual component power requirell8llts reve6Is excellent agreement (see Figure 8), with a difference of approximately o . 7 ltV at. I1118X:iIIIuIa power. ~"'GI}..r: l'TlI.IZ.\TION RATES SinC~1 the start of the Mod I dev~lopment progr_ io January 1981 through September 1982, '1338 hours of tes~ing have been accumulated on four engines. Figure 9 presents this test experi- ence as au average monthly utilization rate, and compares it to the utilization rate achieved with the P-40·-7 Stirling engine at nI' s facH ity during calendar year 1981. It is noteworthy that the avprage utilization rate for the ~od I en6ines, even during ~he initial familiarization tes~ing. is 50~ higher than ~hat achieved With the P-40. I> IIIOro mature engine. The ~od I engine design changes, directed at improved reliability/ operability, have resulted in a decrease in ~ngine downtiue. TRA.'\SIE:\-r TEST !If.!) (TIS) Ft"EL ECOSO~ ~od I Engine ~l is dedicated to the devele?- ment of transient systems .ithin the ASE program. To pro\-idle t:his capability, i~ has been inst31:ed in an A.'1G Lerma Transient Test Bed (TID) for op:i- mization of engine/vehicle system characteristics and deveiopalellt oi the variOUS englne contro~ systems. Performance improvements real iz .. d through 'this deve lopment process can b" measured ! r 20 ,. ~ ~ 15 ! 1.5 J ~ = i 10 :;:) f I Cl!' ~,,,,, .... Fig. 9 Ifod I Test ~erienc:e ..... --- - by improvements in vehicle fuel Elconomy; hence, an initial TTB mileage evaluation was established to provide the base line for this tElsting, and exten- sive documentatio~ was acquired to enabie assess- lIIent of any sy~itet:l changes. First, Engine #1 was fully characterized in MTI's test facility prior to installation in the Lerma T11i1. Emissions data and standard engine performance data were recorded and ut i lized te> prov ide base-line eng ine maps for comput:er code assessment of veh icle mileage and comparison to any engine t:IOdifications accom- plished during development. (I;ngine character- ization "ill bE' repeated in the event significant modifications ,Ire incorporated.) Following char- acterization and installation. base-line Constant Volume Sampl in~~ (CVS) tests were accompl ished and analytical mileage projections wer>! established utilizing ~lTI 's vehicle simulation code. Three separate tests, each consisting of a cold start urban cycle and a highway cycle, were conducted. Test results to date, along I-;- ---;, 1 -1311 ,..,. v_ 021 U ' ..... OolS 12 -- G02S 0_ 026 U - - ., . ..,. ...... _----»WlIl _ - ... ..,3 ..... _ OllQ '811 .Ii' nil Oet 'IIZ 114 :r.u ooe O~ 08 0211 oro .. 3 11.' 7.15 cap ... lOO D.' ..,. If! ~D I -A P£RF'()JI}lM'CE The Mod I -A engine design (2) is aimed at providing ulproved performance levels relative to the ~od I. ~md also at continued proof-of-concept demons~rdti(m of a projected advanced ASE desi&Q. known as the Reference Engine System Design. In addition to> the normal design goal of improved cycle efficiency. the Mod I-A design effort is addressing the energy consumption losses deter- mined by th,e Mod I Lerma system testing. Table 2 summarizes Imalytically projected improvements in the ~od I -JL engine and compares them to current analytical modelling of the Mod I engine. Several design changes (see Table ) contribute to t.hese maximum power and efficiency level improvements; these include: • Increased set temperature to provide improve- ment in cycle efficiency • Redesign of heater head and regenerator to achieve improved castability and more optilllUlII part power performance ~ith minUmal effect on maximum engine power output • Incorporation of rolling element bearing drive unit and improved seal designs to decrease friction. losses • Incorporat ion of new fue 1 nozzle system to e 1 iminat.e air atomizer compressor and associ- 3ted power loss. , 25 J" " ModI Ce@ 0. ..... GTTB~ ~ 0 §. ~ ~ ... , ~ ........ i .......... i ..... --u 6. "', ... ~ ... - ... - m...t. I .I b_J 3ClOO 3500 4000 Vebide Test We9tt (~ ... ,.,. Fia· 10 Ve.hicle Fuel EconolllY CoIlllp&"Cison -' ; ····"·~"'~~f .... , ';:;'~:~"i , URBANCVClE HIGHWAY CYCLE Fi.g. 11 Lerma Vehicle Energy Consumption - Table 2 Hod I-A Performrulce Projection $UPa 2()00 rpm 1A'~rll!l" ()paoatinll - y) PoInI) Pm_ NlII Pooler Nd~ t~E~ N\>1..."..,. UoIE~ ~w ..... "0,11\11 I\)lhp _1-11 l:lt>-_~I -- tru!tI kW ',0.2 kW 211.9'1& +2.7 pi ~7fM +3.07 p& 12.57 kW +2.43_ 3304v. -pi 4.4 -2 73 ..... In addition to these st.eady-st.at.e performance improvement.s. a reduct.ion in cold-start. penalty is projected as a result of the lighter-lOeight.. rede- sign~d heater head and external heat system. It is ant ic ipat,~d that il 1 r:. reduct ion in stored heat ,"hich translates to a 0.5 mpg urban mileage improvement.) .. ill be achiev'ld .. ith t.he ~od I-A design. The overall project.iou for t.he ~ I-A eng.ine is that comb ined fue 1 economy wi 11 ioprove approximately 3 mp& or 13~ relative to the current ~ I system .. Tab14~ 3 Major Improvement Areas for the Mod I-A Stirling Engine System 1'1 A~_""'" A ............ ., T ......... $ 'q ., "ApI ~ -2 "~pI ricfionL_. +.2 +O.Ntpt " AIi>Mlnr ,. +().$ +O.3Wt pi --"--- .... REfERfSCES 1. Farrdl, R .• "~od I Stirling Engine Emissions .. ith Exhaust. Gas Recirculdtion," !'lechallical Technology I!lcorporated. Aut.omotive Tec.hnolo- gy ~velop!l!ent Contractor Cooroination ~eet. ing. October 1982. 2. lfoodysson. I.. "Upgraded Hod I SU.rHng Ent,itl6 Systes Design." l:nited Stirliq of SJieden, AU'tClmIiotlve Techno!ogy Dev .. lopaent Cont.ltactor Coordination ~till&. October 1982. ·Upgraded Mod I Stirling Engine Design (Mod I - A) IMlROOOCTION nm·'l!IOf'-k-.~t"tetilLttti.s-.~-i-s·~f the ~.~]opmel1t. ·~-wtthfn tfre I ~u!t~-SU.lelill§...Eng.i.ne.-hg~. A fi rst r geMration engine. called Mod I has been developed within the progt'~ and has been under test since tile beginning of 1981. To date foul" engines have been built and tested for over 1300 hours., \'I'ilese e~li pes now serve as basel i fie experililenta 1 engi ReS in the p1'ogram. The lJInSt.Qwe .., ..... ASE~(MSc) I..InhIld StiItint AD an engine block lIIhich in tum is placed on the ct'ank-case. The displacezent is 123 cc per cylinder. The crank-case contains tuo crank-shafts which are syndtronizwed and coupled to an output shaft by gears. The reef procat1 ng parts are of a cross-lINd type desiga in order to achieve a linear piston-rod IIOWllleRt which IDllkes it JlOssible to efficiently seal off the volU\'lles containing the ..orting fluid. (Refer to Fig. 1.) upg,·ading of .Cod I will prove technologies In des.igning for autClllOtive application. eiiOOdied in 1~ Reference Engine Systeill Dasign high pt)We1" to weight ratio is an fll/llOt"tant (RESO). . objective., This has been achieved lMinly by The paper' highlights desi~lfi improvements in use ofalUi1in1um in .ost of the cold parts of tile first ph.lse of thi s ·Proof-of-Concept.· the eng1ft1! and by having only one Main objecthes for the present design. called regeneratol"/~s cooler unit per cylinder. The Mod t-fl. havE~ been: IiM!Chanical integration of the engi_ is ~ 1l11provE~d power and pm.'eV' density , achieved by the use of tie-holts beb!een the (specific wight) .v .... J _ .. -------...'v heater head and tOO crank-case. L il'lproYI ROO -----~_ H;TOii ROot> SEAL MO\ISE CI>OOS I«AIl ~l5MUP--·------·----·-__t ~--= ... ~=-·---·1'U£1.1NJ£C10!,! ~-.. ~~~~!~~r_-~~~ Fig. 1 --- Fig. 2 1'1 There1Fore. and .lso fos· taproring 1J"el1ebni1~ and deslcmstr.t~ng endurance and cost reduc:tion potentials. all engine sub$Ysteru; have been upgraded tn various ~s. Table 2 slllmilrizes salient Mod I-A advances. To reduce hardware rislts. Nod I and Plod I-A subsystelu are also desigrM!d for fnterchaft!Jeability • ENGINE DE!)IG14 DESCRIPTION .• EXTERIW. REAT SYSTEM The Ml)d I-A external heat system is the 'it:llile type as the present for Nod I. It has a counter-rlow recuperative air prelleater. The heat exch;u~r matrix cons"ists of a 1 arge number of thin plates. sealll welded together. (Refer to Fig. 3.) The ~!W design is less bull\v since til pret~NlIter i s locaWd c 1 OSCII" to the heatel· tube array. M1:il"e I~fficient insulat·lon is used to further rll!doce ollerall size. Air lAnd exhaust gas M.'!lniflolds. optimized for flO'.>6 distribution. are more integrated to the preooater. The e:ntire unit has also been rede IOOre tolerant to thermal transients. Internal seals and those at the botto&lll plate and upper cover should be more reliable. System assembly is simplified by using clamping ri ngs instead of nl.mlerous bol ts aroulld the perirmery. The cover is shaped to allo~ combustion gas recirculation (eGlt) or exhaust gas recirculation (EGIt) type cowbustor. Both types are under experimental evaluation. However the current design calls for an EGa system. ENGINE DESIGN DESCRIPTION - PREHEATER The preheater plates consist of a corrugated part in which tne true counter flow occurs. Both ends are extended to fot"l headers for the air an" combustion gases. (Refer to Fig. 4.) The dhl:WS i ..,Mt~"'Y ·./lII'tot>GfI_fI'WIJI,l I ....... ~hJoaOclt~ ~,,~: • ~.n:su. c::cwen ":iOItIe'tlbM ,~~ · -- ie lJO"'!ff.......... i • ~_ItlIe..... . ~I~bt i· IliItWIICQnUI) .... 1 ___ +_.···. __ ..... ·_...;;.,_ ;--;;;;;-~--4-•• " .. ~--.-. ~~;;;;;;;.--' .... .;;;;; -.- .... - '\ftQa.nt~......." . ~S~ __ 'Ma-f(:iIIIr~ "'1IqI~ ~IO •• .()e.W~ ~.A@....~~ .~ ... ~ .~,~ ~ ~ O«<"4X.ll""'O~ ttfo-fIt'IiI. ~o-,.,.. p~ .~""""''IINI'' .~(& .. , f>o$lOl>"""QIt.A:'-'S ~I 1---.-1f·--------·--..+----·------- .---.------.~.---------- - -- • ~'ifC~ • Cl\¥/\ 10M (Ct-c>lt ,.t;on-1Oo2J, Incb/)ll'~J/"1 ~ -CI·(I~I • .a.t~"""T>I'f.~.. • ..... ~~ .. ,s • ~~.\lI!!I"IO • ~.Gf\j""""O~ --91"*" ~'Il~ ~ •. _- _________________ • __ • __________ ~~~O-~~~ __ • __ ~ ___________ _J Fig. 1 Fig. 4 Fig. 5 tJ ·------·-------1 -- - ·-····'~l ; J Fig_ 7 Fig. 8 ENGINE DESIGN DESCRIPTION - HOT ENGINE SYSTEM The stirling cycle heat exchangers (heater, regenerators. and coolers), have been reopt1111Z!ed for automotive part power conditions with increased operating temperature, 820·C instead of 720·C. This has resulted in reduced dimensions. especially for the regeneratorlcooler unit. The t~rature increase gives significant efficiency improvements. In addition, reduced size hot parts ghe less cold start penalty. The resizing also gives other benefits like lower wei gilt and thereby reduced llIanufacturi ng costs. In ol'der to further r4~duce manufacturi ng costs, the heater head has been designed for low-cost non-strategic IMlteri al s. Therefore the cych! optimization has been itet'at.ed with a thorough stress analysis. Relative mat.erial costs, a1l10y composition, and the stress analyses logics are shown 1n Figs. 9 and 10. Selected materials are . tubes: CG-27 for low chromiUl'!'l content • ca~.tings: XF-818 for weldability (repair) Of CttJurse the selection is based 011 a wide range of criteria and the properties r~ntioned are only special adVantages for each material. In ~edesigning the cylinder and regenerator housing, special attention has be€~ paid to imp,'ove (i nvestraent) castabil i ty and it is believed from vendor consultations, that the present design is much better than the original for Mod 1. . Heater Head - The Mod I-A heater head has retained the conically involute shaped tubes and one cani ster regenel'iiitor per cyli ooer. Involute· shaped heater tubes with a 90 degree s~n means that the milnl fo 1 ds can be located close tilt the center of the cylinders and regenera:tor hous i ngs for a good work i fig gas f1 ow di s;tri bllt i on. Ttl; s heater tube geometry .also gh'es a constant gal> along the tubes. which N!sults in a good outside flow distribution and heat tr.lnsfer froo the combusti on gases. (Refer to Fig. 11.) The Nod I heater heads btere ma.(k wi th Hilynes Ste 111 te in the hoys i rigs and wi th Multi~~ in the tubes. The NN~S~ gil for 1 ess costly i ron base alloys .lm:t elevated operating tefIlperature (820GC) has also allowed for other ililpl"OVements: a lighter flal!le shield. Simpler insuloltlon cover plates, che4per surface extensili)n fins. and TIC instr'tlll1!entation OR the outer s trai gtlt PfJIrt of tht' tubes. (Refer to Fig. 12.) Regenerator - ~ ~nerator diMnsions and porosity haw been ctptimzed with regtr"d to the combined effect of Qcle efficiency paraloget.ers and the cold start penal~ for both the INltrix and its botIsing. The flow distrfbut10n gep above the regenerator has been caref&l11y tuned to the dale-shaped top of the hOUSirl9. Thfs shape has contributed MUCh to reduced stresses and thereby .. l1er .. 11 thickness and lower weight, which results in less 'teat cOl'duction and cold surt penalty. The n!«luced diaMeter also lUcie it possible to Simplify the tie-bolted flanges for the whole heate~ head: tNo split flanges per quadrant without retainer rings: 8 instead of 24 pieces. GtIS Cooler - The part pt:».'fJr optimization takes into account the number of cooler tubes, which has been reduced by almst 251. Weight and cost decreases correspondingly. ENGINE DESIGN DESCRIPTION - COlD ENGINE SYSTEM Static Parts - For experimental purposes, the Mod I structural cold engine ~stelll was made up frOll! several lUting parts separated by Rl.ll'lerous hi gtI press;Jre stati c seal s. This gives COMponent testing flexibility but also requires ma~ extra machining tolerances and rigid quality controls since the functions of piston rings and lUin rod seals are so sensitive to misalignment and dome gap variations. (Refer to Fig. 13.) l'he Mod I-A design integrates a nllr.lber of the:;e mati ng parts. TIli s reduces wei ght and manufacturi ng costs and simpl i fies the asseBbly. Engine reliability also becOllleS i!llJW'nwd via relaxed tolerance stack up and reduced number of seals. For eXaMpl~, the cylinder-l iner/duct-plate integratio'1 eliMinates 8 large diamreter o-rings al\d the seal··i'lousing/plUlitbing integration eliminates 12 sma"'er o-rings. These integrated parts are made in nodular cast iron and aluminbm re spec ti ve 1y. the smaller cooler diameter results in redoced loading on the duct plate. Its wall thickness and support ribs have therefore been decl'I.'aS€'d to give lu!JI'er weight. With the new preheater bottoa plate. the cast-on flange of the water jacket can be elillJinated. Reciprocating Parts and Their Seals - Ttle piston rings have to efficiently separate the expansion side and the compression side cyclic pressures frOO! each other. 0" fference!> in seal capacity win result in deviatiPg cycle pressures unless a ~1l defined "reference pressure'" equal for the four cycles. is Clai ~Itai ned beUleen the r' ngs. Mod 1 has thl s $p4Ceconnected to the Cf.lllA1Ofl mini_ pressure linE!. (Refer to Fig. 14.) By arranging this venting througl:t the Qlinder liner, the whoie done vol~ can be closed off from participating in rapid pow .. changes. Cap-seal r"4!.fIl(Iv&l also requires the stille arrangellent. 11'1 order not to pas.s ove .. the venting COMe<:tiOft. the piston rings ast be aore than one stroke apill"t. This IIINftS thltIt the 1&fIPEf' ring is hOW , Ret cost t.O r TUftS Ret cost 1 ,...... ~-7OR 0.8 I 011 ! CI 06 06 0_ CI 0._ 0.2 'l -, n 02 0 i I , . D : ) ..o-.L.. I I 0.... :.a 11 J,eo.c-~Ylo.r><:'''-)O '~n _. ...... -... """'" Fe Cr ,., Co bat 16 18 75 bitI. 13 J6 S5 2.5 Fig. 9 ':;:;~ "I ' .:~ l i "~''S,,$ ; i ... ~·SlS ____ . ___ '" L ~ 1'-____ _ Fig. 10· n Fi g. 11 T~------- Fi g. 12 78 - HUlEn TUBES 1 FINS _CYliNDER _,EATER HUD REGENERATOR) HOUSlNG _~I:GENE· . "ATOll __ GASCOOl.EA -~ --.... -- Fig. 13 Fig. 14 --~---.----- sliding closer to the hot side of the engine. On the other hand. the dOile to piston attachoent area is redes1 gned to reduce heat flow to the ring: groove. It also still reverses below t:he highest coolirlg vater 1 eve 1. The pi st:on i seven desi grted to accept an alternative pressure-balanced t¥pe of piston ring. which is nlOW being rig test.ed. The sliding piston rod lUin seal ~stem is basically the same as for the present Mod I. The seal cartridge parts are only slightly llIOdified to givE! favourable operating conditions. nUl genteral principle is to guarantee good clligmnent and linear mov£t!lent back and forth. The rod centers all mating surfaces. The I'Od in turn 1 s centered by the crosshead and the piston guiding ring. Therefore the CI'OSS head 9ui des are mounted into the seal housing plate before final machining. givil1g a more accurate concentricit;y to the diameter that is piloting the cylinder liner. The sea'i cavit;y dimensions can allow altered PL-seal geometries to be tested. The Mod I-A pistons and domes are s i gniff cantly l'i ghter than thei I' predecessors and 1 end themsel ves better to lOlll cost production. TIlle weight reduction also results in sm&ller crankshaft balance weights. ENGINE DESIGN DESCRIPTION - ENGINE DRIVE SYSTtlM The Mod I engine drive sYstem is a dual crankshaft deSign chosen for stl"uctural synmetry and ease of assembly in the heater head area. Two, of the four cylinders in a square formation are connected to each crankshaft. Synchronizing the four working cycles with a 90 degree phase-angle apart can be made .in different ways. (Refer to Fig. 15.) Mod I has the two crankshafts coupled to an output shaft by gears but also has built-in possibilities to use a chain or links for the synchronization. Maintaining these options means a weight penalty. (Refer to Fig. 16.) H(}d I-A retains the gears. emitting the alternative synchronizations makes it possible to reduce not only weight but aho cral'lkshaft bearing dimens'ions and mechanical friction losses. One motodng unit with reduce:! bear; ngs has bl~en tested wi thout a~ functi OI'Id 1 proble.r&s. It '~as also tested with ill reduced capacity oil Pl\!mp and alternative synthetic 100»'1 caU og oil. Al though the eXpe4;ted pel"fomance glrin reaains to be validated. the mentioned modifications will be introduced on Nod I-A. In parallel. a more advanced design. ysing . rolling eleAent bearings instead of plain bearings will be evaluated throl.lgtl functional rig testing. It has lower projected frictional losses and a better low-speedJh1gh-pressure capabnu,Y. After successful tesU.,. this drive will be~ .. stronger candidate for the IIDd I-A engine dr'1va qstell. ENGI~ IlJESIEiId DESCRIPTION - COlITROl.S AIm AImIUWES Power Comrol - The Mod I power control ~steJ& has been built into IIOdular blocks according to the scheme. Major parts of thh ~stea are the I\Ydrogen storage tank. ~drogen cOlftPressor. !iupply. duap and short circufting spool valve .IM servo actuator. (Refer to Fig. 17.) To increase power. the spool valve is IIOved UJlll#4rd by tINt! actuator. Thereby. Iwdrogen flows from ti~ high pressu~ storage tank via tile spool va'ive through the supply line to the engine. To decrease power. the spool valve is reversed. During the initial part of the flIOvetlient. dtmping of I\Ydrogen frail the engine vi a the cOflIp!t'essor to the storage tAM decreases the power output. DuM ng tile second part. short circuiting of I\Ydrogen between the cycles is added. thus giving a quick decrease of power. Mod I-A Modifications - For MOd I-A. tt~ power COfltr~l system. in a variet;y of ways. has become 1 ess coop 1 i cated and heavy. The genera 1 re-arral1gelllent i s shown scheNti ca 11y i n Fig. 18. It has less plmb1ng and a reduced nmlbe!" of fittings and high pressure seats. This is partly due to the introduction of an integrated seal housing design. The new arrangement also improves the serviceability of the enti re engi ne systeG. (Refer to Fig. 18.) Air/Fuel Control - Mod I uses the Bosch K-jetronic Rlechanfcal fue.l injection system as the air-fl.le~ control device. Disadvantages with this system are: high pressure drop. especially at low air flows. difficulties in changing too air-fuel ratio and difficulties with altitude and pressure corrections. An alternative is a systel'll with a separate air fl ow transducer wi th teP';-rature a~ pressure corrections. and a fuel -e ten fig JIllIIIP wi th an equalizer valve as tim fuel distributor. Such a SiYstem gives a lower air pressure drop with lo~r blo-wer power consumption as a result. and a s1&ljlle Wl,y of changing the air-fuel ratio. (Refer to Fig. 19.) Mod I-A Modifications - Mod I-A will d~wtl"&te better autollothe Wpt1lbil1t;y. A ~ air/fuel ~stetrl and cOllbustion coatrol has been de\W.!'loped for tI\e Mod I-A. The s.ysWI sbown scltaitically in F~g. ZO ..ti11BS • pnoted a1l" blast fuel MUle -.1 will be -.~- Fig. 15 Fig. 16 81 ! i 1. SUi"fllY~ MiC SH00:T ~ 0I!WlT _ Y,""W :tEUCrno-... iIII£UUC Sl£1I'IO AC1IIAlO" 3. Oil. PUlSt ... oa. TAM: $. COtiiStMIT fi'AE:SSUM VAlYl .. 00. Rl."'" 1.It'i'~m~ .. MYHOEaa Alta "'_ ... -"' __ VIE n. _ _ CIlIIaliYIOiIIo_""'W "'~"COOLEA u. __l&S perfonMJd with exhaust 1.8S recircu.lation (EGR) at United Stirling of Sweden (USAB) and Keclumiul Technology Incoqoorated (Hl'I). Both constant lmll variable EGR vere ev&luated for their impact on gaseous _iss ions • EGR was found to have an expo- nential effect 011. ~. but none on CO and. He if 1. > 1.2. The testing, in addition to demonstrating good engine-to-ellgine repeatability. showed that AutClW>t:ive Stirling Engine (ASE) DeVelop!Mllll:j ProgrlJllilll requireillEmts for NO • CO and He can bib _t with EGlt. x -ONE OF '"1m REQUUlEHOO'S of the Department of Ener- gy-sponsored ASE Program (NASA Co;n1:r8ct DEl'U-32) is to d~nstrat~1 vehicle emissions Qverthe vxb&n CVS cycle ttUilt c01r.ply wit" the following: E- t ~'-!~.:~:~~~:::=~I21M-e§-=--~" _. ~ M 2.12 CO 3..4 mu He 8.41 2.:18 -_._- -----'--------- iGR. define,d as the dry volume of recheu- l8ted products divided by the dry v01..- of inCOOl- iIl3 air. WtilS s~~lected as the prUDe _thad of _issiona cOlltr>o>l for the Kod I ~ine (a first~generlll:;ion tmtOl1iOtive Stirling ensine). EGR is directed sp-oc.ificdly lOt; IID x ' wh.ere too increased h~lAt cl!p4lcity of the c~tiOil prod1.le~.s 10\l.l'tlll"S fl_ tell14p$raU\R and. b._ce. MO x ' Eillt is also ~ted to l:eciu'!r. In fact. 96'1. of the urban CVS cycle occurs within the region t;ested. At each test point. EGR metering area was adjusted to maintain constant EGR as engine power (fuel flow) varied. Emissions were measured at O. 10. 20. 30. 40, 50. a.nd 601'. EGIL Based on thf:se results, a tentative EGR requir,amGllt for the valb.icle was deteI1llined. and desis,n ,)f an EGR control system was initiated. Since it is Ill'Uch easier to design IUl on/off, as opposed to a aodulated. ~ control systea, the ensuing tests at Iff! eVillUllted the effect of constant-al'ea restriction Ol" the EGR line with a sil!Ople on/off solenoid cOill1;rol (siuilar to the m!lltbcd used on the earlier P-40 engine). With III c<:mst8llt-area EGR restrictiO!l. the amount of EGR varies with fuel floo becsmse of the air blower mad throttle characteristi.es. As a result, EGR increlUes e.s 11'1'%>1'1):[' decrea!ies. Both USA», and MTI use-d eeasureroents of O2 or COZin the exhaust (t) .mel oaobustor inlet (1) to detfll!1llino E;GR: l00(x.:oJ1. lEGR .. (~JE - (~JI 100 [0.2095 - (XOJI] ("Z}l - (X;~- (l) where. xt&.t ad Xo:l represen: the aole fr~ti_ of CO2 ~ma ~. respeetively. Ieeause bo~h COZ. ad O2 He .... urfld dry. t:he UGH calculated does DOt fndllMh water vapor ill the air or .u-t products. AI! USAI calculations were buecI on 02' whil. ~e of !ITI were derived trOll CO2, or the ..,erqe 0,£ CO2 and "2 . Sianarl,. l. was detemined fr_ exhaust Oz anct CO2, and a fuel hycho&en/carbon ratio (It): It 1 +"4100 ). • 2 4.17 leo (1 + t) 2 (2) The ensine test cell facilities and 110_- ission.. . measurements are described in detail in (2) and (3). and the _issions equipMDt is defined in Table 1. Table 1. EDissions Eq .. ip1lle1lt -~!Io - ... ~- 02 - _1M -...... co. - -- ... 11.., ........... 1;0 -- -- .. - ....... ItO,. -- -- - . , IC -- -- -- GASEOUS EMISSIm.'S TEST RESULTS USIUl ~ _is5iol1s at constant ':EGR are illustrated in Figure 3. The value of l. varied ootW0en 1.5 at idle to 1.2 at higher fuel flows (Figure 4). The influence of EGa on ~ is clearly indicated. As EGR increases, the proportion of CO2 and H20 (e.g., the nonaal products of couplete cO!ltbustion) in the cOllllbustion aone increases. raising the heat capacity and lOtlerhlg tile fl_ tE!tlllperllture iii proportionate liIIZIOunt. Due to the elI:llOtlential effect of flut: telillp1lrature on ~'Ox. NI!'Ix i~1 reduced. In fact. since fl_ telDperature varies proportionately with EGR. NOx is an expo- e.entiel function of EGa. i.e •• as &Gil increases. its effectiVEtness in reducin& NO dbtinjsh~s. NOll eIIIIiuions in Fi&ure lX are presented as e!IlIisaiems. index (El NOx) defined as the ar- of NOx P"ilr ltilo&r_ of fuel. Eaissions index is dir.etllJ related to ASE Proar- emissions goals eJqlres~.ed iil &lfiIli &n4 the urban CVS cycle aile8\ge' (mpg): lU .. 1a/tdH!pv(lOOO ~ (3) IIf where p .. dem;itj' , of mlaaded gasoline .. 2841 &1&&1. lfhus. to achieve 0.4 alai. 60-701 EGa is requir~lId. while -m EGIl would suffice if 1.0 11m is required. ·,.- 12 8 • o .----!-a ~~..-"lI- o 1.0 g/m (19.3 ~ I.IfbNI CVSI -------,------------ ~-----30 6 • a a Fig. 3 Mod 1 Engine #2 NO x Emissions with % EGR HI 1-'1 1.~ • u- 1.2- 1-1. 1-0 o ~~IJ[t ... "~---o o --0 3.40'''' 1111-3 III",: \Iillall CVSI ------------------------- Fig. 4 }(od 1 EngiM '2 II and CO f.l:aissions 81 co aIlIl JlIe elliastou au froa USAB vere both ext~ly 1011. co ..usioas CPi&UAt 4) ..... 11 b .. 1011f the AIm hosra reqa1naeac of 3.4 ./'u. There .. y be .. poaitJ .. 1aflUDCe of EGa: OIl CO. but: the effeet. if any. is .UPt. IIC _lrnioDs (DOt shown) were less thaD 0.1 8Ik& 01' an cmhr of lIIapitude lover tJum required. m te!>1tiag in wo Ifod I elJ3iaes utilbed a constallt-area: reatrictiOll in the EGJ( linlll. es previously dflscrihe4. Three EGa schedul_ vere used: "ao ElGR." "iDteruediate EGa" IISUl "aaxilma EGR. n In dlilt first case. the solenoid control valve was shat. preventing 8lty recircalation. KaxiJItwD EGit vas obtained by reIIOvina- all restrictions from the line; interaediate EGR v& obtained by edjustin& It band valve to ~taw an MOlt level of -1.0 &lmi. The intenilediate- 8ltd lIIIIXim_case EGa char- acteristics are illustrated in Figure S. The non-EGit C8SID (not shocm> is ~. As power is reduced (lower fuel flow). air flow is restricted. increasing the AP across the EG1t circuit (see Figure 2). t ad causing EGR to increase. Also ROOll in Figure 5 are the three \ schedules (li). \Y. 8ltd lC)) that were used during testina. 't{;e USA) sch~le ® (Figure 4) is very close to @. The effects of EGIil and \ on NO,,; are given in Figure 6. As WIllS tbe case with USA! data. the influence of EGR on Nf\: from engines No. 3 and 1 is pronounced and exponential in nature (Figure 7). The repeatability of NOx is good. especially at interRledi!ltj~-EGR levels and the ch8ltge in }. does not appear to affect NOx ' The maximum EGR sched- ule would suffice to Het a 0.4-g/8i NOx I :> a #: I a: 0 w 10· en "0 :l0 10 o ). B A 0 C 0 A <> B 6 Iftl C ') Max. & o as. Fig. 5 Mod I Engine Variation in ). and EGR with Fuel Flow - -'-".";,.'.""""~" -. '1 -. rllqUlr11lf11i11Dt. Tile iIlt..~clJLat.. EGil schedule is seen t.o be very clOGe to 1. 0 alfIi.iIl fact., if the inteJ:lRdiat,e NO,. reaults are enill8ted for the CVS cyel. usill. If-tiIM wetabte4 f_l flows (4). PK'edicted C::VS eyc.le NO. would be 0.88 &/_i, c:orre- slmndin& t.cl a 0.4'1 decrease ill -"sille efficiencY relative to the oon-EGR case. 1 .. I' ~ t i III 1 ... !' CD 1 ~. OJ ,.- Zll 20· ••• le· ... '2 10· 2 o o fill Il'1O lat >. " .'0 : III .,. 0 .. , .. c CI IN- A ¢ ... • I> ~ C ~ fSil!!. 8 • r ~ j f .. T' ~ ~ Jo .,. 1 $ 'i 1---------2~'--------,~--~!-------~ Fig .. 6 Mod I Engine N'9 0 • '.0 0. .. 1.1-1.4 Q a 1 ....... 6 Q 1.0 6 Q.4 t~~~--;m·'b·-iu---mtJ rol\ ... llIOry~ Fig. 7 Effect. of EGR on Knd I Ena1ae NOx EmissiollS ... ~ I f "l ~ ~ ... l <£" -- A eoq>arisoD of the Nl\,; _isaions of aU three Itod I engines is PVeJl ill Ftau. 8. Ooce &pill, the aar-t is acocl, espedally with EGa. 11Hl tendency of ~ to peak at fuel flQllolS of 1.0 ala or less is not cOlipletely understood, but. appears. to be characteristic of the turbulator cOlllbustor. For eluI..,le, the Sl!!I8Il curve shape was seen during alternative fuels testiQa of the P-4O engine with EGa; see Figure 9 aDd (5). A possible explanation is that offsettins effects occur as fuel flow decreases: • tGR increases, leading t.o lower NO x • ~ increases, causing flame temperature. resi- dem:e tille. and hence, K~ to decrease (this statement is true if .ixing of fuel and air is perfect prior to COIIIbu5tion; e.g., ~ is uniforw in the reaction zone) • Efficiency of COIIIbustion mixing decreases becaIJ."Ie air flow is decreasing which, in turn. leads to lower cOlllbustor AP and turbulent 1IIixing. With large variations in ~ inside the combustor. the burning reaction is character- ized as a turbulent diffusion fl_e; e.g .• combustion ~curs at near-stoichiometric conditions where NO x formation is highest; thus, NO x increases. At very low fuel flows. the first and second effects dominate; as fuel flow increases. the third effect dominates. Further increases in fua I flow improve mixing so tbat NOx again decreases. 2S 0 am M11 0 • • 0 2. .. Q 10 .. 4 '2-.7 • • 0 .8-25 22 .•• • 0 ~ 111 Q a 3-33 " " 9 - 20 • () 47_ ... A - 0 • ! .. .. ... .!' a. ~ ~ 12 • iil --- .. • 2.0 0 0 is (S ~ 1-0 f "I ~ ~ .. • 0.4 i." 0 s -Fig. 8 Hod I ED&lne *>x EAissions Vith/Vithout. !CR .: co emissions results froa MTI testing of. Mod I engines 1110. 3 and 1 (Figure 10) indicate an effect of bc:.th EGR and 1 on emissions. At first glance, the effect of EGR on CO seems to contra- dict USAB test results (Figure 4). However, care- ful analysis, shows that this is not the case. In fact, CO emJlssions are very repeatable among the three engine:s. Comparing Figures 4 and 10, CO increases with fuel flow cllue to the concu.rrent increase (with fuel flow) in cCSlbustor air flow, thus reducing the amount of residence time in which CO oxidation can occur. For the lowest ~ (least excess air), schedule (!), increased EGR is beneficial .to CO, probably due to the increased presence of OR radi- cals promoti:ng the oxidation of CO (6): co + 2 OH + CO2 + H20. As l. bncomes leaner <@ ~ @ ... © ~ ®). the ill1p8ct of EGR on CO em:lss ions is s light. or nonexistent, leading to the conclusion that as 10Ilg as Wlough excess air is pr·:..~ent; e. g., l. > 1.2, [Gft does not influence CO. A study of Figure 10 indicates the importance of accurately cont~ ling L If ~ decreases below 1.2 (schedule @), the CVS requirement of 3.4 g/mi could be exceeded). The reJ>eatability of data and the extreme sensitivity of CO to l. are clearly indicated in Figure 11. It may be concluded that: :/2.Q aoo No EGft A El lao a 0 a 16.0 • X 1"-0 e I;) Go ~& ...... Fig. 9 NOx Emissions - P-40-7-15 - ~11 Fuels • Neither EGR DOr fuel flow are important ill cleter.ining CO _iuions • CVS .:ycle COlIIpliance can be. as sur" by l14in- tainiDO 1 > 1.2 • CO eadssions for all three engines are consist- ent. DC _issions (expressed as methane) obtained during KfI testing (Figure 12) are well below the CVS cycle requirement of 0.41 a/mi; in fact, most of the He emissions are an order of magnitude less than th'" requirement. USAB dat:s, as previously mentioned, were less than 0.1 g/kg; however, the He efIIissions do not reflect those that would be obtained during an engine start-up sequence. Vehicle experience indicates that HG generated due to igni1l:ion delay and cold start may be 90l or greater of the total _asured. CONCWSIONS EGR, in combination with the turbulator cOlllbustor, is a viable method of controlling Hod I Stirling; engine exhaust emissions. The effect of EGR on NOx was exponential, as expected (1). If steady-s.1:ate engine data are projected over the vehicle CVS urban cycle, an NO goal of 1. ° glmi could be. met with 25-30% EGR, w~ile a goal of 0.4 glmi would require 40-70't EGR. 1 ... '" ~ '" I 8 iii E,,!~ 0: ., EGA ). ., .'0 B a w'o A 0 ./0) C 0 Int A <> Int e A Int C 0 NIAIt.--!.. Fig. 10 Kod I "ugioo CO EIlissions Vith/Witbout EGR - -<--~------~ "-',-},; 100.0 - 50.0 ---_._---_. __ ..... • • 3.4 g/m (19.3 mpg l./ftIIlln CVS) ---------------- 20.0 10.0 - 5.0 2..1l1 - 1.0 O.S o 0.2 co .. I at I .. wJo 0 wlo 8 I w/o A JI~j L..._--1 __ "';;..J-__ 1---:- -----1 0.11.0 1.2 1.4 1.; 1.8 2.0 Fi~. 11 Effect of A on Mod I Engine CO Emissions Doth CO and He emissions were 10;0 as long as ). was greater than 1. 2; a s light posit ive effect of EGR on CO may exist. Projecting steady-state CO and HC emissions over the CVS cycle indicates leve Is 'i-'e 11 be low program requ i rements; however, it mus·t be emphasized that the steady-state projections do not account for start-up an~ tran- s:' ents encountered during the CVS cycle. S1-nce He and CO are adversel} llffccted by start-up and tranSil'lts, dctusl veh.i<.le measuremer.:s are antic- ipated to be higher than indicated in tais paper. ':....,. -. ,--_._----_._---_ .. _. __ •. _._. -- U· CUI fIIr" (11.3 ...... \JrIoeft c:vs. -------------- " .10. o o .10 A o .10 C o ..." 0.... A ... c: 0__. o Fig. 12 Mod I Engine HC Emissions With/Without EGR ?EFEREt,L:: : 1. -"~ ll. ,/. A., and Thomas, M. E., "Effects of <:1. Cc iitions and Water Injection on EOlis- sion.. from Dual-Fuel Industrial Gas Turbine," ASHE Paper 81-GT-47, March 1981. 2. Nightingale, N. P., "USSw Acceptance Te'it Report Mod I BSE SIN 2," !tTl Report No. 82ASE270ER40, July 1982. 3. Daly. J. W., "Combined Alternate Fuels and General Development Tesl Results of ASE P-40-7." MYI Report No. 82ASE264ER38, August .)82. 4. "Iighti~ale, N. P., "USSW Acceptance Test Report for Mod I SES No. 1," MTI Report No. 81ASE237ER32. September 1981. 5. Battista, R. A., "Stirling Engine Alternative Fuels Test Results," !iTl Report No. 82ASEPR21, CCM Paper, October 1982. 6. Battista, R. A. " and Farrell, R. A., "Develop- ment of an Industrial Gas Turbine Combustor Burning a Variety of Coal-Derived, Low-Btu Fuels and Distillate," ASHE Paper 79-GT-172, !'larch 1979. AUltomotive Stirling Engine I)evelopment Program Stirling Engine Alternative Fuels Test Results ABSTRACT ~ Emissions measurements were made on a 40-kW Robert A. Battista Mechanical Technology Inc. deterioration in the system over the course of the test program was monitored; other engine parame- ters were also measured during testing. Th;.,; paper concentrates on the results of the emissions ~easurements; EHS performance results are also discussed. Results of overall engine performance can be found in (l)* and further details of the emissions results in (2) and (3). (54-hp) Stirling engine burning five liquid fuels - unleaded gasoline. shale-derived marine diesel. gasohol (ET-3). ERBS. and commercial dies(;l. Emissions ~Iere measured with and without exhaust gas recirculation (ERG). and the results shO\o1ed Ii tt Ie difference in the levels of ~Ox' CO. and He emissions for all the fuels tested. particularly, TEST DESCRIPTIO:-I \0.' i th ;::3R. ------~ .2-~L .'~ ... ~i 1'Iri-&-~~;.." results of the test and correlations of the emissions data wi~ external heat system (EllS) parameters;-The effects of the fuel type on the performance of the EHS is also discussed. THE DEVELOP~ENT of a high-efficiency, low- emissions combustion system is a n:ajor requirement or the ongoing Automotive Stirling Engine (ASE) Development Program at ~Iechanical Technology Incorporated (~rrl). Among the major program goals are to demonstrate that the use of alternative fuels is not detrimental to engir.e operation, performance, emissions, or fuel economy, 3nd to determine the degree of minor modi f icat ions or necessary adjustments when s,.i tching fue Is, Th is paper covers the results of the first comprehen- Sl\re tests of combustion/emissions ... here a Stirling engine was run \o'i~h no h'l.rd"are changes. In December 1981, emissions measuremert" \o'ere made on a :'O-kW (3:'-hp) \:-4 Stirli:1g engine ,::'-':'0-7. Build :5) burning a variety of liquid f'leis. -:-h,e engine was configuced in such '1 Ioiay that me-lSll.rements could be made with or "ithout e:thaust gas recirculat ion (EGR). enabl ing noL only the determinaL ien of the di iferences in e.tiss ion leve Is of the var ious fuels, but a Iso the eva lu- ation of the effect of EGR on sax, CO, and HC :or each iue 1. For the External Heat System (EllS), consist- ing of the combustor, preheater. fuel nozzle. and ,air/fuel control. including inlet and exhaust sp'tems, pressure and tealperature measurements .ere taken to determine the cffect (if any) of the variOl's tue Is on overall EHS perforwance. .-\.ny TEST CO~TIITIOSS - The fiv~ fuels listed below were tested over a load range from idle to maximum pO"'er: 1. 2. Lnleaded Gasoli::e Shale-Oil-Derived ~arine-Diesel 3, Research-Grade Gasohol (ET-3) 4. Experimental Referee-Broadened-S;>ecificatic:J (ERBS) T~rbine Fuel 5, Commercial Diesel Table 1 summar izes the fue I propert ies, :l",j Table 2 desc.ribes :.he ~F!st matriX run ~n eac.:: fuel. After the last fuel I.'as tested, severa: ::)ad points tburning unleaded gasoline) wen repeated. Emissions measurements ",ere made \o'1t2 and IOithout EGR at each test point of the matrix. ,he EGR levels achiev(;d during e:lch tes~ series are shO\o.'n 1n Figure 1. For each fue: tesced, the variation of EGR with fuel flow IOas similar. The largest differences in EGR levels ':)ccurred at. :~el ~!0\.'5 less t.~an :2.~ g/s. ~e ~ igure a Iso lndicdtes that the EGR ,,"11 .... e closed at fuel O()(o{:. of 0.7 g/s and lower; ho,.-e .... er, this i" the normal method of operation for the \·al .... e. Overall EGR levels appear to be ~ome\olhat 10000er than those measured dur ing the 5.cceptance test of this P-40 engine. as "ell as for those measured during ~he P-~O-l acceptance test. This may have been due to differenc"s 'n pressure loss- eS across the EGR clrcuit during each test. Th" ""umbers it! parpntheses designate references at end of paper. - . Table 1. Fuel Pro~erties (Analysis IIVlCIe III PIIOenIx 'Chamlc:lII labonItofy. Inc.. Chicago. minois. May 1982) ... o.Mld ColD- , ........ ....... GII80bDI ~ G!IIIaIIIne' ....... If,T-3)1 ER8S' CalI/M'IA wt% r 116.00 86.52 82.30 86.94 1fPr~ wt~ 13.84 1328 14.05 12.73 f&!I8ur wt~ 0.02 «20 ppm) 0.02 0.045 ~ wt% 0.003 0.002 0.003 0.011 Oxysen wt~1 0.13 0.10 3.63 0.17 LNIII ppm 22.9 <0.1 9.9 <0.1 Spodk c;,..., 0.752 0.834 (1.767 0838 APt GnmiIy 56.7 382 530 37.4 ~@40'C C.s. 0.55 2.54 0.59 1.62 r;aM Btullbm 19.610 19.720 18.844 19.525 18.347 19.508 17.562 18.363 'Averal/8 01 two samples tal18 can almost _ply Table 2. En~ine Test Point ~Iatrix Pmean IEnglntl 3pe<1!td (rpm) DI80sr 86.85 12.78 0.095 0.008 0.16 <0.1 0.843 36.4 210 19.507 18.340 I r (MPa) Idle 1000 --' . 2000 3000 4000 15 - 4 3 2 1 10 - 5 6 7 8 7 _. 12 11 10 9 5 - 16· 15 14 13 Idle 17 - - - - - --- _______ L-__ ----;;;;;; ·Because of test difficulties. test point 16 was not run i ~ " ,l ~ .. ,. 50, "'.It- !Klr- 5O~ 15:5 " Q o..e", \ _,"_.7 _. ______ ._ a: \ ~"'tit • • 't -, .1 :0 • -~~., • ll...-----.-'-----~---, l ':1 l.O 10 oJ --.~. Fig. 1 EGR Vari.litlon :luring "lt~t'nativ.~ Fu .. l r~st" blower speed was also lower than usual because of variator belt slippage. It should be noted that the EGR values reported for this alternative fuels test are volumetric ratios of dry exhaust products to dry air, as determined from measurements of CO? in the combustor inlet and exhaust. The COi measurement was also used to calculate and set A values. At the start of each day's testing. or when a new fuel was tested, the A value at cruise (2700 rpm, Pmax : 120 bar) was checked and set at -1.25. The variation of 4 with fuel flow for all fuels is shown in Figure 2. E:llSSro:-;S $ASl:RE!'1£!1iTS - Details of the Gas ~alyzer System used to measure CO, CO 2, SOx' and lie may be found in (2) and (3). Smoke sl\lllples, using a Von Brand Smoke System, were also taken during testing by passing a sample through a moving f i1 tel' paper l-100 mm/min); the smoke number (100 indicates a totally clear exhaust) can then be deterulined by measuring the reflectance of the sample relat:ve to the clean paper. In order to eliminate interference of \Oater vapor on SOx measurement. moisture in the sample \Oas removed by ora.lng it through a re::rlgeration bath ?rior cO it entering :he SO detector. It is important to note that the .ater k.!10ckdown is done after the ,"0, + :\0 sonv.~rter. since SO 1S :nuch less soluable :han :\0c' ninimizing the amount of SOx lost during '11 0 remo\·al. CO, scrubbers were used in the CO s3mple :ine to pr;;\'ent :::terference of CO, w:th CO detectlon. All of the las ana:yzers , .. ere cal ibrated prior to each day's test1ng, and several call- bration checks were made during testing and at the end of each day. Th.., raw " .. iss ions data were then corrected for lny instrumentat ion drift. OTHER I\STR~~E~lAT:O\ :ncatlons of ,-HS temperature ,1Ild pr"ssu:e measureme:1ts are shown schematlcally :n F!~ure 3 .t each r·3dial pOSHlon -< , ~I- ~ ~ ~ ;) . sf- .... ~~ .... AItoMtt ( ~\)d =~~ ? 9lf!S ;);)- '~---~'------~l-J----------'~J-----------OJ ~"'~-9" ..... :_uabda Variati.:on ~rin!t "ltet·n.itt"" fuel r",S! (All ~'uels) I tIC-AI T/C-HS T'C· .... TIC-£)( T'C-HT P_,.., __ ee PI :: CombustOJ Inlet 4PeXH "Combustor toIet - e ... haust 6PCOUB := CombuSlottnlet - HeawHe:adEltlt Instrumentation Schematic shown, at least four thermocouples .. 'ere located circumferentially around the EHS. '1ost of the thermocouples indicated are standard "ngine test instrumentation; additional thermocouples ... ere used to determine combustor inlet.,exhaust temper- ature distributions and, along ... ith the pressure measurements, to det.ect any deterioration or abno~malities in performance, There ... as concern that operat.ion "'lth heavy fuels could cause plug- ;:;ng of the preheater. :-EST ;\ESL'LTS A complete sUlnmary of :he fa'" emiss Ions dat.a (corrected for inst. rumentat Ion dr i ft) recorded for all Uve fuels, and inc ludlng average tempera:.ure data throughout th.! EHS may be found in 3). ?res- sure dat.a are d iscus.sed ~n the next sect 10n. :be SOx Emissions lndex for ~acl1 :u~l :s compared In Figure~. :lata -lr<> silOIOn both I.dth ~!ld "'lthout EGR, As noted pre\':ous:y. EGR ?"rcent.age .. as aetermined by r:'1E'aSUrlng CJ~ :..:1 ~.he t~xhaust lnd :n;('t to the .)~,bustor ';:>r"hedter llsehar,;;,,:. thus. \: ) 'feR Iolhere: Xco - Mole F'raction ()f CO~ \~teasured Dn). 2 ;he .:tat a , plotted as s :unct.lon of fuel ::010:. "en, corrected fnr ul),et !'nalldlty :·<'11,''''l.1l~ the &as turbIne practlces \~,).Ol of correct~n& to an absolute h~ldity of JOb) g H,J,g dry ~lr. Th,s corresponds to " l5°C day .nil 00 .... ~eL!tlve hlllllld- ity. "corre14tloll of the :Onl ~ II 1so • SCI l( "(H-.006) _as x e ~~1iIM lI ' a-I;j' .... It. '- 22.0 !2'.!.!!!!!1!~ ai_a--, 01_011 , x: !T3 20.0 .: EJIIfIS O'OooMl .... £GIl • ~ '1.0 :) ~ <) 0 '.0 '00 :) ~ .. .z..o i :1 :) ;; :) I 'J ~ ! I ! ,J I- ,L .... , 'J 21 lJ " =AII=~-a·' Fig. ~ SO x Emissions P-40-7-15 (All F'.c Is) \OdS '~sed •• herE, H '" measured absolute h'~iditv .... value of k = ~3 (previously used by .M auth~r to -orrect gas turblne "'misslons) was chosen, ;n \'~e. of the :ack af s:ml:ar re:at:onshlps for the S::r;lng englne, the 3ppllcat:on of gas turb,ne ?~~ct:ces seemed Justlf:ed. since both are con::n- ;,QUS combustIon SYS"'PfBS. -3.nd the excess air fac:~r :n :he pr:mary zone oi gas turblne combustors :s ':ery close to that ·"f 1 Stlrling englne ::omoU5t:::r :'he ,:orrect:on :educed the scatter ... 'm;"aded gasoline -lata ::etween ::'e :n:: la! ;nd :l:ldl ~ests ,3). :-~fI' efffl'Ct. of hunudlty ·.dS -:'!C:-e ?ro!)ounced .1 t.hout ;:GR; \Ii 1 :n EGR. the dmb !~nt C\o:sture l::I'ct · ... as ",,.rs,,-acOIOed by H....) ~nd ot~ .. r il:~:P:lts :~ :he ~ec:rc~:a:@a ~xhaust_- -:be l~pcrt.lnt res:..!:: :.S :hat \~ 1~\·e:s ::)r )1: f:ve ::le!s .)rp s!m!:ar~ ?llr!:._ularlY.1.01!h E~R. :hus, ~,:lllitle ~':.ombustcr ~.an be deslgned~ USll'g i .lxpd :'l.JR (')r ~....,R r,:o.mbas!.:on gas :-ec:rc"..ll.it:;:)n' ... ..:·:-:~(:~:e. :!1dt .::: ..... i':.:st'y :::'e ":-\'S _yc:e ~m:!Jo" ~lrop·ert:es :>1 the fuels tested do not rl::er gredt:v ,705ble ::, :,ut :h., results ""oneth,,!.,,,s :"~pre50ent. l 5!g,nl!:'Cd.nt. 'Il:es.t.one.* :n gener~l, :he steady-statt'! SO :,,\'els): the ?-.. O Stnl:ng .. ng1ne "t :he ,e~e:s ()t ::::;i\ ich'""ed .. .,re dl::oV .. :he CYS : l!Alt of ... ~"Dl .. nen based on a :Ello'age t !g.ure ::)f ~~ .... ltp& : :o!"respond- lng to ,ul EI c)f 3.~ S/k.g). e$poc.lal~y ~ear :dle .. here t:'e EGR :evel drops "if 7he ell: !.~,,; "rueh wah lH&Der :l1t:ogen content or :ilUerent :!,,- :&lJlperuures ,.ay requIre s!tered :,",°.15 of EGR,cr;R for so.. coeplance, • A system is rather' cyclic at low fuel flOlo's, as indicated in thE: idle emissions traces of Figure 5. The air/fuel variation is reflected in the oscil;ation in the CO~ level. ~nder these condi- tions. actual CV3 cycle emissions Ioill differ significantly from calculated emissions, based On values taken from Figure 4, ""hich represents \'(} 1 ues m idw-ay bt:~t\r,,'een max imum -1nd minimum tH~aks, not lime-.lverage values. i - : Dlfecnon of Chart -.:- - i , , Unleaded Gasoline i , Fuel Flow = 0591 sec i I No EGR ""n i '1 ::: -3E"""""! 1 1 ~,,!ZlH~lill §!:¥:$¥il$- : .s: ! . -- , ~ -~ == ~::::st:i-= co ;:;;.= ... :. ""0 .. __ ... = ' 5 i .1.. ..- I I -::;: ;;:::;;;~ : . "'''' Sif!~ _ ',' ...... ( ...... I! ~ \ . "',', I : :~' .• ' ...... , . . ,' '" .... ~ , .. , :·.,t 1 ~. : I : :.~ ., " .. ::: ~ i:-P \:'~~':"'::':':i:'':\ : ..•• '1;t-' I'" :~' ..... I: ,,,;::- ·' .. t', ~~;"" ... , ' ... : :~ •• : •• : :\.' 1;';"~1r- :...;.~:~.:- : ·.t' ::~.~ : ~:. .·~:~:!~e 11:1: .':-~", .. , ... : J:' .. 1 ... ;>.j:- i 1! ... ": t" r .... : ~~ d : "iU r P ...;. t··:.·:' 1 : . :~. .... :or .... : : .... ~ ::l:.' t : :. 1. ~ ::-: \. 1'" • ~ '"'! .. :: ....... _ :. , .; _: t -. - : ... 1~ .1 06 05 - i.: ,'rr ;"·,i~ ... ·ht·rt.· : - c:J I Un_ Gasoltne i e Shate Ott X. ET3 ,. ERBS .q ;C.~.l:-,urt.·,: !.:~:.·t :t.·;,t't.·!":: .r •. : .... :., ~ (:.: 1 : \',. • ,,'t',: ... :: . , .~ ... : i '': t :.. .. ... .. ~ , . - .. ,' '~ . ... ,. ~ , .. ~r: :: t' :.-~: P. .,: - '.: .. " "::,d : ··n(~r:,· <.l:.:: . t' .. ,T. ... 1: : " ~: : ~;.- , . -\., : ".> - • _. I.:.',: ··'\.:.1 .... • • : . : ~ .' !' ' •• _ I:, ... t' ! : : : t~ r":l\.. ~" .... t:':..:! 'l~""" ~',~ ",-tt ·.··t~·"::,'~l. ! -: ,~ .. ::: (h : -'.: : .4- ' .. .. ,:: : ... .., : ::~ ~ ""\ .. ' : .... ~... y, :1':..1 '.to:·.- .1:.:~: :; ... ~::i :..; it. : :: t" ... ~ ~.. : :.,' '. •• : ';.; .! t .... ;.1 _ ... ..; ••. ,. :,."., ~ .',: .. ,. : .. ...;. .. :- ..... -_ .. • can be used in preliminary combustor evaluation. Emissions Index was adjusted to an arbitrary reference inlet temperature of 800 GC using Eq. (3) and plotted as a function of L Although the correlation cannot totally describe the NO x data, it does afford a somelOhat better representation than the uncorrected data (Figures aud 8). Figure 9 compares the non-EGR ~O levels as a function of>. for all the fuels :estid. 00 ...: , 0> l o· Z .:u ::> .. ::II -, " "T 22.0 20.0 180 16.0 '''0 f"~ o . Di!ta Corrected to 15' C AmbIent. 60% RelatIve Humt(jlly '20 ------.--~-- 10 , 5 20 "1.:. ~~~-~·\.~l't If ,'!1 ;~()x E::1i~~i~lns l'l)rr,,·\·~<..',; ~, .• l()f):l(' !~~!t·t ·)- .. d-~-11 - ';,' ~-!:t\ 240i 220 t- ~o~ I '50 ~-! '60 ~ I I .+ I '2 Q .. , ) . 5 '1.:. .' .'r!",·..:t\.·~ ~'"-'.x -""_ - -'; - '~ .. ) t::.l~R 91 1M! The increase in Emissions Index with increas- ing X is consistent .. ith the fact :hat residence time also incrf'ases while fuel flow decreases; thus. even though the flame t~mperature is decreasing, Emissions Index can incr~ase. An expl,mation for the inflection point (most distin- gUishable for the diesel fuel data) has not yet been found. although the classical :\~ versus A ::"r\"e pCdks at a sii,;n:ly :cdn conrli:lon ro > 1.0). The value at \, at maximum:\O depends. among other things. on residence time. x CO and HC emisslons for each :'l1e1 lre shOloin in Figures :0 and 11. Again. trle "mh",ons .. ere similar for ,:1 fuels ~~sted. The slight di!!"r- ence in CO emissions among fuels ,1ppears to be ,]ue to the deviation in ~t 35 ind~cated itl F:~ure~ :2 Jnd 13. and not fuel proper~ i(>5 .1S on" "'l;;ht expect. The g,dscline ~at..l .:OfT':>drp. ~.)·, .. crlt~y ... ::h ?reviaus en&in~! diltd ::.31. 30th ~~'I lnd. ::c 1:·.~ :,elolO the C\'S !imit~:of 2~ ~ " ~4 :'" .. : . 3.- ..; ml !t ~2." "'pg.l ·md C; ",k;;; .-l ~.,., it ~_ - Clp,::. rf .. o.;,p{~ct ively. !t:~ :;-.t.-,,:-·lI-';: :~':~ :~~ :~!:-:p :~ll:' :~e '':0 ~m15sions .-:t:t ::GR ',.prfll :~),""t'r :"::i:1 ·~::,: .... t· ' ... ::~ out ~~GR. t~xcep~ ·It \'pry :,)t.." :'4'': ~.:_;!".~. :--~i:':; :'-ly be du(> :~ "'~\'erd! :'~:1~cr:s' :. h ... tdd::: .. :: 1: :: l~o; :·~o",,· :.lay pr;:)d'..;.ce b~:.t. ..... r ~:X::l~. : .. ~~::::.~ .:1 -:-: .. ;!"f-' ·.ampl('tf~ .. c:::nou~t :'Jn~ _, 1 .... : :-'~!:.;.~; ',! .••. : ...• 1 :::. .:-:)- :9: .- :~; .- :.,: -- ~ :2' - .:-:; - - ~; - .,,.:- '.a.)_ .. ",.-- .... ::." . '.': -.; ........ / ( S"9S f / " rJ I .. .... ::-.:: . ...: :: .. ' ~J- ~; - .1.:- ~!. - .~: - s;- .;; - '': - ! / r /"' /' I .. - ..-------------- "-l..! - -. :. i it.' l t .:, .. 1'( :,,: <'t ~"n '~4.\; .. :- !' ..... : r~· .. :-e~V"'r- I! ~.rt - .. 11- - - :, - \,' ; ;.t _--·'6 1~.0 12.0 ~ 100 ? p 80 0 u ;;j 60 00 20 J ; '60 r- <0 r: '20 -;: "~ :;. l ,0 - -30 i_ I ':'-J~ ~ '.I ~-- '':: - '.) .=: '-- 'f i ~ ... '" - :; '3': .- .\ 0'· ZO I. , J l J.I • uSS .. ReI 81-00051 "<0 EGR ~-6'" , 0 ... , , ... e F ... .,IO - EGR ~ \ . ~ :J 20 Z J o o • 30 40 30 ----------------, ,--=.::-::.._---... :O:~~~~ .~~,,"-,, l~iS-OQ« '01 !'T.)~' fI>' ;:Pes 7 1 J~ ! .---------------~ --, a . z . ~ ------------~~--~·~~~---~2 Flg. 12 CO Emissions v~rsus (P-... O-:-l ;) ..- ~ ? p - ,;:j • NoeGA ~~ • eGA • I I ,. • .. -,' • i i O "" ., !---!. • • io· •• i i " ~.E!! • .. .).2 ,., J2~ ~~ ).1 • )} ..... 11. Hw . t. a • .lw ;2 r ~~ ~ . • II J'r • ) ~'~~-'-J--'--------z·.O-----------l.-,----------,) '2.0 ~ ; ! 6.0 ~ i I ~o I- \ I 2.0 ~ :'.Je'I :10. ;,' :i". 11 He Emissi,ms P-:'!)-?-I:; 01 .JnteeOQd ~ ( . ..- .-..-.... "'-"'0 .:I.I_·J" C::r·l~1 .' :1'8S 7 1 ::::...s. All "- - No EGA JL~~~----i l8 • J • 2 • .. . ;; , 3 2) U Filt. 13 CO Emissions versus' (P-':'O-7-15) - --------. ............................ I ................................ .w~'~~~~ .. ................................................................. .. race; and 3) for values of A near 1.0, the longer residence time associated with the non-EGR condi- tion (lower mass flows than comparable operating points with EGR) as well as the higher temper- atures, may inherent ly result in high CO concentrations as CO approaches equilibrium values. At low fuel flows and large values of A, the quenching effect of the exhaust gas predomi- nates and CO with EGR becomes greater than that without. Although very similar, Figures l2 and 13 llso support this trend. Steady-state HC emissions were extremely low for all the fuels tested. Ambient He levels in the test cell ""ere, in fact, an order of magnitude higher than the exhaust emissions. One might expect HC emiss '.ons to be low, considering the high react iOll ~ emperatures and large numbers of hot su~faces where reactions occur. It is impor- tanc to emphasize that these are steady-state data. As Figt;re 5 clearly illustrates, the emis- sions levels can vary conSiderably during cyclic or unsteady conditions. During transients, considerable variation in emissions levels can be expected, and steady-state relationsh~ps between emissions and combustion parameters are not neces- sarily \·alid. This is especially true during start-up. Thus, Integration of steady-state results over the CVS cycle (to determine compli- 3nce) is, at best, a crude approximation, part:Luldr:y if d I~ombustor is kno1,..·n:o perfo!·m poorly during t~an~ients. Even in the cases where transient tImes are long relative to combustion redCtlon tU""5, and the combustor is stable dnd wpll designed, it is difficult to account for the effects of thermal time lags on the rest of the EHS; hOl.eyer, in this case, the ;>redictive accura- cy is cer:dinly improved. The "",oKe data have not formally been ff'duced; hoo.;e\·er, the filter paper was clean at 0111 steady-st",:.e points, and smoke numbers greater than 95 (i.e., nonvisible range) ~ere expected. ~:\G I \E "\\D EHS PERFOR~IA\CE Overall, the P-4J engine performed favorably with the f iva fuels tested. Even though engine performance was low due to general engine compo- nent deterioration [II, nothing detrimental to the engine or the EllS _:as detected during testing that could be attributed to the use of dlternate fuels. The entire ",od i =- icat ion system. test program ~as run ~ithout any :0 "i ther the combustor or cont ro 1 Although not part of the test plan, cold starts Io,ere made (using gasohol (ET-3), ERBS, and unleaded gasoline) .. ith litcle problem. Ignition .... ith diesel fuel and shale Marine-diesel ""as possible with a Io:arm engine; i.e .• ""ithin '~10 mlnutes after shuting off the engine and .... ith tube temperatures between 300 and 250°<:. The latter ignitions, hoo.:evex·, ""ere very sooty; smoke ... as dsible ·for several minutes tmtil the engine warmed up. Pressure and temperature data did not indi- cate any deterioration in combustor or preheater performance. Pressure drop ratio across the combustor and heater head is sha.~ in Figure 14; 3.0 8 2.0 0:: J:, E 0 u (l. '1 10 • \JnIM.,.., GQoo,n.l· 2 'X ER8S "2·23 - .: 2'J II a lJ "d"S : »10 parameter: i.e.' P L i - P PH i '1- R T . U I..: 1 ------- -,-'-~--" ,,-,here: P Cl o . PHi '1 R u P . cl p" 2~~1:\ c i .·..:e [n:versal g3s constant Combustor 1:1 :et : e~pt.~!,"dt ',!:-~ ~\I;' ~olecu1ar .. elght A Ef!ec:i~~ cpen area of :ambt~~to: ce . ) It should be pOInted out that the V4:~t> 0: ~ actually calculated was ::01. the totdi "'ciSS :- '010' since it \,;as calculated llSU1& ~he \"l~lu~~trlc ~::;R va 1 ues ~ i. e. : l1 = ~!fuel AJF (1 + ~~~) (5) \Ihere ~fuel is the measured fuel f1010:. Data ax·e shOlo:n for the mitial and ::n31 gasoline tests, aswell.1s the test ... ith ERBS fuel ,run tOlOard the middle of the test sequence I. ;he data show no change in combustor;heater :,ead effective area, indicating no plugging or damage to the components. Ins~ct ion of the hard""are after the final gasoline test did indicate SOOIe pluggin~ and thermal dam.age of the heater tube fins; however, the open fin area is large compared to the c0t4bustor area. and any change In overa 11 --------- ' .. IB .... U. ............................... -c-.......................................................... III .................... ... ____ 7 • _ pressure drop resulting from this damage will be within the data scatter. Figure l'i shows the pressure drop (in mm H~O) dC!~SS the combustion side of the preheater. ,"ine rirol .lcrOSS ~he 3Ir ~ iele ... as not measured.) 1(," ~ ... ;~S fIn\.; !'unction In Figure 15 no~ includes rue: flow as ... ,,11 as air flow. llld ~ppro)(imate F.GR :ndsS :-low. A,:;;alrl. :here is no t~\' ~(icnce of .lny ':hc1ngp !n prpS~llrp ·irap chtlractE'rist l.CS bet,,-"I{~en :h!' ::llt!.ll .lnd :'lrtal t.~s'"" ::,.equ.pnces. The pos:·:,~st :;1Sp\~C: lon ij . .! :lot f('veal . .lny p!u~ging ,)~ ::.f1' ;:rt·hp'ltt?l~. i~ h1d ~)!"":~ifla:ly b.~.'Tl fp,,,f{·d. ~·~.;ure :!1:~ ;':-:!If.!r ,"x,tmp:" )f :.he _Jns:st<:ncy Q! :~~e ?!"f'hpiitf'r p~rtor':,drJ.( ... e ind :hp. ::lSt~n~l:!\"l:'y :0 t~~p.! :Y?P. :-:Aure:e i:~O ~hrn-.:s ::H! :'emperd:' ';'~f1 ,.: ~:! f'rt"r:c.p L! :)<;.., th~~ ;.()r.;hu~t :01':. ~ ~ de d t :. h ("" ? : f" ~\.' !: t~ r ::J r :. ~.... : !'. : ... : .l 1 H.d 7! n 1..11 ~l~O.:~lt~ .... ~ts. UH! "'~f" ... f' ... ~ ... '.,.:~~ • ...;,l .... OIIO: ::~-'3i ! : .. :... to: : .• ~: .;,nc .... :;c :: ~ ~ .... :- .. ::~:p .. ' t t'~j:)":' !.: . -;,. :-: .... p : '. ·.~~L-~::iR 1" ..... :-. ii' \) ~ : :.+" ~-;I':.t' i:~r ~,)r I ..;: \ ~r: :: 1 ....... : : : : ,':- f·: ...• ':-, 1 :".: .... ~ :. :-:.. j: -; .~ •. ... i:-. '':oC- Fi~. l) ; .... • 0 . r~ ... " r. ... : ... : --. . __ • ... :."" .•. -.pt'!'"- i:": ::. ' .. J:. :::f' ----------~ --------:--~,~--------, :~~~ ~ :"SS - ~,...~ JdSCi·re ;;t,e.~t) ------------------- - J 30 Pr\!ht..·att..·r ?r'l.·s"'llrt· :)r.'p \.· ... l!!1bust i,on \ ... lS Si.Jt.' P- .... 0-~-1 \ .\ltt.·rn~ltivt! FU'l.·l:"O Tcost 100 Sl~MARY ASD COSCLUSIOSS The mu I t i fue I capab iii ty of the P-40 St i rllllg engine has been clearly demonstrated. md ~he emi"sions re·sults have shown that a single combu- stor and EGR schedule can be deslgned to meet the CVS cyle eeissions requirements .... hile burning a \-arietyof liquid flleis. There \o.'as essentially no difference in \Ox levels .... iLh F.GR fer ~he five fuels t!!sted. Altholl!:h par'lmetr~c studies of :he magnitude nec~ssary to establish \OX correlJt lon5 as ~ funL- :. ~on -:;i ;. j:-~ou!'J :::is ..... :10 .:....:Jmb~s:.Qr rd:-.lmC~(·:-~, .. (!:-~ ... ell beyond :he scope af ttlS tnst, raugh ~orr~- 1 ,1t ~ons 'w"e-rp m(lde .. :!.h some "iUCCP.SS ~ thes(' ':<10 b.~ uspd to t'st.lbl:~h pr-e:lm!nary :':3R (~~)mbll ... tor r.~qu::-pments !or :hp t"?gradf'd ~orl : '·nK!n~ StfOcldy"s:,l:.e ':C H:rl He .. ~i~~iO~I:-' :1:',1 ::,.~:~ l .. ,"1tIP ~~dt :.hlS ,""nOll>.! :':0:' t)rt!~.·nt .1 ;;r8~;:.·m .~. :'~." \.0, .• ·ml:o.~,,;.ons rf·qu:remf>':-.!.~ .,In ~;p 1cL: .... ·pd; .... J ..... \'- ..r. ·.lao.;tdbl
2. 1982. Engi:le Erniss~ons '0. ~:ASE:00Ek37. Test June 101 == 4. Donavan, P., and Cacltette, T., "The Effect of Ambient Conditions on Gas Turbine Emissions - Generalized Correctioll Factors," AS'1E Paper ]S-GT-87, April 1976. 5. !iu'lins, P. '1., and '1archionna, ~. R., "Evalu- ation of ~OX Prediction-Correlation Equations for Small Gas Turbines," AIM Paper ~o. 76-612, Julv 1976. 6. Su:livan. DO. Ao, "A Simple Gas Turbine Combu- stor ~OX Correlation, Including the Effect of \'itiated Air," AS'1E Paper 76-GT-S. 'larch 1976. .",4 'M n Stirling Engine Materials Research at NASA Lewis, MTI, and USAB ABSTRACT --A :oordinated materials research pro~,am for the automotive Stirling engine is under ,,'ay at NASA Levis Resear:h Center, Mechanical ~echnology Incorporated, dnd United Stirling Swed·,n. The programs at the three or~anizations rave empha- 5lzed the hl.~h-:~mpt~rature matcrlal~ aS$OC tated ",itn trlt~ heater head. NASA L~\ollS ~.as iocused ,,)n : reep-rupture propert ies, hvdro~e'l permeat ion and embrittlement, oltidation resista.1Ce, and simula- ted eng,ne conditi0n eiie:ts on heater-head tubes. ~TI has ~een responsirie tor fatigue "valu,H,on and tatlllrt> analv.,s. USAB has been ,·valuat.ng mat£rL1ls In t>n,;:ine .)peration and c r"ep-ruptllre t .. sts 0t Int,rnallv pressurlzed heatt'r-n"ad tub,' a I bws. nrt"!>-1"'3~.p..rilv.ide$ itn • lpdatt' .)i resedr.: h c c)nuU-: ted at the three orga- ---~ ~HE STIRLISG ~NCISE I~ under 'nvt'stl~ation .n the :HH.·:,SA,SA Stl.rilng ~~ni'i.:1t::' ?rl..)Je~t as an alt~rna- ~ lve : ........ :~e :.:;.tcc:.il ::Jmbust 100 en~l.ne tvr auta- :nl.)tl.V~ tlipplL~atL0ns~ ~~~\,'el.Jpm~nt 1.)[ the SClrllng ~!n~t:le lS '~nt1t~r wa', thrl..)\l~h 1 ,:~"'nl,.ra.:t Wlth ~ech .1nL:.3~ :-'l:~('nn0l0-Z:v !n.: ..... 'rp,..lrated \~TI) dnd a sub- :.'t1tra:: ",.tn vnlt .. ~ :.. ...... s. the t> .. at"r head' was concluded to be the ,"OS[ :rltl:dl component. Prunarv gaps that ~rt' 0una to requlre research and Jevelo?- ",ent In::luJed ",<,:h .. nlcal propertv data on .:alldi- date allo~s under St,rl.ng .. ngtne operatlng .:ondition;; cOlllpat,bllltv, pen:>eat,on, the effects 0[ the h:~h-pressure hvdrQKen working Wo-k perioraed tor the U.S. Departae3t of Energy U lder Int,er&p'enc v Ail reeaoent DE-AIO 1- : 7CS510"J. 103 Joseptl R. Stephens National Aeronautics and Space Administration Lewis RO!$earch Center Cloeveland,OH Micbaef T. Cronin Mechanical Technology Inc. Latham, NY Erik Skog United Stirling Sweden Malmo, Sweden fluid on the mechanical properties of tube and ~ast alloys; and the effects of substituting less ~ostly, lower--strategic-eiement-content alloys for alloys containing the strate~ic metal cobalt that are now used in orototype engines. A coordinated approach by Lewis, ~TI, 3nd USAB has been undertaken to overcome the materi- als problems associ3tej with the Stirling engine ior automotive appLi.::ations. Lewis has focused on base-line ~re~r-rupture properties of ~andi date alloys for toe c~linders, regenerator hous- ings, and heater-head tubes, oxidatiofi resIstance and ~~drogen permeation of the heater-head tubes under simulated engine operating conditions, and the effects of ~igh-pressure hydrogen on ~reep rupture. ~TI ha~ been responsible for determin- ing the fati~u~ properties of :andidate cast al- loys for the c ... l inders and regenerator hoes ing s • "atigue testi~ in air has been completed and tests in high-:>ressure hydrogen are under wav, t:SAlI has been operating a P-40 "ngine (prototvpe automotive Stiding e.l~ine) Clndt>r conditions that are antic ipate! to exist in the upgraded Mod I versions iJf th~ automotive Stirllng engine. Can- jidate heater-,ead tube alloys are also :'eing :reep-rupture :ested b~ ~SAB using lnternal hel- ium gas press;u:-es at temperatures to dSC>° C. This pa.,e,.. sumaarizes the materlals researc h conducted by L"vis, lffi, and USAB durin~ the past 'lear. RESULTS H~ATER-.~AD TUBE ALLOYS - Candidate heater- head tube alloYi were evaluated ln t~ Stirling t>n~ine material. simulator rigs at Lewis. Tube Deg,ra.:at ion - NASA Levis has operatea Stirling engine materials simulator rigs for ~ yr to "valuate :andldate tube alloys. Engine .:ondi- t ions of te\llli,erature, pressure, enVlronment l.:oar- bustion gases and internal hydrogen), operating ti_, and .:vclic operation are slIlIulated 1n these rigs. The en~urance tests ln the Stirling engine ~terlals SllNlator rigs provide a Deans oi rank- lng :4ndidate alloys. rime to ta~lur~ (tube wall .. .. -- • rupture) is the primary criterion for such a ranking. Since helium does not permeate the tube walls (nominally 0.9 mm thick) at a measurable rate under conditions used in the rigs, helium gas pressure, and hence stress in the tubes, re- mains essentially constant during testing at 820· C. In contrast, hydrogen permeates the tube walls during each 5-hr cycle, thus lowering the gas pressure and the resulting stress in the tubes (although pressure losses are substantially reduced by hydrogen mixtures containing 1 per- cent C02' Failure tiffie with helium (i.e., the higher stressed tubes) has thus been selected as the failure criterion. In table I, the perfo .. m- ance of l7 alloys (compositions in table II) is arranged into five groups based on the alloy lives in a 3S00-hr endurance test (the design goal for automotive Stirling engines). Two of the alloys, CC'-27 and Incoloy 901, had no fail- ures during the 3500 hr at 820· C and IS-MFa pressure. Two alloys, Inconel 625 and W545, had average failure lives (based on four tube fail- ures) of 285l and 2776 i,r, respectively. Two hy- drogen-filled W545 tubes failed at an average t lme of 2772 hr, indicating a possible hydrogen embrittlement of this alloy. One alloy, 12RN72, :.iled between 1500 and 2500 hr. while all remaining allovs failed prior to 1500 hr of t es t l ng. On the bases of the initial 3'i00-hr endur- ance test, oxidation resistance. tube formabil- itv. and resistance to hvdrogen permeation, CG-27 was selected olS the leading candidate alloy for :l"tomotive Sti,rling engine applications. A sec- ,'nd 3 SOO-hr endurance test was c onduc ted at Lewis 'Ising vnlv CG--27. Sixteen tub,es were tested at ~~O· C an~ a ~as pressure of 20.7 ~Pa (the esti- -nateJ peak prj,ssure experienced in automotive Stirling engines). CG-27 tubes sustained this ,.>"treme test pressure for 3500 hr withollt any : .• i lures. Hvdrog€'n degradation l,f :andidate td)e .11- ~vvs in the Lewis ri~s 2 an ~e est imated trom th" ratio of time-to-failure with the H, • 1 per~ent lO' ~as as ~orapared with t uoe-to-faIlure tvr ·,,·tium-filled tubes. As described previously. :ailure of tt"" helium-filled tubes was expected ~" <.X:cur earl ier sin.:e a hi~her internal pressure was maintained throughout the test. It, however, tn spite vi I",.'!."· internal pressures due to ~lii~s10nal :l)SSes. ~,vdro~pn je~rad~d !he hi~h temperature strength of anY vi the alloys, iail- 'Ire .:ould ()(:,;ur ~arlit:'r 1n the tubes .:ontaining flo • 1 percent CO,. Table III indicates that t ~Ul .... llovs e'l(hibited evidence of such possibl€' hydrogen ~egndat lon. These alloys are lnconel ~'iO, 12RN72 cold worked. W545, and 19-9DL. The rat io R of .. ndurance hie for H, + 1 percent CO~ tubes to that for helium-filled-tubes ranged fr~m .1 low of 0.64 for Inc one 1 750. a nickel-base al- lc)v, to 0.38 ior 19-9DL. The two alloys that had nn failures iil 3500 hr. CG-:'7 and Incoloy 901, "ave unknown I~ values. In beth cases, however. ;",drQl;!.en deKr~dation does not appear to be a problem. ,.--- Hydrogen Permeation - The Lewis Stirling en- gine materials simulator rigs also provide a mea- sure of hydrogen permeation through the candidate tube alloys. The alloys are presented in three groups in table IV for the H2 + I percent C02 gas mixture. It has been postulated that a permea- bility constant, lower than IxlO- 6 cm2/sec- MPa l / 2 will be required in the automotive Stirling engine to minimize hydrogen recharging to acceptable intervals of 6 months. This figure indicates that all candidate substitutes for the cobalt-containing alloy N-155 (except 253 ~. W54S, and 19-9DL), have permeability constants that are less than the required limit when H2 + 1 percent C02 is used. This presents the pos- sibility of using less dopant in the hydrogen since 1 percent C02 in the hydrogen lowers the calculated engine maximum power output by 7 per- cent. However, further studies are required to determine the optimum dopant level. Some insight into the mechanism of reducing permeation by hydrogen doping is afforded by the ~ompositions (table II) of the various tube alloys that ~ere. luated. Alloys with good res istance to hydrogen permeat ion, in genera I, contained significant ~uantities of strong oxide- forming reactive elements such as aluminum, titanium, niobium, and the rare earths. As discussed in ?revious CCM presentations, o~ide film form,lt ion on the tube internal surface, as a result of doping the hV + 1 percent CO,.' This figure also 5how; the .. ffeet of temperature on pure hvdro~en "nd doped--hydrogen ?ermeation for the modii'eJ l-l-9DL allov. Tht'se initial rt'sults suggest that alloy 20ID1>osition lS an lmportant fa::tor tn r<'- clueing hvdrogt'n permeatlon in h~ater-head tubes and that :.inor addit ions _,i rE-active _tals :nay ~e ust'd to reduce hvdrogen loss irom the englne. • / Table I - Endurance Test Results [Temperature, 820· C; pressure, 15 l'Pa; g4s, H2 + I " CO2 U\d helium.] Time to fai lure. t. hr t :> 3500 2500 < t < 3500 1500 < t < 2500 750 < t < 1500 t < 750 CG-27 Inconel 625 12RN72 Cold worked 253 MA 19-90L !ncoloy 901 .,45 12f 1 ;·~o ')ar. lCr:~ : nc:ne 1 713 :n~~'nel ';01 :"'~''36 Compos I tion. wt :, ~~ ! ~; I ~~ 20 2~ l:~ I ~j 1.5 0.5 .1 .40 3.0 11.0 2+-1---1°.15 0.15 N S.; .6 .- .. - 1.5 ! :.5 .05 J.OI 3 ~:~ ~:~ -.. - :~5:~ I :~~ ).015 a " b I .15 .3 i .2 2.9 .08 a.08 S 54 ;~ ,6 1 S ,:~ ;; ~~ ~~~Il:~ .4 1.5 1.4 .40 1 I.S ::' 22 40 .,-. 14.0 .29 1.7 .5 Il~ :~ ~~ :~ .~7 1.0 2.8 :~ 2:! I I , "1 ' .) 1.1 .6 I.} .4 L2 .3 1'1 1952 .:.3 3.1 S.C .41" '3 I . C;; ... 1.4 I'~ 1.3 "-' .1 v.02 .. .09 0.7:« .08 0.08 ,-a .04 .89 .3 .04 .05 .05 1 14 I'} ;;0 ·-·.5 .? ---- ---'11 1·. Z 4 '_~-.2- 'I' ~.; I':: 211 ---Log'"' .... .~.5 : I!" 1_' I '1", .;< ., .•.. .38 .id i __ . ____ ...,.... _-L----.L-. __ _-'-_'--- J ,. ~: ~ { :.j ,'" • )7 .J5 ~::-.t' ~:",dr0gen Jegrdudtion ,::f t'ressu"~led TubeS :?ressut'e .. 15 ~~ .. ~ r---------.... --. I I R> 1 ~------r-----------t---- 1 .~_('; jl J.,?KN7? ~n(onel 601 ~"'(:':J\ "":I~ 1_'s3 ~ A23-; 19-90l. ,645 R < 1 \0.88) (0.35) ! "S-ISB SanluG 31H 1211"72 cold wor.£" ! '~r- 'looL 0 Table IV. - Hydrogen Permeation [Temperature, 820· C.] r Penaeability constant, 'P, c,.2/sec_l'fi'a l/ 2 'P < 0.1<10. 6 0.lxlO- 6 <'P< lxlO- 6 lxlO·6 < 'P < 1 O:r. 10-6 -- CG-27 lnconel 750 '253 HA l2RN72 lnconel 718 1645 lnconel 601 HS-l88 19-9OL I lncoloy 901 San icro 32 Inconel 625 lncoloy BOOH ~ Sanicro 31H N-155 A286 i AI , ~-.- 100 ~~----·----:aoo~-·----~oo TIME. hr Figure L • C~id oxidation:JI I"Iodifit. ~ ~ ",- E u S; Z ~ '" Z 0 '-' >- ~ a> .. ~ "" ~c.. 20 I'l-IOL - Q 5'ul; PURE Hz 0 - IHDl; '? - 1'(02 . 5 ,--_._--,-__ ~ ____ L ___ . __ ~~ . 85 . 'lO • Q5 loo L 05 l. Hlk 10-4 INV£IlSE TfMP£IIATUR£. : 'T. K-' L ___ -L-_____ J 370 Sl5 :(0() :05 650 Tg1PtRAT~E. '= FiqUl'e 2. - H~-droqen p!'rMol3t"3I'I ,n modilied;:""'tl()SIlion : q-'lOl allO'o'S- tOl This factor will be taken into conside.ration when choosing an alloy for the heater-head tubes. Creep Rupture - Sevpral iron-base alloys are under evaluation at Lewis as possible substitutes for the high (20 pe~:entCo) c'lbalt-containing alloy N-155, which is the heater-h~ad tube ma- terial used ;.n prototype and Mod I autolllOt ive Stirling engines. Figure) compares the )SOO-hr rupture strengths of N-lS5 and two ~andidate ~ron-base alloys, CG-27 and 12RN72. The heater- head tube alloy~ will operate at approximately 820· C in the upgraded Mod I engine. At the proposed use temperature the rupture strength of the CG-27 alloy exceeds that of the currently used ~od I engine material by about a factor of 2. The CG-27 alloy affords a substantial ~rowth potential and margin of safety. The 12RN72 allov is not as str~ng as the other two alloys. but'because of its low cost, adequate rpsistance to hydrogen permeation and oxidation resistance, 12RN72 is still under ~onsideration for the upgraded Mod I engine. Creep-rupture tests are under way in high- p ressurp hydrogen to eva luate hydrogen deg raea- tion of candidate heater-head tube alloys 3"d 2ast cylinder and regenerator housing alloys. Some p~eliminary results are available from the high-pressure hvdro~en tests, which are being 21..."ndu..:teti 'lnder a SA-SA ; Jntra..:t ... -it~1 ~l: R.t:"s~ar:~1 [nstitutr. Fizure ~ shows the results 01 hlgh- pressure-hydrogen ll5 MPa) creep-rupture tests at 760· C on two he.,ter-head tube alloys. The solid lin"s represent a mult~ple linE~ar regres- Slon fit oi the ~ir creep-rupture .lata, which are us .. d as a base line ior ~omparison with ;,ydrogen t~sts. These initial results lndicate that hv- .lro~en degradat ion has not occurred ;n thes .. two h .. at .. r-head tube allovs over the limited t .. st durati~n. High-pressure-hydrogen :reep tests are planned for CG-27 and 12RN72. CYLiNDER AND iU:Gt:NERATOR HOUSING ALLOYS - Candidate oommercia, iron-bas~ allovs and ~xp~r i"",'ntal iron-base al,loys w~re t'valuated at L~",is and MT·1 as potential substitutes tor the cobalt- ~as~ -allo" nov in use tor automotive $tlrling t·ngin~s. Creep Ruptur .... Figure 5 sho,"s a ~ompQrison ot high-pressure-hvdro~en creep-rupture data ~lth !>ase-l ine air data for two iron-base alloys. CIUi- &D and IF-SIS (table V), that do not ~ontain the stl'at,,~i: "etal ~ob,llt. CR11-6D ar.d XF-81S .lr" under evaluation as substitut~s for the ~obalt base allo,s HS-31 (currentl~ used as the cylinder and regenerator hou1,ing 05110, in prototvpe en- ~ines). ilydro~en d •• gradation has not oc.:urred in these allovs ovelr the time frame of testing. Anoth~r alloy' being studied is SAF-ll (table V); however, : reep-rupture data are not ~et avai lable for this material. Tensile p~~~ ~ Candidate substitute alloys for the cobalt-base alloy HS-31 are under eva luat ion at m'l, ,~ith spec ial emphasis on ten- sile strength and f'ltigue resistance. Figure & shows a comparison of the tensile properties of three ~ast iron-bas.~ alloys with those of RS-31. 108 All alloys were heat treated tor 1/2 hr at 1125· to 1150· C and then for 50 hr at 800' C :0 simu- late a brazing cycle and exposure at tne proposed use temperature, respectivel~. Results show that HS-31 has superior strength over the t~rature range inve~tigated. At SOO· C the order ~t decreasing tensile strength is HS-31. SAF-ll, CRM-6D. IF-·SlS. The ductility of all tite alloys is low. remaining below 10 percent elo~ation up to 800' C. !'atigue Lif~ - The lov-cvc Ie fati,.ue lives det"rmin~d bv ~I for HS-31 and three :ast iron- base alloys are shown in ti~ure 7 ior various strain amplitudes. The data were obtalned at 800· C by applying various constant-strain-range ~£ or alternating-strain-range 6£/2 amplltudes about a mean stress of ~ero (R : -1.0) '.>nt i 1 ma- terial failure oc.:urred. For rand01ll loadinR .15 ~~perienced in actual engine Qperation, straln amplitudes and ~orresponding ~~.:les must ~~ ~rouped to ~stablisn a finIte loadin~ s?ectruru. The rain-flow ~ounting ~[hod is on~ met~od :or a.:·:omplishing this. The rain-flow spec:ruru (horizontal 1 ines) represents the pred"Qlnant .:~linder-head manifold strain amplitudes and their ~orresponding frequen.:ies expe.:t"~ .)V~r an "n~ine lifetime of ),)00 hr. -:-he Cllrv~ ~~a"'n throu~h the end points oi :~"5" lin .. s 1S :h~ i.. imitink!-llf~ .:.qrv~ fo!' t.:-:~~ :';"1 :..:-'. •. h·r-n~..i.:! ~l:'~ t0ld. 7hc hi)(her jlarail-=~ :~..;rve lS :~~ ':t"'''':;''':.''- life ~urve, whose strain ampi!tudes nav~ ~~~n in.:reased by' a saiet~ factor ,.)'i :2 aoove ::'0::."10 "': the 1 imiting-l ife c',rve. Anv :aaterlal · .. ""50> J.1t3 points rail bel,)w the .lesl;:n-il:" :urvo> .5 :.In- sidet·ed unacceptable. On :h .. :'aSlS Ji :.,,, rd1"- i low spectrum of strai.n ampli:~des .lnt 1~ :"a:,,-! in the :vlinder manifold. 311 the 3110"5 :'a ... " suffi..:: ient 1 iv~~; to ;ne~: the jeSl~n .: rl:~rl,"':1. Failure ot :ast :vllnders and re~""",r.1:·c housings. due to hi~h :v; Ie iat1~ue ,Her -."':.:- lng from ..:yc Ie pressure variat ions ,,"It': - "~ ... ..;~- ~en worki~ iluiJ, is als0 .)1 :~'nc~r':1 ..... .... automotive Stirling ~n~lne. F3ilurt.~ 1" 1'-40 hea~er h",ads !>v ~I .,ave ~nown .: ,: ,~ ", :: rack -;trlations in the man).toiJ i:-··,i ... : ":d:-.:: .:omponents. Relativf! fatl~u~ pr~~:J't'! ~ :t: .... :~>:er ~ined bv ~TI are .hovn In :ne ~a1~" ,: lLc~m. :l~ ure 8. for HS-31 and three lr '''-~a'c : ,,~.-=ljat" a lloys. The Ha igh d ia~ram 1.., 3 ~ r..l"r lC a. _tho" that is used to show the i"t":-3~: i,'C· .'; ,...,an :-;.tr~ss '.11th alternattng '?::-- ...... :"_ln~(", :-~~ ,,~r~S5 values shown :o("respl~nd :.' . ,:,:,:·, .. tLons .)r :nean stress and alternating ~tr .. ·;s :-.j,~'" that result in a fatigue life of :\), : ... : :"5 :c failure. The points for each _,: til" :hr'ee R values ana .l specific allo, are :.)nnec:,,~ .:,~ straight lines to torm upper bounds. '~er~10re. ~ny ;omb1natlon 01 mean stress and lit~rnattng stress range that falls below a parttcular INter}al .:urve w1l1 r~ suIt in a 1 ife ~rNt<'r than 10' : yc les :.)r that parti.:ulal' mat"nal, while cOUlbi.nations :.111>0& above the ;l'rve:s ,,111 result i.n lives less tt\an 105 cve l~s. A .: .,..ariaon of the data in =- l~ure 11 fol' the :v~r allo~s at 800· C shovs that HS-3l has the highest ReF strength. with SAF-ll only $!ightly / 0()) ·00 ·f W)~~ATUR! ~ .'00 •. )J • .. -=;Lo'~..\. ~ ..()t:...rt!' '.'1:"' .. j,' J~ .. ~~" "1 C~(lOtaatt "E'~r ~~ 't.,;CJt lillO'o\. • ~ .... OIII~f ..it I .. rt" . f'W......,..~ ...... \ly) ~.... ol\\.t;Ji :) : .... \w» ... ~ ....... 1i1 ~:::o--~ -- It' ., , ..... ,' . ct· ........ ... , - .l" II"'" .'" '\J!'~ 1 .~~.. - ",. V .. ,' -.., .. ~.jI ....... ".\ ",:; t, ~,\ '\,-".~. ' •. 109 I I f ~ 110~ "'5- j 1 'abl~ I •• :00Il00\1tl0n\ of Cut Cy\,_r lnd ~'!~I!rltor ""Ou\ '"9 ~ 1101\ ,~ ! : r [ ~, I :0 ["n I 5, ! ~ I Cb I • . ~QIIiCK)51tt()f'f •• t \. i .~ 25 ! 10 55 --- --- 7.S 0.5 ~'51 ~.S :.14-60 .,3 ?Z S --- :.0 ., . , 1 .. ,; 1.0 1.J ' .v S;S _11 I 17 2J 16 - - - .~, .6c 12 .6 j --- ---IF -d 18 ." IS IS -.:.t.' 1 .3 : .5 .4 -_ ..... .. 2 -1O >M" "'" ~~>o .J;e""""""":::! " i-=---.1. -::t:::::::Q:::~~ ; 00 :00 100 Q) '(Ij .00 :00 tll lIJI) ?L\,!~RATJ.;Rt ~ • 'qurt a ?t1"l\11f .)1"-.,1"\ t1 canOtlili- c,un4E'r JJ"IC 'f'9'nffatOf "'OU~ln~ il'o<. 1 ;; :5 .- 0.: ::E "" ~ ~ J! - () ~o L- :o:i CJ J \ ..... A ... .\t •. tl i.i\, N) .! ~ I~rt? ~ atl~ or~rhf\ ~ (~lMtt ( .. ~H''''' ~n(J "t·,Jt"'lf".i ·01 "w)."t.Q .tI'0'-4\ ~t"r.'IOtra':u'. '!ljf)f 110 3 ... _--- O • .)()3 I .l .0 . lI .. h' 'I "'~ar .~I(!)\'1rjtf ... l.~~r !M·f~rf'.:Itor "".)< .... t.; d'~~\ 'I?'--(\It'fdt ~r" (l)C''' of' -:..( f'\ ~~ 'a.i'J,t> 111 ~ ...... mg ....... m."""""""''''''''''''''''''''''''''''''''''''''''''''''''''' __ '''' __________ .. __ lower. The remaining two iron-base alloys, Xf-818 and CRM-6D, have lower HCf stren~ths. Design ~hangefi; in the ~od I enl~ine, as ~,)m pared with the P-40 engines, were focused on re- due ing the mean stress in the manifolds of th· ~vlinder and re~en'!rator housings. Success in s~bstituting any of the three ~andidate iron-base alloys will depend in part on the resulting stres~ ;ombinations that these ,omponents exper- ienc e in Mod I eng ine tesn n~. Experimental !~~ - Candidate iron-bas .. alloys are being evaluated by Lewis and ~TI as substitutes for the cobalt-base alloY HS-31 now in use in Mod I em: ines. As shown by ~l, ten- sile strength and fatigue resistance are lower for the iron-base alloys than (or HS-31. fig- lire 9 shows a complu"ison .:>f the 3500-hr rupture stren~th at 775 0 C (the upgraded ~od 1 cylinder and regenerator hous ing use temperature) for HS-H and the iron"·base alloys SAf-ll, XF-818, and CRM-6D. HS- 31 a Iso has bet ter creep-rupture strength than these iron-base alloys. Results based .:>n very limited data are also shown for two experimental alloys: EX-4G, under development at Pnited Technolo;~ies Research Center (UTRC), and EX-76, under development at AiResearch Cast- ing Company (ACC). Both programs are contractual with Lewis. The UTRC alloy is in the init ial de- ve)opmt'n~al stages and the all.:>v exhlblts pro- mising 0 re"p·"rupture propert ies. The ACC program has been under way longer and the alloy has rup- ture strength superior to that of HS-31, although its rupture ductility is lower. Continued eval- uation and alloy modifications are planned for these two programs. ENGINE TEST:NG - Laboratory testing at Lewis and ~l is used to s.;: reen potent ial : andidate allovs and to identify those alloys that offer the ~ost potential as" substitutes" for currently used ~obalt-base or ~obalt-containill6 alloys. Actual engine operation ~ives a more :ritl~al evaluation of :andidate alloys and can provlJe a means of ranking alloys under :onditions that will be simi lar to those experienced in upgrad."d ~od I engines. USAB is also eval",,<,ting the can- didate alloys that appeared most promising in laboratory testing bv means of P-40 engine (3 prototype" engine) te~ts in one ot their te~t :ells located in MaltUQ. Sweden. Figure 10 shows the .:ombinations of alloys that were selected for fabrication into eight quadrants for evaluation. Cy 1 inder and rege~,,~rat")r housings 'lere fabri~ ated froUl the cobalt-base alloy HS-31 and three iron- base alio"s CaM-6I1, XF-818, and SM'-li. Heater- head tut>e~ were ma.tched with the corresponding cast a lioys as 1 is;ted in the figure. Tube alloys were a nickel-oase alloy. Inconel-625. and four iroll-bas'~ alloys. Sanicro 12. 12RN12. CG-27 , and 112 Sanicro 11H. As ot September 1982, a Lotal ot 14)) hr had been accumulated on the heater head of the P-40 em:lne. The test plan :alled iJr t .. sti~ at 820" C and a pressure varlation !rom .. to 7.5 !1Pa for 1000 hr, wlth inspection of ~he four quadrants after 500 and 1000 hr 0t opera- tion. If no severe failures oc~urred after 1000 hr, the pressure :vcle was to be made more sev- ere (variation from .. tJ 9 ~Pa tor an additional 500 hr). A further increase in pressure varia- tlon was to be ohosen after 1500 hr 0peratlon if no severe failures had ~~urred. Test result5 (0 Jate (ti~. ') lndi~ate that Junn!! the tirst 500 hr (pressure variation of ~ to 7.5 XPa) of operation, quadrants 1 and ~ werp iree from anY detec tab Ie fa i lures or .:: r'le ks; quadrant ~ i'xh I b- ited .:: racks in the manifold area Jt the re~en erator housi~, and there were so~ posslble indications of .::racking on quadrant 3. Testlng was oontinued on all four quadrants. During th~ 500- to 1000-hr testl~ period, braZe-jOlnt tal~ "res occurred in quadrants 1 and 2. These quall- rants were temporarily replaced ~v quadrants) and 6. After the pressure variation was in- ;rcas~d (4 ~.:> 9 MPa), two tubes fail"~d in quad- rant ), which 1JaS replaced with quadrant 7. In addition, it was determined that quadrant l ~3S ~}perating about SO~ C hi~her than quadrant 4, S0 these quaurar.t -;:h"lsitions wt: .. r~ ,,:,·(.:h~rl):~1"~.j •. ~, Jat€', no problem.s have J~en ..:aoc0untered With quadrant -+. En~ine testing is '::c1Otinul~ "1~ planned. CONCLUS IONS From Stirling engine materials resear~h :,)nducted at the )lAS" ... ewis Resear:h C"ntt>r. ~t'chanical Technologies Incorporated, and United Stirling Sweden, the (ollowing ':0OC )uslOns wer" drawn: 1. The leading hi~h-strength .:andidate heater-head tube alloys are (G-2;. In~0nel 1)2)" and 12RN72 on the basis 01 ;;tirling en~ine mar,'- rials simulator rl& tests and stre~s-ru?ture t .. sts periol~d at NASA ~ewls. , The lead ing l.:>w--.: ost .: and idate 1 ron-bas<' o vl inder and regenerator hOUSlrtg allovs all hav., shorter fati~ue lives at 800· C than HS-31, the ;obait-base alloy now used in the Mod I engine, but some ot these lives may b~ adequate ~n the ~asis of ~TI-:al:ulated strain amplitudes in ~ylinder manifolds. 3. Engin.? evaluation at United Stirling S~den of .:andidate heater-~ead alloys under ~on ditions simulating the upgraded ~Iod 1 engine has shown tube-manifold bra~ing to be a problem area. Tests in the P-40 englne at 820 0 C show that al- loy 12RN72 may be stress and temperature limited. -- • ~7' L .'iJ.-- l~!! •• ') l' .25 ,J'\fl 2;'10 RA 105 40'Hl 60'loRA l J ----'-----"-- ~ 'qure'" .. t"j))·~"Our r·;ot,.re stren..:1tt' tl)( (and,Gate (tlln . )verall "'n~lne a.nd Lirivp 5yst~m ~fiicit~ncy \ratlu L)t po'Wer to ,,'heels to :uel in) is 30 per- \.·~nt. The study also includes the tuel t"l-:-onomy ~ensitlvlt~ 0t the Stlrling h~draulic svst~m to ~v$t~m w~l~ht. nllmber 0t transmlssi0n Shllts, r~jucPl: Jra~ ':C't.>"ttlClt>nt •• 101...1 \'ar\'ln~ \.'t·hil'lt~ ~'t'rtl'trman":t~ rt·qulre!I!.::.nts. ----' ::-i ,,[CU,T YEARS rh.- :-iASA 0,,,""1< ""sedrch lO"nt,'r '1as \. .... )nriu~tl!d a nllmb~r ,-'t ::>tlrllng t."n~lnt.· lnvt.~S !:lzatll..l!1S :1..")f.J varl~t\' "t potentlal appll..:a- ~ 1.I..H15. Thpse ~)ct iVlt lrS have lncludt:!'t.l tht;" )'t'Pdrtm~nt ,,! ::Ilt'r~v's Aut0motlVt? StlrlLl~ eng tnt· . t·\'l:.~~,-'pr;h.~:;t Pr,) !t>(t :' .. ~ln~ ... : .... lnu ... !,:!:.·,j ~". :nt.. :X)t: ... l:tll..-e- (It '''~hl..:le ,1n'-.1 t.t1gl.ne k&I.>, :t:.'("~H10i'.h~Y ..... rv\.·10pment .Jnt.l Analysts DlvLs10n, .lna the ~A$A jtlrl1nK En~lne ~~cnn01J(y ~ii0rt spOnS0r~t.l )~ :ne SASA Hpa~quarl~rs (0nservat~011 ~nd F0SS11 ::'n\.·r~y :i~·stt!:ns 3rdnch I,)t the E.n~·r~~· S\'"st~ms DlVl- '1,)11. ~h1S SASA-ilmded ,'! tort .. oas al1ned at ""r\, .. ll..h'nl~ ~h~' ~~n~ral :it lrlln~ ~n~lne :~"..:hnoll..)~'./ .' ... l~1.." .it :...~\llS ..and. .lSS~SSl~ lts. .J.ppiicablli:'.· to J vdrl~t~ ~t appll~at10ns~ :-hlS stuJYt itA Fr~e-Plst0n Stlrllng HyJrau- :1": Jt"lVt:" :,..lr .\utvaf.J.bllt"s." ... as .:,]t"rl~1.l Jut dS· ?art ,Jt :h~ SASA-tut1l(l~~ eI. :,,)f"t.. r:lt." stu..:lV has ·Sumth.'rs 1..;1 "at'·~nth~ses J~Sl~natt." r~t~r 't""n("~s ..It 't""n\l ': ?dP,=,r~ 115 Donald G. Beremand, Jack G. Slaby, and David Mi80 National Aeronautics and Space Administration Lewis Research Center Cleveland, OH relied heavily Ott capabilities and information developed at Lewis under the various DOE- and NASA-funded activities. A significant part of the NAbA-funded effort has been directed toward the free-piston Stirling engine. The free-piston Stirling engine is in an ever- earlier state of development than the kinematic Stirling engine current Iv being (ieveloped \;nssurt!: IlllJ trom th~ .lc("umulat0r l.S ~Uppilcd : .... ' :ht" vdr!301t.'- J1splact>ment motO('-:>UlllP on ~"1!1.111': :w <,xpanS1Jn o[ the ~as tn ~h<, J.:("umuloH,lr. :he "Vrovidl~ the kinetic energy necessary to ac~lerate th'e vehicle to maximUtll speed (113 111 km/hr (70 _?h) ~n a level road). motor was then sized to meet the rate criteria with the scheduled The hydraulic a cce lerat iun accumulator pressure. To avoid continuous on-off cycling at the engine, a +0.69-MPa (lOa-psi) dead band was added to the ace .. lUlator schedule so that the engine would c.,cle oif at the top limit of the Jead band and cycle on at the bottom limit. For example, for th.> basel ine case shololll in figure 2, at a speed of 80.5 kIII/hr (50 mph) the engine would turn on when the pressure iell below ap- proximately ~o.o MPa l~900 psi) and would shut oli when the pressure reached approximately 20.7 ~a (JOOO psi). In view of the on-oU ~ngine operation, auxil iary power for both th .. vehicle and engine is provided by means of a separate hvdraulic motor operating off the accumulator system. This assures the continuoub availability of power for the vehicle accessorles such as power br'akes and air conditioning. It also pro- vides tor independent operat ion 01 the eng ine burner system, which will be reqUired to maintain heater-head temperatures at design values while the vehicle is operating but the engine is shut off. ENGINE SELECTION A.t pre-s~nt, there are no "nown ,lpt!ratlng iree-piston :it ir 1 ing eng lnes above about )-kw \~-hp) output power. Nor have any design stuct.es been prepared that would apply directly to t.le requirements of this study. Therefore, it was decided to .. st imate eng i ne performance bv ext rap- olating from existing large (30 to 60 kW, 40.2 to 80.S hpj kinefAatic engine results and factor- ing in the results of deSign studies that did ad- dress hydraulic output for tree-piston Stirling eng ines. It was telt that the best ~asis for this was to extrapolate indicated efficienci~~ trom the results of the DOE/NASA automotive Srlt"l:'ng en- -:ine pr~ram. The resulting method was to calc .... - late the indicated engine effiCiency as equal ~o 75 percent ot the Carnot erficiency and add ~!2 efficiency point for ~ptimiZing [he engine with- out any requirement for higher power, high-.spee-i operation. (The Mod r engine incorporates onlv a portion of the automotive reference engine ad- vancellients, and still the ;:>redicted indicated efficiency of the )1od I engino' i, 50.1 percl'nt. ~nly 1/2 percentage point below a value oi )0.0 percent obtained by using 75 percent of the Carnot efficiency.) Therefore, using a heater temperature of 762· C (1404° F) (assuming a con- tinuous lS-liPa <2175-psia) charge pressure for 3S00 hr of life} and a cooler temperature of 50' C (122 0 F') with 75 percent of Carnot ~it i- ciency yields an indicated efficien~-y ,'f 51.b percent. Adding 1/2 point for the optimization gives ~m indicated free-piston Stirling efficiency of >2.1 percent. Overall engine efficiency was then calcu- lated by applying a ~stion efficiency of 92.4 percent (2) and a conservative hydraulic ....... '?P ................. 77611· ................................... • ...................... DIll .................................................. . ;;. x :r / '" "- ~ ~ 'i' ::: 25 \000 «~- Gl) -- ;: :; ... .c!. ~ ~ ~ ~ :$ ~ '" ::: :~--. .. '" :wl N1) lO- !'\ .- :0 . l~ . 10 .------- -----.------ 10 10 Cl flO !O 100 120 ~HI(U SPIED. ""'", 10 10 CJ \0 10 "IlHI(U 'PIED. "'Ilh ; !Q\.i"': - tr:Kt ~ 1I\tItCle:~ Qt\ ~rtntbf prt1\Uf"f tacc'JmU~i\tof .... "'1.1\ "ufl~1 tor fia~lM 'ltlnI(Jt ,,8: • • Ta!>l" 1 •• Stirling Hydraulic Saseline Input and Output Par_ters (a) Input conditions Ace_lator ancl sUlllP ••• AYd11anie engine ~wer, k~ (hp) •• Average encpne efficiency, percent Ma.1_ dIsplacement of sca leo Vo lyo V·lO hyora ... he IIIOtor-pump, CI.3/re. (l"J/ rev ). Ma.1_ speed of hydr.u I it IDOtor·PIJllP, at 11 3 kill/ hr (70 IIlPh), rpm • • • • • • Total vehIcle inertia .. eight, "9 (10). Acc ...... l.tor lllaxi_ pressure, HPa (psi). ~C(u,,,".ator Ilini_ pressure, It'a (pst). Sump ..."xi_ pressure, "'a (PS1) •••• Accu"IUlator and suorol) volume, .. 3 ift') •• "'ator-pUOlj) shaft speed over whee I speed: D1rect connected •••••••••• Slngle 'h1ft •••••••••••• ::,edr j1r€,ct-drlve eff1c1ency, ;>ercE'l"'lt: JrOcln .............. .. >;19"·'1· ••.••••• Sh1ft eff1clency, percent. Tlre efflc1ency, percent: u,.bdn ......... "19h"., •••• Jra9 cO€ff'~ lent ;ronta 1 wenle leo drea. wi- . ttl) Effect 1 ... ~ .. flee 1 :lalUs, .. 11'1 \ In./. \b) Output :JMlt10ns ....------- "otdl n.'lc~3ullC sl!ttem .. '£'lgtlt. 'Q .:.; ~CCI.l1">wlcltor w£'lgnt .... g !:>/_ Slimp .e19nt. '9 \ l~; .. ~ 11 .. e 1 ;1ft! .. 11.9 : 1:> J .... ';olvo "IOtor-llump we'gtj'~. 1.9 llt>: I: 'etHcle .f.'leJht less l'lyaraullC oc;jstem -t'lgflt. " "'g (1!l •• a ............. .. :Iayton :yntaMara I"e: econoo:y. <"" II ter :"'''9): ... ~Qn.-):w .. J"::'d.n ... : 0m1l1nea '-------_. 119 .lsothe....al 39 (52) 43 81 (4.94) 4000 16J3 (3600) 34.5 (SOOO) 13.8 (2000) • 3.4 (500) 0.0683 (2.41) eat" 1.25 4.08 'd 1d O.~ 1~ ;.~8 l21 •. ~4i ,) .. 305 {~2; , '4 .604, ;.:~ I :tu; ,0 )8 ,1~ti! ,: : 13.1 !996 ' :",t .. v.~ :'0 .. S-t ;~ .. ~!, \.!~ .. ; J II :;.;4 c'>{J.6ilJ ---- • converter e:ficiency of 94 percent (3). The re- sulting overall maximum engine efficiency of 45.3 percent (ratio of hydraulic power out to fuel in) does not include auxiliary power requirements, which are accounted for separately. To better assess engine operation in the system. a hypothe~ical engine performance map was const ru(:ted (fig. 3) shmiing nydrau 1 i c power out- put as "I function of engine stroke and hydraulic accumulator-sump pressl'Ye differential. Typi- cally. the engine power output can be represented as a function of stroke raised to a power of 1.3 to 1.7. For the pUrp0$e of this study the expo- nent was chosen as 1.4. consistent with a l-kW (1.34-hp) output free-piston Stirling engine tested at the Lewis Research Center. Stable system operation requires that the slope of the system load requirement be steeper than the en- gine output slope. To provide this ch~racteris tic. it was assumed that a null-center-band pump, similar to the design of Toscano et al. (4). was used in the converter. Although this is a very simplified approach, the resulting map does pro- vide an indication of the range of operating con- ditions the engine might encounter in the system. The map indicates a stroke range from 70 to 100 percent of full stroke and a power range fro~ 58 to 100 percent of full power for the differential pressure range elf 10.3 to )3. i ~a (1500 to .. 800 psi). Examination at availaole :it irling engine maps. both free piston and kinematic. indicates that engine efficiency over this power range could vary as much as 10 percent. This 10 per- cent efficiency ra.,ge was then applied to the 45.3 p€rcent maxiroum efficiency previously esti- mated. This vielded an efficiency range of 40.7 to 45.J percent, resulting in an average engine efficiency of 43.0 percent. which was then used throughout this studv. HYDRAULIC SYSTEM [he hydraulic svstem i~cludes the high- pressure accumulator. the lov-·pressure sump. and the vaJ~iable-displacement motor-pump. which is. described below. In addition. the system re- quires some ancillary devices such as overpres- sure p~otection in the form of relief valves, filters. check valves, and a possible shut-off valve. Although It is recognized that these de- vices 3re necessary. ilo~ losses assLciated ~ith them should be minimal and were not accounted for in this report. ACCUMULATOR - The accumuiator system (accu- mulator and sump) was sized to store usable energy equal to the ~inetic energy of the vehicle at 113 km/hr (70 mrh). Accumulator maximum 01'- eratin~ pressure, 34.5 MPa (5000 psi) for the baseline caFe, was selected on the basis of th~ current state of the art of hydraulic motor-pump technology. The baseline accumulator pressure rat io",as selected as 2.5 (llIinilllUlll accumulator pressure of D.8 MPa, 2000 psi) to mi~i~ize vol- ume and weight and at the same tUlI/0:"0 Model V-ZOo Performance data generated by Volvo for a 178-cm3/rev (10.9-inJ / rev) displacement unit was acquired under NASA contract (6). These data were scaled doVll, as rel~mmended in (6), to the appropriate sma!ler molor-pump sizes used in this study. For the baseline system the operating pressure differen- tilll range, defined by accumulator and sump &aX,- imum and minUaum pressures and the +O.69-MPa (lOo-psi) de~ band, was 33.8 to 10.3 KPa (4900 -- I '-3'lkW 152 hp) I ENGINE OPERATING RA~GE 1,22.6kW I ~c.... (30,4hP)_~ ___ _ I ACCUMUlATOR PRESSURE MINUS SiJMP PRESSURE. ...-sysrr,o,· LOAD / REQUIREMEN1S L ___ L _______ ~ ___ ~ ___ ! 20 ~ 60 30 100 l2C ENGINE STROKE, PERCE"Il Cf MAXIMUM F!qure 3, - Operating map 01 Stirling fre~pi5t()(l engine with hydraulic output I Average M9ine efficIency, ~3 perCet'lt I 121 - to 1500 psi). l~otor-pump size was based on meeting the three acceleration criteria: (1) Standstill to 30.5 m (100 ft) in 4.5 sec (2) Accelelration from 0 to 96.5 kIn/hr (60 mph) in 15 sec (3) Accelelcation from 80.5 to 113 km/hr (50 to 70 mph) in 10.5 sec The first criterion was the most severe and thus determined the motor-pump size. For the baseline case this was a unit with 81-cm3/rev (4.9-in3/ rev) maltimum displacement. RE~ULTS AND DISCUSSION Fuel economy projections were calculated over the Federal urban and highway driving cycles and for the combined urban and highway driving cycle. These projections are presented in this section for the baseline system and for some of the variations investigated to assess sensitivity to various system and component design parame- ters. Included lln these results are fuel economy sensitivity as a function of vehicle weight, num- ber of gear shifts, and drag coefficient. In ad- dition, runs were made to assess the changes in fuel economy resulting from varying the perform- ance l"equirementH. The base I ine system component charac~eristics used in the study are presented in table II. To make a meaningful comparison with the Stirling free-piston hydraulic baseline syscem, the perfotTlance of a 1980 spark-ignition Phoenix with a three-speed automatic transmission \las compute~ calculated by using the same driving cycle and Environmental Protect ion Agency Clay- ton dynamometer computer program. The hot-start rc,sults for the free-piston Stirlir>6 hydraulic system and for the spark-ignit ion engine are shown in figure 4. The Stirling free-piston hy- draulic system, though several hundred pounds heavier, showed illmost a two-to-one improvement in combined fuel economy (21.5 to 10.9 kID/liter, 50.7 to 25.6 mpg). Going one step further, the combined projected fuel economy for a 1984 spark- ignition engine also is shown in figure 4. The Stirling free-piston hydraulic system combined fuel economy sho.,ed an improvement of over 81 percent over thil~ projected 1984 spark-igni t ion engine. Figure 5 shows the effects of substantial vehi cle we ight re·duct ions and a reduced aerody- namic drag coeffi.cient. For this analysis the ratio of hydrauli.c notor size to vehicle weight was held constant to provide nearly constant o :0 )0.5 m (100 it) acceleration times. White (7) projects a 907-kg (2000-lb) test weight as feasible in 1995 with current best technology, The Ford Thunderbird, to be introduced in January 1983, is projectE·d to have a drag cvefficient "f 0.35 (8). The combined effect of a 907-kg (;:000- Ib) inertia weight with a 0.35 dr'lg coefficient yielded a fuel e(~nomy of 31.4 kmiliter (73.S mpg), 46 percent higher than that of the base- l ine case. 122 For the baseline fuel economy calculations the total vehicle weight was taken to be 1633 kg (3600 lb), including a 272-kg (600-lb) hydraulic system weight allowance (accumulator, sump, hydraulic oil, and motor-pump). The baseline hydraulic system weigrt was then computer calcu- lated as 273.9 kg (604 lb). No attempt was made to correct the fuel economy values for the 1.S-kg (4-lb) differ'ence between assumed and calculated hydraulic system weights. This difference has an insignificant effect on the fuel economy. However, the use of composite materials for the accumulator and sump would reduce the hydraulic system weight for the baseline case by approlt- imately 77.1 kg (170 Ib), yielding about a 3-percent improvement la fuel economy to approx- imately 22.2 kID/liter (52.2 mpg). The effect on fuel economy of tile number of transmissir·n speeds and selected gear rati.os is shown in figure 6. One interesting finding of the study was that the system can achieve the performance requirements with a single-speed (no shift) transmission. It is apparent that a two- speed transmission makes a significant improve- ment in fuel economy on the combined driving cycle of about 12 percent, as compared with a single-speed transmission. An additional shift (three speeds) only increases the fuel economy about 2.4 percent more. Thus there is not much of an incentive to go beyond a two-speed trans- mission. As a result, the baseline case was chosen with a two-speed transmission. It should be noted that these calculations were all made for the same vehicle inertia weight of 1633 kg (3600 Ib). Some small reduction in the fuel economy benefits of the two- and three-speed transmissions would result if the appropriate weight differentials were included in the analysis. All of the calculations in this studv were based on an ideal gas and assumed the the~dv namic process to be isothermal in both the ac~ cumulator and the sump. This isothermalization can be achieved by filling the units with a high- surface-area material with high porosity and the appropriate thermodynamic properties. Obviously this requires larger total ac(umulator and sump volumes to compensate for the isothermalizing material volume in the accumulator and sump. This correcti.on was not made in the computer cal- l~lations since the degree of isothermalization r~quired was not defined. However, the results oi the comnuter analysis provided additional in- formation cn the operation oi the accumulator system. This allowed further assessment of the d~gree of isothermalization required and the a:lsociated efficiency and weight penalty. Even t~ough an accumulator pressure ratio of 2.5 was chosen for the baseline case, the combination "i pressure schedule versus speed. coupled with a +0.69-MPa (tOO-psi) dead band, resulted i.l\ a computer-calculated 3aximum pressure ratio over the coebined driving cycle of 1.S9. More impor- tantly, the average pressure swing was only about 1.15. Table III calculated from (5) shows the T.101e re~:~~e ...... . ................ . :nertla "€'lgnt. <9 (hj: .as€' vehIcle •• "'yQrdullC ,>.yCjtem no i jJUV I '72 ',600: 11;3; (JhOO' ~J td I. ""dJ. lmum ~.r1" .. c... ,"D ,I :"~e"'dge ~ff1:~o?!"I;:f .. Dt"'f'C€t"lt. :\((Jt"lJ ~ dtJr in..: 'J.fl00 - ~ J'> := >- :;; '" 'd J'> :5 >- J'> « x '::. 0 ~ nJ-- >- <{ '" a >- ::: 300 .. ?OO ' 350,- I "lOO ~ ?50~ ?(Xl - 150 -_. 100 • 70 :.- g 60-- E >. ::;: ::> ~ U 50- ~ a Z - :E 0 z 0 ~ ~ '" 20-Z oJ 1500 "lOOli II;{ Inlll .\fIGHT. Ib 125 DRAG COOfICIENT 0.35 417 0" E >-" ::;: 0 Z 0 ~ :5 I I SOl I ~~ i ! .It>f- I I I 44 f-- I ~2 L_ I ~ ! -r" ::;: :J Z :J ~ :5 20 - r THREE SP{[O. I TWO SHIrl rcer:t ...... _---_. 126 , . _ ... ___ ----"---.. _.....J lS 4.0 4.S effect of various deg;rees of isothertWilization (varying fill factor) on accumulator cyclic effi- ciency. EVen with ZE,ro fill factor (pure adia- batid, the cyclic efficiency at the average pressure ratio (1.15) was about 96 percent. At a fi 11 factor of 10 percent this increased to about 98 percent; and at a fill factor of 25 per- cent, to about 99 percent. These efficiencies, along with an estimate of the weight and fuel economy penalties associated with the addiLion of the isothermalization material, are shown in the table. This first-order assessment indicates the optimum fill factor to be of the order of 10 per- cent. However, this yielded a fuel economy im- provement of only about 1 percent, which may {lot be worth the added cost, increased accumulator volume, and complexity. Use of composite mate- rials would have only a small effect on these results since only a third of the weight penalty (isothermalization m'lterial plus accumulator con- tainment) comes from the increased containment weight. Isothermalillation of the sump, which handles only 10 percent of the energy handled by the accumulator, would have substantially less effect on fuel econotny and thus was not evaluated further. As a final comparison the effects of relax- ing the performance requirements were assessed. Since, in this system, motor size directly con- trols the acceleration torque available, two smaller and one larger variab le-d isplacement motor-pump were invt?stigated. The fuel economy results and the acceleration times associated with each performance criterion, along with the required time 'for ea'ch criterion, are shown in figure 7. The ,baseline system uses an hydraulic motor-pump with 81 on3/rev (4.49 in3/rev). As shown in this figure, the 0 to 30.5-m (lOO-ft) standst ill distance 'las met, and the 0 to 96.5 km/hr (60 mph) and 80.5 to 113 kru/hr (50 to 70 mph) required accele:ration rates were exceejed with the baseline system. Going to the extreme and decreasing the ~)tor-pump displacement by about 26 percent (60 cm3/rev, 3.7 in 3/rev) had little effect on the highway fuel economy and increased the urban fuel eC0nomy about 3 percent. The combined fuel economy improvement was then only about 1.6 percent. Again, these results are all based on a vehicle inertia weight of 1633 kg (3600 Ib). Adding in the small weight benefit eii,~ct oi the t>O-'cm3 Irev O.7-in 3/rev) unit \as- suming unit weight is proportional to displace- ment) increased this to only about ~.2 percent. This modest fuel economy gain was made at the expense of sub<;tanti,al increases in the acceler- ation times, from 18 to 52 percent longer than with the baseline unit. On the other hand. in- creasing motor-pump size to 100 an3/rev (6.1 in3/rev) vielded a relatively "hot" performing vehicle with a 0 to 96.5 km/hr (0 to 60 mph) time "f 9.1:> sec at a fuel economy penalty of 2.4 per- cent. Again accounting for the small weight penalty for the larger motor would increase the iuel <,conOlllV penalty to only about 3 percent. 127 When this relative insensitivity of fuel economy is considered, cost, packaging, and the aarket- ability of a ''hot'' performing vehicle may be IDOre significant factors in considering any trade-offs in motor-pump sizes with acceleration capability. The overall energy balances (including no- menclature) for the Federal urban and higbways drive cycles are shown in figure 8. Some of the significant effidencies for the system are as follows: Urban cycle Hydraulic drive efficiency 75.4 (C/D)a, percerlt Regenerative brmking efficiency 70.4 (AlB), percent Overall hydraulic system 84.4 efficiency (C/E), percent Overall engine mnd drive system 36.3 efficiency (C/F), percent aRefer to fig. 8 Highway cycle 84.1 74.3 85.1 36.6 The 36.3 percent overall engine and drive system efficiency is 45 percent better than that projec- ted as feasible (7) in the 1995 time period for an advanced diesel engine with a continuously variable transmission. The questioTI arises as to ho ... much of the 81 percent improvement in fuel econotny as compared with the projected conventional 1984 spark-igni- tion vehicle could be achieved by using a IIlOre conventional engine with the same type of energy- buffered hydraulic drive system used in this study. A detailE~d evaluation of this question was beyond the s(~pe of this effort. However, preliminary estinlates were made by simply ratio- ing the fuel economy results of the study on the basis of expected e~ine and hydraulic p~mp eff; ciencies. The results are presented in table I •. This approach ignores a number of specific dii- ierences such as auxiliary pO'h?r requirements, idling or engine--off losses, and weight diiferen- ces. However. these differences dre unlikelv to aff~ct the fOllowing conclusions for engines uti- lizing this energy-buffered hydraulic drive sys- tem: (1) the free-piston Stirling hydraulic engine and Jrive ,sys'telll offers fuel economy im- provements .i~nificantlv ~reater than would ~e achieved with either a dio?sel or spark-lgnlt l0n engine and (2) the kinematic Stirling engine of- fers a fuel economy improvement approaching that o~ the free-piston Stirl;ng engine. However, factors such as cost, complexity, life. and reli- ability, in addition to the fuel economy diHer- ential, ~ive the free-piston Stirling ~vdraulic ~ngine and drive system a substantlal advantage over the kinell13tic Stirling engine sV5t<'m. CONCLUSIONS AND CONCLUDING REMARKS The free-piston Stirling hydraulic o?ngine an' 60 :-- 25, 25, ~ => ,,: z :;: -FLU ECONOMy => => ::! ~ ~ a- u ~---O-~ ..... 0. SO~"'" ~ 20 r-' 2E =~ l DESIGN CRITERIA 0 ::J -. lOr-~ ~~ ii 0'" ~ 2! ~ fO TO 'Ib. 5 kl'lihr ii 160 mph, ACC[l£RAlION u 40'-:;: 15~ 0 ~ u IS L- Z 0 :;c "" ..... 10 r-..... u I ...J .. OTO'lO.5m ~ '100 It. STANDSTILL, ~ '"'" S~ '--==<> o :... ________ L__ __ L _____ ..L.. ______ J 40 60 ~ ~ ~ flYORAULIC MOTOR OISPlAC[AI{NT. cm~rw _. ___ .o.__------L 4 , HYDRAULIC MOTOR D:5PI.Ac[~,(NT, in 3, rev Fiqure 7. - Effeclol motor sin on combin~ tU4!t economy.oo perforlTlllOce. Inertia .. eiql1~ 163310] 11600 lb!. • 0 f:,1 '1,0'1'/' - E\l.>iM .EHICIfNO ~3'" - . Q.,::-;~ 1.12 T.'8 • ; tQ'.JrE' g . f rwrq, taalanCts ~or urtlan and tttQttMl\, ijriyt C'w(t~ "Jal11e$ 'S.h'CUn aff' ttMal inteqrat~ E"fl€Vg'f flOwi ~r UriV!' c-.'CK' In hON- ~E'r~~f(OOdS Tt'\oe first nuMber tn eaCM locahQflls tQr tht' urban ()'(It'. ft"Ierc cy. e H."n(y. comb lneO f:.Je 1 ent I ~ercent my improvement rt'sults are ,','fic."ntlv t'ncouraging that simplifying assump- t '<'''5 lIst>d in the studv 'hould not significantly .It~r the projt>ctt'd fuel savings. Alttloll~h ~~taiL~d ~vallJation has not been ·:1 •. h.i~.), prt:"timlnar~' t·stimates also indicate that :h~ tr p p-p'.t0n St'rling pn~ine should be signif- l ca!ltl~ ~etter thall more conVt~nt10nal alternative ··'1i.ine:o. '.sp~lri<. i~nl~ivn, Ji.esel, .lnd kiaemati.c :;t lriln~) >"l1th ~~h' 5ame tvpe 0t i\~draulic drive ..: "." ..;. t '.~:rn. S0 ~l'st pr0J~C~lvns were made in this study. -:-ht~ ~'v ·!"'.:l.Uil( ~ ... .,tt'n 3rr3n\letllt:~nt used Ln thls ~(uJv ~as :l,)t 0ptirr.iz~(i. Jth~r drrangements and \.""'t:lOinat1l)nS 1,.1! hydra":'~:,.: ('OmplJnents should be :!lVestL~ate(1 iurth~r. Fre""'-ri,st,'l!1 Stirll.n~ "~l~~ine to:"chnology 1'5 ~t L ~. 1:1 l~'; ~!1t·:lncv. Kl;1o:-'lTlat 1( St irl ing ,",n~in~c; \ : ...... :1'luJreJ ~10rS'-':J~'wt'r ~n .;;tz.t2 rl ... 1V~' ~t~pn ·.·~:!l;-:'.' ;)r\>~r,lm~ ... ,-'urr,~ntt:-: 1,~ve10pln.k'; ,)nt' t.'r ,i.l.:.t,~m .... 't 1\',' 1ppl i.(;.)t ilJn dt ~1bdtJt "10 KW' \80 hp). ~~,''ool,·\'t·r. t:11" t3r~t."'st :rt·~-pi.st~)n Stirlin)!, .-~ngin~ ~ll1 tt :., ,l,l'~.· 1,;;, .lbout 1 "ii' \ ... hp) . ..lOll the onl\" ':..!r.l\l~:~," j',ltPlit !rt.'le-pl.ston St irlln~ ~n~~u1t' :.:-- :. V"l,,'pment is ,1 ',,·.1rt ;)ump t'n~tnt~ Wl.::.h :·'·'I.;t -<-','; ~,J.!l~-hp) .)t!t;..n.:.t pvw~r. :'~1" _'[It l,:a~ r.'l~t·d.r .... rl ,1'1\.1 ..!t·\'t""~"-lpmt.:>tlt :1t:"t~~ :-- ::.l~ "·1~!i~t.~ JrlVt.' ";\'St"I~l ~!lt'n 1$ to J\:>51.~n~ ·'::~.d '1:~I..~ :t.,~t ,i ~f,·t.>-pl.;;t\)n :;tlril.n~, hydraullc 1,:\;;,' ~-: :''11.> 'I,'] t,l.' ... U ,,'1liii' , ... t) :~1 =).:.. hpJ 0utpUt -: i:':":,> ~:1 ,'r.!t'f :" ...!t'Vt' !,-,p .1:1\.1 ;,'.i L tJ.~itt' ~.hl~ t--"ch- ...;~" :;"; ~:lts ;'f,) ... ·\·:iS ",,\\I~""::1e:0 '::1.)I)~lu('~ ,,} '.i.:;ll::~lr': \-:1 .. :1.:1.' ,ltl.; r.tandatt:"l1 ~hat tnt:" t te~'t 1.11 _~\.)rn .... )blte:-; ~ulit :,~'f !~85 ;nust .lLhl.t.'ve ~1.7 ft..mt . : ": ..: -. - ~P&! \ .I.' ·:1~.ls:.Jrt.'"l :)\' ..!'/na.m ... 'm«.'tt'f ~t.·st$ ... '~~ .... ~ :-.>; :.'~\' '::tlVlr~;~m\·:l:.l.lo. :':".)t,"'('t.L:i\ 130 that conservatively would surpass that mandate by 84 percent. REFERENCES 1. N. H. Beachley and O. R. Otis, "A Study of AccUlllulator Passenger Cars Rased on the tfield Hydrostatic Pump/Motor Unit," Lawrence Liver·more Laboratory, University of Califor- nia, Livermore, CA, UCRL-15390, August 24, 1981. 2. Autor.otive Stirling Reference Engine Oesign Report. !iechanical Technology Inc., Latham, ~Y, !iTl-8l-ASE-640R-2, June 1981. (NASA CR- 1653111, 1981.) 3. M. H. White, "Conceptual Oesign and Cost Anaylsis of Hydraulic Output Unit for 15 kW Free-Piston Stirling Engine," University of Washington Joint Center for Graduate Study, Flow Industries Inc., Seattle, WA, ~ASA CR-165543, August 1982 • 4. W. M. Toscano, A. C. Harvev, and K. Lee, "Oesign or Hydraulic Output Stirling Engines," Foster-Miller Inc., Waltham, MA, NASA Contract NAS3-22230. 5. W. O. Rifkin, "Free-Piston Stirling Engine Accumulator, Buffered Hydrostatic Vehicle Drive, Final Report ," Ener,~y Res ;arch and G~neratirn, Inc •• Ua~land, CA, ~ASA Contract ~A.';j-.?1-'+d3, 1979. '>. ~1. 'tagi, A. Freivald. i. Andersson, and I.!. Ericksson. "On Vari.able Hydrostat i.e Transmi s- S10n for ~oad Vehicles, Powered by Supply of Fluid at Constant Pressure," Volvo Flygmotor A.B., Trollh<'etten, Sweden, Rept. 301-7063, ~lav 1981. (~ASA CR-!1)5246, 1981.) f. C. 1... Gray, Jr., and F. von Hippel, "The Fuel Economv _'1 Light Vehicles," Scient die Amer-' lcan, Vol. 2-'+4, No.5, May 1981, pp. 48-59. ". D. Sabath, "Aer<)dvnamics to Dominate Ford's Future," Cleveland Plain Oealer, Au~usr I ... 1982, p. 1:-0. " ',;. F. Marshall and K. R. Stamper, "~:ngine ?t."'rt~)n!1.ance Test ox' the 1475 Chrysler-Nissan 'lodel CSI)3} Dit'sel ~:ngine," DOD-TSC-t),;T- 75-44, Septt>mbt'r 1915. \1). "Pertormdnce Characteristics of Automotive inl{in~s in the L~.S .. ,It En~rgy Research ,10J )eyelopment Administration, Bartlesville, l)K. Department of Ener~y, Bart lesvi lit> ,:nergy Te chno lo~v Center, Sa rt I"sv i lie, llK • :{,'pt .... - :-hiru St!rl ... ..;. ~f.R(.·O?--~ diS. A simple "nal'lsis was made or. a new Stirling engine design 20ncept. The concept makes use of an insulating ceramic liner in a 2001ed metal structure .0 form cvlinders and regenerator hous- ings. [he concept is intended to reduce greatly the n~ed for eKpensive. strategic, high-tempera- tllrt~ ,111U"';S ..lno :0 improv~ ~if i..:: len ... :::. i,;e .:10.1.- lysis report~d ht?rein rt.·vt.~aleJ that 5i.~niti..;ant eiticien~y improvement is possible it ::/linc..1er inner-wall temperatures can boe incr('ased .1nd made more undorm along the cvlind('r length. Pott'n- : tal etfi.: ieocy ~alns .:is hi~h as ::0 pt'r=~·nt tL'r a ':'C-kW, lnOO-rprr <,m;ine were calculated. TI", rc'- sul:s Jt this ,lnai~'sist whictl did not 3adr~ss ;)otc·"t;,ll practicaf. prc)bll'ms r('latf'd to the lISC' ,.)1 ':t.>r1r.li.: lin~rs, :-iu4~eSt that this .::.")n.;;:ept d~"-· s"rveS 1 ri~Jrous [h('r~al and d('sigl1 analvsi. [J jefint.· tts ?ott"'ntlal benetits and limitativns. i ---1 :'HE .';::~~:.tSC "~~GlSl~ !"equlr~'S t"r"13t ::.-;.,: It:' 'it'at aJ- .1it1..,'n ""''l' ~rl~U~!1t !:o the \'''\.lrKin~ :"luitl :,'/ tr.Jn:;'- t~r 3~r0SS lJ3d-~~,lrlng ~0llndarl~s Jnd ~nat th~ ~l0t ~nos 0[ :he ;ylin~~r 3n~ re~~tl~rat0~ ~l0t!S1ng~ :)'l.~ ~~·Pt .It to;~mpt."'ratul eS .: l.. .. )S~ to tht:.~ ;.tax Im\lni w')rKin~ tluiJ tt..~mp~!raturt:'s tl..l .Jvoi\.l ~na':':<2'pt.1!:>1~> ht..~<1t 1 ~'~Se~.. -;'"h 1$ means ~hat t ht?' ;-:'lax imum ..: vc it'> :~mpt.'ratur€ .1nl.i .. nl~ll,,:e ... I:."ii).~l~n..::::.· ar~~ Itr.litt2'J :' ..... ~~1t~ :1i.~h :t"lmpr'r it:.lft:.:" .:n:'t.?~) rupturt' ..;,tn·n.~th vt tnt..~ o;·a~.l:it:.' hot 't"n",1 mat~r131::> ___ '~ ':"10:;[[,,,,":- ttJn .. ~t l~ ~t-"ln~ral practi.:t:> fl.)[ Stlrlin~ j1;'- si~ners ~0 t.·mpi0Y .:ostly .. high al1o .... m~tals f .. ll" :lh'St> _','(~pl....,t 'nts .. Su..:h 311o~:".: as S-l)) a.nl.l ;'{S-.;l art."" t·"Pl";3i. Tht! ~9ncept vi a ,;,)ol~d, lnsulated ~n~ine was SU~K~sted bv Meij~r and ~iph in [h~lr ~tuuv ,",~ :.h!:.~ Stlrli.n.g _'n~in~ !0f l-tc-3vv-dutv ..1p- ?ll..:att...'tls \1: .. * The-v propos~d ~lass-('.·raml': --·--~ .... 'rl<---i\?'[L.)r.:I~~u for tht> l' .. S .. D~~part~nt 1."': C:1"'r~\" _:hh'r :nti'ragen.:v ,~roet·mt:.'nt JE-AIOl- ~ 7'("S 5 1 ~)_I) ... :':~U13bt.~r$ in ?.1r.:onth~·-;~$ ,J~si~nat~ f~t't~r~n :-cs ,It t':h.l ,,'! p..lp~r .. 131 A L.ook at a Cooled, Insulated Stirling Engine William A. T omazic National Aeronautics and Space Administration Lewis Research Center CleV2land, OH lnsulation material enclJs~j in cooled (,Kt('rnal metal sheaths for the .. n.pne c y I tnders and regen- erator housi~s" Since the metal load-bearing strocture would be at low temperature, ~ostl~' .. 1- lays would not be required. The glass ~('ramlC insulation would greatlv restri~t the radial heat ~onducti.on out "f the ~vlinder and regenerator housings. ~eij('r and Ziph proposea that the ra- Jial heat ll..l~s · ... ·\."'ldd ~t· ,)i the same :)rd~r "f -;a.!- nitude .15 the .l;o~i.al heat :"1.1tll.luctl ___ "m !r"1m the ;.....~·t end dovn !:o the,:: ....,ld end .)f a .: L)nVent iona 1 a 11- metal Stirltn~ ,'ngine aile that th ... >liiciencv l~v~ls would be equival~nt. Th~v assumed a :ner- mal ':l"nductivlty ~)f O .. ~ .... , -:c for th~ ~las::; ~r!ra- tnl"':. 7'his valu!!:.'t l .... )w~r than that f ___ 1T ~·.:'Hnrrlt~r- ':lall:1 availaole ,;lass '::t:>raml( mat~Tlats. :....; ! ... ~r a proprietary mat('ri21 ctev:loppJ ,y ?hillps ~r- search ~ab"ratvry. rh'l.~ .: ... 'tlCt?pt ,,': ·.~Slnk!, ~1,Js5 ":t~r3mi.: insulatIon in this ~.annt"r was int!"l:"Jll ... ~ .. >u ~-lS part vi tht.. .... ..1Jvanc~d St""r~in~ en~lnt~ t~ciUh~~ llgy wor~ done at Philips Re~ear~h .~ab0ratory. :t ~a::> L'In!"~- ...:r3rn :Jt.::'\.~r\. tih' ..:- .'n..::ept ': ___ 1uld ')t~ ...:.t"v~l\"'ped. ~·he ::1..,\\.llcu l.ns~.l.lt-:"l1 St I rlln~ '·01~J.nt:' 1 i. ) :,...r~ :-: .. "'It ___ "'01 .... tht" pvtY:"nclal ... ): r~du~l.n~ :~"'st. JI.;t 315~ :nc PI..."'l:iS1Dllltv v! unprl..)v\n~ ~.: 1': li'O":y 1: r.hl13! :,)nducti0n losst"s .::\.)uld b~ !,,1;:~dW:t.."d witn ':hJri" 'l~::i':lt!."nt insui.atil)n .. A slmple. pr~li.:Ulndr\: "'tu(:"\" ... ·as ·J'!1JcrLli<.~~n at :"t"'Vl~ Rt':-:'~,Jr:h l.·~ntt"r ..:.,'c.p.ar~ :1eat ·: .. 1sses :~)r ~:1~ ":\.h~it'''':'. :;l.:-'l~:"lt,-..; ..:. ..... ncept \l1th thos~ !I. ... r ·~'nvent10n.al t'rh!l:'l~S. :-h~ t'tti"<.:ts ,,"li t:'nS'!ln~ power :t"vel .1111..] -':~''''14n sP('t."! ~er~ ~xamin~d.. The results l",[ tnl~ 3ndi~sls Jr~ rr~sent~d herein. ~~~ l~t~nt 0i thiS dnal~sls lS to ~0mpar~ ht.~at !I.JSS~S !OT" a ":Llolt·-.}. :..n::;ul.ltt?.! -:'~~lnt.> With tn\."'st:" :'.)r a .:onvt"nt 10n.11 t."n~i.ne :;och ..1$ ~~'t!' ['nlt"d St lrl1ng P-... O. ,'YLI!'IDER ~!OOEL COI'iVt;;.!\"TlONAL DIG1NE - ~'l~- ...Ire ~ shows .1 s.:nt"m.3.t1': ,::rI..1SS St~:tL0n ___ '[ ~l ,~ CYLINOE R , ~ PISTON -, Tl _I f"lure 1. - C:J(wenh'l<\.3l fflJtne cvlinder. 132 cylinder for a typical conventional Stirling engine. Heat input to the cylind.~r is through heater tubes at the top of the cylinder. The outside of the cylinder is generally insulated. The bottom of the cylinder is fastened to the cold end of the €·ngine. Conductive heat flow is primari ly downward to the cooled lower end of the engine. For this ancllysis it was assumed that all conduction was downward, that none was radial, and that Tl' T2, T) were cor.stant across the cylinder wall thickness and constant for any engine size (liT/I. would then decrease with increasing engin., size). Four types of hoth pn'port i,mal tc ;)i' Thus, , ll~ (' «;_1- ~s C ?Ul~l:-~SS - This lL)~S l)'j .ls.;rih~d :.J Cit? m0tion of working gas in and 0U[ 0i the radLai ~ learaIlCt" volume betwt"E'n t.h~ P1Stvl1 .]nJ ~~h:" :. \' l- inder' .. It ':;.3l~l be desc[i_t-ed USln~ 3 -rl~Lath)nshlp 01 thi! general form proposed :,y Rios ~:) ane. ~tarti"i (): It is assumed i.n this ana!.ys1s that al: pr('ssur" and temper'ature relationships in tillS equatio" remain ~onstant as engine siLe lS varied; t hert"ioT"i!, where v g S c L. Q • V gp g and where clearance. [ is the length and 1ince Lg ~ 0i' Q O~C gp ~ l C lS the Note that shuttle loss Qgs is directly propor- t ional to : learance, while pumping loss QgP. is inversely proportional. Their sum is at a m1n- imum when the two losses are about equal. The : learance at which this occurs is generally im- practicallv small. At practical clearances, Qgp will be subs.tantiallv greater than Q s. This analysis ass.umes that c le'lrance will ge kept con- ,;tant at the minimum practic,ll value for all sizes of engines ~xamined. The reg;enerator housing is als0 subject to ::.onduction losses ~!1 the same manner as the :ylinder, and the same sort of equation applies. It is assumed that the regenerator is also scaled in direct proportion to the cylinder and, therefore, that the :onduction loss Qcr in the regenerator IS proportional to engine size in the same mann .. r as cvlinder conduction loss. o • D. ',: r 1 Engine pow,'r R is proportional to displaced volume and engine 5DPed if pressure, temperature, .111<1 the ,'tht:'r ,it-::,sl~n parar.lt~tt::~rs (hat affect p)w~r ,1rt:' "t:~pt .: .. )nstant. irrespl:"C~:'Ve oi engine power I~vel L'r d~sl~n sp~~d. l~00!..ED. ;~SL'LAn:D !C:-iGI:-iE (,Y!..!"IDER ~ODEL - A s..:h~nl.dti...:: ..:r0S5 'S~...::ti ... )(l 1i 3. .::ylindf::'r for a _';.),,--"'l~u\ t:lstda:.·.j s~ ~rl i~-:.~ ~n~inf? is shown in ~ l~drl~.2~ 7ht? t'nginc' '--~!"'!Dl,-)::s a .:oolec out~r metal ~~ll~J~r 3nc r0g~n~rdt0r housin~ lined ~itil 1 10W-~011du~tlv~tV. ~igh-t~mperat~re glass ':cI",lr.li..::. ' .. :ni..:n "..;i.:i l;!$ulatc the metal structure [~ pr~v~nt 0v~rtemperattJre and 3i~o minimize con- "u~tIV<' heat L'5S. ~he analysis held the tollow- l:h~ .1';;;Slwlpti ... "'In:;: .~'t' ':~"':~~!"."::':\,l~\" ,': :~·Io:.~ .::.1.3s:5 :t:'r~~mi..:: liner ~dS 1).00b ~,=~"(. "lllJ :ne :n12~ness t0r all .... :"t,gin~ ..::onfigu:-att,lI1S was l.:w. The inner sur- face of th., lletal structural wall W;IS kept at lOO~ C for ali L~~int.--' :onfigurations by water .:oolin~. !'urther, :tIl :onJuction was radially "utward oy.:r the wh"l,' :':linder surface, and no ~:()nduc t ion .... "":..: urr,"~l1 J~"l .... nward ~ Cvlinder Radial C,)nr-.: ''Xs a~ "IX!!"" .. '01- )d!) 1~"JO''' turf- dtf1E'ri'''fI.a1 131 ~---. where 'W ," taken to De equivalent to Thg' For ditferent engine sizes, t) = (~~~)2 [57.2(584 _ Tw) + 225];'; o(p Dp_40 Clearance 1S again assumed ,:.onstant. T"tal H€'.~t L"ss - The specific .:quation used :" ~ al~uiate -total heat l"ss tor various .. ngin .. '" 1 zeS .. ~ + {) ) 'gp '': • ~.:5]W [ ".1:' I,' - 100' ',:) '" :,)t.ll nt"at-:~.,ss estunate"s :0r ":JOled. i.nsulateJ ":1>( l:1':S .'! ~\l. dO. 160, anJ l.:0 ;"1.1 nominal power 1
raLlre t\.lr ..,~.'v ·-r,). .'n~l:)t> J-,~Sl.~n p0WIt·:·r :.~v\:~is. As :l1iY.,ht ~.' -:"[)",.::~'-. :--p,,:· .. :~:"l.": ~'It~at : ,:;s "!'l·-:rt.~3$'l~J i"ll.:h :':1- -: !""t:',l:-:.~n~ '..,',11: ~t·mpt:>r.....ttllre. :-~ll:; 1:; L1e to (h~ :r";h,n,~~~:-_lnt .!.! .. ).,':: \..': .1earc.lIlC€' l,)ss~s. In ?.Jr- :~..: ~L,ir·. :r~.- ;"\IMPl:1~ : ... )ss. ~p~lii..: tlt!at ~"":'S .. ·d:' l;'~,' :- • .:'..!'..:"::t·~1 .is ;:It..)w~r · .. .3.5 In...;r~''~l$t)tl. LI.'Sse",; .·-r~· :-e:..lt·:u ::,-' .. )ti\"~t lVt.~ :;ur!"aCe .ir~.) ,ll1\l :.n- _r ... ..1::;.·u '.)'.' ~nt.' ::;qll.3.r~ ,)t tht> ,:·:ll.H:ier dlamt:"tt'!". "'~11 :~. >' ....... ; '.1,10.; ,I ::In..:tl.,'n ,. :l .... ?la .. ~~.,.!!·h·,.:1t 1:-:......:. :'h' ~'':.l:1t:-' rt'pt:"t."$t"n.~ln~ :l.'tal heat i ... ")ss'l·s :~lr :,"~lvt"nt::'I.Hlal ~n~!.n\!"$. i::ttt"'CtA.ve ')Vt.'"r3~e wall :~~mp€'r,"ltur~' \or."1.5 .1:;s.,Jmt-d ::1.) O~ ... 40;' ..... :l'r .iii ?v~r It!'v~ls. l~ a lln~ 1S ?rl)J~.:t~(} ill.)rl.!0n- :all~ :0 :~~ ~0rrespondin2 ~Jol~d-~n~ln~ !1~dt :05$ : }.:h .. ~. :-:h~ ... a1 I .::~~mp~~r-ltul·e _it .... nl.:h ';\)01~ .Irt.'" t."'qual !:\.) ··"Ir"!.·!':..·n~i011aL t""nglnt~ l .... '$ses .i.~ jt"1 ln~a" 1 ..:ai i !.:U.s tht'" "':>r .. ~a.i<. .:v .. ~nlt t~mperatur.:- .. Above thlS tt..·mpt·ratur~ ...:,,)\..)li>d ~n.;; tne ;>ertt,}rflan...:t! :-inl.)U l .. l ~X.(;~"~..1 ..: L111ven" }.\..)n..1 t "_'n,glne perfort!laoc~·. B~l ... )w. ':,}olt?J t"'n~ln~ p~r- !0nbdnc~ Will :>~ ~ ... )\(te'r. Fl~UI·t."~.; .Jnd .... -:,how th~' 138 same info~tion for 2000 and 1000 rpm, respec- tively. 'l1le trends are essentially the same at all s~eds, but the trend lines are steeper with lower design speeds. Inter('stingly, the break- ~v('n t .. mperature tends to be higher with both higher po", .. rs and lower speeds. This can be seen clearly in figure 7 where br .. ak-even temperatur .. is plotted as a funct ion of design power for 1000, ~00f1, and :'000 rpm dt!sign .. peeds. For t!ach spe .. d, the break-ev~n t .. mperatur .. incr .. ases with nominal p"wer and app .. ars to lev .. 1 off at powers above about 300 kll. The l .. vel of break-even t""'p .. rature iloeS Lip as des ibn speed is r .. duc .. d. Th .. potential effici .. ncy ben('i,t of the cool.,d, insulat .. d pngine conc .. pt can be s .... n more dir .. ctlv in fiilure 8. Here is plott .. d the speci- fic h .. at lo~s differ .. nce betw .. en uncoolpd and cooled pngin ... dS a function of avercge wall tem- p.,rature for a ran~ .. of ~ngine power and a d .. siiln sp .... d "f ,'.000 rpm. Specific h .. at 1055 difference i~ defin .. d as to'al h .. at loss for th .. conv"n- tional eL~in .. m, JS total h .. at loss for the cool .. d, insulated .. ngine divided hv design power • This quantity is also numerically equal to th .. relativ .. increase (or d .. cr .. as .. > in th .. rmal effi- c,encv. For .. xampl ... a spec ific heat [o~s differ .. nc .. "f 0.1 denot .. s a on .. -tenth, or 10 per- cent. increas .. in th .. rmal .. ffici .. n.::v (such as )?,oing from )0 to 33 perc .. nt). The break "v .. n t~mp~raturp can ~e s~~n cl~arlv in thl~ fi~ur~ .1 ~ th(~ pOlnt at \Jhich .:>ach 1055 1 in~ ~r0")Ses th~' 7erO line. The maximum gain is i",r a ... O-kW ~ngin .. with an .. ifectiv .. av .. rage wall t .. mp .. rature approaching the averag .. expansion t .. mperature. This gain is progressive Iv less as .. ngin .. pow .. r is incr .. as .. d. A 1~O-kW engine gains onlv about 1 percent at the 5ame temperature. This' ef feet is due to .. ngin .. powel' increasing mol''' rapidly with engin .. siz .. than cvlinder and regen .. rator surface area. Since the losses are relat .. d to ~vlinder and r~g~n~rdtor surface dr~at th~v ne- come- a less signlficant fractio:1 \."It t)utput power .1:-; S"lZ_' incrt;oas~s. rh~rpf,Jrt). any ~~chniQue which tt'nds [0 r\)~uc~ "';l:r:ac~-area r~1ated 1osse~ ~as :~~S. ~itpct ,)n ~~'rtt)rman~~ as ~n~inp power IS I nc r~).lstld. :~iRurt"::: 9 .1nd 10 :=::h·, ........ th~ ..;.at'l-e r~lat l()nship:; !0r ~n~ln~ desiRn ~O~~dS 'i ~000 :-pm and iOOO rpm. rt-sp,""ctivt..>ly .. nl,) ~a.m~ ::rt"'nds 3rt::> ,)bst"rv~d .. How~v~rt th~ slopes tncr~as~ wlth lncr~aslnR de- .i~n ~pe .. d. Thp maximum pOlsible gains are ap- ?r.\xlmat~lv I", p~n>~nt J.t ... 0 !<.J,i ~lnd :000 rpm ~lnc! :'i] ;h.:>r..;~:>nt ,it ... 1) ;":'", .1nd i:JOlJ rpm. Ih15 • .l~ain, r~il~cts the ~ti~ct 0i ~urtac~'arpa Whl~h lO- ~reases with increasin~ d~si~n ip~~d. (ONCL~DINC ~~~ARKS ~'ht~ .:\.")n(:~pc .'! !l.5tn~ ln~ulat~'ti~ t001i>d cvl- lnd~rs drid r~Ren~rat0r ~0U$l.n~S :Of J Stlrlln~ ·'ngl.ne oif~rs th~ possibilitil ~'t ~arli!(>'lv t:"'limi- ~ating the ne~d fJr expensiv ... strat~~I~ high- :O>l!lp .. ratur .. allovs. This lS "bviouslv J;>Str'- .lble. :11", qu .. st ,nn '.'t wheth .. r 3nd .md .. r what c ircumstance~ th,~ l;>pr"a<-h to St lrltn)O! ,>n)(in<' < '3 .G r- r-- J AVE\TIOr-.Al l'.GI~l ..rAT JS~ ., ..... - " .. .,:. 139 "'f .. • J. ~ .... (, :,.\ l ~ ~::.,';::.:.! .~ N.r .TI(I"~, ·• .... r" :.t-~ 't . ") ~ ".' i' .. ' ' .. ".IA\f :::: 'i x. '" Z :: 5:' ;;: .r . --- - --~-----~.--~-~- ------"--------~'-- !<;O lIS SOO S25 ,<;0 SIS 000 ~"£RA(1 ,'IAll TfMPfRAIURl. T ". lC ; "lure i Spec,liC heallo<~ 1ilference oet-..een COOled anO '""'~rh,)Oal enQlnes. ~~Ion ~ 4(0) rom. ENGlP.{ ~£SIGh POI/[R IW 40 rp -oj "\~ 1~1( "t;'dt ,''X~ ~,f1e-r~l"(t" ~t""'~n ":")i)'e~ and em· .,!,r'I!I,'f'al ~"\)l"~" J"?,,-.;"f'\ '~fll ~'(() r:'lr" .\q"J. ::.~ )1> .• \ ~7S '00 'l" ""'-1 v< ~.·!RA(1 .~illl ;:',ljX\l.\TlIU ' •. :- ;!Qur~.C )tJP(lh( "ltt-.at 1I.x~ j.'~f'~rl(o "'t'lte'f' :~t·: .:I''''' ,.,.,.t'f'toOf'-41 '''~r:ts. )f.\Iqf1 ~t1 .))) '~.~ 14)0 design could result in increased performance was examined in this simple analysis. This analysis does not attempt to address the practical prob- lems which may be involved in the cooled, insu- lated engine concept. For example, the design of a small engine (of the order of 40 kW) may be severely compromised by inclusion of liners thick ~nough to do any good. And, no consideration whatsoever is &iven to the problems involved in installing and ma,intaining a glass ceramic liner in a practical engine of any size. The results of this analysis indicate that performance gains can be made if appendix gap losses can be reduced. It appears that this can be done if higher cylinder inner wall tempera- tures can be achieved. Oddly enough, for the as- sumptions made in this analysis regarding the r~lative values of conduction and appendix gap losses (which are based on P-40 engine calcula- tions made with the Lewis Stirling performance code) overall heat losses actually decrease as radial conduction losses increase with higher inner wall surface temperatures. The appendix ~ap losses dominate and are reduced substantially 3S wall temperature approaches the expansion t t~mperature. An engine with an active COOling system and appropriate insulation should provide the oppor- t'mitv !nr control l)f the cylinder inner-wall :·'r.1pc;"r,:lturf·~ Speciz·i .... -.:llr ... ~"",. this w,)uld Ot:' dl)nt~ tnd · .... hat tt-'>mp~'ratlJrt>' (dn engine design power engine pressure ratio engine stroke uncooled cylinder reference tPmperature, top uncooled cylinder referpnce temperature, middl .. uncooled cvlind .. r reference temperature, bottom average expansion tpmperature hot .-:ap ternl rature ..:-:1 inder inllt:'r 'ooiall t,·mpt"'r.lt ;r~ '",all thickness displaced volume annul _ ..... ~; -;'.J'«>~ -:' ''!. :iG~"" .-~ .... '" ~'i!'C ;3' 1'0 ::'111!':;~"""''fl,.... _~. :. ... ~I~, - .. 4"'\ :i'C\I!I"'.l ~ .. ·~.::;,~o?s ... ~"'. i"', ."--eo' ~:.r-··l:~S ~ ....... ~. )..,'~':-'c:. JI~~E"-' t",....C' .... ',~') ..... a .. l:' ... .Ii"', "d'- .it''' .. t;>":-',,0,:;:-t .t"'it'Ol"~C> ,r. ':w .... -eo i .. -C .. " ole. = .:""""~~E'S'S Y .. se' .. "'t"$50 :" .Jf". ....y..,.,,j!'C" ~'Cd·I· .... S :'x .... .:· :- . .)"Xo:l''\f\ ! '>.:' c~'" ~ ... t"e-~""''''' ""elt ~, _.,.(?o .: _ .~ ~~ .... ~ '41 GAS TURBINE TECt~iNOLOGY SESSION Advanced Gas Turbine Technology Development (Systems and Components) ~A(;T The Garrett/Ford AGTIOI Program has pro- gressed through initial design, fabric.3tion, first gen- eration aerodynarnic component tests, and currently is focused on engine test bed development and ceramic component development. \1any significant development act,ivities have ~een accomplished, including successful full-speed operation of the AGTlOI \1od I (I 600°F) engine to 11)0,000 rpm. , A complete sey'oIcei·a:miC statk structures, consisting of 49 parts, was assembled and success- fully tested in the structures rig to the \1od I (t 600"F) design conditions., \1any ceramic structures have passed thermal screening tests to 21 OO"F. .'\ silicon nitride rotor, produced cooperatively by ACC and Ford, has been spin tested at room temperature to 1 Q2,000 rpm, whkh evceeds the 'naximum power design condition. Aerothermodynamic component testing of the first iteration AGTIOI (2500"Fl turbine design has been completed. Results of these tests show that final program goals have been exceeded in the low- power regime and initial goals ~ave been exceeded at maximum power. The second compressor test "as been completed with results showing that design flow and pressure ratio goals have been achieved. Com- bustion fuel nozzle development indicates that pro- gram emission goals are achievable within the ;>ro- ) gram time fra'ne. ---' efforts indicate that \G Tt ') I program goals are achiev Ie. ()ver 37()O com\)Ol1ent rig test hours and over 90 r;s and I g5 starts '~ the engine have been accumula in the developll'lent test progra'n. Testmg contil)lles. ith empha~s ,:H'I perfor,nance. inco.-poratio?" of cera ic cOll'lponents. and higher temperatuy capability. I:'IJTRODUCnO\l \0 automotive \dvanced Gas Turbine (\GT) technology progrJ\tn is 'x'ing conducted !>y Garrett Turbine Engine C.)cnp.am ;me! Ford \Iotor Company 145 R. A. Rackley I!I1d D. M. Kreiner Garrett Turbine Engine Co. under OOE/:'-IASA Contract DEN3-167. This effort is a significant p.:I.rt of the Gas Turbine Highway Vehicle System Progrilm esta':>lished by the Department of Energy, with NASA-Lewis Research Center providing project management and administration. The Garrett/ Ford AGT (designated AGTIOIl is a 100-horsepower. regenerated, single-shaft gas turbine engine. Cer- aenics are used extensively in the engine f,ot flow path. The status and technical progress through September 1932, which completes the third year vI the project, is presented in this document. TIle project was initiated October I. 1979; t~le original program schedule is shown in Figure t. The Figure 1. ~GTlI)I Original Program Schedule. qefereoce Powertrain J)esign (RPf)) preli'ninary design review · .. ·as successfully completed on January 10, I Q80 and a second design review involv- ing the \\0<1 i powertrain and initial development engines was cO'npleted on \pril '\0. 19S0. Plese two reviews were held on schedule and successfullv <':0'0- pleted Contract \tilestone t. There have !leen no significant changes 'to the initial design since incep- tion. ' The Garll'ett/Ford pt'oject \\/orl< p.lan W.'lS -nodi- fied in FY 1931 to accommodate budget constraints. Testing of several first-generation -neta:lic compo- nems was reduced. power train <1evelopment (gearbox and transmission) was deferred, and vehicle activity terminated. These changes permitted concentration of resources toward continued development of higher technology components and ceramics necessary for the .-\GTlOI engine. 'iignificant progress was made in FY 198 I as aerothermodynamic testing of the \~od I (!600"F) components was completed and the first engine was assembled and tested on July '31. 1981. '\s FY 1 '~82 approached. the fiscal restraints caused restructuring of the :\GTII)I program ,~s shown in Figure 2. .\dvancement of ceramic tech- nolo~y. irnproved co'nponent aerodynamic perfor- 'nance. and POWN section development as a "test bed r---========~:_=:u=_==:~==_=_:~= __ =~=~:~ ___ ~ u,~~ -81 .-~---~-- CUlISI( B£'JIlOPMUH SfRUCTi.tItfS celtnUSTOil 'uRllt1! R[6!1.UATIlIT OIVILOI'IiUT COll'Oftl.T \Jf"&RAM 'OVlIR SltTIGII II£YIlIli'MlftT 8P1l,-uUAIft 1f'WttePil£.T I .~~!.~)n!.t$SfSS.ftlT Of PRODutt8ilITl ~.lIOO J STAuCTUIl(S ::=~: l U:t "A."lJ~ltTURl!.& lH:'t'tlOPVf"_' _____________________ . Figure 2. Restructured \G T II) I Program. for ceramics" were considered key objectives of this program. The power section performance objectives .:If ').3 specific fuel ,:onsurnption (sfc). 100 shp and low e'nissions were 110t changed from the original program. Wilen these objectives are demonstrated. ;>rivat~ :ndustry will fund powert~ain de"€'loprnent. -\GTI')[ DESIG"l FE..\TURES - The -\GTI I) I engine. as s~lown in Figure 3, is flat rated at 11)0 horsepower. with d 'nmimum sfc of less than ').3. The single-Shaft rotating group is co'nposed ,)f a turbine. compressor. and output gear supported bv .lr1 :lir-Iubrtcated. fOil-journal :,earing and an oil- lubricdted ball :,earing. .-\mbient air enters the ~ngine through variable inlet guide vanes and passes through a single-stage compressQr. The compressed air, at approl(imately 365"F. is routed around the full '-'ngine ;>er imeter to the 'ligh pressur€' ,ide of the ceramic rotJ,ry regenerator. This feature provides increased thermal efficiency by minimizing heat loss. The partially hedted air r)sses through the regener- ator core. where it is further heated to about 1940"F 'naximum temperature at idle. and then to the com- !xistor. The ori.ginal combustor design utilized variable geometry to limit primary zone maximum tempera- tUrt~S to 3000"F to suppress :--lOx fonnation. provide a prevaporizing/premixing zone to limit particulates and unburned hydrocarbons. and provide a high level of mixing along with minimal wall quenching to dssure low CO fonnation. Recent :--IASA and Garrett work indicates that a less complex design utilizing a lean-burn, low-ernis- Figure 3. AGTll)l Power Section. "ion. fixed-geometry combustion system has high potential of :neeting the ernission require-nents. Hot gas exits the combustor at a 'naxirnum temperature of 2500"F to the turbine stator and then expands through the radial turbine rotor. The turbine exhausts the hot gas, at a maximum temperature of 20300F at idle, to the low pressure side of the rotating regenerator and out the engine exhaust at d 'naximurn temperature of 5ll)"F at maximum power. .-\11 ceramic hot section structural components are symmetrical except for one housing that separ- ates high and low pressure regenerator flow. The symmetrical design provides a more uniform stress distribution and ease of manUfacturing. Key ~ngine components have been undergoing performance testing in rigs during FY 1982. These activities are summarized in the following para- graphs. C()\1PRESSOR - Two additional corn pressor rig tEOsts have been completed; Tests? and 2..1,. In Test 2, the modified impeller (increased tip and shroud recontourl was tested with a valleless diffuser to establish impeller characteristics. Results indicated that, as desired, flow and work increased over Test 1. In Test 2A, a three-stage diffuser, designed to ma.tch the modified impeller, was installed and full stage testing was completed at speeds fro'n flO to 1')0 pet'cent of design corrected speed and IGV settings of 0, ~20 •• 40. and .70 degrees. Axial clearance through- out the test was controlled to within 1).001 to 0.004 inch. Test results, comparing the original design (Test I) with Test 2A. are shown in Figures 110, 5, and 6. This data indicates the following: () r}t;~sign pressure ratio and flow were attained o Low speed efficiency was significantly increased from l'est I o -\ desirable efficiency envelope has been --- TEST 1 5.f1t11 - TEST 211 !15 100, , 95-, '. 8fj " , 4.l1li 3.5IlI 3.00 90-, ' 2.50 ~\ Z.DII -- ,',- ~ 50 .--,~. IIIJ 1.50 50-~\ ~,\~€O 110 l.oo'---~-~-";:;::-~-~' 0.10 IlllI D.5Il 0.10 0.96 RATIIfIG STATtIJlI lftLET CORRECTED FLOW. LBM/SEC Figure 4. Full Stage Compressor ,)ata, IGVs Open. ... c ... "" ... 0 ... -~ "" ... <::> ... .: ... '"" ... i3 ~ .... ... 0110 0.75 O.1tl 0.65 0.00 ---TEST' 0.55 -TEST 1.11 3.00 3.00 2M '.00 ~~~, ": 1.50 --.... ',,", \, 10 100 ~-~,~ 0.10 0.20 Ol) 0.40 o..'j6 0.00 0.10 om RATiil!G STATION UIlH CfliU1ECTEIl FlQlll. lBl!1I/SEC Figure 5. Full ')tage Compressor ~at3. IGV = 40 ')egrees. achieved, which has the peak efficiencies increasing at the lowef" end of the spt'"ed range where "TIOS't driving time oedo ... o ... .:. c ... C> ... .: ... II< ... ~ .... ... .... "" ... c:> ... o ... .:. c ... ... ... s! ... ... IE: ... '"" :> co 00 ... "" ... 0.80 0.15 (- 0.18 " 0.&5 0.80 0.55 um ----TEST I VIO -TEIT2A D.45 BIITIIG STATIOI IIiLET CORRECTED flOW. LIM/SEC Figure 6. Full Stage Compressor ')ata, IG V = 70 Degrees. TIle Test 2 -\ map has been input into the \\od II cycle analysis and currently is being evaluatetl . TURBI:'-IE -Cold air testing of the -\,.";nOI ceramic desi!:n turbine stage has been completed. \\etallic comporations we~e repeated prior to test initiation. Test results, as shown in Figure 7, .ndicate [he following: Figure 7. ·\Gn 0 I Turbine Cold Rig Test (I "82), o Initial design goals were exceeded at idle, cruise, clOd maximum power conditons o Program goals were exceeded at idle and cruise power points o Exhaust diffuser performance remained extremely good over the operating range An 84 percent idle efficiency was achieved compared with the 79 percent program goal. Cruise performance was 84.5 percent versus 84.3 percent predicted. .'\t maximum power, an initial design efficiency goal of 8;.7 percent was projected; test results show that 85.2 percent was achieved. Table 1 presents a summary of the AGTIOI turbine develop- ment testing conducted to date. Table I. AGTIOI Turbine Development Test Summary Initial In::ial Program Goal Test Goals r-------- Idle 1600°F 0.718 0.763 -- Idle 25000F ').762 0.840 0.790 Cruise 1600"F 0.782 0.796 --- Cruise 2500"F 0.815 0.845 0.843 \iaximum Power I 600°F 0.871 ').865 -- \1aximum Power 2500·F 0.837 0.852 0.865 In an effort to assess tested turbine perfor- mance on powertrain operation. the tested turbine map is currently is being input to the cycle analyses program. Fabric.:l.tion of the dual alloy turbine rotor for operation at a turbine inlet temperature (TIT) of 21000F has continued. The rotor is comprised of a cast \1AR-\\ 247 blade ring with direCtion"lly solidi- fied blade t.ips and low-carbon, powder metal, astro- loy hub hot isostatic pressure (HIP) bonded together. Figure 8 shows a rotor cut in half to examine the bond zone. ..\n excellent bond was achieved. :\ddi·· tional rotors currently are being machined for engine use. lOOl TYPICAl. &mill ltJllf Figure 8. Successful Dual Alloy Turbine Fabrication I~chieved for S,GTlOI Program. CO!vUJ.USTOR - Development of the .S,GTlOI ceramic CO!rtloostor has concentrated on analytical modeling of a lean-born, low~mission, fixed- geometry combustion system and evaluation of can- didate fuel nozzles. Based on work conducted through "IASA and Garrett in-house efforts, the AGT ceramic combustor design is evolving to a lean-burn, low-emission, fixed- geometry systt'm. Numerous geometries have been analytically modeled using fI.IASA information, Garrett in-house efforts, and cold flow nozzle tests of the l)elavan Simplex and Duplex nozzles. Figure 9 Figure 9. '-'odified Simplex ~ozzle. de-picts the nozzle configuration selected for contin- ued ;"!valuation. Analysis and cold flow testing indi- cates that a fixed-geometry combustor, using a radial swider. provides uniform flow fields and temperature profiles. Hardware has been ordered both for initial metal testing and ceramic testing. Emissions testing of a Delevan Corporation Simplex fuel noz;tle has been conducted at 16000F combustor inlet temperature. Corrected combustor inlet flows were adjusted to yield the same pressure drop and fuel-air ratio as defined for engine opera- tion. To assess the Simplex nozzle system potential at actual. engine conditons, this data was corrected to compensate for different inlet temperatures and resi- dence times. The correction factocs applied to this data were based on information published in ~AS:\ T\\ 81640. "Ultra Lean Combustion at High Inlet Temperature". Idle emissions were not corrected for highef" inlet temperature and residence time "ince ~ASA data, similar- to this condition. was not pre-· sented. Results of these tests are summarized in Figure 10 for steady-state points. The emission indices shown are based on a 36 mpg urban estimate using DF-2, whidl is consistent with a predicted Combined Federal {)riving Cycle of 42.8 mpg (DF-2) for the AGTIOI installed in a 3000-Ib inertia weight vehicle. "I"hese results show that the lean-burn fixed- geometry combustor has excellent potential of ~eet ing pr~:ram goals. R.EGENERATOR SYSTE\-\ Regeneratoc system development efforts have concentl ated on reduction of seal leakage, evaluation of high- temperature coa~ings, and engine test support. Ford has continued worl< on second and third generation ~ lr------ ----£~~- - - -- ---:: i ~ ; SlM.1I $ItiPlEX UPlEl guPUI ~co l -~ ... - -- -- --~ii~ I CLllLJm 0011 ~ ~ ESTlIMTED fltM A"MIlUM lATA 1_ 111 .1401 fOR Rm CO~DI1JONS illS IIUSIlI!U ,atUIS X ' • IfItIIIS ES!lIMTE' fill EMSlIE tellOlllOf1S AT TUIlIIIf IIIlET Figure 10. Element Rig Emission Results and Estimated \too II Engine Emission Levels. seals. Second generation (Phase 2) seals involved the addition of a third diaphragm to assist in preloading the upper diaphragm against the engine housing. Static seal leakag~~ tests showed a minimal reduction in leakage for this configuration. Further investi- gations indicated a need to ioad the lower diaphragm and retainer against the metal substrate. This con- fig uration, identified as Phase 3, shows a marked improvement in static seal leakage. Recent tests conducted at Ford show a leakage of 4.4 percent compared with a program goal of 3.6 percent. Developmenlt of high-temperature coatings for 2000"F operation has progressed. Ford has evaluated 14 samples and hilS accumulated 'over 2000 hours of test time. Of thE' samples evaluated, the GE super- alloy substrate and Ford 1-112 coating appear to satisfy the 2000"F objective. -\ summary of this regenerator development is provided in Table 2. Table 2. Regenerator Hardware on Test State-of- the- '\rt - Effectiveness, pe 'rCf~nt 9(). I Temperature, OF IS 32 Leakage, percent 7.2 *~'rojected from previolls test. Test Result 93.6* 2'l00 4.4 Pro gram oals G 9 3.9 ,- 2 'l00 3.6 ROTOR DY \JA \ilCS - The rotor jynarnics pro- gram task has developeonents, as shown in Figure 12 have been received from the leading United States cer- amic centers (Ford, ACC, Carborundum, and Corning Glass Works) and 'IGK in Japan. TIle good progress in rnaterial and processes development have made it possible to accomplish the component development activities described below. \\aterial compositions include silicon nitride. silicon carbide and lithium aluminum silicate. Ford and ACC have made good progress in development of ceramic turbine rotors. "-fter successful spin testing without failure of non-bladed r.:>tors to 115.000 rpm (ACC) and 134,000 rpm (Ford), efforts during the past year have concentrated on developing bl'ided rotors. Earlv blaeen under~oin~ rnechanical screening tests, therrnal screening tests, and structures rig tests in preparatiol~ for engine development testing. The firs~ set (49 pieces) of ceramic components were asse-r.oled and successfullv tested to 1600°F in the structures rig shown in Figure 13. F:ntering into the next ;>hd5e of development. several ceramics structure~ ":lve been successfullY !este-d in the thermal screen.ng rigs to 2100"F. This effort is tn preparation for structures rig and engine testing to 2: IJ(f'F ("00 I Complete design goa!). C:O\lPO"lE'IT TEST EXPERIE'ICE - Outstand- ing progress has been demonstrated on the aero- .J , . ..; Figure 12. AG TI 0 1 Ceramic Parts. Figure D. "GTIOI Ceramic Structures Test Rig. dynamic, thermodynamic and endurance test rigs. As shown in Table 1, over 3700 hours have been accumulated in :\G T 101 component development .o\s expected, the bulk ,,! !~.: !:::~~ hours have been accumulat,~ci on the enduran<:.e ~egenerato'- ~al wear rigs. Aer·odynamic performclnce rig time has DC'!" limited to that necessary for data acquisition. Final performance. and endurana~ capability must be demonstrated in the power section tests. POW:ER SECTION DEVELOP\tE:-.IT - Assembly of tfw parts as shown in Figllre 14 for the first build 150 Table 3. ""GTIOI Component Test Experience Accumulated- Rig CO'Tlpressor IGV Flow Rig Compressor Rig Turbine C.:>ld Flow Test Rig Combustor .""uto Ignition Rig Element Rig '-"olin Combustor R.ig Re3enerator Cold FlolII Regenerator R.ig Hot Flow Regenerator R.ig Ford Seal Wear Rig Cord Static Seal Rig Rotor I)ynamics Rotor I)ynamics Rig Hot Foil Bearing R.ig Foil Bearing Test Rig I ':::;~arr.ics Hours Through 9/30/82 42 67 122 68 19 102 38 2020 955 121 11 167 5 9 Thet :roal Screening L Structure,. ~ig '~'---rIT-O-T-A~L---------3766 Figur'e 14. AGTlOI Parts Display_ of .-\GTlOI engine SIN 001 began in June 1981. The engine was motored to 30,000 rpm on July 30, 1981. Weeks ()f cold and hot motoring followed, to verify mechanical integrity and establish leakage from the high pressure (HP) to the low pressure ': p) portion of the engine. With external ducts as shown in figure t 5, a leakage evaluation was conducted using a helium Figure 15.. :\GTI 0 I \'od I Configuration With External Duct. flow-seeding t~'Chriique. shown schematically in Fig- ure 16. Whei'l using this helium flow-seeding tech- nique. the C01ITllX'es5or and/.x HP regenerator inlet flow is seeded with helium at selected injectioo ports. This se~ed flow is due ted from tile test cell after passing through the HP side of the regenerator core. Condi'~ioned combustor inlet flow then is introduced to the burner. t\ proper compressor and turbine flow match is maintained and fuel is intro- 151 Figure 16. AGTl!l1 ' •• od I Build I Test lA, Regenerator Leakage. duced, as required, to control turbine inlet tempera- ture. Regenerator seal leakage from the HP side (seeded) to the LP side (unseeded) is determined by means of mass spectrometer measurements of helium concentrations in the exhaust. f)uring these tests. TIT was increased to a maxi mum of 1250"F at an engine speed of 50,000 rpm while leakage was monitored. Helium leak testing revealed that internal leakage was excessive; about 35 percent of compressor flow. Therefore, further testing was deferred until leakage could be decreased. Fuller's ;:arth then was introduced into the compressor inlet to ?~ovide visible indication of leakage areas. The engine was removed from the test cell for disassembly, inspection and analysis. The engine was disassembled and progressively photographed. ~o evidence of damage was present. Internal leakage, as indicated by Fuller'S Earth traces, was evident at the flipper seal, regenerator seals, turbine shroud piston seals, exhaust hou<;ing ;>iston seal and numerous instrumentation penetra- tions. .\ c.oints shown :n Figure 17. Figure 17. '\GTl'J1 Le-ak Path Designations. Improving seals around instrumentation, adding springs to seat critical piston rings, and ~Ilbstituting an AS (alumina-silicate) regenerator core manufac- tured by Corning for the more porous "'AS (mag- nesium alumina silicate) core allowed the static leak- age to be reduced to approximatelv 15 percent of compressor flow on Build 4 of SIN 001 engine. This leakage would further reduce under the hot operating conditions and was considered adequate for initial engine operation. The engine was installed in the test cell and a smooth start and acceleration to 50,'l00 rpm was made. The TIT was adjusted to 1000"F and helium leak testing initiated. Compressor flow and back pressure were adjusted to approximate corresponding turbine conditions, including the measured internal leakage. The TIT was increased to 125O"F while decreasing turbine pressure to maintain a steady- state speed of 50,000 rpm. A match of compressor flow and pressure ratio was obtained with the turbine by adjusting the compressor flowpa~h back-pressure valve. This match represented the engine self- sustaining conditions both for the turbine and com- pressor even though the flow paths were separated. The engine wa$ shutdown and external ducting sepa- rating the compressor and turbine flows was re'llOVt j and replaced with a duct connecting the flow paths as shown schematically in Fi~ure IS. Figure IS. :\GTlOI \100 II\uild I Test 113. Self Sustain. C'> December 15. 1981 the engine, shown in Fig ure 19, was started and accelerated to 50.000 rpm. Idle fuel consumption was approximately 3 Ib/hr using JP-4 fuel. This test provided the first self-stlstaininl; operation of the .-\G TI 0 I as a com- plete unit. One hour and 58 minutes of self- sustaining o~£ation was achieved on the first run. Testhg continued on the engine into January; electronic control functions were modified to improve lightoff and control functions. On January 5, 19'~2, some members of the House Science and Technology Committee ar:d JPL visitors watched the engine op'~rating near idle condition (53,000 rpm). COfltrols development continu~-d through January. Testing was terminated after the engine reached 80,000 rpm and a speed control instability was observed. Te.ardown revealed that the turbine shroud had radially shifted touching the turbine rotor and 152 Figure 19. AGTIOI Power Section in Test. <:3using foil bearing distress. The turbine shroud support bolts were bent and had not slipped in the turbine shroud slots as intended during thermal expansion. -\. redesign of the turbine support SYstC'T1 wac, ;>erformed. The jesign features a radial flexure system r:onsisting of mne beams supporting the tur- bine shrn goals. "i'J 002 engine which incorporated radial .lI,d axial clearance probes for the compressor and turbine entered the test program in "ay 1982. Build 1 of this engine provid~j limited data as an abnormal ~otor dyr.amic behavior '01/,15 observed. \tinor oii leakage in the compressor inlet ·,v.lS observed. Between \tay and September : 932, tests vf one build of S/'J 00 I, three ouilds of S/'J 0')2. and t'.vL) builds of Si'J 1)03 were conducted. 50n'le abnormal rotor dynamics and ·ninor C'o'Tlpressor and turbine rubs were experienced. Inadequate dearances ·It t"le rub locations have been corrected. -\dditional staOI- li 7 ation of rotor -n01:ion is '>eing evaluated both in the rotor dynamics rig lnd engine test beds .. .)n September Z3, I q32 S/'J '),J 1 ~uild :- .<.'as satisfactorily .lccelerated to full rated speed .)! 11)0.1)')0 rp'll. This unit provided furt:.!r supportive lata .)11 running tur:,ine clearances. '\v :nid-0ctvoer 1982, all three engines "lad ~n run to 'lear ~:.lll speed (97,1)1)0 to 11)'),')00 rpm) .lnd '1ael ..iccUlnul.ltN vver 90 hOlJrs and 135 starts (see Taole !o). Table!+. Testing 11lrough October 15. 1932 Power '>ection I -; "er;al \jwnl)er "t.J.rt" .--per ..I!::H~ ;.-:1e 1 I ..; ')01 I'JI . ~ r .... rs ~7 ':1111 ')02 'il) :~, '1rs 24 'n!n I 003 3!. I 3 'lrs 53 '111" I h,rs q 'n1l1 ! Total 135 --.---- ____ . .-.-J To verifv ;:>roper oper.Hlvn. :estlng :">ese untts, .... 111 cvntlnue 1urmg t"e .... ext few ...... """',. Engines ">/'J 'J')i and ~!\j ')02 :h"n .... tll 'le 'Jtlll!.eC ..I' :!eveloprnent test ':Jeds fc)( ·t·~.l-nl'~ ·,-o'npo:le..,:<;. -\fter engIne ">/V. ,),), ?("r!vr·n.mc(" .5 ;",r:f:ed •. : ... 1. 'le s~!pped later t'1IS ,e.lf ::> lPL .15 :).In _'f :'1(' '0!,' ·\GT progra"1. -;t;\\\t.\RY Progress of th~' \ ... ~ T! ') I 'er .l:O:C !eveIoD'nen: dfort has ':>een excellent. r .... :s., " .... r:fled ')\' t'1,. ::K: that ..ill ceramic ?-lfts "3'(" 'le<"':l 'l'<:'-essbih :.1")r·, "':~lted; :n sorne C.lS~·s j, lhxe :'1..111 ,)ne ': .... "l(1tr.lC!..)r. These parts .lre fabricated fro'l) jlfferent ·'later:ais. .lOld v3rious '"anUf3ctl1flOlg 'neth,-,.:!s. W'llCh enn.lnCt'< the potential for j,llccessf'JI :er.l~lC .lppllC3t:.)ns. '53 Garrett test rigs have been valuable tools in r"ois technology oevelopment. In fact, the structural parts already have been successfully tested as an asse~blv over simulated engine start and stop cycle<;.. Cerarmc bladed turbine rotor jevelopment bv -:era'Tlic con- tractors ~s provided rotors capable of f·..I11 operating speed. TIlls \l,a5 considered the rnost diffteult tech- nical challenge when the .-\G TlOl program starte j three ,ears ago. Some said it could 'tOt '>e .1one. Compress.)r .lnd turbine .. erodynamic perfor- mance is another significant accomplish-ncnt. T'1e 4xcellent efficiencies demonstrated at idle and cruise Nill ef'l)ance the Combined Federal Drivin~ Cvcle ~as odeage projections. \Iso cf significance oS rel'A<'le- rator development, ·"I)ICI) has provided lea>,age~a ~s approac!'ling pr'Jgram objectives; t'le -om!lus.tor .. ffort i~ e-c.Jally i'Tlpressive. -\t program :nltlatlon, viriable l1,;eo·netry .vas thought to 'le re-qulred to 'nee: future emissi.)Il gOoals. '-lowever. ievelopmem to 1att" ,ndicate's !"'at a simole. lI1expem,,~·~, :ixei- ~eo'ne!rv cO'Tlbllstor 'las t"le potentIal !v.,.,eet ill ''''1:>510n levels. \5 :>reviollslv stated. the ·\GTI'J! e"l,,:'1e :s "10'.10 .1 :est 'led for evaillatio"l vf r:eram,,: .ind .)t·'le~ :f>c',nolvgles '>elng 1evelol'>ed. :)ver :'1e ')as! .,.ear. :,~q:ng 'las Drogr~'ssed to :!'Ie ;:>0l11t ... ·hen' 'net 11 engH'e5 "'ave 'lOW :je-nonstrateri bII sDeed :>oer.lt~,)"I. \Ithough t!1e engine test 'led ,:hecKoerlOd "'as ')een k'l'lgth\. the time spent 'las ">een ... ·ort·1'"I) !l ... \\.l'ly ::>r . .)bk~·"'1s ex;x-r:enc(""~ ., .~, :1,..".,.,:- ·~t~:.l.~ '~""g~'"':I?" \0 .~j i.l._~ ~~suite-1 .fl "er..l''''lt< J.),r~'" ~..l .• ·.~res ..l.nl.l ~l'sditll1g e.;;:>enslve repairs .ind b.dure .n" ... "t!i?;dbJr)"' . T'1e :'l<.'X! ;tep ,$ !.:J evaJuatt' ·:era-nlcs .Cl :-,e engIne :e'it jeds ,mder actual ,)perat.ng en\,lron·.., ... nts .In,~ '~xper :ence .lctllal :nter faces '>etweeo ·~~tdl .H'<1 .1!'1,'~ ·er.l·T1!C ;MrtS. 'T'115 ",~ r: ";1 e"lgll1e :e5t 'Jed .S .l '''·' ...... .1L)o .of .lH ';>snltlcant :>r,'gr.l:n technology l.j\'.l,'",('e'nents. '!''1e ';Oo-~':>r' ... arcl ;J(.:Jgra:n :t'1rollg'\ ~Y! 4~~) :.) 1eH'!OD :"" ?'h~m<.· ,vIII tec"'nu':a!!\' ')(" .1 -·, ... I!e·lg,,,,·g effor·. \i :'1(\'J~;"o excelle'lt ;>rol;r(>5s 'us ""-'en ': 3d... "1 if' ·:,,~v ~r,)nln("'nt vf .Jf)c~r t •. -un ~i.lnd !n~. ~'1e '"'.1. : ... )r -~.l!- ·.~r!g(" ,t·!! !..~'\ .1he.ld. t\r:ngln~ '-e·r ... t.· ... '!;': ... ~~~ .... : .. ,fI;'"~ ~t,.r~~I.)lo\~\ ~~!e~n~·~!S .... ) ...... l!.'i!..lC:')!'·\ "~"l: ~'e. .· .... v, .... ' .... :~1e ("r)g.ne !~'\: ..,eds. -In{i :"r~"'\':'~l:-1t: :'~e .. A .. ~(b~~'t-..,· .. ~,l(,,} ·~~ .... "}ri..y·~ .. ~· •• ':-'T).SS:0n ~(",\'~!"" •. ):1<1 -oI.:"(j,.I .. ~ :'0'''' .... ". .. .·:"'\ei). ... \.·~.le ':'l.lH1Lllrr~n~ ~'-'e ......... l.~~! Jet -.l~:!":;:~\ •. <' ,} ~tf~." d!. ")lj! .l\.~~l~e"v,)~le :..iS~. :\.ase<1 ~)n ;xo\l;r ..l·~1 Jr()~rt."'s,) ~ .. ) ~.j :t .... ~ ~.~ \\.~ r' -: . :(",3, .... , "'dS '-..JO!.dence :~3.r ~)\"~"'r.ljl ~rJ~r lJ"~ -; :"',l!S. \' ... ")(" .l:l-"1!e"\"M., T""'U"i .. ')\' , ~S{;. :"'e ~ 'n;!f"''; '~..l~es ..lJt .. ) '\du":,'r\ \:;!~".71 -l J .......... l~:, ... n :,,' "",)\',,, ~,-""..\-_i~~'t, :JrY~:;- ~;Jn .\- ~Cl :~1e ';'..l~1 ~JrtHne :~I-'":rh).0~\" :f~\,"t"'l.,)Ot"'4015, .,hdt kInd Jf turbine (;ledrance WdS medsured in the AG-:- engines run to rJdte' Are JUU talking engi ne bu II d : 1 edrdnce or -.:omponent ,"unni"1g :1'dranu~ jUring engi'le :)pe'"dtlon' A: JUrl ng engl ne testl ng, .,e had instnllN:ntat10n to 'leasure the :ranSlcnt :leal'ance lurl'lg full-speed Jperatlon ana ,n fLill tenptrature ':xcurSlons, -:-he ~learance lidS see" to :hange out uf :he ~l"1jet" ::;f cO :rlOllsandtns 'rom ~;)l j 5tart ~:) ,~ot "Lln'l'~9 :Jnd':~0IlS, ~0 :hat ::leans:o j(tll-?ve .. ur :drgt!~ jvdl )f :~. ~r,ousJ:ndth5 "unnplg :ledrance '"1 tnt' :urDlne, \'Ie "dd :~ .. have a build clearance of approxiR~tely 40 tilOusclndths. Ouri n9 the 20-trli nute transiEmt, the clearance would decrease from 40 thousandths down to 10, in the coopressar, the clearance change was mllctl less in the order of 13 to 17 thousandths that it closed. So you can build within 13 to 17 thousandths of jour 1esir~d running ': I earance on the coopressor. 0: ,Jim Nitpier fron Solar Turbines. ..hat materials were used in the rotor and did you have more than one supplier for the "otor? Are you talk i ng about t!Je r.Jeta 1 ,"otars or the ceraml c ,-otors? ~erami c t"otor dnd rig test, A: -:-he rotor that we used in :ne rig testJr aerodynami c tes t i ng Wd S the '":I(>ta I t"otor built to the Sdme contour and profil~ ~s we would eApect ;n the final design of the ceramic t"otor. But as far as the :erar.li: rotor' and the people .mo are OJOrking on thdt ,Ire concerned, we 'ldve For~ working on sintered t"eaction bonded silicon nitride 'J'" the '-oear ]nd we '1ave ~i ~f'sedt"(n _dStl1g :oopallj .. or~~'1g ,n ;'~ter~'l S' "~on '11 "=,...1 ':t:~ ): '!dd ~hose :Jeen spIn :este1 iM ~ot ,t" :0::11 test s? ~: fes. Early In :he Jroj'~.j.r.l~ 3 :- )r~'1 .... O':.:;r Jne )f the firs: ~nl!S :he! Jt"oce5se1, .. as ~':)I J SP1'l ~estet1. ··he~_} we""'_· ;)f",t:: ·ljwS ." ~he :1~d(]eS "Ol' .... C'; )efor'"" ~"e..' ~ven S:dr!e~ tile test d"fJ DU" • :rle :)] J::e : 1 ~s h't JO 1unng the ~est. :Jut :helr '-':ltor 5urv:'~elj JV'}r 115.';00 . vI:' 'P){!"::3:;"j ·:~t'i "d::- ,.: :) ~ :; {' ."xm ~"r~, Advanced Gas Turbine Technology Development: AGT 100 Systems and Components ~asn .. -\(T )"tr'Ht" ~'C"!f .. 1 "'H·"t~,)ft .t}!}A" ih~ .. tpe-...t· .; ..... " r.l I ~t' I1T'!> -;"'lrtJOT3t''CUTT. "t .... d.-v," 1 00 1 ~ .. : h .. l.ivaoc .... ,i ':. .... ~:nn,)l,,).1!ipc;. !:0 "'1.1k." ~h~ ~a.<; !:'lrh11+> ), lJi.)~l~ llt~r-:'lat lve :.., ~h'l? -;parl( :''':!'ll:'l,)n .1nd Jt~'iei t:."n~l:1~'i )f thi:~ :·It·:r~ .. ·~,).11,. 4+-~ ':~ ~l;.'...l~ ,~ ··~.l''''· ·~~·'··1 .. o;t Ijll";~···l : 'f :'1t!~ ''''I ,· ... v. ..", .... ..,: i. .... r '.1 ~ ... : : ~ ·;l.:n-r1.S~ -":II'''W :··~~~1)l)~y "':tJo"'J~nt<; .lr~ "V,l:1t'" ·.Y.np,)'~·:1t..; l:1J 'll~n-",!:'''''':l'''~'':'' ):lp')n~nt 'i 4 _ 0;" r .un 1. .. ..:. 1 ~ : ~ .,,", ~ 1 t r 1. j ~ :"' .1 :- ~.;. I :-." 1." i;"" .... ~'3...1 .. : : ir:>l:'h~ ...: \!:lP'<-"'tne'1! :~ ••• ",: '\O'~··~t '-..t ... 3a-(t. .. j :~..:~ln ... )l.)~v .~1 :i··St'" : .... , If.',)"; 1:-~1: .. "lI.p~r..l: Jr~.·s .1ao.l ::'"'t~"·:h;"r,lt _'r ~ i .. ,-t : .0t!l- .''I.·rl':.-.&:''~S ;;. ... :jl.:'\Jt! ""'-~r'" : 'W .. ~~,,::.~~..:: ~ .h.~ ';1- ::1 ..... ~~rJ·(·..:~ :.1:; ··l.lph..J.:.;l!'l .. ..l !.--v't"'':'''pm.-:-:1t ·"r.l~l.": 10..1 .).~r').,j""'1..r:ll': ._)Qp..'n'~:lt .. 1$ ~'1)wn 1.'\ H. E. Helms aod R. A. Johnson DetrOit Dine' ~Ihson C)IVISI()(l ot Gt."r.('f 31 \4otor1 C,Jrp ::'h' :.ICl:'l~ ';''':~ .. lo:.l·ji·~_ ~·x:>.'r.;.·:'l~.l~ ,:~~'1":"1: )! Lit.l ~1.1S 11)W ·./"rl~l>'''d ::9' JJ-\ tO~""'.1':-;. i~.~ t~t' r..lbrl::,lt l·)n ': :'~., ':1)!!'>' .' ...... !~,! .~: .... ~r.lt ... :~':t· .... ~ ..: ~;>\1., .... .,t=-" ~:,(, i ,.,!~. :~V\ .' ,:,", 1-:,: '. ·.t~ll.rlt: ~,I:1 ,! 'Iffi!), ~ ~1"":1 t.; _:1t.., 1 : ! .:: ; ,:".> ... .,; '1 ... ··1. l~t"!'Jl J.)W~!"?.l:1t. . ' ~ •••• • •• r '-":):-'i~.·"'" :-"l~ ::--.ln~l·":'t .:,,; ';':··I~.·- ': ):., .... :--.:, t .': • t. .,.~ - ,"","; ",' : : ~ :,"": : . . I , ...... :-. ~ • 1: I , :' :. •. , .,: • ~ :: .' J'--:! .:"':' i: . ". :'~ .. ' :- . .- 1 -: • ...... i~i._ .', ... : ..... . '~k. : .~., • j,'~ - ',-- -' .. ' : ~ • .• l '1,j ... ·'.~r: )r:1.il:~ ... ' ~ In....l: ....... :" .... V.1:..:.a t ~ ,~, .. 1984 Pontiac Phoenix with Gas Turbine PONer Train AGT 100 ., Multih .. el capability .42.5 mpg fuel economy fIii Iulkht'ad , ~lurnir,um siiicate re~enerator .., ~our ~:irconia t~erm.("ll ~)arrlt?r rln~s 'i.:rolJ: "l!ounti~q , .nsulat.on materIals "'1~tat ..:() .. ~ponent ':l i'1 not -;ect 10n fl J\J :>.ltn '1ar-~2':"1) ~aslflt"r .1nd ;)ow€'r turblnt" ~o : It" oS -; t .1 1 :1 ! e ~ " " t ~ ... ~ 'i ~ 8 <'3 ~ a S 1 f 1. era n.j :> )Wt~ r ~ 'lrt>ln~ -;(: r<)Ii..; :-'1t. J::1-\ ,lppr'~3ch t,) '":l.ee-t lng OL,'.ltram )bl~("- ~ "t..s, ~ ~ ~:'I i. :1C,)r?0r~tt!' 'it.ltt."-0f-tht!'-art .. 1<1."1:"0-' Ivn.a~l": l~ ..:~r.)Uli.: : . Y!I.p'l..1nt!nts in :he ~ngln~ 15 t~~:-· .tr~ Ivallabl~ and to run :'0 ,:()~apet it tV~ '::lr~lnp inli!t tempe-ra.turt~ levels from tn~ ~ .... ",- .: l..:lnl:l>t -It !hf" t~st ing after shakedown test- ,'1...:,. :-, ... ~ :'l .. l;'1n •. ~d ~ Jr')l:it:' ~nl~t tt."~pt!'rat·.1r(' ~ .. :~7'>~F ~ Jmd the l.rlclH'3i;.H\ of -:-It!camic c •. nnpo- ',ents ,nitlllllv i~ consistent with rig and '>n- ,1;1"" .,xper1<'nce in the CATE progr .. ", and from th .. n~ 'lualifi.:ation testit\!1 ,)n!.GT 100 ,0.'1)- ?"nents. f'ulture elll\:in .. t .. st inlt wi II introduc .. i!llpr~)ved aer·od,'na!:ic ~\Jfmponentq .100 ceramic ~.,..ponents a,s rig :esting proves their engin.- readiness. Proi~<:tions for the next Year $ug- "est ':.)G1plet ion '.>f :&ech;;,nical shakedown teslil\!; Jith the ~eometry descrihed and at the 197soF tu!'birte inlet te ... perature. Ceralltic cO!ltponent fabrication progress Sugg .. stll gasifier rotor ~r !croll testing verY late in fY 1983 ~r ~arlv in !'1' 1984 with all ceramic compoMnts and 156 TE81-7023 turbine iniet temperature at ~JSO·F (reference ;>ower-train deSign Ie"",\) in late IT i9R4 or ~arlY in f'y 198~. Component ~fficiencies for the initial ACT iOO configuration are these: Initial Closed clearances ------ ~ompress~r 78Z ~OZ ';.lslfi .. r turbine '13."~ '1.7: ?~"er turbine ,H!39t ~egt'nerator ~4! ~4t '~,X!lIllon ,1eveiop_nt experi~nc .. dictates ·'.."pen'" ..:learanc'l?s ·Jhi~e ~n.gin~ ()p-er&tin~ .:har- .Jcterlst1.~S a:r-e' 'Tlapped and tr.1nSl~nt ~ehavior These .:learances are :h~"!'n ciost"-d t.:> achi~ve 0ptimum performaoc~ !-r .. ·}(a thp ~tl.gln~. Fi~ure .. :>hows 1 pfl)gresslJn If "1ors~p.oVt"'r lnJ spec 1 fie !LJe 1 ,,: .:In.s.uulpt ion values e"pected ,,"th tht> lQ·)·F and 23S0°F engln~ c~nii~urations. ~"erfonnaoce analyses ~re ':I.JMuc.ted to ~valuate the effect ~f ',arious .. ngine ;>aram.e- ters ,)l\ fu~l .:onsUDption. 7his. infor.aation quantifies the effect ~f each ;>ar ........ ter and, among ~ther th ings, ind icates where ;>rograra resources and eff~rt $hould be directed for ... ax i.....". pavof f . The height )f ~ach bar' represent s the amount of ;>redictions " .. ., ~ased "" ~he aerodynamic perforuoat~e values frolll rig tes~s in combination with the temperature ll3;O'f) allowed by cerami"s. The results show a ~OID hined driving cvcle fuel ~COno~v "f l6 ~pg. CERA.'4IC CCJlMFONENT !)fVELOP~NT Ov .. r three vears of oerami: effort in the At~ 100 program ~as resulted in the ~omponents shown in Figure 6. Success of the AGT 100 en'- gine is dependen.t upon the success of these ceramic cOlllponents; accomplislwDents over the last year have brought us closer to our goals. The most difficult component to address has been the tUI'bine rotor, largely because of the fabric at ion I)roblems inherent with the thick hub, and the high service-strength re- quirements. This year we have seen rotors in cold spin tests exceed 110,000 rpm, or 127% of design speed. Recent data from cOIllponent snmples show we are ~pproaching test bar strengths in compli- cated shapes. This is a resul.t of a new die incorporating fElatures to imprOVE! the strength of the part. Bllrs from these ne,,, rotors show at rengths great.!r than those of the rotors spun to 110,000 rpm. Additionally, proof tests cull out the lowest !ltrength rotors to give in- creased confidence of a popUlation lIith a higher average ,;trength. Advancement" were made in othE'r cOUlponents. The injection molded SiC vanes successfully passed 10 therm.al shock eye les at heat ing rates of lOOO·F per s'~cond and were subsequently run in the engine. In this case, as well as in other component work, the s~ccess lias attribu- table in a larg·e degree to the experience SCROll TURBINE ROTOR TURBINE VANES SCROll BACKPLATES gained fI'OCl the CAn: program and applied to the AGT proglraa. The combustor (alpha SiC) design was modi- fied to red~:e the number of ceramic parts from five to four. In rig tests the emissions were a factor of 10 lower than goal, and the com- bustor operated exceedingly well in the engine test. A new scroll has been designed and fabri- cated and awaits testing. Though basically slip cast, it is fabricated using pressed and injection-molded parts to its final assembled configuration. Insulating rings (thermal barriers) of zirconia have also been fabricated and were installed in the engine for the testing. There have been no problems with these parts to date. Finally, a large (14 lb) LAS exhaust dif- fuser and regenerator seal platform was fabri- cated by Corning, tested, and installed in the engine. Static deflection tests were run suc- cessfully, and the results agreed well with the analytical model. Th a ~emote data ac~uisition center. Data are recorded at approximately six readings per second. P:retest checkout inc luded careful at- tention to the engine control system. All ac- tuation systems were operated and calibrated; the fuel system was also checked and nozzle flow l-ates measured. ~{otoring tests have been completed. Both the starter and the dynamoroeter were separately employed to drive the engine. Sound, vibra- tion, shaft whip, and lubrication system checks ""ere :tlade during thi~ running4 Pi lot nozzle light-offs have conslstently been successful. Thev were followed by start nozzle tests dur- ing which combustor geometry positions and nozzle air--assist pressure level were varied. Sc hedu les we re ident i f ied that produced suc- cessful start nozzle light-offs. The en:gine is currently being reassembled following minor modifications made as a result of mechanical shakedown testing. ACT 100 COMPONENTS AND SUBSYSTEMS Technical challenges of the ACT 100 engine program involve various aerodynamic components as well as ceramic and other structural coaapo- nents alnd the electronic control system. In 1981 the primary component testing effort fo- cused upon aerodynamics: compressor, combustor, turbin~~, and regenerator. Achievement in 1981 of the compressor and turbine goals required for thl~ initial engine build allowed 1982 ef- forts to be devoted to further improvements in the combustor and regenerator, as well as to .!xperitnental evaluat ion of ceramic eng ine com- ponents and the electronic control system. Figure 8 contains a summary of the testing now c~npleted in each component area. REGENERATOR DEVELOPMENT Regenerator development erfort has concen- trated on the fabrication and qualification testing of the components required for the first engine build. Successful completion of these efforts resulted in the assembly of the regenerator system for the first engine build ,)n schedule with rig-based performance charac- teristics matching the first huild require- ;nents. An imporr.,nt :unction )f the regen"rat0f cover is to provide a smooth transition of flow from the compressor discharge air deli- very tube to the regenerator with minimum pressure drop and a flow distribution compati- ble with that of the regenerator gas-side. improper matching of these flow distributions can adversely affect regenerator effect ivencss and engine sfc. Figure 7. AGT 100 SUI on test stand. 100 -COMPONENT .-=nP • COI~PRESSOR COIMBUSTOR TUIWINES GASIFIER POWER INTERTURBINE: DUCT REGENERATOR COLD SIDE FLOW DISTRIBUTION HOT SIDE FLOW DISTRIBUTION SEAL LEAF LE~~KAGE HOT SIMULATOR RIG CERAMIC SEAL. PlATFORM EU:CTRONIC CONTROL SYSTEM CElRAMIC ROTORS EN"~iNE STRUCTURAL ASSEMl!3l Y CEMMle TURBINE VANES GASifiER TURBINE POWER TURBINE BUILDS 5 7 2 1 3 8 1 4 2 TWO UNITS 2 BUILDS 37 SPiN TES1'S ONE UNIT HOURS = - 286 132 204 26 239 110 72 35 220 20 95 -1439 ONE SET PLUS SPARES ONE SET PLUS SPARES TE82-5885 figure 8. Aerodynamic component and subsystem rig status. Combining measured flow distributions with the disk characteristics, the regenerator ef- fectiveness was calculated and a significant loss relative to uniform flow was identified. ~odifications to the cover have been modeled and tested, as shown in figure 9. The result- i ng flat ve loc ity prof i le restored calculated effectiveness to within U: of that for uniform :10101 with essent ially no increase in pressure jrop. The first engine build of the ACT 100 will ~e used to evaluate starting Characteristics and low speed operat ion at reduced tempera- tures. The regenerator systelll hardware selec- tion reflected these operating goals by pro- vidintt reduced low power leakagE~ with a high c lalnp seal. The inboard seal incorporated O-l'ing backup at the miter joints and full perimeter O-ring backing of the outboard seal. The entimated regenerator system leakage and effectiveness are also shown in Figure 9. Correlation and analysis of all available leakaue data have resulted in the indicated breakdown. Future development efforts will be directed at tho-se areas where potent ia 1 for iraprovet:!llent exists. r""",ediate l.rOll!lising areas are disk internal leakage and the seal leaves. especially the miter joints. 16t ACT 100 EXPf:RlMENTA.L COnTROL SYSTEM The control systelll utilized for dynamometer testing of the ACT 100 engine (Figure 10) will allow manual open-loop control of gasifier speed, inlet guide vanes, burner variable geo- metry, and power transfer clutch. It will also allow adjustment of the turbine out let temper- ature limit ~nd manual control of the timing ,)f fuel flo" transitions from the start nozzle to the main nozzle. Switches, lights, and me- ters are im:luded in the control console to monitor the engine performance and to allow the control console operator to manipulate various engine conditions. Fuel flow -is the only engine parameter that utilizes closed-loop control, where the awount e,f fuel flow is de-' termined by the electronic control, nit lECU) software program. The Keu is a modification of an existing digital control unit. The software program was written uging an in-house system that per- aits modifications to be made quickly and ~as ily. This characteristic was desired to pro- vide I!lllxi1llUlD flexibility to the ACT 100 engine development program. All components of the system were individ- ually tested ou various test rigs. The fuel HOT RIG RESLILTS LEAKAGE DISTRIBUTION 81 LEAKAGE I "" 6~ <161 EFFECTIVE NE!;5 , 92 ,~. i ____________ -fsu 1 HOW i ~-~--~.-----~ LEAKAGE - ...... ----------------+--- IDLE MAll POWER FLOW TRIP PLATE 50 'AESH S.CREEN ---~.:;;,-~~-- DISK ~--~~~- .--=~ 4 5 Q • POROSITY ~ LAMILLOV ..J . ~c-.·~C. -=-""C-=-"--~=~T:l-- 20, vELOCIT'r 'Ot ~~ FT SEC o~-- ••. --.~ .• ---.-~- 2 4 6 8: - --------.. -._ ........ RADIAL POSITION - IN ACCOMPLISHMENTS PERFORMANCE ,p ~ DESIGN GOAL P P PSIG ACHIEVED INITIAL ENGINE LOW-POWER GOALS ON HOT RIG IDENTIFIED MODIFICATIONS TO MEET MAX POWER EFFECTIVENESS TE82-58B6 Figure 9. Regenerat0r rig results. CONTROL CONSOLE ELECTRONIC CONTROL UNIT OMPOt.l.f",t ~'l)"""ROll.:Of'llSOi.E tl(C"RON,,: C~lROt VNIT sUf l ~f'l HINt.. lO ... ,qOl ~"11.01 ~ut l ... l)t.lHlt,."'ll VA.~N "'QZllf ,C(~TtR-aO()vl STAAl·WZllt SOlI NOtO$ R;£ G.l..H...A T OM "Al\'tS,AAiSS (MtCa Rfll(J"\ RfS1JV(HONS S"ST[M TE'SlS (O¥PONe,,,, H'JOAAUllcsvSTl;u7"SlEAOV s.TATf"'Y~~~s~iN-l- 'lSfS J lO~' TI£STS COVQIN(O ("0"'8IN((\ S"Slf" Sv$tE1It'I • G .. .. • • .. .. • .. • .. o • • G .. .. ~ .. .. • - G- .. • .. 0 • ____ ... u..&o __________ .f'"_",~~ ns:·~ss: Figure 10. Control systel!l test plan. 162 system components were next collectively tested on a flow bench. A successful checkout of the overall fuel and electronic systems was then completed. Steady-state engine operating points were tested. using the test simulator. Both actual fuel flow to the engine as well as transient fuel flows when switching from start to main nozzle were checked. Both tests show excellent correlation between predicted and actual fuel system performance. THERMAL SHOCK TESTING OF CERAMIC TURBINE VANES The AGT 100 engine design employs ceramic vanes for both the gasifier and power turbines (18 and 20 vanes respec t ive ly). The vanes fit into airfoil-shaped pockets contained in each of two endwall surfaces and thus direct the hot gases into the radial infloll rotors. The vanes have constant cross-sectional shape. A test fixture shown in Figure 11 was de- sign~d to evaluate vane response to rapid tem- perature changes. The fixture. which holds three vanes in cascade fashion, fit into an already existing facility capable of rapidly changing temperature. A 4-minute cycle was selected in which temperature varied between 1200'F and 2000·F. the change occurring in ap- proximately one second. Each three-vane set 'lOderwent 10 temperature cycles. Ei~hteen ~'lsifier and 21 power turbine vanes (all alpha SiC) were tested. All vanes survived the test without crac\r housing, these components form a pressure vessel that is the base structural load carrv- in.; path throu~h the e •• .;ine. TI,e rege:l"rator housing .las ?r~ssure tcst~d separately dnd thereic)re ""as not included in this test. The overall Jbjective Jf the test was to subject th~ parts to tb~ m .. "lximum ?rcssur~ they W'0U~ ,! ~xp~rienl:~ Juring ~ngine operation. :":le tt:st ~t::tup i.':i Sn0\.:n in Fi~ure 1 L rht.! ..:~)rnhu~t ... )r :10usin.; .. intlt.:[," gear (:d.sc. d.nJ in- t ermcu. i~lt t3 5cdr ..::ase I..:ere bo ltt."d tog(>the-r wi t:1 311 ,,)f the .lssucL.1t~J t:.'ngine seals .lnti ;:;.is''~ts tv :--,-"'rr.1 .\ ;)re.:i~ure-ti~ht structure. The dial indi..: ... lt.JrS ::1'1:'..l~ur~ the innt'l' gear ..:.asc b~..lr in~ p0ckti!t ~ . ...:flect ion ...inti s lI.Jpe ...lud compressur stlr0uJ J~!f·.~..:.ti0n. A to~al of ~l strain gages was installed 1n hig~ stress regions. Pressure was applied to th~ combust ion case in stepped increments up to th,e maximum pressure of 70 psig. The rn,'txitllum ,,,easured combustor housing stress was J4 ksi. This and other measured stresses were in good ,agreen,ent with calculated values. The '!!Axi,,, ..... stress in the inner gear case was 2.9 lui and 'was located on the compressor scroll. The maxiBum deflection in the inter- mediate I~ear case was 0.012 in. located at the outpu.t shaft b~nri"g pocket. Differential de- flection between the inner gear case and the intermediate gear case at this SlW.\e location waJl o.oon in. at maxi_ test pressure. All shafts rulV~ suff ic ient end play to acc~ate 164 this reduction in clearance due to ?ressure loading. COMBUSTOR DEVELOPMENT The combustor for the BUI engine differed slightly in design from the prototy~ model previously tested. Following rig modification to accept th~ BUI combustor, 26 hr of burning time v~re accumulated on the combustion rig. PIl.OT NOULE--Bench test ing of the pi lot nozzle investigated ignition and coo"\>'15tion chara',cterist ics. A photograph of this test fixture showing the pilot nozzle in operation at 0.3 lb/hr fuel flow is shown in Figure 14. The ignition li8its were quite wide, and lean blowout was as low as 0.14 Ib/hr fuel flow. Schedules picked for the BUI engine were 1 It-Ihl" during light-off and 0.6 lb/hr there- .1f tel'. START SOULE--The centerbody sC",rt :1oz1.:1e was tested to determine ignition cn3lracteris- tics and lean bloIJout limits at stu"'ting con- d it ions. It lli&ll also test·ed over a range of inlet temperacures up to a burnc'.:- ih!et tem-~ perature of rOOO·F to silllulate operation dur- ing the vara-,.p period. llllprove_nts .ade during this testing resulted io satisfactory starl: nozzle ~"aracteristics. '"IN NOZZLE--Measul"ed emissions and flame appellrance durins Wlin nOIl&le operat ion were very similar to previous tests vith tbe proto- type coabust~ even though an appreciably dif- ferent fuel illjection design wall used. Tran- COMBUSTOR CASE MAX MEASURED STRESS 46KSI GEAR CASE MAX MEASURED STRESS = 2.5 KSI INNER & OUTER GEAR CASES • INNER GEAR CASE DEFLECTION = .012 INCHES • OUTEn GEAR CASE DEFLECTION = .OO~lINCHES ., REMAINED WITHIN PARAL.lELISM LIMITS TE82-5890 Figure 13. Engine structural assembly pressure tescing. G PROOF TEST OF TWO CERAMIC COMBUSTORS • PILOT NOZZLE & IGNITION H,STING BuRNING TIME 5 HRS • START NO"ZlE. DIFFUSION. FLAME TESTING 8 HRS • START· TO· MAIN NOZZLE TlIANSITlON ' HR .. 101AIN NOZllE STEADV STATE EMMISSION MEASUREMENTS liND SNAP FUEl. TRANSIENTS 13 HRS TOTAl B\;RNING TIME 26', HRS AGT 100 PILOT BURNER IGNITION (Q 1,6· ..J UJ -' N N ~ 0,4-- >- o ..J 0::: 0- o , - IGNITION IN LESS THAN 10 SECONDS e - IGNITION IN r.;C~E THAN 10 SECONDS .. - NO IGNiTION - .:; MINIMUM FUEL ~ .. FLOW FOR RELlABl.E .. . .. IGNITION .. ., f/ • .. - ~ • .- ..; Z .. • - ~- -- 10 20 30 40 50 ENGINE SPEED - "'0 Tf82-5891 " i ~ur.. ,... Coc:bustor leve l"pment. 165 sition from the start to the main nozzle was accomplished manually on the rig without dif- ficulty at burner inlet temperatures from 800°F to 1100·'. CERAMIC COMPONENTS--The combustor shown in Figure 14 has :our ceramic components: the dome, the main body, the dilution band. and the pilot flame tube. After each day of test- ing. the combustor centerbody was removed and the interior Slurfaces visually inspectetroit Diesel Allison (DDA). Division c,f General Motors Corporation, has successfullv engine tested the ceramic gasifier turbine noz:!!!e and rotor ass(,mbly and the ceramic re- generator system to the maximum 2070°F-confi~ uration operating conditions. CERA'11 CS FOR ENG INES Pili CATE PROGRA!I wa~ the first of the three major DOE programs to develop structural cer- a:nic components ... ith the objective of signifi- cantly improvi"!t thE, fuel ,;onsumptiou in gas turbine engines. Ollie of the CATE Program goais was to evolve the proper ceramic compo- nent development approach that would lead to application of ceramic cOllllponents in a produc- t ion engine, the 00.1, GT !>04. Figure I is a representation of th.e CAn: program development approach. Tbe remainder of this paper pro- vides background for the program and discus- sion for the major disciplines s~wn in the chart. 167 S. R. Thl'lil$htw ~"o.t Dinel AlhSOfl. D.vislon C)f G.!netOl ""'tors Co To successfully lntroduce ,tructural oer- amics into the hostile ~as turbine engine ~n vironment. it is i:ldJC'iU<1t\..' !..J x'rel',' ~:-::J.:.h: ture components tor englne test. Secause.Jt the ~rittle nature of ,er3mics. additi~nal effort is required on the part of an eng,ne manufacturer when addressing the problem )! designing with ceramics. Th" "'ev t" :he "JC- c~ssful introducti0n .)f ,.:pramlC-; 3:1d :'he :~ velopment approach tairLttl~ .:'l')mpOn~.,ts ...,ithout ,~.a~aat~. The ,jevelopruent .)! .1 l'i~ful ..:'"~rall'll.":: -a.at~r: 1~ 15 jlr~ctl\" linfted :0 th~ t~~ine ::hat ...,~:: j~~ the "Ilat"ria 1. ~h.e jesign ..)f ..:~ramLC ~~(mIponent s tn .... 01·"~s the analysis ~ethods used; speclfics iUC~ 35 the ~ritlcal l~terface with metalliC surfaces, ,1c(:urate Cer3ml.C llat~ria.l ..:haractf"rlzatl,)n llta) ~ll-d~!lnl2'd ':..mIp0n~:lt ·~:lv~r')l"tm~nt<;. ~valuati0n ~i th~ analysts results. ~nd j~iln lag .p .. clficatlons :0r the ~aterial and C~ ?,-lnents. '1aterials d"velopment and desiolCn ef- forts Uliust proce.ed t0geth€'r and L()oslderabole coordiriation and iteration is required tor the successful llIlanuLicture of a c~¥onent ~h,H will satisfy deSign requlreQents. After complet Ion "f t~e je~ilt1li .. &t"r! 11' JevelopInpvnents from th0S~ 'Jorthy 0t ~"~ln~ eV'31u.ltl ... )n ... Juring th~ ?'['o0f tC';[: in.~~ an t?,V.llU.l( 10n ,)t :he ~anufacturln~ Droc~ss ~nd th~ J~sign ~on .=t·pt ~~ )~t,li,\ .. d .. '!"h~ fl;"lal Drvoi-of-concept \ lnd ~h~ ,)01,:, .1c.:~pt.lo1t:'! ·)n~: IS !"'ngine test- :'l~ ,)t :n~ ~~·,Jm\":- ':\.")Cipon~nts .. 7"h~ ::~5t ~ha:ie ~us'= !:50 'Hl l ~ ': : ~ "') ~ 'I i '''"nt") 11 S t r J: t -c l';:.pr --. .... t?<:. .: .. ..: ' .... t': :l':lt:!nrv ,~' ..:~r . .u:lJ,': .:..)r~'l:p .... )n~~nts ~v rl1S\:1~ ::.~~ .';~r~t:.'~ :~mp~ratIJr~ Ji the ~x :.:;: :':1)'; All J.S\.)t'l "~:- .. ,} ........... '/e-hl...:ular 5.15 ~urbl.n.e -!'1J<: 1.:h:". :-~I~ ;~r,)lI!r.lm :-),1,'; ')~t:·tl ~tHld~J '''' ~ ~~ \"':'1r:-:,' 1: ,~ :."h>r~·.· ~h.'( . ;"J~ 'f::\1..)t tv,,:' :- ...... '1- '''I ... )i.J~:-' ~v"·i .... )?:!I.It~nt :hVLS,l:J:1.. Jfii,.:o;' .,t :-!".].t1S·· ?,)rt~tl~n ~'rll~rAns. :-, ...... "lrl.l,lnJ.1. ~l.ln 'oo:&" :J apply .. ~~rdml.":~ l.:l.;r~"menta~l';t .It ,suc.:essl....:..::l'! :lli;.h"-·r ,)p'l!'rat'ln~ :~-np~ratur~~~. ~~~l!l.nla~ d1tn :QOOlF Jnd in- .:r~.J.Sl.'lg t~) 2J?'u.;r- ~nd; : 1:1,11 ~\f. t.) ':2t») 'F. ~v.tludt1.,-'1n ,:' :~'t" lnl.t1.1i .:~r..l::nl":- .::~p .. lnt"nt$ ..It 190v·F ~'as ~-t.~~n i'.l(:":'t"ss::.l} 1'>1 ,-·,x!lpl't .. t~~. fhlS ~"al'j.J.t L>...)O :':lC luJ~d 1.:11t ~-Jl .:~r,l.:tll"": ... H~rud i"'OC~SS jeve-l'>p"',ent, ~"rol\!HC '-Iatefl.ll ..:hdr ... ct~t'i ~!at 1,)rl .. :~r"'~lillC ":.JllClpont!nt Tl.i!. t~st ing. engin~, test ~t.lnd Jura!Hilty, ,,",j ,Wer- th~-ro .. d JE,~QOnstr"t ton In .. ~.lS turt)l~ i'0'-':' el.'ej tr:.ldt. ..\ sec'>'ld ,er&",i~ e-ngln~ .:,~nt l~ur atll,}n, to ~14;!" \.)O'n- : .lrrt:>'1t1·" .j~"lr~:~t.'iJ. :':11tl,]i ..:~~r,l~l': . -,mpl)nent :!r..)":~S$ :!~v~l,)pr.1~nt ,lnd :'..lbrl...:at 1.)tl il3ve Qe~fl =""'p\e-r",d, dnd an advanc"d pr.>.:ess .i.,.veiopment ·")(p~ri'"t1.t!nl is :\~.1rll~ ..:omplet il)n.. Extensive rig test inJit Jt tnt' 2070.JF-c0nf i~urat i0n C,?r- l"!'Il": .>)lllp0l'l~nts ~~ol:5 "e~n ": .. Jnduct~d • )~JA ~as ", .. 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'':I)J ~ t'i!,)ct I :lai.~eJ :~vf"10pment ~-,i :nt:" : l;J.lF-c.Hlt l,,:,·.::·lt l.H1 ·~"r..1:':1t..: :.-'l~;ll1m • ..lnJ :-·~jl!"~t..·: ... d :~.t-! :-"":'·'i1~r..lt..):- .J\:~ ~''::'~'; :) Lltl,Jr3- .:.r"l·~) '1.lS :'I .... ~t~n :J iev .... ~~)~) .l~j '''1'':':'"1~> j'·r.'/,)n- '::-l:t.~ ::It' ...:,-":'.j,!!~_: .:. )::l~h)!h.'·\::':~ : :- :.~ .. ~ .~ j" I)F- ""~lpn.}.51'" ''),.15 ·).·t'71 ·~:1~·.·.j '·1 :.lrl::J:~it ... ,~ :'~'r- 1~~3L': " 'ilD,"·h':1:" '·1 .- l"::'.\t:' : "'5t .. : j:l~l~ '?t:."r.Jt- :;11r;:.)r~:.1~ :'1e .H~l!:':h·-Jrlt~:l·>~j j~c.)ns~r..}- !~)n ,rt!: ··.'(.t ... ·l,.;l.Vt .. _ er...lml..: ..: _"W:j~Jn\.·:l~ :>r ''':~5$ h~v~ L.)p>rh:!Ot ~ ,: t:" r .1;ut..: ':1..lt t! r l..11 ~. "1. • .1 r,J( t ~ r l.!.a t i..>n ~ .... ':!;p ... ")n·:n.:. ;& •. )n.j~:...;: r'.1(":: l Ve ::'" ~;.\~...: t :.. )0. I nil :- 1. ~ 11.1.!ltt!..:.ltl,)n :~itl:)~. :-;,.~ :-t"il.la1.'~:16 actlvt- : ~."'j :)r ~hlS /0:".1:- .\ 1: t:"mph.l'ill!O!' ,-' ~pl~t'i,)n )1 ~:--:'t.~ ..:~t_\~l.,; '):.l.j~ :>rO~t,·q,j .!<::" ... .". ,Jpm~n .. t!x.- :h.·!'l~fn. :~!~ ~.)-)~ll.:!'t.· <":lI(!:1~ "'."1.''I.>.! ljt:'-J 1,:1 :~1.i •. H0(:".J.:'I1 .:.s the ~l!L'i...,n ·;r "'"J-6-~) :..,JGstrl.J.l ''';..3.$ :'It'''~::.: :.n~l.n\." •• n~..:h. 1:1 :'i l~:-n ... tal '':In- !l",:,ul'.ltl...>n. _)p't!'r .. t~; .it.l ~'.J.rt)l.1e ~nl~t t~m- r~Jt~n~r·atJ.v~ "':'.l'i ~.H~!.;;\~ Jl.t~, .1 :><.>w~r :r.lnst~r ,· ... st'l"1l!l ..: _Qbln1.:1~ :l1t~ l.i\'lnt )~t:."'i "l.,-!t~- '):"Id CY 76 77 78 79 80 81 82 83 84 I I I I \l I STUDY G. T. VANES SHROUD I REGENERATORS I I f BLADES &. PLENUM: V' VEHICLE DEMONSTRATIONS Tf82-576I Figure 2. CATE program schedule. two-shaft engines, and is shown in cutaway view in Figure 3. The 1900°F-configuration ceramic components were the gasifier nozzle vanes, gasifier tur- bine tip shroud, and regenerator disks with associateJ seals. These ceramic components h<.ve been successfully demonstrated at 1900°F rIT, while the 2070°F-configuration ceramic 20ffipOnents were designed utilizing the ceramic teChnology available to date. The gasifier nozzle support rings, vanes and turbine tip shroud, the gasifier turbine blades, and gasi- fier inlet plenum are ceramic to withstand the 2070°F-gas stream temperatures. rhe sequent ial introduct ion of components and materi~ls at successively more severe op- ~rating conditions is intended to utilize each "aterial full:, while permitting parallel de- velopment of the design methodology and fabri- ~ation processes peculiar to high-strength stru~t'Jrdl c~,rarnic .aterials technololY. 1~00°F-ESGINE CONFIGURATION Engine durability testing of the 1900°F- configuration ceramic components has been com- pleted, and the results are shown in Figure 4. The three ceramic components comprising the configuration were thoroughly rig qU:lt.l- :ied, and subsequent engine testing demon- strated the viability of the application of ceramic hard",.2re in gas turbine engines. Ii total of 7.475 engine test hours was accumu- lated, ... hich 'represents over 3]0,000 simulated vehicle miles.. Altho'Jgh most of this test ex- perience was (In a test stand oIPerating to a transient cycle representing a composite tr~ck duty cycle, the ceralilic gasifier turbine vanes 5nd regenerat (>:' systeoa vere de1llOnstrated in two truck installations featuring actual ve- hicle operation over highways, streets, and on 168 specially designed truck durability courses at the General Motors proving grounds. Through- out this testing, the ceramic part durability was excellent, underscoring the ability of ceramic materials to survive the violent en- vironment of a vehicular gas turbine engine. The reaction-bonded silicon carbide gasi- fier nozzle vanes were the primary components used for material process development for the 1900°F-configuration, an~ that processing was directly applied to the 2070°F-configuration, accommodating only geometrical differences. The results of these efforts and the initial development of (est rigs and procedures estab- lished guidelines for later application to ceramic components. The gasifier turbine tip shroud ring pro- vided an early evaluation of the design con- cepts for ceramic rings for the 2070°F-config- uration. The ring's structural requirements are moder.ate, but the abradable turbine tip shroud work ;hat was applied to this component has resulted in promising materials and con- cepts 'i",ed at addressing the problem of cer- aMic blade tips on ceramic rubbing surfaces. The regenerator disks for the 1900'F-c.~n figuration were of two types: thick wall (O.004)-in. thick) and thin wall (0.0035-in. thick) aluillina silicate--both rated at WOo'e (IB32°F) :.aximum temperature. The aerodvnamic perf o fllla n(:e of ~hese di.sks has been exee ilent throughout. the progralll\. In addition to the engine durability testing, laboratory testing has concentrated on establishing those feat- ures of the disk that lilllit the strength and life characteristics~ Oevelop1llent work con- tinues on this f&aily of co&positions to pro- vide a raal:erial suitable for the high-tempera- ture engine configurations. The total experience of these three ini- tial ceramic cOllflponents has demonstrated the structural. and che .. ical stability of the cer- Fi~ure 1. Ceramic c~on~nts installed in GX ~04/)05-4 engine. Vane Turbine Tip Shroud 0 RegeRsrator Material Reaction Bonded Silicon C.nbide Reaction Bonded Silicon Nitride Retel Silicon Carbide Reaction Bonded Silicon Carbide Sinlered Silicon Nitride lithium Alumina Silicate -------_ .. _-- Thick Wall 1000 0 C Alumina Silicate Thin Wall 1000 0 C Alumina Silicate Regenerator Inboard Seat RigTested Engine Test~l Hours HIgh Truck 1------+ ____ T_i~_, Part Instal~ 110 130 3138 1512 /' 67 81 81 435 435 -----+-_. __ ._--_ .. ---_._---- 4 1546 985 3 113 113 3 i 11 11 I ---1----.-.-----1 , I S I 2833 1808 16 I 3938 3050 - l3~ 7475 2160 .... Total 1900· F Cont;,gu.'lIbon 1475 Hrli. Veruc:te OplllafilOn: 6656 IIhlfi.lZ31 Hrs. I amic material c,andidates in an engine environ- OlIent. 2070·F-ENGINE OONFIGURATION The 20 70°F-,er.g ine conf igurat ion des ign features a totally ceramic gasifier turbine and regenerator system, which is required for incre~sing the TIT. The turbine flow path is comprised of 78 ceramic parts, including the 28 gasifier turbine nozzle vanes and the ~O gasifier turbine blades. All of the ceramic c~ponents have been fabricated by at least two, and in some cases as many as four, cer- amic suppliers, thus permitting the assessment of the candidate materials available and the potential component fabrication teChniques that have been developed within the ceramics industry. ~ith the exceptions of the gasifier plenum and the turbine tip shroud, all of the parts have been made with both silicon carbide and silicon nitride. Figure 5 shows a cross section of the hot section. In addition to the ceramic gasifier tur- bine, tvo noncel'alllc engine design features are required to permit operation of the 2070·F-configuration: (1) the relocation of the temperature sensor for the fuel control svstem from the gasifie'C turbine inlet to the power turbine exhaust to keep temperatures within the limits of ~omrnercially available thermocouples, ~nd (2) change in the engine block cooling. The resulting control uses mic rOf,rocessor techno logy replac ing the ana log controls of the baseline engine. TI,e design goal for the ceramic parts was based on a probability of survival consistent with failure modes and effects analyses and on competitive warranty costs in a commercial truck application. The cerami.c design metho- dology and material characterization. although changill.g with our understanding of the 2070'F- test experiences. were developed during the initial ?hase of the program and were applied :luring the design phase of the 2070·F-config- ~ratlon. The test results correlate with and ~ive credibility to the ceramic design metho- dology and material characterir.ation. Inlet Plenum .: ~~. 2& : .r- 111 The gasifier nozzle assembly is designed to isolate the vanes frOlll all mechanical load- ing by capturing them in slots through the in- ner and outE!r ceramic vane support rings. The ceramic rings are held in place by a metal strut and support assembly, which is shielded from the hoI: gas path by the ceramic strut shells. thE! inner and outer vane support rings and the gasifier turbine tip shroud ring are similar in'design to the 1900·F-configura- tion tip shroud. The ceramic gasifier tip shroud has an abradable layer requirement for cOOlpat ibil ity with ceramic blades. Forty in- d ividual cel:amic blades are attached to a meta 1 turbine disk by a single dovetail. Around the dovetail sh~lpe on each blade is a 0.007-in. thick compliant layer of L60S. The ceramic dovetail of the blade is coated with boron ni- tride to serve as a solid film lubricant and diffusion barrier. The 2070·F-engine configuration has com- pleted extensive rig testing, and the rotor and nozzle assemblies have been successfully subjected to engine test ing at 2070° f-operat-· i ng cond it ions. The ceramic component des ign technology developed during the CATE program is supported by the ceramic component test re- sults and i'l being applied in other programs, such as the AG~ 100. CERA,'! I C CUMPUNENT t:NG 1:11:: fEST ;:XPt:~ I ~:SU:: The exp"rience of running ceramic compo- nents in engines has establ ished the feasibil- ity of common use of structural ceramic compo- Clents. The incremental appl ieat ion)r cerami-: components with a corre,;ponding increase tn "06 ioe openlt ing temperature has provided ,1 sound technology ~ase for the follow-cn cer- amic configurations. The first step was the introduc!ion of the 1900"F-configuration cer- 3mic ~~nponentSt which included ~eramic ~3S1- fi~r turbine vanes, ~3sifier tllrbin-.:' tip ihr011d~ and re~enerator syst~m. Ait~r rl~ ~unning of the ~eramic regeneracc)r s\'st~m anJ !10zz1~ van~s. engine j~monstrat tons 'Jt!'r~ '::00- .lucted. Included in the "ngine test hours ~~h)Wn ~n FiglJ'rt~ ') tor the lQOO.)F-c0nt l~urat t.)!l -' Nozzle-Shroud .. ~AssembIY 40 ' .' ~Rotor Blades HOURS ~- CONFIGURATION VANES (VANE ASS'V) TIP SHROUD REGENERATOR DISK BLADES ENGINE Figure 1,. Ceramic are two vehicle demonstrations with the ceram- ic components. The engine was installed in a truck that \las subjected to severe duty cycle and operational testing, and the ceramic com- ponents withstood the severe vibrational and thermal sho.:k loading without damage. The second step in the incremental appli- cation 0f c'~ramic components is the 2070°F- configuration, which features a ceramic vane assembly (instead of ceramic V3nes in a metal assembly), ceramic gasifier turbine blades and tip shroud, a~d an uprated ceramic regenerator system. Extensive rig testing of all the 2<)7u'F-ceramic components ho's been conducted, lua 1 i f:-o ing part s for the eng ine test ing show~ i" Figure.,. The 2070·F-configuration is the iirst introduction 0f a rotating ceramic com- ?)nent in the CATE program. The complete cer- amic ~asifier section, ~ncluding all nozzle .: )\npon~nts ,lod th~ ":t!'ramlC ~)lades, has '::>een .,multane0u.lv engine jemonstrated at :070'f- ,)Dt:"rat In;: .;'ond it i0ns .. :-h~ ~0t:al ~x.pt'ri~nce ,.)f th~s~ ..:eranli..:: ..:om- ponent. ~a •• erv~d to ~oi.ter the promise of .:~ramL~S 3:; a ~lable material for a ~a9 tur- ~i.n~ ~n.~1.;1e4 Anal¥t,~al and ~xperi~ental test results ~n :~raml.C ~lad~~ nave Ldentifipd the ~~ed to l:uprvv~'" th,~ ... "Ive-rat 1 str~ngth ()f th~ bt..J.d~. ",h,eh \oItll als.) l:l'lpr~>ve reliablltt~·. The ap- ?arent w~akness in the blade stalk and the ~I~ld from the in'[lal p,~ces. jevel~pQent jeflllltlc'n 51~naled [h" need t.>r second "ener- atlon process jevelopmen[ d1C[,VltV. Th" ~b jective Jt .uch process jevelopment is to pro- vi:ie a !>etter understanding "i the 'nfluenc~ processing variables have on strength. as well .15 to jeilne tho!' .;ootrol n"cessar:-o to reduce variat>ilit;t for each phase "t the procesSlllg. A blade satrix process jev"lo~llt experi .. ..,nt .,as i,Ilitiated by :>DA .lnd C~lrborundum Co. (ClIO) 1900°F 2070°F TOTAL -- 3400 894 4300 1670 894 2564 1814 1578 9392 14 14 9392 Tf81-576-4 component test times. to satisfy this objective and is nearing com- pletion (see Figure 7). The I08trix experiment is a two-level fac- torial experiment featuring 13 processing var- iables, whir.h involve compounding, molding, sintering, machining, and heat treatment. Thirty-two combinations of the 13 variables have been used to produce ~800 blade/bar pairs. The experiment is designed to isolate the most influential variables that will ultimately be chosen to maximize blade strength and process- ing :-oield. These parts have been inspected at ~ach processing step by C80 and have been complete- I)' characterized by DDA. l.aborator.·y charac- terization of these parts has provided infor- 'Ration on defects, modulus of rupture (~OR) strengths l from both blades and comparison 'lars), process vlc11 data. eoollponent m'cro- strucr.ure, densities, and heat treatment. The lab<)ratory evaluations emplo:-oed jeverai ,",volv- i ng nondest ruc t i ve eva I uat ion \ NDE) t e~ tin i que s such .1S C-Scao 1 sonic v~lo<: itv, 3nd. ?nllC,)a- ';QUstIC spectroscop:-o. Sine of the 32 ~xperl ~~nts have been selected for ~pin testt~~. !he laboratory characterlzat,on ~ill ~~ ~"m !:>ined ..,ith spin test results in the ~ ''1.11 13ta ~Y31~ation dod ~0rreldti0n. A '::()C!;lput~rlz~d ,Lila o! .... a.i.U..1tl..)n .s -!t"sL,n~J to provide cl~plet~ ~haracterization ~i ~ach )t the steps in the 'IIan":acturl"" process .In.i correlation with !>oth SDf. results .. "d .. nd :>1'0- duct performance. th,,: inal r"sult "" d ,,~ • !>4!-tt"r understanding of :he proce,sin.t ,'arl- ablest sensitivlti.es ~n.j .J j~iinic~('In l! t"'t:" control n~cessatV for e .. eh phase or :h .. :rltl- cal ceramlC ?r()-C~$Sln..g. t:llSTllH~NTED SOl.ZLt: ASSEl18LY rh~ jeslgn 3D41YS1S ~$"d :ar t~" _"ra~l: ".>azl" cOt local neat trans- fer coefficients for the ceramic rings. d ;"i:>nltation regarding the effects of liq- ~,d and vaporized fuel during starts, ac- '~lerations. Jecelerati0ns. and shutdowns. These data were obtatned for both rig and ~ngine environments. and the resulting modtfi- cations were re-evaluated in the engine. which confirmed th,> ant ic i~.ated correct ions. The tJs : .) Second" " cool ing air flowing ,)vel' the .)utt!'f" ':i~r,lr..1ic rings caused excessive ra- ..]1.41 t~ap,eraturt! ~r .. dients in th~ rings .. ,) !iighe.- th.~n antic1pated :.xal heat trans- :,.r c~ificl('nts .. xist around the )ut~I' .:~ra.~\c rings. :'e a;,age ,) f coo Ill'l& all' under th.. ,nn"'r :~r~ic ring _aU$('o ('£c('ssiY@ radial t .... p"'rat\lr .. ~r"di('nts 1n the l'Ulg • .) So adver." .. £fects frOOlII fuel <>1' circu.efer- .. ~t1al t('~~ .. rature ~ra4ient' wer .. 1denti- tl~d .. TE82-5765 Ceramic blade status. 113 The following modifications were incorpor- ated and tested in the engine with the instru- mented nozzle: o The secondary cooling air was redirected to eliminate contact with ceramic compo- nents. o Leakage under the inner ring was e~iminat ed with the addition of seals. In addition to ~ifying hardware, design analysis inputs were updated to include the higher heat transfer coefficients and measured enllirol'llltental conditions. This update result- ed in analytical predictions of the previous failures encountered in the shock rig testing, plus predictions of success ",ith the ftlodified hardware, "hich was demonstrated with subse- quent successful rig proof tests to 2070°F- conditions .. The utiiization of the instrumented nozzle assembly p s<,d \ n ~ he en TE progr",Ill. 7Jithout good correht ion between an- alytical predictions and test results. the je- sign _tho'LOGY TE82-5766 \>igure 8. Thermal shock rig and engine testing. 2010°F CONFIGURATION 20100 f ENGINE DEMONSTRATION • 2106°F AVG. BOT • 2070°F AVG. RIT • 4 COLD STARTS • 342 HP FROM CERAMIC BLADES RESULTS • SUCCESSfUL OPERATION CIt NO VISltBlLE DISTRESS .. SUBSEQUENT DURABILITY TEST FAILURE TI,82-5767 Figure~. 2070" engine ~onfiguration. plete 2070·F-configuration, excluding the cer- &~lic plenual, ",hich has been e 1 i_inated frOlll the project due to funding limitatlons. Also included in tbe engine ",ere tbe ;070'F-config- uration cer&mic regenerator disks and seal system. The cera.ic nozzle coaponents were reac- tlon-bondi!od silicon carbide ",ith the exception of seven vanes and tbe outer vane support ring, ",bich were sintered alpna silicon carbide, all s~plied by CBO. The vane retaining ri~g and three of the strut sb~lls were Refel silicon carbide supplied by Pure Carbon Co. The re- maining strut sbell was slip cast alpha sili- con carbide by CBO. All 40 ceramic turbine blades were sin- tered alpha silicon carbide supplied by CBO. The alumina silicate regenerator disks were supplied by Corning Glass Works. The testing conducted was a two-phase program. The first phase was the successful demonstration of the 2070·F-conf igurat ion at maxi'Qum rated operat- ing conditions, 36,905 rpm and 2070·F rotor inlet temperature (RIT). This is equivalent to 2106·F burner outlet temperature (BOT), which is cooled to 2070·F by secondary cooling air that enters the flow path ahead of the turbine rotor. During this first phase, two cold engine starts were made, an':. operat ion over the speed range from idle to 100% speed was accomplished while data were obtained. At the rated 2070·F RIT operating condition, the ceramic bladed gasifier turbine produced 342 hp. Post test inspection with a borescope revealed that all the ceramic compo- nents were in e~cellent condition. The second phase of the test program was durability orie,nted. The objective was to ac- cumulate appro~:imately 50 hr operation at 2070·F RIT and 100% speed. Two cold engine starts were completed during this phase, but a failure occurred at 35,800 rpm (97% speed) during an accel.eration. The failure resulted in extensive dy ceramic blade spin test results, which is the topic for the next chart. Corrections have been incorporated for the next engine test to prevent reOCCUl~rence of these fai lure modes. SPlS TEST tNVESTIGATION--CERA:'IlC 5LADE tMPACT DA."IAGE As part of the engine ceramiC ~laded rotor failure investi~ati0nl 3 spin test program was :c)nducted to evaluate the possibility of blade ai"foil failuI'<' resulting from impact with ob- j "" t s ori 1: inat ing in the eng; n., upst ream of the rotor (see Figure 10). Two potential failure ""odes "ere identified .during the en- >;ioe failure investigation. The first in- volved several pieces of moldable Fibol ing-a IT supply to establ ish the test c,·cle. The t il"le/temperature .lccel r.lmp. cvclic peak temperature. and decel ramp ~an be- ..ljJust~d t!.-') -nat~h ~n.gl.ne regeneratur inl~t ':"clie conditions. Laboratory :ind engine testing has clearly established this cyClic thermal exposure as ~ore damaging than st~ady-state operations. The engine cycle selected for simulation In the laboratory test was full-power accel Ir.,,,, ~tabilized idle (corresponding to .. bout lOOO'F-l050·F) to the selected cycle peak ~as t~perature. followed by i~ediate jecel to Idle. The tests have been ~onducted on the 1IOO·C (201Z"F) alw=ina-silicate ~3triK at three ?Cak t~perature levels: 19)O·~. ~O)O"F. and ;l,O°F \vhich includes the s4Kiaum t~per ature anticipated for the ~26)·F-configura tlon). Folloving th .. ,e rlll cyclic therwaal ex- FIBERFRAX INSULATION o J LJ LJ ~1I5~1~~ ~ IMPACT WITH TE~"T BLADE AT 35,800 RP~1t SEGMENT OF CERAMIC RING / L/ /' ''-..;----- IMPACT AT 35,800 RPM IENGINE ROTOR RESULTING AIRFOIL FAIWRE (3X) ENGINE R01"OR RESUll'lNG An~FOll FACLURE f'igure 10. Ceramic blade imp.lct damage tests. posure tests. the matrix core sample was cut into test bars tor tangential ~OR testing. The ~IOR data in rigure II illustrate the effect o,f increasing peak teool'erollture on disk life. The duty cycle rellresented involved a 70.000-1b gvw t:ruck. which makes S.S accelec- ations from idle to max power every hr. Auto- mot i ve alpP Heat ions ",i 11 inc rease t he number of accel/hr to approximately 30. which ",ill expose the regenerator tC) the peak tempera- tures at a much faster rate. thereby signifi- cant ly reduc ing the useful li fe of ~'" 'egen- erator disk. The data shown indicate that for • peak temperature of 2150·'. the current re- generator disk matrix under the truck duty cycle ",ill degrade to thEI .ini_ acceptable strength level in about J.8oo hr. For an auto- 11'6 motive cycle. this degradation would occur in just over 300 hr. The cyc lie . thet'1otal exposu:-e rest illg wi 11 continue to accumulate data at the 2150·' peak temperature. Additional testing at 2250°' peak tem~erature has been initiated to further de- fine the c.apability and liOlit" of the llOOGe '''''trix ..... terial. The data presented do not take into account tbe effect of road salts 011 ral'ltrix strenst.h or that of stt-eslles caused by mecbanical drive systera and aerodynamic loads. The results of this ",ork clearly establish the ~d for a legellerator _trix _terial with .. teaperature capability above the present llOO·C _terial. Though the 1100·C aluaina- silicate is quite acceptable for engines ",ith peak regenerator inlet teaperatures below REGENERATOR DISK FIVE RADIAL lOCATIONS 12.10.8.6.4. IN. )00, \ TAUtK 0Ul"V C'l'Cl£ $ 5 oIICC£LE'U,TlOHSo PE ... M()UIR ~ 400 ICO t 200 teoo JOOO 'IlHtCU ()rP(tRA nON ~ ttOURS LABORATORY SCALE TESTING CYCUC THERMAL EXPOSURE lCTEI SIMULATES • ENGINE ACCEL TEMP PEAKS (I) THERMAL GRADIENTS THRU DISKS TEST SP£CIMENS FROM DISKS HOT FACE ; TEST RESULTS MORE DAMAGING THAN STEADY STATE AXIAL VARIATIONS IN STRENGTH 40% LOSS IN ttOT FACE STRENGTH SIM!LAR RESUI:rS- ENGINE CORES '- COLD FACE SAMPLE TEST HOT FACE BAR LOCATIONS lEB2-5769 Figure 11. Regenerator material testing. 2050°F, and also permits engine development testing at pe;lk inlet temperatures up to 2lS0°F, the life will be unacceptable above ~l50°F. CONCLUSIONS AND REC(lNMENDArrONS The CATE program will be concluded at tne end of calend,~r year 1982. CATE was the first of three 'DOE ceramic programs and has lead the 1. PROGFlJ,MS SHOULD DEVELOP CERAMIC COMPONENTS FOR ENGINES til TRANSITION FROM OPTIMIZED lEST BAR PROPERTIES TO USHUI. COMPONENTS NOT VET POSSIBLE, () ENGINE ENVIRONMENT DICTATI:S REQUIRED CERAMIC lAATERHAL PROPERTIES. ~ CERAMIC MATERIAL DEVELOPMENT MUST BE BIl5£D ON ENGlf1!:'OEFINED REQUIREMENTS 2. CEAAPJHC CO~'1PONENT DEMONSTRATION REQUIREMENTS CI Pl'tOOF Tt:ST RIGS ARE REQUIRED TO ELIMINATE FLAWED COOJlPO~IENTS, Cl TEST RIIGS MUST APf'iI'O)(trMWE ENGINE ENVIROOUENT, • T£STRfiG ENVIAON~ENT MUST BE COMPLETELY OI!FINED AND UNDERSTOOD TO CONDUCT SUCCESSFUL otVEl(~i>MENT TESTING. e PIlOOF leST RIGS WHICH CQMPUTELY OUPUCATlE ENGIIIII! ENVIAOI'iMENT CAN BECOME VERY EXPENSIVE, • COST EfFECTIVENESS or COI/!Pl£X RIGS VERSUS ENGIHIE rESTlMG MUST BE STUtDlIED. 4) ENGlI4I: reSTING IS TNE ONLY OEMONST1IIITQfi OF CEMMIe CO~ENT ACCEPTABILITY way for development of ceramic materials and component technologies. Although funding con- straints I'educed the ,.,ork scope of the original project. th~ CATE program still enjoyed great success. It is appropriate nov to reflect on the accomp:ishments of the program, to draw con- clusions, dnd to .ake recommendations that will enhance the remaining DOE programs and future cet'amic deve lopment effort s. Figure 12 3. MANUFACTURING PROCESSES AND NOE TECHNIQUES REOUIRE IMPROVEMENTS o MANUFACTURING PROCESS DEVELOPMENT PROBLEMS " EXCESSIVE VARIABILITY POOR'REPEATABIUTY 211NCIREASED UNDERSTANO'NG OF VARIABLES 31 INCREA~O NOE CAPABI~ITY 4i AVAILABle Not: TECHNIOUES tNONDESTRUCTlVE EVAl.UATlON' 11 SUAll flAW DETECTION REau\Hc~ 400ITlONAl OEVlELOI'ATENT RlGh 1S IS A IiIA.IOR CONCERN, Tf82-5770 Figure 12. CATE prograa: conclusions alld rec~ndations. 171 present!, these conclusi.ons and recOlllmendations, which .ne amplified by the following discus- sions. 1. Ceramic cor.>ponents, specifically de- si~ned I~r an engine with precise material ;>r)pertl.es required for that "ngine, provide the means to develop and deruonstrate useful t~chnoIJ~y. ~aterial for structural appllca- tlans cannot be successfully developed using onlv [",,,t bars; high-strength test bars alone cann~t demonstrate cost-effective producibility 0~ structural integrity in an engine. ~he ~oal f~r all ceramic c~mponent testing ih0uLj ·)e to Jeml)nstrat~ (~ramics in ~n ~ngine ')perat ing to its dutf ~yc Ie. To conduct cost- t?ffective engin~ testing, ceramic ':vmponents ~~~-;elected f~r use that have an accept- able ?r.bability Jf survival. Available in- spection techniques are inadequate, so proof testin~ in rils is required to eliminate the unacc~pl:able components. Rig testing also pr.:Jvid~:; .1 mt:'ans to learn from failures. Be- cause the evidence is not destroyed, it can tie 'Jsed to (ldvance th., 'Jnderstanding vf brittle material failure mechanisms and [0 develop de- sign :nethodology and no"destructive (NOE) In- spection techniques. , ~igs :nust have completely jeflned and ·Jnderstood environments, and they must approx- ~·nat..,. ~ht::' o:"'~ine to) thr .:>xt .... nt that appropri,1te ::-h!nal stress lS j~vtl'10po:'j In tht- t~:st parts. 118 However, rigs that completely duplicate engine environments can be extremely complex and ex- pensive, and are not cost effective when com- pared with engine test cost. A properly de- signed rig is critical to successful ceramic component development, but it cannot be con- sidered as t:le ultimate demonstration of ac- ceptabi I ity. Only successful engine test in~ to the appropriate duty cycle can be consid- ered a demonstration of ceramic component ac- ceptabi 1 ity. 3. The successful development of NDE techniques and :IIanufacturing processes can only be accomplished on ceramic components thac can be engine tested and should be a sig- nificant part of a ceramic program. The CATE program has clearly demonstrated the require- ments for reduci~g variability in manufactur- ing processes and for developing NDE tech- niques that discover very small flaws in a cost-effective way. 4. Ceramic suppliers and engine manufac- turers must continue their multimillion dollar effort in labor, facilities, and cost sharing if viable competitive structural ceramics are to be developed. And the Government should continue to be a partner in this effort. Fur- thermore, these suppliers have a right to ex- pect a fair return on investment and a protec- tion of patent rights that may have commercial use. (:ERAMIC l'~I:CHNOL()GY SESSION --- .-- -- --:- ~--- Development of Ceramic Components for Gas Turbine Engines ABSTRACT ~-' ! Ceramic component actlvlty '.mder CATE and AGT 100 programs has rocused on the development of material strength characteristics in full- scale hardware. Emphasi~ has been directed toward net-shape processing of silicon carbide components (most notably blades and rotors). Selected components have also been produced from a variety of si 1 icon-·based and zirconia materials. StatP-of-the-art processing and strength characteristics have been realized in the 2070°F-configuration GATE turbine blades. To further improve these properties, a develop- lUent study is current i.y being conducted with Carborundum (CBO). In addition, processing mc~thodology for structurally sound AGT 100 gasifier rotors has been established. Full- scale rotors can now be produced with cold- spin capability consistently greater than 100% design speed. Additional studies are currently in progress. Extensive development activities focusing on applicable fixturing and joining rechnology required for the c,)mplee< ACT 100 gasifier s,' roll assembly are also proceeding. , -----' 2070°F-CONFICURATWN CERM1!C aLADE DEVELOPMEtJT THE CERA.'1IC ROTOR BLADE was identified as the :nost c rit ical st ructul'al component in' the GATE turbine flow path and has, therefore, been the subject "f e~tensive development act ivities. During 1979- 1980, the first process develop- ment program addressing the fabrication of in- jection-molde,d 2070°F-configuration blades from alpha silicom carbide was conducted at COO. The focus of ~his early activity was to estab~ lish injection molding parameters conducive to the highest yields of defect-free blades. Upon completion of the program in late 1980, a com- plete process routing was established for fab- rication of blades. Subsequently, a large "produc t ion" run of 641 blades was undertaken to quantitatively assess blad.~ fabrication capability. Process yield, structural/dimen- 181 Lance E. Groseclose, P01er W. Heitman, and Jenn Chang D'ltroit Diesel Allison. Division of General Motors Corp. sional quality, and strength characteristics were evaluated. Figure I summarizes the re- sults of this endeavor. The total process yield of fully machined blades meeting both s~ructural (NDE) and di- mensional requirements was 28~. This was thought to be an acceptable level for this stage of the process development. Initially, qualification test material molded simultaneously with each blade was evaluated to assess indirectly blade strength characteristics. Various surfac, finish con- ditions pertinent to the finished blades (longitudinally ground, as-fired, and trans- versely ground) were examined. Soth the as- fired and transversel.y ground materials wet'e oxidized for 24 hr in air at 2282°F. (Note: Previous experience has shown that such a treatment will restore strengths to a level cM TE82-6111 Figure 2. Blade spin tes results. 182 separate processing variables imvolving com- pounding, IIIOld ing , sintering, sachining, and heat treat_nt. Thirty-two sepaxate process- ing schedules are used. The prxessing vari- ables addressed in this experiment are those thought to be associated with tbe strength- controlling defects typically observed in the blades evaluated to date: spherical pore s, large crystals, and machining flaws. Consid- eration was also given to variables pertaining to microstructure, particularly near the sur- face of the stalk. Figure 3 illustrates the cbaracterizati~n procedures to be performed in tbe evaluation of each separate blade recipe. The shaded areas represent operations cur~tly in prog- ress. All other operations have been complet- ed. All 4800 blade/bar pairs have been made at CSO, with inspection& after each processing step. Laboratory characterization of these parts is completed, inc luding Illic rostruc tu ra 1 evaluations, HOR strengths obtained from both blades and companion bars, and ~ characteri- zations (ultrasonic C-scan, ultrasonic velo- city, and photoacoustic spectroscopy). Nine of the thirty-two recipes have been selected for spin testing and are currently undergoing final machining. Correlation of these spin test results with laboratory data will then be made to define the sensitivities of the processing variables and ~o provide in- formation pertaining to the processing contrvl necessary for the fabrication of consistent, high-quality, high-strength blades. In addi- tion, recon®endations for further fine tuning of the process will be made. Slade strength characteristics are to be evaluated using both companion test bars and miniature test bars cut from the blades. I.n addition, a sample of 10 blades from selected processing recipes will be subjected to an overspeed to failure spin test to further de- termine blade performance. A summary of the type of strength data generated in this pro- cessing study for one of the 32 individual re- cipes follows. The companion test bars were molded simul- taneously with the blades following an identi- cal processing schedule. Three :siniat:ure test bars, _asuring 1/1.6 in. x 1/8 in. x I in., wer.e ultrasonically m"'''ined froa the attach- ment/stalk region of ,>". 't of 12 ·:olades. Both sets of material wer" "repared with three tYr~.s ,"f surface finish: 10ngitt.: .. ::iinall~: ground, as-fired/oxidized, and transversely ground/oxidized. These surface condi- tions were selected to be representative of those surfaces present in the finish machined blades. 'fOO average 1"Oom temperature !'tOR "f the as-fired/ oxidized companion test ~aterial me~sured 70.41 kai. This compares well vith the strength of similar material cut from t'te blade(> of 95.03 ksi, when appropriate torrec- tions for specimen size and loading factor in the Ileibull statistical model are taken into account. Identical strength-controlling ~-~ ..,..--- ---.. ~ ::"~ ---'-~~ '.. I , ,~ .•. , ...... "'" I L ___ ------' I-~ i ~ ... iIt..'{! i ~~ • '" --:-.-.:.<"~ .. -<~-. 100 Blade/Bar Pairs -, I I I ,~'"::::.;,. JI "", .. " ....... Q, .. ~ .. , """. ~ .. , <,,,. ........ ~~ CORA""'} RESultS .. -.-- - snECT OOPtdtOU ""C_ .'["N"H G @~ tlIACH.tN£ l'1li01 '£61' BLADES { VALUAtE RESUltS ""N' .. 5&>"Q SPUD tA\lEFtAGf) • , STALK fAIlURES TE82-5901A cae tur i a 1 ;>rucess ing mat rix ac t i vi ties. flaws--surface and internal pores--were ob- served in ~th sets of material. However. the stn!ngths uf both the longi- tudinallv "round and transverselv ground/oxi- dized :!iaterial:s 'cut from the :'lades were sig- nific:::ntlv lower than anticipated from corres- pondin~ 20mpanion test material. although sim- i lar tvpes of 3trength-controlling flaws were identified. This would seem to indicate that the frequency of defects f"und in the interior of the blades fabricated from this processing recipe is ~reater than that 0bserved in the .:ompanlon test "TIat€'riai. In 1950 a deve 10pment program with GTI<: Laboratories was initiated to establish pro- cessing parameters for the fabric at ion 0f in- jection-~olded 2070"F-configuratirn turbine :'lades :roo sintered silicon nitride contain- ing 6% Yi)3 and 21; "H203' The primary objec- t ive of this prograra was to produce th,- highest \field of defect-free blades that would meet ":imensional requirements. This effort focused on the injection molding segment of the, blade ;:n"ocessing sequence, with particular emphasis ;>lac'!d 0n the mixing, molding, and binder re- "oval steps. Upon cOOlpl'etion of the development study, a detailed pr~:ess ~uting (designated AY6-40l.) WaS established, and 32 blades were fabricated for laboratorv and spin test evaluation. The 183 10 best blades were finish-machined and sub- jected to a room temperature overspeed to failure spin test to characterize actual com- ponent performance. The results of this test- ing are shown in Figure 4. The average fai.l- ure speed measured 48,730 rpm, equivalent to 132Z of design speed. The primary strength- controlling defects observed in these blades were shell-type surface flaws, which are not tvpical of the failure origins generally found in this material. These flaws were identified as the result of an abrasive cleaning operation performed on the blades after sintering • To further evaluate actual blade strength characteristics, test bars measuring 1/8 in. x [/16 in. x 1 in. were machined from the remain- ing dovetails of the failed blades. Three- point MOR testing of I:>an. cut from the base of the dovetai 1, where the surface cond it ion was identical to that tor the most highly stressed region of the dovetail, revealed an average fracture strength of 99.70 ksi. Thus, while spin test perfornmnce to date is considered exce llent, further improvement is expec ted. Additia·nal test bars were cut from the midsection (interior) of the dovetail. These bars ,were tested with a longitudinally ground surface condition, alld an average strength of 70.3'> ksi. was measured. Surface low-densit)· regions aoo pores _r.e identified as the pri- lIlary strength-controlling flaws. The signifi- cant decrease in strength noted in the interior of the blades compared with that obtained from 99.9r---~-----':"'-"-----------r--" '~'G. FAILURE, SPEED: 48.730 RPM i 900~ ., 700t- 500~ i • ,()()O" SPeED I.IJ 200'" cz: ::l ..J ~ laO,.. ... >- .. z .... 50-U cz: w .. 3 Or 2 o· , o· '3Ol~'_---3~5~-~--4~0~----4~5~'---50'~---}55 FAILURE SPEED - KRPM TE82-6112 Figure 4. GTE Si)N4 blade spin test summary. the surface indicated that additional develop- ment activities were required to enhance blade uni.formity. To addre,;s the difficulties encountered wi th interna 1 lou-dens ity reg ions previous ly observed in Ifirst-generation injection-·molded silicon nitride blades, additional process de- velopment studies were conducted by GTE I.abor- atories. An updated process specification (AY6-40S) ua,; developed, which incorporated a modified binder systelll with i,nproved binder burnout characteristics. Evaluation of test material fabricated by this process specification is currently pro- ceeding, with encouraging results. The aver- age room temperature MOR of longitudinally ground test tRaterial is 89.49 ksi, while the average as-fired strength is 78.72 ksi. These values repre!lent the highest strengths obtained to da.te for .Iny GTE injection-molded Si)N4 material. One hundlred-eighty blades to be produced from this nell process routing are currently on order, with an anticipated delivery date in fiscal year 1982. A preliminary sample of thl'ee blades was received for dimensional evaluat ion. The dimensional stabi lity of these blades vas excellent. with all dimen- sions found to be within design specifications. CERAMIC ABRAI}ABLK SEAL DEVELOPMENT The turbine tip :Jhroud shovu in Figure 5 was fabricat,~ from reaction-bonded silicon 184 CARBORUNDUM RS SIC SHROUD ABRADABlE COATING: 86% ECCOSPHERES 14% YTTRIA-STABIUZED ZIRCONIA TE82-6113 Figure S. Turbine tip shroud with abradable coating. carbide by tt~ Alpha Silicon Carbide Division of CBO. This component was produced by green machining a compression molded ring to near net shape. Following siliconization, the critical dimensions were finish ~round. To allow for tighter turbine blade tip clearances, a DDA-developed abradable seal material was applied to the insidr diameter of the shroud by p la9ma spraying. This abradable material contains equal weight percentages of prestabilized zirconia (with 8% yttria) and Type FA-A Eccospheres (hollol. alUlllino-silicat" spheres). In 1980-81 this composition, applied on a metal shroud, successfully ran for 288 hI' at 1900°F condi- tions in CATE engine C-l. This particular ceramic shroud ring has been qualified at 2070"F conditions in the thermal shock rig and is planned to be installed in the next CATE eng ine bui ld. The abradability of the zirconia-Eccosphere ~ystem has been evaluated in an intentionll rub situation on the abradability test rig. Using Ii ellO sintered atlphli silicon carbide blade. t~ice proof tested to 43,000 rpm (117% design speed). a rub depth of 0.005 in. vas achieved with no distress to either the hlade or the shroud. The abradability de.onstrated for this material system is considered suitable for en- gine applications. CERAI'IIC ROTOR OE:VELOPMENT--PROTOTYPE '''ork continued during fiscal year 1982 at CSO on the def illit ion of processing parameters for the producti.on of injection41101ded sintered alpha silicon carbide AGT 100 gasifier rotors. A limited proce,lsing matrix was designed and conducted to establish the process pa~ameters necessary for the fabrication of high-strength prototype rotors. Variables addressed in this study included binder composition, :'inder re- moval technique, and sintering procedures. The characterizat ion of the protatype ro- tors received 15 " result of this effort has been completed. The rOom temperature spin test to failure has proved to be a useful tool in evaluating rotor performance. Figure" pro- viJ~s a .ummary of this testing for the latest 15 rotors. Of these rotor., 14 achieved ourst speeds in exce~s of the 100Z mark. The appli- cation of 'oIeibull statistics in conjunction with finite el€,ment analysis .enabled equivalent four-point )fOR st rengths to be inferred frOID these results. The ~edian burot speed of 97,000 rpm converts t) an equiva lent standard bar strength of 4Y.' ~si. Test material cut from actual pratotypc rotors was also evaluated. The average ~OR of 48.7 ksi measured for bars cut in the radial direction frO"1 the backface of the rotors cor- relates \Jell with the predict"d strength men- tioned above .. Y.ow~ver, rnatertal cut tr0m the intel-ior of the rotors in the axial direction possessed an average strength of only 29.5 ksi. UJ 0::: :) -.1 e radial dtrection reg.- stered an average strength of 55.32 ksi. An average strength of 51.33 ksi vas observed for bars cut in the axial direction near the exdu- cer. This represents a significant increase over the 29.5 ksi observed for the s3me region in the prototype rotors. Only a single low- strength b.n (No. 13) with a defect similar to those prevalent in the hub t~gion 0& the pro- totype configuration rotors was encountered. The frequency of these defects in the engine configuration rotors, therefore, appears to be greatly reduced. Additional process develop' Glent activity will concentrate on the complete elimination 0f such flaws. SILICON N11RIDE ROTOR DEVELOPMENT GTE Laboratories has made significant pro- gress toward developing the technology neces- sary for fa.brlc 3t ion of an injec t ion-mo Ided sintered silicon nitride (6% Y203, 2% A1203) gas i f ier ro'tor. This development effort, funded directly by DDA, has involved the eVefore dimensiolHllly acceptable components c:ould be obtained. A nonstandard bi,GQdd grain size stollrting powder is employed. This lIIateril.~1 system has a 101>1 shrinkage factor so that critical dimensions can 00 obtained without finish ~chining. Th~ pilot tube and dilution M,les are, however" ultrasonically machined after sintering. The slip cast coer- bustor body lIulteria 1 holls a coarse-grained \!Ii- crostruCtUI1l vith a relativE!ly unifortll average grain size of 6.0 microns. The apparent poco- 188 SLIP CAST TEB2-6116 ~igure 8. AGT 100 ~ombust"r asselublv. sity is approximately 10%. Despite this ?oro- sity level, test material slip cast simultane- 0usly with the body registers strengths 3?- proaching those obtained from either dense i.opressed or in]ection-molJed .intereJ -,_ ",ateria!. Bars with a 101l'lit:Jdinallv ~round surface condition display an average room tem- perature ~R of 51.79 ksi, while the average str~n~th 0f as-fired sp~ci~ens ~e_l~ur~s ~S.:~ ksi. The primary strength-contrail ing flaws ->bserved in both cases were sma II pores. The as-f ired st rength represents a subst ant ia 1 c:u- provemeot over the 32 ksi previously rec0rd .. d for earlier slip :ast material. The elimina- tion of surface blisters and ~ore agglomerate. thruugh !"lOdificat ions in ~asting proceduI'e {found to be the "rimary failure ,>ri~ins in the early '!Iaterial) resulted in this 5trenJot~" i:uprovement. Both ri;; and ""gine .)pera~ ing ~xperieoce with the ~J~bu.tjr assemblv has :,een e:~t"",p. 1. .... af- fi..xt .. j :.~ :'1t' :;.:r':: ~:11t,.t. ?rJ.1'.L'~,j :' Ll~t·. ....:1 .... t' : :h.· ~.·:lcr:i: : .... 1rK.·~t ?r':':',e:1t l\' ~_~~ply;t:"i : ... Jr ~)r· .... hlU(lnlr:.! thlS ,,:ompl~x .::..)mpon~nt ";r:."t'!ns -;J·jn~l. 'l~nlii;:..lnt adciti0nal \tIor";.c. 1.";; '~·r..j.·,1 ~_' ")nSl"1.t .. !nt 1'1 !tle~t jl~l£'nsional requlr~l11enr:; Ind :J d"':~ll,..l'\I~ ';3S tl~ht. stnJC- INJECTION MOllDED : Jrl.l·,; .;. 'una :~)lnts ~et..,t.:"~n _ YDPOnents .. ....... ,rk lS i}rOci!'~din~ )n schedule. \'~ : 'Oil ;,\5 I F:;;:il ~ACKPLATE .\SSE~BLY :-hl S :-!'1~ ~3';;lfi~r ~ac~plat~ :p;,:;,-·mblv. ,ho\Jn in ~·~~Ilr .. : '. : "\m!)rt'~" ]i1 ~'1nt»r .,a~,,!)latp lnd an 'J~"'r "\.j:,(p~,1.t··, ...,)t~ lr·· '!""l·l·l,,: .... d ..,.: ~3(\ If :l:"ltt"f""'...! .llpna ';'1.i.l .... ':\ _.i:-~l>:. ·l~ ~:i.n··r ~ac~plate is fabrl~at~d tr~m .s~pressed and "re~n-lDa.:hi.ned billets. Th~ "'Jter ~ac;'plate .5 injecti.)n-molded. This is the largest in- J",ction-molded .:ompollent (at a · .. ei~ht of 1.8 ISOPRESSED AND GREEN MACHINED , TE82-5911A Figure 10. Gasifier hackplates. Ii)] Ib) in the ACT 100 ~ngine. The vane po<:ket holes in t~ outer b.ckplate ~re ultrason1ca1- 1,. _chined after sineering. ... CT 100 5£.o\L PI.ATFOIl.'f/EXllAUST :>UCT fhe seal platfona/exhaust duct "hO\m 1n Figure 11 is fabricated by Corning Glass O/orks from 1ithiwn aluminum silicate (LAS _ode ~~)8). At ~ weight of 17.6 1b, this duct, produc~d ~ slip casting, is the largest single ceramic component in the ACT 100 engine. After SllP ~.1Sting and ,.intering, only the bore and :la~e thickness require final machining :0 """et jit3ensional requirements. Sondestruct 1 V"" lnspect ions of these components >,;enera11v re- veai no =tedal discrepancies in high stress ",,;<:,on5. Evaluat10ns of similar LAS q~)8 ~aterial lndicate an avera>,;e room temperature fracture str"'ngth of 12."~ <.si with.) '''eibull .,.odulus C)f 12.2. fhe primary strength-controlling de- fec ts "bserved in these test bars were .uriace ?ores. Preliminary ei_vated temperature tests 1ndicate that this strength level is ma1ntained to a temperature of 2192'F, although some plas- tic deformation was observed at ~his tempera- ture. Further investigations to characterize this phenoillenon and to determine the te"'pera- ture level at which deformation occurs are currently underway. TE82-6117 Figure ll. Slip cast Corning LAS "eal p lat fora/ ... "haust due t. 188 !h~: and engine experience with :nese ~ooa ?Onents has !>een extremely successful =0 date. All throee parts subjected =0 a -.ecnar.1cal pressur-e test desl~ned to simulate pressure differential loads at engine :aximua paver op- eratio~1 have paS !H!d , and the !.AS seal plat f01"lll1 exhaust duct installed in the first ACT 100 engine bu\ld encountered no difficultieJ. ACT iDO INSUI.ATlMC 511 L't L>EVELO~llT TIM! use of st%'uctural ~erallllC components 1n the hot flow-path sectlon of the .'CT 100 engine. while allowlng higher turbine tempivision 0: General 'totors. The ~aterial is an isopresseJ and ~reen-roachined fine-grain partiall~ sta- bilized zirconia (?Sl) consisting of hoth CUb1C ar.d monocli'lic phases. It is a derivative of the :naterial used for the production oxygen sensor on all recent Qf aut~biles. rhe ave rag ... room temperature fracture strength measured .In longlt'.ldinallv ,;round :,ars is :'9.80 <.si. The strength ior the .)s- fired ,;urfaee condition is :'5.69 ksi. Frac- tures primaril~ originate from small pores for both surface conditions. Preliminary elevated temperature tests in- dicate that this strength level is essentiallv maintained to a temperature of 183:·F. The thermal expansion and heat conducling capacitv, of parI: icul,~r interest in thermal barrier lIa- terials, measured 3.9 in.lin./'F and 0.088 cal/g/oF, respec t ift ly, at a temperat ure "f 1472·F .. Th4!se insulating shims are heing installed in AGT 100 engine huild No.3. T£82-011S Figure 12. AC Spark Plug PSZ insuldting shims. Advanced Gas Turbine Ceramic Component Development -\E\S TR -\,: T The \.~.lr .. ~!t Ford \ ..... ~ T! 'J1 r~ .. "'lt;r..l·'1 '.,a~ Jro- gressed I')r-:>ugn :r)It;"i;e,:~n. :a'>ncatI0n. -.ind :If,1 general Ion aerodvClarnlc ,:-:>rnponenl te,ts. -.inC '"Uf- rentl" :s focused ,>n engine tesl jed ::levelop'ne'lt -.ind cerarnlc ':l)mpOl1enl develoor'."t. 'eslg'l -\ ("ef ,l'ni(' components -:Jf t'xce-Ilent VIS,H' '~ualitv ..,ave 'Wf'n receivpc :r.)''l !',t' \iRest'ar-' ::a5tl'-'" ,-"''loan,. C..lr:'0r·l~~u·!") ",)"~~~an\". 1..-: .. 'r'1.:)~. r. v1 _inC ~Cl(. These ','YI1DOnents' are .. 'mg quallf led f-:>r ('n>;ine testin~ through seql.ence;)f evaluations that include "ulk 1'~nsitv. 'JOE. jl'nenslon~1 :n5pection. visual examination 'If> to ~'Ix ·nagndic.lt:on. selected "TIechanlc~1 .:mcl :~ef'nal screenmg tests. ,1nd >tatK structure- [q~ te'>!s. Individual static str'.lCIUfe .:er.l'nIC components have "een :juallf:ed up w ~ I')')°F ,., :'wf'nal >cr('enm~ tests. The :o'nplete coer ..l~)IC sr..lliC structure. conSisting -:Ji :.q ,-o'nponent" "'as successfully '>een tested under -"eIK condlt:ons .CI t"'e sIalic structure test rIg toJ [he \100 I jC'si~n ,:ond.tloJns oJ{ I {'OI)"F. " ~'la;1"l~ [oJt,>f. fabrlc~ted COODerat:veh' j" -\d<'esearC'1 '~,lsttng (:,)mpanv .:md Ford \I0t0f , .. ::,Yl"lpdiV. "las :)een -;Dln ~t.""stE"'d at !"OOfn te'npe-r 3!Ure : ... 1 : 'J2. -.:r/j r::»'11~ r"lt" \'-~-:-:~: e"'1g:.ne :t..~st ~ed {F~~'jrt" :' '''.:is spt.:...c!- fiC'l11\' :Je51!~ne<1 ..1round lise of Cer3l1l1C components :r. the hot flow ?ath section. Except for the regen- erator flow separator h0Using, all ceramiC compo- n~nts are 5y·nmetrical; this provides a more unifocm stress distribution and eases manufacturing. AGrIOI development. depicte0 in I'"igure 2. begins with a 1600"F turbine inlet temperature version. Testing of the 1600'F engine test bed is weU unde·r- way using metallic structures. Initially. qualifie-,ot sectloo hadware that wll! !>e qualified in separate test rl~s. -\ metallic, dual-allo. turbine rotor will tJ.e used in this version. Finally, ~ engIne :s upgr.,d·,-d ~() !'Ie ~ St)0"F verSlOO. This is acco"TIplished bv introducmg the ceramic radial turbine, thus per'nittin$!; a turbine inl .. t tempei"ature of 2500"F. Substantial progress in ceramic technology has b«>n ac<.'Omplished on the Garrett/Ford -\G T1 () I pro- gram durini: this past three years 1-(1.. Progress!>y ceramic '11anufa.cturers :"as ~ key to the suc- cessful demons.trations made to date 5- 7. Figure 1 shows a composite of the cer;lmic structural parts and tur\)iM: rottN' St.ICCes,')fully fabdcated to the required engine dimensional envelope and delivered to Garrett for evaluation. All components are ~val uatt.>d using bulk density measurements. 'IIDE. 40x • ST E IISIIlE - FIRST BUILD 16f~n TIT ?IOO ~ TIT AST ENGIME - fINAL BUILD Z500' f TIT Figure 2. "'Grt')! Engme E.olutJUn. J , / ,----...... visual examination. and dimensIOnal lnSpectlon. Selected components are 'nechanicallv and/Of" thermally screened ?rioc to static structures ng testing. This paper reviews the status of 'nechanical and thermal screening tests. static structures r;g testing, rotor spin testing, and additional work 'con- ducted under the .\GTl')l ceramic component devel- opment tasks. 190 r0f clac~v. :'"," rotor jeveloprne r : :asks will '>e- 5ep.il.fated from :h .. 5\ lctures devel )p'r."". '~d .. \{-:I '>e dlSe.lS~ :i~st. TCRBl~E ROTOR DE .. !..OP\IE7'lT - \IECH.-\7'I- IC.-\l. SCREE"Il"4G - C0ld spin testing of non-bladed and ~laded rotors (Figure 4) 'las been utilized as a neti'>od of gauging developmental progress a.nC iden- 8tAKlED R01(!R SIMULA TEO IItlTOR Fi~ure~. \G T' ':: :- Jr:,me Rowr \pDroac~. tlfvtn~ qren-sth-::'n:::"" :l.}" .. s :,) ,uppon Jrocesstn~ lter..itlons. I:1Jt;,-1~l ..... 'l,)n-")l.lded : ~)t,1r ,\01:1 ~~st5 ',,-"'ere used :lS .l doe\·eloP··lent.}: 'te,)pln~ ,tvn(' :vr the cer '}'T11C ·na.nu!3cturers Ie) " ,)nr("ntr ate eo !for t' ,)n ach lev mg t"'e ,)L'c('ssan .. ,.} te': .1; 'tren" t" .lnd If"- for"nlt\ !:'l ~ . ,e ",1t, .. )," 'uJ. f'l("lo..:lr< "Itrt~SSe50 .lI.ere ;)~~ dieted t·) ~,.,. :'3 "s: .• 1 this ':>ndn,vn. T>fvugtl iter.lt;ve develop'nent. "X'th F,)r~ \\ot0r : ~J"lD:,:1\ .",d -\Il~e<;e:lrch Castll1g Ce)'TJP:l.I1\' i \,-:,:1 .IC~ ,e\,.,.d t~1(' deSign .werspeed ~oaj _,i : I 5. ')')') • ;J'n I:: ~-:>ern:··1t deSign). .\ Ford >.Cltert'd re.}e'tlon :landed ,11I,'vn r1: tnci(" ·lon-~)i.lded "' )tor .... J,5 '"<)n !e"t~ : ,'"I '1~. ';')') r?'l1 i;:>e3.1"\ ..;!."eS5 "3 .... "'1;', .Io.lt\.h)ut :J..~'1~(>,. l"h~ .1~' :\CC sHltered ~:i.C\·H ·1~ ~r~de rlon-Dl.3.Jed "'L1t Jr .... .)<; spin tested to ;: ",'jlj') cD'n Without !.ldure. Ya"I'lg successfullv p'n :,Iaded rotvr ~evelo;)'n<"n!. Early blarled rotors Wlt~l visible :,Iade :le!ects · ... ·ere "pin tested to eV3.luate • ]tor 'lub integritv. \1:'10Ugh portions ,of bl.ldes !ractured from these :":nown defects at speeds as 10· .. · 3.5 79,000 rpm. ~'otor hub survival to 115.0')0 and <)').')00 rpm "'as respectlvelv achievt"d f0f F,ord .}nd \CC rotors. The -\CC r,)t0r 'na, 'nve .}tt,'lIned h.gher sneed except for 3. cr."k. ti1at In! tuted m the ,)13de, and propagated :nto the hub. T')ese early ,..,in test results demonstrated that the i1ig'l ':ub strength aCClieved in non-bladed rotors :lIs\) IS ~eing cIChie\ed ,n jladed r,)tors. Rotors recently received from Ford and -\CC S:10W a 'narked improve"nent 111 blade quality and .~'.Jrrentlv 3.re being prepared for spin te5' evaluation. \ "",'f !.lbricated c=peral;vt'!v j" F:xd .lna \CC "k15 :oeerl successLlI\v spm tested to 30.')01) rpm and thus. IS qualifieC to(" initial ':ot tu'bll1~ rig testing .. \ sirT1llar rotor (~igure)l '.'·3S spi" tested to bilure at 1')2.')00 rp.n ex<..--eeding th'" 'naximu'11 design speed ;,f the ACT! ')1. TURBI~lE ROTOR OEVELOP\lE:-.lT - THER \\.-\L SCREE:-.lING TESTS - Following successful cold spin testing, the turbine roto( \l(ill be thermally screen tested to eva.luate blade integrity. -\ simple. hot turbine test rig (Figure 6) has been fabricated for this evaluation. The rig utilizes common -\GTlQI- metallic hoit flowpath hardware and will ~ operated 191 F,~ure ~ .. -\CC Ceramic Turbine Rotor. F:l':ure {.. \GT'~I Hot Tlrbme Test Rig. :,) ,,':1·J!a.te .l ,!'hJtd0Wf1 tr:msient (the w0r,t stress '.}se for "llaCI'1g). Preparations are underw.lv to ,)Itlatt' t"$tm~: when .;uccessful ;n thermal screenmg tests • ..I cot,x :'1en w:I1 be qualified to be~in en~ine te$tln~. "T -\ TIC 'STRUCn':RES \\ECH"'~\C-\L "CREE'l\'lG TESTS· Selected static components are ")("c'Hni(,ll\v t<:'ste'd .n ,lp;Jroxi.n.ltelv ! 20 percent overstress ,-e>ndltions using either pneumatic or h,'dr ,luli(' ?l'eS5UreS. The flow separator housing, re~en<::r:Hor shield, turbine backshroud and turbine align·nent ':>olt system all have been successfully tested. Re:ilJlts of these tests arc encouraging and indicate that the qualitv of hardware received to ciate is Vt':fV good: over 90 percent of those tested, have passed. 'ST.-\ TIC STRUCTUR~S - THER \tAL SCREE:-.l- I'IG TESTS - r\naIytically, the predicted stress distri- '>uticn fOl1' most itatic components is largely thermal and peak'S during an engine start transient. In an effort to screen inadequate parts and later thermally map satisfactory hardware for analytical validation, several thermal screening rigs have been designed and fabricated. These t«!st rigs were deSigned to expose ceramic components to thermal transients up to 2100'F under normal engine start transients. Hot flow path geometry is simulated and an AGT diffusion flame combustor supplies heated air to the rig. Engine mass flow and temperature ramp cycles are simulat'ed during a start transient. Real time tem- peratur,e, mass flow and acoustic emissions are moni- tored throughout testing. Tc) correlate a fracture event to a particular start transient condi~ion (temperature versus time), a real-time fracture sensing mechanism is required. ,\n acoustic emission system has been adapted, con- sisting of a high frequency response acoustic trans- ducer mounted on a metallic waveguide. The wave- guide is inserted through the rig sidewall and is in close contact with the component. During a frac- ture, a high level of energy is di< _:pated due to the breaking of material bonds as the crack propagates through the ceramic. This is detected by the transducer as a higher decibel output, than typical background flow noise, plus a large number of acoustic events. Testing to date indicates that acoustic emiSSion can be used to determine ceramic fractures during test, and further, can aid in deter- mining if rig/engine disassembly is warranted follow- ing a test sequence. Figure 7 illustrates some comparative characteristics observed during test. 104 103 102 OUTPtlT TYmAl OF U~ml\fllAGED CUIA~1t HlIflIrIVIIH£ BACKGFlOUIlO ! nOISE -----1 / FILTER ~ . .' i ; I flOW flOlSE I I OUTPUT TYPICAL OF Cllf,C!((D CERAMIC H,~RDWARE , --~ 101 ~--~----~--~I..-~--- ro 40 6!l 80 100 120 OWGtlS Figure 7. :\coustic Emission ()ut;>ut :\5 Recorded by a Distribution :\nalyzer. Thermal :;creening tests ~ave t>een conducted 00 the transition duct/combustor baffle, and turbine shroud/turbine stator/turbine backshroud. .-\n initial test of the turbine shroud alone is conducted prior to assembling the stator and backshroud in this rig. resting has been accomplished in two stages. First, ;1 set of components was screened to 1 600°F fOf' initial structures rig testing. Sucsequentty, a second set of components was screened to 2100"F. ,\ minimum of five lightoff cycles ~o temperature, hold fell" 3 minutes, and shutdowns were accomplished. Figure.5 8 and 9 show components qualified for ZIOO"F structures rig testing. Figure 8. Ceramic Thermal Screening Test (Transition Duct/Baffle, 2000"F Cycles). , l l .I \! , , I I / \ , I'!gure 9. Ceramic Thermal Screening Test (Turbine Shroud, Turbine Backshroud, and Turbine Stators; ? I aO°F, 'j Cvcles). ST.-\ TIC STRUCTURES RIG TESTING -\l1:hough a set of components 'TIdy pass a 'Tlechanical and/or a the~mal :;creening :e5t, a 'T1ore lcnportant quahficati0i1 r-:-mains - r.ow does the ,lssembly Interact"") The ,-\GTlOI ceramIc ~trlJctures rig was :1e~iigned to subject a 'ua compliment ()f static struc- :Jffal components to simu_Iated engine thermal and --rte-c!lanical loads, transients, .ind to allOW j!nportant di.a.gr'OOStic work to be accomplished prior to engine t~Li."'g. The rig, shown in FiguTe II), is essentially an "'GTtOt engine without a rotating group. The regen- eriltoc has been retained such that simulation of the asymmetrical mechanical and thermal loads imposed ::m the flow separator housing could be evaluated. The high pressure (HP) and low proessure (LP') regen- ef'ator flows ve independently control1ed, an,ousing, turbine shroud, and ceramic bolt assembl)·. The concentricity and nor- i' .... ~_ .;1" 193 Figure 13. me s tart, indicatin~ :.~le ?otential of ceramic comoonent fracture. Disas- seC1blv of t~ test rig re-)'ealed a fractured outer j;f!user hous~n~ as shown .:1 Fi~ure 20. Analys,s. ;; .. ~u .-~ 2,). -\l~ T;: l ~'="~ ..!~-:'2 ,~.J:er Diffuser '-1011sil>g !Or ac: _-,_~ Ift.Jring Rig T,.stin~. md~ :>\e :ra":5H~nt ,'vell' ?<",:!"for-ned, showed a ;>ea, '~rl"s. (above :f. ~;stl in the -egion 0f the fracture-. '-eYf'!' al:orre--::;'e .)Otlons .. ere explored. '-;imlJ3.' ·'1<.>t:ll Darts : x :~,<.> -\G T I 'J I 600"F engine had ':>e-e-'1 r ;;dl.llly slotte·: to ?revent a ')oop stress ::,uilduo and ,;lj::,sequent wa!:>inp,. L'sing t~ cS concept, the par't .. ':H rt·.lrulvze<;>ped to 3 ksi. In arl -! ff or! ~., conL'lue test ing. ~ second part 'N as recor'}- figured as stated above. The fact that this "fix" is not permanent and that other solutions do elcist (i.e. alternate materials or turbine exhaust diffuser redesign) is recognized. The rig was rebuilt and testing continued. As shown in Figure 21, a temperature cycle (compressor discharge at ic\le) to 1600"F (simulated ~ 1200 ..... ~ 800 u..II a... :E 400 u.t 1-' __ iD ... _L.;;;.E ---f,1 ~.,eRUISE 4 , It. __ -'. __ ..... ___ ~_-'---'-_ 8 12 16 20 24 28 32 TIME. MINUTES Fi~ure 21. (~erd'T1IC "truc~iJres r<1~ Test Cvcle. Tin Wd~ -lc'1,ev{'d ,wN -l : -:cj-s('cond time span. \\"'55 flow \'idS ':1dinuined .it ! J lbi-nln (idle .:-onditionl. T~ls ,~(v1d:t~~)n ·~\ ... l<; ~1('lrl f)r ! ') 'nlnute~: ~t'len '.vas .n(,"'~~.lY"'<,~ ~." ~.1 ".~: i ' .. :."t:"l ,,,'1.1e i,)idl~lg !f,'J'J°F TIT t)r . ~ n;"lqt~"': ~'"'\e .;,,\-,!f"''';i ~~len .... .)0;; ";'~ll1tduwn. POle .... 'l \~t"r ...i""U: (: .. )I'llOl.)!'1ent<; .vere jdbJ~cted to fiftet"fl !~1('r'n~il -\,~:t."''l .1') ,~~"(~rl~{"d ... loove '.vithout inCIdent, TIle 'In.! ',\'as """","'e'J fro'n he test cell ,\11':.1 1 :-;,--l~"'e' ·l~lprl. ·\ll 't,."r J.·n tC '-\Ynp~)nents .were ',J:')(l.rJ"',-1~""1 -1!1d '1!kl~lflt,""d !,.x .n!:~~i f"n.gtne ~est ~lnd ·:vdLld!:~"'I~ ~\t :t)jG"F. Pi!'): .... :~f" ..... t'\ .":!tldi .::.tep !n .-t"'r ..l.·~1:(~ ''\·:''\·J,.)nt.''a'l~ .~e\ ("i")D';1e!1t J.nJ ~e~lns !v :ip'nl"'n"-lt:"~\:·:' · .. ~1.");~I~\' ,)~ :"it:" -\\..~rt,): ~ • .?''i:~'1. !'T~~;~F \~-'~ r~'Tl'\..~ - !7) ',)fl'unctl0n ",r!t~1 :t:"~~l·Y~.~: . '\·")~h,'nt'''·lr :.~,,\~';;',. jn .nt-:"r!..lce :~0 n[)dtl~tljt\' ..... t:..:lh .~"·.""1:>, ..:, ;~"':''''c? -,'\rh.~~'{-·~e1. \ll ::He-rf..lcf'" :~)nC.::,"""" :Y" .. ,~ ... \'-~ r~:' .~~).\!' .. ")t~~q ~~'1!dle'd, ,is ..,:h.)\1,,··1 ,"'\ ':.!..I ..... • '\,~. \:\)fH~ ,I" ~~~l .. • .. ':Jt.. ... C~:\f .. ..,~:-~ss ,\n(1 Figure 22. (nterf.lCe CO'np,lt!:Jlhtv Tt"stlng. te-nperature environments for the three engine oper- ating conditions 0600, 2100 and 2500"F TIT). To date, the study has partially evaluated interface conditions I, It, and III for all combinations of mate- rial choices. Test bars of as-machined or as- processed material were stacked with a 0.25 '( 0.25- inch contact area for conditions 1 and II, and a 0.01 )( 0.25-inch contact area for condition Ill. The specimens were heated to the appropriate temper- ature while dead weight loaded at a minimum simu- lated engine asse:nbly load. Once at te'nperature, additional dead ",eight loads were applied, as required, to simulate engine aerodynamic or mechan- ical loads and field for 20 hours. Unloading and cool down followed. The specimens then were inspected for sticking phenomena. Three classifications were ~ssigned: no stick, no reaction ('.ISR); light sticking (L 5) upon cool down. i.~., came apart during hand\:,~; :lnd hard sticking (1-15). not separable by hanJ. Concern is raised for L 5 and 1-15 conditions due to the following: o LS - longer exposure "nay result in hard stkki:lg o HS - could result in com;>onent fracture if the part~ thermallv ·~'(pand or cool down at differ- Ir.g rates T_\':>I.~ I ~ummM::~es the testin~ for interface condi- ~ion~ I. 11. and Ill. Te~ting ,It conliitio'l 1lI. deoicted in r:-:~'Jre 21. '.\'3~ ".mdlJc:t€'d under d ('"onstant «, ,-Les, !,)ad (€'n~ine .lssc"nf)l" ;>rek)arl) ani results showed '10 "tlcklO~ or reactinn, LOAD • [" __ , __ I J =oJ a·SiC ~.---'------~ C·~~l ___ ... RBSN ---- "] _=r~ ~8sN1 195 F ,.:ure -: 1. '~,).npdtl')t!ltv f€'st ,~,'nd'th)n "\I 'nne,. III - Interfdee \\aterlal ~-:o...,blndtl<)ns. \5 noted in T .lble I. ,ever ... 1 'naterial ':o'no,na- ~lonS result in stldon~ 'nder ,:on(!Itions ( .tnd 11. \dd!t,,'>I'lal :"'itln~ \Va', .:,)nc\ueted !x t'lese ~Ynb!Cla .. ~I()nsjstng :Ia,ne-s;xaved ntlllite ,:.:)dtHl~ ,:)0 .)"le Interface surface. P"ellminarv results mdicate t"'at no stICking ;)( reaction occurred With !lame-sllrav~d ,,)ullite-coaterl surfaces. \lthough additional t".!'sttng is :llolnn~. lnd 'V.'ir- fa,nted. these preliminary results mdicate that the \GTI'l1 cera'Tlic d~·v€.·lopment ':3n C>f'oceed under t'1e following guidelil1es: ' .) \ttention 'nust '>e ~ivefl to -nateri;).l co'o- '>i"'ltion selection ;) Coated til-SiC 0/' RBS;\I can X- used !Of' ,ele-:ted Interf.lCe cO"flbll'\pear to help in alleviating sticking phenomena TURBINE ROTOR SHAFT A TT ACH\tE'\jT - The ceramic turbine/coupling attachment study also has shown very encouraging results. '\ concept using a double-walled cylindrical coupling, shrunk fit on the ceramic turbine rotor sha.ft, has been evaluated under cyclic thermal testing. Results of these tests indi- .::ate that the racheting l>henomena can be predicted and controlled. IN907 material was selected for the coupling due to low ther'llal expansion characteristics and strength properties at higher temperature. A 0.u045 to O.OO5-inch di.lmetraI intederance fit is used to <:.ffix the coupling to the ceramic turbine shaft. 0\ series of tests 'lave been conducted on speci- mens in a furnace. The specimens kera'11ic stub shaft/coupling) were subjected to thermal cycles from below 300 to over 1000"F. ....fter 200 cvcles. total movement was I).'J006-inch aft (toward the tur- bine). An additional I ')(1 cycles currently are t)eing conducted to verify initi.Jl test results. Following the second test series, the coupling will be assembled on the turbine rotor for hot turbine rig testing. These test results then will be assessed an::t used to qualify a cera-nic roter for engine evaluation. SU\\\\ ..... RY - .... GTI'JI ceramiC component devel- opmt..>fIt has progressed from the :lesign and process fabrication phase to screening evaluation and initial feasibility rig testing. ~igntt.cant dcco~n!llish'l1ents achieved durlng the last "ear Include: o Ceramic ~Iaded turbine rotors have ~een 'pm tested to greater than l11),')1)1) rpm. exceeding the maximum speed requlre"nent fur engine operation o Individual ceramic components 'lave t>een quali- fied for 210O"F In the thermal screenmg test rig o "' complete >et .)f c'era'nlC static structures con Slstll'& of ;'0 .::wnponenh 'las !:>een success- fully te;ted LlndN ,7vclic conditions :n the structure, test rIg to !(,(jO"F-this '>et now :s readv for engme te';tl!l~. -\chievement .)! these J.ccJ.nplish'"T)j~nts ':01\- tinue;; to demonstrate the feasi'1I1it\" .)f the Garrett! Ford smgle-sha!t. slIlgle-stage engme. frorn !'le 1>tandpolnt !:>otn .)t joe-sq,n and 'naterlals. 191 ~CKNOWLEOGE~ENTS The authors would like to thank DOE and 'IASA for support of this ~/ork under contract DEN 3-167. TIley would also like to thank the individuals at AiResearch Casting Company, Carborundum Company, Corning, Ford \totor Company, '\jGK, and Pure Carbon for thdr efforts which have yielded substantial ceramic component fabrication progress. REFERENCES I. "Advanced Gas Turbine (AGT) Power train System !)evelor-ment for Automotive Appli- cations", Progrl~ss Report '\jo. I, October 1979- June 1981), DOE/NASA/0167-80/I, '\jASA CR-165175. November 1980. 2. "Advanced Gas Turbine (AGTl Powertrain System Development for Automotive o\ppli- cations", Progress Report '10. 1, July 1980- December 1980, f)()E/NASA/OI67-8112. 'IO\SA CR-165329, July 1981. 1. "~dvanced Gas Turbine (AGT) Powertrain System Development for lI.utomotive Appli- cations", Progress Report "10. 1, January 1981- .1une 1981, DOE/NASA/0167-'II"l. 'IASA C R - 16790 I, l)ecember 1981. 4. ".o\dvanced Gas Turbine (AGT) Powertrain System f)evelopment fO( .... uto!Tlotive .\ppli- ('"at ions". Progress Report "10.4, luly 1981- ne-cernber 1981. DOE/'HS .... /OI67-82/4, :-l-\S ..... CR-167983, July 1992. 5. Storm, R.S., ""let Shape Fabrication of .-\lpha SiC Turbine Components", presented at the -\utomotive Technology l)evelopment Contrac- tors Coordination \'eeting. Dearborn, \tichigan, 0ctober 26- 29, 1981. (,. \tangels, J. " .. , "Sintered Reaction-Bonded Si)"I4 for the -\GT IOl Turbine Rotor --\n t Ipdate". presented at the '\utol1'lolive Tech- 'lology !)evelotlment Contractors Coordination "eeting, [)earborn. \iichigan. 0ctober 2&-29, 1981. Styhr, K.. "Fabrication of Silicon "Iitride Turbine Engine Components", !}resented at the .... utomotive Technology Oevelopm"-'nt Con- tractors C()(){'"dination '.iee-ting, Dearborn, \tic~i~an, October 2&-29, 198 I. ~. Kreiner. r>. \to and r>. \V. Richerson. .. '\dval\ced Gas Turbine Ceramic Component r>evelop- 'TIent", present~~d at the .... utornotive Technology T)eve!opment Contractors Coordination \k>eting. T)earl)orn. \1ichigan. October 26-2<). 1981. '-_ ... Ceramic Technology Progress Report DOEI AMMRC Ceramic Materials Program ABSTRACT During the past seven years, AMMRC has been actively engagE,d with the Department of Energy and its prede,cessor organizations, in building a ceramic materials technology base aimed at the vehicular gas turbine. The focus of this work has been the various DOE, Advanced Gas Tur~nE! (AGT) efforts. Figure 1 lists several of t ,significant achievements attained both in-holl at AMMRC and on contract, under DOE/AMMRC IntE~ra ency Agreement IAG DE- AE-101-77-CS5l0l7. Many pf these achievements are currently contrtbuting'to the AGT programs. However, as tIll! AGT prog~s near demon- strat ion, the windo" for support~g materials research and development to impact· these pro- gra.ms is closing. Accordingly, Al'IM~ and the DOE, Office of Vehicle and Engine R&D'il.ave dec.ided that it is appropriate to redire'et the A"R-IRC efforts to contribute to a more generic ceramic materials technology base aimed at both the gilS turbine and diesel, for both light and heavy duty applicat ion. o ~'ITI"L TtC~OG'f ASst'Sy,I!(,-t ()iI\ t£RA.Mlt 'M!1I1:IAI.S A\.tl :('II\!9QI'I{1\T'S ~ YMl • .l AtJ't()MOTtVf GAS "'"JOI:'I'\{$ • :If:rs • 'I·'AI.. :l'l."Cf\r.S~1U.11Cf\ :;t: '7 ,: .. (R ~lSS"a~ Sl'~"'" :;I S l'4 . y., .::hhO;VoO'l'tT "" ~.v\:) .. IGI'I-:tf.l..l .... llI~'f ~o~-tc'il' 'nl' ~iJ)",Q£S .~ \1'i.AS;.sA( H ){Pl~Oi'-<[ QI: CAI\l)IOA"t EV;ttrt,£ C1UVlt5 . ~,n R. Nathan Katz.oo Edward M. Lanoe Army Materials and Mec:h .. ics Research Center Thi$ present~tion will outline ou~ future plans. under the c&ntinuatfpn of rAG DE-AE 101-77 CSSlOl7, which addres~-the above goals. FY83 PROGRAM DIRECTIONS During the coming year, AMMRC, in close. coordination with the Oak Ridge ~ational Laboratory, the NASA-Lewis Research Center, and DOE's contractQrs, will carrv out R&D which exploits the technology base previously developed, is consistent with the available resources, and addresses pacing ~eramic materials technology issues for adv~nced engines. As outlined in Figure 2, the OOE/MtMRC Ceraroic !iaterials Technology PrQgram for FY83 .lill encompass 5 tasks. The life prediction, sintered Si3N4, and time-temperature dependence of advanced ceramics tasks will c.ontribute to both future gas turbine and diesel progr~~. The toughene.d ceramics task will be dedtcated to diesel (.'Ugine materials. Support to the lEA implementing agreement will continue to fa(;;11i- tate data exchange and technical communicatton on ceramic gas turbine programs between the e,s. and the Federal Republic of Germanv. We hope that during FY83, that this agreement will be expanded to include other lEA mem.ber nations . Duriftg.-the past year, ,",ork was initiated or continued ()ln~ tasks. A large por- tion of the past year's 'p~-1)ft -tch~ sin- tered Si3N4 task. is b£lng presented by Pasco .~ltlO~'T (\' ""1tiO-\'tlP S'''fiill A.-.J;l YOOt.IlA~ J9'i:S~fIt ~""')!.iSS ""p rtC~IQvt . :_ of,'lilST ~'SIU. Sl'itl'SS ...... F'l> .. A.( :I&.fA. PA51 tOR 1:1.:1 ... )( .... $1"",, S'l't "-\0 s< . t"11 1'0 1"0 .Aa ... ...c£tl P'Q~:E!ruRlS ~) S1A,nSllC,..'-1. :::4T' hAl.;Ail"" .... \..4) ~If:i Iffl[!uc:rt()\· !.191'Q ~ _________ a __ • ____________ ~ . , ,,~nd en,~iGI~,J.A-t.heil:,-1IXesentat ion. There--"-l J. r::.~ . ..P.u:s,c>xIUH __ ·~ha~;h:e plans ' !i: : and preliminary progress on tasks relanng to life prediction, time-temperature dependence of advanced ceramics, and toughened cera~ics.t·~ Flgure 1 l:I,A.r:.I. _,.J 199 -l~ \IIfIhQ~ - -- . - ~"'t ~ ...... \l.4ft" .. , 1M; ~"~('f'~ :,)P'>'hfluf : ..... ~"'I )I ').-... r II'rC ""I)foo.«! it."..£o ... t, ".'\1 _ .. - ~.~n' .. I' 1f(J>~ - ~ .. ~" .. , ~ .:,....:10" ..... '\ .~"'~ .... fIC! ~ft.r"-('· ..... !._ ·t.'"\)'tf"~rlt ~~("""", A~ ... <'" ."J"'(1 - ,,,,t, ... Of.~~~ ~ "''10' <.ryCJ :f0:7...v:-,.",,,,. .. t\ ~f""'" ...... ,,'-'. ;1 .... Jf'fI! -·--~..,.t'''''''{\ .:)1'1'0/'1'11 ~ "l1 h '-1'f""'-.;, '~"''''''''''''!'''''';~''""''"4"''l ,4'"o1t'f."lO .... .- • ,:..-~ ',(0' ."PJl''>~ ... . ......... ., .. V_t·, .. \_" ~,..., . At-; YPf.r\ '>-o:'f".T<::'" '''''''''-' I":~.~ "-':tlJ"'of"J'(" TASK I - LIFE PREDICTION ~HODOI.OGIES In order tCo address the goals for life prediction shown in Figure 2, "~'INRC's F'\'82-83 emphasis is on the areas of statistical data evaluat ion ;>rocedures and the detenninat ion of failure :nodes and life prediction para'neters of selected matj!rials. STATISTICAL DATA EVALUATION PROCEDURES - Over the past f,~w years, ...... '11'lRC has expended considerable effort to further extend its computer code for statistical data evaluation procedures for six statistical functions; normal, hlgllorm.al, Weibu11 ::!, 3, I. 4 parameter, and radical, as well as, incoporating non- parametric techniques. For these functions, the code now includes the capabilities listed in Fl~ure 3. fi®R( :0-'~~~i.-Z06isr'\T ISrIcAl:)AJ;~l-~;i~'~~ ~t~~~~i ~~~~i'~~;mmrff'$.~&~1Q1jjj~~mr~~ .~b! ;1 9 ;~ ;:,q(1)~Sllln 'l"iSIT" ;!;~T1iY4S ~l' ;_,\(TI0'i4.l ~tpQiS.E."l~TI()'I.-:' During FY82. t~2 ~C in-house code vas extended to in~~lude Robustness and multi- modality procedures. The Robustness procedures are based on Huber's H-estimate method and: obtain outliers in a forasl manner; have single and multi-variable capability; do not require the assumption of normality; improve the func- tional represemtation of data; and provide improved inferential statistics. Th~~, the AMMRC code is now able to syste- matically determine outliers, indicate ~hether or not. multi-modality exists (i.e., mixed mode failure), provide formal determination of best probabflity distribution fits, and provide confidence lilll.its. In the case of small data sets. nUlllericBll simulation procedures are pro- vided to enhance reliability computation. DETr:RMINATION OF LIfE PREDICTION PARAMETERS FOR 5lNTERED SiC - The static fatigue resistance of 1980 vintage. sintered alpha silicon carbide has been assessed at 1200 and 1300'C by stress rupture experiments. Figure 4 shows the reqults obtained by Dr. C.ovila at Ford (under Al'lMRC Contract DAAG-46-77-C0028). To the best of our knowledge. this is the first tensile stress r"pture data on sintered alpha siHcon carbide. At 1200'C, the loss of strength with time can be modelled on a log stress log time plot by a line with a slope of 1/27. This result is remarkably close to the value of 1/25 obtained by Quinn at AM!'lRC who utilized fout: point flexural stress rupture testing. Fr~ctographic examination of samples from both studies revealed that slow crack growth 'Jas ~ the mechanism oi failure, hO\rever. and the n values derived from the slopes shou~d not be interpreted as slow crack growth (SeC) exponents. Sevcrtheless, Iiie prediction estl. ... ates may be made using .hese slopes as "effective" SCC exponents. That the strength degradation slopes obtained in separate studies of the ,;alae material in :5eparate labora- tories, using c iff erent eXl'er iD'ental techniques coupled >lith the fact that botil studies included te",ts in exces~ of 1000 hours Juration, should ~ive a hi~h degree of confidence to desi~ners. r .... SK II .. -=r:STERED 5ItlCOS SITRIDE Fi~ure 5 lists several of the major hi- li~hts attained in t'1e ::>OE/,\.'e-mc "lnteno-d ':i~~;4 task. The work under cont ract at ,;E has 'produc;:'l a sintered silicon nitride with unexcelled hith temperature propert ies (1). Wor'k on this con- tract to be performed in FY81 uill concentrate ou reducing the percentage of the beryllIum containing a,ddltive (Si5eN.,) ulli Ie maintaining the materials ~ique high temperature behavior. 1~r-______ , ________________ • ____ ~.=.~=.=.~~~~::~ ___________________ · ____ ,'4S _.,.d AIIIIIa IICce_ ,_I ". !'l .. (..!L) .... Va '. 11.0 11.' H.O iii " 43.S I ".0 21.75 .~~______ __ -L ___________ ~ ___________ ~~ ___________ L-, 14S 10.000 0 .• 0 1.0 .00 '000 Figure 4 - Tensile Stress Rupture Behavior of Sintered l-SiC, with Inferred SCG Exponent. :-I (R. Govila, Ford ~otor Co .• ) - Contract DAAG46- 77-C0028 Work recently completed under contract at the University of Washington (2) has provided valuable infortllation on the wetting behavior of liquids in the Y20rAl20rSi02 system on Si3N4. \"203 + AlZ03 used as a sintering aid reacts with native S10Z on the Si3N4 powder to form the liquid glass which enables the a-Si)N4 solution ·-Si)N4 repreclpitation reaction required to "roduce high strength material. thus, under- standing the wetting behavior of YZ03-Al203-SiOZ melts on Si)N4. can aid in obtaining mo~e homo- geneous microstructures. It was observed that only liquids in a limited compositional range between 4Z YZ03-38 Al203-20 SiOZ and 67 Y203- 13 Alzo)-ZO Si02 produced wetting. The best ""en ing was obtained with a 60 Y20J-ZO Al20J- ~O ~i02 composition. ~ CO/IIIRACl 'OMG4lt-81-C~)' c>"'z GPS Of s,~ WITH !;(I'>l~}'XIOE 4DOITIV~ ",8.*,>' .,MQR !SShll.U~ 'lA! ~! .• 1iXI'C "JI;!.~tHUD \TlllSS RUPTUII! h'iD cRH~ 8lHAVI0Il .. itO1'\: OXIOAIICf, ~'l ORD[~S Of »..>.GNIT\JI}[ lQWER T~" HPS1'j c.A,R£SlARCW(;{ OU-IQ Of I"'J,CTlOfl M'lI.OASIl1TY AM) SllillRABllIrY '!:.~~~.~»INGT()/II. ';(},HRACT '0AAG4lt-N-C~: .. OHlI;!.O RIGI"'! \\~tR£ Vf>r-'!zOl-S'Cl-z L1QUIOS IIU S'}'14 ~~. '''-HOoSE o1 201 The AMMRC in-house program in FY83 will focus on the use of nitrogen pressures (up to 100 Al~OS) on the sintering and resultant pro- perths of the Si3N4-Y20]-Al203-Si02 systems. Silica c~ntent is adjusted by controlled oxida- tion of the Si)N4 starting powers. Figure 6 i.llustrates the different oxygen content obtained from four different starting powders as a func- tion of oxidation time. Thus, it can be seen that each different st&rting material will re- quire a different pro-cess to yield an optimal end product. Work performed in FY82 demonstrated that it 'ros not possible to fully densify compo- sitions in the Si3N!.··Y203 + Si02 system at pressures up to 20 AIMOS of NZ (at 1800 to l8S0·C). In FY83 a 100 ATMOS capacity furnace will be available at 1~f.MRC. and it is believed that this pressure of N2 will be sufficient to obta1n full density. Work will also continue on sintering time-tell!perature-pressure cycles to ortitnize ?roperties of materials in t.he Si3N4-Y20rAl20rSi02; system. Olld"'lOn Te",p .. loo:PC lAin IJ L----L--------1~L______LJ ~ ~ ~ l~ l~ O.1t}dhon TIMe tmiOl Figure 6 TASK III _. TOliGHENED CERAMICS Because of their unusual com'>ination of properties (E steel, K 1/5 to 1/50 that of Si3N4 or SiC, an a steel, MOR 100 KSI, and a high KIC 10), transformation toughened zirconia (TTZ) are leading candidates for cylinder liners, piston caps, head plates, valve seats, etc., for the Adiabatic Diesel engine. Thesl! materials are age-hardened ceramic alloy system, .. <; an,} as stich they a~t! likely to be Husceptible co overaging and loss of strength at long times at high temperatures (Le., close to the age hardening temperatures). nle possibility of overaging with its likely negative impact on materials performance was identified as a critical area of ignorance in the prelimina'ry technical assessment on cera- mics for dies,el engines presented by A.'1MRC at last year's ceM meeting (3). Accordingly, a task was initiated to: (a) define the extent and magnitude of the overaging (if any), and (b) develop t.()ughened ceratnic alloy systems which would n·ot be susceptible tQ overagipg at temperatur·es likely to be encountered in advanced diesles (llOQ-l200°C). The first subtask is being carried out in-house at AMMRC, while the sec·oud subtask will initiate this month, at the University of Michigan. Figure 7 gives an overview of the objective and apprQach of these two subtasks. --- ------- ~T"Sl I ~I~ .~~~_~ Pt. )CH'OUR "'~t: OIAcn .. t :>lfl~ l)tUM Of. AGI~ ~'tON-l~. " .. "..,. "'''PItOACH ~Sl. I . l)[PO~ CO\J~~ ~OR 'tAIUO\J\ •. , ... ~ ~VAL"'''''( (.,..'\G.t~ I~ ~~ C~'f X,,>,fy ,,'I(AOS7a'JC'uAf (Ie :)LWttSIOftS ! ~,.\t II . f.AlUAll '-'C" "'to O.\ll,,'tf '!(Nt AnEA! ! tPf)~.~Rf Sutu,\« II . ~E~p &"A il~~~~':~~~~ ;a I ~~ IfE" ""1,lll')I'''' 01 \l1(""GA"t ,j6.lf:C!llft ::.t:vtlOP O't{IlACI-..G Il1SIST ..... ' AUOY ').')':1t.'1., !,,~ .') :1"11-'( AP~()o\CH' ,)(AH' "'~('?'>l 'rtrt~ AlLv'" )f')~tU') SCP.U\; \'\U\Un LrO?~ "l~O~ S1'J,TIV\ f,A~JAt[ I~ r\\O ~~s A'l ,\ ':IuS'A')_ I ______________________________ -d F 1 ~urt· PRELIMINARY RESULTS OF TTZ AGING STUDIES - Five commercial zirconias, of which four are TTZ, are currently undergoing aging studies at AMMRC. As seen in Figure 8. some of these materials show no apparent change in microstructure after 50 bours aging in air at 1300°C while others showed considerable microstructural change (grain coarsening and pore agglomer;ltion). Preliminary results sho\led that materials doped with ;'2°) and produced by sintering in the two phase region are more stable at high tentperatures than those doped with MgO and produced by sintering in the cubic region followed by annealinlt in the tetragonal r.egion. Material N of Fieure 8 is an example of the first type of material, while material F :[s an example of the second. The situation with regard tv the other experimental parameters is less clear. While evidence for phase and thus density changes exists, it is not presently clear what portion of this may be attributable to phase transfor- mations occuring during specimen polishing. t'uture testing on unpolished samples to be sub~ected to ~OR tests should help to resolve this ambijZuity. What can be stated with :ertaintv, however, is that all· TTZ's studied thus far. e~hibit some degreE! of phase transfonn:>tion and microstruc- t.ural or dimensional change with even brief (SO hour) exposure with no load at 1300o C. PREl..IlHNARY RESULTS OF STSR TESTS ON TTZ - Since a w\jor port ion of the Task on Toughened Ceramics will entail stepped-temperature stress- rupture (STSR) testing (4), it was decided to obtain early eA~erience in this area by conducting such tests on a proprietary ~ stabilized TTZ. This lIWterial is currently unde,- evaluat ion at Al1HRC for a, IIlilitary application. The results of this study, shovn in Figure 9, clearly indi- cate a significant reduction in t.he load carrying '. '61. 0 ." • .. . ~ ~' ... ." Iae> .. ,.,,1 . e - 0 •• • iI 0 •• • 411 • 1>,. .. • 0' • '" .. ' . . .• 'tal e-f ,a' ~'" f . • oo~ ,. A" 1"JOfi>C 5Oh, ~~oo~ • eo ... " • .. • 0 .,.. ~.<8 'httli'l"4l' r; £ llpoM'd " ..\ • l.)(I;()"C ~ ... , ti9' ~ ~~ Fig'jre 3 - !'licrostru<:tural Appearan:e of 1\."O Co1!llltercial Zirconias Sefor4~ and After AgltLg capacity of this _terial with time at teu.pera- tures as low as 800·C (in air). Several con- ventional stress rupture tests have also been perforraed. 'l'\io 5-R testa at llOO·C and 150 HPa load resulted in fillilure at 205 and 188 hours. Both samples had hlrge permanent deforaations and failed in the creep rupturE mode (i.e •• many cracks on the tensile surface). One sample has continued to surface sa testing in excess of 2300 hours at 900°<: and 200 HPa load. While our preli1l1nary results confirm the validity of our COflverns about the aging behavior of TTZ, it is important to maintain a balanced perspective. By defining the U .. itations of these materials, the .anufacturers will undoub- tedly be able to address and alleviate many of the problems. It llhould be kept in mind that even at the present state of development there are many applications in Adiabatic Diesel tech- nology for a tough, low thermal conductivity ceramic which has II tensile stress rupture life at 900"C in air am. 200 MFa (29 KSI) of over 2300 hours • 10 ...... . _L-__ .. ~. -- _ .. ,' - ...... _ ... 1_. ___ _ .. ... tUlI, . .:-' .. TASK IV - Em-TD{PERATCRE nEPENDENC£ 0F ADVA.l"CW CERA."!ICS Durln~ the past vea.r • .i task to "valuate the tilllc··temperature dependence of the strength of !leY candidate heat engine ceranics was re- initiated at AMMRC. The effect of pre-oxidation on the stress rupture of full,· dense silicon nitride was evaluated in a Joint study with the Ford Sc tent if ic Rel~earch lAboratory (')}. It was sho\ol\'l that pre"oxldatioll at < 12~O·C can lead to reduced stress !Cupture life times if the oxide scale is left intact. Stress rupture tests of GE-sillter~ silicon nitride (SiBeN2 denslfication aid) vere also conducted. Based 011 a 12oo·C stress rupture tellt of t.his _terial in air at 275 MFa (40 ItS!) vhich u been running for over 5')00 haun, this _terial shovs the potential for high temperaturEI stress rupture life far beyond conventional hot pressed mate- rials (Figure 10). Ouring t.he cOI!!Ilng year, in addition to S-R evaluations of various TTZ's, new versions of both GE and GarborundUlll sintered SiC, and GTE sintered Si)tl4 will be carried out. Where feasible, it is planned to coordinate materials and testing "ith the Air Force/ITTRI test program to 3Hsure .aximUlll cODl!!lonality of data bases. '000 '0000 'oooco .. ....,.·O'.', ... ·f ... 0....\ - The FY83 DOE/ A'I.'IRC Ceramic :-Iaterials Program is tarf,eted af. significantl" advancing [he sta~e-of-the-art in critical areas of: e Ceramic Lif e Pr€'d ict ion 'lethodolo~', and :Jara .. ~ew eel'amie 'tateri<~ls Development e Process Development e Se,,' and Ir.lproved '!aterials Screening :' or advancE,d gas turbine and d iese 1 eng In(> .ll'plicatlon. We look f0t"1olard to reporting si~\nificant results in each of these areas at the next Contractor's Coordination ~?eting. R£FERENCES 1. Pasco, W. O. and Greskovlch. C. 0 .• "Silltered Silt.:, for High Perf o TlIIIance Thel'1lllO',Mecilanical Applicat lons". ~c T~ 82-99%) Si N4 containing 0,7% BeSiN and ~3.5 wlo oxygen as srntering aids was scaled-Up~O develop a property data base for '!1,e in thermomechonical applications at high (~1300 C) temperatures. The fracture strength in 3-pt bend for test bars ~0.6 x 0.6 x 4.5 cm was "-440 MPa (63,700 psi) for a span length of 3.8 ern. There was little drop « 15%) in high temperature strength 'ilt 14000 C in air. The creep resistance was outstanding at 1300'i. tOI 14000 C, as evidenced by creep rates of 'v4 ~ lO--h- for a st,re~ of 207 ,'.IPa (30,000 psi) at 1400 C and ~2 x 1O-"h- ior a stress of 3115 MPci (50,000 psi) at 13000 C, and a total creep strain of 0.11'l6 for a Si3N4 bar exposed for 650 h under an applied stress of 345 MPa at 13000 C in air. The olcidaygn rates in ox',(~n )'vers v:p low and were 7.4 ~: 10- and 2.1 x 10-"1 -Kgim- 5 at 1300 and 14050 C, respectively. __ -...J I. INTRODUCTION GE~f_RAL ELECTRIC CORPORATE Research and Development, under contract with AMMRC IDAAG46-81-C-0029), is developing sintered Si1N4 for high performance tlhermomechanical applicati6ns. In a previous contract (OAAG46-78-C-0058) a 2-step gas pressure sintering (GPS) process was developed to Yield sintered 5i N 11l1th a densIty 01 >99% of tne<.)fetical. Typi!~ a'pplication 01 the 2-step GPS process consists of first sintering the sample to closed porosity at '-2100oC undt.'r 2 "'Pa N for "JO minutes followed by 3. second step at 19~2100 C under 6.9 "'Pa N2 for '·30 minutes. Those sequences )ldd S'3.N4 with iii. density >9':)% and ..... eight loss of . 2%. The purpose of this current contract was to scale-up the process to prodoce test ban ("'0.6 x 0.6 " 4.7 cm) tCI geflef'atc a data base for this material. The composnion which ,vas studied contamed Si]N, • 7% BeS1N 2 • 3.5% oXYllen. Another objective 01 this Wayne D. Puco and Charles D. GmJuwich General Electric Co. Corporate Research 8lId Devalopme!\t ScMnectady. NY contract was to - xe fully understand the GPS process which is be'Coli.ing more widely used by other institutions. II. PROPERTIES OF GPS Si3N4 Table I presents a comparison of properties achieved for small (0.2 x 0.2 x 1.9 em) and large (0.6 x 0.6 x 3.8 crn) test specimens of GPS Si3N4 • Small specimens were fired in a small high pressure sinter- ing furnace with a 2.5 em diameter x '4 cm long hot zone. Large specimens were fired in a large, high pressure sintering f.urnace with a 9 cm diameter x 10 crn long hot zone. T.I,N.E I Sm.ulto..l: .. O.h.l.9(m) ~O."Iii).".}.kmJ "'od\tJ\A 01 R~h"'. n"'c 'fll\thtrn~a.)' ",0 M.Pa'nhl.A) 11OO"c U) "P;a(md2.'i '<1, :-oo"c "A <'0 I XIOoC 'A , ... -..rffp :lOO03C •. ~1l1Q· 7~·lu,·t \U'I«J h)'J· ...... 11~)W.Pa.l !400"c t....'h:Hf'· i U,' \th' "&112',\-1(2'01 \lP.,l ... 'ou<3olt.on .yXl" ,a,,' .2 . 0.«.:."', .... ·. ·.*,cl,,·I\,2,.,., .• ~.1 .-.x~C " 1.1&10+ 11'12"".,,,.1 .'\00'\:. .. "sO' ,l'Cl ",.-*'," ... '1l :.~""!'I' \,.2 'fH'I~!ut4) ''''~"'\"' , The room temperature modulus of rupture for the small specimens wa." 597 "'Pa with a \1Ielbull modulus (m) of &.3 as compared to 440 \lPa With an m:7.! for the la.rge specimens. The decrease III strength with increasing sl~e IS consistent and In good agreement with stressed volume scaling theory. SE'" examination ot fracture origins revealed that porous regiOns < 100 ;.;m or inclusions ill the bulk are respon- sible for failure. Improved processing will be requir- ed to eHminate these flaws. "'pproxlmately 90% of the room tempera,ture strength IS rnalOtalne 2.1, an enthalpy of activation of '·(,00 KJ/moie. Microstructural obser- vations showed the formation of isolated ca.vities in the glassy phase pockets at 3-grain intersections i., the tensile rel~on of creep SpeCirT '1S. Figure 2 shows that interconne~tion of these cavities occurs along grain faces as the total creep strain increases. TEMPERATURE (·C) 1500 1400 1300 Ii!OO ,o-3F STRESS • 69 Mia lilt I "- : "-I "NC-132 BY 6£ ~ Uo,oOapli) -;- -4~.E. HPSII ,,6H - 54HJ I MOLE &:. 10 I '11TH 7'U.Si1l2 "" l .... ! MI-n';U/IilOLE '" ",,' 0 / -.-SiAIOM:III, ~ ~\ NC-132 BY SELTZERi a: \ (COMPRESSION) !: 10-5 6H-628kJ I ' 10-6~. lo-lL 5.5 AIlNEALED GPS Si]184 ----. GP5 513114 WITH 7'1. 8.Si"2 MI'600kJ/Ii!OLE ) I 5.7 5.9 6.1 6.3 liT (OK X 104) i I I I I I -1 I I I I I 6.5 6.7 Flpe I St~..ady state cr-.ptAt2 rt. liT ler CPS ~~, and tor tlOt pees.ted NC.1)2 5~lN, U:S..l.r03tlvo .lIt99% density. .\:though the effect of pressure on the densification kinetics during the second step of the GPS ;:>rocess ;,ad been investigated, the effect of temperature had ··,:·t been fully explored. To better understar.d the second step of the GPS process, a series oi -·Ig cylindrical specimens (0.9 cm dia.· x 1.0 cm high) were fired. The conditions of temperature, pressure and time for the first stepwerp kept constant .it 21450 C in 2.2 MPa of N2 for 30 rr:inutes and yielded a final density of 92.3% and a weight loss of 0.44%. Specimens were fired individually with the para- meters of the first step held constant and the para- meters of the second step varied, but only with respect to temperature. The pressure was maintain- ed at 2.2 ,\\Pa rather than increased and the iso- thermal soak time was 30 minutes. The soak temper- ature of the second step, final density and weight loss are summarized in Table II. T".SlE. n ~1~ i.~~~:! 'I'" : ",'IW 0'" :-.. .... Y..ll-~}-12 So \eCC'oI'Ki stl:'O ~2.} J.4f\ s..',,,')2·'n-!l ;;:;~~: i:; ~~: ~ :II~ ~}.6 1.8) s.. .... ~2-'.,..1. H,9 ').91 ').'X!2-9)-1} t9i)oc. 1.2 \1P.a. JO min ~8.7 1.':3 SJ'\I}o2-'J~lb 19)}oC. 2..2 ~Pa1 )CJ rrun ~.9 1.7'7 :'-'OO2~9~17 19Q}oC. 2.2 twtPa... )() run ~).! 2.18 :he first step of. the process yielded a density of 92.3% at which point dosed porosity was obtained. By increasing the 1lo1d time from 30 to 60 minutes und"~r the defined conditions of the first step, the den,ity only increased to 93.696 and the weight loss dOUbled. By maintaining pressure constant and de-- creasing the tempera.tureb the densit)' reached a maximum of 99.9% at 1955 C. The density decreas- ed as temperature was decreased to 19050 C. The point to be emphasized is the unusual result of increasing density allld weight loss with decreasing temp'!fature. The first step of the sintering process requires heating the specimen containing'" 7 wt96 207 BeSiN2 and "'3.5 wt% oxygen to 214;oC, in 2.2 MPa of N2 for 30 minu~~. This ~reatrr.ent prevents the therr."ial de~omp051t!0~ of ~13N cue to high N pressure while permlttmg a hquig phase of unknow~ composition to form. The liquid is believed to be a beryllium-silicon-oxynitride initially, which prurr:otes liquid phase sintering. As the SL~N4 dissolves, trans- ports through the liquid and precipitates out, the compact densifies and decreases its specific surface area. It is believed that the precipitated t3 -Si N is In fact a B-Si1N4 solid solution containing signtlic~nt amounts of B~ and 0 as confirmed by x-ray analysis. It has been observed that the densification proceeds to a "limiting" density of 0,93.6% after 60 minutes at 21450 C. Further increases in temperature may pro- vide additional liquid pha5e to permit further densifi- cation, but probably at the expense of the mechanical properties due to increased grain size. The sintered specimE"'1s shown in T able II were polished, chemically etched and examined with SEM. Figure 3 shows the microstructure of sample SN502- 95-12 which ~ad beer. fired. at 21450 C, ::.2 MPa, 30 mmutes. This contrasts With Fig:;re 4 which shows the microstructure of SN 502-Q 5-13 wh;ch had been fired at 21450 C, 2.2 MPa, 6:> minutes. The most prominent observation is the large increase in grain size caused by a 60 minute soak over the 30 minute soak. It is believed that the ~rain growth and concomitant pore coalescence are the cause of the observed "limiting" density h93.6%) which occurs when the 214-50 C isothermal hold is extended to longer times. The increase in grain size indicates that the time and temperature parameters ot ttl. first step of the GPS process are important in con- trolling the final grain size. Figure 5 shows the microstructure of SN502-95-14 which wa" fired at 20450 C, 2.2 MPa, 30 minutes in the second stp') and achieved a density 97.9%. The grain size is sr.,aller than that shown in Figure 4 indicating that decreas- 109 the soak temperature in the second step not only increases the fired density but serves to maintain a smaller final grain size. Smaller grain size was observed for sample SN 502-95-15 (Figure 6) which was fired at 19950 C in the second step to a density of 98.7%. and for samgle SN502-95-16 (Figure 7) which was fired at 191~5 C to a density of 99.9%. By d~creasl8g the soak temperature in the second s~~p to 1905 C, the density dropped to 93.8% and no funher gains were available at lower temPeratures. The reason for the increase in fired density with decreasing soak temperature at consta,1t pres- sure during the second step of the GPS process is stil! not .tully understood. However, one possibility for the Increased densJ.fication is the increased solubility of the N2 trapped in the closed pores with decreaSing temperafure. If the N2 solubility in the liquid phase increases with decreasmg temperature, then the gas pressure in the pores will oecrease and th~ remove the ba .. rier to pore dosure and densificati'on will proceed. The equilibrium composition of the liquid phase as a function of temperature is not known and therefore cnly speculation as to composition dlanges is possible at this time. · - - ~i&ure 3 - 5[\\ photomicrograph of sample 5"502"·95- 12 ",hlCh was fired at 21450 C under 2.2 \\Pa of "2 lor 30 minutes. Figure ~ - 5E\t phol!OmlCr0?Saph of $3'llple 5-":502-9>- 13 which was fired at 2145 C undei' 2.2 \\Pa 00 \j~ fQr 60 ,nlriutes. ~ , , t F'gure 5 - ';[\\ photOl",(fograph of >ample "'~~2-'I>- 14 ",hlCh "'a~ f,red _,I 2!4~oC under 2.2 \\Pa "I " Lx }(j m,nute, In the 1st ste-p and Zr,450C • ..nde'r 2J \,Pa "n 'i 2 fur 39 'o,outes "' the- 2no 'Iep. , , , F 'gpe r:. • '>E\\ photOlll'C1"0f-tdph 01 sample :>;0,; )1)2-9>- i ~ ",mch was hred .it 214) C undeT Z.~ \\Pa .:>t ,~ !-x }(j .nli'ute'i ,n the ht step and 1995 c: lEiCer zJ \lPa to!· 30 'OI''lUtes 10 :he 2nd step. OF ... , \ F Ik~ur\..· - ..... L \t ptH.H<..'"Ii,\ r\.l~f.j,ptl 0t ... ...l'·lplt." ..... , V;:_,)')... ,f-- .\ 1,\ ~I .... ..1') !.r."Q..11 2t4.,0~ llndt."f'" ?2 \\P..l tJr ,S I!;\.!~"~ ,"' "1(" l'lt -.tC'p ,J,n(] ;'i~"".\.~ unct"'f 2.2 \".P..1 ,)t '\, _ :dr 1, ..... ;( :r~'lte') ,:'; ~·1t." ~'h! ':l",). C. EFFECTS 0F SOAK TE\IPER:\ TCE ON DE:-.l- ")ITY I:-.l THE FIRST STEP I:-.l TH~ 2-S TEP CPS PROCESS - ~intering eX~~rlments were conducted on Batch SN 502-100 to det'ermine how low the soak temperature in the first step of the GPS process could be and still obtain closed porosity. It IS the slIltering time and temperature in the first step wh.ich predominantly controls the final grain size of the slOtered specimen. From the standpomt of achIeving Si 3,'J 4 ceramics with high modulus of rup-ture, it IS essential to minimize the final grain sIZe. It was anticipated that if dosed porosity could be achieved 111 the first step then the application 01 high "2 pressure in the second step would result 111 pore closure and a high density specimen. Closed porosity occurs at '. 92% density and the results of the slI1ter· II1g expenments are presented in Table \II. T~P' P-r~u~e- '~Tl~ Rt":l.. Oc-n. • ~l,:-t l~" ~et~ -l!!-. ~ -:..!~ ~ ,'/" \) --.- "K~-.))-;: :'Jlj} .~ '< H.l :.'W. ,,''0':.,)(r l .i:50 ." ., "".: :.~1 ,'y).!·lO'.}..') .... ·l 112 .., .! ... 1 ",-,'10:1':.,'),')." !~'O .,,, >0 " ;."" -" stote-ring temperilh.lf'e of at least 19800 C 111 the first step was required to obtain close<1 p<.Xosi~. A spedmen (SN 502-1 OO-~I) was then fired at 2000 C for 30 minutes under 315 psi of N, m the first step and 19450 C foc 30 minutes undef 1000 psi -)1 :'\l . Although the fired spedmen had achieved closltl p()('osity In the first step, It did not go to full density upon applicauon 01 high pressure. It was again obsened that the weight loss increased \IIi th decreas-- mg temperature in the second step. :\ !;eries of experiments was coru:luct~~ whei'ein the soak tempef- ature in the first step was increased and the condi- tions j. the second step were kept constant at 19~oC for 30 minutes under 1000 psi N. The results are presented in Table IV which ~tl\at by increasing the sinterin« temperature in the first step to 20950 C it is possible to attain a final density of > 99%. rAM-EN """'fie l!!J_t.!2 _Step =-I~ ~..!!!o~ SN)()2-' 2IlOO"c. 10 ...... )10,,,, I,.)"c. lO ...... 1000 psi .l.Q I,'l ~)().2-IO 2tll'oC. 10 '*A, )20 ,1Itol I~"'''c. lO ""n. 1000 .... ~l '-'" \N)()2-11 2Of,O°C. 10 rnan. no Sill ~:~: :::: :::: ".1 1.91 \N)Ol-l) :<1O,"c. lO""",))() I"' "'.1 2..'" It was ob5erved that the soak temperature in the first step must be 0, IOOoe above the temperature at which closed porosity occurs if > 99% density is to be realized in the sea:md step. The reason for this is not totally clear but it is believed to be associated with the amount and/or composition of the liquid phase developing at these high temperatures where no phase diagrams are available. IV. SU~MARY Sintering of Si3N4 with 7 wt% BeSiN, and '- 3.5 wt% oxygen additionS has been demonstrated to yield densities '>99% of theoretical using a 2-step GPS process. The process has been scaled up succ~ssfully WI th no degradatIOn lO (1) the modulus vf rupture at room temperature or elevated temperature, (2) creep resistance, or (3) o)udation resistance. Sintering studies have revealed that the chemistry of the system is complex and no phase equilibria data is yet available at the temperatures of interest. V. FCTURE 9iORK Future work Will continue to address new addi- tives which will enable reductlon vr elimmation of BeSiN from the system. The key issue will be to flOd 3h additive whICh will densliy S1 1!'l4 and still mdlntalO the excellent ;>ropef'tles which have been demonstrated "11th the BeSiN~ additive. Other ave- nues of \I1vestlgatlon Will be Improvt"d processtng techmques and a reduction 10 final grain size in order to Increase the abs:>lute strength of these Sl r'J 4 ceramiCS • \CKNO\\iLEDGMENTS ThiS work .... as sporlSIXed b> the :\rmy ~\atenaJs dOd \\echarllcs ReseMch Center unae:- AMMRCJDOE lnterageocy~greement EC-76-A-IOI7-002 as part of the DOE. DIVision of Transporfati->l\ Energy Conser- vation, Highway Vehicle Systems Heat Engine Pro- gr am and carTled out in the PhYSical ChemIstry LabOl"atory of the General Ek-ctnc Cor!lOl'ate Re- sea.rch and Development Center, Schene<:tady~ :'\lew York, under Cootract DAAG-46-SI-0029. Mr. George Gazza was the Program .\~omtor. " / . The authors would like to acknowledge Dr. R. J. Charles for his overall guidance of the program, D. G. Poiensky for considerable help with ceramic pro- cessing and hea\t treatments, C. O'Clair for ceramic processing skills, and the ,\taterials Reactions and Characterization Laboratory for x-ray and micro- scopy work. 210 ---------------------------------------------------------------------------- Highlights in the Development of the KTT Automotive Gas Turbine ~~r To provide some background and orientation. the main features of the KTT (Kronogard Turbine Transmi ssioo) System are reviewed and illustrated. Then a few CO!llilents are included about component and s;ubsystems develo~mlent before the Mark I en9ine and vehicle testing are sUlTlllarized. The outlook for the Mark II engi ne is assessed. i _-----1 FEATURES OF THE KTT SYSTEM The KTT System is a very compact three-shaft regenerati ve gas turbi fie engi fie closely integrated wHh a very simple transmi ssi on. Fi g. l! is a photograph of the complete engine and transmission - the !CTT Mark I engi ne. A cross section of the engine-transmission system is shown schematically in Fig. 2. The arrangement is somewhat simil ar to a free power turbine with the veD' important exception that a third. auxiliary turbine is added afte.· the pO\e.· of gears. Hi gher than 2:1 torque multiplication is achieved. hence, higller acceleration rates are achieved; accelerration lag is reduced. It leads to a ~al1er di~ter turbine with reduced stresses in an three wheels particularly the high t~perature first stage ..meel. This allows for early application of cleramic materials in the ~i gh teQperature turbi ne wheel. The tlho 1 e arrangement leads to reduced size and 211 Sven-Olof Kronoprd United Turn"' .. ~mo.S""-n weight of the whole engine package. It moves the torque converter function out of the tranSMission and into the gas path a 11~ ng the recovery of some 80 to 90'/, of the torque converter losses which are usually dissipated in the transmission oil cooler. Thus, energy losses fr~n the power turbine are recovered both in th' auxiliary turbine and in tne regenerator (see schematic diagram in Fig_ 3). It permits more flexibility in the aerodynamic design of the turbines. This, plus use of variable geometry, gives higher efficiency particularly at part load. Further comparison of the KTT three-shaft syster.1 with conventional single and two-shaft systems is given in the schematic sketches in Fig. 4. As indicated by the Roman numerals, there ah,s led to a simpler, smaller. or more cor.lpact engine-transmission pack"ge. Further evidence of this is shown in Fig. 5 where all of the parts of the KTl Marl: r eng'ne are compared with all of the parts of a cO!ll p3lrable production V-6 pi stan engi ne and trdnSlllission (taken out of the Volvo). A sil hOitette cOlilpari son of the two engl nes is shown in Fig. 5. The fully equipped KTT Mark I engine installed in a standard Volvo 264 automobile is shown in Fig. 7. The size of the engine COOpart£1eflt could be red\ICed considerably. particularly since no radiator is required. C0MPOM[NT TEST AND DEVELOPMENT A pflotograph of the cOilipressor and di ffuser is 9i ven i FI Fi g. 8 showi ng the backswept ----.,------------------,--------------._ .... --------.... ---------------------------------------------------- Fi g. 1 - KTT l>tark I Eng1 ne 212 \:T TPT T AT - torque from compressor turbin" - tt)rque from ~ower turbine - tl)rqu~ from aux!liarv turbine TX+y - t0rque transf~rr~d from auxili3r~ turbin" to compressor turbine - torque transferred from auxiliary turbine to p('1wer turbine Fig. 2 - Basic KIT System ConfigllY'ation 213 ;---- Fig. 3 - SChematic of KTT Dual Enel"9Y Recovery r I 1l~.-'-~;"~- .J '·1,' - .J l' l' Fi g. 4 - Oi fferent AutOlllOti ve Gas Turni ne Dri ve Trains 214 Fig- 5 - Parts of KTT System and of Production 6-Cylinder Piston Engine and Transmission 215 Fig. 6 - Profile Comparison of KTT ~rk Eng; ne and V -6 Pi stan Eng; ne 211 Fig. 7 - The KTT Mark I Engine Installed in a Volvo 264 Automobile Fi g. IJ - CO .. lpressor and D1 ffuser on Test St~nd 217 igpeller blades and straight diffuser vanes. Current peak efficiencies are typically in the 80S range (sor.tetilJles a few points IIIOre; sometillles a few points less) with a wide operating ral~e. Continuous test and development eire in progress to further broaden the range and illlprove part load efficiency. ~ch ti~~ and effort lJave been devoted to i nstruoentat~ on lind lI1eaStori ng equi pment to detenni ne th~~ detai 15 of flow ~ft.1 mechani ca 1 beh~vior in these tinY, very high speed components. Very small probes powered ;,y serVO-tlotors are r:JOved in and out and rotated very precise~y to accurately probe the flow in nozzles, ducts, and critical flow passages. Oi rect hi gh ~)peed torque measureclent equi pment lind techniques were also developed with an English Campill\)'. Also .>pecial test rigs were developed wW~rein subsystems such as the power turbine and 'the lIux'iliary turbine can be run and loaded i~dependently dnd together, so that complete perfonnance maps can be generated for each component and 50 that component interactions can be studied. Another test stand called the hot secti on test ri g is set up wi til d r.lOtor dnd a burner so the speed and temperature I)f the first stage nozzle and wheel can be varied independently. Two turbine test wheels are shown in Fig. 9 - one 15 a forged powder ~Ietal Pratt & ~hi tney Gatorized wheel; the other is a cast wheel. It should be noted that r.letal cQf:,ponent developr.lents are not standi ng sti 11; there are many interesting improver.lents emerging. Ultilalltely, however. 't is believed that ceramic materials will be necessary at least in stationary hot section parts. Ceramic material in the rotor is 0115-0 very desirable. But. even though we have run a ceramic wheel in a turbine pOl>!€red car, ceralJlcs still have a long w~ to go. Ceramics are expected to be used in several area~ including: heat exchanger cores, i nsu' ation systems (such as that of FOS£CO) for housi n9s, ducting, shrouds (for clearance control I • nozzles, and burner liners. Fig_ 10 shows a KTT rotor system wi th a cerami c coopressor turbine wheel (hot pressed silicon nitride, developed in cooperation with AS£A), a ceramic burner liner (REFEL 5i C, developed with BNfLI, if silicon carbide (developed in cooperlltion with Carborundura) nozzle ring, and an injection molded 5i 1 icon rli tride tyrbi ne wheel (also with ASEA). Fig. 11 shows two injection molded cerilJllic wheels, one in the green fom (before processill9); the other is if hot pressed s11 icon ni tri de "mee 1- While mali)' of these components are now runoi ng or scheduled for test, our efforts h need for special control elefll€nts for the auxiliary turbine and special balancing and vibration control for the three-shaft system. As Ire slIs;pectt!d, no spedal or added control elements are needed. The same control as that used for a conventional two-shaft, free power turbine satisfies the requirements. Also no Sl)ecial problems with rotor balancing or vi brc'!ti OViS have been encountere(i. Development has been free of bearing and gear failures. Operation is SlllOoth and autOlllatic. lne KTT Mark II engine represents the next generatiClll of the KIT system arId it is expected to De a pre-producti on prototype. The Mark I I contains all of the k~ features. of the KIT system, however, it has many changes <'limed at reduced (:ost, smaller size (down-rated) for a compact vehicle, and higher' fllel econ~. The closely integrated tranSllllssionis aimed pri.rill' for front -meel drive. It includes a differential, but it also provides four-wheel or rear-~lheel drive options. It hu only one regenerato,' core. Fig. 14 shows both the Nark 1 ("ight) and Hark II engines along \:lith the basic rotor system and a regenerator core. Figs. 15 and 16 show outline and cross-sectional sketches of the KIT Mark II engine. A IIOCk-up of the l4art II is shown in a Fig. 9 - Two Turbine Wheels; Left is a Forged. Pot'J'del' Metal (Ga tori zed) Wheel; Ri ght is <1! Conventional Cast Wheel (INCO 7131C) aUD Fig- 10 - KTT Rotor' System - First Stage Turbine Wheel is Hot Pressed Silicon Nitride; Nozzle Ring is Silicon Carbide; B~rner REF£L Silicon carbide Fig. 11 - Two Turbine Ceramic Wheels; Silicon Nitride in Green Fonn (Left); and Hot Pressed Silicon Nitride (Right) Fig. 12 - Volvo 264 Automobile with KTT AutOlllOtiY.e Turbine Installed. This WlOlS tile first car in the world to operate on the road with a ceramic turbine wheel in the engine. 221 • ...................................................... 1 - ....................... . ......,, r------------------------- 501 n ~ l~ ___ -------------------- THREE SWen llledsured. Detailed Jlleasurements have b4!en postponed for future parts of the development program. Regarding future fuel, based on component tests and studies, initial fuel eco~ will be cOlllpetitive with conventional piston engine powered cars. In the long run, conSidering emissions, particulates, etc., ~ expect to equa~ and surpass diesel powered cars. The gas tUrbine should be a winner in ma~ areas of application. - -,-, --.. ----~----..:..-.-..----...:.... HEJ\VY DUTY TRANSPORT TECHNOI~OGY SESSION ....... , ..................................................................................... --........ ----- DOE/NASA Hleavy-Duty Transport Technology Program AtlSTRACT ~iS new program is int"need to provide a technology base for industrv to use in develop- ing heavy-dutv transport engines. 1he pr~ram focuses on advanced l'iesel engine technology. waste heat utilization. ~aterials. and tribolngy. Appli~ati0ns noti2~s were s~nt to indllstrv to encourage their ,deas ,md partl2ipation .. "n excellent respllllsC' was received as lndicati'd. ~~. the receipt of over 80 proposals addressi~ var- ious research activities applicable to heavv-s to b~ approximately ~O ?~rcent hi~her t~lan in th~ ~ear 1980. 8~a\lse of :his trend there is a neent ~ff0rt ~ ~1re d1.re-c ted towara methl."lds ,'! ln2reasin~ ~~~t:' : ..... 1..:-ti0n ,-,i lls~tul work pt!r .;~: ,': ::··~:c:"l I:"!l~~r-=!" .:: ... 'nsuffit--.d4 .\ ?ott"nt1.all,! attra.::t,v" ~pp,-c)a.:n ~o achlevlng this objective 15 ~I..') ~xtract .ldditional use-illI work from thi!' exhaust :>'1 ·.lsing a turboexpander or other bottom- ing 2vcle. Furth." .. ~ains in useful work .:an be achie~ed 'v insulating :he engine, where major heat losse·s "";: u.,-. t twrebv ,,[ iminat ing t he water = 001 iog ,;vstcm, rl.J. s i 'Ig til<' e"haust temperature, "r.d i""reasing th" ?otential to extract more work from the ""haust. This is the concept of --~kper70ro><'d for V.S. Department of Energy under Inter>Lgencv Agreement EC-77-A-31- 1011. Harry W. Davison National Aeronautics and Space Administration lewis Research Center Cleveland, OH the aJiabetic engine. Additional gains can be achieved by minimizing triction losses in mechanical components. This approach to improved diesel engine efficiency is being investigated by American and foreign engine manufa.:turers. cummins Engine Company under contract with the Armv Tank Automotive Command (TACOM) has achieved 5 ign i fi2 ,lnt redue t ions in spec if i.: f ue 1 r onsump- [ion ~v ~liminating water cooling in a turbo- .=harged and turbocompounded engine. They projec t up to 40 percent fuel savings by redue ing heat loss and friction loss. The Japanese Kyoto Cerami= Company in cooperation with lsuzu Motor C,)mpan:_ has successfullv operated an uncooled ;erami.: version of a diesel engine. In spite of these 3Chievements, the adiabat~c diesel is not vH ready for .:orumerc ial development. To over- 2,)IDe the teChnological barriers preventing .:om- mer=lal development, DOE created the Heavy-Dutv Transport '''''' hna logy p,'ogram. O!)JECTIVES The ,objective of the Heavy-Outy Transport Technology program is to provide a technological base ior industrv to use in developing advanced heavv-uutv ~ransport ~'~tnes. This program will iocu~ 011 ~dvanced diesel engine technology and will i.nc.lude the investigation ot advaoced =oncepts. ,:omponent changes and improvements to basic "ngine ;.>ncepts, and improved turboconl- pounding or bottoming system technologies re- quired to lIH3.:till,ize el~ine performance and fuel ~conomy. APPROACH Although the planned program approach is to focus on adiab'ltic diesel engine technology for long-haul truclts. this technology is eX,pected to be applicable t.o a wide variety of applications including l!l3rinc. railva)". and pipeline systems. Initial activities will include engine system studies and the beginning of long-lead-time research and technological development. Con- tracts will be let for component and materials technology development and for evaluation of various waste heat utilization concepts. No engine testing is anticlpated in the initial stages of the program. Industry partic ipation in the identification of critical technological barriers is encc,uraged. Initially industry par- ticipation was sought through the use of appli- cations notices. The :::pplicaltions notices provide a notifi- cation of opportunities that may exist within a program area. They ~ontain a "Dear Colleague" letter stating the program area, the approximate level of planned budget, and the persons to -:on- tact. The applications notices also describe ~he program and opportunity areas and the guide- lines for submi$sion of unsoli-:ited proposals. fach ·.nsolicited proposal is revi.ewed and eval- ualed on its own merits and is treated according to prescribed NASA procedures for unsoliciteS _,t ~i".,:nnl)~0~·" [ OOI~~,-"';':;;-;;"'~~"'~ ADVANCED DlSH ENGINi ~A~TE HEAT A£((I'I£IIY --- ----- -'==---- - -==:3: = _____ - --' -=:=-I PIIOJ£CT~ [;OVANCED ENGI1\!] GUPPOIHING R£SEARCj1 ... ,ANAGEIIlfNl 1{(HNOlOGY "NO 1{CHNOlOG y l 1 PRO;{CT CHleE \lAAAG£"~NT II PROGRAM SUPI'QRT l ] v91ICLl SYSTEMS PROGRAM CLOSEOUT . ACTIVITJ(S ------ ---------- ? I 4DIABATlC DlSH 11 TlIIBOtOGY T£ CH'lOl OG Y ? ? HItINE COMPOO!Hl' T£Ofo.:.~.i.0rmt:,nt reclC:led a. mature ~tage ~rJll~)"WlnJ :ne evolutl.Jn of three power tUl'bine .lad. ':;t.~a!- ':raln .JeSlg:1S. 1a 1'178, the ~~~;·...lr'.:.m!;-~L: ::~ =::-'t.'r" ro' :;:U:1sore":: ..1 ~.rogr...un :or , ..>_'I~; r:t.':l'_·:._~:'·;"--" ':t.::,:,_.~._. :'t.'_~::.: •. ~ ,'P- ':.:le :.' ... u .... w- ... ·-.:::>m~A.'un . .i ·,,:;.'ll:l~" ~ '~',-)~~ .):..J.~";t..:::is::..ll ,;()mpl~tl_~!·. of :":lC ?e~':.!.:,-':'e :t.:'::'~ :.~r~-xlr<.l!!'l., 3:: .. H.ivanced ~~rt'oocompo..:.::j i;,.~'se: ~aqlne ;:roqr __ UTt 'N'dS l:11tl.ltC-.j :": . .:. .. " :,.: Impr~""_'e ~:lC tank mlleaqe ''-If :.hl~ : '.J.r:... ...... )_· .. ~:n:'o ...I::d '2n.Ol.:'"'..";:: ::;":' -: ~ .... ")ver the v~Ll...:.:lc :'_'::: ~~:: :;.:.t..=:-. :~:lgl:-:.e :..":"!.tJrovements ,;'.Ju lJ ~t. :-t.'..l~" 2t-,:! ~"." .:.:\,-~rea.s 1:'.":: ::lt~ ,lVa liable t~:'I.t:.'r,-:·.'· :- --::'2 ·;X.;: .. 1~;".:-: L.L'; 1.:' ::--.~ ..... :.lrblne la~- :'_': I .:._. '!:"!'.~": 1::·; ~~iS :"..lr!~!.:-.~ ':t:C:\:1l-1U<::,':; ~! .... to :"'~Fr-;'::::~ ":.:-.t:' :;.r:.....~.,.:TU ..... <'i:.:~c!:":: "_·:!1.:lenC1L>S, ~t:l .... i :::.r~~"...:. .... ~: .... :-:..,:::.e .... ~ :..':-.-11:~t.: ~·.,:=;:t..)rTl 'Jptlrnl'::..l- .. _:: ...... ::ldl v l-:1..1...1i ::3 ::.:;: .l'::ll~!'1ed "'L:. ,. / _. Ji."":l;" .l:: ...• _' ,,)::'1.; ,.y.....i.:~j .----.......J :"-';'.: .... :~j~t-W.ly .1" _·...>Imnl:~s Snq:n.e ::.: ....... -.; ~i7.: ... , iEV>:.:.': . .JP :.h~ :'..l.rbo- ..... _-;c.'~ ··:"'~:;l:'.e. :-~lS .... "':h,l: ... c 1S .1 !'\... .:; :. _~::-,Ator ..r.11_-:: l.S au .... llnented :· ..... r~l:.t.· !:~...].,";.'~. : • ..!:.(-'r~ltt.->d !J':' :::led:";.':; ~f :..~Xhdust. ..:;3.s t:Xpd~l~l::-:~ 1..3 :!"3.:1s!:·etL·~.': ~~"\ t!)e jrtve t.raln ::y :-7lt?C~..l:11_'..ll.:'·.: i't.:'drl:1Q ::1~ ;'-'0'o'l:-:r :.urblne :'0 :!1c !"c ... lr :;: :!It..~ .'!d!l.io;.-:;:~d.t:' Jot. .i. ~·lXC'd. :j;:eed r3.tlcL .-\ :·':".~lj _'OU.~'l!:hl !.:i J.:lllzed to sep- ..lrdt.e ':~:( ... .::-3.:-:I.k5: ....... 1!":. "::JC51"):"'.dl ·:l.;)r...lt.lon from ~he .ll.:~: ~;"''t".'''t'''''d -1~.:-arl:1.'~ .L,J. .. _· ... U--!:'!.:h~ :~rlaf~. r~1e : ~U)0r..l tor':" ~:lQ lnt.?-er t::~ .leve lo;::ment ·:)f t..he t.:J..l':>00.-..--..rn.r-o'.l.o.d '2:'..-lltlc !"i: .. -.acht."'". -:-h~ :"!€'xt ioqlcal eval ... '...Ldt.lon involved ';ertl":':"t:' ~'~r!c'r!'tdn~t! ':t!5t.l:l'-l. Thus, .:~.l:'t$ :::1g.l:1e ~_;mrd!1:,' o;.~:-.,:ercd l:1t.O ..1 231 John L. Hoehne and John R. Werner Cummins Engine Co,. Inc. contract with the Department of EI.ergy in 1978 which called for a comprehensive vehicle test ~valuation to ascertain the viability of the turbocompound engine for trucks and buses of the 1980·s. Within this effort, two turbocompound diesel engines were assembled and dynamometer tested. 30th ~ngines met the California 6 gram ,3S:lOx+BSHC) combined gaseous emissions limit and achieved a minimum fuel consumption of .313 lb/bhp-hr and a value at rated power o,f .323 lb/bhp-hr. These engines were then installed in C lass 'II II (73, 000 GVW) heavy-duty trucks to determine thei.r fuel consumption potent1al dnd Ferformance character i stics. One turbocompound engine powered vehicle was evaluated at the C:.llI>lIIins Pilot Center facility where detailed engine-transmission-vehicle tests were conducted 1:1 a controlled environment. The other engine 'Has ;:>laced in c~mmercial service operati'1g b€- t'Heen !'l~rida and Cal1fornia for 50,000 miles . The results of these tests are re~~rted in the ~ASA cecn:1ical report CR-l5)d~0 and SAL paper :<0. ';1)073. The most salient findi:1g was that t;le !:=bocompounded engines in botn locations 5no· .. "d .l :uel :-onsumption reduction of 15-16, over ~_,e production :-ITC-400 :\orse,r'?wer reter- ~!lCe t:'n~i.ae. ;)uri:1g these tests, a nUlllber of component :nodi!ications were inc<.. .... F.Jrated in the t:.arbo- .... --om;:x:>...t!1J. ~nq~:1e 'oIIIhich r~sulted 1:1 fuel ::01)- 3uroption reductions exceeding the expected b€:Wfl t from turoocompounding alone. T':1rough ;::rev1ous laboratory testing, it; was establish"d tnat. .l ""nefit of 6" reduction 1n fUf?l COn- sumption OVer an equivalent turbocharged and attercooled :-lH engine was achieved 3.10ng the engine's !:orque curve. As the lOdd is reduced, ~he g<>1n reduces in value as the availab I.e ex.haust t'nerqy decreases,. i...isLn.:J :_he~t:: ~c3t resul!:s, the incremental fuel consuc'Ption i.mprovement due to the turbo<.:olllpoundinq alone was ~.~t toO 5.3\ for the lnterim turbocoropound C>llqine, depending upon the terrain or lIIission load factor. The vehicle testing activity described above was conducted with the interim turbo- compound dic,seJ.. The interim nvmenclature is primarily a distinction regarding the develop- ment status of the engine at the time of the vehicle test a<:tivi ty. That is, the vehicle test engines h,ld known aerodynaJnic deficiencies and utilized ~xiified production components to turbocharge the engine. Improvements could be realized by increasing the available energy of the exhaust gas at the turbine inlet, in- corporating cuy-rent aerodynamic design practices into improving the turbomachinery efficlencies, and through refined engine system opt1mization. The combined effects of these improvements were expected to in.;rease the tank mileage by 5\ over the interim tUlCbocompound diesel engines. Therefore, in September of 1980, the Departnlent of Energy extended the contract with Cummins to continue the develoJXllent of an advanced turbocompound diesel eng1ne. The primary objective of th1S program was to improve the tank mileage of the advanced turbocompound diesel engine by 5\ over the interim turbo- compound diesel engine. A five-phase program was established to achieve these goals and enhance the fuel conservation potential of the turbocompound diesel: Task Basellne Performance :1app1ng Task II Engine Performance :'estlng and :.Jpgrading Task III Advanced Engine Preparation Task IV Advanced Engine Dynamometer Testing Task 'J '/115 Analysis Task ~ included engine removal ~rom the Pilot Center test vehicle and installation in a dynamometer test cell to establish baseline data repeatability. Steady-state performance mapping consisting of a matrix of engine speed and load (."Onditions · ... as completed along With measur~ment of gaseous emissions. Tas.k II inc luded an improvement in the fue 1 inj ection system along .... i th flow pa th design changes to the exhaust manlfold to reduce the pumping losses and mi:l1Jnlze the exhaust gas mixing losses. Task III entailed the implementation of existr-ng design practices typically em~loyed in gas turbine power plants into the turbo- compound engl.ne turbomachlnery, englne syst.em optimization, and insulation of the exhaust systEm components. Task. IV was the dynamometer testing of the advancedturbocovl'ound engine developed W Task III. This included performance mapping to assess the perforr~ce achieved against the interim engine performance at equlvalent gaseous emi ss iCon le"els. ~!'!....Y utilized the p<'rfOIl!1ance ~p gen- erated in Task IV as input to CUll'l!!ti.ns· \:ehl.cle mssion Simulation (VMS) computer progrpound engine. These results were, in turn, compared to the reference tank mileage predictions of the interim turbocompound vehicle test engines. TURBOCOMPOUND ENGINE DESCRIPTION The turbocompound engine was developed from the CUIAlIlins NH enqine. The bore and stroke :of the ~H engine are 5.5 and 6.0 inches, respect1ve- ly. The engine lS an inline-sl.x, :our cycle of 8<;5 cubic lnch displacement. fAWl lS supplied to the !'nglne by the CUlllllins PP hlgh pressure injection system. The turbooompound enql.ne was turbocharged, aftercooled. and conventlJ~ ally cooled. A number ~f ~omponent ~ifications nave been made to LlDprove the engine system ,'-er f:or- mance Wlder turbocompoundinq cond~ tlon~. ':':~€'.;:;e lnclude des 19n changes of the camshaft. ':al·:e,;. cylinder head exhaust ports. exhaust manlfo~i. dnd turbocharger. ?rtmarily. tnese modl.flCa- tions were 1nltlated to reduce the blowdown en~rgy losses durl:lg the exhaust ",hase ·)f t"e cycle and too unprove the transm1ssion ef f lC l":;C· ... of the exhaust gas from the cyllnder to the first stage turblne. The turbocompound system consl"ts ·.,f .] radial infl.ow low pressure power turb1ne ::'0 recover the exhaust "las energy. '!'!us. alonq ~lth its ~earlnq ;3r~rl.~g~, :s ~ne J~ ~~r~c S~Pdrate :1'K)dules. 7he mod'J.l.ar ",:oI • ..:e;..:-t..: ".41S selected to t~rovlde for ease of assemblj' .J.nd mal.l:1t.enance.. :"he seL"O!" .. d m...>dule .::;onslst5 ·:Jf ~=-.c :ugh speed gearbox using "lVolute spur :;ear 1:1" r.o achieve part of ~he necessary spt'ed reduct::::c. from the power turb1ne to the craru..shaft. :"...n- rlcation 15 provlded by the enqlne ',)11 5,!st~m and dix'ected by lnternal 011 dr 1111ngs. T::e third module 1S t.he Low speed :rear!XlX Whl'::: completes the speed reductlon req-,llred. ,\ f: .;:i .:cupling is an ~nteqral part ;)f th.l.s :nod'-llc ·"hlCh performs t.he functlon of separatl.:1q :he :'llqh speed :;€ar 1:1"1 from !:he 2r dnj(.~;~.a f ': :.:) L.; l .... "'::a: Vl.o!"atlon. The f: .. -.. heel :10'.151:1g :'5 .lll ~ .A.;":. ~o. : !10US l.ng .:-ons:.r:1cted 0: ';..l~~ !.!'"O:l support. t:tl~ · ... el-Jra . .]f the ~e':lr :'rdl:l. ~l.i 1 !.ncrease 1.:1. e.r.":;l:1e lenqth ':"5 one 1:1'::-• .In..:i :.he entlre system :.5 je.sl.qned sach :":lat .:... ~ :.1..1:. :oe lnstalled 111 "lOst hlgh horsepower englne appli.catlons. The jeslgn ;orovldes for 5~, overspeed .:apabl.llty and :,)0\ :overspeed ;,u1'5: :onta~n.ment. ,.; s;:r:.eroatl~ of :.:~e -:'JtMl!.f'.s "_'J.r!};·· .... "Dmpound .i1.esel ~ng.l.nt! 1S S!10W. 1:1 :-'.l-iV-.rt: ~. The t.~bOcompound enql.ne wa.s rdtcu ... ~!} brake horseprn.rer at 1900 rpl.> englne speed ·.'It.:: :5. ~orque r1se ~o 1440 lb-ft ~t 1300 rpm. ~ lO\:llt;r operat.~nq speed rat l.nq was select.ed ':,\.) take advantage of the low speed torque cndJ':lc- ter lst.lCS of a turbocy.c:cd .... '~s 3.ch.leved w!.t..hout l!1t.:reaslnq ttl€" ~herrMl or structural loading of the reCl.F- rocator. -----------,---------------------------------------------------- " hybrid dlest+-Mt'U"I~ 'i-,stpm ,.. ""Nc"tt gt$ton pc~ ,$ !o~ted Dy • ..... btrI-e CO'tl,t>t '«Ovf!1'eo tr.;tl',.ro,p. ~ .. n.ausl__:::z~::;ti~.1>7 ..... :: Fig. 1 - '::",nm1:15 :m t.!rbocompound ,iiesel enc,ine BASELINE 7ESTIN'~: Tas~. I The inter 1m turoocornpound eng 1:1" ·..,as re- moved from the -'::ununlns ?liot ":·.:.·nter t.est vei1.lcle in Aprll of 1:13U. ThlS e!'1ql!":.e and :he .lSSOClat- ed turbocompcun...:l -lear tral.n '.ere d.1.sasscmbled and examtned fo!' -lllY '.l.r".due or: '..lnusual ',,;ear. Inspectlon revealed t:.i1t :.he :!igh speed gear :~OUS1:i"'; 8J.S:·.1.~.g :~ .. i,j ,~:,:",:: • .:,~ _'.:: :'::t.: :-l'..lh~ ':oJpl- l:.q :-;na.f":. :-::0 :;Ushl:~'; ;:;t:1L:..l!'e ·,,'a:.i ('aUS~~G .;:)'.' t.he f 1 ul...i :':-O:";F.l.l:1Q .:-;ha!t ::x:>ttaninq ln the ie~r houslng D'.!S::l::g bore .!·Je :0 tmproper 3tackup of the shaft !'lUld ::;ouplu:g assemblv. :JlIe to thl.s problem, :: 'N'as jeclded ~o 'Jtxiat~ the test eng- l.ne with .i r-e'/l;3ed t'...lr:JOc:ompow1d q-ear traIn housin.q · .... nl,.::--l ..:,)rrec~cJ. t~lS ~;roblem a.nd also ·ellminated t:X~t:':r:\dl ,,)1;' jrl.lllngs far L.tbrl- ~atlon 0f ~~e Je~rs. ,'ol:,o'oiL--:g :,," C:aTlF1etlc>n .)f ~n'" insta11a- tlOr. of all :-;,t>cc.--;sary .:..ns:.r...unenta~10n, steady- state ~h:;~rfCJrman.:e :naFpl!1g ·..:onslst.ing of a ::latrix of ~nqH1e ::3re~'d klnd l~ad ::on.jl~10ns · .. as .:om- rl~:e~ ~10~q ~l~:l ~~a5~reme~t Jf ~dseous ~"rnlS51..,)r'.S. :\ci-"'eatabll::.-:.·!" ',.;a,:; _'lc!11cved 'Nit~ 3. :neasured ::~!',J.~~ SP£>C .. !l:: :'.ltl .x>nsum~tion lBSE'C) of .32 3 ~!J. bhF-nr at. :.~ ... c _"'3.1: ::-ornla Q gra.m ':oolbl!:ej ~~r:\l.":i-'10rt 1.t!ve ... . . ask. : r ;\ :~~ ...... ':.,3..st. ~~X:"'.d.U.s':. :ttanl.fol.j '.as .Jesl.gned to lmprove t:h~ r'ulse .:-onst?rvat.lon of t::'e 8:xha\lst blo~·dowr.. T:-te ~unct lOns at edch par t connection were ..::h.!Sl":::\OO -:0 m.a.lnta~n 3. :.;on:;t..l.nt a.rea such tIld t the t., ... ,Xhaust ?ump~ng work.. was tn'lnl.mized. 1'!11:> manl.fold Ft"DV1Ced SSFC lltlprOV",,,ents of .,;u3 1b/o::p-nr .It rated ,."'Ower dna a .JuS lb/hhp- hr at tor.:;u~ ?€'e ... as designed to provlje L"nptoVt.'>1,j In]ectlon \"~hdl-act.erl.stlcs 'Ot' the advanc~,l ~·..!r!x>=pound "ngl.ne. The new cam reduced ::.he 11l)ectl.On d,u-atl.on by ).50 crank angle and increased the injection pressure by approximately 3000 psi over the interim base- line cam. The higher injection pressure and resultant shorter duration accelerates the air- fuel mixing rClte. Performance testing at the same emission level resulted in a .002-.003 Ib/ bhp-hr BSFC reduction along the torque curve. At this point. a performance map was gen- erated which showed a BSFC achievement .:>f .318 lb/bhp-hr at rated power •. 307 Ib/bhp-hr at torque peak ~)wer, and a minimum of .305 lb/bhp- hr at 1500 ~&. The fuel map is shown in Figure 2. It should be mbined (BSNOx~BSHC) emission level. The new performance map w.:>s put into C' .. mllluns· ':ehicle Mission Silnulatl.on (VMS) comput- er program to ascertain the tank mileage Unprove- I,"""at over t}le inter Un turbocompoWld engine. The 'MS progra1lt input requirero.ent consists of a detailed description of the vehicle and selection of 'l rO~lte. The l!lOdel is capable of adj listing to varying ,tmbient operating conditions such as te~rature plus prevailing wind velocity and ~rection. The 'lNS can predict both steady-state performance as well as transient engine behav- ior. Output data under steady-state operating conditions includes startability, gradeability, and vehicle performance in all the transmission gears. The route simulation summary includes trip time, average speed, fuel consumption, gear shifts, time spent at full throttle, and average engine load factor. A high degree of confidence in the predic- tive accuracy of the VMS model was achieved by comparing the interim turbocompound vehicle test results with the calculated results of VMS. Therefore, the VMS program was utilized for predicting performance gains of the advanced turbocompound engine. A VMS run was lllade for the Pilot Center fuel economy route at the ccrnpletion of Task II. This route consists of public roads beginning at the Cummins Technical Center in Columbus, Indiana, going south through Louisville, Ken- tucky, turning east to Cincinnati, Ohio. and returning to Columbus. VMS predicted a tank mileage of 5.59 mpg for the upgraied engine versus 5.40 mpg for the interi.m engine. or a 3.5% upgraded turbocompound engine tank mileage i.mprovement. ADVANCED ENGINE PREPARATION: Task III ENGI:-IE SYSTE.'I OPTI~IIZATION - The ""gl:1e cooling system during the ve!licle ~ests ·.lt1l1zed a two-pump. two-circui t cooling system providing a l400 F intake manifold temperature on an 850 day at rated power. A further reduction in intake manifold temperature to 110°c is possible with a chassis mounted air-to··air aftercooling system. A Class VIII truck engine currently in production utilizes this type of cool1ng system. The comparison between eng.lne fuel ,:onsump- tion along the torqge 2Urve fgr in take mCUll fold temperatures of 140 F and 110 C ~s seen in clgure 3. The fuel consumption benefit of ,X~l-.:."'.j Ib/bhp-hr was due to an l:lcr<>ase 1:1 ,ur-fuel ratIOS, result~ng ~a improved ,.:ombus~l()n o:::~fL: ieney. The a.lt'-fuel rat10 c!lanGed ~rom ~4,5 ~o 26.3 at torque pea.'<. power 'h'l~~ 11:..:;J::- :~'~T '''nile the aH"fuel ratlO changed :rom 30.1 c,:, 3J.5 at rated power. Insulation of the exhaust system ~o z·rQvlde increased ava.ilatle exhaust gas ",net'gy to che turbines was evaluated. T~e exter~la.ll '~ . .lrFll~?-.j lnsul ... 'l.tlOn. ..:;ons.l::iteO. Cif an 3.1uro~nd-slj_:..:.3. !-e:l"..l';':- tory fiber bLmket. The alUllll.na-s1llea "klterlal chos8n was suitable for cont.lnuous exposure to ~400 F Ul a normal oXl.dizing atnlOsphere. Insulated versus !lon-lnsulated 0ngl.ne i-"'~r formance testing was =mpleted using ~he bl,~nket to t:xternally insulate the exhaust manlfold, charge air turbine volute. and lnterstage ~uct, The tempera~ure lncrease at the ch,~rge a.lr ':.u,- blne was 10 F wh.l.le the go",er curblne inlet showed an l.nel.·ease of 15 F. 1'I11s was due to the cUlIIulative effect ,:,f heat loss rectuct.lo!l over the exhallst man.l.fold, charqe a.lr turbl.ne and lnterstage duct. The lncrease in exhaust gas enthalpy provided a reduction in fuel con- sumption of approximately .002 lb/bhp-hr along the engine's torque curve. The fuel con3umption for the turbocompound engine is shown in Figure 4 for the insulated and non-insulated config- urations. ~1~~. __ ~ ____ ~ ____ ~ __ ~ ____ ~ ____ ~ t300 '.&00 1500 1600 1700 1800 '900 E __ _ :ig. 3 - intake manifold temperature comparlson torque curve: BSFC vs. engine speed 300 '300 " :''.1. 4 - TCPD - 450 per fOrmculce da ta: :nsulat",: ·/s. non-insulated exhaust system FlU,::; l'aIiER n.'RBI:..; ~',:· ... 't.:r :·...:.r.:Ju'.e ',;as ;:erfor;J,c.J 'J,slnq :.:-:.e .; .. :unt." :.:.;!:bl::t." ',·(.'l;j:e. t·..trb1:1t:: rot.or load ..:ornpreSSO.f, _~.,)::".!,-::.cr, a:1,J. r.:)~,-"'r :0 .sr.:roud :;learances. ,; ;:;;.l,f,\,.r:ldry ~; ::le fri.:::-tlvIl ':..)55 (..is ::neasured by :l(!at reJL~c~l':-:: ':..) :.;:~ ,)11) _!.:lta 15 Jepicted 1:1 ,-i~~r~~. A ;r~p~. ·f :~e :)dl: ~~ar!:~~ versus J.:>u.rr:a.";' 2(,;'.3.1"1:'.:::; ::;0:;>...:::.3.:;123.1 ...:':·i':'':':'t.!:l(:/· :..,S ~:tC""1: in F19ure -;. :-'l~Urt2' e also shows ~::-te pal·3,Slti:.:: loss In :10rscpo .... el· ,)f t:-te Journal ~~arl:1g and the ball bearln~ :..tnit .It :-3tt?d ..lnd t..orl,'J.e peak speeds. ThlS 3.1 fference ·.i;l horsef-)Qwer !.s ava~l dbl e 3.5 sha f t E=-xT.er ! or the ~n~ lne .. ::''..ll'!.il.cl." !..est.l.nq '''''dS :'0 :lave .::.:>ecl1 ...:arr led out to evaluate ::-te -.]dl!lS frau r~J.ucvd J!-"'€r .. 1.tlng clearances ntdde ~"'l')sslble by ::' ..~ ~dll bedrl.ng syst.em, no-Never. ~ench test.l.ng lndlcated 't..:.rlat. the shaft ='~!~:::("ss '~d.S :~0t suffi=1.ent ':0 .lvold it flexUZ'al ::to:::jt.~.. :::lS :YP'C ~'f :noC1011 ·-"l)u.i..j :lot allow an ~v .. l.L,;.a~l,.""Il1 ~t ~~lt:' :Llll =>edrl~1q f-"I()'to/er turbine .... ith re<:l.'.lC:t to improve the aerodynamic efficiency of the powe:c turbine, an inc>:ease in operating speed was requi>:ed. This was accomplished by varying the gear >:atio with resultant Ghanges in the operating line of the turbine shown in Figu>:e 8. The interim turbocompou~d powe>: tur- bine ope>:ated at a gear ratio of 15.78 times the engine speed. Operating lines are shown for eng ine speeds of 1900 and 1300 RPM at three 'lear ra~ios: 15.:8, 16.~2 and 17.:: ':eimes the engine speed. At 1')00 RP~I, as t.he gear ratio is in- creased the power tu>:bine efficiency remains relatively constant at full load, but decreases slightly at part loads. At 1300 RPM, however, the power turbine efficie!'lcy ~mproves signifi- cantly over the ful~ operating range. Hardware · .. as procured to increase the gear r. t.10 ~o 16.·12 a!'ld 17.12 times the en9ine speed. ~ sor 4sf ~ I ::! I ~ 401 • _,r""'~ E··" ..... ,.. !T -'3) ,~ '~. v 2sL-------.'--_____ ~ .... _______ _ 10 '5 20 25 30 35 40 45 50 Cornu:ted Rotof Speod (RP9dl 1!. 1000) ~~i,-~. j -- ~adial power tltrbine efficiency map :::n.gtne performance tests were completed wit.!1. .1:1 ~hree"eaar ratios throughout a :natrix of eng"", speed and load -::onditions. The ~nter ~ediate rat~o of 16.~2 was selected as the opti- ~\Ull\ rat.i.o after c valuation of the full and part load !I..lei consumpt ion data S~lOwn tn F iqure ~ and Fiqure 1-:1. An average fuel consumpt~on "enefu: of .J-Jl lb/bhp-ht' ... as measUl.'ed along the tOl:que curve over the ~nterij gear ratio 236 of 15.78. This is consistent with the preQ.~ted· benefits at full load using the improved effic- iencies shown in Figure 8 . i , "- :r: I:" 15.78 Gear Ratio ) 16.42 Gear Ratio :.J 17.12 Gear Ratio ~.31 () u.. CIl !Xl .30 300~~·~~~,~~~~-~~--~-~--~,----- 1300 1400 1500 1600 1700 1800 1900 Eng.ne Speed (RPM) Flg. 3 - ~ear ratiO optimlzatlo~ ~~r~~2 C~r\'L: 5SFC '/s. eng ine speed 34 33 :. "30 ~ . .., g325 320 315 - , :J - i :~c - ~ " 30, "~ ::; 315 a. ~ 31 ~ '" 305 300'-- "'15.78 Gear Rat,,· .16.42 Gear RallO 111712 Gear RallO 7'J0 JOO • '.:'0 : y=,C 'sec Eng.ne T')'''l,t' (Ft-Los) ABRADABLE SHROLUS - As stated previously, Task III involved implen~nting practices and techniques typically employed in gas turbine power plants into the tl1.rbocompound engine turbomachinery. One of these practices for increased efficiency levels is the utilization of abradable materials 1.n order to reduce clearances between the rotor and shroud. An abradable nichrome/polj'ester composite coating was applied to che charge air turbine shroud. The nichrome/polyester coating has a ten'perature capability of 1500°,. The abradable turbine s! ')ud was initi.ally evaluated on the engine. Performa,1ce testing ·",as completed for the abradable versus baseline turb ine 5hrouds. The cold clearance for t:he turbines evaluated are shown below: Axial Clearance "adlal '.:learance Baseline .030 .010 Abradable .Jl5 (:hnimum) Test data along the torque curve jid :lot indi- cate any fue i consumption advantage for the abradable tUL"bine 5hroud. Bench testing was !3ubsequentl,' completed to more accurately quantify the effect of cleara:1ces on turbine efficiency. Two turbine volutes were evaluated: a baseline shroud ,nth no abradable coating and t!lc t:.!Xbl;",;·2 ..;:':.rc·-l ... l · .... it~l :':10 a.b!-,ldable nichrome/pol yester C':)dt.l:".g. .;',,(101 ..:learan::c.s ':l~O the abradable :::;ilroud .... ·ere '/ar led from . J27 inch to .010 inch "..,i th !nlnimal radial clearance. The baseline turb~:-:e 3hroud axial -1:1d radi.al clearances ·.,;e.r0 ':;02: .:it .~1~7 i:1Ct; :.i:ld .:)1,) i ... ..::h, respectively_ :'! ... e ~e!lc:l +:~5~ ~~.:-:;ul':5 3rt,; sununar i zed as fol 1.. .. )',.';:3: Baseline Build Build Build . .\ .-~"{ial ::learanCt) ----_.- .C':: :-':3. ___ iial .::..c!" 3.]2.:)18 -.: :'t.?arar,,':·2 _' ::::-:.:'.)'"ll' - J. " :,,0 .. ::.=-:l.."':l.t:.::'.. >2:::; >~::'.l~":\llln , ,. ~ '~ U~ 1::llL,"r. 0:5 ·:'·.lrDlne Ef:icienc':{ 79 <3 , ) - " SJ 5 :30 3 7he iliradable .:::argc- 3.1r ':U!"bl:'.~ ~:lr-::>ud contom" L5 sho...,.:! 1:: :~:.,;'.;.re :1 ..lft~r "~:1e Denc:l tests. :-:te 't.:.J.rbl::e ;::-:::":l.en..:y ':e!".3".J.5 rotor Flgure :.2. ':'a;c!.ny :.:-:.~ ___ ) ~l";':"::'J,.:l~ "_e:;;~ .:3tclnd accur:'acy 3...~d repe.3.taoilit::, ':~c a.bradable tur- bine shroud s~c·.,.ed :~c· Jiff~re:~ce 1tl .. ~fficien.::y ... -hen ~he aXlal ..::ir2'ara .. n.cc #!I'as rcci'.lced ~rom • v..;. I to .J10". :{owever, . ~':"'e iata l!'!dlca.tes .i sllqnt g,,'\ln in :~rbl:h= effiCl.e::..:y j'..lc ~) ::'It.:' :..) .... ·eri:lg of :h~ radial .... ~.learMlce. ':-~lS :u:.provement 1.:\ perfor- :na.nce .. ::)1:' t~llS Far:'lC'..ll .. 'lr :'..:.:rb~ne, :.:an be tx:aced to ~!le !.:tct ::la: .. \ :::~J:l'.-:'~C!1 :.:1 !·adl.ll cle ___ 'll:anc~s reduC€s :~i.e bl..lJ.~ :0 ~la.je It:'akage in !...he .. 1.rea · ... tlt:~r~ .1 :.l.r,1'2 ~'0r: .:..on ,,)f t:le 'otiork. tS bel:1\j .:one. 237 (jJ >- # >- - - - w :; >- 85 8 ~5 +BAS£LlNE .027 AXIAL ".018 AXIAL BOlO AXIAL 55~~ _____ ~_---z. 30 40 50 60 70 80 Corrected Rot(J( Speed (RPM • '000) :19 ~ 1':: - 1",.u:-bl.ne ai)raddble snroud DcnC:1 :t~S t - ?ressure ratio 2.2 .>.BRADABLE 2Q:-!Pr..ESSGl'. "HRV::D - ;'or :.:.e ,,,",,,- rressor shroud. an alum1nuro~raphlte C0m~~hl:~ :oatl~g ·"as eV31Udt.~d as thlS :ttatecldl :5 .c-:c- ;Odtlble with an al\.lrf'..:-rmance ~alns of ':ne ,ldvd.;·, . ;ed ·.:::';'1:"'.E': ?edesl~~ed ~,~ l:1C.'-': .i:..lfI'\(":er ~;ulse --.:xhaust :"1.dfll::>li ~~ew l:--.:t~ctor :~l:ns:~af~" i:J:.X' ·~lt:--. l.u.prl'),leJ. lnl~C~l~r ~:~lrl~:~rl~tl.:~; Ir.'::)'Jld:·~(! ~·xr...l..ls':. :":1.l:afC".:'l:i, .":. ir~;~· d.j r '_·.lrDlti.t.' '.";;.'J,!:"t:. i:".d l:."t:!-";-_l'-;·-' 1.1 .. .::)lmi..ll'-l:L ..... j a.!r-':~,-dlr lf~t.>r':·.'f::-ll:~'_. {.Ll.·" r:,!T) Slmuidt.ed ball :)earUh; ':".:.:;t.t?m for _ .. t.: :.:,ower t.'.J["C 1.:.(' -":pt.L-nu...'1l ?G1",,'er :.· . u:CL".~ v'ar '!-.J.tl..J Abr.1J.dbl'2 :·.:r.lFres.-;or S~~!" -:~J .... 1 :':--. ;~ SmlSS:0:':::;- ',oIt.. r~\ ":C-l::U:>_'.j .1:::.1:-':'; :::e .. :-r.,(),k qaseous ~mls:::::..on : .. :,-~.~ ':.'-~ ,,'t.~r:.:".: ~_~".at. ":.:>_ .. ':~:'" was oper.'l.t:':'q 3.t. :::t: _·Jr."\.f.'~!~L>;j " ..:r.1::-. :1....'VP.!.. . . ; i3-mode 3S:i:2x ~: :::; '::::~.-~:~~ l.:'. i 3:)i1C _2-: ..;m/b!~p-:.!" · .... as ::'~ds'--;,r.,:·j .It: ~ ~ .". _'-. i·.·~:~i:r;:_ "" ... i':::' ~' .• : • '; ':_" :.3::.;';' ::',i. ::.'_Li,. :":.:"C!":~, :·..:.rn ........ ·x;.\t-'v"....l::c. ·-':::S:'::c ..... "_~'.'t.. :~L'"7"Ie ·:':..~:-.l::':':"'·':: .u~i ':;!.::l'.J.l.'I.':.l::":: '::~e ....... ~_-i..;t": ;"'V~;:,-i. t2'::-l:.::,_' ".:::.:.~. :::'2 :..::t.e!'l~ ~'J.rc()COl' .. tJOi..ll1.d r'!"edlC~1....',j :..i: .. "- :-':~~~3.~o:"'! :"::tr.L·")V':·;'le:~t ;:)f ().s~ ".-'.3.~ .;ic!1.1.eved. :-:-:':.~ ::'!"'>i:.:..;t...".j "" ::..:..e~ .:-,dV!:1QS f,.)t '::.:.l -jallons '::-Vt.!>t- :::t! .::~:~~:..l~t2d _:"~:.:"'1 ~lle .;ou.rs~. A ':!15 ,:c-::-:.;.. .... J.l~:.. .3 .... ,:". ,,'a~ .1':":::;0 :;!._ldt.:' ~ or -:ae lnto.::>rlm ~:urboccmi_'()''':'::-.i ::"t2Li :.~st I"Jut.e :rcm F'lor Ida. ~I.) ;",.~al;.. !()l::~ 1.1. 7:-~e :;out;;.ern rOLlte across the ·_·nl.:'t2d St.;tt'2;i ':'!1c':'-...:.d.es .;;;ectlons of :-75. I-1J. I-~O 3.Ild :'~d_ :'~11S !"0;..tte, :3~0'W11 1:\ Figurl~ 18,. prov1..:ireS ~1 ·l~~..r;.·,~~~ .. :)f :~rL.lln:i :.nc1;;.d.lng plans. roll t::g "-.ll: s. 3.nd mounta~;t0Us 'lrades. The v'~tS pred.l..:t.l\,)nS ..lr~ s,hOWh In T3..ble '::". 1':le 239 ad'lan<.:ed eng1ne .lC;lleved tank m~leage impro'le- me!"",ts 'jf 6.-) and 6_1 ;.'ercent 0ver the lnterlm ",:";~n" at max~mum cru~se "peeds of 60 :nph and .;) "'ph. ~espund r ::.~: ~PH} .·H:~:' :3t=:-:=::.:. ,:'xH} :'A5':'~~ :'.!...s ... ; --: .. ; ,':' : ...... '.A~y . . ..... - ... :' .. =- -:-~ • . ;:::··:.;:-~c==:~ -: .... :::.--+~; ." ~~~:ER!~ :'\.·r·::·-~S p ,'.".;~ ."-:'" -4--' .--: ..-:.::.-c:...-. +'~:-.:'-~:.-.~~:-+---..::.-.~-:.::..:-.. ·...-L-~~=--~~-~~-:::.~: ~~~:, i ,_ . ., .. , .. _ .. ___ --.. ~---..... --------...-.. _----+---_ ... _-_. : ..... ~ :. .. ; '::' .:::::-:: .~:-~: ..:::. :.: ~ . - . - '.' .' .. ··tr:: ___ " ____ ". -.. ----__ - ____ ~_J ___ .S~_ ! 24() -_.'-' -----... _-------------------------- TABLE 3. VMS DATA SUM/-!ARY FOR VARIOUS TERRAINS ADVANCED TCPD-45C VS. INTERIM TCPD-450 \ ADVANCED TCPD TANK ~ILEAGE ROUTE ENGINE TA.,''IK ~ILEAGE IMPROVEMENT (MPG) LEVEL INTERIM 6.17 INTERSTATE ADVANCED 6.60 7.0 ROlLING INTERIM 6.20 PLAINS ADVANCED 6.62 6.8 .2 PERCENT ,,'P I INTERIM 5.66 INTERSTATE ADVANCED 6.05 6.3 -- HIlLY INTERIX 5.99 INTERSTATE ADVANCED 6.39 6.7 r- XOUNTAIN INTERIM 5.20 PASS ADVANCED S.52 6.2 L..._ INP~7 CONDITIONS: 18 HP ACCESSORIES, ~EARED SPEED = 66 MPH, RADIAL PLY TIRES, 73,000 LB ~W, dSo:, STILL AIR SUHHARY The pr 1.l1\ary ',)0.; tC~ l'b~ .J! :':h::' 3.u.vdr:",-L',i :Jrbo- compound jiesel t2nq .l::e :--coqr d.ITI .... 'as t.o imprOVe ::lC tank mileage by ,), ::Jver t;,e 1-)01) '/eh,::: le :est (inter im) turbocompound diesel eng laes. 7he technical approaches used to -ievelop the advanc- ed turbocompowld enq lne ·"ere: I. Inc::.-ease ~he ~'.J~bUh.· elva llable enerqy ln the exhaus t ",as '".'l t.h 3. ~ore ,= f f lC leO t exhaust :aanlfol.:l dnd by In::)ulatl:1~ :he exhau'::3 t '-:;'!$ t~m comI--)()nen t.s ~ II. :mprove :.:"!.c ::J.el 1:11ectlon ..:hardcter- lstl~S ~y ~~r~vljl~g ::l'l~~~r ;'rc5s~res 3::J jnor~.er !~rdtl~~s. I I I. Improve :.:H~ :'Jr.D<...),.:omF)(·"r..1::J. .c)'!"S ~em Dr .Jptlml~1:1q t..h.~ Fo;.;,:::r :'J.rOl:~t..' s;;eed :or max ltllUJU ::..lrDl::C L'! ~ 1 ..... · Leney ,lnd ::Jy r-educlaq t.'lL> :urDl:le ',::dr~ !.JearU1.q :o.cchanlcai :'~S.::iCS. :~2""er '::-:~~ l.:: ':..i.i-;.e .) :~a:"'. 1. - , .... 1 j ':.emrer a t '...ll-t..~ :.:: r- t~\ i ''';' .. : t! :~ 1 :. r ;, '- ,)XL::ie t"'>fiIL.:>Slons, .l.n .. J. :.: .. ..:.:~d:ie t'uql:1e ':.~ermdl '.~ f f 1": l~ncy . \'. lmpl~ove !::1t.J ":'v·'(llprt.:.'ssur eifl .... ·l~n....:y l-':~ by rt......z1UC1!lG :::e J~~er~-ltlnq .:It::'dr-lnct"s • 1 t.:t ...lll .lOr 3.J.aD 1 02' ;;:lrcuJ... 241 :-:le ...:ombl.ned ,=ffect.. of these l.mprovement.5 result.ed La a rated ?Ower BSFC of .31) ~D/ni1p-nc '''1 th a minlmUll\ BSK of .298 lb/bhp-hr · .. hile meeting the California 6 gram (BSNOx • BSHC) gaseous emission level. The advanced engine performance map was rut lnt.o Cummins' ':ehlcle :-tission Simulation (';~) !,coqram to 1)ced1Ct: the tank :ni leage over :11e CUlI11111ns' P 1. lot CeI:ter fuel economy rotlte for ::omparison to t:he Interim engines. In t~e course vf the veh~cle testing program completed In 1)80, It was proven tnat. an exceller.t correlation eXists between '/~ predlcted fllcl consumpt1c;1 - .lnd .lctual '1eil.lcle test results. Pie '::-lS :'alcu- :atlons predicl:ed d tank 'lllleaq,> ::Jf :;.7) "'pq ~~or the ddvanced turboccrr.fXlund eng Iut- 'Nt"- lie '::tt' lnterlm turbocompoWld englne prediction ·"as ~ .~.; "'pq. Thus, a predicted' anl< :nlleage improvement ...)f 6.)~ was achl.eved "lllL"1 t..he advanced turoo- ~or.lpoc:.nd diesel eng1ne. :ll summat10n, t.he advanced turbocompowld j1esel t.agine program n~t and exceeded all tank ;,ileaqe ~oals, f'JIther ~"'nha'nclnQ the pote~~!aJ.. :.J.cl ... -onsumptlon 5.C\Vlnq.::i- 0t ~he t.i.lrbocompou."'\J. 11"sel eng1ne. 1'he turoocompotUld engine provldes ~ apportunity for the f~ture by offer~ng In- c:reased thermal efiic1ency, reduced exhaust t.;!!lllSSl.Ons. and improved drlveability ,.,h11e rualn- tal:nnq pLesent standards of durabilit;.y • ----~--------... -----------------.------------~~--------------------------------------------------------------- Status Report on [)iesel Organic Rankine Compound Engine for Long Haul Trucks ~~T ,- Among the efforts in this yea I:' sTruck Bot- I toming Cycle Program was the installation and , testing of an orgd through substitution of small trucks for larger ones (e.g., Class 7 for Class 8), using lower powered engines. some measurable improvements in ",ngine efficiency. and the more widespread use of energy saving options such as fan clutches, wind Midtlll'll D. Koplow. Luco R. DiNanIlO. and Francis A. DiBella Thermo Electron Corp. deflectors. and radial tires. Overall. the fuel saving improvements in heavy-duty transport are less - both proportionately and abSOlutely - than in the automotive sector. It has been projected by DOE that by mid-decade the aggregate fuel con- sumption of trll<·..s and other heavy-duty vehic les will exceed tt.a~ of automobiles. Fuel efficien.::y i~provement is more difficult with trucks than automobiles because it is largely prime mover efficiency improvements that are needed, and these are difficult to accomplish. The Truck Bottoming Cycle System. ,.dth a projected fuel savings of 15 percent. represents the largest single gain in prime mover efficiency available for long-haul trucks .. One area of diesel engine research that holds substantial promise for efficiency gain" is the development of an uncooled (adiabatic) diesel en- gine. It is noted that the potential for waste heat recovery with an Organic Rankine Bottoming Cycle System from this more efficient engine is even greater than with a conventional diesel engine. Domestic petroleum consumption is off slurplv irom the peak of 1978 when imports reached 8 ",ii-' 1 ion barre Is per day. Current ly we .ue averagin,; imports of under 5 million barrels per day. This reduction in petroleum usage is due mostly t" r,,-- duced automobile fuel consumption coupled with the depressed state ,;'If the Sati0nal ~~on()my .inJ the increased cost vi fuel since the days oi pea~ consumptlon. The oil glut we ~re now experienc- ing is also a product oi the depressed world economy. One factor that has remained unchanged over the last decade is the dependence of the tr~ns portat ion sector on petroleum f ue Is. So ec,)\\om- ically viable suhstitutes for petroleum show ~uch promise. Thus, While the present petroleum sup- ply picture is bright and prices are stable. there is little reason to be complacent about the longer vie~l. The price of this deplet ing energy resource will inevitably rise. Efforts to reduce petroleum consumption are still very much in the Sational interest. Our work in this program has applied ad- vanced organi.c Rankine-cycle technology to mobile diesel enginE' waste heat recovery and has carried the developmEmt of the Bottoming Cycle System from concept to complete operational hardware. We have two roadworthy Bottoming Cycle System equipped vehicles, both of which have demonstrat- ed more than 12 percent fuel savings in actual highway tests. In previous years we demonstrat- ed the technological feasi!:!.~!.ty of the Truck BottoMing Cye Ie System. [n the current program we have made improvements, refinements. and mod- ifications to the system components to gain in- creased performance, better reliability. and re- duced maintenance - efforts directed at the ex- pressed concerns of the truck industry that a Bottoming Cycle System must be as reliable. main- tenance free. and easy to ,)perate dS the diesel engine it se if . A iull description of the work accomplished in the past year is given in the following sec- tions of this paper. SYSTE:-I DESCRIPTION Operation of the bottoming cycle is outlined in the system flow schematic shown in Figure 1. Hot exhaust gas. at approximately 950°F at full power 3nd speed 0i ~IOO ~pm. passes through, vape'r generxp,mds through this small Single-stage turbine, delivering ddditional power to the engine output shaft through a set of reduLtion gears. After partial cooling in the regenerator, where some 'Jf the useful energy remaining in the turbine exhaust "apor is r~covered, t.he remain- ing low-grade reat in the working fluid is trans- ferred to c"oling water in the condenser. ~aste heat io< rej~cted to the atmosphere by means of a ~eparate radiator Cafe mounted integrally with :he diesel engine ''''c,lant r3,ii.ator. Th~ fe~dpump then pumps the condensed working fluld t.hr-ough the liquid side of the regenerator, where the Fluorinol regf the cycle heat. beiot'e it once again enters the vapor iener3tor, com- pleting the cycle. In the current truck bottoming cycle system. waste heat is extrac~ed from the exhaust of a standard ~85 horsepower turbocharged dnd inter- cooled fOUl stt'oke diesel engine (~ack ~o-del ENDT676). The bottoming cycle system package in- corporates all components of the organic fluid loop into t.1lO subsystems: the power conversion unit (including the turbine. gearbolt. feedpump, and integr.llted condenser-regeneratur) and" vapor genel'ator module. The third module fot· cooling functions consists of the fan and com- pound radiator and has only water connections to the organic fluid system. This packaging ar- ranget'lent alllows the organic fluid system to be located ent.irely at the rear of the diesel engine. POWER CONVERSION L~IT (PCU) - Arrangement of the PCU components is shown in Figure 2. This PCU, which includes the turbine, gearbox, feed- pump, and integrated condenser-regenerator, is packaged around a power take-off unit that has been designed and fabricated specifically for the Bottoming Cycle System to facilitate integrat.on of the system. Shaft power is produced by a S-inch-diameter, single-stage, partial admiSSion, axial impulse turbine. Five nozzles with a 7.5 to 1 expansi~n ratio deliver organic vapor to the turbine wheei and the turbine power is delivered to the diesel engine output shaft through a 17.7 to I gear ratio. Pressurization and circulatLon of the organic fluid is accomplished by a specially designed three cylinder radial piston feedpump driven at engine speed. The working fluid flo\i rate is ad- justed to engine load by varying the stroke (and hence the displacement) of the feedpump. The con- denser. "hich is a water-cooled plate-fin heat exchanget', and the regenerator are combined in a single integrated unit. co~rROL SYSTE~ - The bottoming cycle control "ystem shown in Figure 3 maintains proper temper- dtures and pressures in the organic working fluid as the speed and power of the diesel engine are varied in response to driving conditions. Flow rate of the e'rgc- ie fluid is maintained in constant propart ion to i ue I flow rate in the diesel engine fuel injectors. This simple open- loop ~ontroller is augmented by two additive ~losed-Ioop error signals. One signal is propor- tional to the difference between actual turbine inlet temperature and the design point tempera- ture. The second error signal, based on the rate of change of turbine inlet temperature, prevents instabilities that would otherwise occur- due to thermal delays. Engine ruel flow is proportional to the prod- uct of engine speed ,llld the engine injection pump ra~k position (i.e., driver's throttle setting). Engine tests have shown that fuel fl,.w rate is dlso proportional to ~ompressor Jischarge pres- SUL'e at the turbocharger. dnd this signal is :nore convenient to apply in the actual control system. The working fluid flow ratei:> proporthmal to the product of {eedpump speed and ieedpump dis- placement. Since the feedpump is driven at a fixed ratio to engine speed, feecipump displace- :nellt is :nade proportional cO ~ol1lpressor Jis..:harge pressure divided by engine speed, with the ddded corre,:tiolt signals. WORK EFFORTS AND ACCOMPLlSHHENrS During the past year, Thermo Electron Corpo- ration has .ade significant progress in the d~ velopment of the Truck Bottollling Cycle System. Work efforts were directed towards the following major task areas. • Working Fluid Studies - The goal of this task is to study and develcp 2ethods that enhance trouble-free operation of a Rankine-cycle system with the use of tbe Fluorinol organic working fluid. • Vapor-Generat"r Development - The objec- tive of this task is to stu<1y. eval'Jate. and gather data through tests that will lead to the development of a compact ';apor-generator heat exchanger with long-term heat transfer effectiveness and mechanical integrity. • Control System Development System efficiency optimization Working fluid throttle ~'alve This task emphasizes the development of a control system that optimizes the Bot- toming Cycle System performance across the widest applicable range of operating parameter:,. The specific ,~fforts and advances made in the above work areas are described in the follow- ing sections. WORKING FLUID STL~IES - ~easurements of the formation of decompositiop. products are being ~ade by testing under controlled conditions; methods dre being developed for the removal vf these decomposition products from the working fluid. Fluorinol. The initial part of this program task was the construction of a dynamic test loop to meas- ure the formation of decomposition products with ~ubse~uent development vf a method to remove the decompositivn products from the working fluid. The dYn~~i.L luop :;ho .. 'U in Fiburl;! :, (:unsi$ts \.)i .i boile:r, pump 9 expansivn ·;d.ivc, ~ondenser .. and re- lated hardware. The fluid loop incorporates the fvllowing features. • A leak tight system for contamination- free operation. • System cvntrols ivr continuous <.tOd Ivng- terill stable o~eration of the ioop with minimum attention. • Ihe lovp incorporates features that S l!J.ul .. te c",:-Jit il..lr.s Cnc\)w-It~::-,,-·d. in th~ iruck Bottoming Cycle System. Ii» The lvop is instrumented to measure i-:e" tt:!IUperaturt!s~ prt!ssur~s, ,lnd :luid fll....~w ,[dtt1. Rativn,ile - Althou~h working fluid in\'ent<.'ry ,10d (:unJit i~-n-have been dULUl.lh.~nt~ci in pri0r ":0m- ;>0und en!1ine syst~m testing \i.e .• 1000-hour en- Juranc~ t~sts), the tests were not g~ar~d for ~L'ntrolled Fluorinol working fluid tests. The f.luid was subject~d to transient temp "f Iwrking iluid tv the cLluditivuS that arc eucounte~",d in operating ~ystems so that the fluid can be chemically exa!1l.ined and its de- ~<.'I)lpositiol\ rate ascertained. rile idea vf the :,10P is to ex~>ose the f lui.d ~" very prescribed ",nditious over fi.xed periods vi time. and chem- lC<111y measure any chang"$ in the fluid ~,>mposition. The fluid <:irculating loop is designed to expose the working fluid to the operating condi- tions so that time at high temperature and pres- sure and the number of cycles which the fluid is put through are maximized. Test Results - In order to ensure that the Fluorinol-85 (Fl-85) wetted su['faces we.re contam-· inant ft·ee. an initial cleaning procedure was followed. Prior to starting the tests. the loop was first cold rinsed With Fl-85 for I hour. The loop was then charged vith a 2500--ml inventory of FI-85 and put through a ~-hour shakedown run at fluid conditions of 5S0·F and 500 psia. After cooling. the working fluid was drained out. the loop was pumped down and a virgin 2500-01 inven- tory of Fl-85 was added for the start .jf the. lOGO-hour test. The test ~eries were performed vn the Fl-85 at the baseline conditions vf 550°F and 500 psid at the inlet vf the expansion valve which simu- lates the turbine in this loop. A total ,)1 1600 hours were rw} in the two separate tests With approximately 600 hours dccunlulated during the first baseline series before this test had to be aborted. and :l full 1000 hours accumulal"d during the second baseline test series. The initial haseli ... e test was terminated after 587 hours of oper~tion due to excessiv", loss "f the working flu1J inventory through .• titting in the sampling ~ystem. F,)llowing the repair of the leak. the system was again ~harbed with ~500 ml oi virgin fl-85 and the second series 0i tests was started. The second t~st series was run i~r th~ planned 1000 hour~. !.luring both series •. >f tests. liquid and gas samples were t',"-en with the liquid sd.~oles dnalyz~d f,"'!" ~":.ldity icvel. t'lgurc S shows :.~~.-: ~~ ... i..t.l level ~lS a tunctiI.Jo 0! running time fvr both tests peri0r.aed. The neutraliza- tiv!) number "f each liquiJ sample is "l,~tted ",s d data point in this figure. The neutralizdt i0n :Hlnb..:r is ..in indicdtL)n Jt ..l iluiJ's d~idity, cx- "ressed ~n mi lligr'ams <.>i ?otassiU!1\ hydr,'xiJc nec- ~SS,H·:-· tl..) neutralize l bLlIIl \Jt" th\! i tuiJ ~~l:nplc~ fhe ::lethvdoh>gy fo11ow\.'<1 is thdt ,jes..:ri.l>ed in .-\S'P.'t :<{ethod ::>97:.-6". :>eutrali7.dtion ~urnb.,r bv \:0b .. "\r-J.?1di(' .... ttIJI' Iitratil....'n. ['he;;! ..ll~dwab:c:':· d...:id :to!vel tor Fl-8.=t in d Ranunt!-t.:l~l~ syst .... ---m Q(!tcr- mineop materials the neutralization number decreases and react~s an ~uilibrium condition. ------.-.--------------.-... ----... ------.... --...... --~----------------~---------------------------------------- At 748 hours the loop shut itself down due to an electric'll circuit interruption. When the unit shuts doWtl, the condenser pressure drops to the vapor pressure of the Fl-85 at room tempera- ture which is approximately 1.3 psia. Some leak- age of air apparently occurred during the down- time because after restart, the sample neutrali- zation number at 755 hours showed an increase from 0.013 at the 635-hour mark to 0.023 showing the second peak in Figure 5. The neutralization number dropped to 0.013 at 815 hours and remained low at 932 hours at a value of 0.014. Following a scheduled shutdown at 929 hours, there was a third peak in acid level with a subsequent down- trend at the end of the 100G-hour test. Gas chromatographic analysis was perfor.med on the virgin FI-85 prior to the start of the test and again on the final lOOO-hour sample. The analysis shown in Figure 6 indicates that no major degradation products were formed. Also, the figure shows that the working fluid essen- tially remained at the proper fluorinol-water mixture changing from Fl-85 (prior run sample) to only Fl-83.5 at the 1000-hour mark. This change is due to the "pumping-off" which acts as a distillation process, removing the trifluoro- ethanol with it's higher vapor pressure at a faster rate than the water. Another s.eries of tests have begun with the working fluid dt an operating condition of 600"F. \'APOR GDiERATOR DEVELOP~IENT - Work efforts on tbis task Oire being directed toward effective- ness improvem"nt of the Bottoming Cycle System vapor generator through deSign modifications and testing in the system dynamometer facilities. ~!ore than 200 hours of test ing have been performed on the present vapor generator (VGll). These tests included the verification of fouling characteristics of the heat exchanger and the effectiveness of a soot cleaning scheme. The othe1: major effort in this program phase is the design., f:1brication. :1nd testing of :1 new vapor gener:1tor (VGIlI). This heat exchanger has been jesigned and is now being fabricated. V~r Generator (VGIl) Tests - The init ial work in ttli~l:ask ~0nsist~~esting the pres- ent vapor gen.erator (VGIl) in the system dyna- ~'meter facillties as sho~~ in Figure 7. The ,,'Gll core shOlm in Figure 8 cl)nsists of 14 f inned- tube coils. each 22 feet in length and assembled into .l cylindrical package 17 inches in diameter by .. 8 inch"s in height. Th" .::oils .lre connected. both on the inside and outside core diameters. to furm. a single ot'ganic fluid circuit. This vapor generator a 1so has added insulat ion and improved shrouding bet' ... een the outside portion of the core dnd surrounding shroud to prevent exhaust gas bypass. A set of laboratory diesel-ORCS engine tests were initiated to quantify the alllOlmt of diesel soot fouling in the vapor generator and to test any soot cleaning mechanisms that were thought to be effective. particularly for the truck's waste heat recovery system. Such tests were conducted with the intell[ion of incorporating any Signifi- cant results of thi.s testing into the design of the advanced ':apor generator wherever possible. The soot cleaning device selected for test- ing from the several deSigns reviewed consisted of an air pressure actuated. butterfly valve which is installed in the exhaust (outlet) stack of the vapor generator. The operational principle for this soot blow- ing mechanism or "Burp Valve" is fairly simple. When the vehicle decelerates or descends a hill in a "no load" condition at high engine speed, the valve is c!.osed. With the burp valve closed the diesel engine will pressurize the exhaust sys- tem including the vapor generator enclosure. A pressure level of 15 to 18 psig can be attained in this ~nner in a very short time (less than 5 seconds). Having reached this pressure l.evel, the valve is opened and the sudden expansion of the pressurized exhaust gas should dislodge soot particles from the heat exchanger's finned tube surface and carry them out of the vapor generator. The dlesel-QRCS testing proceeded by first quantifying the degree of soot fouling that occurs within the vapor generator during 100 hours of operation. A 100-hour test interval was found in two earlier' endurance tests to ~~ of ::ufficient duration to measure the ef(e~ts of fouling on the heat exchanger. ~o soot blowing was perlormed during this first 100-hour test. Measurements during this first test, later verified by a sub- sequent test. indicated as much as a 25-percent reduction in !teat exchanger efficiency when soot blowing is not performed. When soot blowing was performed a reduction in vapor generator effi- ciency of 20 percent was measured. This 5~all difference does not suggest that the soot blowing mechanism described above is successful in com- pletely preventing heat exchanger fouling. In fact, several aspects of the laboratory diesel·' ORCS engine test are different from an actual ve- hicle installation and on-highway test. For ex- aliiple, the soot blowing was performed "hen the diesel engine was being powered a~d not when it was under no load (i.e •• no fuel injection) and high-speed conditions - as it would be during on- highway application". Ihe labor.ltory setup ~ould not duplicate these on-highway conditions and still expect to adequately pr.essurize the vapor generator enclosure. The pressurization oi the enclosure was. in fact. further limited by retro- fitting the new burp valve onto a previously used heat exchanger; a heat exchanger not originally designed for high-pressure contaiIwent. The vapor generator cylindrical enclosure was sufficiently "eaied against leaks to record a maximum pressure of 12 psig at pe.ak engine loads but typically 6 to 10 psig; during part load operation. Leaks did occur duri.ng the loo-hour test tha.t resulted in maximum pressure levels of only 3 to 5 psig. The Significance of containment pressure in pro- viding enough expansion force was quantified dur- ing one test at the lOO-hour mark. It was found that an inlprovement in the heat transfer coeffi- cient of at least 10 percent and as much as 25 percent could be obtained if the heat exchanger's .::ontainment pressure was maintained at L! psig instead of 8 psig. A similar burp valve will be installed in the advanced vapor g;enerator (VGIlI) which is de- signed for 15 to 18 psig pressure containment service. The improvement in vapor generator per- formance will be mea,sured with soot blowing at these elevated pressure levels. In addition to the soot blowing tests, the laboratory testing bas verified conclusively that a water wash procedure for cleaning t.he vapor generator does work effectively in n~stor~ng the" performance of the vapor generator to an as new condition. Figure 9 displays the results. For this reason, the advanced vapor generator design will include water spray nozzles located at the top of the finned tube core. These nozzles 1011.11 allow for periodic but thorough water washings of the core during routine vehicle maintenance periods. Advanced Vapor Cenerator (VClllt - A new vapor generator is now being fabricated for sub- sequent testing in the system dynamometer facili- ties. The design f,~atures of VGIIl, shown in Figure 10, include: GI Post test design modifications developed through vcrI testing (II Simplification and cost reduction of fabrication f>l lncorporatllon of soot cleaning device Several design modifications have been in" corporated into the new heat exchanger based on the test r"sult,; of VCll. To prevent exhaust. gas bypass and heat loss from both the outside and inside surfaces of the core, insulation has been placed in these areas. A cylinder valve has been added to the diverter mechanism to close off the upper port when the vapor generator is operating in the bypass ::lode. Together with the inside stack insulation. this valve prevents any over- h.~ating uf the \Jorking fluid that might occur when bypassing the system.. (Overheating was ob- served on d few occasions during prior road tests on TBV ~o. 1.) The above feature of \'ClII also aids in the energy "torage capability when oper- ating the organic fluid throttling valve. . This new · .. apor generator design contains ne', featUl'es Lhat afe aimed at reducing both the :natel'ial costs and labor efforts to construct 'this heat exchanger. A major design change is the ..:ore which nO"J consists of 15 sets of spi- rally .... ound (";:>anca"e") f inned tube coils. as sho\m in the drawing of Figure 11. This vapor &ent'rat0r C(lr~ has t.he follvwing featur~s_ @ The tube dnd fin material <1.1''' ":01\- structed of low carbon steel. - Ten ";>an,:ake" coils are 5/8-in.-o.d. tubes \a.~ in previous vapor generators) - Five "pancake" coils are 3/4-in.-o.d. tubes. This set of coils are in the vapuc ph.ase region of the vapor gen- erator ,md the larger tubes viII de- creas", the flow resistance ui the working fluid in this section where most ui the pressure drop occurs. o The center core tube is an integral part oi each ";:>.allcake" coil. - This center core tube is used as the mandrel to wind the tube coils when fabricating the cor~. - Each center tube core has a helix bafflE, (see Figure 11) to guide th~ finned tube when initiating the wind- ing procedure and this metal helix also acts as a gas baffle to prevent exhaust gas bypass of the inside core surface. • The pan(:ake coil design has all tube end connections on the outside diameter of the con~. This feature eliminates the inside connections of the previoub vapor generator and also the two-step brazing operations. Tube connections are straight thr.ough rather than U-bends. reducing the pressure drop on the fluid side of the vapor generator. VCln also \Jill contain soot cleaning mech- anisms. As shown in Figure 10, there is a built- in water spray manifold with an outside connec- tion that will make water washing of the heat ex- changer more efficient. The soot blowing valve will also be mounted at the stack exit, as in VGII, for testing on this vapor generator. In the recent tests on VCII with the soot blowing (burp) valve, the pressure level buildup in the vapor generator upon clusure of the burp vah'e was limited due to inherent leak paths in the heat exchanger (VCII was not originally de- signed to withstand appreciable internal gas pres- sure levels). Since the capability to build up pressure (internal to the vapor generator without appreciable gas leaks) is necessary to properly test the effec~iveness of the burp valve, partic- ular attention was given to adequate sealing of VCIII. This nelol vapor generator is current ly being fabricated and will be tested during the current program. CONTROL SYSTE.~ OEVELOPhl:NT - Developmental work has ~ontinued on the microprocessor-based control system during this prugram phase. Initial efforts consisted of mocification and installa- t ion ufo t he control system (updated Version as it exists in TBV :\0. 2) into the systtJl dynamometer tacilities to serve the function uf general cun- trol of the compound engine for all testing (i.e .• vapor generator tests) and also to serve as the "baseline" unit for further development wOl'k un the .;,..'ntrol ~yst\!m ~fii..:icn..:y JptimizatiQn .. An .lutomati.c data acquisition Systelll has been designed and built for the ..:ontrol system and this capability has been incoq)Qrated into the rBV No. 2 control system. This feature elim- inates the need for manual recording of the Bot- toming Cycle System parameters during uperation. Another major effort this year is tl~ fre- quency response tests. which .He still in progress in tlk systelll dynamometer facility. tv vptimize the tel1!lperatu.re error gain and establish control ;;y5t.:1'1 stability during transient uperatin~ conditions. Data Acqtlisition System - The second Test Sed Vehicle (TBV No.2) is equipped with a microprocessor-based digital control system with added automatic control features including a data acquisition system. When a set of data is de- sired during a run, the operator actuates the data button and all pertinent parameters of the bottoming cycle sj"stem (temperatures, pressures, etc.) are automatically storej in memory of the on-board computer. The system is now also equipped with self-diagnostics which alert the operator to various problems (I.e., low organic fluid flow, high condenser pressure, low lube oil pressure, etc.). The schematic of Figure 12 shows the inter- facing of the various features of the control system and sequence of events from the data tak- ing co~nand to the final data printout. Figure 13 is a photograph of the CRT display, shOWing the page I data (there are two pages of data) being monitored during actual operation of the system. When the data button is actuated, the parameters being displayed on the CRT are stored in the on-boa.rd computer located in the control system unit $\lOWtl in Figure [I.. After a run or series of trips, the data are then transferred from the on-board computer memory to tape and/or to a data ter!ninal for printout as shown in ,'igure 15. Frequency Response Tests - Anuther majur eifort on the control system is to establish the maximum gain on the "set temperature" control loop to optimize response time and prevent in- stability du~ing transient conditions. Some fre- quency response tests have a 1 ready been performed to record the control system response to sinu- :>oidally varying input signals. From this data ",,-)de. "lot:> oi gain and phdse an);le are being developed to show the optimum temperature error correction dnd rate error correction while main- taining <. ,Hvper :>lability margin. In the initial frequency response tests ;:>er- tl")rmed .. )n the ~0ntrol ~ystem. tht:! temperature er(l>r gain. KI n - TSET) c)t tLe cont.rol equation ShU~l in Figure 3. was investigated. Although the .;,)nclusi,1llS from these tests are valid eml)' ior 1 inear :>vstems. the thermal in"rtia of the vapor 5"nerator should mask the 0t 'J.er nonl inear- it ies ~ The steady-state temperature gain was deter- ::lined by changing p'Jmp st roke .1 fixed inc rement .• nJ recL)rding the two ~teady-'state tempet'atur"s dt <1 :>pec if ic ope rat ing 10dd dud speed condit ion un the engine. The te'''perature feedback loop was then opened and J, voltage signal "as imposed on the control sl.llWl',ing junction with a sine wave gener- ator. The $ignal level was then adjusted at ex- tremely low frequencies to provide the same tem- perature s\!l.n& chat was obtained during the steady-state test. Signal frequencies were then inc rea sed \li.th both input and 'temperature output being recor.:lt.>d on a strip chart. The stability criteria for a linear system • A phase margin of no greater than 45° (,iegrees frow. -180 0 \ must exit at the o db attenuation curve. • At the phase shift of -180 0 the gain (attenuation) must be no greater than -10 db. Figure 16 is a Bode plot of the data from this steady-state test and shows the two stability criteria to be met for this condition. As a test, the temperature error gain of the control system was increased by approximately 20 percent; this resulted in an oscillatory system with a turbine temperature limit cycle of ~30·F, thus indicating the gain for the system was optimum at the ini- tial test point. This test was performed at an engine operating condition of 274 horsepower (1800 rpm and 800 ft-lb). Additional dynamic tests at other power levels will be performed during this program phase. WORKING rLUID THROTTLE VALVE - An organic working fluid throttle valve has been installed on TBV So. 2 at the outlet of the vapor generator. This mechanism improves fuel economy by contain- ing heat energy for use in an optimized schedule in the operation of the Bottoming Cycle System. The ORCS control system automatically operates the throttle valve according to the "load" or "no load" conditicn of the diesel engine. The valve remains in an "open" position when the engine is under a loaded condition and "closed" (energy storage mode) when the engine is not loaded (i.e., driving down grade). The throttling valve is positioned in the organic fluid line between the vapor generator exit and the turbine inlet. The signal to close the valve is generated by the control system when the compressor discharge pressure falls be- Iowa set value. A small orifice in a line paral- lel with the valve acts as a bypass circuit to allow a small amount of fluid flow, thereby pre- venting l,)cal hot spots in the vapor generator. Rationille - The Test Bed ,'ehicle (TBV ~o •• ') is theUJ-timate laboratory for testing the throttle \'alve bec.luse of the exposure to reai road transient conditions (grades, etc.) ~nd the abi lity t.o run t.he same route with and without valve operation for compaLison of fuel economy difference. ,During preVious ruad testing on TBV ~o. I at the Mack facility in Allentown, PA, the idea of controlling the energy flow from the vapor generator was formulated. The energy treriod of high demand from the diesel (e.g •• climbing a grade). the feedpuap stroke increases to match the increase in exhallst gas leillperature and f lou rate. As the deqand falls to zero, the vapor generator is still capable of transferring con- siderable energy to the organic working fluid. This energy transfer is reflected as an increase in turbine inlet pressure, which subsequently delivers power to the diesel power train at a time of low or zero demand. In the worst case, the energy created by climbing one grade is com- pletely expended on the succeeding downgrade and the next upgrade is met with no stored energy in the vapor generator. TBY No. 2 Throttle Valve Tests - The second test bed vehicle (TBV No.2) is equipped with the advanc~d power conversion unit (peU) shown in Figure 2, a microprocessor-based control system, and the working fluid throttle valve. Under this task a nominal 750 miles of road testing ~n TBY No. 2 was to be performed to test the effective- ness of the throttle valve. These initial tests were run on TBV No.2 (Figure 17) at the Mack Engineering Development and Test Center (ED&TC) in Allentown, PA. These TBV No. 2 tests are being operated over the same basi.c 278 mile "roller-coaster" fuel economy and endurance road test course that TBV No. I had previously run. Due to several construction projects on the route (over boti' the mountain and highway por- tions), there were a few detours which length- ened the overall course from 278 miles to 280 miles. Also, there were numerous "slow-down" areas ,lad starts and stops oVer the ...:ourse ui ~l fun tchatc did not ,-,xist during prior tests and prevented the THV No. 2 bottomin!~ cycle system from operating as effectively as in previous tests with TBV No. I. PerIvrmance and fuel economy results have ':>een established on TBV No. I in two prior tests performed at ~ack in side-by-side tests with a control vehicle. The second series of tests with TBV No. I (4. 98 m~'g avera,;e fuel economy) showed a 1~.~3-percent fuel savings over the control vehicle (':'.35 mpg average tud economy). These ?res,~nt throttle valve fuel eCl'nomy test.> un IB\, So" :. were performed over the ellurse without tile us~ 0i d ~ontrol Y~hi~l~. ~ack hdS dismantled th~ control vehic!e clnd no others dre dvaildhle that Cdn be used as a comparison ,,'e- hicl~ ior this t~st series. The test results at fuel economy datd vn the control vehicle during the two separate test series with TBV :-00. 1 were LOllsisten' and "howed similar fuel economy. ~ack consid~rs that a valid fuel "conomy :1umbcr to us~ for the ~ontrol vehicle f,,)r th~ ~omparison Jf th~ TBV ~o. 2 test results is 4.J~ mpg. The tests were otherwise run in an ~d~n-' tical manner as .. as done with TBV ~o. 1. The Sdtnt! two [raile.-s were used and alternated durit. each t~st run for the entire series of tests and. at least. two dii ierent dri.vers operated the vehicle . ..\ total ,)i II ~O miles were run on rBV So. 2 with the throttl~ valve 0perating. The overall fuel economy was 5.01 mpg which represents a fuel sav ings ,compared to the cont rol "ehic le fuel economy (4.35 "'pg) of 13.2 percent. This TRV So. .:: f ue 1 savings is to date the largest improvement attained over the ~ack course by a test vehicle 249 equipped with a bottoming cycle system. TBY No. 1 in the last test series showed a IZ.5-percent fuel savings. The results of these road tests on TBY No. Z are summarized in Table 1 and are highlighted below. • Tractor-Trailer Combin- ation Gross Vehicle Weight (GiI\I) • Test Mileage G Minimum Fuel Economy for a Single Run • ~xi.mum Fuel Economy for Single Run • Average Fuel Economy • improved (Fuel Savings Compared to Control Vehicle) These tests exposed TBV No. 2 to 72,000 lb 1120 miles 4.81 mpg 5. I ~ mpg S.Ol mpg 1 ') )"" ........ k formal road use for the first time. Prior t(' these tests, the vehicle "as essentially garaged with only occasional local operation. Although in tnis limited mileage test TBV No. 2 did show an im- provement in performance over TBV So. 1. more road use of TRY No. 2 is necessary to shake out the infant mortality type failures and to "fine tune" th~ vehicle for optimum performance. It is some'lhat difficult from the results <)i these tests to deter.nine exact Iy what amount c)f improvement is Jue to the throttle val"e, but elll ORCS ddta observations during the funs indicated that the throttle valve was operatLn6 as designed. FUTURE PLA.'\S It ~s Thermo Electron's objective to finish the development of the Truck Bottoming Cycle Sys- tem in as complete a fashion as possible, given the constraints on available resources. We want to reduce or eliminate the remaining technical problems of the system and have iully functional operating hard10lare (e.g •• Test Bed Vehicles) that (;an attract venture ..::apital when th~ Mc.lrket !I.."C ~ne rgy Coosc(vat.il..}.ll i:nprov~s .. Our best chance ior dccomplishing our vbjec- tive is to ~ontinu~ wor~ing 0n the two T~st Bed Vehicles ,figure i8) which elre reallv our labofd- tories ,1n :,'h,:,els. -':e 3re drranging with DOE to . maintain control over the use of these vehicles through a cost-iree l~ase afrangement. We plan to support continued testing and development ,)1 the trucks by u::iin~ :.n\.°r3 1n (:\.)mmcr('i~ll :i~r\'L:e ~.'"' defray "peraling expenSeS ·",I.de testing them. TBV ~o. I will be us,-"" ,'ur ~rine ing~ne L\i\'i- sian in Detroit to delh'cr its products ~o East and West COJlst distribut,>~,;. ray No.2 will be loaned to selected e"","""r<:ial .:arri"r5 dnd ",'m- ;>anies. withln the t rue ~ ... !1du$t ry i 0r \."1 pc rat l..'n on revenue routes and ·,·_~:ing for perh1ds ,)i about I 1IIOllt.h each. r: .. 'mo Electron will "rcw~.le tl'aining and equipmen .lpport during these loan periods. The response oi uSOUND RA01ATOR TO RADIATOR FROM __ RADIATOR 15% REDUCTION IN FUEL CONSUMPTION Figure 1. System Outline Fi9ure 2. Advanced Power Conversion Unit Assembly 25\ , • COMPRESSOR DISCHARGE PRESSURE (PCD' CONTROL SYSTEM EQUATION . PCD [ H] ... =I(,~- 1 + K1(T - Ts.t..). k:.,-r Figure 3. Control Schematic for Bottoming Cycle System Figure 4. Dynamic Loop for Auo"inol Working Fluid I 100 ,---....... ---,.-- --r---~r---~~--..,...-- T£!)T O'P'f;R"TING COHDITI-QfrolS T "51""'- po - 5oOI0S100 Fl '" F\.oe kA T£ ! ~ qph Figure S. Fluorinol-85 Acid Level liS Test Tinte in Dynamic Fluid l.oop 1 ! , . • VIRGIN WOItItlMG FWIO PRJOa TO STAaT OF TEST YIXTUR( AMALVSIS Fl.l.IORtMOL-IS 8 ~~===~E IfO:::=:::::Ecr:"" ===::==:=--:-=:=-r-r-l tz- _ATER 1 I - FLUOR_NOt. ~ o .. o ... o .. o • o o __ ~ __ --L-------L ___ L __ N o _ ORKINC F'lUIO 4FTER 1000 HOuR TEST \lIXTllRE ANAL .... SIS FlUORINOL 'J. ~ '" o .. o ... o '" o .. o E---,-----~I .. o SA\lPl£ I"'-JECTtON c.~- ."TER ===========------ FlUORI~Ol ... o Figure 6. Gas Chromatog,oaph of Working Fluid for Dynamic Loop Baseline Test Series o o Figure 7. Vapor Generator (VGU) on Test in System DynanlOilW.'ter Facilities - AU • , Figure 8. Vapor Generator Core 10..----------,- I I - o o NOTE: ALL DATA TAKEN WITHIN FIRST 5 HOURS OF OPERATION FOR EACH TEST TEST NO.1 AFTER WASH _.L __ ._---.J:_,~ 1000 2000 3000 EXHAUST GAS FLOW RATE (LB/HR) Figure 9. Vapor Generator (VGIl) Perfonnance Shown When "New" and After Water Wash Procedure 254 m • ''<, , • ... t'- I 'P • 1 "l~ -- - - T' Figure 10, Advanced Vapor Generator (VGIl!) , I "- ......... " __ e..._~ "-;" ",-" " ~. i -' . - "...,. ..... ~ -"'-. ....... "::~~ .... , , 1 ) (-I \...) '(j '("0 ,0- ' . Figul'e 1 L Spiral "Paneatke" Coil fOI' Advanced Vapor Generator (VGlIl) :7:'~ ... ~..£?L- • 4. 4~ - • }-1:-[-- -:R~~~T~---i ON-BOARD TEST BED I DISPLAY I VEHICLE BOTTOMING I CYCLE CONTROL 1 I SYSTEM EQUIPMENT I I I ! I 1 \1ICROPROCESSOR I CONTROL SYSTEM I BATTERY BACKED RAM FOR DATA STORAGE I I I I I 1 . I -.J '------r------- ! ! ---~:t,~-----~-,~: I~~o~J--l TERMI NAL FOR FOR DATA I I DATA PRINTOUT TR~ I ~---- -------- ----- --~-----~ -\FTER TEST HOOK GP , -~INSTRL.MENTS FOR OA Til RETRIEVAl. Figure 12. Schematic for Data Acquisition System Figure 13. CRT Data Display of T ,-uck Bottoming Cycle System in Operation Figure 1 Il. T BV No. 2 Cont."01 SY~Hell'l \kldule 1-:,: ':1:.: .;,~, 8-SEF-1 -8<:; FtJI'l I":, 1.1\::,,", (If' = 1-;'.-:' F"TU ,,54. TI1I'I il.;- FSl !tloE. F'~I F(O OC(, T(.O 1'1u. f.H1 c.{J.~ F'SI H:4. loE.f.. c,*,. Ie..:. F'lI = 650.F'Sl Pl.O 94.2 FSl T50 .. 141.11£.(, HI :: 517. OCG STR :: 81.2~~ Ttl(> o. 5C:4. lEe. TGI *'9. DEG lGO TLO 1~. r£G 8-SU"1-~:<:' 1 '5: 10: c? rut t() IX":: (If> 18. 5 F~, I toIlE. = 18';'-0 "l-'~I F'Tl ~12. F'Sl TTl 470. 1£(' F TIJ 618 F-: I F~(; - 1~.~ F'SI r'U) %.c: PSI SlR 78.'0·; TI1I'I <;:..(. 10((, T((, = 164. llE.G 1~;C: 140 11£.(, TIX; ~. l£G TGI ~. 1l(G 1(.(" .- Xt:-. loLG lU.' 135 DEG 8-~:-E.Pl-8C. 14:4,: l() HJtt t-o (101 CloP 1-;'.(' hI tlH:' 1. ~_1. f.HI HI ~,98. F"s1 TIl 46-5. OCG PTI.) t;.(1t •• FSI F~I) c.i..1.5 f"~·l FLO ~.'" F'SI STR 82.5;; 1"RI'l TGJ. :--1 .. -: 1.£1, TLU Ib~'. I£G -ISO 140. OCG TUG 470. ~c. .. 1000e, Tl,(' c.~~. ['(l, TU) 131. 1I(G DATA PRINTOUT KEV COP EngIne Compressor Discharge Pressure (psig) PTU ~ Organic Working Fluid Pressure at Throttle Valve Inlel (psla) TAM::: A.mblent Temperature (OF) TGI :: Exhaust Gas Temperature at Inlet of Vapor Generator (OF) :-lDE = Diesel Engllle Speed (rpm) PCO = Organic Working Fluid Pressure In Condenser (psia) TeO == Organic Working Fluid Tt.!mperatUT(! in Condenser lOf) TGO = Exhaust Ga.s Temperature at Outlet of Vapor Generator {OF) PTI = OrganJ.c Working F!uid Pressure at Turbine Inlet (psia) PLO ;; Turbine Lubt.o Oil Pressurt.' (psig) rso ~ Turbine ~eal Oil Temp~r.dure (vF) [LO = [urbJ.not! Lube 011 Tt.~rflpt..'rature (:'F) rTI = OrganiC Worklng Fluid femperature at Turbu\e lnlet l ";-F) STR = Orgamc Working F1wd Pump Stroke (t) rVG = Organic Working Fluid Temperature at Throttle Valve Inlet (OF) OC(, Figure 15. Printout of Data Sets Taken During Opoeration of Trucl< Bottoming Cycle System ,...,-------- --------.Ir ------, OPEN LOOP FREQUENCY RE!;PONse FOR ! ENGINE OPERATING CONDITIONS: ....; 20 SPEED = 1800 'P'" TORQUE = 800 ft-Ib ~ I 15~ ~'" 10- ~ .. 5- 0- -10 - L---___________________ ...l .. ___ .______ . __ . ________ ------1 0.0001 0.001 0.01 rnEQJ!J£/I!CI' I RAO/-.l Figure 16. BodCi! Plot for Bottoming Cycle Contml System 257 ---------------- Figure 17. Test Bed Vehicle (TBV No.2) Throttle Valve Fuel Economy Road Test TABLE 1 SUMMARY OF TBV NO.2 THROTTLE VALVE FUEL ECONOMY TESTS AT MACK TRUCKS, INC. (FALL 1982) : :"' 'l ....,. - .' !". ::.. ., ~ ~ .... .:- .;. ..::. .",' .. - .( -" 6 . ":".'" Figure 18. Test Bed Vehicles (TBV No. 1 and TBV No.2) ---------~ - • QUESTIO~ AND ANSWER PERIOD Q: Is there ei ther competi ti on or compatibil ity between this approach (bottoming cycle) and the previous talk in tenns of turbo-compoundi ng? 1)0 you see these as bei IIg competitive or do you see thelil as beln!1 complementary in some cases? A: I' d say they are both competi ti ve and coraplementary. There is certainly the potential to do both waste heat recovery and turbo-compounding on the same engine if there is enough energy in the exhaust gas. The two ener!JY recovery systems would be in series, fi rst turbo-corapoundi ng and behi nd it a Rankine cycle unit. In the near term - as far as cOOIllercialization is concerned - we aight find that they are competing systeas. It takes a little imagination to envision selling both packages with the conventional diesel engine. But with the adiabatic diesel engine, in fact, I think some of the studies the Anny did showed projecti OVIS wi th the two (energy recovery) systems in series. With the adiabatic engine, there is a lot of heat in the exhaust gas so it is probably quite reasonable (to use both systems). Because we don't recover the blowdown energy in the exhaust gas, just the sensible heat, the sum of the energy recovered by the two systems in series would be greater than either one alone. -- - Light Duty Vehicle Diesel Engine Assessment Program Passen~~er Car Diesel Engine of the Future .~ . This .. ~.ull??r. :'J.t,l.ln~;'b- i::c ~bJect.lvcs -.Jt t.he Light ~uty ·.·~~l~:0 ~lescl ~~qlne A~sessment prog'ram dnd ~:1e .... \)[."" ~asks requIred ':.0 ac.',:om- plish :hc' ;,:une .. -:':: ... ' ;\()wer rlant---~l.·i1lr--veh;cl~ requl.remt..:'~,:s -=)r' -:~>_~ :·....It'....:.re ~lut.0mobllc ..lr·," poten~l").! l'~' : ~·-"r;l:l~:".(] ·':L(:jl:· ... _~ .:':Hl~ept~ _lnJ. adVdf'.....:l~·j ~t.._.:::. ~_;,c::...~-; J.V~ill~lble ~u :7Iet:.'t. ::".o.,;~ rcriUlr~~me:lt:; 1r· tje~~t.lfl~~d ..:1!!j ilSC'.lssed~ ConceF::·.l~lL " .. ·.L.~:~l·_ ""-':. ::d~ _::l<·:L)s~~J. d :n<:.xi- ~rat:e ~; t-O_':, : :"-..41' ··_!"I)!'Z'_. :.l.yh 3~1Er jlL'.":;t~l enq l:).L' ., .. :: ~ _-,; -11 ::):'l_L"_';h':;~ .it' _' ,J. ";~.'. !..;.c ~ J.!: . .l , ' __ ' ." ~ .>.... r:-... · • !.··_·f!I .. l.:.~· ':':. ::-:e r'·.l: ... ::l!l'-1_ .... ~:..i~ .1:'':' ."n"_· ,'~' ::~e :!·~:n..j ~!1anq~~.s ':::d.~ .. kl l..1Odt l_~- ':. _lr:X.h : _~r.;,,-'\...;.:.J. t.!!l>..l l:lt. ... t ~ ~v ... • TAI .. >,'--- .... !, ..... ~ .. L:n.'l\l::~ :':11::!.~~~1 ::.: _ .. _ :",-,':1 ·_·:l~l::c, :':1(> ~ _'c.:- ::.:'-.... ~~. ~ .. l..:s. :".U" . ."i.l.::t: :.:;,-'::.~lUl:1."'; ,-::-.-l~, .is ·Noell. ..l~ ...l ::vst _~: _'-:':-:t.'1' 'i'_·V·~·I.'-'Fme;.~ .jctlV!.:!.':.~S underw...l'l :.:: :::'t.' ::t..'..l'.": !;"~:'.: .:.:.~st.:'l ':.C.l...:s. t?ll'-ll':lt.' .:'c .... ~: ... ~:: ~ .. J,..1i.i '.''L"''!-~: "'t:'~': pdve :::e .. ay fOl- !.:l~~ :":'~:l~ . '..l:.: :~.'~:l_·lt.~ l.:.escl ~"'n.Jl:1e of ~h~ :' ·.J.t'..1!·~. 2\)1 Roy Kamo, Luigi Tozzi, and Raj Sltkar Cummins Engine Co. Columbus, IN d.evelopmcnts Fossibie are ddvancem~..!nts ln :naterlclls. turbom.achines, heat transfer technoloq'!, dnd des1qn ~echnLlues 0 The pU.r:.-pose of tnl.S :...nv Dlesel l\ssessmcnt program, ~~nded by ~ASA/JOE, is to ldentl:'-/ '.:he :<>t· ... ntldl ... :, promLil:.q concepts dnd a.p- ;JroaCiles · .... hiC':1 ',,111 ..idvance :.he :.u'J liesel : :.-0,J....:: .. L·-.; .... 1.:..1 !.)e i'~"':'::'':lf':'t.:d · ... ·!1er .. : !'_<.J.:::i..:il.blt. • .lnd dnaiYS1S cf it:.:; in:l'.!ence on t:!1ql:H~ a::..! .:it..i.Dscquently on veh1cle performance "II1II111 ::>c jete['m~ned, The p['ogrdlll w111 also ljeatl fOf the technoil)g leal ... lreas where ;-.!:'; · .. ork 1 :.j r'(-'{~!uir-~d to br i:v·l 'these ..::oncepts .1.'·;,i 3.p- i'rodch~s to fr .... ll~lon. :-~1t:.) :)d.::;eil::e ·;'.!:1l~·.iL' l:~ ~n:L ... ·:~ J:. 3dv~lrh;"':,: -ile:::;el ·~W'-l!.:le #1'111 ~e l:1=-;t..llled :.:;: .\ ,,' rr~ln~ml';:;SJ,On _ :- 3 ! r: . ;s :-~lt" ·;ehl.:le lnd jrlve ':,r.llr!. :jpcClrl.,",·~t:',):l ..1;:J .Ana;.Y:-;ls .:11l. !...'t,..' ~'r'.Jvl"i.;~(} ::y :::e :-'ord .~ct..)r : .... 'Illpan.y ... )t ::~}drb0r:1.. '-!lcnl~1azl, 'N'!ll-.:'!l :'.:> .1 ~~contractor to this program. RANKING OF ENGINE CHARACTERISTICS Although each engine application places d1fferent we1ghting on each engine character- istic, the LDV diesel engine requirements were decided jointly with NASA. The engine require- ments and their ranking in the order of im- portance were as follows: 1. fuel economy on Federal =mbined dr1ving cycle shown in o'igure 1 2. Sroissions 3. Cost 4_ Jrlv€ablilty 5. Slze and ..,eight "cliabJ.1ity and durabil1t:: 3. :-\ulti:·.lel 10 ,......----~---'--~-------.. - 10 ~--------.--------------____________ __ 4 :'6 i i ,,\-----, ------------ '----j 1..-. . ------------,.-; --I , , 1 --_____ F~ __ .....J ! . , ---I 1----------, 1---1 ---I;. _I . ~ ,...-J. . ,-oj ~ , o. ____ ~ :1--: g\ :-:1 ~~ :;.~ ~t :1 :: l __ , • _____ ~ __ . t ~: -~ :1 :: _. _I -! ...q -~- -'1 _'~, . -! . -~..,-~~,~.--.----~"'" .. -.. aoo :.~, .. _. ~l_;.~:::_1.:JU'":!...")~__. _If :::12 c:.";:':'.t2' ;..)<..) ..... ·er 3.6 3. :··.J:1.~t:0:1 ~! :.h,e per.::entage _)~ :'';c':' ::'.lr:~e.j _"ver :.h.e fe3.e·r al· ,drlVl!1y c'/cie Based ''In past anJ. ':'"lrrent ..:i.!.csel ~ngl:,.e :e'';:1:101~y, 'lla.ny .JF:'lO!lS are 3Va.:. :'.lble for _-:-O::'Sl.j~ratlon_ ~~otabl.e- ..lll\onq '.:":..... • ~:\ .. '!'. ....ire: 2:1Qll".e :':'cles :u~d ~-oClfFl"'!,3."lO:1" :·t"cc:"!a.m.o~r \·5 .. "!.lre...;~ :.::~..: :-::,.:-;C, .;dlaba:.::...: :··..ll·boccJ:U!-){)und l~"!q ~lll~r =yclc At~1~50r~ ~~'=:~; .5;. ... (.'\rk 3.5S1st :'urboCI!,u-gers : c:>:npr ex ,'051 tl ve j~spiacernent .... ~~ra.ml.:-s Injection system Variable displacement Antifriction bearings Gas lubricated pistC'.,/liner Oil-less operation Preheat cycle 'Jariable inlet and exhaust valve timing Higher air utilization ENGINE CYCl.ES & o:JNFIGURATIONS The conventional four-stroke cycle engine 'fllas compa.red to ~he t.t«>-stroke design _ In the fut'.lre. the adiabatic concept is expected to emerge as Cl reliable low ma~ntena"lce power plant wit~ no cooling system. further, the utilization of waste :'eat from t:-te exhaust c3n further l:1creaSe the ",ngine efficiency. The loop scavenged t-..'O s!:roke or the opposed piston uniflow jes1gn has much ~o offer since poppet val ves are Clot required. The opposed piston two-stroke design has ~~e n~st ~o ~ffer because it does not have the complexity of the cylL~der head. Heat loss 1S minimal =or this jesign. When the minimum friction gas bearing for the piston and cylinder Liner is =nsidered. ~'e opposed piston design ·~l':~ ;10 sl.cie thrust. o;-~ the engine is ideal. ~l~ure 2 shows ~te cross-section of a sW1ng beam two-st.roke opposed piston engine under jevelopme..~'t. by Sir W .. ; .. Armstrong w111t·oIiort.h 3.nd 2ompa.'1Y. -----, .. ------------.......... --------.-.. ~------.. --------..... --..... ----... ------------------------------------- The use of advanced ceramic materlals is expected to overcome the maJor problem facing the two-stroke design. i.e. thermal loading. Absence of lubricating 011 paSS1:1g through t:he ports will enhance ltS eII11SS10ns character- lstics. Indeed. L~e advanced technology. i.e. adi.3.batic concept, mi;tlmurn friction, etc., certal:11'/ favors t::e opposed ,liston two-stroke design. :'he other features -'-'hie:: favor the two-stroke engi:1e design are: High ~ipeciflc outFut :....ower torque fl :Jctua t~()n ~o val. ves ::>r gear t iml ng ';ariable cornpressio:1 rat>o (oF posed piston deslgn) o:driable air flow t:'r~ug!1 iX>rts The fouJ::--stro1te englne : .. 15 :;erved ..lS · .... ell over the '/eclX's. Ho· .... ever, to ::ake .J.dva:;.t.age of the new t?rnerq ii:'-1 eng ine +: e(.:l!lO logy , additional complications :nay ::..e :leccssar':, t.o ...:omt=-~te '",ith the two-stroke jeslqn. .:.. ,~a.se ln point will 01'; the cornplexi-:.y 1:1 the :::yll:.der ~ead je:sl.gn wi th 2eramics or 1 t.3 equlvaler.t _ ,~.rlot:.~!:r will be the gas beari::g piston a.r!.j 11.:1t2r, r\ cross- ~lead ~i5ton ·je5ior. :,see :'l~:.lre 3) through a.dditional .:t',J,!:i<., ..3.:otch i'ok.e, ';""10mblC irl.Ve, !::'reSS'J.:r 1 Z"'d :las, ~ ~ 3.:-,'_: ',y~:-:er ~l~~-;rodc:-_ .,,; ill ':=;1::1;"1': ~i,-iJ. :..::' :~::> ':"-::'~;:~X:":':', :;o:--.t.?'t::!~·_,,-::;~;, a four-stroke engine can be made to operate sat- isfactorily in the adiabatic form as in the TACOM/Cummins design shown in Figure 4. AEROOYnAMIC VAlVE f:X .. IAUST ,VALVE Sf AT INSEnT HOT PLATE HOT PLAn lOW£R SfAL CYlINOI:R LINeR AlR GAP 'INJECTOR "'./l'CTOR -lNSVLA TING SEAL INTAKE VAlVE SEAT INSERT HEAO INSULATING SHIU O£CK sPACER BlOCK INSULATING ,SH'" c:oMf'OSt : t; PlSTON BLOCK ?ig, 4 - :.:ross section of :~e TACJ~-1/~'J{M\H1S l!1sulat.ed diesel engi::", :t appears 3': :.h:.s .3tac~ :';;'at the ~mergi!1g .ldvanced enqi!1e o:ec::'''lology ''''111 be more Clseful :0 ~,he two-strOKt.'! engl,:-;'c :':'an ::le fou.r-stro~e ,:·'::,:;l-itl. It ;"las ':ery favorable ::nfJact on Jvet:- -: ':nU1q :~e ;)dsic r:r801t.:ms .): t.::t2 ~wo-.st.roke ·_~:~;.11.!le of t.hc- past: ~:n1.$SlOnS The waterlt!ss .l.diabatlc cnql.ne :;'as recel.ved .;onslderable 3.ttentl0n 1n recent years and for .\ "cod reason. The .;nqille operates · .... lthout water :)c a..lr ':0011:1.<; and iOl:7.tpll:'le$ ~~e iesl..:ra lnd lnstallatlon ::>f L'1e "ngl:-:e l!1t.O .l "leh1cl" . . 'I.osence of a =llnq ,;ystem lJ1\prOVes t.he ')ver- 31.1 t..'ler:n"l effiCiency .>nd reduces t.he ~'"()st. s,lze. -.rcl.ght. and most. l"U.por!.a.nt.ly, unproVes t:.e rel1iiblhty a..nd jurablll~:1 of t.he "nqi:1e. Considerable progress has been made by TA~(/cummins on the adiabatic engine for the 400 to 700 HP size range. Adequate use of ceramic materi.als is made to overcome sOlIle of the technologi.cal difficulties. At this point, the high temp;!rature lubrication problem in the adiabatic engine is the most severe one. Thus, the main problem in the efforts toward minimUlll friction engine with gas lubricated piston and cylinder liner becomes obvious. Lower ca:rbon monoxide and hydrocartx:>ns as well as particulates can De expected In the high temperature combustlon of an adiabat1c engine. However, the favorable NOx emission characteristic of the adiabatic engine · ... as unexpected. Figure 5 shows the trade-off bet'leen BSNOx and BSFC for an adiabatic and a standard cooled engine. figure 6 shows the expected drop in particulates as compared , ... i til a standa~'d water-cooled eng ~ne. 121 11~ i I • 10 .i -CD E !. 9 Cool'l!ld VS .. Ut1QJ!o~Q~d E~~\ilfil~ ~9~Nl@K Clt'4ll~ Vfi. IIM~IIlC Cll'CI@l 1iI1@. 2 DI ••• I fill!iltllil!Uft@ FWl'ID '19, :. - CClinpar isoll between cooled and '..In;;ooled enqines on " BSNOx-BS~'C trade-off bas1s .05 02 .adiabatic va Conventional EMine Relative Carbon Particulate Livels 4& Cooled 16 Uncooled OL-----~~----SO~'~--~120~----~~~--~2~~~----~240 BMEP(psi) ,11' ., - '::=r-arlson betw(>en cooled .lIld ..illco("12r:t. .:ieve10pmect. 15 the use ,:Jf :!Il.cropockets Ln !)earllig :nater~aI5 ~llled .nth s01Ld lubrI- cants sucn as CaF: and ~oS2' as shown in :'igurc 3e , I -----.-~ ~lg. ~ - :r055 5ect~on Jf 3n 3~tlfrl~tion :::t'ar 1:'.-1 '",'::" :':"l. ::'ll,:("of~oQckets :,~ ::le ;ast.. :.. -:.. ' '''as .:onsldered ~~'la:. d. ;.rt.!cl1aJnboe-r e!"l.~l.:le was :-.~cessar·:· !or :-:'1-]:1 speed operat~Qn. 51nce direct inJect10n offers :':.; to lS~ lmprovement 1.:1 fuel ~conomy ":>ver t....-:e ! rechamber # .:l .:-onslderable amolU:~ ~f jevelop- :::~:1t ~~f!.:.Jrts _::- jlr-::-c~ej t~ward ::-l. :".lr~:'.er ,"ore, :llqh BMEP :operatl.:>n w~th slo· ... er englne 5peed to reduce fri~tion. such ,),5 the ':::U1\1JQins :'Qrrnula :.:oncept, is bourAi to enter ~:-.e :.:JV ~lesel ~nt.,lne fleld~ A modern jl.rect ~!1Jectlonf tugh BMEP, small diesel enql.ne 15 sC:Jedulea tc be in production next ·,ear. ·:~llS enql!1e achIeves a :nl.nUlium fuel ~r:swnpt Lon cof ~ .• 3313 ~r'/bhp-hr an.::l. th<1! speCl.f1c ",eIght ::,f ~he ;oack.- a,,]€ LS on11' .1. 5 lb/hp. The Sl.X :-:: ll!lder ·;erslC."\ wel.qhs .1..) lb/hp. In or·der to aCI.ieve mill tifuel capability, a spark assist will be quite helpful. The adia- batic engine has demonstrated its capability to burn Jow cetane f""l down to CNIO, as shown 10 Figure 7. A spark assist can further improve this as demonstrated on a DOE Coal t:tilization Branch prc~ram. Figure 10 shows improvement in combust:ion diagram with spark assist when burning middle distillate SRC-2 coal-derived fuel oil "ith CHB. x .. l 1,y .... · _':::>st.. !lLJ .... ever, for Lhe ~\' ·_-::'::';l:-'~~. :::e :'.u-bo..:.:har:;crs 3.re ~xcep~:10nallr :~:"''-1:-;' ~;.~eed ,1.' - _ " - ..-:),:), -_'1(\0 rpn) :-naC!11=-:cs 't. .adoptable t:o ":.:..lr:.........:;::8n~'X.):..M:.jl:'l'-1 .l~ .:h~ve .i.-:); t'.J .:..y ':'~l:lS on tht! .:) l':"A'er --:~""'et2d ":--':3.V': jut.~ .. ':..: _...:-j( ~_·r:.g~ac as .::iho\ol!: 1:: :" :..;'...:.rt'" -------~ ~- 267 . C'ltt' '1 ... ;. .,--- , , ---_._---, , ~ld l...lb~l.: i ~ ~ .< ~ -: ,.,~::,: _' i~:;..:.;·:· : r "' 11, • "" If_" HI) 1fe • "'II >- u ; .. ..:J~:1er aX.r ~lancillr.q s'lst.em ::onsldered. '.as o::-:e _- Jm;:rex. ~:-he .:cmprex matches ":.r:e r-o::'lu1re - ::te::t. )f ~~e LD',,' !ut.'./ ....:·lC:~ -iU1tc 'ilie~l. 7:!e res~f!.s":! ...::-:'arac:er- 1.':.t..l'::.:S ..ire ..:onduc l'~'~:! :..:: ~..:xcel.i·::t. j,r:.\'edblll:'~; .. -\ .::ornbl:1t..:d ~:::-=lt:::C':' ·:s. :..·.)dd for ..l ·.)rnprex .It'/i a ":urooc::arqer :.s :;::O',r.'l 1.:'. ~·~g'..lr'~ ::":. ·:':-.e :.'~rfor:nance .Jf ~'=,m!-'rex In 3. ':"'::;'" i1e;;cl -;:nG!.:'.e 1.5 --!~l"'e ::::,Vl.J'.J.S _·:':-1!~r·_·x :....; .... :x;:a'..;..:5: , .. ...: l.:' . .lr:.1.:~":.':' : .. ) .... t::l.:'t.· /'Oo·3.::i:t.- rc/ .. .J :'::':'3.1:' ... .:3~~·....:.1 .(.:r:":, ....---....-... Gornp.f8X _--_ rurboChargl!lr ffi 50 i3 i3 u:: u. uJ a uJ z iii :t g 40 PERCENT LOAD .:-:.: ~ •. :{ 1 ":~l:: " .... ':',' ",,:. '. ::':>.' S !. .~'. . ~ t.: ..... :.:--!" 1: :::':. :,,~':··.·~l! _."' • '.::':.'': :.:" ..::'..-:.·..:.ii .1;:;St:~~:.· . ~ - : . ":.: ..... - -. :,::..ll":.J.:ej :..')'.'. :~"'!.~ -:'.lsr:'l:?.J :l:".e . .. , ::C:.::'·~ :.":' ,_,X;~'t~,-,:-:e,i. ,:::r.::".l...4~: - .:3":r'..lct:'lt".3.i.. !I:?-S14:1 • . ~.::1..'"'1' " - ;:·Fdrl<. ,15S:S~~ ':'Jm.o:";'3tlon .'_"- < :; 100 3 90 ... w > W ... 80 :; VI '" .. :;: (l-· __ "",_~_,"\",,_7_+-__ _ ! L o 10 2:1 30 ENGINE SPl .... ::: ~: .!. ..:::: ~ ::' :.. _ .i:.', .:. _ =- . ..,: ...1_,) t:':'1 _. , 1 _ :. ~ :. ... .: :'':.1.: :. _~. :. •• ~ :... l.':' r :' '_t..' .. ~t'~d.t..cr_ ::--.:._~ -:.l:'':':-,~j, ~:-.~ ='_:..q~:'!".!='-'t:~:::_') :''''';'.!'OOCOClFQ'...::1...:! ,'~·":c:n. ·-~ .. l:\.:r :'.1":'~ : ........ :. :,-.. ';:.1..:: ~ ..... ..., ... ·_~mpt,;>rj~ ..... !··.~ :...It..:,J .... ~ ..:lr~ ·_~s~: ... ~.:...1: • -application. The electronl::all:1 controll.?d fuel injec- tion dnd t.::e electronlc intake and t:xhaust valve control 3.dd :.1;; !:o .l :nlcrOprQces~or controlled system · ..... h len '.::an :: 1 '/e opt Lm12ed f':'~'::' '.:conomy, performance, and eml~c.:;....:..-: :;.u.racteristlcs at the ent..lrl::' O;::'Erat 1:1<; r:1~lqe cf :: .... t.: ·"2~licle. :'l:~ally, a me~:1od _.J l.m;::rove tae t--dLt load ef:lcle:12'/ .)f t.:-:.e :-.lr::~o:':)m~,;.::a. '-~:1qine 'Nould be ~lq~l~' ieslcaDie. ~rle :':cle 8el~q lnvestigated :1.0W 1:-; <:.:-:.e : r"~~"::-"1: ..,::· ... cle '.Nh.~r·..: ~;'.e :,,:or.1pre . .;sed 3.1r ::..;:; :~t:?a.:t~d ;,' :':.e ·",'dS:--': '-"X:~dv~t '-.::flcrq'/. :lguL":? i: : ... lus:.ra:es ::~e ,:-':'C'!-= -1:: the ::-3 rilaqram. :':;'c ·..:::::r~=':';'5'"::O:: ':.~m;.."t::-r..l:'..J:~ :nay ~f.: ~e;Jt "'::"':-::5tJ.r:.t J"Jt""'!" }. ',/Lie ·.)r:-er.3.tl.:~'l ::a.nge l.~lJ ~nu.s :!- ~.:: i 1:1....-; ": ::.~ .. ..:.r::;.>.~· .JM.; c ..:.:: -: "':':1:' ': .". l ~:~ 700 L·; :- .. -< 269 .. ----~ T \ \ '\, -,~~.-- -,' ~~ / ... r::-r;:\,,)lotor: :Jmpany has :"::,"-~e: • ...,'..l.bcon- tracttd +':0 20nduct t~e -:!:?:11Cic 3yst.~Tl .. \ndl::sl::'i~ ~ord wlll be provlJed Wl~~ :~e ::e~ ::'.' J~esel Enq!.ne ~JerfUnndnce and eml!:iS10nS ....:nar.:.lcterlstL.:::;. rorj -.':11 d.id 1..11 2onductl:1art on a $!HP basis. AS ilO~~DE ACTIVITY in tt:e area of Adiabatic 2r,gine tecr~ology ac~elerates, it becomes :n- creasingly apoarent that t!1e :hesel engine :5 undergoing a dramatic tecimological transforma- tion. Future Adiabatic .:)]gin!! characteristics will include improved efficien~y, wider :uel tolerance, reduced size and veight. improved reliability, reduced noise, reduced cost, and greater vehicle/engine design freedom. The Propulsion Systems !)ivision of the US Army Tank-Automotive Com.'\'!and (TA~) ·,nd the ~m mins Engine Company :ontinue to aggressively pursue an inn.ovative high-payoff concept called the Adiabatic Engine. This work effort began in 1975 as a ':laper study and has pro- gressed through full scal~ engine feasibility evaluation and preliminary vehicle demonstra- tion. As a result of the pioneering efforts in the area of a:Uabatic engine technol.ogy per- formed by the US Army Tank-Automotive :::ommand and the C\ul'llllins .:)]gine Company, marlY 'jI()rldwide Government, i:1dUstry and acadell'ric sources have beguIl- work in. this general area. This p.ap~r discusses the overall strategy lmd definition, progress, fnture plans, and illlph~mentation 0: the TAcct4/Cuwmins Adiabatic E:i:l€jIle Program. DESCRIPTION AND ADVANTAGES OF mE ADIABATIG ENGI\IIE In the stud,)/' of the~m1cs, the adiaba- tic pTOcess is defined as a no-heat loss crocess, heru:e, the adiabatic q1.ne MAte iMplies a no- heat-loss engine. It should be noted that this engine is not adiabatic, or without heat loss, in the true the~c sense; however the en- gine is without conwntlonal. forced :ooling and stri'v'es to mn,imze heat loss. The .\d1abatic ~1ne insulates the diesel combustion ch8!!')ber with high temperature lIIaterials to allow "hot" operation with minilllized heat transfer. The "hot" or insulated hi8h tetnperature components, include pistOI.1, cylinder head valves, cylinder liner, exhaust. valves, and exhaust pvrts. Addi- tional power and improved efficiency derived from an Adiabatic Engine are possible because thermal energy, normally lost to the cooling wa- ter and exhaust gas, is converted to useful co- w'!r through the use of turbomachinery and ::igh temperature materials. A simplified 3chematic of the Adiabatic £n- gine is shown in Figure 1. Follo«ing the engine flow path, a~r enters the turbocharger (is com- nressed) and then e"ters t:le im;ulated, high- temperature combustion chamber of the piston unit. Insulated combustion chamber components include tr.ose previously noted. ~bustion occurs and useful energy is extracted from the oiston unit. :te ~igh-temperature, high pres- sure exhaust gas is then expanded ttrougr. two turbine wheels to extract as much as DOssible of tte remaining energy. Cne wheel is used to :irive the compressor, and the second is connec- ted by gears (turbocompounding system) to the el'.gine crankshaft to further increase t!:e useful DO\~er out.put of the engine. F'undamentally, the Adiabatic :ngine is more '.:'::icient than a :onver.tional diesel because it :on',t'rts tr:e :'ut'l :-,eat '.:'nergy into adclitior.al, use!ul output. :tree oie-shaped energy balances of various configurations are shown in Figure 2. :he first shows a conventional, turbocharged diesel engine with one third of the fuel energy being absorbed by the coolant, one-third going to the exhaust. and one-third going to use:\u onergy (or power). :he center chart represents an engine that utilizes turbocompounding. ~ere the fraction of '.:'xhaust energy decreases, vnile 'J.seful energy proPQrtionately increases. T:1e last chart reDreSi.. ilts an el'.gine that uses :nStr' lated, tigh-temperature ::omponents, combined , .. itt turbocorr.POunding, to further increase t!:e '.lseable energy .... tile orol)Ortionately :!ecreasir.g ·,iaste energy. Thus, ~!:e ;x>tential for in;:reaS'- ~r.g tte useful ' .. ork of the sam€' fuel is greater :or adiabatic, turbocoruvour.ded engines. (bviatt&- 1::.-, the availabilHy of such an engine would have great wsitiv~ impact on futurE' vehicle designs, narticular~v ul)On the design of military tacti- 7al and combat vehicles. 3y greatly reducing :ost energy and t'ssen- ~~ally eliminating U;e need for a conventional ::ooling system, the '\diabatic Sngine dral'ltatical- l..' :.roproves £\lel econ-.'">ll'\.V and provides appl'Oxi-b '!lat.ely a 40 percent. reduction in weight and vo- lume for the same horsepower fuel. Further, :-rorn a militcll"Y system standpoint, the component 'lol1l1'lle of the· total "under arIl:lOr" propu!sion( 1-18 j syst.em could be reduced by 40 percent overall. ::limination e,f the engine cooling system. in- cluding cooltng fans, radiatol"S, hoses and shrouds would produce a remarkable increase in reliability clOd !I1aintainability. !be engine -,.,ou:ld not be sensitive to most conventional ::001- ing systems damage andextre~l envirom.>ental 214 conditions. Fuel economy improvements trans- late into inCreased vehicle range and reduced logistics concerns. Specific weight reduc- tions allmf improved vehicle response, while less vehicle volume allows reduced armor cover requirements, reduced vehicle weight, arld new innovative designs with improved survivability characteristics. The Adiabatic Engine's ~igh temperature operation also gives smoother -:ombustion and a -.dder range of acceptable [uels. With this engine, the entire philoso- D~Y of c~nbat vehicle design becomes far less restri~tive. ~ncerns regarding satisfactory locations for cooling grilles, air passages, and associated equipment are eliminated. The :ost of the eng'..ne is expected to be equal to or less than its cooled counterpart since engine radiators t cooling fans, water pump, seals, hoses, and costly water jackets would be elimi- nated. Application of the Adiabatic Engine to commercial activities provides advantages simi- lar to those discussed above and in addition in- cludes ~~vements in the areas of emissions, simplicity. vehicle aerodynamics, operating cost, and maintenance. It should be noted that ~ of the COl11l'llel'cial and military engine field fail- ures are cooling system related. 0SJECTIVFS AND STRATffiY The program seeks to develop adiabatic en- gine technology and demonstrate prinCiples and payoff's from feasibility through vehicle inrple- mentation. fte Adiabatic Engine has a~licabi lity over a wide range of power levels and vehi- cle types. Feasibility demonstration performed to date has been concentrated within the 250-500 ~ range. Figure 4 shows potential applications within the military area. Startin« wit,h a (:om- mercial 250 HP engine which is in the lI1i1itary 5 ton truck, an uncooled version of this engine incorporating some ceramics m~ turbocharged :ould be applied to 5 ton and 10 ton trucks. By adding the turbocOl!!pO\md unit and more cerallrics, it is technically !'easible to bu.i1d a 500-700 HP et'.gine. based on a highly IOOd:i.fioo c'JU'4l!ercial engine block. This version of Adiabatic: F.ngine is currently being developed in the 500-700 HP range for application to tracked combat vehi- cles. In the 1!I8.in battle tank category (1500 HP). the Adiabatic &!gine 1oIOU.ld begin ldth an 3.l1 rle'tl design and discard the convelltional :ast iron (o'ng:i.m block in order to cO!llpete 10lith the pmser de.nsity of ga3 turbine and rotary el\giners. Adiabatic: Engine studies are cur~nt1y underway in the 1500 HP rar..ge for possible futur.e main battle t~mk application. f. gl-eat deal of feasibility detilOnStration has ~ aeeolt1pllshed within the progrllllll to date util.iaing both siJ!,gle-<:Jl'l.iDder and IIlllti- cylinder ensine test.i.ng phases. ~iM testing has repelltedly .. &.. , ~J':~Jt!nu~k'!~ ,r r-''rt ! I -CIi ''{ -,~-~)(iXXY"~' '~, '" (loo~ M2 Ml09/U'''W5 ,~ ~: . . . , .f . , ' <, . . FUTURE MilT Pigure 4 - Adiabatic development strategy GVW (TON) 15 15·30 25·35 40 + world rith lTlll.ti-cylinder engine performance levels of 0.285 LB/SiP-H.'i (48 percent theI'1llal. efficiency) at. 450 fP representative. Over 500 hours of multi.--cylinder operation have been suc- cessfully accomplished to date. Installation of an early versi.on of an uncooled engine with?n a military 5 ton truck has been comoleted with initial vehicle eValuation :::onrplete. This vehi- cle installation represents an early spin-off demonstration of the type of adiabatic engine technology which has been oioneered at TA~. ::lesign and initial fabrication of lor.g lead time items for the next generation of Adiabati: ~ gine in the 6CQ-7OO HP pOI.rer range is continuing, with emphasis on r.ompactness, performance, and manufacturing practicality. An on-going active basic support effort within the Adiabatic Engine Program involv-es "mini!T!UJ\'l :rict.ion" adiabatic technology. 1his engine work emphasizes minimi- zation of friction through the use of components sucl~ a~ gas bearings, "ringless" pistons, low friction ":iry" ceramic bearings and solid lubri- cants. UNCOOLE::J ADIA:8ATIG Srl}INE/5 ':X:JN TRUCK INSTALLA- TION A.!'l early version of adiabati: engine techru:>- logy has been demonstrated in a military 5 ton truck. :iguI'es 5 and 6 show t::e truck as modi- fied to incor~>orate improved aerodynamics, dri- ver visibility, and packaging chara~teristics. Figure 7 show~; the installed wlcooled Adiabatic Engine. Note its uncluttered appearance which results from t.he elimination of 361 individual pieces (FiguN" 8) including the radiator. Advan- tages of the ull1cvoled Adiabatic Engine are listed in Table 1, with listed fuel economy savings a conservative €'stimate based or. full load engine operationo P~crt load truck operation (Wlloaded truck bed) revealed outstanding fuel economy or over 9 miles per gallon during a round trip be- tween Detroit. and Washington DC. The current production military S ton truck utilblir..g the Cummins SHe 2~;o engine averages approximately 6 miles per gallon in 8.n wlloaded test bed coOndi- tion. '!'o date,. t.his Wlcooled Adiabatic r'J1ginel 5 ton truck installation ~as accumulated over :WOO miles of road testing on the highways of the eastern Unit.ed: States with no incidence of rail- uree In addition, the last 50() miles of road testing was stJ:ccessfully accomplished in an over- loaded condition with 13 tons of cargo in the bed. Tables 2 and 3 show characteristics of the UXlcooled Adiabatic Enginee Note th!!.t the engine is based on the current Cummixm NHC 250 engine and utilizes cera!lrlc coatings throughout its com- bustion chamber areas. In addition, an uncooled Adiabatic Engine has been successtUlly endurance tested on a d;;i1'I.!\!OO!!!eter for 250 hours. ,,1.th one third of the t,est at ~l load.. Figures and 10 show coated zil'conia-based pistons and htlad taken t'roeI this engine after 250 hours of operation. 271 Table 1 - Uncooled Adiabatic Engine Advantages • Lifetime Fuel Savings" • Volw.ne Savings (rt.3) • Parts Eliminated • ile~ht Savings (lbs net) • Elimination of Engine Coolant (qts) $7,089 20 361 338 42 "Based on 2500 Hrs of Operation: $1.25 Per Gallon Table 2 - Uncooled Adiabatic Engine Components The follo~ring components are :::oated with plasma sprayed ceramics: Comoonent Coat Surface >PiStons (ductile iron) Piston Dome ·Cylinder Liners (ductile iron) Inside Diameter ·Cylinder Heads (cast iron) Combustion Surface Exhaust Ports Intake Ports Table 3 - Uncooled Adiabatic ::ngine Based on 8urrent 240 HP mlG-250 Engine in ~ilitary 5 Ton Truck • In-line 6 ~ylinder, Turbocharged • 5'" Bore, 6- Stroke, 355 cu. in. Disolacement • 230 Brake Horsepower @ 2100 RPM • FJ.i..mination of '!later Gooling System (Radiator, Fan, ~ater Pump, Hoses, Belts, etc.) • Combustion System Insulation via Cerami: Coatings 1'able 4 - AA750 Adiabatic Engine Specification • 750 3HP @ 3200 RPM • ~iniMumFuel Con~tion: 0.28 Bore x Stroke: ') 1/2" x 4 3/4" o V-8, High Speed Jiesel Configuration • Turbocha.rged ami A.ir-to-air A.1"tercooling • 1'uTboco/!'!OOund ~n.figuratlon ·.dt'· Radial Ift°flo~1 Pmre·r 'furtIine o Intake Ports Outboard of Vee - Jesigned !"or 1'uned Indllction Systtl'lll • Insulate'd Combustion Ch_ber. :::Ylinder Ports, Manifold. and 1'urbi:lIe Housing • Pulse E:!:haust Manifold wit.h Pulse Converter • N~u Cylinder Head Design • Advtlnced Fuel Systetll Design .~ --- ,- Figure 5 - Oncooled Adiabatic Engbe vehicle installation Figure 6 - tlncooled Adiabatic ~ine vehicle instillation 27S ;''igure ry - ~ncooled -'diabatic Engine ~ 3 - SliJ0d.n8t.ed !)l'CdIlction hard~ - I.U'!cooled Adiabatic Engine 279 Figure 9 - Pistons - uncooled Adiabatic Engine (after 250 hr eDlhtrance test) Figure 10 - Cylinder he&i - uucooled Ad1mat.ic ~ (after 250 br eDdurtmee test) AA750 ADIABATIC EOOXNE Work continues on the next generation of Adiabatic Engine, wtth application to tracked combat vehicles in 1~he 600-750 HP raJl8e tar- geted. The effort <:urrently involves designp initial fabrication'l ann basic component devel- optnent. The specif:lcatior.s and configuration of thi~ engine are :shown in Table 4. A prelimi- nary cross-section <)f the AA750 Adiabatic Engine is shown in Figure 11. CGTONEN'J.'S - Basic component development of the AA750 Adiabatic Engine continues, with empha- sis being applied to both monolithic and coated zirconia based mate:rials. Zirconia based materials have been found to be desirable for Adiabatic Engine application because of their exeellent insulatin,g characteristics, adequate strength characteristics, and thermal expansion characteristies 'lihich are relatively close to some metals. A reoresentative cross-section of a single-cyHnder engine used for AA750 compo- nent development is shown in Fig. 12. The com- !>Osite met.al/ceramic approach is used throughout, with ceramic materials generally desigr:ed to operate in a compressive mode. Results utilizing both monolithic and coated zirconia-·based materials have been quite encouragir~ to date, with both types remaining viable options for the final AA7'50 Adiabatic Sngine. ~ - 'larious oiston configurations con- tinue to be evaluated. ?igure 13 shows an interference-fitted partially stabilized zirconia (PSZ) insert rit!!in a ductile iron piston. Fi~ ure 14 shows a second mo:lOlithic PSZ insert \ihich is interference fitted and brazed to a ductile iron piston to Dro~~de more complete insulation of the Diston top_ ?igure 15 shows a thick (0.100 inch) coated ar.d surface treated zirconia based/ductile iron composite piston. ~.r - 'lariotLs li.:1.er conceots continue to be evaluated. ?igtu-e H, sr.O.iS a monolithic pal'-" tially stabilized 2:irconia (PSZ) insert inter- ference fitted -:.nto an iron sleeve. ~. 17 ShOHS '! thi;:k (0.100 inch) and surface treated zirconia oased :;oat.~ aoplied to an iron liIler sleeve. 1:1 addition, '.,ork using a monolithic alulni:1a-iron composite liner continues to be evaluated. ~ :1tl.,~!-££J~n.~..!lll - :'Iork continues in ';.he headface i.l,sulating pJate. valve, valve seat, ", :lIve £;Uide. and p;chaust oort area~. A headface J:atc '([it:. integral valve seats and made of par--. '".:i.ally stabilized ;drconia (PSZ) is shown in ::i.guxe 1S, -.nth ex.~ensive test of this component parti.cularly successful at brake mean effective pressures of UP to 2C'O PSI. The shown headface plate :~as interfe~mce fitted into a metal head .. An installation of PSZ valve inserts into a metal l:ead is shown in Figure 19. with si.;nificant heat transfer reduction mea:ured relative to the ra- ther small ceramic in.su1at~ area of the inserts. Figure 20 shows PSZ valve guides =rrently being evaluated for the AA750 Adiabatic Engine. ~aust port '""rk involves continued 281 evaluation of a zirconia-metal form composite casting in a JDetal cylinder head and an aluminuIII titanate casting (Figure 21) in a metal cylinder head. MINIMUM-FRICTION ADIABATIC EOOlNE An on-going, active, basic support activity for the Adiabat:i.c fugine Program is the "min:f.lmmt-friction" adiabatic engine technology effort. 1his effort emphasizes minimization of friction through the use of components such as gas bearings, "ringless" pistons, low friction "dry" ceramic bearings and solid lubricants. The engirle is projected to incorporat~ all the advsntages of the C'lU'Tent Adiabatic Engine type:;, plus further improve fuel economy to 0.25 LB/flIF-HR (54 percent thermal efficiency) and eliminate the engine oil system. A repre- sentative schematic diagram of this concept is shown in Figure 220 Progress to date has included 1) initial fabrication and rig testing of various piston/lir~r combinations, 2) evalua- tion of low friction bearings, 3) completed design and initiated fabrication of an advsTlced camshaft/valve train concept, and 4) initiation of lIIUlticylinde:r integration of the components discussed above. Initial co~nent integration of the minimum-friction Adiabatic Engine into a multicylinder configuration is scheduled for 1983. Beginning in 1983, this basic support effort will incorporate additional qdvanced de- velopment areas including variable valve train. porting/manifold system, and cylinder block and head. FUTURE PLANS It is important to note that an Adiabatic Engine can be applied to a wide range of mili- tary vehicleS9 ranging from trucks to main battle t811ks. In addition, adiabatic engine technology can be applied commercially to ground vehicles fl"Ol'll trucks to automobiles and to such applications as helicopters, ~ed aircraft, locomotives, marine use, etc. Figure 23 shows projected production avail- ability dates of various spinoffs of adiabatic technology and the fu.el e~OTlomy of these var'iOlls conf~trations9 TUrbocompound diesels have been demonstrated with fuel econ<>li'(Y as sho'lmp and will be available for production in 1985. The US Army has demonstl"ate{f an uncooled engine in 19C2, and it appears that. this type of er\gine .::ould !:Ie available for production by 1987. . 'fhe !'ull Adi&- batic EDgine w:i.th turbocompounding is project.ed to C~ available for production in 1992. These dates cou.ld be accelerated with increased funding levels for applications f1"Ollt autOlllObiles to malll battle tanks, ~md in fact recent accelerated activities oy variou~ internationsl concerns may well prove these ava-:labillty projections to ~ ~mely pessimist::':. '- . ~ Val~a Gu~de Ceramic Intaf(e Manlfoid with Ceram~c "~ Un~ng I ' ! 5ntake Port w!th Ceramic lining ~ Cylinder liner with Ceramic lining Exhaust Port wUh Ceramic lining Valve with ~~ Ceramic Face Head P~ate Ceramic Exhaust Manifold with Ceramic Lining Ceramic Cap AA· 750 Cross Section End View Flgure 11 - AA-750 Gross :luct.ion cnd vi()w , " I 1< '. \ \ \', 1 \; h ,\ I' ,I \ II :1 '\ , " ,} l ,! . -'. -. - - .... . Zirconia Insulated Engine Figure 12 - Zirconia insulated engine Valve Guides Headface Plate Piston Cap Liner Insert .~- .... - --- ---~- Figure 13 - Partially stabilized zirconia/ ductile i ""'lll pist.on (desl,gn 1) -Figure 15 - !~ick (0.100 inch) zirconia coated piston F:lgure 16 - ParUally stabilised airconia/1ron cylinder liner Figure 17 - Thick (0.100 inch) zirconia coated cylinder liner Fi«tU'e 18 - Part.ial~ stabilized zirconia head face with integral valve inserts _1 ________ ... _____________ .. ________________________ _ Fit;!: Figure 19 - Pert.ia1ly stablliaed zirconia valve inserts -, ........ --.... ----, •. ------------............ ------.... ----------------.... ----------------------------------- .-- .--- . .-- Ii PRED~CTED PRODUCTION DATE ADIABATIC ENGINE SPIN-OffS I!:Nr.!NI= g)Rn(!~AM~ ;::.ro 'W-.w,lii I ':i~ II 111'...,.,_ ••••• \;'11_ I I FUEL ECONOMY, ADIABATIC ENGIHE SPIN OfFS I BSFC TIME It. YEARS (INSTAllED) 71 18119 50 81 12 83 14 I~ 86 8, ~8 89 90 91 92 93 94,9~ 9E 97 93!00 OIESEl TUI!80CHARG£D/AfHII COOUD ' - I II ! I 038 , ...... i'-I" I I I iI.l1!1l0CO!llPOUiH) DIESEl L~ 033 I UNCOOUD ENGINE r\ ~~ ~ 032 I L I I ADIABATIC COfiiPOf'lHm I I I ~I,~," I I ! I I I - P!STO~ I 031 -WWI ~'O ~~!m II 030 - !IUD 029 - ACCESSOIlIES. He I' I \ L~!a I l 021S II. i~'\~~ I I fUm AOIAiMHC TURBO/CPO DIESEL II I I 028 I ~iNIMU~ fli!CTlO~ ADIABATIC ENG!NE I I II I I 1111 . ' ! , 0.25 : , i i4l-" ADIABATIC flOGtHE PLUS I III ~~~ __ SOTTOMI~G CYCLE 024 D. START OF PRODUCTION Figure 23 - Predicted production dates Adiabatic ~~ine spin-offs I ... _______ m ____________________________________________________________________________________________________ ___ COKCJlJSION ~rk to date has demonstrated the feasibi- lity of the TAerges as a breakthrclUgh in engine tecr.nologyo The p0- tential of hi€:h performance ceramics in an Adiabatic Engine has only begwl to be explored, with many int£'rnational concerns greatly acceler- ating efforts in this Helda cne should expect continued dra~!atic N:!sults in the area of adiabatic engtne technology to surface on an international scale in the near future. Acknowledgement is made for the valuable contributions made by the TAOOM/Cummins Adiabatic Engine Team. The cooperatton fr·om the various ceramic manufacturers in the lI .. S.A .. , Japan, Gert1UI~. England, and Australia is also acknowl- edged.. The o1rerall support of the Ct:!il.mrl.ns Engine Compa oS and the US Arttfy Tank--Automotive CoimM.nd is genuinely apDreciated. 1. i/. !lryzilc, "Adiabatic :'ZIgine Prograr.:r". N!lt.ional Jepartment of Energy Autotrotive 'l'echnolof~Y MeetirlR. Jearllom, ¥ichigan, 11-14 NoYcmool" 1980. 2. "Ii. 3ryziJc. "Adiabatic ~ine Program". National Jepartment o~ Energy Automotive -:'ect:nolof~Y ~eeting. Jearborn. ¥ichigan. 25-.. 28 October 1931. 3. :... ~lryziJ( and R. Kallio, .. Adiabatic 1'urbo- compound 2ngine Program" 1981 SA.=: Inter- national Congress and ~sition. SAE Faoer ~nocrTO. Jetroit. lIichigan 23-2: ?ebruary 1951. !.. R.!-'. C'gorkiewicz. :'esign alld JeveloOf'ler:t of :ightir.,s "[ehicles, Joubleday and :;Onmany, :;:nc.. ~arden City t New York, n63. 290 -Fabrication, Testing and Brazing of Dispersed-Metal Toughened Alumina An .1.1umiau:n ·)x:i.le ~st"d ~nateridl :hat 2'on- tains ,1ppr()xi:'la::~1\' : '.'01 .. , :i:lt..>lv dic;perst?'d platinum ,)r ~hr'')!'!liu:-:l was :ie·:plnp~~d ~()r :JSe !"l high temperdt'Jr~. ttler~al-shock r~si5tdnt ~l~c- r rica I lnsu lal:ors . Tht>se cOt:lpOS it es .,r·.. produc.'d by hot-pressing '\!2f)1-Pt ,>r-V 201-Cr powd"rs contai;t.i"g :'i·,t.' "':'ft.~r1.t:i..: ?drti\~:e's JbLll'1t,d ':-'1\' i:1 ~itu r~.!du,'::i~)l1 ). ;~l.itl"1U~ .~hi,)r~de )r ,:nr'J- :I1ium :1Ltrat~. :-~e~t:' "':latt'rLI io;: t 1) tk.\ve r.i,sh fractur~ t.:lughness 13bout twL:e that of ":-onven- tion'}l .. lumina. (2) ,ire' <'xc"II.''1t "I<,ctrical insulators (rt~slsti~ity c0~parahle to t~at 0f alliminu:ll ,oxide '3P to dt '.'ast 300'C. (3) art> highly rcsistclnt ~o r~"p't ... titive tht.'r"llat tran- sientg of )00 JC.'..;, (.:.) have ~r,--'ater than g7t 0i thport?·tical d~~n$ity~ .ind (:;) ,lrt.-' ft"adi 1';1 join- ahl>.> ~\' brazing to =tdl ,'ompc)nents. The i:nproved 'tollghnt!ss and t~1t."r:1Jdl shock resi..,tanct! of th""'se ~t~l"ials ~.rt" l'vid\..-.nlly attributable to 'xlth t~le ""'r 11 ;>art icc .... s (that i"'pede and .jiven ~rdcks) .Uld :.:> .1 -nixed morphology ,)f the 1:u~i:I·.1 ~r31.~S :'~d.~ .:50 ,-'~-lu$t.~:i ..:rdck d~flt:ction .H\d ~rJ.n.:hi 'l~. ~Otl-1 vi tht.·St"> :nechani$O->., .:;i;:.ni~i ... '-lnt ~~; :ht'ly :.e.ld ~~) -;t.ible- CTd f ..... ONE '.If THE ~ST SIGNIFlCA~'T FACTORS limiting the CIS">! ~el·arnics in ,;truct'.l',.tt Ipplications is the lJIJ !-racturt! t0ughne-ss Gf tht:>s\.? materials. In >;en< ral. ceramic m.at .... rials are brittle; they fall f~om the eListie pr·opagation of fla .. s or cTaeks with very little. if any. plastic defon~ation ge:lerated at the crack lips. Thus. eeramies fracture ."i th a very small strain 1:0 fai lure and because llttle straln energy is absorbed b<-fore fracture (with the except ion of the transfo,",at lon toughened ceramics and the fi ber reinfol'ced glass- ceramics which contain =all ['>-10 ~m) diameter SiC fibers). A series of Oispersed-~etater fracture toughness and are ~uch nor" thermal-shock resistant than conven- t ional "t"r.l1!lics and are also i"'per»eable to liquids in high t .... mperatllre oxidizing at~osphert",.(1.2) These new materials were d<,veloped :~r use as long-lasting electrical insuhtors '}lId have performed well in large si~ulated pressurized water r.uclear reactors Jur i !lg :.)ss-.)! -("0 .. ) Lint ~xper i:Oc:lt "i ~ However. t~l.'~· ,li.,o :;th)W ?-)t ... ~ntial in valve lent Iy reduc<,d to leave a s:nall amount c)f a very fine dispersion of tough, Juct ite :neta 11 ic pa rt ieles throughout the aic:mina :!'latrix. The di.spe~sed 3etal ;>h,'ses studied to date ~nclude chromiulll. platinum or iron. but 3 w-ide rallge or :netals could be used dep<,ndlng on a ?articular 3pplication. The basic sha;>es Jf the ceramic are fabricated by hot-pressing in a graphite die or ~y pressure- less sintering. The ~~terial can subsequently be joined to ~t5el f or to mt'tal components by brazi ng to llIdke larger or :BOre complex parts. fAIIRICATION The ceramic-metal powders .ire prepared by coat ing the ceramic part icles with a 1I>~tal pre- cursor _ompound, then decompos i ng the precur:ior under conditions that result in fine '1>i.'tal par- ticles dl~?Crsed on the ceramic particle sur- face. Alumina was used in the inlttal work as the :eramic ~trix because it is an electrical insulator, is essentially insoluble in hot water, is resistant to steam corrosion. can be bra~ed to Betals, and is reajily available. Platinum ~~d chromium were extensively tested as the dispersed aetal. and Al203-Pt and Ai20r.(;r coraposites containing about 1 YOl t of finely dispersed ~tal were found to have significantly iaproved thenaal shock resistance. The first step in the production of Al203-Pt composites consists of the formation of a slurry of alumina powder in a methanol solution ~f a soluble platinum compound, PtC14 or H2PtC16 (Fig. 1). The solvent is evaporated with con- tinuous stirring. The platinum compound is reduced ~nth hydrogen, depositing finely dis- persed platinum particles on the Al203 powder. Composite powders made from reagent grade alu- mina or from Alcoa A-17 alumina containing 0. >-1. 5 1101 %: metal \o!ere hot pressed 15 minutes at 1610°C and about 55 MPa to obtain near- theoretical dlensity. Special graphite dies permitted higher pressing pressures that were needed to achieve adequate density with smali.- diameter com~~sites. Fig. 1. Processing flow diagram for Dispersed-~etal Toughened Alumina. Composites of alumina wi th chromium !!letal were prepared and tes ted to provide a less expensJ.ve substitute for platinum-containing material. inc reduction of chromium compounds to the metal is very iifficult and could be accomplished only when an additional reducing agent lias pr,~sent. Paraffin served satisfac- torily in this capacity aud was added in an amount e~ual to one-half the .veight of the chromiu{il cOr£lpound. Ii. solution of paraffin in hexane v.as slurried with the alumina po~er. The heKane W!tS removed by gently heating wi:h stirri'lg. Ttle compound Cr(N03)3'9H20 ~,)s then deposited on the paraffin-coated Al203 po.!der frol1l a -methanol solution by evajiQrating the solvent vith stirring. After the polider appeared dry, it was further dl:'ied in an oven at no·c. ThEl chrO!i1hm nitrate was usually added in arAQUUU equi valent to 2 \It % Cr (-1.1 vol %). Substantial or complete conversion to metal was accoaplished by heating in a hydrogen at.osphere atmospher.e at about 1300°C for 10 min. No deleterious effect of possible residual carbon was detected. Hot pressing conditions for Al203-Cr powders were similar to those for Al203-Pt, (i.e., 1600°C, 10 minutes and 55 HPa.) ~ples of the DHT material are black in color both on the surface and through the body after bot pressing. We observed only a very limited surface reaction (between the graphite die and the powder) that did not extend an appreciable distance into the composite. Hot pressing of Al203-powder with a molybdenum liner isolating the powder from the graphite made no detectable difference in composite prop- erties. Composite pieces with lengths greater than about 13 nlllI were hot pressed with a Grafol.l* liner to facilitate removal from the die. Coiliposi te tubes as large as 47.6 DI1I OD by about 44.5 IDUl long were produced by hot pressing. Hot-pressed bodies 10.2 mm in diameter by 31.7 mM long had no appreciable density gradient. A selection of some of the sizes of the DMT material that have been fabri- cated by hot pressing is shown 11'1 Fig. 2. RESULTS The microstructure of an Al203-Pt composite is shown in Fig. 3. The apparent grains outlined by the platinum particles actually represent agglom-erates of small particles in the original alumina powder. Grain growth occurring during hot pressing causes grain boundaries to sweep past the metal particles leaving the particl~s distributed through the grains. An example of this, along with fa1rly extensive exaggerated gratn growth is shown in the etched Al203-Pt SAmple of Fig. 4(a). Trans- mission electron microscopy (Fig. 4(b)J shows that the platinum particle size is in the range of 0.1---2 \1m. Figure 5(a) shows the microstt'ucture of an Al20)-<:r composite in reflecte·d light and Fig. 5(b) ShO,"1S a transu:is- sion micrograph. The latter illustrates that the chromium particles are occasionally rod- or disk-shaped and are larger on the average than the platinum particles. CONPOSlTE PROPERTIES Tttt:R.HAL SHOCK BEHAVIOR - The t:MT lIJIlterials "'ere orl.81na11y developed aselectrlcal insu1a- tors for ~nsors exposed to the severe thermal transients of a simulated 10ss-of-:oo ant acci- dent in a pressurized water nuclear reactor core. thus, the resistance of these uaterials to thenaa 1 shock _s a very important property. Ilnther than trying to develop data OIl the ther- mal stress l'esistance parameter ATc of these materials, we were forced by constraints in time to use a stople test that was directly related to the initial appliCAtion. Hot-pressed samples were neated in .ur to SOO"C and dropped into "Ia.ter at SO·C. The approdaate rate of cooling, determined by attaching a ther.ocouple to a ~lll speciaen and recording tbe te_perature ---------------- ~Tradeaack.- Uaion Carbide Corporation. ~"""" ... """"""""'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''--'''' .......... . Y-169960 Fig. 2. Hot-pressed samples of rnT alumina before and after _chining. Y-174611 Y-181621 Fig. 3. \s-polished structure of the dispersed-~ _,·t' -W!II toughened alumina (Al203- 1 vol ~ Pt). £-29312 (b) 3 IIIll Fig. ! •. A120)-1 vol % ?t ceralllic. (a) Polished surface etched vitti H3P04 showing mixed Dlicrostructure and (b) transmission electron on{crograph shoWing Pt particles (arrows) and voids (white spots). during quenching with a transient recorder. ~s about OOO°C!s. The helium permeability was measured by cl3l!lping the specimen in the <'!nd of a rubber tube, applying I). 17 ~a (25 psi) heliu ... to the enclosed side, and then GlIOnitorir..,! hellU1l1 leakage. The he:iua permeation was usually detected by observation of bubble formation in ethanol, and in sase c~ses this was qualitatively /,- calibrated by COGpltr!.son with mass spec.trOlllleter aeasurelilent of belha leak rates. The required thermal shock resistance of composites as indi- cated by helium leak tests was arbitrarily set at 5 x 10-7 cg3/s aft<'!r 15 quenches for 10- and 15-mm-diam !>a.lliples. Qu£nched specimens were not used in production of actual sensors. but quenching results were used to evaluate adequacy ~":...-- '~. - "'"'10. ~ :.-. --- --- -- - --~.~~--- Y-178J73 l-J0525 (a) 40 \l1ll 1 1'1g. 5. A1203-1 vol % Cr ceramic. (a) As-polished surface of specimen quenched 50 times, exhib1lting frequently diverted crack (arrovs); and (b) transmission electron micrograph showing faceted Cr part icles (arrows). of other samples hot-pressed in the same opera- tion. M<)st composites produced met thi! theraal shock resistance requirement. Small specimens (3 mm diaa) were not regularly subjected to quenching tests because they consistently passed. lbe thermal shock resistance tests were useful for evaluating the composites in the 10 to 15 ~ size range. A comparison of the thermal shock resistance of these composites with that of coolftercial ceramics, and with alU!llina specimens produced similarly but without the metal dispersion de~onstrated that the composites were significantly superior. This particular thermal shock test determines in effect how much stable rather than catastrophic crack growth occurs during the transient thermal cycling. A variety of conditions can affect stable crack growth during thermal shock. It can he increased by the introduction of :Xlicrc,scopic voids or cracks in the main crack tip 1:one or by localized plastic deformation. The dhpersion of fine metal part ic les which • ave thental. expansion coefficients less than the D'~l<[rix and/or deform plasti..:ally can pro- duce such effects. In Fig. 5(a) a crack =0 be seen in a Al203-Cr composite t!oat has been quener.ed 50 times. The crack gre\l stably and fallo'IJ"d a tortuous \>ath with diversions and splits, finally disappearing frof!! the surface of the s·pecimen. It is evide't that the energy to pl~opagate such a crack must be greatly increased compared ",nh a s,",oother crack in conventional materials without the metal ?3r- ticle dispersion. The moderate amount of exaggerated grain growth observed in these com- posites may also add defects, such as tiny cracks, that further increase the thermal shock r'esistance. Evidence suggests that the metal particles in the composite~ may also increase ther~al shock resistance by plastically deforming. The transmisf'ion micrograph of Al20)-Cr in Fig. 6 ShOllS what appears to be a crack in the ceramic bridged by a chromium particle that ~as extensively deformed plastically. ~CIlA"'ICAL BEHAV:::JR - Although the prin- cipal requirements for the dispersion enhanced ceramics were superior resistance to thermal shock, some of the mate~ial has been charac- terized as to mechanical behavior as 'Jill be discussed below. Although admittedly the results are somewhat preliminary, we think thac the general t=~nds in the data are encouraging i'nough to }ustl::-- :.:>ri' ,'xti'nsive studies ,)n thel'~ w.aterials. A limited test of ~chanical ~trength "'as made by three- and four-point bending tests. The average values obtained for samples .... ith variouq alumina grain sizes 3nd ~rphologies (e.g., large plate-like grains in fine grained matrix) are given in TabLe 1. The breaKing force of the fine grained IllIiltertal 'JaS 700 ~a for the A120rCr (2 \It :t Cr); that for the A.IZ03-Pt was &30 ~a; and that for pure A1 20 3 --------,----.,---------------------------------------------- E-30839 Fig.~. Transmlssi)O electron micrograph of Al20)-Cr showing Cr particle that appears to have heen deform('d dui.ng passage of crack that it bridg .. s. c·.tinder.;. prt.)tJar~d sl'll.ildrly except without ttle _tal dispersion, was 670 ~a. It is cbvlous that chdnges in grain size and :oorpho- logy (i.e., formation of plate-like grains) are detri:n ... otal to th ... fracture strength of the compositt:. ... s. ~o\Jever, as vill be seen later in this' rep()rt, the fracture :oughness of the "lu- mina with :nixed grain !llOrphology is signifi- cant 1 v ~r .. at .. r than that of the fine-grained matt'rL,I. Tabl,'.. Fracture ~tress of alurllna with dnd without jispt."rsec! metal ;X'lrticles Fractur~ stress_ ~3 Grain ~ixed Fio<,'~ ",""dium':- ~rphology ,-\ 12J 3 . '0'01 Cr 7()0 2QO :.60 \: .,')1 "-\1. , ':01 Pt b30 \: '1 Xlr .. • \ "'if) ):!() - -"------ ~- l:'hr<'<, --;>0: ot ~'t\d t('st .)f 3. ,8 '"'> diam c·t! lndel's. . '~~-oul'--plnt !>end t,'st 'oH -2 "'" thick rectangular ':-*rs ground ?,Hallel to long 11th bt'eald ng" stress, the .U ~O)--<::r sample was the strongest. Dtaza,)nd ;>Yl'amld hardness values deter>'titled with a )O-g load are dso contained in Table 2. These values follow the _ order of three-point b['eaking strength, Al203-Cr, Al20 3 (pure), AlZ0 3-Pt. Table 2. Compressive strength and hardness of dispersed-metal toughened ceramic !laterial A120r-l.l vol % Cr A120~. 7 vol % Pt A120J (pure) Zr02 (partially stabilized) Strength (0.002 in./lIIin) (MFa) 3040 2632 2582 aCommerclal material. Diamond pyramid hardness (50-g load) 2311 2137 2158 1280 The 00' alumina ceramics have signifi- cantly greater fracture toughness than cemmer- cial alumina or advanced structural ceramics such as SiC or S13N4' Typical mom temperature fracture toughness values (as determined using appll('d lIlOment double cant.ilever beam specimens) for these new &aterials and some commercial materials are given in Table 3. The '~a lues demonst rate that our materials, al thou~h ~ontaining onlY one vol t or less of dispersed metal. can hav~ significantly superio~ fracture toughness. Table 3. Fracture toughness of dispersed-metal toughe"ed alumina and sollie c01lllRercial structural ceramics Fracture Toughness ~a'::II lf2 ~aterlal Volume t metal Fine ~ixed Comaercial grain $Orphology ,.1,,:2°3 ,.1,,1,0 r-<::r Al~OrPt PSz.. 5i3:\4- SIC 0.7 4.7 , , .... : ~Partlally stabilized ~lrconia. The increased t.oughness delIIonstrated in ~ h~ ~·'ompos i tes could great 1 y enhdnc~ ~h~ \..lSt.2' ~\t c .. riillll.cs 111 stt'uctl\fal applications. L The size of discollt lnult les (flaws or cracks) ..mich control the tenslle st.ren,.:th 18U6t gener,,11 ... be kept very """,,11 in o,"der tl' achieve good sti·e'ngths. Thill 1s seen from the relationship of tensile fracture strength (Of) to fl.,.", s1;!;e (C) and fracture toughness (l(IC)' (l) where Y is a geoa~tric f&ctor. ------~--.--------------------------- For example, for' a typical aluaina ceramic with KIC - 4 HPa • .. lh and with Y assigned a value of 0.8 (typical for al semicircular flaw in flexure) and a fractlllre stress of a 700 HPa (-100 ksi), the crit:l.cal flaw size is only 21 .. m. Producing complE'x ceramic components while maintaining flaw SiZE' below such a small value is extremely difficult, and the problem is complicated further by the lack of nondestruc- t ive examinat ion (NDf:) techniques capllble of readily detecting su<:h SJIIall defects even in simple shapes. One can see fro~1 Eq. (1), however., tha t if a material's fracturE' toughness (KIC ) can be doubled, the allowable discontinuity size is increased by four th~es while maintaining the same fracture strength. Thus, increasing KIC has a very practical advantage in that these larger fla>ls are much more K"eadily detectable. For exanple, if all values for the alumina ceramic considered above are the sall'le except that: KIC m 8 !'fi'a'mlh, the criti<:al flaw size is increased to a more readily attainable (and detectable) 84 \1m. 2. Associated ".nth the above, ceramic materie.ls with enhanced toughness could be used at higher service stresses (because of higher f,·acture strengths) if components were produced >lith small flaws that were detected by i~proved )jDE technique". If t in the case of the ceramic wi th KIC = 8 )tPa·!Jl fl, discontinuities can be shown to be less than 21 \1m, then the tensile fracture strength will be )1400 !'U'a ()200 k.si). This would a11olo1 the material to be used at .. signifi- cantly higher <;ervice stress or provide a greater working margin between service stress and :rac- ture at rength. 3. In addition IOOst, if not all, ceramics are susceptible to the slow growth of cracks at applied stres'>es well below th"ir fractur" "trength~. The rate of flaw growth hcreases until fal lure occurs, either as :~l<' lpplied stress approaches the fracture s[ren~th or as the length of the flaw increases In size 4t f llced low .1pplled st ress. This ;>rOCt'55 controls the time tD cause failure !n a ~0C ponent at applied static stresses less than the fracture strength. Sy Increasing the fracture toughness of the mat.erial one ~an increase the .:;tr~ss !t?'vel at .. hi..::'!, .;uch ~l.)tJ .:ra("" ··t~ :l'J.!its the 11feti_ '~f a component. PHYSICAL PROPERTIES - There are only ~ i",ited data on the physical properties or the jigp,'rsion toughened ceramics. The therlllal expansion of .... 120rCr (l.1 V<'l :) is little changed from that of !U20). In the telllperature range of room telllpe,~ature to l()OO·C ... value 0f S.7 • lO-b/C .... s obtained. Electrical retl t stance !Ae'asuretlwn t s up to ;'00 9 C s.hoved t ht' resistivity was invN'sel~' pro port ion.31 to the :!leta I ~ntent (e.g., the "12°)-. n; l't had a f).7": lover resIstIvity th.n pur .. U;!O). The thenll"t ,::oMuctlv1t:t of the cerset lIay show the 91aIU~' ~ffect :>f .. sllEht increase With _tal content. We have I1I()t perfonaed ",xtenslve l:>nlll- term stability tests on the composite materials. However a sample held 516 h at 940'C in air showed no deterioration in resistance to thermal shock and very little cbange in microstructure. BRAZING OF CERAMICS -. One of the key tech- nologies that viII enbance or restrict the use of ceramic ~teria18 1n high performance appli- cations (e.g., beat engines or advanced heat exchangers) is the ability to reliably join Simple-shape cOlllpanents to form complex assemblies or to join unit lengths of material to form large systems. Although by careful selection of location or through judicious deslgn a joint in such applications may not be requlred to withstand the full lntenslty of the various service conditions (such as temperature or stress) as the bulk ceramic material itself, it is of course highly desirable that a ceraJilic-to·-ceramic: or ceramic-to-metal joint be capable of operation at near peak conditions. Unfortunately, although ceramic joining tech- nology bas been highly developed over the past f lfty years or so, :DOst ::If the effort has been expended in developing _terials and techniques for applications that will see service at "low" temperatures and vith low structural require- ~ents. The development of technology for joining ~eramics for ube at elevated tempera- tures, at ~igh stress levels, and In dirty "nv 1 ronment s has !>ee:l very li.1li ted. At least three techniques appear to have at least some promise for joining of ceramics In high perfOr!lll- tions It ~~ramtc hr.azi:'lii: ~v ~1rst lppl'~·!,g \ ~etal:lc ~oatlng :0 the ~eraDl~ .ubstrate ~nd brazing to this. coat i"ll with .\ ,'"nvent t"nal :ill<,r _tal. The '''ry.t' "ol •• I .. ~rdAl ,-ectOJic-t)- :let.!i ~ ..... .:t! t"dustr"., .ttl.! '"l..~n\· ,A:r,:-!"rou!~· \;,~~: - ,- .. i t l0ns .lr~ hase-d ·)0 :~ ~:; ':: t.'e.: !'ln0: .)~y. ~or.~ rt.'ct>nt ly .:l numb~r :,f rE"s~arch~rs ~Voe .!'"!'\'t:.l':\.)i:'~'..! :1l1"r "",tal" (b&sed ,)II lICtl',e :setal tddltl}ns. that ~t some ct!rami.: utoerials .:Hr~ct: .... ,.,lthout the !)jCed for "recoat.lng ... nd laS ',lSerl ~::I ·oh. !arlle :luml:><-r .>i the :HT ,oluml"" :.",Su;.H,)r~ :-)[,) :~ .. -/arioas s.en$or :;ubass~Rb~i~s 'ihown ::1 r~!~. 'll r",ct ~a"l ng .woids ~!>e j.ev~ l,,»_nt .nd .lppllcat ion vi what \S ~:t :!tanv : ... "e5 .• "",rv ,;ophlsticated .:oating ·)r ~talliz1ng :r ..... t»e1t. .uso the bond "trengthhnd ~orrosi"n r"slstanc .. .1\ .. .:oatlng ioes :lOt 'la"" :0 .~ .If ,·Ol\c .. rn. Filler _t .. ls ,&S~d ·or Hrect ~r .. dng (4. those llsl!'d ~t) ~r,ue "r .. coated :er .... ic,.) will ~ ... \er .. ll v ~~ ... , __ am __ .. ,· __________________ ~ __ ~ ________________________________________________ ~ 8485-80 Fig. 7. Typical bl'azed sensor subassemblies incorporating dispersed-platinum toughened alumina insulators (black IMterial in photo' 'lOt have the .)x!dat ion resistance of :Mny high purity .:t>ramics .It th~ir ~xi'llum service tem- peratures, but uf course ~ny commercial ceram- ics must operate at lower temperatures because of the eifect <.>n properties of densificatioll or 3intering aids. On :he other hand bra:ing of .,eramL:s In general is in many cases ude diff!cul: hv the ~ismatch between coefficients of ther~al expansion of the ceramic and the generailv ~tallic ('iller _tal. ·lt~t' :.:",1 ~indr~nce to direct brazing of cerdmlcs is the fact that only a very few filler a.er .• l s that wi 11 wet ,eram!cs are so Id cOWller- c1.11:·.·. :-'lus in lIOst cases these iUlportant 'Ill ... r.; H" :!/.ade !>,. the user cODpany or lal>o1'a- :::.)r'" . -:-~'" · ... t t I ng behavior of .. liquId (braze ,il:0V\ 'n .• ~olid (ceranic in this case) is jt.~pt.·~)dll.·:1~ )t1 th£" '!lu.rfac~ e'nerg) :)of the SOlld. ~ht.· ";;'Jr~:l-'~ t~nsivn of the !iquid. and the ~.) ~ i j - :: 1'1 i j lnterLH'C ia 1 energy. n .. c pilenol.tena ,I ",,'tt '''~, spreading and adhesion of :!IOlten ",ate-r, .:" >nto !>:.!bs,tt'ates havo? been s~udled -·X~·' ~ ... ~ .t· ... ~hrough the'lears. ;"ri!Bclrily usil\g :~'" "'-'5$~:'" 1rop ~,thod.( 3.".~) n",se and )tr"r ~O!s ... "'Lher'" have sholl'tl thdt although many OIIetal'L: "1,,.,,'nts by the;aselves will !'loOt wet dnd :lOn~ :0 ceramlc II'lfHerlals • ..,."ttlng can be Pl'olllot",d ~\' the "ddi1tion of speclfic alloying e-lellfH~nts, :t is h'portant to note that for" brliize .1110:", to ~ "'",cc"s5ful- it i!1 'lOt !nlf- ficletlt th<.It .. 150 that the solid- liquid interfacial ",nergy bo! dotereased. Thus 1aproyed lletting <:6,11 slv.sys be o:.btalned by clecreasing the inte'rfaclal _rgy ..,ld .y be obtairwd i.n soue C/I.lles by deerea!l1llj~ the sur-' face ten.lon of the· Uquld. 297 Ooe of the 80st beneficial eleaents added to brazing filler .etals to proeote wetting of ceraaics has been titsniua. Titanium and other reactive metals such as zirconium and hafnium evidently aid in wett1ng aDd adhesion by decreasing the interfacial energy ratber than by changing the surface tension of the 801ten filler. This change in interfacial energy is brought about by the reaction of the titanium or (other reactive .etal) vith the surface oxygen atoms (in the case of an oxide ceram1c) so the degree of adhesion is a function of the free energy of OXide forsation AFof of the additive. Thus the most beneficial brazing filler metal additions are those trat are strong oxide formers (for brazing of ox1de cer8lllics) o~ strong carbide forlllers in the case of carbon-base ceramics. The sensors shovn in Figure 7 were made possible by a unique ceramic-to-metal seal syste. based upon both the dispersed-metal toughened alumina insulator and an experimental brazing filler metal also developed at this laboratory. This sea 1 sys tem has been show" to be resistant to at least 100 h exposure ~o 700·C (1470°F) steam, and repetitive thermal transients of )DO·C/s. For example. film sensor subasseu,b11es (one Is ident 1 f led by an ~rrow In Fig. 7) containing a relatively large plat inum-dispersion toughened ceramic insulator (12,7 ~ dlam) typically have helium leak rates of 10-6 cn3 's-1 or less after 35 such theraal transients. The sessile drop apparatus shown In Fig. 8 is being used 1:0 evalute the vettlnt behavior of experimental brazing filler metals on various substrates. ntis particular Wilt uses induction heating with the ceramic substrate enclosed in a tantalum susceptor. Typical results fro .. this apparatus are shown in Flg. 9 for the 49 ti-4'1 Cu-2Be filler setal that was ultima- tely used to hr.aze all of the high teapt"' Hure sensors shown in Figure 7. The sesslle drop Witt 1s prescnt ly heing used in ~~r task to develop a ftller ..,tal for brazing of partially stabilized zirconia tv the ductile iron lD~tallic components for olle version of an adiabatic diesel engine. Work is "ls~ uf\dcrvay on a high temperature. oxidat ton resistant alloy for brazing of sUtcon carbide. Both efforts are s JOISTS .- ~ traditional ~nglneerin& app~Galch to design of fall safe structul'es has been the use of ~onser" vatlve no&lna1 stresses. Hovever, too often the exist.nco of a critical de-fect bas resulted in catastrophic failure. Therefore. the evaluation of fracture mechanics has becoae increasingly important N the designer. and IIoI!thods of &wllytically describing the l'ea1sltance of a aater1.1 to fracture have been developed. Bnu,o joints a,re gener41ly designed on the basis of shear' strength data, but it is our contentioQ tMt _ny joints are loaded in 4354-82 Fig. 8. Sellslle drop apparatus used to IIIOnitor the \letting behavior of experimental brazing filler mt!tals as a funct ion ~f time, tempera ture and atmosphere. Fig. 9. Sess ile drop of 49T! -49Cu-2Be t>>tperiltental brSl!ing fUler """tal on a substrate elf Al20rl vol t Pt. __ , ____________________ w_,w' _____________________ __ 4350-82 Fig. 10. Arc 1I!Ieilter used to fabricate slII&ll quantities of experil\)~~ntal brazing ftller metals. tension at least part of their lives 5«) that it is important to know how they behave under those conditions. Braze joints by their nature contain flavs that under crack-opening (tensile) conditions could lead to unexpected failure. IOe have rec,ently initiated an effort to utilize fracture .:aechanics analyses to study the fracture behavior of ~raze joints between ceraaic base ~terlals and to develop data on the critical stress illtenslty factor. KIC' in such brazements. The spec-imen used in measuring the fracture toughness of the brazed joints is the sallie as that used for the bulk ceralllic--the appUed moment double cant ilever beam (AMDCB). The cos- posite specimen is made by brazing together two hot pressed ceramic bars such that the resultillg brs7.e joint is located in what eventually becomes the c€'lUter of the AHlleS spec imen. Ien in Table 4. the crit ica 1 fracture toughness. KIC' of the brazed samples was ~_ le&st as high as that for alumina ceramics. In aIlcsses. the crack propagated pri&arily in the bral:c _tal. l'lle c<,nunic-lUeta 1 interface did not control the braze joint toughness. n,e fracture toughness values sU!l.@:e,;l ·that 1n many cases the br8Ee joint did not dltdnish _chanicll1 perfor- SlBnce of th~ system ;~lgn1ficant ly. If at all. Table 4. Critical fracture toughness values for braze joints in cera.ica Syat_ AIZO]/Ti 'Cu'Bel AlZO] AIZO]-o.7% Ptl Tl 'Cu'Be/A120)- 0.7% Ft REFERENCES KIC ' KPa·.~ Locus of fracture 4.Z ! O.Z Braze I18terial 4.7 Braze _terial 1. A. J. Moorhead, C. S. Horgan. J. J. WOodhouse and R. W. Reed, "Brazing of Sensors for Rlgh- Temperature Steam Instrumentation Systems." Welding Journill. (Miami) 60(4), April 1981, pp. l7-Z8. 2. C. S. Horgan, A. J. ~rhead, and R. J. Lauf, "TIler_l-Shoci. Resistant Alumina-Meta 1 Cenaet Insulators,- Ceramic Bulletin. (Ohio) 61(9) September 19&1, pp. 974-81. 3. R. M. Cllspln and M. ~icholas, -TIle Wetting and Bonding Behavior of Some Nickel Alloy-Alumina Systeas,- J. of Mater. Sci. 11: 17-Z1 (1976). 4. C. R. Kurkjian and W. D. Kingery. "Surface Tens ion at Elevated Temperatures," J. ~ys. Che",. 60(7): % l-{)3 (1956). 5. B. C. Allen and W. O. Kingery, "Surface Teosion and Contact Angle in Some Liquid Metal-Solid Ceraaic Systeos at Elevated Temperatures.- AIME Trans. 215(2): 3~-36 (1959). :.tesearch ~p()nsored ~y the I)fffcl~ "f ~~uc!~~tr Re~ul.Hory Research. LS. \'ucledr ~e.:u!,It"r\' Commission under Interagenc" .. h:reement :l(1E ':'O-5)1-7~ and th.~ c. S. :lepartlll<'nt <>f ':ner.:\,. undel~ ,'ontract ""-w"-:''''05-en£-."\1, 'Wit~ t~1t .. \ :-;)1\)n (.:lrhid~ Ct.lcporat il..'Ifl. I [)USTRY PERSPEClrlVES PANEL. DISCUSSION -,. --_._ .. ------ ---.---~- INDUSTRY PERSPECTIVES PANEL DISCUSSION A special pane" session was convened on Wednesday afternoon, October 27, 1982, during the Twentieth Autanotive Technology Development Contractors I Coord'i nati on meeti ng. The purpose of the panel discussion was to obtain feedback from certai n sectors of the industry on past DOE achievements a~d for possible future consideration in its program planning. The sessior. took the form of a panel d'i scussi on wi th maximum audi ence particip~tion. Dr. David E. Cole, Professor at the University of Michigan and President o~ Applied Theory Incorporated (ATl) served as moderator and chairman of the session. Panel members were selected from pertinent allied industries. The expressed opinions, however, were their own, and do not reflect their affiliations. Professionals serving on the panel were: Harold Brock, Private Consultant - John Deere Corporation, Waterloo, Iowa; Llaire Eatock, Pratt and Wh;tney of Can~da, longveuie, Quebec; J03 Wicto'- Suski, American Trucking Associations, Washington, D.C.; Al Bellin, General Electric Corporation, lynn, Massachusetts; John Fobian, American Automobile Association, Falls Church, Virginia: Stan Greene, General Aviation Manufacturers Association, Washington, D.C. Subjects of discussion were centered around the followi~J topics: Research and development emphasis Program deSign and management Information and technology transfer Future scenario and requirements Positive feedback was received at this meeting and marty pertinent technical discussions also took place. These topics will be the subject of a planned separate SAE publication. ALTERI'JA"rIVI: FUELS I SE~SSION :t..'.' t,":' ,l,:" . t: • ...! ....... ;. ••. t.' ; : '. ln~! \\..~ '-:-I..'r:l.1r ~ t'n\~ 1:11.-' " .. 1S I ::~: ' ... 1 .... . \.'''': :.1.. , • -. I ".:":: Utilization of Alternative Fuels in a Diesel Engine , , s. S. l~tz. S. M. Geyer. and M. J. Jacobus The Pennsylvaflla State Univ. lod '-· ... r::p iI..' St.;'! ! ue ~ So I::', h , • ill~/.!inl:. ?oi.';!":':~"rizatit'n ,!;Jrint! ..,t~"~lLt'. ::i..:h ·:is,,-·,J:o,;i.t\" :eddin~ t ... ' ;'l..','r It,~r:'li::,lti,'n d.nJ in\ .':-." ~lt}te l..','mbustion, .lnd ~l"wb': l:lUs:n.: ~~':'.-::'lt:'ri.~_i- ,\ r!, 'll <..; tJ~: i t i ',·t· '"l . '.,:It:1 :i:::itt'd ..;u .... ·Cl"'SS ;\1 ;q·"t11e:::~ .lre :h.t St''.·t' [I.." ... ·nl1lh.:h ~, :--rt:";t,'nt ::It' :"'t' ,:t.·...:t,.·~ . .lb:.l..· dl~: .. In ~' ... ·I..'r.:I..':-h·: ..;!t·,:.st: 'r!~. - _ .... : \~ ... ' . : ..: ' ..: I. •• : I.. ~ .. • L \ !" :... :~ ..... ' _ . :' t' ~ , t t : ~ ~' ..... :. -. 17':"' :.t: .... ;' .. t', t :I..':-"! l: .,;.'1..', •••.. 1:-' ;. _\. \: : :1..' I. : t :h .... · .• ·' ... -.. ~: ,:.: ".: I.. ;- ... " • • \ •• : I...~ -:- ~.':h':'l.. r :. \-,- t.... ;"'t· : -" ,.::::, " ::..:: :h: .... : ...... , .l:t 301 '~,'u:-;t:r ... ; l:l~: '~"',":';"~;:'. -:1 .: '" : \..' ... : t t,.' U :': .. ;' 'I.' r ~ ~ e .... :'~e~~nt~J .~ \~~tT'~:X ,\, !"t,'~cntt'\;' ::! : l~ .. t· .- ... ::: I .'. In...:: :.. ~.~t.·ntl" .t:: ,·,'ns~(tl.!lt:rlt :\'~ :~t.'"\" ~l.l': .... - :"h'!. ':"r .... ":1 :'rt'St~nt'l;'''': • Table 1 - Comparative ~Iulticyl inder Enp,ine Test Data for 1720 RPM Rack 1/4 1/2 3/4 Full ,,.," FUEL DF-K DF'-2* DF-M DF-2 DF-M OF-2 OF-M OF-2 - BH?c (HP) 15.4 14.5 40.5 39.7 64.8 62.1 68.5 68.2 THEFF (X) 20.3 19.2 30.0 29.2 29.9 28.9 29.8 27.9 BSEC (BTU/HPUR) 12555 13235 8480 8102 8503 8797 8557 9113 AF 56.2 60.6 32.4 33.1 19.7 20.3 18.9 18.3 ~ 0.266 0.246 0.46 . i 0.451 0.76 0.135 0.19 0.815 co (X) 0.032 0.020 0.020 0.019 0.030 0.030 0.055 0.039 CO2 (X) 3.72 :J.60 6.81 6.54 11.53 :'0.53 12.10 11.64 NO (PPM) 90 91 190 199 260 256 250 253 NO (PPM) x 105 104 220 223 210 26~ 265 258 HC (PPM) 10 63 53 45 100 318 100 51 O2 (X) 17.5 Ij,,6 14.0 12.8 8.0 7.8 6.0 5.6 MO - Table ~ - Comparat ive ~lulticY[inJer ~ngine Test Data for :000 RP~! - - Rack 1/4 1/2 :~/4 Full • FUEL DUPe (RP) THEFF (X) DSEC (BTUI AF CO (X) CO2 CI:) NO (PPM) !:0x (PPM) Ile (PPM) 'liPRR) DF-M 10.7 13.1 16659 67.8 0.220 0.042 3.29 45 79 125 19.5 - DF-2'" DF-M ---r-' 12.5 39.6 Hi.2 26.7 15710 9515 68.3 34.7 0.219 0.430 0.029 0.022 3.42 6.18 61 163 72 1.95 91 38 16.9 14.7 - All OF-I values _lre from Ref. 10, ?p. 98-i05. -------- !--.. DF-2 DF-M DF-2 DF-M DF-2 40.6 65.1 65.7 76.0 11.5 27.3 29.0 29.2 28.5 29.0 9316 8770 8707 89' ) 8783 35.2 23.6 22.0 18.5 18.6 0.424 O.GH 0.680 0.004 0.804 0.019 0.016 O.OH 0.029 0.038 6.O-fa 9.54 9.43 11.11 11.79 188 216 267 275 210 206 292 274 28.5 274 50 83 129 70 69 13.4 10.0 8.4 7.0 5.6 - o-"~ ," N 1. " 0- OF-1 " .- _. ~ El , E .3 , ~: :6 1- ~ ! --+-----~r_----_+I--- eo '0 ., '0 . . w "t I .0 -c , i ... ' , L~ ~ . / .. ft '. tL':ls. \t": ',-'(' ·Z?~~~ th~ ::l~r:aal efficienc~' IL'r DF-~ ,~i~ ' .. LIS ":t":;er~:t~~\· s ll-.:ht 1 .. ' hi..~r\er than for ~r-~L t..~~':l\·l':>;t:':· ... the ~H·->t :laJ a. sli~htly higher ::ltr":li. l:~-~~'it!~1"':': ~- .. 'r _iii. LICk st.'tti.n~s ~lt 1720 :\,:)~~. 1:~'!-:·t,:":l'J. )t~~\~l.· h .. )rst.:pl.. ...... ·er ~·I.,llQwed the S...i;:~l..' :"2~.lLi. ':t.' ~l :"7-t.'l"L'nCeS .IS therm':ll efficiency. :::-\,-~·~~t ;" ~r :':1t? : ... :\ac~~ ~\.!OC R.p~t "':I...'nditi"n, dif- 't:'ft'!h."e:-, l~e .:t~ner~:;.ll:; !.~ss than b ;lercent which . _ .• '--~ l' ::It.:'ret,'!I.:. :~h- ~l!~,t,ti':t.:' ,jif:-t!renc~s presentt: .... d ~lere Shvl.:...! ::\.'\t :-t? ~'0nsiJen.?d ":I..")nclusivc. .-\ more Je[Jil~d s~n~!~-c~linder ~ngine ~tudv has been und~rt.l~~:l tL~ ~t~j\- th~se Jifi~r~nces ~0re fully. . "'.m,'s [~st :'esult:i .1.5 .. iell a:i the SL)F for all l)artLc111Lit~ :-t~uap~e::i ire ;~r~s~ntcd in l"J.ble 3. S t dnda rd .;e\" Ll t 1. ,'tlS .1 rt.' ;.' r~s .... nt t2'd ", .. here ?0SSS i b l~ • but . .; ... 'C'tt· ,'r these results .lre :'ds~d .... 'n d small n.umber \.'q" ~a:npl~s _. ,~s 1\.'· ... · ~lS I.)nly two; con- sequentlv. ~are :;hould ~e exercised when inter- pretin.; these jatJ. :n ,Ill ~3S'~S. the .-\:nes results i,lr ;)1'-:-1 .m.:! ;)F-~ c'verlJp .... lthin ,1tH~ standard deviation. ~ndicating no sihnificant measurabl~ difference; however, in all cases. the J09 DF-M did result in a lower mean value. The soluble organic fraction was consistently higher for DF-M than for OF-2, but again dif- ferences are not statistically significant. r---~---------,---------,---------.-----, .\00 :SIJ ~~~ / ':JE) f :J- ",-~ - / ! / 0- 0,·2 I z ~ )1) 1 /1 :r;;J -1 $ i i );) J 1----1 ;. ~so i '-t \ 1 I I , .. ': ... .) , zi ., '~ \ ..; \ \ .. JII) \ \ f It '1 I I .., '",, ___ ~ /1 I '1 ~ / I '1 ' \~I~ --,--j FL,. 2 - 2000 RP~! Emission Data Comparison DESCRIPTIOll A."D RESl'LTS OF VECnABLE OIL TESTS The objectives for this phase of the project are as follows: 1. Establish a baseline for the engine on JF-2 USing three load conditions at ~:'OO RP~ • 2. At each load co:tdition for sunflowerseed uil, cottonseed oil, soybean oil, and peanut oil. _,brain performance data and ?as-phase emission dat a tor CO, HC. ~Ox, and total aldehydes. Compare .these data with that obtained for the baseline . 3. Collect exhaust particulate matter at each load condition to document the biological activity of th'~se solid-phase emissions. The single-cylinder direct-injected Diesel engine (Avco-Bernard W-51, 0.36 ,) being used for this phase of the study is fully instrumented to ;>rovide performan';e ·.lata (12,13). The instru- ,.,entation consists jf: Table 3 - Comparative Multicy~inder Engine Particulate Data ~ 1/2 RACK, 1720 RPM 1/2 RACK, 2000 RPM 3/4 RACK, 2000 RPM FUEL DF-H DF-2 DF-H DF-2 DF-H DF-2 f-. .. - ~' ~ S.)luble I I Organic 4).0 30.3 + 6.9 57.1 + 7.6 40.2 + 11.6 10.9 + 0.9 7.5 :f: : • 5 Fract ion - - - - (%) , I - ~ I I Ames Test I Results of 0.9'1 + 0.29 0.99 0.61 + 0.25 0.77 + 0.18 1. 32 :f: 0.05 1. 75 + 0.6 .. - - .. , SOF* L I I ------' L..-. *Ames test results using TA98, slope at 100 micrograt"ls per plate + std. dey. 1. Thennocouples mounted at strategic loca- tions on the engine. 2. Transd'lcers mounted on the engine to sense needle lift, timing, and cylinder ?ressure. 3. On-line gas phase instrumentation con- sisting of a Beckman :nodel 955 heated chemilumin- escent analyzl=r for oxides of nitrogen, a Beckman ruodel 86!, infrared analyzer for CO, 3. Beckman model IR-l5A infrared analvzer for CO~, a Beckman model 7:'1 for 02. and a Be~kman :nodel~109 un- heated FlO for HC. Aldehydes are 2011ec:ed using the D~PH IT!ethod outlined in Appendix B. rhe outputs from the transducers are re- corded on floppy discs using a ~icolet ~xplorer I, I "'emorv oscilloscope for documentaticn i'pd fcrther processing. A comparison of selected fuel properties is ,;iven'in Appendix A. Shololn in Figs. 3 and:' are typical ~r~ssure dod needle lift traces comparing JF-2 to cottonseed oil ,C:,O) performance. ..\t 1/3 rack, the dii ferences are more pronounced than dt the higher rack settings since the CSO is bllrning. later in the cycle_ [n this engine~ 3$ evidenced by the pressure traces presented, the cc)mbustion is smoother with vegetable viI than wi th :JF-2. H;~nce, this could be one reason why slightly hlgh.=r thermal efficiencies are expe- rienced with vegetable oils, 3S shown in fig. 5. The equivalence ratio is slightly higher for the vegetable oila because of the difrerences in heat- ing values 01 the fuels combined with differences in the stoichiometry. The smaller heat ing values of the vegetable coils tend to decrease their 310 actual air-fuel ratio and the theoretical air- fuel ratio is also lower; these two factors ~.':"_ bine to give an overall increase in the e~ui~ alence ratio. l I j i n.';. 3 - Comparative DF-2 and Cottonseed 0il "res- sure .mci. ~ecdle U.i~ Tril.cnq It 1/3 Rack. 2:'00 'U'~! r-r-' , -12.<1 1000 · soo "- · bOO · · 0. -00 · ." C -;: ~oo L-J-__ ~ __ L-~'_~~--L __ ~ __ LJ :'}o ::0 ~O ~0 )0 ex )0 '0 Fig. :. - Comparative DF-2 and Cottonseed ,lil Pressure and Xeedle Lift Traces at 2/3 Rack, 2400 RP~t ,- "r I I - "r - ! ~ I- - ~----------~----.-----~-------------r--l -i,... , L ! , I 'r- --~----------.-~-- Fig~ S - Si.ngl~-I...·\·linder :'n:r;in~ ?cri0n:J.anc~ Com- parative !)ata -, I 1 311 The comparatiYe eaission data are shown in Fig. 6 and Table~. Generally. the gas-phase emissions for the rvo vegetable oils tested are sli~tly higher. However, in the case ~f SO~ a~ 2/3.and full rack and total aldehydes a~ all rack settings, thc!~ vegetable oils show signii- i~tly higher v~lues. Particulate mass loadin~ rates increase fOI~ the vegetable oils. This is "lost pronounced al: the full rack condiLCion. Based upon a limited n~ber of tests on the SOF. the !liological aCI:ivitv as assayed bv ~he Ames test is lower for ~egetable oils than ror the baseline DF-2. Sl~\RY Tr~s program :as just completed its fifth year. During the :irst four years. alDOSt all activity centered "'?On alcohol utilization in light-duty Diesel engines. Sinc~ al~o~ls ~ave s~c~ poor cetane numbers. it ~as realized that in t~ ~~sence of an aLtive ignition system and or =jor engine ::lc..aifi.:ations that ourning these fuels neat was not ?Ossible. The ~oal Jf the ?rog:-.:mt ... as not to deve:0p new nardware. !>ut :-ather ~~ inv€sti~a~e n0W the alcJhols ~ght 1 ------+--... -:-----:--1 J -------"--.---.--------.---.----~~ --------------------------.~-~-~ :i~ .. "!' - Singl~-__.:·:li!.)der ::n~lne ~:~issi ... 'n _".'c:!- ::>arat!ve Jat,l Table:' - ComparaUve :;ingle--:dinder r:ngine Particulate and Total Aldehvde Data I 1 . !~. I ... ' .. ~ . .: ~ .~.'" ... : t') '. .' j .~:: '~ ...... " L '. . i '--------'-------'---------' 7:tJl: ot-n .... r-,cv tnp\.,l( !I::-! ·' ..... tl.;:u~ .. toe .!ccop • .l'll!l eo ~ .. a· ,,, ...... \f-";I~rcent Ul('~ :~'H • ~~" MAn hest be utiliz~d ~y th~ ?resent ~enerati0n L. ~n~ines. rhereiore. it ~as J~~iJed that the 'licch01s w8uld be handl~j .is fuel ~xtenders ~nd :h.:lt the :!lode ,'Ii :.ntr,~-.!!.!.:::.i ... "In w,-)~lJ be via ftt::-:.i·- ~..lt ll..'tl .. )urin~ th~ (v'JT!::-:' ,,-edT. ?rc'.:;r..un t!!"1phasis ~e~dn to shiit in two r~spects. ~irst, iu~ls ,~ther than ~he alcoho_s ... ~re :lQ\o1 ~~in~ ~0n sider~d~ Jnd second, :~~ ~ui:J-up ~i 3 nedt- 11~ .. )h01" Ji t!S~ 1-1 ike t:n~:' ne tt.:'st : d~ i ~ i t~· .... ·.15 :'e~un. Shale "i:" ... ,,,',L .. -{':t..:'ri-;ed 'i 1s" .10.1 ~3ri0us ~~~et3bl~ }i:3 ~~~~ s~l~~:~d ~0r t~$~~~~. :~e ~n~in~ ~uilJ-up ~:~~l~ts ~,i .1 sin~le ~vliIlder ~itt~J with : re~0~db:~ ~~ac 0i ~ither J: .. 'r ~:)l ,,-·,'niL.:ur.lti .. "n .J.~ll..! ...in .h,ti\"e ii.rliti...:n :;\·$t~ffi .. ~l\~ ~~~0r findings ~i this ~tudv to j~\t~ have bt.?t.·n: :) that .... hi :t.~ ~ .. lc\..'1hl. ... l : Ll'J"ti .. ~dt i .. ~n ~:.:'t?s r~Juc~ t~lt"~ :"'!,lSS "! ~Id.rti .. ·ulate "'l,atter :-vrmed .. t!·.t!' ~: ... '~i\..tl\O~t':. _1$ t~::,_i\'t .. :": -:-~: :~~ O\..~~S :-~st ... : : .. t~: t:~~ t..lW ?d.rti~i..ll .. \te :!1at:er iUJ. ..:anic fra.ct i ...... n is enhanced J.nd its :;:t\)iuble ,"'1'- ::'i 5-,~nerall'" .. :he ~uni~ati\..'n .. "f .lque'-Hls .il...: .... ~h'-"l JChrades ~ni;ir~e ?~rf0nnanc~ ;r':'l.duallv · ..•. nti~ th~ ... ~ns~t vi ·· .. ~t :nisiire" i::; cnc,-..,untt~re·d; ~his s.~~ms tL" ~ ... 'rreL;.tc rea~"o"'nabl\' ·.,1~lt with ::-te (}umbt:!r .. 't ~at~r :':l01t!cuJ..~~$ lon the t!X.hduSt ?t"C"duct5 ~;nd ~h~ :dtt?'nt he,lt ,-'t- ~ht' ~ll(:\.)h(" :-· ... atet"-fuel ':: .:vmbiud.tl,-)n supplic-J to the engin~_ For the ve~etat)le ~l:S tested ~hus f~r 'sun- : 1 v ... -erseed .lnd cot [('ns",ed). ~here .lppears [.' :,e "",all fuel-ener~y .lnd :'ic,a..::tivin· Hi~·.lnt.l"es .... hen cOi!lPdr~d ... ·ith :Ir-.! .llt~vu~n the p .. irticul..lt~ ~..;s ... 'l:erfor:nith! ~:'" :'i,'- lo£i~al dssays report~d ~erc. 1. "The :\l)l~ ~)f S\'ntheti~ :=-uels :':1 ~r.C' rnited St ..ltes Eneri!Y ~~ut~r~, II :,xx,-"'n C .. "'Ir'P,,-"!'r.1t i ~=::: '.'!av 1"80)" tive ~ue! !)r0~rams," Fuels and ~ubric3nts ~~P,i~: ~ent, General ~0t0rs R~se~r~h Lab0r3t"ri~$. :":03 nen. .'II (19;:1)" J. "Alternative Fuels f()r ~t~dium-Sp~i'd Jiese 1 Engines ~ro~~rar.1 .. If Southwest Resen. ~~ .• ct 1: .• "'!::i: l:" :\~t'in~J ~-r,-'1r: :lJ.l',lht"'-i: ~~,l:e ~"i: .. ~'. :) ..... !~-::.: Fuels lInd Lubri.::ants !{psearch L .. lbl-'r:ltcoc.-. :-::""R:. San Ant0ni0. TX 119811. ). "The Bi\.d\."'I\!L.:al Liquid rut!ls .-\lt~;:1.1- tive re~hn010~y Status and En£ineerin~ C0nsiJ~~ - t i.,-~ns"'f A Tech~i"':.ll Rep,,-"rt :leveL.)ped thrc':'l.:h ..\:-;.-\E's Pub11t..: :~.)l i..:v Issues !'n")~l' .. L."r: •• \S:\E ~. :\.l)rlls.. A... ~(\U~(."ti.s .In.! L~u\'J .. "?\'11\~cri!..ltil'n ,~:- ':e..:ctable .. 'ils ..... l'h~~. En~. Jept .• rni~er~i:~ _,~ :Jdho .. ~~sc~~. , : ':J8~'. .\..:r. ~·~n..:. :.',~ u';t~. :.....; 4 :1. ',':nrrt.·S':'il.·:~ :"'::1iti...1 n ~:n&:1.:'!~~~·· :_~uiSl.lna ~tdt~ ~'ni\'~rsi:~~ ?~t.~' ·"~'~l::. ~ .. '. )nJ.. ~ "~\ttcmj)ts t ... ~ :·'rl':\°t.:!nt ::1~~"'::":'r ( ... ~f.:.i:l~ '. .. i:.~ :':~::l- :-: .. ''*'\:,!," ,.1i: ~\' :~nl.!inc ~k'''':~:lo .. ·,1t! ... '''ns .1nJ :'~h!.I. ,\JJiti\'~s:' \~r. ~~nk!. Ji·: .• J~part~~nt .. ~:. ,\~r" ~lnc ~~i..:;h~ri~s .. Si~vert .. 'n .. S\..,uth. A:·ri("l ,:Q8': 1 ,lnct R~ £. '!';lshil1. ·'~!t:!thdr.,-'.i Fu~ii.J.ti\.\n ,-': ..1 _.~..:::: j\.lty Au: ... ~m\::. : ... e Ji~st!: ~:1.~ln~~" ?reslI?llte'd _It ::~t:' SAE :~ut.!!...~"" ~~tbri"""1nts ~t~etinh .. 3 .. 1itimore. ~" ,,-,t l"ber : Q80. ?aper .lppcodrs i n .~:_~Q~~_~e_~~~.~~...: Labri(3nts - A ~~rs£ec~ive 0n t~e future. ~AE ~~'" 7: t :-';~"\;~;-b~-; : 980>-:--··-----··-------- :0, ~r,-1ukhi\·.1n.:':~:--!.~. 1:1 . ...1 :'_ S. :"c.:st~. H~'he FlJ.m.i~!.lt ion ,-'t Alcl~"'h{.'l in .J Li:"tht :tutv .-\ut ... "cu't iv\.' Jic$~l ::n~int!:' ~ASA Rep\."lrt \.,.·Rlb-9t;. , '~8n. 3roukhiyan. ~~ ~~ H. dnd S. 5. ~~stz. "Etha~(:l Fun\i~ .. \tb~'n .. 'f .1 ~i~ht Dutv .. \ut.~n:(-,tive Jiese l "Il!t in..:!." ? aper :'1: :09 present eJ .it SA[ c'uel s .\0 LubricJ.nts 'lt~eti~. ruls.a. ,)\(. ,)ctvber 1981. Paper lppears il1l Alt~.!!1_~e Fuels_~,~r Oiesel~ngine_s., SAE SP50) (October 1981 \. 1.2. Heise\", ;. O. and S. S. Lestz, "Periorr:lance .l.nd r.missi0ns Characteristics ~'f Aqueous Alcohol FUt!ls in a 01 Diesel Engi"e," ~ASA Report CR1.b7H; 11982). APP"~D[X .\ 1 J. He isev, .J" B. and S. S. Lestz, "Aqueous Alcohol Fumi~ation of .1 Sin~le-Cylinder Dl Diesel Engine," Paper 811208 presented ..It SAE Fuels" Lubricants :1eetin~. Tulsa, 11K, October 1981. Paper appears in Alternate Fuels for Diesel ~~nes, SAE SPSO f70ctober -19811.----- Selected Fuel Properties ~ DF-2 DF-~I Propertv * .. - LHV (BTt:;~br:d 19197 18318 t-- Densi t:' (lbmi.;,tl) 7.05 6.96 - Init 1.11 Boiling 420 ~1)2 Point ( "F) - -- Final Bollin~ 640 ,9, P,'lnt i ()F\ - (~. t .H.1t:" " ~i'l ~y ~ St,.'i...:~l~~'"7:~:r:,· 1 , 1:'.0 , - .---------Valu~s ~r~'~ ~~l~ :"::"~l~~ ~0u~~~~: A-~. ~u.~l ~'-.l~;,~~~~,~ :\-~ . 6ist .::.iiti .... ,tl ',":-\l: ',:",t.~~:-' ::h' ~ 3 ... " .... ',} :\.3t ... "n. FL ------------ - - ~ (1.981' '. :\-) ~ ,~be rt. =~. ~'., :_~~t_~~~~~_~~~lb~st ~:"ln E~~~~~ ~.!..:~~ __ :\~.: __ :.1_~~:_~_':2~~_[~ I ~! .. l:-;Jer .inJ R0W :'u:'l.ish~rs .. SC\J Y,.)r~ \ :9~ 3! ~. .;:Jt·h.\'de ~~lJlpl.t::$ havt' :'t:.~en ..:ollected ~n .. -'~ the 5in'l!le-~~;lirH.1~r t!n~ine :or Di~sel fuel ~1S t.:tell as ,.:()tt\."'nse~d ,.)i1 .. uld sun ,,"lil. The alde- hydes ~r~ ~01:~~t~d ~v ~ubblin~ the ~xhaust ~as thr\..lugn ~l $\.""Ilutl.. . .,n ,-'I .2-.:., jinitrcphC'n:,:lh~·dra.zine (D:\l'H). This c.1uses th", hi"hlv reactive alde- hydes L> form their o.'\PH -Ierivates ... hich have a ru~ch higher ~olecular ... ~i~ht and hav", greater stability. After ~,'llectL)I\. solid D!\PH deriva- tives ..Ire filtered out =J remaini~ derivatives which are in solution are extract~d using pentane. following extraction. the solid precipitate and 313 - Sunflowerseed Cottonseed 011 Oil 15907 15 9 41 7.69 7.63 . -420 '·:a20 Cracks Cr.h:ks 17 ii'l 13.7 l l. ~ I ~xtracted derivatives are combined dnd dnal\"zed ~ravim~trically [0 ~'btdin an indi~atiun ~i t0tal ..11deh~·de ~·missions •. \5 fllund i.n \,ther liter.lture .. the total aldehydes are ceported .15 ::tg formalde- hyde per ~ubic foot exhaust. This was generallY reasonable since formaldehvde accounted for :O-Q0: ,,: the ,1ldehvdes present (B-1, B-2). He'",ever, there is evidence that the material analvzed gravimetrica 11 y conl: ains :nore than .iust aldehvde- ;)~PH deriv,ltives (B--1). t',>r this reason. the values presented dre likely to be t~o high; C0n- sequently, a ,o:as chromatograph has been set up to analyze indiVidual aldehvde derivatill'es to "btain a more accurate indication 0f aldehvde emissi.oDS. P:-elimittar,· indications have 5ho""1 that for alde'lyde emissions from DF-2 and vege- table oils, formaldehyde is ,~ much lower "ercen't- age of the total than the 7(}-90:: reported by others for g,lsoline and methane>!' This could cause further errors in measuring total aldehydes as equivalent formaldehvde. REFERESCES 8-1. Adt, R. R., eI: .11., "Characterization ,H' Alcohol/Gasoline Bl~'nds as Automotive Fuel - Performance and Emissions Characteristics," Department of ~echanical Engineering, L'niversitv of ~iami. Coral Gables, FL (September 1981). B-2, Oberclorfer. P. E., "The Determinat ion of .... 1dehvdes in Automobile Exaust Gas," SAE ?aper ~o. 670123 lJanuarv 1967). 314 ----~---- ---------------------- ---~-.- QUESTION AND ANSWER PERIOD Q: Bill Peters. Ricardo. One question. Were your oils raw oils or were they esters? A: Excuse me sir. Q: Were the vegetable oils raw vegetable oils or had they been esterized? A: All tests reported here were with the raw vegetable oils; however, we plan to do some tests wIlet'e we are goi ng to take one of the oils ~en we finish the tests (Ille will find out wIlich one appears to have the biggest problem) and we are going to try ourselves to run it through an esterification proce$s and look at that. That probably will be the extent of what we will do to try and adjust. the composition. Q: My naIle is Lynn of CUlll'llins. 1 would like to I3dke a strong plea fOt, future lrogratmle. \Jith the latter :'u,!l. it ,houL .1150 !:>e noted that the de~ree 0f injection advance required to clear ::Iisfire at light load, rated speed .1pproach .... the subjective noise threshold. The lack of any subjective noise increase with the Ol diesel when running on the low ignition quality diesel fuel prov,~-d somewhat surprising. The inaccuracv (Jf subject'ive assessment should however be noted. Preliminary analysis of the 101 diesel combustion diagrar.!S broadly supports the $ubjective assessments made. It should also he n0ted that in the case of the rDI diesel. all Jf the test .. ork ·.rith the very I.,,", ignltl0n qualitv :uels was carried (Jut with a relatively otif: single e~'lindcr en[:ine '.;hid! tencts t,) ::lask noise trends. It must be c(Jnc!uded without access to :urt'ler data that low igniti0n qualit:: fuels will impose 3 noise penalt" in diesel combustion systems. This requi res ~ont inued research with both IDI and 01 variants. d) Fuel Injection Equil>ment - During the ;)ro\~ramm~. " fuel h.~ndling system :L'r the $uppTession 0i :'\lel "apour '.-ith vol.ttilt! :u",)s'.ras utd ized .AI though this arrangement \oMS successfully emplo~'ed on sE"veral of the combust ion sys tems throughout the progr anull.:!. apparent vapour problems were encountered during the Task 3 01 tests. The problem arose when running vith the predominantly naphthaiD-c blend and resulted in severe instability 0i the dynamic injection timing and fuelling level through~ut the operating range. Data was not ,ollected with this fuel therefore and it was assumed that s:milar problems would have been preva~ent with naphtha. TIle reasons for this problem are not fully underst.wd but it may be signifi,~ant that o)f •• 11 the combustion systems examined, the 01 diesel bas a relatively higher rate injection pump which may be a contributing factor. Performance and Emissions - a) !DI diesel - 'oTith this combustion system, He penalties were evident with low ignition quality fuels. Penalties were however restricted to high speed over the load range with straight run naphtha and low speed with the alternative diesel fuel. In the latter case the response was most significant and particulate emissions were also influenced adversely. These penalties were observed when advancing the injection timing to clear misfire. Retarding the timing largely overcame the emissions penalty towards the higher load factors at the expense of ligl~t load misfire. In the important consideration of fuel consUlllption. adverse e,ffects relative to 0-2 operation ranging bet~reen c. 3-11% were apparent. the Ulagni~ude being de,pendent upon fuel. speed and load. The i:nportalllce of these consumption penalties requires close review when studying the trade-off between the production costs of lower quality fuels and vehicle economy. b) DI diesel - Preliminary analysis suggests that the major fuel effect in the 01 d iese I was increased stooke at low speed wi th the alternative low igniti,on quality diesel fuel. This trend penalised ,articulates and available torque. SPARK IGNITED STRATIFIED CHARGE CO~USTION SYST~~S - As expected with positive ignition. the stratified charge sysl:ems evaluated have proved generally fuel tolerant but problem areas may be summarised as fol1.,ws:- Operabd i t,Y - a) Rated speed - Wi th high ignition quality fueh of c. :'0+ cetane number. the XAN P! system incurred combustion problems at high sreerl sig!1.ifi::3.~tly limiting the dvailable sreed range. In this case. spark ~~ntrol was lc~t dnd heavy detonation occurred at ra ted spe! j (:'000 rev Imin) ",i th load ~ac tors in excess jf .:.". S bar B.'I£P. Realistic torque was 0nl~' re, tored wh'en reducing the rated speed to lo\{ levels (c. 3000 rev/min) not ~(>Ilnnensurate ",ith light dut\" applications. With the spark ignited, indirect injection (SIIUI) engine, spark management of the engine · ... as not obtained with 0-2 at high load, high :i?t'~d~ rt.'sultini!, in unstable~ eratil..': combustion. ThIS ,ould 0nly be ~\"ercOlue :,V reducing the rdted speed 0n this i",,1 to h)w levels similar ~J that "f the ~{'\N F~t systl"rr. ',/ith .. 11 ~ther iuels in these combustion s\"steos, useable r.Hed speeds of c ... 000 rev/min (0uld bl" achieved up to relatively high lo.d ia,-tors. The .lbsence ~f dny problems with the :"X..lCO TeeS ,,'stem in this respect rei lects "ne ,)I th" =jor Jifi",rences between the systems i ..... the rees utilizes a vel-y high en~rgy. ",ui t i -st r l"e igni t i on source timed simu 1 taneous I\" .. nth th., inje,·tion .In,d therefore ignites the . ",,,t , !ul"l spray, l\"'iding prl"-mixing, S.,U- 19niti,'n and detonation. ''''ith the F"!-t and SIIDI, th ... TCCS phil0sophy (dllnot be .lchieved bv 319 advancing the spark towards the front of the injection period since the relatively low energy, single strike ignition source does not successfully ignite the spray. presumably due to plug wetting. b) Light load - With the FM and SIIDl systems very light load stable combustion freouently proved difficult to achieve. The experience of others suggests that this is not a fundamental characteristic of the systems but reflects the very limited development status of the actual engines tested. ~} Spark plug life - The SlID! engine could not be run on naphtha at the lower speeds owing to rapid spark plug sooting and loss of correct ignition causing misfire and unstable running. Frequent spark plug failures were also encountered on all fuels with this system but it is reasoned that a fundamental design change to reduce the length of the electrodes whilst preserving the position of the gap within the pre-chamber may overc~me this problem. With the FM system, running with detonation must be avoided or spark plug failures result whilst in the TeeS system, spark plug failures were not recorded but high rates of electrode erosion were encountered, Whilst design/development should overcome these problems. the harsh environment for sparking plugs within the stratified charge engine should be noted. Performance and Emissions - rnlike th~ diesel engine W1tn a unique reterence fuel. the influence of fuels upon performance and emissions with the multi-fuel. stratified charge engine is not so readily interpreted in a succinct manner. For all fuels. performance and emission trends were generally distinctly defined but in the case of the o?en chamber systems (FM and TeeS) it may be stated that there is a preference for the more volatile fuels. Such fuels encourage lower smoke 3.nd greater torque. I.'hi 1st such fuels do not ~verall assist in reducing the high He characteristics of these systems, they do ... nable in conjunction with the smoke trends. lower pdrticulates to be 3.chieved. It is believed that with volatile fuels. lighter He species are formed not conducive to particulate formation. In the case of fuel eC"nomy. volatile ' .. els l'E'tllrned the best consumption at high load f3.ctors ~ut this was not 3lwavs reflected at 1 i ~~i1t load. DISCUSSIO!" For the purposes of this overview. the discussion is restricted to the identification of likt."'lv .:andidate ~oro':nlstlon s,·stt"f::ts for future fuel gro~ps. ~ithin each fuel g~oup ttc likl"lv .:andidate ':Oinbustion system., 3rE.' revie'lol~d based "pall two sc .. :~arioS: - relaxed environmental pressure with cOtlrpariSoll of baseline .:hancteristics using optimum econom" tlmlng plan: and continued stringent environmental st·andards. .. ;;.,; .. :;:~;.;" '. HIGH IG~nTlON Qll,\LITY DIESEl. AI'll BROAl'CUT fUELS - tuels ot c.40+ cetane number ignition quality are considered here. For fuels of this class, it is j'Jdged that the diesel will remain dominant with hot and cold operability not presenting a major problem. When considering economy, the DI diesel has a c.IO% advantage over the IDI and this wi 11 be an important consideration in the overall energy b~lance since high ignition quality fuels will be more costly to produce. Ihe 01 does however have lower torque potential than the 101 and higher baseline emission characteristics. With relaxed environmental pressurt>, it may be assumed that the selection of 01 or 101 would depend upon individual requirements between economy and torque. Contiaued development of the 01 should result in improved torque although lhe use of the high pressure fuel injection equipment required will increase first costs. In this context, uther 01 SystE:ms. such as the :-lAN Controlled Direct Injection (COl) system appear prumising. With maintained stringent emission .:ontful". the 101 is likely to rem.ain dominant uwing to luwer baseline emission .:haractcristics ,'ompared with the DI. Even in this case. particulate emiss iuns n~1y present d probl~tn in the longer term. The multi-spray 01 system evaluated Jur~n~ thi.s t)rtJgr..ltnItlC is unlikely to ..ll'hit.·\'~ ~ngineering He. ~Ox and pdrti"ulate tdrgets LUmmensurate "ith future legislation even when using such technolugy as valve covering orific" aozzles (VeO) .. The spark ignited stratified charge engine is not thought to represent a .:andidate for fuels ,'1 this class.. With such fuels only the TeeS svst"m may be considered as the other two systems ~valuated (P.-I .. ll\d SIlOI) generally encountered .:>pet'ability p;roblems in respect of rated speed. The TeeS system. however, exhibits significantly higher baseline HC and particulate emissions and lUN turque chgracteristi.:s with respect to either the 101 or DI aiesel and its adoption fur such fuels is nut thought to be justified. ~:-'t' rr. ... ~I·~II...'~~ Ct'I\J . .LTY ~~·\rHTP..A A.'\D BR(\\D- }'L"ELS - IL1 thIS .:lass. fuels ,)f -:.35 ur lvwer cetane number ,..l,re Lonsidered. \I."h~n "xamining the baseline characteristics of the 101 cliesel 1,/ith these fuels. the emissions and Jvail.lbl" turque .:haracterlstics did not overall rcpr~l$t:'nt ..1 r:\.J.jor problem ar~.:1 relative to D-~ ... '?\:?t..it t....'n ..is r~i~renc~. lnstJ.nct.~$ vf 'v/orst..' ~(: ... )numy wer~ however noted .. Doubt ",ust ho .... ever "xist ior the IDl diesel ... ·ith tuels ,·f this .:lass based upon thr"e ~easons - cold operabi lity. tolerance to retard for ICM ~Ox i[1 res!>"ct of misfire and noise. '';ith lu .... baseline emissions. high torque and .... id" sp~ed r:mge in .:onjullction .... ith the "ncouraging rt),;ul ts from this progratlll1l .... research should be ~n~(}ur..lged to ~ce wh~tht!r th~ aforementil..")ned problems and the instances of worse economy may !>e u>l>! rcome by deve 1 opllloi!n t . It mus t howeve r be r"cugnised th . .tt the suitability of the IDl dies"l in ..:onjunct lun· wi th ve lOY low i gni t ion qual i ty iuel~ will !>e seriously in doubt with .:ontinued stringent emissions standards requiring injection retard for low ~Ox. In this case mis- fire regimes .ne likely. with sharp He trade- of f responses. Since the 01 diesel was not evaluated on this d ass "f fue I for the reason previously mentioned. the long term suitabi 1 ity of the 01 diesel cannot be ascertained and resort to speclllatilln wi II not be made. With positive ignition the spark ignited stratified charge engine is able to avoid the cold operability etc. type of problem tholt will fa.:e the 10I diesel. The achievements of the TeeS system in these respects ~.ave been well reported in the past and it fi reaslOned that with equivalent develop."'lent effort. the F!-! and SIlDI system should be c_lpat-le of similar performance. Spark ignited str~tified charge engines must clearly represent candidates ther ... fore for fuels of this class. Based upon this program:ne. the sUlt~bility of the S[[OI cannot be fully ascertained uwing to the rapid spark plug foulin~ with naphtha as fuel. Of the two open chamber systems examined (~ and TeeS) bvth have good I ight load ,'conomy characteristics. Overall. the f~ perfonned better with low ... r He emissions and particulates. better torque and lower high load consumpt ion. Bilst.·l inc ~OX ~miss ions '."f;: re however ~ .. Jmewnat higher th.lIl the TCeS systt!'m pr~sumabl .... due tl1 tue It air pre-mixing prior to i ltli tiun. ;"'hi I 5t the 10'ler He emi 53 ions of the F~ compared with the leeS are fundamental owing to the use of a pintle type of injector. an overall judge_llt of the selection of candidate between the F~! and TeeS is wi theld for two reasons as follows:- Firstly. the r~ system was evaluated in single cyl inder fonn. Whi 1st the frict i,'n factors utilized to predict multi-cylinder P.-I performance fer .:amparison with the observed multi-cylinder TeeS dat) are entirely credible. the basic single cylinder performance m.w he ed"lt1ced owing to the lack of any cyl inder tc> cylinder distribution problem of air flow. s .... irl or injection/ignition timing. Secondly. the single cyiinder F!-I engine had excellent volur.>etric efficiency .:('mpared with the Iv'" breathing effici .... c:1 L·f the "''hite TeeS engine. Required therefore. for a full understanding. are comprehensive multi-cylinder programmes comparing P.-I and TeeS systems with equivalent. well developed breathing ~haracteristi.:s • ultimately employing appropriate natural injection/ignition timing plans. What is clear is that either of the two systems \Jill have overall higher haseline ellussions and lOloler torque compared with the 101 diel'>el. Furthermore. the 02'xtensive emissions cuntrols required for _ontinued string ... nt emission standards are likely to significantly erode the favourablo2' light 1l1ad baseline ~conoroy ~hara<..teristics ,'f t'te two systeillS. ln this .:ontext. the SIIDI system is worthy of continued ,·valuation. Although as expo2'cted its fue 1 "conomy ,characterist ics are not as good as those oi the open chamber design. the limited available evidence from this programme suggests tha,t the He response overall is lower, approaching more closely thac: of the 101 diesel. Because e,f this, the differential in fuel economy trends; between pre and oper. chamber systems may bE' narrowed when controlling emissiooslo stringent levels. LOW -lGNITION QUAI.ITY DIESEL FUEL .• Addressed here .Ue fuels of c. 3~, cetane number ignition quality, high aromati(: content and c.7000F end 1'0 int. Such fuels have proved p.-oblematical in ,he lOr diesel progratlDC ""ing to the misfire/ HC/particulate trade-offs prevalent at light load, low speed and dKscussed earlier in this present'lt ion. In thi:; case, and somewhat surprisingly, the 01 diesel appeared IOOre tolerant with similar misfire regimes not being encountered. Corroborative suppvrt fram the screening study was obtained when comparing 10101 speed HC trends b.aween the 101 .~nd 01 diesels with the low ignition quality 0-2 fuel tested. In this cas.e HC emissions were significantly elevated with the 101 diesel but remained more typical of 0-2 operation in toe Dl. This class of fuel also caused significant starting difficulties at typical laboratory ambient tempera:ures in the 101 diesel even campared wi th t he lower igni t i on qua 1 i ty naphtha type foels. Such data support :he fr'-"'luently exploited volatility/ignition quality trade-off in respect of starting. At the time of writing, starting tests have not been undertaken in the 01 diesel although it is anticipated that the results will not be encouraging with this class of fuel. In addition. 1010 speed torque with the OJ diesel was further curtailed with the law ignition quality diesel fuel due to a marked increase in smoke at highel load factors. Outside of n .. " aforementioned problem areas, !>aseline emissions and performance of the 101 .md 01 diesels generJ,lly remained competitive with the 0-2 reference data. This would encourage further research although the suitability of the diesel, particularly of th~ 101, does not se~m a!isured based upon the available evidence with fuels of this class. Io:ith maintained environmental pressures. retarding for low NOll wi 11 further thi s suspicion as starting problems will be exacerbated, further misfire regimes encountered and marked emission trade-off penalties incur' ed. In this case, the continued use of the diese. is thought unlikely. The FM and Tces combustion systens would appear suited to such fuels as they were successfully evaluat"d wi th good 1 ight load ecooOllI}' trends and cold starting and no apparent operability problems.. Their inclusion in a future scenario utilizing such fuels would therefore a.ppear jusltified although baseline emissioos"ill be high. In this context, it should be noted that the superior He Characteristics of the FH compared with the Tecs were lost at 10" speed with this t)~e of fuel, 321 presumably due to the adverse influence of the less volatile fuel upon mixing and evaporation fram the wall of the combustion chamber under the low bowl swirl conditions prevalent 'It low speed. Compared with the demonstrated a.bility of the 101 diesel with such fuels, the torque curve of either the FM or TeeS systems ..,ill also be lower as a consequence of their inclusion tc avoid operabi 1 i ty problelll5. Since these types of fuel further increase the He and particulate ~3U5sions ~n the ~ system and particulates in the TCeS, the demands upon ~mission5 controls for maintained stringent standards will be increased. Again, this is likely to erode or nulifv the favourable baseline economy trends ~f these systems. For budgetary reasons, the low ignition quality diesel fuel was not evaluated in the SllDI system and with spark ignition the systems suitability for such fuels nav only !>e speculated. Such a system should again :'e examined in the continued research programmes required for j :~i: understanding, in particular, when ~omparing \Je;: developed multi-cylinder ~ and TeeS svstems for the reasons previously discussed. CO~CLrS!ONS C"-"DlDAn: C(Y.o'IBl'STIO); SYSTE.'tl FOR Fr7\'"RE FTELS Relaxed Environmental Standards - a) High Ignition Quality Diesei and Broad- cut Fuels - 101 and D1 diesel b) Low Igniti.on Quality );aphtha d.i.d Broad- cut F,,;:is - Spark ignited strati :ied <'Ilarge or 101 diesel providing potential cold operability and noise ,roblems can be ')v~·rcome by development in the interests of ~nimising baseline emissions and maximising torque availability. c) Low Ignition Qualitv Diesel Fue!s - Spark ignited stratified charge or adapti.'d rl'1.' 01 diesel providing cold operability etc. problems are not insu\-erable. ~aintai~ed Stri~gent Emissions Standards - a.l Hi gil 19t'i t ion Qual i ty D{e~-;nd B:-,'ari- cut Fuels - 101 diesel. b) LJV Ignition Quallty ~aphtha and Broa,1- cut Fu~ls - Spark ignited stratified charge. e) Low Ignition Quality Diesel Fuels - Spark ignited stratified charge. OVERALL - The interactic'n :'et·ole",n fuels and engines is c,x"plelt requlri:1!~ "Xt"nslve research from structured progra9~s for. a full understanding. During these progra.wnes. the follcruing areas must '>e addressed:- a) Candidate Sy~fuels b) !DI and D1 diesel develop!llent in respect of cold operabi lity, noise and tolerance to retara ",ith low ignition quality fuels. c} Well develvped, multi-q'linder stratified charge comparisons. d) Other combust ion svste\llS, i. e. "re-chamber ID1 diesel and M&~ eDI 01 diesel. e) Combustion systems with different cylinder si~es, speed ranges and methods of aspiration. As dic«,ted by the above progr.:umues, the det ai led "P t i.r.li sat i on LO f p rami sing comb inat ions must be carri.ed LOUt. APPENDIX 1 Sasic Specification of Test Fuels - Task 2 -- Fuel Cetane Distillation OF No ISP 10% 50% 90% f''Bi' - Phillips 0-·2 48 378 432 50S 568 603 -I So%l SO% w< /-< 44 298 313 381 613 666 Diese1/Nap~tha 66%/34% wt/wt 47.5 306 324 435 617 676 Diesel/Naphtha - Phillips [}-2 38 363 426 502 565 601 "0.12% T.E.L. '--I Philli.ps D>-2 51 363 '-30 I 502 565 603 I "0.2% I.P.S. l - .- NB 1) The diesel used for [h~ above diesel/naphtha blends is not Phillips 0-2 but selected high cetane European diesel fuels. 2) The above blending naphthas are not the SF 10;: 50r. 90'Z FBP - .. 32 505 568 b03 - 248 ':'78 565 599 208 2119 ::+:. ._- ---19b !37 -_·------1 -+---.- I I i -. Aromatic Content ": "01 30.3 25 Effective Values of Evaporation Constant for Hydrocarbon Fuel Drops . ...lJl.&=i'RAt'T I Exrt.'ri;:lt.-·n:'l~ :.J.iit:':-> l't ~v(lpOr,ltiun "':...JIlSt..lnt / flo)[ U!")t: i:1 .... ~,l,,~ddt idnS ... '! ~·\.'dP0r....lti ... Hl r,ites anJ Jrl)p li!·t.:ti.::c,:-i lr~ t.lirl:; ~PdrSL' ..1111..1 .Ir ... ' '~lsuall:/ ... ·lHlt int.'tl : ... ' ,,-,,In,Ji~ tdt1S ll[ ":i.teaJy-state evapor.:l- t i\'n ':1 -i'.it..':-i .... 'L'lH :-1ixt Ur"t..'S ..l.: :lL)r:~.dl at7tospheric pre.s~;Jrt:. ~':h.' :!lain \)b it!\,.:t iVt! l)f ~ht.~ present :..;: ,.d\" ~ . ..., :\' .' ''. l~:t· "t"~: ~' .... :: ';L''' \,11Lt.:::. ~)I L'Y~i{) \'r...Jt:".':l .... l);:.:-,:,c~~ :'l~i:' ,,-0·:t.'r "."iUt: r •. Hl~t..'S vI dr:aoi- L'nt ,llr i1fc:-.::->Ufl:, :t:mper.iturt.· ,1:lJ '.'clucity, all~ · ... ·i~i(h ,11:. ... ' :~l;':'t..' ~:ltu d.LI...· ... llUlt ~t~t..> ini luencc vi tnt.:' :i~.J.t-, .. fJ ~·'-"ri\.)~l 1:1 10""·t.'ri:l~ the tJverall t!vap- llLlti ... )11 ;.ite. ::~t..' .1'.;eragt.! boiling point (50 t-h:r .... e;1t r'l.'I...,·· .. t.:'r(~·....: 1 i~ the ph: .. ~il...·cll property :-it.:l~I..:~t..'\.: : ... , .... : • ..t:·J.,:~t..:rl:c ::It..' ·/ol.:.lt ility of th~ :"el. ------- :·:;;U''';;.:.;\,·'_ 'T',:r. Ji«Ji' ,:\'APllRATllJ~ is v:' prime ::np\lr:.l::'t..· .•. .' .;t.':.;:.~n ..1nJ ~h:rivrman1..:t.: .'t- . "4~~ l .... -· ... t-' ~ .... t."-...1 ,':::b'_~~~ i,':l ...;~'stc::ls. in...: IuJ ing In ~i prt..'vious ;~.ij. t..'r .~: :~.'::: ~'-'!1 · ..... 1.::> :.\.~t.:~.;..s~,-'J vn tht! cfft;ct:; .:;i.O:L::~ ·:t·'=';"''-.irt.' ,1:1"": :t.:'::npt:rJ.turt! \.'11 thl.' ...,:1..·.h;·.- ... :,~:t..' t. .. ;.i;'1..'r .... ll i." .. ':1 ,': :·.;.,-~i JrL1ps • ..\ nu- :-:-.\.r~,.i~ ~r,' ... t.."...:urt..· \<;~i:-i Jt...'s...:ribed for l...dl(:ul.J.ting ...,:t..",l~~'''-'''':'_l::'l.. ·.·,d~..:t'.'"> I; ~:r""t'-Sur~ ... h':c t('mpl.~rdture;:"" i:" ... ; 1..·".1l),I:-_il ~,ln ":I..Hlst..lnt ~ ~lr1d th~ nK!thod W'dS .1. ,: ~·\"l:::':':;t· : ::t..' t.":d~,'rJ.t il..Hl ... 'h.lr..lCtt..'[.- ':-':·~·t)(.,1:lt.'~ ,l\'i~tlv~l ~..l~'_)li:H;~, iP ... , . \:10...1 .::t.·::>\..·1 ... '1: \.~'F~) 1:'1 ,uit.·sccnt ~ltmo- '"-..\'\.t..!-::~:~": :::t..' "'::..<[..it i,-'!~ ... ~:. :ht...4 :l~.:lt-up ~erilhj in :~lt'~ "-.", t.·':~lpl..'r,ltlun wert:' :-:>tudit.:>u analytically ,Hll.l .j,n 't.~~iLldt iv~l : ,'r \..-:jt 1;n.,it in~ t~lC Jur ... lt i0tl t,)f ::tt.' .It..' ... ~!..- .... ;~ :~:l,'~t..· .... ...1.'"> "':'\:t i\·t...~J. l:rdphs were p:'t!- ';eIlted "'£1 len ~;hY .. ·t.·d. ;-.1..)1" ~\.~lc'l.."led f j~ls., the ~ifects ,>t ..lir ?r~~sur~. temr~ratur~ dIld vei0c- in' •. mJ :',,<,1 In'p ~i~". "n ::." length vi the I1C .. H-Up ?t.~ri ... ")J .jIll! ,)n tnt! L.l!. i0 vt" the heat-up ;)\.~ri\.1ti tv th~ t,)t<11 Jrop lift·ti:!lt>. It was sho_'T1 "'Sur.:tbt!rs in pJ.r,!ntilcst;"s Jt.'si~iJte refl."'reIh."eS dt "nJ vI ;>ap.,r. J. S. Chin BeijiTl\; In of the heat-up period can lead to serious errors in the calculation vf drop evap- ,!ration rates and drop lifetimes. The extent of this error, and its dependence on drop size and .1lIlbient air conditions, was demonstrated quanti- tatively for several fuels. The :nain drawba.::k to these studies is that :hey were .. -\)nf i:1ed :L) 3 1 imited n:.Jmber I..li :itJn- ,j"rd engin" fuels. Consequ"ntly, th" results ,)b- tained cannot be readily applied to alternative fuels, Dr fuel b]"nds. The present studv was undertaken to remedy this deficiency. Its objec- tive is to provide the sa~e t~pe of information on fuel drop evaporation, but in a more general torm. thereby extending its r;mge of application to 3 fairly wide variety of hydrocarbon fuels. To achieve this ~oal it is necessary to select a correlative fuel "roperty that. will define to a sufficient Jegree Qf accuracy th~ ~v3poration ~flara~teristics 0f any given fuel. It is recog- ni?cd that no single .::he~ical or "hvsical ;>ropL~ ty i:i ~onplet~lv sdtisf~lct0ry ~or tilis purpos~. H0WCV~r,. t:-tc ~lver,l~t? :,oiling ;;01nt 1..)0 perct!nt r~cl)veredJ has ::tuch !:.o commend it, since i.t is directly related to !ucl volatili~y and fuel va- ?or pressure. It also '1;IS the virtue 01 being edSY to ::neasure. and is usuall:: quoted in fuel specifications. For thes(~ reasons the ,H'c-rage boiling poi.nt was chosen for the present study to (!laracteri~~ th~ fuelts ?r0r~nsity for ~vapor.l '(i00 . ilAqC EQt:ATlOSS l'he procedla~s ~:nplvy"'d to Jt:!tt..~rmin~ the variation of the effective evaporation "onstant loIith air pressure, t""'perature. and ,"plvcity, ~uel drop size .. md average boi ling ,)oint, follow closely t~ose outlined in detail in pr.~vious pub- lications (1. 2). Thus 0nly the basic ~quati0ns requireJ for the study are presented below. For further informat ion ,'n the phvs ieal propert ies "t fuels and fuel vapors ... lIld :nethods for est imating reierenc .. values c,f tempt'rature dnd species concentration, reference should be made to these earlier companion papers. According to Faeth (3) the heat transfer coefficient between a fuel drop and a surrounding quiescent gas is given by Nu h D k g 1n( l+B M ) 2--- BM (1) The heat transferred from the gas to the drop is Substituting for h from Eq. (1) into Eq. (2) gives The heat used in vaporizing the fuel is (3) (4) where L is the latent heat of fuel vaporization corresponding to the drop surface temperature, T. We have (1) s ~ T 10 • 38 cr s L = ~ 'T - T- I bn I cr bn I ( 5) L -.J Now the rate of fuel evaporation of a single drop of diameter, D, is given by (4) Substituting for mF from Eq. (6) into Eq. (4) gives ( 6) (7) The heat available for heating up the droplet is obtained as the difference between Q and Q e • From Eqs. (3), {6) and (7) we have (2) (S) where s~, the ~ass t.ansfer number, is given by (1) i p : exp [a-bl (T-=-43) 1 -L s (9) and BT , the heat transfer number, is defined as B - c (T. - Ts)/L T Pg (10) In Eq. (9) P is the ambient pressure, and M is the ratio of the molecular IJeights of fuel and air. Values of a and b for several commercial fuels are listed in Table 1 of reference 2. The rate of change of drop surface tempera- ture, Ts' is given by or, d T ~ L iBT __ So = - 1 dt c m IBM PF L- where m = droplet mass = (~/6)~FD) Also, we have, llly = 2~D(k/cp) In(l + B) b hence dD dt CALCULATION OF HEAT-UP PERIOD (11) ( 12) (13) (15) In or1et to calculate effective values of evaporation constant it is necessary :irst [~ estimate the dur~tion of the heat-up period d~d the drop diameter at the end of the heat-up period, using Eqs. (12) and (I'» r'ospectivel:,. The main drawback to these equations is that their solution entails iterative procedures that tend to be tedious and time-consuming. To sit':!- plify the process an alternative approach has been developed which is much ~horter and forfeits little in terms of accuracy. The basis of the method lies in the deSignation of ~ean Gr er:ec- tive values of : and Is for the heat-up ?eriod which, when inserted into the appropriate eqlla- tions, allow the duration of the heat-up ?eriod and the drop diameter at the end of ~~.is ?eriod to be readily evaluated. The r.lethod has jeen full;' described elsewhere (2), and onlv :he ff!- sulting key equations are ;,resented belew. For the mean, or effective value o! ' ~uring the heat-up period we have Sk hu _.-&.._- inll + B ~ . " :'1. P g • e :1U " 16) r- ~! p . !exp[a-b/(T ---=~3)1 - r Shu 1,17) -1 where B = ~u In order to estimate the heat-up ?'Hiod ::q. (12) is rewritten, using Eqs. (6) and (13). 3S - T S o! ( IS) -------....... -----------------~,------------------------------------------------... --... --------... ------... --... --------... --- where Dttu is the effectivE! mean diameter during the heat-up period. It is related to the initial drop diameter, Do' by the equation 111U (19) (20) It is important: that the physical properties contained in Eqs. (16) ~o (20) should be evalu- ~ted at ~hc correct level of temperature. For c and - F the appropriate temperature is 0.5 PF (T + T ) . For 'F the proper temperature s s 0 st e is T The drop diameter shu at the end of the heat-up period is readily obtained as , 1 D- D- .~thu (21) 1 a 'hu and the drop lifetime is given by (22) , " :.thu + Dj/\t ~23) CONVE(''TI\'E EFFECIS ON Fl.rEL DROP EVAPORATION ~!ostpub1ished values of evaporation con- stant, '. rel~te to steady-state evaporation con- ditions in quiescent :nixtures. A method for es- tima::ing st tor any stipulated values of pres- sure, tempel'ature and fuel properties, is de- scri!Jed in reference 1. This same m.?thod has been used to examine the variation of st with Tbn' The results 3re sho1.'Il in Figs 1 to 4 as grapns "f 'st plotted against Tb for ambient tel!lperatures of 500" 300, 1200. Y600. and 2000K, dt pressure levels of 100, 5(10, 1000, and 2000 ie accomplished by defining an effectlve evaporation constant as (26) where t 1s the total time required to evaporate the fuel drop, iocluding both .::onvective and tran- sient heat-·up effects. From Eqs. ('::1) and (25) iff i , , r I f, i I --_____ p, 500 .po ~ II ~ TtX),>< ----2000 0 :)8 "~ 86 .. r E E J5r-- "," i r 1 Lee C4~ l- s3L I ----------------- ------- ~J I r- --~ ---<;z'C -i I -; ~ ~ 1 , ~~ __ ~ ____ ---L--'--, __ --"- ~ 40(' 4":-C SC C '5·: 00' Fig. lni luene" oi arnoi"nt temperatur" a.'1d normal boil ing temp"ratur" c'n the steady stat" "vaporation constant :or a pressur" c)t JOO;"Pa. we hav" t + hu in whicn Rehu and Rest ar" bas"d un ~\\' and ),;t respectively. (~ot" that u st : J.~5i)1' ';alues of 'eff' calculated irJm Eqs_ \~o) dud \~-) t ,lh:' :-itlown pl,.Htcd in Figs. :; : ... ' :-ht.·:i~ :-:~- ur~s ~epr~s~nt pi0tS ~~ '~;t ~~rsus r~n for varivus \fdlu~s ..::f [-Do 11 ..it three- .l~\"~:'s ,:>ressure. namely lUll, luOO an'; ':vUOkPa, .lr.<.l ::11'.,,: l~vels 0t ambient :.~mperature, ~amtl'ly ;'JO. :"::t)t) aGd ~OOOK. They sho .... that. ~,,!\eneral, "n increases with Ln<:rease in .lmb ient te"'peLit 'He. ?ressur~. vcl()cit~· ..ind Jrop .'5ize • ..ind "!i:!lin ... ~:h':-O ~ith in..:rc.:1.st.1 in :lor:nal ~oilillg tcmp~r..ltt.rc. "The ...: ... "'ncepr. .... "'i ..in ~ficcti .... e \'·d.lu~ ... ,i ~'~'':iP "rat ion constant ~0Ilsi t .,In t ... i t ~l :1<' f::t.:.-il b u ilia ~ ?o in t d t ~\ c' ... ",ni.le:: ~.~1t' l\'era~t:! ~·.J.t\;:, .... \: jett'nnin~J. DV .Ji,v:.J in.'i! ~F f rvCl Eq. ~.:: B J ..is CONCU'S! uoSS ~: f fu~l t!vapo!'ation is frena ::q. \ 13) :,v t" " -' [0 t~~ srrav ~ombu~ti0n oi :iquid hvdro- ~.rbun ~~~l~ th~ heat-up period occupies" signifi~.mt proport i')n oi the total ,hop l1ie- time. In ~onsequ~nce the .)v~rage evaporation .. . ; ..... E E 1,2 1.0 08 06 04 02 022 014 010 Fi!'-. f:>. Variation _,( ,,(fective evaporation ~0nstant with normal Doiling point at a ?ressure of lOOOkPa. rate is lower than the "teady-state value and the drop lifctime i" extended. The eff.'cts ,)! :t,e ~~at-Jr period ~nd thos~ 0f forc~d C0nv~c :il.)n can be .lCCOUlltt!O i"or quitt" ~on\·t:niently :,y defining a mean, or efffec:tive, value oi evaporation constant, eff' such that the ~rop lifetime is obtained as , t ~ cr.' e ,) erf rate of iuel ... hile the .werage evaporation during the drop :i:'ethl<~ i~ giv<'11 t-v --------------------------------------------------------------------------------- ., .; .... E E 2.8r-,-----~--_,,-----r1----,----~r---~----, f>: 2000 k Po UDo ' (m/s)(/L) 2.4 ------.---------------------~ 2.0 1.6 1.2 0.8 1.8 1.4 ,0 0.6 0.2 0.22 0'. ~T •• OOOK O,.~~~ 0~~5 ::~,~~ . 420 440 460 480 500 520 540 560 Tbn, K Fig. I. Variation of eifect::'ve evaporation constant with nonnal boiling point at a pressure of '::OOOkPa. Calculated values of evaporation constant, eorn!sponding to \~ide ranges of fuel t"pt', drop ,;ize and ambient ,~onditions, show that eif :'n- creases With incr,~ase tn pressure, temperature. ~elative velocity, and drop size, and diminishes \lith increase in 110ntal boiling temperature, :-iOMESCl.ATUIU: a, B~ 3T .: p J b ~onstants in Eq, ~9} ~ass diffusion t ransfel' nUUlber thennal diffusion transfer number specif ic h,eat at .::onstant pressure, iration on tlllO fuels. .. "umbersl" parentl~~gnate refNences at end of paper. Nonnan R. Sefer, Job A. Russell, Thom. W. Ryan, III, and Timothy J. Callahan Southwest R~an:h Institute San Antonio, TX REFINERY MODELING STUDIES In the first project phase refinery models were developed in cooperation with Bonner &: ~oore Associates using their Refinery and Petrochemical Modeling System to represent composite refineries. Three regional models were used wi th forecasts of 1995 crude supply and product demand to generate baseline cases. Representative shale oils and coal liquids were added to the data base along with processing schemes for synthetic crudes. BASIS OF STUDY - The year 1995 was selected as the basis for f(,recasts. Shale oil and cOal oil production was expected to ~ substantial by then. Also, fifteen year~. would give time for assumed changes in engine types to have significant effects on the vehicle population. Three regions were selected where syncrudes were expected to have major impact (Fi&ure 1): • Rocky Mount.::ins • Mid-Continent • Great Lakes These regions were definen engine peformance and BTU content of the fuel. These factors were used to adjust the volume of the alternate fuels in the product options cases. The net volume reduction of 7.28% for maximum dies~l fuel is very close to the 7.24% for broadcut fuel. ThiS similarity \vas not planned, but It ~oes allow comparison (llf re·sults for the t~o fu:1 options at ~he same level of product reduction 10 the followmg section. PRODUCT VOLUMES TO REPLACE GASOLlNES, PERCENT OF BASE CASE GASOLINE Maximum Base Diesel Broadcut A. Relative Fuel Economy, MPG 1.00 1.35 1.24 B. Percent Gasoline Replacement, % 0 30.00 40.00 C. Replacement Volume, 96 (B • A) 22.22 32.26 D. Motor Fuel Reduction 96 (8-C) 7.28 7.2/j. Product Volumes - Highway transportation fuels were modified for three series of cases in each region. The ratio of gasoline to total distillate shifted from 0.93-1.36 in the base cases to 0.54-0.73 in the maximum diesel cases. All other products were held constant in each region except that LPG production was allowed to vary. Raw materials then were varie'th 3.92 3.63 m Soth 2.74. 3.07 Average 3.l.5 3.16 The averge raw material savings for fool" cases was alm(>st identical with the reduction in pr(Nuct volum~. The variations above and below this reduction. are a result of differences in processing and energy con~lmption within the refinery. 8roadcut fuel manofacture to replace ~O'l(, of the gasoline also resulted in raw materials savings. The savings in the syncrude cases lIIer~ VOLUME % OF BASI~ RAW MATERIALS BCIF Pr'oduct ~ ~~ Reduction I Shale 3.27 2.97 I Coal 3.59 2.97 II Both 4.28 3.61 III Both 3.52 3.06 Average 3.67 3.15 ~ote that the transportation products were reduced because of improved fuel economy of the broadcut flN~l. Broadcut savings II/ere higher than the fuel reduction becau$e of added benefits in processing and energy consumption in thc~ refinery. Similar savings occurred for broadcut fuel made from petroleum. Gasoline supplements were used at 10% concentration in the Rocky Mountain region. .'v1ethanol replaced slightly less than I barrel of petroleum per barrel of supplement. Eth,anol and MTBE were somewhat mo.re effective and saved over I barrel of petroleum per harrel supplement. Synthetic naphtha from methanol was incorrectly assumed to be used as a gasoline supplement. Later information showei:! that 'v1obil VlTG was a finished gasoline with well balanced lolatdi ty and could be marketed wi thout further blending. The Mobil process is likely to b4~ used in Ilew plants independent of refineries. Refinery energy consumption was aCCOlUnted for in the total raw materials used. Investment costs were includer blends were made at lower cetane levels using 35 and 50 percent concentrations of coal distillate. BROADCUT FUELS - Seven broadcut fuels were patterned after blends with a variety of compositions in the computer study. These wide boiling range prod'ICts were made wi thout octane or cetane specifications, using components in both the gaSOline and diesel fuel boiling ranges. Paraho shale oil naphtha was supplied by SOHIO. Coal-derived naphtha was simulated as described in the section on gaSOline formulation. Diesel boiling range fractior.s from shale, coal, and petroleum were used as needed to match properties of the blends. Since there was no standard broadcut f~1 for comparison, arid testing was done in diesel engines. performance was compared with Phillips D-2 diesel fuel. GASOLINES - Eight gasolines were tested in the project. Two of the~~ fuels were supplied ready to use. Gulf Research and Development Corporation provided a blend of 5 volulll VEHICLE TESTING - Selected fuels were tested in V\!'hicles on ill chassis dynamometer by the Emissions Researc!l O;epartl'M'nt at SwRI. Testing was done in accord with ~ Federal Test Procedure CFTP) ane tests. It is clear however. that optimization based solely on maximum brake torque is not sufficient to define the optimum li~ning due to knocI< limitations. The O{Jtimum timing cO'.!ld lie in a region in which the knodc has a dE'trimental effect. Therefore optimi:zatioo bas>ed on maximum power should be coup.led with a quantita.tive estimate of knock. This estimate could simply be a measurement of the amplitude of p.f'essure oscillation after ignition. Thus the method would allow maximizing power output while remainil't3 out5ide thl!:' region of detrimental knock. Other methods of optimization involve maintaining fixed power output or fixed energy input instead of fixed air-fuel ratio. The fixed power optimization method would involve maintaining a given load while adjusting the injection timing to obtain a minimum energy consumption. While all n1ethods require precise measurement of fuel flow, this method w"tJld require relatively long measurement intervals so that the standard error of r~easurement would be a relatively small portion of the total fuel flow. The f.ixed energy method involves adjusting the timing to obtain maximum power while energy input to the engine is held constant. This method requires that the ene~gy content of the fuel be known accurately. One advantage of this method is that it accounts for differences in energy content. Thus any ;'lcrease or decrease in 'Tlaximum power would essentially be proportional to an increase or decrease in efficiency. Fixed Power Output - In order to illustrate the other methods of optimization, the 1500 RPM and 20: I r'\FR test point was selected as a basis for further timing optimization runs. The fixed power output scheme was run first. Figure 5 is a graph of BSEC versus tim.ing for ~he baseline and broadcut fuels, respectively. These data were obtained by varying the timing while adjusting the fuel flow to maintain rons~af1t loads of 21.2 ft-Ib for the base fuel and 25.7 f~-Ib tor the broadcut fuel. The optimum timing occurred at :he minimum fuel flow, hence minimum BSEC. -\s indicated by the figure, the optimum timings were 200 BT~C and 220 BTOC for Broadcut fuel 6 and Pl-tillips 0-2, res~~tively. These timings were advanced from those obtained by maximizing power output which were 160 and 180 BTOC for the Broadcut fuel and Phillips 0-·2, respectively. .l\t the optimum timings, the energy consumption of the broadcut fuei was 16 percent less than the base fuel. It should be not~ that the load set points for the conS~3nt p,)wer optimization were lower than the loads obtained at the corresponding test point (I500 RPM, 20:1 ,\FR) and optrrnum timings (160 BCF, 180 Base) for :he fixed air fuel ratio optimization. For the broadcut fuel. the 25.7 ft-Ib set point was 6.2 percent lower, ..vhil.e the set point for the base fuel, 21.2 ft-Ib, was 10.9 percent lower One possible explanation attrit-utes a decrease in load for trn:' ,se fuel to increased clearance between injection plunger and barrel due to wear. Therefore, in order to maintain the <;arne fuel flow ratE', the length of the injection I"ve'1: ..vas II1creasE"d. thus compromising the combustion procl'ss .~nd decreasing efficiency. It was suspe-c:ed that the 'Tlarginal lubricity of the heavy naph~ha comprising 50 perc('nt of the broadcut was responsibl~~ for the injectieen necessary to make indicated horsepower measurements. Thus any change in friction horsepower could be calculated by the difference of the brake and indicated measurements. A change in the combustion process could also be detected by a change in the apparent heat release. Fixed Energy Input - The fixed energy input scheme involved matching the ener~:' input of the broadcut to that of the base fuel, thus accounting for differing heats of combustion. The test conditions was 1500 RPM and the load obtained at the 20:1 AFR. The injection timing was then adjusted to find maximum power output. Figure 6 shows the load versus timing curve for the broadcut fuel when the energy input was matched to that of the base fuel during the fixed air- fuel ratio optimization. As indicated by the figure, the optimum timing for the broadcut was 160 BTDC; the same optimum timing obta;ned by the constant air-fuel ratio method. Under the same test c nditions, the optimum timing was 180 BTDC for the base fuel. Although the curves fall close together it should be noted that at the time when the broadcu! fuel test points were run, it is hypothesized that an increase in friction horsepower decreased the brake measurements by 6.2 percent, while the base fuel data were collected before any appreciable wear in the injection pump. Allowing for this difference, the broadcut fuel produced a 6.2 percent increase in power output. As with the fixed air-fuel ratio method, both the fixed energy input method and the fixed load methods of optimization produced results which were affected by the degree of engine knock occurring during the test. ENGINE TESTING RESULTS The following comments summarize all of the major results of engine testing which have been presented in previous reports. (10,11,12,13). Diesel fuels derived from Paraho shale oil were well refined products. Their performance and emissions were similar to the base fuel and the minor differences were explained by differences in boiling range or other properties. Two blends with petroleum fractions indicated that the straight materials were compatible in blends. The SRC-II coal-distillate was a product from the c0<11 liquefaction process and not further refined. It was unstable and had a strong odor. Twe- blends were made· at low SRC-ll concentrations to represent products from Rocky Mountain Case SA and Case 12. Both fuels ran well in the CLR diesel engine with energy consumption close to the base fuel. Particulate emissions were high for both fuels, and hydrocarbon emissions were high for Case SA. Tllese effects. may have been related to high ')10 percent distillation temperatllre ,lnd viSCOSity as well as the presence of SRC-tl. Coal Case 5.1\ was also tested in a 115-hour durability run. Deposits fOlUnd in the combustion chamber were believed to have caused a piston ring ~o stick. This in turn caUS<\XI higher wear rates. Carbon residue of the lubricatinR oil also increased faster than with the base fuel. The same Coal Case 5A diesel fuel exhibited much better performance in the Oldsmobile vehicle tests. Fuel economy and particulates were practically identical with the base fuel. Only nitrogen oxides emissions were high which may be related to hydrocarbon types or organic nitrogen in the fuel. Higher concEntrations of SRC-II were used in Medium Cetane (3:1.4 CN) and Low Cetane (25.4 CN) blends. Further problems were identified in the CLR engine with these two lower cetane number fuels. The :-.1edium Cetane blE~nd caused knock at all speeds and unstable operation at some speed and load conditions. The Low Cetane b.lend caused severe knock, unstable operation, and would not allow cold starting. Particulates and nitrogen oxides emissions were high for both fuels. The Medium Cetane diesel fuel ran suprisingly well in the Oldsmobile vehicle, with no increase in knocking. Fuel economy was down slightly in the city cycle. Particulate:s were less than the base fuel, but all gaseous emissions were higher. Coal-derived diesel fuels were evaluated in blends over a range of properties, and problems were identified above fClr certain blends. The results and fuel properties can provide a basis for estimating the minimum degree ol[ treatment of SRC-II distillate for acceptable performance. Broadcut fuels were tested in the same diesel engines and ran reasonably well without engine modifications. In the CLR engine, fuel consumption was generally more~ than the base fuel and was higher with more naphtha in the blends. Hydrocarbon emissions followed a similar pattern. Particulate elntSSlons were high for blends with high 90'\; distiUation temper'ltures. Knocking was moderate to severe with all fuels. The two lowest cetane fuels would not provide stable operation at all speeds or cold start ability. The Oldsmobile diesel was more fuel tolerant than the CLR for knocking tendency with two fuels. BCF-2 and BCF-4. Fuel economy in MPG was lower than the base fuel and emissions 'of hydrocarbons and carbon monoxide were higher. BCF-4 with higher naphtha content exhibited the lowest combustion efficiency. The only modification required was a booster pump to provide positive suction for the engine fuel pump. A series of tests was run to optimize injection timing for one brOClocut fuel (BCF-6) and the baseline fuel. Injection timing was adjusted in 20 increments to find the point of maximum power output. The tests showed that fuel consumption (in BSEC) was improved for both fuels by timing optimization. The broadcut fuel performance improved more thelln the base fuel, and changed its ranking from "worse than" to "better than" the base fuel. Emissions at optimum timing for -the broadcut fuel were higher NOx. lower CO, and only slightly higher hydrocarbons. Ttte main impact of the test results was that timing or other optimization can substantially if'flproVE' the relative performance of a test fuel. The results of these limited optimization experiments point out the need for standard test rnethods for alternative fuels. The procedures should be developed to give each fuel a fair test, and should not be based on an engine optimized tor petroleum fuels. Two advantages would accrue from such procedures. First, test results from various laboratories would tend to standardize and be more comparable. Second, data needed for future engine design would be provided. Gasolines tested in the CLR spark ignition engine showed only minor variations in performance and emissions from the base fuel or among the eight test fuels. The fuels were made to unleaded regular gasoline specifications and had similar properties, but with differences in composition, !>oth hydrocarbon types and oxgenated compounds. Therefore, any differences were primarily composition effects. This effect showed with the measurable increase in average energy consumption (BSEC) for SCD gasoline. Use of ethanol in the modified SCD blend improved energy consumption; and methanol made a somewhat larger improvement. MTBE in a modified SCD blend did not change energy consumption. Although test results were similar for all gasolines, the SCD gasoline with 6.9 percent methanol appeared to have slightly lower emissions and higher thermal efficiency than the other fuels, and in particular than the similar SCD blend with 10 percent methanol. Additional work may be worthwhile to verify the results and to find reasons for ~he deleterious effects of the additional 3.1 percent methanol. \tobil MTG gasoline showed good performance in all three types of engine testing. In the single cylinder CLR engine, the \tTG emissions were lower than the baseline gasoline. The CLR durability runs resulted in less wear during the :-.1TG test which was consistent with less lubricating oil wear metals, viscosity reduction, and fuel dilution. In the multi-cylinder tests in a Volkswagen Rabbit, the MTG produced 3.6 to 5.5 percent better \tPG and slightly lower emissil.ns. The SCD gasoline gave 4.6 and 6.4 percent be.tter MPG than base fuel in the Volkswagen Rabbit. The SCD blends with 10 percent methanol and 10 percent :-.1TBE had slightly lower fuel economy than base fuel on an MPG basis, but were about equal in miles per M:-.1 BTU. The methanol blend produced higher CO and HC emissions, but lower NOx. The 'ATBE blend emitted more CO than baseline. Emissions from all gasolines would be controlled to 1982 EPA standards by use of catalyst. CONCLUSIONS This report has covered thf- project in condensed form except for the more det.dled description of recent work on optimized fuel injection timing. The following conclusions and recommeondations apply to the overall project. essentially as presented in the project final report. ( • ..:i. REFINING STUDIES - The linear programming ffiOOOls exp.lored maximum diesel fuel. broadcut fuel and oxygenate gasoline blend cases in the Rocky -"ountain, Mid-Continent, and Great Lakes regions. The main conclusions were: l o o o o o o o o O"oduct compositions in provided patterns transportation fuels in phase of the project. the several cases for blending the experimental The amount of raw materials saved or replaced in each case was a measure of economic benefit, since purchase of raw materials is ',he largest refinery operating cost • . \1aximum diesel fuel saved an average 3.2 percent of raw materials, the same amount as the reduction in product demand as a result of better fuel economy for diesel engines. Broadcut fuels cases saved an average 3.7 percent of raw materials, slightly more than the 3.2 percent reduction in product demand because of better engine fuel economy. Refinery energy savings were greater for broadcut fuel than for maximum diesel production. Broadcut fuel production could be increased but diesel fuel was at its limit. Early development of engines !o use broadcut fuel (or any fuel requiring less processing) would avoid building fadlities to make conventional fuels (such as more unleaded gasoline). Oxygenated compounds in gasoline saved raw materials in amounts proportion to the volume of gasoline supplements used, as follows: '-'ethanol Ethanol 'ATBE 0.83 to 0.96 LOI to 1.21 1.16 to 1.19 The original forecasts and mode·ling premises were reviewed and found to be valid, with one exception. The 1.4 percent annual gt"owth rate in product demand projected in 1979 might be replaced by ai><)utO.5 percent annual decline in 1982. Therefore, the original conclusions about investment costs f.or new facilities would change and have been omitted in this discussion. ENGINE TESTING - Results from engine testing provide· a basis for numerous conclusions in thr~ categodes. General Conclusions - Findings with broad applications in the first group are as follows: o Diesel fuels of normal specification quality continued to show good fwel economy and reasonable emissions. Savings in refining raw rNIterials and energy use are available up to some limiting diesel production. o o o o o Diesel fuels of somewhat lower quality can be utilized with penalties in emissions. Potential savings in refining were not evaluated. Paraho shale-derived distillates which were adequately refined performed well in diesel engines. Results with straight DFM and JP-5 and with blends showed only minor differences from petroleum. SRC-II coal-derived distillate at less than 20 volume percent in blends performed well in single-cylinder and vehicle tests. Broadcut fuels blends were evaluated in diesel engines with variable results uepending on properties and composition •. Results were better in a vehicle than in single-cylinder tests. Fuel consumption and HC emissions generally were higher than diesel fuel, and overall performance was better for blends with more than 32 .::etane number. (See the later comment on single-cylinder engine optimization). Gasolines of varying composition showed little variation in the single-cylinder engine tests because of similarity in properties. Problems - Various problems in use of the fuels werl~ identified as follows: o SRC-ll distillate at 16 percent of the blend was tested in a CLR engine durability run. Deposits in the combustion chamber caused a piston ring to stick. Lubricating oil degradation and higher wear were observed. o Blends with 35 and 50 percent SRC-i1 operated poorly in !he CLR engine with high particulates emissions. The 35 percent blend ran well in a multi-cylinder vehide engine, but showed high gaseous emissions. o Broadcut fuel consumption and hydrocarbon emissions were generally higher with both CLR and vehicle engines. The effects were greater in fuels with lower cetane number and higher naphtha content. Potential - PromIsing fuel-engine combinations that were found in the engine phase included: o Broaocut fuels could be used in diesel engines with minor fuel system modification and an increase in HC and CO emissions.. Refining savings are equivalent to those obtainable by making additional cfiesel fuel, and potential ;>reduction levels acehig~. o o o o o o o BroadCU1: fuel performance can be improved by higher cetane number, lower naphtha content, and perhaps other property changes. Effect on product economics is unknown. The limited optimization study with one broadcut: fuel in the CLR engine showed marked improvement in performance and emissions. This approach made the fuel more us,able and offers encouragement for further development. The fixe,d energy input method appears to be m05it advantageous for optimizing injection timing. It accounts for he~ting value differences and allows more direct t:omparison of the fuels than fixed air-fuel ratio and fuel flow. It also allollls shorter tests than fixed power output with measurement of smal! variations in fuel flow. Gulf gasoline with methyl aryl ethers performed well in !imited testing. \1ore extensi1le testing had already been done by Gulf (15) and others. \-Iobil ~,HG gasolin,::' compared favorably with baseline fuel in all three types of engine tests in this study. Three oxygenated apparently compatible derived gasoline and effects. compounds were 'lith simulated coal- caused no adverse Simulat,ed coal-derived gasoline with 6.9 percent methanol appeared to have advantages in engine performance and emissions. RECO\1MENDA TlONS The results and conclusions presented led to the following recommendations: I. Coal-d€1'ived distillate or synthetic crude evaluation should be based on an adequa~:ely treated diesel fraction. The processing would probably be hydrogE'nation at two or more levels of severitJr. Data for evaluation, of ;T'anufacturing and enough fuel for engtne and vehicle testing should be provided. 2. Broadcut fuel quality variation should be ex.plored to develop specifications more SUited to needs of actual engines and fuel Joll 3. 4. 5. 6. 7. systems. This step would be related to the following three proposals. Broadcut fuels optimization studies in diesel engines could explore performance aod emissions under !est condi~ions best suited to the fuel. Systematic variation of fuel properties would permit generalized conclusions. Minor engine modifications could also be considered. Other types of engines should be used to explore use of broadcut fuel from petroleum or synthetic sources to establish desired quality parameters. Candidate engines could include Stirling, turbine, stratified charge, spark-assisted diesel, or diesel engines with other combustion chamber designs. With modified speCifications from reccmmeodations 2 through 4 above, refinery models could be used to evaluate the eeect of the new quality levels. Shale-derived and coal-derived gasoline components should be obtained or prepared to ~e blends for engine and ver'cle testing. The most likely components would be reformate and catalytically cracked gasoline. }\. standard test procedure should be developed for evallJating alternative fuels. The Jlf"ocedure would define methods to optimize spark advance for SI engines or injection timing for cr engines for the include severity of engine knock, heat relc'ase rate, indicated power, and possibly wear of engine and components. .'\CKNOWLEDl.R. Sefer, "Identification and Evaluation of Optimiz,ed Alternative Fuels," Status Report and Pl'ojecIC Outline for Automotive Technology Development Contrdctors Coordination \1eeting (ATD CCM), October 23-25, 1979. 342 9. N.R. Sefer, "Alternative Highway Fuels from Shale and Coal Syncrudes," Status Report for ATDCCM, November 11-14,1980. 10. N.R.. Sefer, and J.A. Russell, "Formulation and Evaluation of Highway Transportation Fuels From Shale and Coal Oils," Report No. DOE/CS- ~OOI.7-2. December 1981, (Second Annual Report). II. N.R. Sefer, "Formulation and Evaluation of Fuels from Shale and Coal Oils, .. Status Report for ATD CCM, October 26-29, 1981. 12. N.R. Sefer, J.A. Russell, T.W. Ryan, III, and T.J. Callahan, "Refining Studies and Engine Testing of Alternative Highway Transportation Fuels," Report ~o. DOE/CS/5GOI7-3, September 1982. (Final Project Report). 13. N.R. Sefer, "Engine and Vehicle Testing of A1tl~rnative Gasolines," Status Report for ATO CCM, April 14, 1982. 14. E.T. Robinson, "~efining of Paraho Shale Oil Into Military Specification Fuels," Twelfth Oil Shale Symposium, Colorado School of \lines •. l\pril 1979. 15. G.M. Singerman, "Methvl Aryl Ethers From Coal Liquids as Gasoline Extenders and Octane Improvers," SAE Paper 810443, SAE Special Publication SP-480, Alternatt> Fuels. February 1981. 16. G. Tan, and A.J. deRosset, "Hydrot .. eating and Reforming H-Coal Process Derived Naphthas ... UOP, Inc., DOE Report No. FE-2566-12. \1arch 1978. 17. "Identification of Emissions From Casolmes Del"ived From Coal and Oil Shale." EP/\ Contract No. 68-03-2377 (in progress at SwRl1. Project Officer: Robert J. Garbe. EPA. Ann-\rbor. \1ichigan. P,-oiect Leader: Lawrel')Cf.· R" Sml tho SwR!. San Antonio. Texas. APPENDIX Table 1. Summary of Emissions ;l!'ld Fuel Economy Tests in a 1981 Oldsmobile Cutlass with a Diesel Engine Federal Test Procedure (FTP) HighwaI F~l EconomI Test (HFETI Fuel F';el Emission l gm/mile Econ. Emission. gm/mile_ Econ. Fuel HC CO NOx Part. \fPC" HC CO NOx Part. \1PG Baseline D-2 0.26 1.14 1.05 0.383 22.44 0.15 0.71 ::1.60 0.216 33.6:; BCF-2 ').58 2.17 1.00 0.220 18.55 0.34 1.24 0.55 0.121 28.34 BCF-4 ').53 I.SO 0.S5 0.389 20.94 0.27 1.01 0.50 0.177 30.27 Coal Case 5A 0.18 1.06 1.27 0.389 22.38 0.10 0.64 0.72 0.204 33.22 SRC-ll "1ed. Cetane ').37 1.37 1.61 'J.359 21.66 'J.19 ').84 :1.95 'J.19~ 33.22 1981 Fed. Standard~ ::1.41 3.4 i.O 0.60 Table 2. Sum.nary vf Emissions and Fuel Economy Tests in a 1981 VW Rabbit with 51 Engine and Without a Catalyst Federal Test Procedure (FTP) -------- Fuel Fuel Baseline \1obil MTG Sim. Coal Der:ved seD. 10% \1t'thancl SCD .. 10% MTBE 1982 Fe-:i. Standards Emlsslon l gm/mile_ Econ~ HC CO "lOx '1PG 1.16 8.56 1.09 8.24 1.13 8.37 !.21 9.91 1.16 9.16 a.41 3.4 4.92 24.45 4.39 25.32 4.78 25.57 4.52 23.33 ~.83 23.64 1.0 Highway Fuel Economy Test (HFETl Fuel Eml~!on. gm/ml!~~conomv HC CO ~OX \1PG 'J.92 8.03 5.44 1).84 7.72 4.75 'J.85 8.24 5.26 1.:)0 12.6(, 5.21 'J.92 8.59 5.21 31.28 32.99 33.~'" 29.81 31.15 :-.IOTE:Results in Tables I and 2 are 3Vetaltes of duplicate t. ~. ~ ~,~-~ 22. ~. rhilllp~ fl-: 21. t. 221. ...........J.......4-_L ____ -...l'~ •• ...-..JI'__ ..... _.1.-...-....l-_____ .1 t. -L-! I .--J IS. B. 10. 12. 1-4. 115. 161. 2m. 22. 24. 26. 2e. TI .... ING (OOTQC> Figure 2. Load v ... Injection Timing for 1 ~OO RPM am:! 20:1 Air-Fuel Ratio 1 ~lI'J'~"'. r " 1111l1'J'SI2J. +-Il I L I l ~ I 121D1!UIJ. II , L ::J ~ II 110115111. ;.. v U iii II 111111112118. ~ II SGlII!JIII. ~ flll2lllll2l.t ID. 1. ~ \ \ \ \ \ \ ~ \ POWER :J Philllips 0-2 Optimum .:. &CF (, Optimum x Phillips 0·2 Sl&ndud • 8CF" SUlIldard Figure 3. BSEC vs. Power at 1500 RP'A, Optimum and <;tandarrl !nie<:tlon T:rJ'Hngs for Phillips D-2 and BCF-6 " tr I 1 Q. I III "- :J "- ill v u ~ Ul Ql 14111100. ,. 132100. ~ 12~l1i'l0. _ 11121130. _ 101211210. _ 9(100. _ = Phillip' D·2 0pumum _: 8CF 6 ;)pumum , f'ruillps 0·2 at BCF .. Optunum T"ru~ • • bCF 6 AtP'UU,ps D·2 0pllmurn T,m,"lC' 8111100, L-~ __ .:.._~ ___ . ___ ~. ____ . _ ._. __ ._.~ __ ~ __ ~ __ . ~ ___________ ~ ..... __ . ___ _ 0. 1. 2. 3. 4. 5. 5. B. 9. POWER <8HP) F:Rur~'~' \\"EC V$. Power ~t 1 ~O() RP" for Phillips D-2 and BCF-6 at ,-'pll,.num In,e<:!1Otl Timings of Both Fut'\s " It I :l ID l- in :j ~ 11 n 1 1 "011"_ : l"eJ""-i- I!J 11212""_ r: , ge",,_ g"'Ql"- Q 121121 Ql_ - 25 .. _ 20. _ A A '3- , , ~ 0 , I 'lpt,_ ")hlll :'P$ [1-': rNJECTION TI"'ING f'SEC V~. Inwcllon Timing al Fixed Load (151)0 RP\!\ ;?! : n~l.'"I: 30· .. ~ ! / " / ._. _________ ...... __ ~ __ ~ ___ . _______ ..... _ ...... ___ ...... _~ _____ .......... _4_---..-----4.. ___ .. ----' ~; " '\I 'II 11 " ,. Figure 6, Load v<;. InJectlon Tirnmg at Fixed Energy Input (J 500 RP\l) ALTERNATIVE fUELS II SESSION Sumnlary: Report of Hydrogen 51 Engine Research Thp objective of the proJ~ct reflected in this paper 1S to document an ~xperimental design data-base on hydrogen-fueled automotive engines. The effort, sponsored b~ the ;).5.-- Department :Jf !':r~E'rgy, :$ Ji[e'-.:~·?d towa:.-d ?Oss~~lo-:, :-:.;.t'.J('.?' cesigns :)t airbreathing ?Iston engj~es ~sing hydrogpn. ~o this end, pertinent performance and emissions (~Ox only) characteristIcs of 19 engine configurations are presented. ConfIguratIonal variations of a 1600 cc automotive test engine included: t~rattled and unthrottled operation i i.e., quantIty and qualIty pov;er level '::o:1trol); central manifold, port, direct cylinder injection; si:1g:e and dIvided combustion :nambers; exhaust ~as recircuLnl'.)n 'SGR). water indl.,:ction and air In~ec':lon; and certain other features. Compar:sons of these hydrogen- engine characterIstics wIth the stock gasoline-~ueled reference case are made at the same displacements,and at J. 'stoc<.,' compression ratIo::>f 9.0:1. PROSPECTS rtND PROBLEt4S of ~~ydrogen fueled inter~al combustion engines have been feviewE'd in the past few years (1,2)*. As a consequence of interest and activities in hydrogen as a candidate allter:1dtlvc fuel ::leg inning about 1970, t~e absenc a of a comprehensive engine design data-base became apparent. The 4-ye~r proJPct reflected in the present summary paper ~as establlsr.ed in 1976 to prOVIde an initial contribution to such a data- base in order to provlde technical Robert R. Adt. Jr. and Michael R. Swain Unlv. ot Mia",! John M. Pappas Hawthorne Research and Testlnq tnc 9uidance in possible future engine design involving hydrogen fuel. The project was carried out by the University of Miami's Department of Mechanical Engineering under Contract E(04-3)-1212 with the U.S. Department of Energy (DOE). Hawthorne Research & Testing, Inc., conducted Lhe experimental activities in the University's facilities under subcontract. Escher: Foster Technology Associates, Inc. (E:F) technically monitored the project and assisted the project via supporting liaison (also 'Jnder DOE contract). Comprehensive documentation for the project is available in its annual and final reports (3-5). The basic ObJective was to determine engine performance and emissions characteristics, as well as to explore, and where feasible to investigate, the 'Jnique problems associated with hydrogen-fueled engines. These were known to be. speaking generally: low specific power and induction manifold backfiring (naturally aspirated). rough or abnormal cOillbustion and high oxides of nitrogen (NOx) emissions at high loads, and complex interfacing wit~ the fuel containment system (particularly met.al hydrides). On the other hand, the project was to E'xplore and to capitalize on the unique features of tydgrogen operation, e.g., very wide fuel/air operating range including the ·ultralean" range, l&cK of hydrocarbon (He) and carbon monoxide (CO) emissions and ability to operate at high compreSSion ratios.** *~umbers in parentheses designate References at end of paper. **Not reported hereln; a fixed compression ratio of 9.Q:1 ..,as ;.Ised. Altho~gh the thrust of the project was; directed toward the automotive powerplant field now served by gasoline and light-duty diesel engines, the results are also applicable to both smaller and higher- power engine designs. PROJECT TECHNICAL APPROACH BASIC CLASSES OF ENGINES CONSIDERED "- Two basic classes of hydrogen-fueled piston engines are considered: (1) engines in which hydrogen is admitted into the cylinder prior to Intake Valve Closure (referred-to as Pre-lYe engines) and (2) engines in which hydrogen is admitted follwing intake valve closure (Post-IVC e"ngines). Airbreathing operation alOd ambient-temperature gaseous hydrogen was employed throughout the project. ~~:"!.YS: En9J.~ - These eng ines are slmllar to conventional gasoli.ne- fueled engines in that both hydrogen and air are introduced into the cylinder dUring the intake stroke. 'fhey can be introduced as a mixture, the mixture being fortned by a carburetor-like device (a gas-mixer), or they can be indroduced separately, as in a fuel-injection gasoline engine, with the hydrogen being injected (induc"~d) in the intake 350 manifold or in the vicinity of the intake valve. The injection can be continuous or timed, the latter being used exclusively in this project. With the Pre-IVe engines, sparkplug ignitio~ is used. In addition to using the conventional throttle to control charge density, Pre-IVC engines can be operated with the load being controlled by changing the fuel/air ratio. This method of operation, termed the unthrottled or quality-controlled mode of operat ion, is made possible by the high flame speed of hydrogen over 3 wide range of (uel/air ratio. Po~t-IVC Engines - These engl::es arp similar to compression-ignition engines, but some positive source of controlled combustion initiation is needed, such as a spark-plug (Single or multiple spark discharge) or a glow plug. Gaseous hydrogen is injected directly into the cylinder, ~ow~er.c:r.~ during or near the end of the compression stroke and continuing on into the expansion stroke. Mechanical, electrical and hydraulic pulse-actuated hydrogen injectors have been used. ENGINE CONFIGURATIONS - "!'able 1 delineates the 19 engines to be covered in this paper. The various test engine configurations are grouped first, as follow: (1) type of combustion cha~ber design (open or pre-chamber), (2) method of mixture formation (direct injection Post IVC, gas-mixer Pre IVC, part admission Pre IVC), (3) air-flow induction control (if any), and (4) use of additional mixture components (EGR, water, air injection). In dealing with the design basis for Engines 1 through 19, Table 1 is basically self - explanatory. However, it is helpful to further break down the Table by "natural groups" as follows: ~ine Configurations Nos. 1-3 - The flrst three engines are best described together as being quite equivalent to conventional throttled, carburetted gasoline engines. A single air-throttled central gas-mixer of the conventional "propane carburetor type" provided the hydrogen- air mixture to four-cylinder of the test engine via a stock intake manifold. Single, open, spark-ignited combustion chambers were operated at approximately stoichiometric conditions over the throttled- controlled load range, at commensurate levels of manifold vacuum (i.e., quantity control). Whereas Engine Configuration No.1 is just as described, No. 2 adds Exhaust Gas Recirculation (EGR amounts to be specified) and No. 3 adds water induction. For the latter, several admission techniques were explored with a simple single-orifice injector in each intake port continuously directing water into the valve pocket, intake manifold and/or combustion chamber being selected for the data runs. Typically, the average water/hydrogen mass-flow ratio was about 5. Th'= effect of varying this D?:ameter is brought out in the Project repor ts (3-5). Water lnducrion in hydrogen engines is a rather widely practiced means of both (1) ameliorating the ir.take manifold backfiring problem and (2) suppressing the production of NO x ' F.n'Llne confi2.uration ~os. 4-6 .. In a-·s [iiiTlarsequence with regard to the inclusion of EGR and water induction, this series of test engine configuaratlons again used a single,central gas-mixer feeding four stock combustion chambers. However, air-throttling was not used, i.e., the throttled plate remained 1n the wide- open position. Load control was accomplished by varying the fuel/air mixture, often referred to as quality governing, quality control, etc. 351 This mode of control is, of course, basically similar to that of a typical diesel engine in that, although fuel quantity varies, manifold vacuum does not for a given load and speed. However, for a conventional homogeneous fuel/air charge Otto-cycle engine, it is only feaSible because of hydrogen's uniquely wide flammability limits, due in turn to its exceptionally high flame speed. (the order of 4-times hydrocarbon fuels at stoichiometric conditions, see "Some Theoretical Considerations of Hydrogen as an Internal Combustion Engine Fuel," Appendix 0 (1).) In this project, engines thus ::>perated in the unthrottled mode ranged in operation fuel/air equivalence ratio (PHI) from 1.0 (stoichiometric) down to as low as 0.20 ("ultraleanM ). But, as will be seen (Engine Configuration No. 16), some air throttling at the extreme lean-end was found beneficial. Engine Configuration No.4, analagous to No.1, employed neither EGR nor water injection; No. 5 used EGR and No. 6, water. ~n'il.lne confiluratio~s Nos. 7:9 - This sequence 0 4-cyllnder engIne types all used timed-port fuel induction, rather than the central gas- mixer approach employed in the previously described ~~gines. An individual sleeve-valve arrangement for admitting flow-controlled hydrogen fuel was integrated with each intake v3lve. This fixed-geometry set-up beginning 45 degrees after TDC and ending 135 degrees after TDC in the intake stroke. Hydrogen flow was thereby started after, and terminated before the initiation and termination of air flow into the cylinder, respectively. Engine Configuraton No.7, again analogous to previously described Nos. I and 4, had nei:her EGR nor water induction. No. 8 had EGR and No.9, water induction. All three (Nos. 7-9) were operelted in the unthrottled mode like Nos. 4-6. Ei9ine confi'l~ration ~o. 10 - ~o . ·10 emp oyea-asp.eclal t:iilthrof"tred /throttled mode NOx-control operating strategy. It was unthrottled in the low-load I:ange up to a PHI where NOx generation began its typical steep rise, on the order of 0.7 or thereabouts for the test engine series. At that poi!\t, step-function air- throttling was initiated and fuel-flow commensurately increased to match the unthrottled load. Operation was then sufficientely rich (PHI was on the order of 1.2) such that NOx emissions were again low. Thus Engine No. 10, labeled the "discontinuity engine" was so operated as to enable a step across the characteristic PHI vs NOx peak from a given low level on the ascending slope to an eq~ivalent level on the descending slope (going from lean to rich). As will be seen, there is a penalty in fuel economy (related here as Brake Thermal Efficiency) for this approach for achieving low NOx operation without EGR or water. Engine Confi~uration No. 11 - This configuratlon tested the effect of air injection into the intake manifold runners of a central gas- mixer 4-cylinder test engine operating in an unthrottled mode without EGR or water induction. (In effect, No.4 with the air injection feature.) The objective here was to determine the contribution of forced-air induced mixture turbulence on backfire alleviatiofl, if any. Ef~in~ configuratio~ No. 12-16 - The lnal set of 5 englne configurations were alike in that they utilized a single-cylinder version of the basic stock 4-cylinder design. The leading (front) cylinder remained active and the remaining pistons and valve operating-components were removed. The crank-shaft was equipped with compensating weights and an increased moment-oE-inertia flywheel replaced the stock item. Testing was at a constant (rpm i.e., the 1800 rpm condition reported on in this paper). These configurations each used a single, smaller gas-mixer mounted close-coupled to the intake port. (The previously ~sed central gas-mixer with the unused 3 cylinders' intakes blanked-off was initially tested as well.) In an actual mul.ti-cylinder engine, based on the sel.ected configuration,each individual cylinder would be fueled and controlled by its ~wn close-mounted gas-mixer~ Engine Configurations So. 12-15 were operated unthrottled (quality governed), differing only in combustion chamber design. No. 12 used the !ltock open-chamber hemispheri.cal aesign; Nos.13, 14 and 15 used pre-chamber deSigns of varying geometry cIS supplied by the engine manufacturer (R • D hardware). The pre-chamb,~r geometr ies \Jar ied as iol10Iols.: Eng. Config. No. Portion of '!'otal Clearance Volume 15% 15% 9% Pre-Chamber Volume-to-Orifice Area Ratio 10:1 6.5:1 6.5:1 Engine Configuration No. 16 - used the open chamber and principally unthrottled operation. At light-load conditions, air-throttling was initiated to improve thermal efficiency. ~ine Configuration No. 17 - used an open chamber and unthrottled operation. Hydrogen was injected during the compression stroke and ignited by a multiple spark ignition system. Four different injection timings and lifts were investigated. Engine Confi~uration No. 18 - was ident~11 to Conflguration No. 17 except at light-load conditions, air throttling was initiated to improve thermal efficiency. Engine Configuration No. 19 - emplOyed direct injection of the hydrogen into the combustion chamber near top dead center. Ignit~on was accomplished with a platinum wire glow plug. PREPARATION OF DATA In an effort to present the considerable amount of data in a compact form the following methods for comparison were used. An attempt was made to make comparisons at engine speeds and loads typical of the EPA. city {CVS) driving cycle. PEAK ?OWER - Comparisons of power output were made at 1800 r.p.m. The comparable gasoline fueled engine with EGR and stoichoimetric ai.r-fuel ratio was assumed to produce 113 bmep. FUEL CONSUMPTION - Comparisons of fuel consumption were made on a BTU per mile basis. Three mini mapping points characteristic of the speeds and :oads e~counted over the city· driving cycle were chosen at the suggestion ot Carl Kukkonen of Ford ~otor Company. They were 1000 r.p.m. at 15 psi. broep for .49 Hp-Hr, 1250 r.p.m. at 37 psi. brnep for 1.35 Hp-Hr. and 170~ r.p.m. at 75 psi. ol1lep for 2.16 Hp-Hr. The t~1ree :mints 'tiere wighted by their respoec:tive number of horsepower-hours. The entire 7.5 mile course required the equivalent of 3 horse power-hours to navigate. EMISSIONS - Comparisons of emissions (NO x ) were made on a grams per mile basis. The same three data points as were used to make fuel consumption calculations were used for oxides of nitrogen. The base line gasoline engine was assumed to produce .48 grams per mile oxides of nitrogen. PRESENTATION OF DATA Table 2 shows the results of the aforementioned comparisons. Peak power is presented as a percentage of the gasoli ne fueled eng ine value. Fuel consumption is presented as a percentage of the gasoline fueled engine (greater than 100%, indicating poorer fuel economy). Total oxides of nitrogen are presented as a percentage of the gasoline fueled engine (greater than 100% indicating higher emis~10n levels) . SUMMARY OF TECHNICAL RESULTS PERFOt-IANCE AND DES IGN Pre IVC Engines - (1) Unburned hydroijen was found in the exhaust during normal operation. During richer operation (0.8 < PHI < 1.2), the unburned hydrogen in the exhaust can be ac60unted for by dissociation and a slow down of oxidation reactions during the expansion stroke. During operation at 0.4 <: PHI < 0.8, the unburned hydrogen may be accounted for by: (1) wall quenching of the flame; (2) preferential flow of hydrogen during blowby; (3) small-scale nonhomogeneity in the combustion chamber. During operation at 0.2 < PHI < 0.4, it can be accounted for by bulk quenching. {21 Consistent with the results of others, the unthrottled engine, vis-a- vis the throttled engine, exhibited higher brake thermal efficiency, except at light loads where some throttling is beneficial. (3) Peak power output calculations show that the potential, nonflashback- limited power output of Pre IVC engines can be larger than had been previously reported if advantage is taken of the properties ot hydrogen as a fuel. Test results with Engine 12 where a peak power bmep of 100 psi was found compared to the 115 psi value attainable with a gasoline engine supports the results suggested by these calculations. (4) Except for Engine Configuration No.7, 10, ::'2 and 16, under ideal conditions (i.e., with limited deposits in the combustion chamber), power was limited by flashback for all engine configurations tested without EGR and water injection. ----------------+--------------------------, "...!. . . ....... . - .. _ ... .:.\. ~--.--------.. ----.--~------------.---------. 353 The use of EGR ~nd water injection, ~owever, allowed for wide-open throttled operation at near peak-power PHI (for the levels of EGR and water injection used). (5) Comparison of the results of the present study with those performed by the authors in the past indicates that charge stratification can increase or reduce the lean limit of operation for the unthrottled engine. (6) Proper carburetor (gas-mixer) selection can reduce cylinder-to- cylinder variation in fuel-air ratio with subsequent improvement in performance. (7 Jl For res idence times in normal operating engines, the diffusion rate of hydrogen is not sufficiently high to make homogeneous mixtures from initialJly heterogeneous mixtures. (8) Two independent methods were used to generate indicated quantities from brake measurement: (a) performance map method; (b) Bishop/Taylor method. The methods gave results consistent with each other when applied to the present- study data. The Bishop/Taylor method 'Nas used to make the compar ison of the present-study data with those of others, and good agreement was found, eliminating much of the apparent conflicl: of results as reported by others. (9) The lithium-filled exhaust valves did not attain their performance potential, a result recently found by industry. (10) By choosing the proper displacement, it should be possible to design an unthrottled Pre IVC hydrogen engine with somp ~hrottling at light loads that can operate over a driving cycle with ~erformance and energy conversion efficiency (BTU/mile) equal to that c~ a gasoline-fueled engine and emission levels below the 0.4 gm/mi level. (11) The BTE of the dual-chamber Pre IVC engine is about the same as that of the single-chamber design at light loads. At high loads, as a result of heat loss, the dual-chamber engine yields a lower 8TE. PO!~~~C Engines ~ (1) The B. for the Post IVC engine~ is not as strong .'l function of PHI· as was found '-Jith th,~ Pre IVC engines; the B'l'E for the Post engines was found to be more a function of injector valve design, lift and fuel pressure. (2) The Post rvc eng ine could be throttl,ed at light loads to increase the BTE there. This increase is 3M suspected of being due to better fuel penetration and mixing at the throttled condition. (3) The peak power output for Post IVC Engines 17 and 18 was higher than that of the corrersponding gasoline engine. However, it was necessary to operate these engines with an unacceptably-low coolant temperature. Engine 19 yielded approximately the same peak power output as the corresponding gasoline engine with normal coolant temperature. It i3 suspect~d that the burn-after-injection Post rvc engine can be made to operate with even higher peak power if the fuel injector design can be optimized. ?LASHBACK - (1) Hot spot-induced flashback was found to be predictable and therefore, subject to characterization. There is a period preceding hot spot-induced flashback (Period PHIF) during which the charge is ignited by the hot spot at pro~ressively earlier crank angles until it occurs prior to closing of the intake valve, resulting in flashback. During the Period PHIF, NOx emissions rise very rapidly and the RPM drops. (2) Decreased valve overlap was not found to decrease flashback tendencies negating the hypothesis that flashback was being caused by communication of the fresh charge with still-burning exhaust gases during the valve overlap period, when employi~g common valve overlaps. (3) Lean mixture operation can cause flashback, raising the lower engine speed limit of the carburetted (uniform-charge) unthrottled engine. (4) Evidence was found to substantiate the hypothesis that oil in the residual gas can cause flashback. (5) Partial ignition failure (misfire, flame initiation failure) does not result in flashback. (6) Hydrogen/air induction methods influence, somewhat, flashback limits. (7) Flashback-free operation does not seem possible without EGR or water injection wi th stock water--jacketed cylinder heads operating at ~tock water temperature unless extreme care is taken to continuously clean the combustion chamb~r. Changes in cylinder head coolant passage deSign, however, can defInitely improve this situcltion. (8) Prop<.,- ~ylinder head COolant passageway des.qn is a necessity for flashback-free operation. (9) Throttling of the homogeneous- charge Pre IVC engine with the concomitant mixture enrichment helps to eliminate flashback at light loads. OXIDES OF NITROGEN EMISSIONS Pre IVe: Engines - (1) Consistent with the retiults of others, NO x emissions were fo~nd to be a strong function of PHI. (2) The use of EGR while maintaining constant load,constant eng ine speed and BESA did not affect NO x emissions for the unthrottled engine as a ~esult of reduced air flow with increasing EGR rates. (3) The use of EGR while maintaning constant load, contant engine speed and BESA resulted in a decrease in NO x emissions for the throttled engine operated at constant PHI = 1.0. (4) The use of water injection while maintaining constant load, constant engine speed and BESA was found to decrease the initially low NOx emission level at low PHI. (5) The Jse of water inj~ction while maintaning constant load, constant engine speed and BESA was found to decrease the NO x emission level of the throttled engine operated at PHI = 1. 0. (6) For the same diluent heat capacity flowrate, EGR and water injection were found to decrease NOx emissions by a similar amount. (7) For practical operating conditions. a given volume of air has essentially the same effectiveness in reducing NO x emissions as an equal volume of exhaust gdS. (8) An ~nthrottled engine designed to give good performance over a driving cycle (Federal Register Vol. 35. ~o. 136) gives off NO x emissions well below 0.4 g/mi without using EGR or water in-Iect ion. (9) NO;. ?ossibly a worse polL.ltant t~lan ~O, is founlace. But should the temperature of the glow plug ~corne high enough to produce the first sign of preignition, then the engine would rattle and bounce for a number of crankcase rotati ons until we eventually reduced the supply of ~drogen. It occurred to me at the time that tt:ere are two things that are causing preignition in the hydrogen engi ne. You must supply a hot spot, and we had gone to a lot of work to reduce this hot spot enough to where we could get 100 BM[P out of the engine. But additionally, you need the leftover radicals from the previous cycle. They can exist as we have seen in quite high concentrations. In the case of lean operation, we had 1,000 PPM hydrogen peroxide. So this would mean there are two I14dyS to approach the ;>roblern of reducing preignition. One way would be to alleviate .ill the hot spots. The second way would be to prav; de s~ method of superi 01- sC.ivenging of the c~nbustion chamber to get the residllal s left oller from the previous cycle out of the cc~ustion chamber. Gaseous Fuel Safety Assessment Status Report A5S TRACT :he ~os .;! amos ~at iona I Labor'atory, in support OT stela H~S sponsoreo by the Utt ice ot ~ehicle anO Engine ~ dnd D in the US Department of Energy, has l,noertaken a safety assessment of seledeo gaseous fuels for use in light-duty automotive tr'ar;sportation vehicit's. The purpose 1 S ,0 ;Jut into perspec t i ve the hazards of tnese fuels relatlve to present oay tuels ana delineate criteria tor their safe handling. F~eis ineiuoe compressea ana liquefleo natural gas (diG and 1,/'jG), liquefied petroleum gas (~PG), ana ror I"eter'ence, gasoline and diesel. Thi s paper is a program status report. To ,Jate, phjSl(ocnemical property aata and general petroleum ana transpor'tation information were cJmpileo; ~asic nazaros defineo; alternative '~els ~ere safety-ranked baseO on technical ",'open les J lone; satety oata and vehic Ie ace ioent stat i st ics reviewed; and aec ident SCenarlJS selecteu for turther analysis. -"etncooiogy tur suen analysis is presently ~rl~~r (JnS1J~rJtlon. '"t "Sc. Jf AL TERNAT I'iE AUTOMUTIVE FUELS other t~an :nose aeriveo primarlly from petroleum .ere conSl0ereu for many years and in fact were ~SeU In rel~tlvely minor quantities. More --<:,r~t-j '-eUndling ut :nterest In tile ~~::Il.l:1CIl Jt tnest: fuels nas emergeu. TIle :c'pet", f'Jr tnis is oerived from a variety of reasons lnc!~oin9: V a :ndndate to reduce e;<.haust Dollut ien J eS~jlatlng ruel ~osts o ~0neern uver potentiJI petroleum s~PP:j reauctlon v J JeSl'-e hr' self-sufficiency l import '-"\.Juc t 1 ('11 v potentIal tecnnlcal advantages. T'le ;ilterncHlve fuels -.lnder· consideration are ~y .,0 :neans ne-.. 'O'n.;rgy sour'ees. However, M. C. Krupka, F, J. Edeskuty, J, R. Battlit, and K. O. Williamson, Jr. Los Alamos National Laboratory Los Alamos, NM oecause their use in the automotive transportation sector is limited, an extenslVe cOIIvoercial infrastructure such as exists for petroleum ana its retined prOducts has not been developed. The expec ted inc rea sed usage of these fuels for routine automotive transportation has also eliclteo an inc'-ease in concern over thelr relative safety. "degree of riSK is al"ays dssociatea with tne use of energy sources. Acceptance of large scale usage of new energy sources and technologies by both government dna the pub 1 ic-at-l arge can be exped ited if it can be demonstrated througn aoequate assessment, safety testing, ana operational experience that the intrinsic risk is either equlvalent to or less than that associated with the energy source presently used. Liquld petroleum proouets such as gaso line and naphtha are fla/rlllable, in selecteo situations explosive, yet are safe and acceptab 1 e wnen hana lea properly. The Uniteo States Depar-tment vi i::nerg,Y \DOE) has alreaoy estaollsnec an Alternative Fuels Utilization Program (AFUP). To imple- ment selecteo tacets of tne ~etnane Transportation Research, Development, and Jernonstration Act ot 1980, P. L. 96-512, some fund i n9 from AfUP was a i vcrtea and a Gaseous Fuel program 4ith primary emphasis on methane \natural gas) was oeveloped. Tne progr'am is :nan aged by the Office ot Venlcle ana Engine R and D (VEAD). In support of VERO, the Los AlaJllos National Labor,Hory is unGertaking a safety assessment of selecteo gaseous fuels for use in light-duty automot i ve trans~ortat ion vetlic les. Tne purpose ot the assesslII€nt I s to put into pe,'spect ive the relat ive hazar"ds or tnese fuels compared to gasolHle and oiesel fuels and to deli'leate cnteria for thelr sate hanoi ing in the transportation sector. This paper represents a status report. Completed efforts are described herein but signlticant analysis remains to be accompliShed. TRANSPORTATION )ECTOR In 1980, th~~ transportdt Ion 5ec tor consumeo approx lmate Iy :;0:1. ot the totd i .) ;..etro leum use. Of this Quantity, approximately SOl .. as usea tor nighway motor tuels ;ij.* Motor rur] consumption amountea to about 1.2 " 10 I gallons (gal) \gasol1ne, Jlesel. dna ~;)G~, Gasoline alone ,Kcountea for about :.J ;JII gal (2). ~PG SOld for Internal :Jmb4,Stlon engine use amountea to dOOut 5.0 :0" gal although not all was Jsed for ~OOI Ie transport3- tion purposes (3). On-nlghway tr~nsp0r[!tI0r use of distillate fuel ·J;l ,Jlesei, ,mountea :0 about 1.4 x 10 10 gal (3). ~ne Juantltj)t natural gas used as a motor tuel ~as ~ery ~lnJr relative to t.. 'se Quant;1ies.** ')f the 1.2 x 10' _Gal cf motor -.;el consumed, about S. u " 10 itT qa; .. ere ~sea "OJ personal passe?8er ,enlC les 'dIll] :tlotorcyc :e5, aoout ~.o ,10 gal .,ere usetJ "Jf [''',(,S .1': gross ~ehicle "eiQht \gVWj clds~es ~ dnd approx- Imately 0.1 x '1010 gal 'Jj "Juses ' . .l. .JIS- cussion of resource avai labi 1 itl dna tne imPdct upon fuel prOductIon IS gIven cy fiemins ,:j. ,\ total of about 1.6 • 10° ,enle ies "ere register'ed in 1980 ,6:. nlS r,un>ber Cdn oe suboividea as follJws: c ;) o passenger ,enle ;es t r':JC':' 5 :luses motoreyc I es L igllt trucKS \' 10,000 Ib 9vw) ,'ep'-esent oDout ,,5' at tne truC~ tleet. The use at dies~1 fuei In passenge,',e'll- cles 'las incr-easell recent i) an.) 1'1 "93(;, diesel-powered passenger venlcle~ representee doout 4.4% ot new venicle regl$tratlons. ,l.ppro.imately 1.5 x 101( ·,enl~'e ~l:es rlere traveled in the \J~ in 1980 \0,. ,;, J,-ief diSCUSSIon at t"e .,,,mt,," ,';"1- cles~ injuf'ies .. and "jtalltlc'~ -'fVO:Ve'J velllcular dCCIGents ~I II Je ~resente(J 'd~~r ':>HVSICl.lCHEMICAl ?RlJPE'{TY JAT" The compa:rat i 'Ie safety asseSS~lent ,J1' :ne alternative automotive fuels CJnSloe,-ea 'ler'2ll1 relies heavily upon the fundamental >JnyslcJ- cne~,ical ;JroPt'l'ties .'t :ne "Je:s. 5e··:(~i'u property data tor these fuels "ere ~Jlnpl ie'1 ,l1eJ dr-e snown In T jnt -::, -~"" ~-»ec 1- .; lC-:it 1 c.n'S.. 'ilJ -:-" ..I S,=,O • I t,.j ~rODane 'n ~.cess :- 9~. , • _ •••• 7', .... I"1L""li.v 4 .. ,~·l .• ;- .. '-~ 0_". ." ,.lnj ,:ompdrj,:·.~ ~.:r~t~, ..:n.j'J') _"" assessment, 1t I> '-ecesSdrj ;er"", ,,':"" '-easonao; 0:' tne JI,en 'js:eff.. ':r"1tlC 3 i. t·,)'" r.t:' w '1L:; ... ~ .... :,- !>7i~! -:::,-- .i;teT'1d:"~t" ,q'~S~l~a!l";I). tp(:~,= :nt: (,lS ... .:t .J~ln9 :~€ •. :..z d r~; '-, SJec ,. '( ,';t;t, .-:.qrdt ~,:-"" "':o-:t'.:.' J:' Jr, ) .: '",vogen ic ; "mage ~:m_;,S;J1J91C.;· : jITj; .. : " : ~,-F1S J" ;tr-erd ~:'-..! :'1t:' ;H"l"TIc"'j "1 jZd"'C " '-': ", ~ -,., .... 010t\ 0, ;;" '..J ~t. ~ ... .~, ~ : .... :: " .... _ . ', .. ,-' ... ' ~ '1,,:" "~.::: .i" . ') ... j,: ~." : .. r ,.;: t." :- : .:i,t?-'·'J , o'--e j" .',r .. H)C ";t'!:un=: 1 ~n ':'"0:: ~ ,":,.- ~:~n ~~).ts, e.~ ... _::",,1'::' P1C t"~ 'j, h,::"'~ '"', ~'f",,::"", ~'t:-"~'" ... i.\"' .:e:e ,'"" )'J~-::J ::a~t?(J ... t.h)'· ~'ji::f",; :)rl.vt .. ··!. ~l'Jr:S 3iono:'. );11;;.:\912 ~'r :tllt?-,' :·-.(v'jf~'-i''':' ... t:'-:'i~ ~.l.n cool .l. ',oicJme .;t .l.'" ''TWf.t'J11t-=' .. . ; l:": - '. :~ •. !I. : ..... "n~ ~!l~ ":'~J~-Jt:.If' • I tne .·.:H.h_~r· ........ '.,,': .. : nt:: .: fJ09t:n' d 1 f" .~ 1 .. t .... r"! 1PP"'0dC'les. _,- J~C .i:,t! ~ 9'-~Jtt'r" tn-.lr\ :~I.jt :r i'r .. tntt- ,:'-:n:·. _3tJ "',c-t _,t': .J.j~·jL.":' -::5 .... ', .... teo .~:>"':':S·:J, ~(:,O::C .. ,.:jf- ,,·.:'·~nt -'itfi.JSly~tj, :)I,oICjoO(j n~('~d; .)lfr..,s~'ltJ1I ,J~ns,l:y .. fdDv'- .)'~el)sJ"'t' "e d t ) T , apo r ' l at ~ I) n , ~~n': '(F) ::..nt:l"-gJ, f ':1~n '-''J!n:, "'u: .... ';~nl: ; ..... n -t"O"PerHur", :;asn )Olnt. '~0r1ldt10n "Ht' ,-n"r"'ld; : 0 n-: ... e tl " t y. tie d t ~ ~O de ~ t J" _ -.)Q>Ov ; 1 t 1 0 n ::>ur'l'ng ',t!loc 1tj. :mlSSlvltj. neat ""it'dSe -<:He 0.5-4. I \. lst. IJ.iJ J 310-340 56\., . -. \ ... .,\,.. . .Jo>Ju4 1 ~ lq~lJ 0:.1 ..:ji.L~'!::'flt "'~p ~ner:n":·3 i. "1~t d ~ : ... rg li..~ d;" j,.}(j :"9 i n~~"'l!lg -~r:]Dt:'r~; ~s , .drlO,"S lSI The greater buoyancy of natura I gas (versus gaso Ii ne, di ese 1, and LPG) becomes advantageous in unconfined areas by permitting rapid dispersion and dilution. Confinement, on the other hand, can reverse the assessment since a fire Ind possible detonation hazard is produced quick ly. Hence the importance of defining boundary conditions for a given application or scenario. SAFETY RANKING OF FUELS A preliminary comparative safety ranking was accomp 1 i shed based upon cons iderat ion of the abso lute technical propert ies of each fuel. Each property is considered and the fue 1 ranked accordi ng ly. Effects of property interactions and other boundary conditions are not considered here. Rankings are essen- tially qualitative. it is recognized that the methodology is relatively simple and that realistically the final assessment must ultimate Iy take other f actors into account. It does demonstrate however, that o certain properties contribute more to hazard generation than others o certain properties are neutral, i.e., tuel rankings are equivalent o certain properties reverse the rankings generateo OJ ethers o safety ranking becomes a more complex prOblem Comparat ive s,3fety rank ings are ShO_1Il for a selected number of properties in Table 3. SECONDARY HAZARD CRITERIA - Fuels may also be ranked according to seconoary or sublevel hazard designations noted in Table 2. This was Gone In part OJ Bowen for nine tuels inciuding nlethane, gasoline, and diesel \:l). 'i3nKlngs. · .. ere maGe on the basis or 1-9, th" largest number inaicatlng the 9reatest '1al3,,-o. l)"r ana;jsis nas ;JrOLiuceo sWlliar n~sults .. ith .. t'G includeo. ::'electeo results ot .)ur' J.:1 .. 1!jS1S on the JdSl'), ;Jt l-o.l, tne 13rget~ number InGICdt ing the greater nazard, are ~resentea In Table ~ ,5ee footnote .~ "aole ~:. vnce Jgain, It 15 3.pparent ~hat safety ~dn"'lng Of tn1s tjpe "III jlelo ~drJOt.S '-esuits dltnougn there is a treno to crassify _"G 1na '-.ln~;ngs aiso suggest JleSe, ruei :0 :)e :nt' sdi"st. ~\J"Ic:1t.Y or emlSSIOIl Jdtd ,!lot snown; 'lay nowever Change the lDove. It snould De ._"nDnaS1Z,'(] 390:1n trlat ~dn~I'lgs are baSeO Sult'iy ~pon t~nnlcal Jata. Str-ingent Oounodry ~Jn01tlJns, ilppllCJticns, scenarIOS, dna r1S~ .Hlat''iaent st,'ategles are not 1nvol .. e<.l. ',,-: '-,lfl~lf)(l ,netnooologl ~0 'J" leta1:ei.l Ilelas S0me Idea of tne rela~l'/e ndlan.~s )f tne~,: '~eis. :)ut OIlIY HI a ,'!lost Qene,'al sense. ;n OdS1C d9ret~nent with the general concL..sions Jr riora, 3. ~eliltjwe Sdret, lna'jSl, 0r 11 te,'''/i[1 we fuels .. Ill no .. reQUI~e ~~ ~en€'rat1on of specitlc KClClent or lPpllcatlon scenarios ,.7 .• ~FETY DATA, TESTING, AND uPEKATIO:.AL REVIEII General motor vehicle accident data as well as those applicable to LPG-, CNG-, and LNG-powered vehicles have been compiled and revieweu. GENERAL MOTOR VEHICLE ACCIDENT DATA - Some pert inent motor vehic Ie oata are presenteo. These data were obta ineo from severa I sources ~2,6, 10). It can be assumed that the great majority of vehicles involved were gasoline- powered plus a sma 11 percentage under d i ese I power. In 1980, motor venicle accidents resulteo in6 51,077 fatalities and approximately 2.0 x 10 nonfatal injunes ot all types. The fatality rate per I x 108 vehicle miles was 3.38, per 103 registered vehicles 0.3, ana per 104 I icenseo drivers, 3.5. Vehic les involved in fatal accioents numbered 63,477 of which fire was reporteo in 1,720 or 2.7%.* .. e 00 not to date have details on fuel type~r whether explosions occurreo. Fire involvement aata in .311 types of aCC1(ler.ts can only be estimated. Some old data suggest that fires occur in approximately 0.1:1'. ot all accidents (11). This translates to approximately 12,000 ' .. ehicles. Passenger vehicles ana 1 ight trucks were the major venicle types involveQ in accI- Jents" 8~. Approximately 12 ~ 10° vehic~es or a II types wel'e HIVO I veo I fl acc i den ts. Head-on and various angular collision accidents representeo the two most promlnent multivehicle fatal accident scenarioS. eacn causing approximately 40:4 of ttle ace iaents. (Kear eno coillsions accountea for approxI- mately 30%.) Over' 60% 'Jt fatal accidents involved a single vehicle. The ~aJoritl Of fatal accloents occu~reo on rural roaas, approximately S5~. FInally, the rJS< c,t death occurring 1~ :l Odssenger .notor yen;c:e 3(C loe'lt .. as est 1I1;,H",c: 3t i 1-_'0 Je,~ :J:J ::>ef"Suns :'ef' -"ear dve,'dge(J '::,er ,) fears; . .... ?G ·~O~\"'~K fih:~_~ ~",.\"': ... ,t\t ... 'h, .... - S~·.H1S- n(S WpllCdD:" :,~ _,J."-i:h, ... ertU ~en1c;es 3re ~:cre Jltric",]t :C JCc;ulre JnoJ SuoseQ",,?ntlj }SSe'".lS.. ·.;tn~'~~n s.:'rJie r"S.;, ~'::'>St?~'filt2nt<:. .]r'~ lvallaDie f)r :d;-·~e",· .. me _53.;e 0t _t'G ,;ranne 5-~,ppln9 anG tt:r:;i(1dl~, )tcr'.jo.jt .. '~.~l • .inc :..3:nl(t2r t'~lJC .. sniJr.€t1ts s .... l.n .lS5eSsment') TId., ,.~ 1 .' ~ "'( ~ _ f" it;' I' '. ... j~tn0u9n ;e!e(t~~ :;1'''e''::S .lfi~ .... r~d'·J(.~et·J')~·_) :t i drge -:;( j; t' .j(( L~t.lnt 5 f'aj :Je ::ert ~ Ol~": . ~hese Idrge sc~le 3C~ 'dent Jat3 ,In,; :hOSt' ,;1td ,.":;ncernt?Q A:ltn .:: .;rs~.mer ;J,"('~· ... ct·) ,::'~~'fe~. Cdmpers, etc.! jre 'lot .j1W€n 'lere. Fo,~o ··'otOt~ l...Jtllpany· ;;€'rl)onr.t:'; ::st l·i:ale :'lj! t!1ere 3re 3DDrJ~lr.ldteL ~"C,~\..l' _"'I)-il0wert>c .t?~l( :es .;·n :'1~ .... ) "1~nw.!}) ;.t uO i e s .:'11 , 'Ie ~ 5 e : r _ r\l " "' Jln~ ... j ":;t"'- 111 ~'19"tle ~"'~l (0 ~erl "g } :0-,ear :6 1nJorea, ,na ;:'':'''10\1 '~5t~ ,~ JC": lJt>'ltS,. ~ .. ~, t ,n 3 ; : tIe s . ~ 110 t ne" «7~~iiTZ'dtTJO';'trl ·'dt ~i)'131 '11'~n""dJ )dtt'tJ "uRlI!11strolt l(n ,MUgUS! :-:lo~' . •. :.1"' • ---- --------- -- ---------- Taole 3 Safety Ranking of Fuels-Selected PrOllerties Flammability Range ignItion Energy Autoignition Temperature Diffusion Coefficient ~nergy Content-Volume Energy Content-Mass rleat Kelease Kate RankIng Urder* > (more hazardous than) NG,> LPG > G > U Equivalent 6 NG D > LPG NG .6 or G ·1'16** D > G '> NG > LPG Equivalent o c· G > LPG., 1'1G *r~G, natural gos-(rr;etndlle); L"G, liqu~'tiea ;Jetroleum gas (propane); G, gasolIne; J, (]lesel. **Uependent ~POfi continement. Taoie ~ ~elJtjve )drety ~anking or Fuels Odsed Upon ~econaarj Hazara ~rlterla* F 1 dlTVllaD i I j ty 1..,\G .,- _ H) vJSO~ ine " )n", r(adiat ion Jolat II itj _.is!! I I I ) Oispersion ,lJncontineo) 3 qua:itativeh ... ith ~lIe '11'1"e,' '-ul~be,-s S,l9gestl'lg ~iidt1lemdti;.Jr'·':"jt1:)f\Sr:iJ :-.et-ht:'err 'nl-~Se 'l,JL'lDE"rS -:"~l)tS. qurnber ..1 JO('S .~~~~~P:1!.:._i:..!~_·::lPl-L ~~lJt ~ne tuet 50 f'dted r.Jel "'jt~:lt1 ·' ... ·Oe'· '~l'J"::'n sec0fI1l1'·y ,:,'lterl::,n ;s greater jegrees cf ~aZdrd. 7nus, tor cAdl'lD ;-:, tne ~~Se ;.",r 1-; .l tunes. ;nOCt') ~:1laraOIJS :fldn ,;t)ne ,;0 tne ~ he :.! jc: llJent5~ most ~e \t'tnt'"t~ i :111uS ~I.j·'t· 1PP'-",\ "lutt: :_~ ;;>·.:'t~J.i. i 'JI!" \.\' ~~:"...J-L.\()~t?,~ ... ~.1 .r:?!ll(:e'::. ~n ~,J(\L1" n\, t '10 ~ r- j S 'I j r· ~ .' '-~)l .- ~ "uf,.,t't:O.- ",t • -:" 1 ( : t' ~ ... ~' .''1S I'; " ~t~(,t~, :: ',J Se ~ " • en ' ~ .':"""-, ... ere !'"''':Do,-tetJ ~_3:e ::-dfet.' :'~eSe :~sts ~·'1 '):vrj~e R 1 ~ ,., : • t· ~ t ' ") f S t tHll. _ \\ . .l ,\t\j ~ vl\ .. : r, ,_ i.. c.. -.L ..... : ~: c.. " ; ~,... : ,.~ _. j l J . n _\ll- ..... :\wt"·~1j n'JllC;e5 jr~c" rll.'I1.r.ai ;Jr~;ndr~1;"j ,JUe ',"t' .':.',', .~~'H .0::'/11_ ,:''::, :n.1~ .--t:"-e Jr" 3rt" ~;l .'(It''-it:UI. "It' ~t:H'tJ "dS P't: ~lgflt _OIliPdnj ."',ler-jt":""") 1l..· ... \' ... ~ ,~II~. ;er):~ ,to'). ~nt: ~·\..'llIPJny ~ i i :;r1""';, ~o'IIU ~J.:~ .lily .... .1," .. ' "r-: ~"jJ j,.):, 1 1,)11, "0 1 "J ... ,- J e1 OS ,. .~\..' ".3 ~ j j 1 t 't' ') • ne (.)mpdny j 1 '>0 .-~t.''.,.rt') ~nn:; .. ,::1 ."'j·J9~~n~,- :;un\ i1:C1Jents h.f-ln:1 :'·.In,tt''· J».·t't·HIJflS. _\u-f'Jt"C'u .'t'h1(;eS 'IJ~e : f" j '. e ; ~G jDP "".'", 1 m d t t? ; j _ " _ ' ,J 0 "'il: e 5 ~ 1 ."1C t' :9;:-. ".J j; ")(.l:e ->Jtety ~r-:lsn tests un ,-~G .t'nl( 't"' )t....:'·jlJt' ~jn~; I\er~t" ':..JnQu(t~11 Hi ;'"j~l 'Jj :n<, .) ~,epat-:'c<:?nt ,)t ·.·.ltlSportJl1.)" ~'v~,1 \ :-1). test l"g n3S :Jeen uone ~JS PJ~lea venlC~~5 ::~Pt~·J. H11d.t':";J 'i.,lfKt' ;::/.'0 I..,i' :nl 1-2':::0, r: 1. ~ :een j4.... ..... ..JlT'J: .Ht.·:";· "J.Y _ d j l!" .. 1("11 J. .idS _ompa"y 'Jperat lng _:1"\, ...... ~ !I : nt- \.'G":! ~ t :. ~t:' .............. : Flt,"l .lp~"'()Jll!11dtt: 1,1 cuV ,,'11):;':'5 .enl( :t's telt.}l )f') .... '·4U.. )OP1etn1'11) ; .. t)r~ ~')I~;· • .;tIU ~!'e reoo,'tea to De )perdt 1"9 "r. : : _~ ," .J' ..; j S ... ~G ~" II ~ 'U..l .. ":'~ .... 'Je"-t::) :'l\'1..':'~'1~ _\ll- •. h:"t'T-t",~ ,f'l'_ •. ~ j.jl;.j(,.~ ::ut ;s ~:)t;·Hateu t'J ut..~ -lvpr~c •... .,:;:~, :;.,uO. 't'ry tew l!lJ\Ines. no tdtdilt't'S • .1 '':"'" "11·':'~. j'hl qu t! .... iJ,·)S10I1S fIIere "'~".HJI-te\l. )dtetj lrnpdCt te5~1f')9 0n T'.Ji: -:,C.j;e ... ~.'I' ~:e, _t .':I~':I-1':1ob ,Intd.,)e .. a~ k~vf~.pll.,ne,j :', :ne ... J ~'\.." :4" :t -;nuu;J Q:~ '\\.1teu :~\dt :Jl.lll)'') """Jte-'·~(..HI n:'ru(.eS .H·t' ..:~.'nSl'·""Lto::G -l<.A~tc.' JI'te~ent if. r>e _.1nduJan uo~t'rnmt'nt n,L> "",-=",,:.! '_0I11tJ1",teC: ;<,("10:-' .or u .... act :i',ts .:, a )~'i~rjl ;;f-l'fdt~ .,:)n(~f-ns ~.jV~ (vnllu"::e"'; t .. !-~t~ }n ~ .... ej '::'J~!.~nl _.)li(H)n~f1!.),. ..:.~ .. ,. ... :Uji F ... i!i )~f"Vl(eS .. VP~'~..:tll'Jt;d j -eApef'"lt!flCt? :~. Jdt~ j':) ·-':'PI"..'-te\4 ------------ sa id t.; be very gooo a !though mdny note some technical and psychological disadvantages and have suggested selecteo improvements (16). lrrespecti • .: of the physical state in which natural ga~ is storeo in the vehlcle, vapor leakage int.o the vehicle is a potential prOblem. A study by NBS was maoe concerning vapo!" seepage into vehicle inter.iors and recom- menoations made to minlmize this hazard (17). Additional reviews of safety-related issues concerning CNG-. LNG-, dna LPG-powered vehicles are pl'lOned. Partial reviews will a I so 'De made ot 1 arge YO 1 ume LPG dM d,G sp i 11 tests. The data obtained may prove Jseful in our final scenario analyses. SELECTION OF CREOIBL: ~CCIOENT SCENARIOS To pursue the relative safety ~an;;et>--.: jn~ .:..' 11~ : t~ • ,:,'\: ~ ,.t: oe'l1C:t:' C::;l;iSl.::n/F· ... t"; ... ';";.S - .• 1",:" "'1~'l -.;~n':);t~ : .... Jtt'l. :_1:',. :,t?ntii.;.tlOrl ::JrH.]ltll..""l') general public. Our efforts will be to deter- mine whether or not such risk is equlvalent to, bet ter or worse than that a l.-eady acceptab! e using the conventional fuels. The program effort thus tar nas not jet reached the ana 11si s stage. Our pre 1 imi nary thoughts will be to consider existing levels Jf risk, these to be modified oy constraints imposed oy the cnosen scenarios, ana f 1na]lj ,0 est imat€ the ri sks imposed by the use ot alternatIve fuels within those scenarios. To assist in the riSk est imat ions, it '" tentati .. ely planneo to elicit lrltormdtIQ" .,,' jUdgment by convening or mail surveyIng 3 ~rcu;; :;f experts. FOur met n,,.J";~':!t::'~:~ :r ~';e .t:" .... r. I-·~ ... ',C '1e ~""_,.'":)~ i~ ·"~~·tjt-;:...: .~lt' ~ nt- ~ t? ; ~ ~~ 1 .JnS€·'5~') 1 S ·'edCl1ec. ',t:' .. \. , .. ~. ~ I. . ~: ~ , .: ...... ':: -: . _. :.~ e ". -:. • <:: : ':."'. ~r jpn 1 '- .1 ; ';0~:':I '':;, c:' .,..fllCn ..... Hi .: .... ,: !".! .... 1 .!rl..J .... t?s ,.2 t '.~ .":C ... .~~ . :.",." , . ..; i ... j . ,-rr:d" "'e .~'" _ ... _ -.' .. ~.It:"" t s ·r-:.,"" ,.: -.... ". "e _ ~.:::-. ~ ~ ," • ... ,' :~!' "' •. , ..... !",;, .... ,.,.,;.::' ." ...... jflJ. ;.' ~ I '} repr~S~'ltjt'Jn ., ~wt."nts ·~r· ).)~t·'~ analyzed for varIous ~ays by wnicn it may occur. Edcn s"bevent is SImi lariy analyzeu. One drrives finally at a basic level ot events or Illtor'mation wnere probabilIties of occurrence or values dre known with a high degree of coni iuence. Tne Saaty paIr-comparIson tecnniQue con- sIders a partitioning of the analysis into several suoieveis aimeu dt generatiny d spec if ic Index value (which can be intercom- pareLlj :or each f"el wltnin a given scenario. It is basically d scorIng methodology. The tt'cnrl1cal propel'l: ies or trle fuel provioe tne basis for the oUllclJp of several levels to tne final Jete,"nination of the index walue., viz., teChn ICd i ;;ruper'ty Intorl1ldt lun--seconuary Suo- level hdlard--prlmary hazard--Index val~~. \),'" ('I"'ent lno~ghts lean str'ung If to Uk "se ot the ':lroup consensuS methO~ for el ie ita- lion 0t 1r1l0nlldl Ion am] tIle )ddtj teCJlnlque as a scorl~g methOdology, J ,)Ilj') 1 ,_,;\". nf":! 1 '_ ,j, 1 t1rUOer~t y Jj 1. ,} ... ~en~r-Ji ,JE:tl-'J~e'Jn; 3.rlu 'le~llC;e ; ,.:t ! j·:L 1 ,ll _.~,<~.r!l~,~··} J"L~;-_· .. el ~.r '11(: :r·0') ~t:l" eu "",;S "Jn~"t.! :JdSeLl ,.pOIl Dctn ~'·'·;)O~\··t les a !une JflJ en ~ntel':iCt 1 ve ":at,., ( ,)T.l: .... :;J:tJ. ,·-=:v1t:' .... ed ~,:':... '-:.-It~ ':-:t:'!I"i'~l~~S Se,eLtt?J :1~t,:"~(+.J":; :).J.~et .. In):JS1S .1'1(1 ,:' l· .~ r' 1 S ,r~ : ,_'> :)~ 1 r~ 1 t ~ .... r ell • . :' ) .. ~ " :: . :.,: " jt'l..:nt .... ~,·\...o, .. \at .... ,·ji )J.fl 6. 7, 3. '3. ,J. Transportation :>atety Information aeport. U~ Department ot Trdnsportation, report no. UOT-TSC-R)PA-Bl-7 (June 1981). J .. Haro. "ls H:,;ur(.I1:lt::!rl Sdte?1I Note 690. National Bureau (uctooer 1970). r;1:l~ Technical of )tandarcls T. L. tlowen, "Hazaros ilssuc ialeo with Hyol'ogen F ue I, Proco:eO ing s, ". (September 1976). Eleventh IEeEL MeetIng I, Lake Tahoe, LA 5. l.ewis anO G. von E lne, COfTlDuSt ion, Flames and Explosions of Gases. 2110 Eo., AcademIC Press, New YOrK \l9bl). Fatal Acciaent Reporting System, lYBO, uS ~ePdrtment of Transportation, ~atjonal HIghway Tr..ctt It: Satety lIoministrdt ion, report no. DOT-H:>-305953 (October 1981). il. ::'jmpOSlurn un ilOllp"troleum Vehicular Fuels iI, Institute of Gas TeChnology, Uetroit, Ml \June l~-Il, 1981i. ,_, J. )i..nuitz, :)y~lpos i "m at ~pe( I d ieul. "L "-Gas htn ,ISM!:. ;)uL i. :;25, lnglne r.els," Meet ing, IISTM LOS Angeles, eM Idll wer "O:I,J", ")dtetj rest 1'19 ,I L;'>b "no Gas-Fueiel.l lehicles," )ympOSI;;1lI 'In :wllPetrOleurn 'Ierne.la,' ruels, illstltute Dr c'as TeChnology. "\rllngton, ." ;FeDrUdrj : i·· 1 j ~ 190U). \10Lw ielll( ie Jud;-f lIe 1 :esting, vS ~)eDar~:nent .::t ~att'tj ~:r~ldC:' iI' jn<,pon ~t 10~ .... t:p.jrt flu . • )\j~, n~-:~G06~~, JjndlT:l~ :;:= 1o::nCe, ~ll .. 1Sl']n Jt ".1afsn . li! ::hJl..tstr~es .\0'./ "j. ,. ~·.::'~,::-pur~t ~j!i,~I..!.!, \l""~J'- .en'·:.':: ·-j,rr . _ _ '..l ret .. l :) ~ l nc ", ;:'.::' j ~ j t e t}' ~ '~)P :( : ~.~-:- ... ~r~_\::'I-.iil', 1II1~:t:r' ::13.-;'1, .. "'_ . .i'-: .ill ~ an ~. or'~lJJ"'t''''' _ .Jfle ) 9d:. , . "'etnalle-r ... ~ ;,~,,; t>":9 11~c' j j '::, t elllS, .. r' .~ J I f't?D0,·':. • _1' .... ..:') "est'"rl!1 :,.,q It"te, _1..1ntr~jC: ,0~ "'-1.'" '·~t!'..... ,)~ JJ:>t:vu':=l ;:j'J"0~t'n "",=,tr:dne ~V.e~~ r(~\m tnt:! :'~tcrl'Jr I,.',t <~n .fo\~tJIThJ':':J t:', ".0) .':'C""'fll .... J. ~0t~ 000 ,~..ln.:!l ,'j - :: .:iii: j , ~(\.}t· 3ft QUEST IOI~ AND ANSWER PERIOD Q: Ralph Fleming, Department of Energy. I'm wondering how you are going to guard against the situation that one of the speakers I~ent;oned this morning, namely. that in ref,erencingproperty data, have you listed older literature? I suspect some of these numbers you have were determined in the 1920's. How do we know how good those ntmlbers are? A: This is an unfortunate occurrence in the sci enti fic literature. I have run into this with my own experimental warlc, in that data tends to get reproduced continually and is actu,ally out of date. Our best bet here is to re~lly go to what you consider your best sources, e.g .• people who are worlcing in the field. and attef.1l't to aCQUire the latest data available, if it's available at all. I might find information through my contacts, I !Ili ght go to the latest meetings. for example. a particular fue I sand combusti on meeti ng and atter.tpt to CJntact various people be they in universities or industry. Q: I wondered how rigid your programmatic restrictions are. Is there any possibility this study might encompass other fuels lilce methanol? Methanol seems to be emerging these days as the most 1ikely candidate alternative fuel to become available in substantial Quantities in this country in thi s century. A: I'm not certain to date whether there is a similar study going on with methanol. It certainly should be done sooner or later. But this again becomes a function of both interest and available funding. The Department of Energy should be contacted as to WIlether or not we wi 11 do a prog'·am 1 i Ice that. Research Investigation of Alcohol Usage in Spark Ignition Engines Research investigations of alcohol fuels for automobile engines continues to show alcohols as viable alternative fuels to gasoline. Howeve,:" some technical problems stlll need continued research before alcohol fuels enter the public sector. These problems are cold start:n~. :ncreased engine wear, increased aldehyde em1SSions and the unknown Lmfact of these fuels on the enV1ronment. Research at the University of Santa Clara :.as continued to center on these ?foo!ems ~nd a descrlption of this researcn ~s ?res€~nted here. -;"HRGc:::;ti :-l ':.':::\RS ·)F C::ONTI~UED RESEARCH on t~e ~S~ )~ 3:~on~1 f~els:n 3Jtornotive :3:J..3~' i.l;~:':' __ ~;: e-:I'll:1eS, ~:1e ::'asic alcohol !:~~t:? ~.: 7:e':~,-iTl\"'; ~ ind e~:~anol) :13.Ve :)ee~ 3~0W~ .. ~ ~e 0ftlcl~nt, ~lcan ~~rn!ng t~e~;:; :.)~ 3Jt0I"r.ot:',Je -..4se ~~,2,31.* Howe\·~r, ~et,~[e t~lese ~~~L~ can become ~,-)t3~_.· ~.):run·2~c;'3~:.zed, there .:ire 5tit:. some ~~J~~~~S :~at ~eed to O~ so:ved. ~h~se'?~02~ems are C01J start~ng, engine Wt'3~·. 1 :de:l\'Je t:iTI13S l.ons .3.nd the .Jni_ ~ : ~ ': j .i n j :- .:? s e .3. [ -::1 ~ s '-~ ~.., r. ~ :. :1...1 1 :11.j ':. 0 3 .... ;~·:e :::~;r.. '!'~e to.L.:0Wl:1..J paI?er :.-Jl~.i eX?~ain some of the researen ~e1~g done a~ :he ~nlverslt~ ~f Santa ~iara ~elative ~o ~h~se proolems. ~_. i stdrtaol.:ty ot 3~c~n0: t~eled ~~:~:~:~5 :~ 3n :inpor~ant issue SInce the :rte:::c'cove. Even wlth exhaust heatIng of the 1ntake mixture, there is a short period of time during which intake temperatures drop instead of rise and a smooth idle is difficult to obtain. This fact leads to point two: . an auxiliary f~el system (i.e., gasoline or related f~el) cannot be a simple one-shot device. Rather it must ~e capable of fuei jellvery t~rough at least part of the warm-up period and this Jreatly complicates the ~ecessary nardware. Thirdly, no reasonable, SIngle, auxillary cold startlng techn1que was capable 0f satIsfactory start and war;n-~p ?errormance other ttian aux11Iary fuels such as dissociated methanol, gaso~lne, d1-methyl-ether or butane ta1l~red for cold starting and warm-up .... 1peratlona F'~'om :-.!1t:'se st3t.:-men~s, ....:-ne concl~des that the best S014[10n to the cold starting problem ~as ~ot yet ~een developed. . ::>roplet transport and ·Japar I~at 10n may oe part of the 5014t1on to cold starting and warm-up proolems w1th alcohol fuels and is current~v our area of eroohasis. ~hlS area 1S oel~o studled through Doth computer :node~s 0f - :~e ·;;old start er.glne ?loceSSes and an experlmental study 1n WhlCh ':In engl:l€ .s mounted ln a refr Igeratlon :::tlamber· oil th lnstrumentat~on to measure the vaporizat1on process. COMPU'rER MODELS - In order to study droplet transport and vaporization, a sophisticated one-dimensional, two-phase flow computer model which simulates the gas exchange and compression processes occuring in a spark-ignition engine has been developed. The model selves the basic unsteady conservation equations for both gaseous and liquid components at each node in the intake runner and engine cylinder at each time step. Thus 13 derivative equations are solved at each of 20 nodes during each time step during a cold starting event. While the time intervals are determined by an error criteria, the average time step is ap~roximatel¥ 0.0025 crank angle degrees. Th1S model 1S written in Fortran and e~ecutes one complete crankin~ cycle on a CDC 7600 computer in approxlmately 200 CPU seconds. A color graphics display is then used to visually study the droplet transport and vaporization processes occuring in the intake runner and engine cylinder during a cold start event. Initial studies, however, have broken this model into two sub-models. These are droplet transport down the intake runner, and compression of the 9as and droplet mixture in the englne cylinder. The results from these two sub-models are presented here. The droplet fall-out and sling-out sub-model is used to examine the fate of droplets in the intake manifold. In this model, plu9ged flow along a two- dimensional 1ntake runner was assumed and the conservation of momentum equation was solved in Lagrangian form. Droplet transport ~o/as calculated from drag forces imparted to the droplet, while gas velocity was assumed constant along the intake runner. in Figure 1, a gas velocity of 275 em/sec was used to simulate a cranking speed of 200 RPM. Droplet trajectories for various sized droplets ar~ plotted within the runner. .... " .. ~ vp. ;:-::,._~~ :.=<::~_~" ~.,. <_ ... ,= s ... :':.-..::~ ~ Y::':::E_ ,:-~ ::;~~ ..... E_X:·' ,?-s :\4.5[: • l , -. ~.E- };:~ -_ .. .: ~ ,_ .2'5..J1l .~._ 5I:.J< . __ .x: .... -~- .... - ~ .... -.. ~ ,. . .", __ ::;oo~ "·-~-"--·"··~·r;"'-'1~--,---r-~r.~r~·-r;r;r;;~-'-~ As can be seen from this figure, tne 10 and 25 micron droplets will enter the cylinder while a 50 micron droplet will fallout of the dl~ stream before entering the cylinder. The 100 micron dro~let is shown to be slung out in the manlfold corner. This is due the fact that the larger dro~lets have higher downward momentum dur1ng travel in the down-draft portion of the intake runner, Figure 2 shows the effect of air stream velocity (or cranking speed) on the trajectory of a 50 micron drop:et. As can be seen from this f!'-'.!re, the slowe~ the air stream velocity (slower cranklng speeds), the larger the chance of the droplet entering the cylinder. The second sub-model examines the fate of droplets during the compression ~rocess. It assumes that all the fuel lS 1n droplet form at the beginning of the compression stroke. Both heat transfer and droplet vaporization are allowed to occur during the compression process, Figure 3 shows the cylinder pressure during the compression stroke for alr only, air plus methanol, and air plus ethanol. The starting conditions are 298.15 K, 0.775 atm, a compression ratio of 10 to 1, a cranking speed of 200 RPM and a stoichiometric mixture of liquid fuel ~roplets and air. Initial droplet Slze 1S set at 50 m1crons. As can be seen in this figure, there is 3 substantial reduction in final c¥llnder pressure due to fuel vaporization In the air plus fuel ~ases. As ex~ected, methanol shows the greatest reduction in final cranking pressure due to its verv large heat of vaporization and its largei fuel mass for a stoichiometric mixture in comparison to ethanOL. cylinde:- for the methanol Figure 4 shows the temperature versus crank angle same comparison. As expected shows the greatest reduction cylinder temperature due to its in tina: high heat :,,"'.r- U I 6+ ~-M-l I •• 1.00 I , 10.1 ell J' I 200 RPM L2Q~~ ___ ~ AIR c.I _2'l._~_JRC~~. ~ .. ~:;;t :;I'L ~ ,~ c-'W'Ol ",,-~~,,'Ol ~ ;---;--·~-----;-·--ao-·-;)~ '-:-;~--:60~-:00 ::RA.'>'X ~N'""L.t: ::£GRf.ES C~OO() Fl GURE 4. CY:": NDER 'EN?£RA T:..f<£ FOR R00I4 ~[)(l'£RA':;R£ ::RANike for room temperature cold starting. It also shows that ethanol droplets vaporize more readily due to the lower heat of va~vrization and lower fuel ;nass. The same comparlson is shown in Fig~re 6, but for a starting temperature of 0 C instead of room temperature as in the previous graphs. As shown in this figure, the methanol vapor/air equivalence r .tio is below the lean flammability lLmit at the end of the compression stroke wnile ethanol 1S above. Thus a methanol fueled en9ine canna: be started under these conditlons without additional starting aids. Figure 7 shows the effects of various droplet sizeE on fuel ~apor!air eqUivalence ratio during the compression stroke at a starting temperature of 0 C. As can be seen from this figure, droplet Slze is very important in the startability of an spar< ignition engine. The figure shows startability of a ~et~anol en9ine Wltb. 10 micron sized droplets, whIle the 30 a~d 50 micron droplets do not provIde a :ldmmab~e mixtJre at the end of the compression ,c:o;;e. < '" :.8+ L3 !.2+ z "" ..J < ;: 4.:J~ :::l o .... '" :;: l.8+ [\ Co r------, : 2!18. 15 ~ •• 1.:JO 10.1 ell 200 RI'I4 so "" 0iU'S __ ~ET~ __ M8lWIOl ;! J..fJr--·------- Tao tro +60 I 2.°T l.a+ "! 0 1• 4 ... < a: t! 1. Z ~ < ;: 1.0 ::> CJ UJ a: < a.O ~ < :> a.S a. Z . a.o o 2.°t 1.9 o :-:t I .< I ~ 1.2+ ~ I ~ 1 ~ t' § 1.0 '" ~ 0.8+ ~ > (\.6 a. 4- 0.2 a.o o 273.15 ~J •• 1.00 ,0. 1 CR ZOO RPN 50 "" III!PS -'-'-"--~ LEAN FUIIWII LI TY LI H IT ." ......... '""" \ \ \ 9D 70 60 / 20 ; / 20 . ~ / ,. / /' / /// ,/./ I I ->4J!=--'~::::::'-+---+--- 40 60 80 100 120 140 :60 CRANK ANGLE O£GR£ES (ABOD FICURE fit FUEL EFFEC"S AT 0 C CRAKKING r;~l I •• 1.00 I l tlETHM'OL I 10. 1 O! _ 200 RI'II I _ 51) "" DROPS ___ .30 "" DROPS __ 10 uM OROi'S o 180 10 F1Gl!R£: 7. Ofl1l!'lET SIZE EfFECTS AT C CRJOO(ING 310 Figure 8 shows the effects of cranking speed on droplet va~orization. As can be seen from this flgure, the slower the cranking speed, the more time there is available for droplet vaporization. Still, even with ~ cranking speed of 100 RPM, the 50 ~ic!on droplets do not provide a flammable mixture at the end of the compression stroke with a starting temperature ~f o C. Pigure 9 shows the effects of compression ratio on startability of d methanol mixture of 50 micron drops W~:~ a starting temperature of 0 C. As can 0e seen from this figure, modest changes i~ compression ratio have only a slight effect on final vapor/air equiva: ~nce ratio. However a very high comp'€" .sion ratio like those seen in diesels, c~n provide a flammable mixture while nor:lal compression ratios can not, especia~li with the fine atomization of the diesel injector. EXPERIMENTAL STUDY In ordee ~~ provide experimental verification of t~e findings thus presented, an engine mounted in a refrigeration chamber ~s instrumented to record cylinder press~re and temperature during a cold starting ~vent. Figure 10 shows a schematic ~f this experiment . The theory behind the cold chamber experi~ent is based upon a simple enerJY and mass balance of the mixture trapced in the cylinder dur ing the COtnl;>.fess"i::m stroke. The energy balance lncludes cylinder leakage and heat transfer to t~e 2. 0- 1,8 1.5 • ~ 1'·1 -< a: uJ 1.2 ~ I .J ~ 1,0 ;'; 1 273.15 K •• 1.00 I Io£TfWIIl. I 10.1 CR L-50 uM DRCf"S __ 100 I!FI4 ____ 200 _ __ 300 _ ~ o.St: ~ -~~~~~----------- - G.6 cylinder walls. Droplet fall-out and va~r condensation are not modeled at thlS point. I.eak rates are determined from a dynamic pressure meclsurement in which the cylinder is charged with com~ressed air at constant piston posltion. Oncl~ the leak rate is known, an estimate of heat transfer can be obtained by comparing the measured air-only cycle to a cycle coroputed using the calculated leak rate and the conservation equations. With the leak and heat transfer rates quantified, the guantity of fuel vaporized per unit time 1S bac\,ed out of the calculations by comparin~ the calculated pressure trace to the alr plus fuel cycle. Whil. this approach is less sophisticated than the one-dimensional, two-phase computer model mentioned abov~~, the two approaches work hand-in-hand in providing a better understanding of the fuel vaporization process. Measurement of droplet vaporization during the compression stroke opens a number of interesting research possibilit.ies. The first application is ~Ol 10 91 106T !:,:!ut ... , ~ I.zl ffi ! 0.& (U - o.z I~~ I I 200 RPM I so "" llR(i'S I _ 10.1 CR ___ 12.1 CR __ 1411 CR ____ zo.l CR '...EM <'.NWI! II IV II ~ IT ----_._----- I ----j; lV;' /f; /'/ a. 0 -._-__ .... - 1~--+----+----4 Q ~ ~ 00 ~ ~ ~ ~ ~ ~ CRt~: AN:;U O£GREES CAOOO FIetru:: 90 ~S;lON RATIO EfFECTS FI»l 0 C CRAf«ING to be an investigation of droplet behavior to reduce the temperature at which pure alcohol engines will start and warm-up satisfactorily. Other application~; include the effect of droplet vapc)rization u~on the compression work of a running englne. It has been hypothesized that with alcohol fuels this effect upon efficiency can be significant. Regarding combustion modeling, with the state of the mixture known at the time of ignition, more accurate modeling of warm-up perfocmance and exhaust emissions is possible. ENGINE WEAR Engine weac resulting from the use of alcohol fuels has been documented by several researchers[4,5,6,7]. It appeacs that alcohol increases wear in automotive engines from 2 to 10 times that in gasoline engines de~ending on engine type, driving and cl1mactic conditions. The reason for this increased wear is not well understood, although many speculations of possible wear mechanisms have been made. Research at the university of Santa Clara has examined wear by examining the ~?jor factors which relate to wea~ and corcosion in automotive engines. The most serious -:ngine corrosion and wear problems appear related to the differences in the products of combustion among the alcohols and gasoline. The effects of excessive cylindec wear, rust colored compounds formed on icon parts bathed in oil and crankshaft bearing failures are believed to stem from two sources: (1) The increased water focmed by combustion of the alcohols which elevates the dew point temperature of the exhaust products. (2) The increased acidity of the condensate formed on cold sucfaces. The calculated dew point temperatures for methanol, ethanol and 9asoline when burned stoichiometrically 111 dry air at one atmosphere are shown in Table I along with the measured pH values of the condensate. The condensate was obtained by passing exh.aust gases from the en9j~e exhaust (ahead of the catalys~ '_nrough a carbon dioxide cold trap. The high dew f;>Oint temperature for methanol combined wlth its high heat of vaporization clearly indicates that the warm-up time for a ga.soline engine convected to methanol will be significantly extended. In addition, the amount of combustion condensate and unbur.ned fuel collected on the cold cylinder walls, valves and piston faces is estimated to be twice that of 9asoline because of the extended warm-up tlme and elevated dew point temllerature. When these factors are comb 1 ned with the measured pH values of the condensate, a major source of corrosion and wear in methanol engines is identified. One last mechanism which needs to be explained is the fact that the presence 311 .-- .:::- ~ TABLE I, COMBUST!ON CONDENSATE .ACTORS ~_ COIIBUSTION ctNlfl'6AT£ ~TlES l-~l- DEW POINT TElftRATlIIE ll:~) i pK I : I ~~.~ I •..•• -=..~ :....'"lIl.t6.5 ~ I EnlAQ. 56..')..137.5 2.2" J GASOlI"" ';<'.: ;,'6. ~ ,. '5 of alcohol 1n the condensate significantly rea~ces the surface tension of the condensate. Si~ple experi~ents with watch glasses coated with engine lubricating 011 indicate that ~ethanol added to a dro~ of water enaoies it to spread on the oll film possibly reachlng the glass surface. ~ith aCld added to this condensate, a corrOSlon theory can be develo~~ which can explain the severe corrOSlon and wear encountered in alcohol engines. The alcohol in the water may provide a conduit through the thin oil films plated on the iron cylinder which will allo" thp. acids in the condensate to attack thE~ bare iron surface. Acids, such as nitric and formic which produce hydrog~n ions, can cause local cell corrosion forming compounds such as Fe(Ofl) 3, t-'e(HCOO) 3 and Fe(N03) 3 which are of lower density than thp. base metal. These compounds are easily re:JlOved by the sliding surfaces, thereby causing rapid wear. In order to understand the high pH values in the ~ethanol condensate, equilibrium calcul&tions of methanol, ethanOL and gasoline exhaust were done Jsing a NASA chemical equilibrium program[8]. This study sholoed that formic acid (HCOCH) was formed at h:'')h ~e~peratures and was hlghly temperatJre dependent. Figure 11 shows compar1sons of the exhaust of methanol, ethanol and gasoline at 1800 K as this represented the high end of exhaust temperatures. As can be seen in this figure, equlli~rl~m THERI4OCOUPLE (0. 0005 M DIM PRESSURE FUEL INJECTOR \ ~ .'"> TRANSOUCER '-"r---# INSTRUMENTS AND MEASURED QUANTITIES - CYLINDER GAS PRESSURE - CYLINDER GAS TEMPERATURE - THROTTLE & CHOKE ANGLE - ~ANIFOLO ~ACUUM - ENG 1 Nt: SPEED - ENGINE TEI4PEHATURES - ""ISS fUEL INJECTED/S rROAE SHAFT ENCOO£R - POP 11/03 DATA ACClJISITlON SYSTEM ENCODER FIGURE 10: 2.3 LITER rEST ENGINE IN COLO CHAMBER 372 ~--~- calculations do not show significant differences betw~~en the three fuels but do show that formic acid formation favors rich mixtures. Another possible acid elcistent in the exhaust from these fuels is nitric acid (HN03). It can be formed from N02 at low temperatures and the equilibrium exhaust concentrations for the three fuels are shown in Figure 12 at 600 K as this represents the low end of exhaust temperatLires. Ni tr ic acid i5 shown to form 1n lean mixtures, but again there is little difference between the three fuels. However, high N02 concentrations (far above eqUilibrium concentrations) are found 1n the blow-b¥ gases which mi9ht promote the format1on of nitric aCid at the low temperat~res found in crankcase conditions. Further studies whiCh Involve chemical kinetics need to be done fully understand the mechanisms of corrosion and wear. ALDEHYDE EMISS IONS Aldehyde emiSSions from alcohol fuel~d spar~ 19n1tlon engines are typically !-:lgher than those from gasoline fueled engines. It IS generally accepted that al,1ehvdes are formed from lean partial ccmbustlon of alcohols and are prlmarl:j formed In the exhaust s;s:e~!'g,~~·. A:l ~x=ept:~~ ~o thIS fJ:e -. ~ :8GC r<. __ __ OCETHAIIDL _____ HHAIlOl ______ :;.ASQ j Nt: .-/ -' ;:;~::-~:~ i~' ;> /" /f /,/ -12 L_._v_ ...... ___ 9_. __ ·~~_· __ ..---·_H.". ___ ..... 0.. , :l. 6 0.. Q :. 0 :. 1 :. Z !. l Eatll V AL£NCE AA no ~--.-::---. ~------ 31J is when alcohols are burned at rich stoichiometry in an engine with an exhaust catal¥st and an air pump. Under these conditlons, the catalyst can actually form aldehyde emissions from the unburned fuel and injected air particularly under lower exhaust temperature conditions such as during extensive idling. These conditions duplicate the standard methods for making aldehydes in the chemical industry. These conditions occurred with several U.S. Postal Service vehicles converted to alcohol which led to a temporary suspension of fleet o~erations. The difficulty ste~~ed from the previously mentioned factor and the fact that the mixture of the vehicles was inadvertently set too rich. This latter condition has since been corrected. Additionally the driving cycles for these vehicles (10 miles/day) are such that. ~he catalyst never gets above warm condltion. Studles of this phenomenon and solutions to this problem are currently underway. The experience the U.S. Postal Service 1S having should be noted for two reasons: (1) Aldehyde emissions (and more importantly carbon monoxide emissions) from alcohol fuelod and gasoline vehi~les can become serious problems f~r the vehicle operator. 12; Lon9 Defore this level lS reached, 600 K. -lO~ ~.-:~ .~ -12 ~. -12 ...... -15+ ATM _ _ II!£THAHOI. --__ ETIWO. __ GASOlINE -16 L-._--___+_-__+_ I .-.. 0.1 0..& o..\l I.D 1.1 1.2 1.3 eQUIVAlENCE RATIO FIIiUIE 121. EWILlBRltJt NITRIC ACID COWCflHRATIQNS " / lower levels of formaldehyde and carbon monoxide may pose health problems to operators exposed to partially reacted exhaust for extended periods as they may exceed OSHA carbon monoxide safety standards or aldehyde levels above 1 ppm where health effects are noted!ll]. Figure 13 compares aldehyde emissions from an in-tune vehicle (PS '2) to an out-of-tune vehicle (PS '10) from the U.S. Postal Service alcohol fleet. As shown in this figure, PS flO emitted 2 to 3 times the aldehyde emissions of PS f2. The over-rich condition was due to both the sinking of the carburetor float due to methanol absorption and to an overly rich idle speed carburetor jetting. When both these problems were corrected the emissions from PS flO were brought into line with PS f2. While carbon monoxide emissions are not shown in Figure 13, PS flO emitted 3 to 4 times the carbon monoxide emissions of PS f2. Replacement of the carburetor float, however, made little difference in carbon monoxide emissions in comparison to PS 110 as received. ENVIRONMENTAL IMPACT The storage, distribution and use of chemically pure methanol fuel appears to have a beneficial environmental effect in comparison with the storage, distribution and use of gasoline or distillate fuels. However, more detailed modeling studies are needed to account for the net changes in emissions inventories under various end-use scenarios in the stationary and transportation sectors. In addition, the photochemistry of methanol should be validated when hydrocarbon emissions and methanol emissions are combined in computer models to predict urban ozone pollution effects. The interactive photochemistry of methanol emissions with the existing FIGURE 13. F1P AlDEhYDE EMISSIOH RATES 31. fossil fuel emissions is currently being studied in a photochemical smog chamber at the University of Santa Clara. Earlier studies wi~h this smog chamber have shown methanol and ethanol to be relatively unreactive in creating photochemlcal smog. Aldehyue emissions, however, increase the photochemical reactivity of the alcohols!21. A cryogenic trapping and gas chromatography technique has recently been developed to measure hydrocarbon concentrations down to a few parts ~er billion. Chamber characterizatlon studies are underway in parallel with a series of basellne urban mixture eXJ;leriments. Multi-client support is belng sought for the experimental work and subsequent photochemistry validation and computer modeling studies. In contrast to the anticipated atmospheric benefits from the use of pure alcohol, blending of volatile hydrocarbons into methanol for cold start and driveability reasons, may increase the mass emission rate and the reactivity of the blended fuel's evaporative and exhaust emissions. These effects are also currently under study for the most likely fuel blends of methanol and iso-pentane or gasoline. CONCLUSIONS Alcohol fuels ace clean burning. efficient fuels for aut~~otive use. The alcohols provide some continuity in international fuel supplies since alcohols can be produced by even underdeveloped nations. Production of alcohol as an alternative fuel to 9asoline is already begun in Brazil and lS the top most choice of several other nations. However before complete commercialization of alcohol fuels can begin, some technical problems need to be solved. These problems are cold star ting, increased engine wear, increased aldehyde emissions and the unknown impact of alcohol fuels on the environment. Research is continuing to study these problems and solutions are withln reach. ACKNOWLEDGEMENTS This work was funded under NASA-Lewis Research Center Grant No. NAG )-143. REFERENCES 1. R.K. pefley, L.U. Browning, W.E. Likos, H.C. ~~ormack and B. Pullman, ~Characterixation and Research Investi2ation of Methanol and Methyl Fuels. ERDA Contract No. ElC-76-·S-02-1258. University of Santa Clara Report No. M.E-77-2, 1977. 2. R.K. Pefley et .ral., ·Characterization and Researcb Irtvestigiltion of Alcohol Fuels in Automobile Er~ines.· Final Report. DOE Contract No. DE-AC03-78CS. universitr of Santa Clara Report HO. ME-81-, 1981. 3. 4. 5. 6. 7. 8. 9. 10. R.K. pefley et al., Research and Develo~ment of Neat Alcohol Fuel Usage 1n Automobiles", a Six-Month progress Report, NASA-Lewis Contract No. NAG 3-143, July 1981. R.K. pefley, "Alcohol Fuel Corrosion and Wear Effects," presented at the UNIDO Conference in Dehra Dun, India, October 1982. W. Baisley and C.F. Edwards, "Emission and Wear Characteristics of an Alcohol Fueled Fleet Using Feedback Carburetion and Three-Way Catalyst," proceedin9s of the IV International Sympos1um on Alcohol Fuels Technology, Guaraja, Brazil, October 1980. E.C. Owens et al., "Lubrication Requirements for Alcohol-Fueled Spark Ignition En9ines," proceedings of the IV Internatlonal Symposium on Alcohol Fuels Technology, Guaraja, Brazil, October 1980. G.K. Chui and R.E. Baker, "Lubrication Behavior in Ethanol-Fueled Engines," proceedings of the IV International Symposium on Alcohol Fuels Technology, Guaraja, Brazil, October 1980. S. Gordon and B.J. McBride, "Computer program for Calculation of Complex Chemical Equilibrium Compositions, Rocket performance, Incident and Reflected Shocks and Chapman-Jouguet Detonations," NASA Report No. SP-273, 1971. L.H. Browning and R.K. PeEley, "An Analytical Study of Aldehyde Formation During the Exhaust Stroke of a Methanol-Fueled SI Engine,· proceedings of the IV International Symposium on Alcohol Fuels 7echnology, Guaraja, Brazil, October 1980. K. I to and T. 'fano, Emlssions from a S1 ~ethanol,· proceedin9s International Sympos1um fuels Technology, Ca1iEorn~a, May 1979. "Formdldehyde Engine USing of the II I on Alcohol Asilomar I 11. "Formaldehyde and Other Aldehydes,· ~eport to the Natlonal Research ~ouncil, ~ational Academy Press, 1981. 315 QUESTION AND ANSWER PERIOD Q: Robert Pottel", General Motors. Regardi ng your slide 4" I believe isn't one of the major factor~; in the cyl i nder temperature the IIIdSS of Dlethanol coopared to the r.1ass of ethanol? I !ilean since the stoichiometric air/fuel ratio of ethanol is 9:1 compared to 6.5:1 for methanol, approxililate 1y 40% of the reduced cy1 i nder temperature E~ffect coul d be due to tile differences in the fuel mass as well as thei r di fferE~nces in 1 atent heat of evapora t ion. A: Certai n1y thilt is true. There is a di fference i II russ. agreeab 1y and when you are talking about stoichiometric mixtures, you definite11y have less ethanol than methanol in the cylinder. But the latent heats of vaporization are also distinctly different. X think both effects are there. Q: Jerry Panzer" Exxon Research. ~laybe missed something in what you said, but when you talked about the concentrati on of nitric acid in the exhaust, I was wondering whY it didn't peak a 1 itt1e lean of stoichirnnetric like nitrogen oxides do? A: These calculiltions \rt.' -:.t;::-:t.'l.::I..·,: :,' ",::":;:'1..'[ :t..·::..tin).: i:~ :.;earch .':- ,'pt:":::..it '\;):':l"':,i~ ::.,l~ '-":'!I.~:tl,-':'!~~ :-bl.· "':",'::;p:ett.."li ~crt.·t.·n.t:"'.....: ;'h~l~t.' :::,-::',--,l~\.''': :~ ~_t: .1~!Ji~ i':\..'':"> · ..... hi~h 'i:lhiJit .... ·('=·r.·~:'.t.: •. :~ :t.\,..':~ '; :~t~· ;~l .. 'rh.!~ ,-'D ::-;O!:'H..' ~!E"!':L:\~l):. "L'..:'.....\~ .. ·'-: : :',1:: ... ',.',1: :~.1;::, tht.' ;' ... lt~n :. :'.1. ,:' '>_·I..."~:-::l::~: .i ':,1 ,'1' _ .. 'r~t r.!.~ut\.'r :.~.\ ~:~i.::.;. ",:~,t:::t,:··:I..., .l::~r~~~it:.",,~ :- ..... :t..:':S :'r!\·\..'nt,-'!'y. ~-:tha ::.': :':t.':"!"':'~>'e. · ... ·;.::1 O::,lS,-'::r'.t.' h~lS .11r-\.,~tJ\' :'t.'\.'D 3.0...1 ;,::; ~t:!n~ t~~:'t.·J .:.:} .1ut .. 'r:l.,tivt' :-:t..~L":":;" I.'!. ':~u-i\")us _ i:~:~:::,: :',i~c .;'~':~ ' .. t~l"::~ ::~t.' .. : .. ·~r.:l:: i~)i: i :~' :-:!et::.~;l\"l-cl.."nt...iiui.!~~ iu .. :-:s ~ln(.,l ... ,th~r r~lat't!d -:~t.'tr..J.n\..~l ,ipplications qucslivI\S :~ay be in\'~sti l:att"'J~ Il.~)* ~.·he rt'sult$ to Jat~ havt! be~n t:lH;011rag,in~; h,-'\.,'cver, :jl'l!le !..~chll.i.\"-al problcI=-:S b.d\'ot! ....lcist.'no, ..-\:llon~~ tht:~se ;"roble1l1s are those as:::>(lci...lt~d · ... ·ith. ~:0rrLl$il.)n llf 7::tetal engine parts ..lnd JelctcriL1u$ ~if~~t.s ,,-'11 ?(."lya't'ric materials used in autlunotlve fuel sY::items_ This report summarizes the progress r1\.lt..ie ut> ttl this title ,.)f the project having th(" :1iitin vbjective of ;-\um.b~r;-{;;-p..:: .. r(>nthcscs dt.\si~natt~ references ;: ~ en\.1 n f p.a;>-e r. 371 C. F. Rodriguez and J. P. Cuellat', Jr. Southwest Research Institute identifying. ubtaining dnd evaluating com- ~ercially available fuel additives :hat ~ight be applicable to reduction or elimination uf engine and f'lel systet:l material Jeterioratic'n in ~etha~ol fuel blends. AlttlOUgh ie new vehicles it may b~ ~0ssible t\' use i:7lflr('lvcd :-:1.:ltt.'rials that ..lre not subiect t..., ,1tLIC~ ~v ::-:'t..,t.h<.!nt'I-~asi.. I i'.A T I O~ The ?cojcct was ,-'Organized into t\o.·\.) :nain parts: the screening task in .... 11lch six addi- tive.; "ere obtained and evaluated followed by the optimization task in which three additives (.~xhibiting some 3pparent pr('1tt!'ct ive effects .'cre further "valuated. The t"o tasks were iurther Jivided into subtasks as shown be 10"": TASK I - Initial screening tests were conducted with the si", additives in m<>thanol- gasoline blends. SCBTASK IA - Fuel blends were prepared containing l'ZI.ethanol • .::asoline. 2-butanol. and the six additives. Sl1f1TASK lB - ~etal corrosivity tests were conducted according to recrnmnendations of Jpplicable ASTM and ~ACE standards. Elastom~r and plastic compatibility tests and physical property deterl!!inatiotls were conducted accord- ing to the appropriate ASfM standards. SUBTASK [C - Results of the corrosivity and compatibil.lty tests were evaluated relative to results from baseline unleaded gasol.':'ne neat and blended with methanol. SUBTASK In - Three additives were chosen for further telit ing in the optimization task. TASK II .. The three additives chosen in the preceding task were formulated singly and in binary comb:lnations with methanol-gasoline blends for testing to determine if higher con- centrations or combinations of additives would produce the desired optimimum protective cond it ions. Sl!BTASK IIA - Fuel blends containing the additives chosen in subtask ID lJere prepared for further corrosivity and material compati- bility testing .. SUBTASK lIB - Corrosivity and compati- bility testing are being conducted with the materials and fuel blends formulations chosen in Task I. SUBTASK rIC - At the end of the test period the eff~,ctiveness of the three additive formulations in methanol fuel blends will be evaluated with respect to reference unleaded gasoline and :nethanol blends. EXPERI~IESTAL PROGRA.'1 The progl'am was divided into six 30-dav periods during \Jhich two 30-day periods ... ere required for corrosivity determinations. The materials compcltibility testing periods require shorter periods and were conveniently con- ducted during the corrosivity test periods. These two test periods began at approximately the one-third ... ·".~i~:-':",4~. :rt!..ltt!r "':'drt> · .. ·as td.;"en in ::::x:::.: :::t2 .::..:: ..... ,:~\..:::.:) .i:: ... : !: .. l::il.,lint- :n :'r..ier t:!at :~e ~,':'':::~t:'r ':'):':~t?:.!tr~iti.. .. 'n:s __ 'f _iJ.iir':":ts JiJ :10t "':'3;.l~\? :':t:: '".:att:f ': .... "' ~e?ardtt!. ~~r.~"::0~ '.-Gl{ROSIVI:Y - Tt!n ~~ta:s us~d in _·1:-:-~':"':. .... O:l:.'t.< t .,:.l':":i.:t?S$ stet.<, :t.·r:1~;d.:ltt..', ":.l:-;~ _:".':-', :-:.lSS, :-r .... :'n":Ct ::tdgnt:.siu::-: ..lnJ. ",:,oppt.'>r '~'t!~"t." ,:}t,~:::t.>":' :.:: :-:-::.r.:. ::'.,i. .... 'i-\. ":'-'Url.'ns~ S0-:-:"..!-::. ~'r~~~r~c : ':. :~S:~i:l~ jy ~astli:l~ :n ,i ~01dtil~ .~"'..::anil,.' :--.':vt.':;:: .. ;"' ..... lishin~ 'woo'ith ..1 :.:.~~ ~rit ..ljr3s:'ve ~ !~tht ~insi!l~ ~ittl ttl~ 0rg3nic ':> .. ':·:t.~:1':~ _l!h! .":r';~~1~. ,\::~!uugh ~~.ere ..lr~ :1\) ":;:.i::~:.J.r...: ~:\.'t::c.i'::. ~l..·"di:.i:':~ :",-'1' ".'r,::"vSi0n ~e::;~ :r:.g~ :.herc ..itt' !'t;'c,"rraacnJat l ... 'n~ \ 3-d) \o:hich ",,:cre :"l.,)110\~'t~d ... ·h,!rt..~\'~r .. lpplicabl~ to ~hese experiments. Each SptCblen ... as suspended half- ... av in ~50 ml test soiut1on cuntained in a i;lass :"ottle sealed ... i:h .... sere'" cap. This drt"..:lngeItlent ~a\'t.! ~-l fluid ':ol_":lc tl." spcci::ten :;urface area'·rat:lo vi ').35 :nl':=~. Each t>ottle ~1...'ntainetal ion effects. ,my effects of the fuel vapors (;oulJ !>t) observeJ vn the part .::o! each specinetl not i=ersed 1:1 soluti.::on. The bottles contJlining the tt;!${ speci111ens partiallv i:~rs.,d in the test $,)lutiuIlS were 319 ;:>laced in a constant temperature chamber main- tained at ~3·C fer a 3D-day period. In order to maintain a. nominally constant level of avail- able oxygen. the solutions were reaerated by sparging with compressed air at the halfvay mark of the test period. The solution corrosivity tests were con- ducted in Task II in the same manner except the number of metals was reduced to six. Zi~c vas aoparently not affected by exposure to th~ test !>olutions in Task I and was used as a confirma- tory control. The other metals: copper, brass. bronze. terneplate and magnesium were all apparently affected to some degree in Task I. XATERIAL COMPATIBILITY - Pol~~eric mate- rials for compatibility testing were chosen from the two maj0r classes of synthetic elastomers and plastics. in addition to a naturally occur- ring compound. These materials represent as broad a range of applic:itions and chemical types .is -:ould reasonably be tested ... ithin the scope "f the program. TIle twelve materials used in the compatibility tests are: 1. Sitrile (XBR) - high acrylonitrile elastomer. a butadiene-acrylonitrile copolymer" 3. b. cO. Xi' cile (SBR) - 1"",' acrvlonitri:e C:astoI:ler, ,1 ::· .• taJ':'l.;'nt:-.j-..:r~:: .... ~nitr~:t:' LOpO l;.:-raer. Fluor\.'>carbon elas'torner. a vinyliJenc fluor~de and hexafluoropropylene copolymer, Seoprene elastomer. a chluroprene (chlorobutadiene) ;>olymer. Epichlorohydrin e~ast0mer. a .:hlor...)- pr0pylene epoxide poh-r.ler, Fluorosilicon ~ldstomcrt ? !~uorinated silic0n cxide pol~~er • . ~Let,al resin, a .:npoly~er .... ,f .f f0~al Lind glyco 1, ?01ypropy!ene-high ~ensity~ 3 ?r~py ~ene ?i.."'1 1 yrner ~ ?0}yethyl~ne-high J~nsitYt dn ~thylene ~I,-) 1 ymer ~ ~ylon. ,1 polyanide :::ade :-r~~J i.~icar :' .. '1xylic .3(:id$ ~lnd ~:iar.";ine.s,, Perfluorocarbt.")n, -i :"u!ly f:uorinated 1 inar poly-mer. Clnd Cork gasket matel.'ial ",ade :n.>J:l .cork 0ak. ~h~s-c :1dt~ri.;ds, ... )btain~d .1$ sheets, ''':t:r~ Lul int,) coupons with a size C Jie and the ;>hysical prope;:ties of tensile strength. ultimate ~lon gation. \'olU1'!le svell. dir.lensions and hardness were Jetermined .... here apFI'opriate according tt' the ;>rovisions of the pertinent ASTI-I stan-· dards. \9-12) The Task II __ sting of these ~aterials was conduct .. >d in the same manner except that the number ,'f substances \las reduced to six. TIlese "lx ",aterials consisted oJf thr.ee elastoo~ers: flllOl'l1Carbon. nitrile-high aCr)'loni tri Ie and ~eoprene; tvo plastics: Sylori and perfluoro- carbon; and the cork gasket !!.Iatef'ial. TASK I RESt'LTS Results of exposure of test specimens im- mersed in bllmds containing the test additives were compared \lith control exposures. Control determinations consisted of the corresponding material specimens exposed to gaso line con- taining 0-20:: methanol and no test additives. All comparisons were :nade within a material group only. In no case were observations or rat~ngs made on one material compared with those made on another; the results =de an\' such comparisons difficult if not impossible in most instances. CORROSI\'lTY - ~lithin the first ... eek c'f the test the magnesium specimens immersed in ,he 20% ",ethanol solutions had completely disinte- grated. Only the specimen in the b lend ~,>n taining additive D re:na.ined intact for the Juration of the test as did those in solutiDns containing the lesser a.."'>Ounts of :nethanol. Brass, bronz", copper and ~erneplate exhibited visible effects-for the :::lOst ;,art coh)r changes-at the end of the 30"-day test ;'erh,c. The other metals had no detectable changes .inC neither did any of the ",etais in the ~as0:ine control solut.ions. Except :'('r ,-")c cas i ... :'n,a, 1 ~ ra.ndl.. ... r.11 .... ,-'c..:ur;:.-:-:~ ?its th~re ~dS no ~~~i~nce :~3: ?i::i~~ ~,-'u:~ ~e 0i any US(~ in assessing th~ extent 0f ,',-'r- rosion. T:lere was nL' :1casurable ..... eight ('~.J.ng~ on any of t~,(:, randomly select~d :netal test specimens.. ~:ven the ::tagaesium Cl..~Upl..lnS ' .. :hi...:h had been i=,:rsed in the 10:: ",ethanol :'lenJs apparently :leither lust :lOr bained ,1nV '.'eight. Changes in coloration were leit as the ~n:v apparent effect of currosive action 0f the ::letnanol-gasr>l:'ne blends. Assur!i:lg that :::e,;e ~ffects were corrosion related, :he t~st s~r~;'s were ranked by visual inspecti0n relative :~ :~~ control · ... ·ithin e...lch ::t€:thanol-l.."c'>nCentrat i ... ~n ~;.r('up. Ran~ing the brass :cst s:r:r)~ ::1 :~:.is ::tanner ri;:;ultt!d in the ic~10,",'in~ !'dt'..:"!~S :~i:':\;: CORROSIO~ I~HIBl T10~ :L-\''\K I:\C ~ethanol, ~nhibiti0n \'0 I ~ Best .... \ ... 1'.-.; ~ ----- ---------- 2.5 C K ~ ,-\ S :' 5.0 K C B D A - 10.0 D'~ B* K C ~ A 20.0 A* B* D* K F E C The cont 1'01 in each grt>up is deSignated "K". The asterisks dt's ignate distinct ly less corl"l'- sian noted on the specimens im!1lersed in these additive solutions as compared to the controls. These subjective evaluations indicated .:>nly additives Band D se~ to have any significant inhibitory effects on corrosion ,'f the brass and bronze specimens. :"iiatibilities between gasoline iuels ,lno ;1'_<:-"- ~eric fuel system materials, these te,:,.ts ·...:er~ conducted to ascertain that the canQi~ate additi\'es .;ould !'lot create any addit::"0nal -:I.1:n- pat1.bility ?roblems. The ?rDperties :;:easu:-ed ~J deternine co~patib~li~ies were tensi~c strength • .l:ti::late e100gation" ':clu:ne ::i ... ,,;e~~ .. J.nl: ~ardness fc!' the ~l.lst..J\:!ers. Ji:':':.(,'nsi....-~nai '::~lJ.r:Lt.. · .. ·as substit:..zted ~'l1r ',',."" ~ade .... 'tl t:-:e LC'r~ ,;asket ::lateria;. Chan~e :n ~cnsi:e ~trength :5 cx?ressc~ ?ercent :-eta':'neci aftt.~r .:..~(!rsion :'~l :'r:~t ~2::! t.!..)n coopart!'d t.,"1 the ·:.1:·je ~~f0re ::7"J~t:r;':'~l-':--,. :\('...:.,)rdin~ : . ..: t~t: ;-,ass :ri:,,-r:l1 n :',,1' t:':,i~'~"--::"'r;-~ .cJ:1::,.i:~ :;trt':1g~:1'" t.>;~~",::::~·r\,.:~: ... t:::'1:1 .il'!~ :' : ....... :-,'-' sili-:one :ai.!.ec. at ~l ... : ..:....:-ncentrati .... 'ns _'f -::~t~:'I ~ol and XBR-io~ acrvIJnitri:~ ~dS ~ar~inal. ~xamination · ..... f the tabulat.:d r~su:ts \ .... :. t~"iot= !.t"l1sile :;t:'t::ngth ;.}eas ...... !""et'lcr.ts jee:~cJ :~' ::~c.:'':,t:t: t~lat the ,l(iciti~'e$ had !'h~it~lt:J>r .i :'ene:" l...: ~~l. ~ :-'.\:. .1 Jt=tr':'=cI1ta: '~ffect :':1 -.iny i:15t..lnC~ :--ut :.:::~ ... ·as :1l.. ... t !'"eaci ly apparent. .sin~e ~: ~cel':lcd ::;a.t :!\~ t'~r~cnt :'t,':"::-:!. .,':-' ~as \iccr~.lS!~~ dS a fuc(:i ... ·~ ~~ :~!c ~e:h~~. : "':L':lCentrat':''':'f! .. ...i~l .'t ::It,'. !"csul'_s '.;It:-:::"! (.',h"~: ~~t~rid: ~r~-up ~ere ~0~J3:!z~d ~::~ ~cS?~(: t ::;e ...:: ... )rr~sp...:·":'".!.ding ·:.ll~t..:' ::-. ~rr!~t."~l"':t'~~ .~d-, : :'::c, :-~t.: :: ... 'r.":.1.::...:~J ·;.a:".h.~.s :.·r ::~~ -;i:.~ ~i.J ... ::.'.~':~:::- ~lthitl ~ ~~:~an0~-~~':lc~~trJ:i\'n ~r~'up ~~r~ ~i\'cragcd ,inc ...:: ... ).t!r.lre~i ~ ... : :~'L" ~:l'ntr...-':-; IS :-::: .. :\,.,:' ~n Fi~~ ! ~i:h til~ ~,)!l:r~: r~sul~ ~~s~~~a:e;: ~:; .. ~" ,inti :~.c test ,i\:~r.lf:t:' ::"y ":-." ::-: ::~,.: t.:'xa!":1p:e sh..::-... t'n f ... '1r epich !0r·,~byJ I' i:; : :H?' ~~ ,i:1": ~ ~alu~s dr~ ~ss~nti.l:l~ i~enti~~: sin(~ :n ~:: C~h;-eS ~he yariability ~:' :.~c :- · .... ~~l:es ~t .. !".::-:t.:'...: ::''( t'i::~~r ::":i? !'"an~\.> ,'r ~:.l!KLIL! "":;"~:.'" includes the correspunding ~alu~ :i K. Tht. ... st: results \.i·ere ~sst.:'nti31 =.\" r::t! ~...i.r.:e :' ... 'r the other five elastl..")mers t~xcept ~~at. :~~ :0::;'::; ... -.i tensil.~ str~ngth ..... as apprL-.xi:-:l .. itei.\" cqu.al !· ....... r ,\11 four :~thanol coocenr,ati,):ls. ,)nh' with the fluor')carbon did the re!.ent h'n ~rest:'nc ::I II T z ... rn T ~ 60 ... J ~ ,.. ;:: S 50 ... or. L_~Ol.m 0.0 2.5 5.0 10.0 21).0 METHANOL COrfCENTIlATIOIll. VOLUME PERCefn :--!~;t'RE ~" ::F~~~:::~()~ t)r :-L~SIL[ ~T!~:~:~CTH ?EL\7I',T 7(\ ~·::L~:..\nED ·::ASI):. !~:[ :::\.'n~::lt. i,'~ :':"!l'.l.surt.'~ents ~lr~ ~11sl' expressed as ;-,erct.:'nt I"t?'tl.'nt :_'r. cl!-t.~r i:-~!I;-:e:-si(1:1 in test s0!uticn. Onlv ~;11~hll~r,'hvdrin ~aileli to ~~ct the ~.1~~ ..::r-i teri,:>r.. ":-;hal t not :\.lSt.~ ;'ll ' re than tensi:~ str~ngttl. Th~ resLl~s ~rl'D tile epiC~l,)r('lh~'drin ... !.:.It...l .. ift: sho\~ll. in FIg . ..::. to ;E 80 o ;:: z 70 o .... '" ~.o _ ", ;r Difficulties in cutting the cork test specimens made it possible to accuratelv oea- sure only the thickness of the coupons," There was no change in this dimension d~tected after imlnersiL'l1 in the test $olutiC'llS. PROJECT STATt:S As reported here. Task I, Screening, has been completed and Task n. Optimization is unden..ay and near completion. The Task I cor- rosion and compatibility tests "ere completed on a test matri.x including six additives. ten metals. six elastomers. five plastics. and cork gasket material in fuels containing four con- centration levels of methanol in unleaded gasoline. The evaluation of Task I results led to reduction of the Task II experime~tal ~atrix to three additives used singly and in combina- tion. six metals. three elastomers. two plastics and cork gasket material in fuels containing three methanol concentration levels. The same corrosion and compatibility tests conducted in Task I were used in Task II. The Task II test period is ending at this time; results of the evaluation will be published i.n the final report of the project. REFERENCES 1. "Progrn :Jf Pitting Corrosinn," ASTM G·'6-76. Test :-!etho~, "Antirust Properties of Petrc- ~eum Products Pipeline Cargoes," :-;ACE Standard TIl-OJ-I:> \1976 Revision). 8. General ~otors Cor;>oration, "Cnleaded ';.1S,:- hol," Engineering Standards -:;M6161-~ aLe: ,;M6162-M, ~;o\'ember :9-:-9, Section 3. Standard T~st ~ethcd !~r "Rubber Proper~:< ::1 Tension," ASP.-I :: .:.::-tlO. :0. 5tandard Test '1eth0c :C'r "Rubber Pr.':",-r-: ,.- Effect vf Liquids. u A~t J :'-;l-;~. Standar"': Test :-1(:thC'J :.:.'r "TenSile ?r .. ~;'t!r~:t· ,J! Plastics," ASP.-l =-' 1)38-80. Standard 7"est ~eth0C :or IIRubbt:?r ?r-~';-,t.."!":" ~)ur(lm(.·ter Hardness." :\SD! D ":~':'O-81. The ?r(~~ect i:; :,eiz:~ .::'nductt:~ ~,~ :)t")E _,--"ntract ~\\~. JC\3-'?S-: · ... ·:.t~ ~r. -.. :e(lrge ~~. ?r- ':(. ·: ..... s....;-:.e· .... i~, .... I .. :r·:i.~~ .i~; ?!'" .t,. • ....:: ~~ • .1ndt:t:r. ;-r,-'_'~ct is .J ;'~l.rt __ ': :~'.t.' ,-=..; ..... p ~t"l:~k!. :'t.·r~·~·:··-t.. =y :~e Stirling Engine anC Alternati~e ~l:~:~ ?~0~ect Office I Energy Jir~=t0rat~. :.eRC) f'r :~t.> uffic€: ... "If \·chiL~t..' .i:"}(i ~:l~ine R\~.i). ll:-· ::'," ·:.: ... ':!ser~·ativn .1n~ Renewa:-:~ E.ner~y .1:' ~~;t: Jepart~~nt ~f ~npr£y. QUESTION AND ANS;/U ?ERIOD Q: Jerry Panzer, Exxon Research. I have two Questions, but let's take them one at a time. How did you decide which alloys and elastomer formulations to select for testing of each of the particular generiC gl'OUpS that you did select? A: Most of these choices were based on the materials that are used currently and in d couple of cases, such as the fluorocarbons, those that are projected to be used to gain lUore extensi \'e use in fi e 1 d systems as we know theiYI now, Q: You mean the auto companies told you which elastomers they use in their cars? A: Nu sir. 1'bhl1'~' Ii "'~t «, r.oIoloa. Slal • .., ... :. .. 1>4 o~>-"",. oil· ,~ i8 POP<"" or 4 ..... ~ ... m> t~ s"tIl",·. an4 """ hl!l 1 •• ~lty. 801 SAl':',; l>4"'ow.:. tl", r ...... ~ !l><.." t>!ln"~ I'll SAE ro, "nlf""i!I ttl'1l3..Il oM (Offft&t ",ru ... 1~14 ... m. u.. rU"Ct it II Iol"Il>llMrlln SAE T"'_L~. I' ... p~ 1<> p~ "'~'I'~ II> r..a ... ~,..rt. <;<)e,-ie'lCE- and '1'01:1 whdtever other SOLlr-ce, J<'PJVdilable. ,oe consult wi trl C.eol'ge 'lere 0'1 ~hcse thi'1g5 and we talk to as 'Hny ;Jeop;e as \'Ie ;,ossi~lj ..:an in the aut~notive aredS. Q: The second qut's t i on d€a 1 s wi th t'!e ft;e 1 fOt'f.luhtions. ! notice that the ,·~t;;:' :f methaool to cosol vent was considera~ly !1igher than in the blends which are Cllrt'ently being mar\;eted c~;raercialh ,;r are ap~)roved by EPA . .\re y.:-u planning ~o take a look at those kinds of cootlindtbns in any of your future work? A: fie haven't gotten that far jet. """"""" utltd", "" mbli>ul ,....... 10 ""' ~oeo4 r"" ,... ... ,,"'Iiw <>t publl_ ~t •• a )00 __ """,,,,1 01 • ~_~ilI't "" s..a"IlIBY. En_", .t\CtI<\I5 ....... SJ\L End of Document

Proceedings of the 20th Automotive Technology Development Contractors' Coordination Meeting

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