In the systems under consideration, refrigerant is evaporated in a solar collector and condensed in thermal storage for space or water heating located within the building at a level below that of the collector. Condensed liquid is lifted to an accumulator above the collector by the vapor pressure generated in the collector. Tests of two systems are described, and it is concluded that one of these systems offers distinct advantages

Hedstrom, J.C.

Neeper, D.A.

UNT Digital Library

A major purpose OT tne IIecnnl-cal Information Center is to providethe broadest dissemination possi-ble of information contained inDOE’S Research and DevelopmentReports to business, industry, theacademic community, and federal,state and local governments.Although a small portion of thisreport is not reproducible, it isbeing made available to expeditethe availability of information on theresearch discussed herein.i1LA-UR -85-2703LA-uR--$5-27O3DE85 015736TITLE PASSIVE VAPOR TRANSPORT SOLAR HEATING SYSTEMSAUTHOR(S) James C. Hedstrom and Donald A. NeeperSUBMITTED TO Solar ’85 ConferenceRaleigh North CarolinaOctober 15-20DISCLAIMERThlsrapm wu~dusn ~ntdwk~d bymn~dtk Unitd St*ta(lowmmnnt. Noitbar ths Unkad Stota ClwwmrnMt nwouy~tt.ord,~~nydthohem- rmka my wmoaty,expaf lmpIbd, arwunws~yb@ Ilobilllyoc raped-Wty kwllw-mey,-~ofumfulwofq( lnfwnrmlbn,n~raluqpdud,w_~m~181bst humwudd MMiord~fMiValCly owned rights, Rcfer-erm W @wcpMca MIInrercid ~uct, ~x mwiw by trodanmne, trorknmrk,monufodu~, or otbemlm * not ~rily mmtltum 01 Imply k omkwnont, romm.rrrdsthnr, w fmriq by the Udtd Smta Owommait ar SO,VWKY Oweof, The viowtand @moaI d ●rtbm em- hurdn da M rrewmdly stale or rdkct Itraoo d theUnhal SW= Oovommcml w ●ry ~ tkrwf.~,~~!kk)~~~ LosA,a..s,.e.M i ,Los Alamo. National LaboratoryI(MMOCJOnd-Wind -.-., -. . . ..- w .—. — %?ASSWE V- WSWUT !30LAD HEATING SYSTS?L!5Jut C. RadatromDonald A. IJaeparm .J577Los Alms National LaboratoryLao Alma. NM 07345AMTRACTIn tlm 8YSWS undr consldaration, rcfri -gorant is evaporated in 4 solar colloctormd cm~nmd fn WMrmal st.cmgo for spacoor bat.or heating laatad within the build-ing at a level bolm that of the coil K-tor. Con&nsti liquid is liftad ta anaccmulatm abovo tha colloctor by thevapor prcssurs gomrated in the colloctor.Tests of tuo syttas sre described, and itis concluded Vi&t one of thew systusoffers distinct advmt.ages.1. lNTRQCUJCTIQNOur ~nvestigatlon of vapor transport wasstimulated by a perceived rmed for 8ystaswith particular charactiristlc$, BriefSystm studios [1,2J indicati that thesolar roswm on th~ envolopo of a build-ing is In principle 4*qu*t4 to mot thehinting nods ●ven ~n tovore climtes ofthe US, b-t for this r~sourco to Mexploitd the soltr cnargy systms muldn~ad w havt hi@Qr @f flc\oncy, or toutillze mre of tit. envelope (including theroof) for collection, or both. Mostprcsant passive heating syttm8 delivermcontrol led heGt to tha rm or ZOMdirectly behind the south ml 1 of thobuilding, The floor plan of the buildingmy not alwt t pemit mloquati heat dlstriJbutlon to o ,or zonm by natural convK -tion, md many ●isting buildings do nothava c Wi table southern @xposure fordirect gain, thermal storagt wall , or cun-space tystmt, U. ttmrcfore smght anitislized passlvs syttm that would a)provtrh superior efflcimcy by ■lntaininga 1- absorber ~oratura and by dlotiaction that prevents haat loss at night;b) provi+ dcwmrd trantport of hott, thu$●nabling olwatd surfacau of the buildingto ba usml for colloctim; c) providapaliive dlttribution of heat to all fotwsof W building ragardlosa of MO buildingarchltacture, md d) Qh@b18 O- controlof haat dtlivc~--at l~ast masonal ahut -Off. As ex~lifid by a heat plpc, avapor systim can trantport large munts ofpmr thrwgh a s11 pl~ across severaltent of fw)t with Ion qiaturt drnp, andcan prohibit trmport in the revarsed~rrction--thus displaying themal diodeaction. If mltipl~ condnsers are con-mctod in parallel and Iocatad in tnomalstora~ llitt in different zones of thebulldlng k~ shwn In Fig. 1, the vapor willprcforentially con~nse in the coltistuntt, thus tmding to provido uniformt~erature thrwghout the building.Because all trantport occurs via mallpipes, tha building archltacture is■inimally d~sruptod by the Mating systm.seasonal shutoff (or Qvtn mrc frequentcontrol) can be aChlQWd by a tinglevalvq. W. notod that vapor systis therebyoffer omortunity for achi~ving theidaaliz~ systm characteristics mntioned00W , if mans could bo found to providedcmward transport--which Implltt passivereturn of continsatc u~ard to the colloc-tor. Me have thcrcforo exsmincd tm self -pmping tysMm8 as &scribad below. In allof cur cxporimnts, M have used Refri-gorcnt-11 as the uorklng fluld, ●lthough inprlncfplo any fluid with witable dansicy,vapor pr~swrt, and lat8nt mat oi”ld beusad ,2. THE SINGLE-ACCUMULATOR SYSTW-lh~ slnglo-acclmlator system is shown inFig, 2. Earlier publishtd wrk on thissystM and on relatid systsm is r~viowedin Rofs. 3-6, and titails of wr txporl-Unts am given in Rcf, 3, In this systvm,tlw condennar flllo ufth continscd liquiduntil tho reduct{on in haat transfar causesa wf!iclont ris~ In coll~ctor toqcratl’refor th~ vapor presaura to l~ft liquid frmtho continscr to tha acctmlator. Uhon thsacc~lator 18 full, valve V opens to●qualizo tha prcssurt In tht accwlatorand colloctor, and the accm,ilatid liquiddrmfns into the collactor. Ntmn theaccwlator Ik naarly mpty, V C1OS*S andtha opwatlng cycle b+gin$ a~in. For● trl~tal cotwmicnm, m U* aYso onoid valva. but w have also usul apassive flost V*l VQ with Success. Usconfigured a s.psco-hwting t.mt CO1l with~ coll,ctor m W rmf, mquiti~ 17feet of llquid llft, u sh- in Fig. 3.The Sy3t9 Op.Utt.d tS ●~CtUi, w!th aself-mgulitlng liquid 10VC1 In Wcondns.cr. TM pmssum difformco bwtmnti colltctor md UM accumulator drlngW p~ing pha= of oporatim was oaactlyat mqulrsd for liquid II ft.m/ I DOWNWARD TRANSPORT/ 1 MULTIPLE ZONES——I [----- ‘*f& DOiOCRIN 1!!9$&k -----——VAPOR-----:- L 10 U ID&T,11L—#1JrFig, 3, Di@grm of the single-tccmulator$ysta arranged tnr space heatingof w mtdoor test cell.liqrld and becwse t.. @rwrw for con&n-SIIW UM volw of vtpor tit dl splacesllqld wst also k ~Vti frw Vmcabml~tor drln each cycle.!Tho t~r-tcwlt ftiturol of lg. 5 are that Sysmperfofmnco is q! ti S.nSlt~Ve to ~ and‘1, and that axlmm P.8rfomnco :sa hlovod for ~ gms~r tlwnOptimal desi~ rwquires thxt % accwla -tor hsvo ts little Mat capaclv ●nd freellquld wrfaco M pessible, ●nd Wt ●de-WM oxtern:l CW1 tng h providad.Id@&lly, qP of •~roxiutilv ~~ should b4ttUi Mble, but M4r-Opti U\ ●xt.@rnalcoolinB alght rcqulrt a Xr*ture-mgulat.ed Mat slti L3,4J. Frm ourin~gratid Mf ly masu~nts of systamperfo~nce, W Qstimstml that3of ourpips acc~lators was approxim ly 30%,and that this caumd OXCQSSIVQ col lector~o~ures. ~~1~ fnV@stf~ti~ ~cC~Uld-tor *sign, m concolvd t conflgurttlon oftm tccmlttors thtt requires no ●xt9rn41cooling,3. THE TUO-AKUMI.ILATI)R SY$TE~In the sy$tem of Fig, 6, both ●cc~ulatorstnd 611 plplng arc ~nsultt#d to pr~vontenergy oxchtn~ wi tn the surroundl rigs. Thecoll~ctor tilivers v~wr to Uia top of thel-r accmulat4r, fria ti~ch tht vaporptssos u~ard threwrthe opm float valveto the continser. on~nsed 1 iauid drainsby grtvity through a chock val v; into thelowr tcc~ldtor, Uhen the l-r accwlttor is flllod, the float valve closei.Tht tmporature of tha CO1 lcctorFig. 4,1n-nb?la — —0060402’0mi!e[.’.”?*,,, r ‘ ,#, # ##1,11,,, l,@I 8,,11” I1,’111l“IIII- .—!.0 I00 150 200 250 300 2Olnc, Btuzft2z11bDifference between the temperatures of collector outl?- I .1 tIIPtop of therml storage, tis a functton of instantaneous tl,~l]llolon,for three accunnllators with diff?rent heat lossesFig. 5. Mltverod fraction of base-caseenerw yield as a function of lossratio for t ty ical collector.Ylns Iation is W Btu(ft~h “F)-l, $tiraetaper6tureis 03”!, *lentt~orature is 32”F, md theliquid CO1- !S llftmi by a 2U”Fdifference in sstur~tion tWcra-ture.&nd of the frm surface of the liquid inzhe l~r accmlttor rims until the vaporpressurt is sufficient to lift Iiquld intothe upper accumulator. TIW ~wctura andpre$sure of the u~ur accumulator rmstnclose to those of tho cm&ns8r bactuse ofthe untntirrupwd vtpor link ht~n thaset- c~onents, Mm MO l-r accumulatoris n~r y mpty, the float valve opens.The tmperatur~s of the collector snd lmaraccumulator rapidly fall to th~t of tho.ontinsor b~ause of the rorwad vaporconmctlon, Thus, tho th~tnal cn~rgystored by the ~olloctor &nd acquired by thoIouer accumulator dring the p~ing phaseof opera tton is trmsfcrmd to thcondenser as useful heat.Thls systm hm several advmtigas ovar thQslnglt-accmulator $Y8-. 1 ) During thomajor oortton of tha c~lo, th9 t~crtureof tno colloctor 1s kept C1OM to timt ofthe tlwmtl stirage, *or*as in tho single-occmlator tystm the colloctor ~cra-tum Is aluayt ●lovated by St least thtmount rwqul red to prtico liquid li ftuole!t *Q acctul~tor 18 coo!od to Jt~wature bolm that of stora~. 21 Nocltarnal coollng of tho accmlator fsr9quird, *1 Wnating W Qs.tr-tipmrbnca of tystm ●fficionv on theeffoctivc h-t cQpaclv and cooling rata ofthe accmulstor, 3) In prlncipla, noFig. 6. Dlagra of W ti-accwlatorSystn.oner~ is lost frm th9 system--allcollcctid emrgy is tilivorsd to theco~~nser, 4) The ccndenser should alwaysbe dry, ●nabl In W condsnsw trca to be$as large ts d8t A for hat trmsfor. Thesinglo-acc-later systu required thecon~nser to kM partially floo~d. 5)Except during thQ p~in phase of the!cycl. , liquid contlntmu L y drains fr~ theu~cr acc-lstor into the col loctor, thusktipl~g the colltctor full of liquid.W Wttid tho tw-accwlator systeu withan intir apparatus that has c cylindrical ,oloctrically hmt8d, vartical boiler ofapproxlmtily tht M- mtal MSS and11 Id volum as a colltctor plata of 22.4Pft arm, The cmdtnsor Is a 50-ft CO11of co~or tubfn!’0.626 irI, IX), 0,035 in.uall , l~rmd n an Uninsulaud bcrrcl ofwtir. li~id lift it a~mximtily 15 ft.Figura 7 mw$ ~raturet, praosuro$, andflo9 rata masured at spproximtily 20 s~ntimals d rln1152 Btu (ft~h”F!-~~::t~i:~l!:dto W bollor, .hich is IWrcafter referredto to tlta collrctorm tiring * ~ingphasg, tit. collsct.or xrature rtsoo mrethan Wcssary to rovida s~ttc liquid1 i ft, and ceums J o flou rate to rls~cWlttnWWly. Prwsbly, tha tratioffMtmn ‘do &rat~on of ~lng phtsc andtho ●acur810n of CO1 loctor tqtoraturocould ba optlsl WI as a function of thodiamter and length of W l$ft.ed lfqufdCol m, After tho fl~t valve opens(Indlcawd In Ftg, 7 by W shwp ~k ofcol loctor pressure), tho ~raturer ofthe COI loctor and of ttM continsor inl@tL_—_L—L——L_J-’ tFig. 7. T~oraturas, pressur~s, and flmra~ of the tuo-tccwllatir SYSMwith 1 kU of ●lectrlcal pcmrcrcu~li~d ta the boiler.becw nearly equal, md eventually bacmaapproximtiiy 8*F grtater than thotnptr~tumof me -W, indicating thatthl~ Is the Wperature drop required forhoot dran8for tcros~ this particularcmtins~r at this pmer level. The gratialticrome of col!octor hnd co.nanstrt8mperaturot that beglnt amroxlmataly onemlmte after tho valv8 op]ns MY bt anartifice &Io to hmt sb?red in the plu~lng(uhlch was urmactsa.arily Msslve). Theintecral of tho flmv rate fndicatis thatapproximately 10.6 lb of liquid is liftedeach CYCIQ. Vapor f)m of thll m nitudafwould corr~tpond to approximstoly SW U oflatmt hat transport, In contrast to the1~ U supplied to W bollor. Thtslndicat8s that at this pouw level the flowMpSratOr (shan to the rl~ht of Usecollector In F19. 6) is mt capletily●ffactl we, and s- liquid is being carriedInto the lwer accumulator with the vaporflon.“’!r: 8 1’-s ‘“w *en ‘w u[76 Btu(ft h F)- 1 is supplied to thecollector. The excursion of the collectort.eapertture and the temperature drop acrossthe condnser to W water are less thanthose of Fig. 7, and the cycle tlm 1slonger, as expucted. The Integral of theflou rtte corresponds to approximately 450N of latent heat tranroort, uh:ch leads usto conclude that no liquid is entrainedsIth the vapor flcnv, m? Utat 50 H is lostthrough toe insulation of the boiler andother c~ononts.●■la..tDmmnm Iml I=!=* IFtg, P. Temperatures, pressure~, and flowrQh of the two-accwlator sjstmwith 5@ U of ●lcctrlial powersuppl iad to the boiler,Figure 9 shas U’be ~surfd minl~ snd thetvera~ ~rature dl ffcmnces betueencolltctor md stira~ as a fwsctlon ofpcuer. TIM miniw.m ~wature dl fforencefs * b the p~rtl~s of the particularcm~nser Md Is proportional to p-r, ●sexpectsd. Thg ●verage txqwaturadi ffcreme 1s appropriate for estlmtim ofcollectir ~rature in system studies.US179 the data of Fig. 9. us prbdlcted thatthe tm-acc~lator vapor systi mul d givethe w tnnual ●ntrw ylel ~ as midali zed pmspd-uatar dralnback SYSW ini hyfirid s~ce heating application [6].Fig, 9. Kasured elevatlon of collectort~orature above storagetemperature as a fmction ofsimulated collocted energy for thetm-accwlatir SYSM.FIgUrS 10 shiny ● mdified version of thesystem In filch the liquid 1QV81 of theupper accumulator is controlld. Thi Sversion mul d assure that the u~ertccmulator almys recaivos llquid uhanneeded, mklng operation Insensltl v@ M thesystm volm and to the total mount ofmrking fluid in the syttm. This mdifiedversion has b-n constructed, but not yettnstid.4. CONCLUS1OHSHe conclude that ptssi vc dwnward thermaltransport is possible for both space andwatir heating. The tm-tawl ator SYSKprovides Its OWI cooling internally for thesol f-p~plng mchmism, and m concludethat it is auperlor to the single-accmlabr systam.TM)KCUURTWW TRfMFWlSYSTfHTOP CONTROLFig. 10. Diagram of a mdi flcation of tiIetm-accmulator svsta with level5.1.2.3.4,5.6,control at the ufier acc~ldt,or.REFERENCESDonald A. Meper and Robert D.McFarland, “S- Potential Benefits ofFund~ntal Research for the ?asslveSolar Heating and Cooling ofBul 1 dings, ” Los Al ams Nttl onalLaboratory report LA-9425-M ( 1982).D. A. Wper, “1-pacts of ResearchEfforts on N- and ExistingBuildings, ” presented at theDapartmnt of Energy conference,‘Soltr Buildings, ” Washington, DC(Rsrch 1995).J-s C. Nedstrm and Donal d A.Naaper, “Vapor phase H@~t TransportSysms. ” Los Alams NationalLaboratory report (in print).krsald A. Neepar, “Theory of a PassiveVapor Transport Haati ng Systm, ”w.btaltted to Solar Ener~,6. DS Beni and R. Friesen, “Passive-rd Mat Transport. Experimental~8ult8 of a Technical Unit, ” Solarfnorgy~, 127 (1985).Donald A. Neeper and Janes C.khdstrm, “A Sel f-pumping Vapor Systemfor Hybrid Space Heating, ” preswntedat the 1985 congress of theinternational Solar F,nergy Society,bntraal (June 1985),

Passive vapor transport solar heating systems

https://digital.library.unt.edu/ark:/67531/metadc1066623/m2/1/high_res_d/5451797.pdf

Passive vapor transport solar heating systems

Abstract

Similar works

Full text

Available Versions

UNT Digital Library