In 1985, the Gas Research Institute (GRI)
initiated a program with Tecogen, Inc., to develop
a nominal 150-ton gas-fueled engine-driven water
chiller for commercial buildings. The packaged
system has been designed, fabricated, and operated
satisfactorily in the laboratory and in a 450-bed
hospital. The engine chiller has been redesigned
to improve performance, increase capacity, and
reduce the footprint, and is undergoing field
tests at seven sites to verify performance and
reliability

Lindsay, B. B.

English

Texas A&amp;M Repository

GAS-FUELED ENGINE-DRIVEN AIR CONDITIONING SYSTEMS FOR COMMERCIAL BUILDINGS BRUCE B. LINDSAY Pro jec t  Manager, Space Conditioning Gas Research I n s t i t u t e  INTRODUCTION -- - In 1985, the Gas Research I n s t i t u t e  (GRI) i n i t i a t e d  a  program with Tecogen, Inc.. t o  develop a  nominal 150-ton gas-f ueled engine-driven water c h l l l e r  f o r  commercial bui ldings.  The packaged system has been designed,  f a b r i c a t e d ,  and operated s a t i s f a c t o r i l y  i n  the l abora tory  and i n  a  450-bed h o s p i t a l .  The engine c h i l l e r  has been redesigned t o  improve performance, increase  capac i ty ,  and reducc the f o o t p r i n t ,  and is undergoing f i e l d  t e s t s  a t  seven s i t e s  to  v e r i f y  perfonnance a?d r e l i a b i l i t y .  COMMERCIAL COOLING MARKET In 1967, t h e  commercial market  purchased approximately 83,600 u n i t s  with coo l ing  c a p a c i t i e s  g rea te r  than 5  tons. Of t h a t ,  1 ,601 absorpt ion cool ing systems were s o l d  with a  t o t a l  capac i ty  of  528,000 tons,  represen t ing  27.6 percent of t h e  t o t a l  market. In 1984, near ly  134,000 u n i t s  were purchased, but only 82 absorpt ion machines, 27,100 tons,  were so ld .  Gas cool ing represented only 0.8 percant of the  market. Several  f a c t o r s  can be c r e d i t e d  f o r  t h i s  s i g n i f i c a n t  l o s s  t o  the n a t u r a l  gas  indus t ry :  E l e c t r i c  p r ices  decl ined i n  r e a l  d o l l a r s .  The performance of  electr ic-motor  d r iven  vapor compres- s ion cooling systems improved and the  equipment p r ices  decreased. Gas c o s t s  esca la ted  rap id ly  and suppl ies  were assumed t o  be inadequate.  Mainte- nance c o s t s  f o r  e l e c t r i c  systems were low and r e l i a b i l i t y  good. In recent  years ,  these  t rends  have begun t o  reverse.  E l e c t r i c  p r i c e s  have esca la ted  r a p i d l y  a s  cap i ta l - in tens ive  nuclear  power p l a n t s  have been added t o  t h e  u t i l i t y  r a t e  bas?. These increases  have been shouldered primari ly  by the  commercial bu i ld ing  segment, which has l i t t l e  p o l i t i c a l  o r  economic recourse. The u t i l i t i e s ,  faced with h o s t i l e  regu la tory  review and permit- t ing  procedures, a r e  unwil l ing t o  i n v e s t  i n  new p lan t  cons t ruc t ion .  Demand may exceed genera t ing  capaci ty i n  many a reas  of the country and necessi-  t a t e  brow-outs  o r  cur ta i lment .  Gas c o s t s ,  on the  o ther  hand, have s t a b i l i z e d  and even decreased f o r  c e r t a i n  regions.  Gas supply i s  now s u f f i c i e n t  i n t o  the next century a t  reasonable costs .  The commercial market is  c l e a r l y  posi t ioned t o  consider gas cool ing a s  a  v i a b l e  a l t e r n a t i v e .  Direct-f i red absorp t ion  c h i l l e r / h e a t e r  s y s t m s  have made s i g n i f i c a n t  in-roads i n t o  t h e  commercial market. These Japanese systems a r e  near ly  40 percent  more e f f i c i e n t  than t h e i r  s ingle-eff  e c t  predecessors. Unf o re  unately , t h e  tumultuous fore ign  exchange m a r k  t has placed these  u n i t s  a t  a  severe  disadvantage. The high f i r s t  c o s t  of absorp t ion  systems can only be j u s t i f i e d  i n  those regions of t h e  United S t a t e s  with extremely high e l e c t r i c  r a t e s .  ENGINE-DRIVEN COOLING SYSTEMS Absorption i s  not the only gas-f i red a i r  condit ioning op t ion .  A gas-fueled engine can d r i v e  a  r e f r i g e r a t i o n  compressor, rep lac ing  an e l e c t r i c  motor, and achieve t h e  same performance per s h a f t  horsepower. The gas engine has an e f f i c i e n c y  of 30 percent  (HHV), which is  cotnpar- a b l e  t o  the e f f i c i e n c y  of an e l e c t r i c  generat ion p l a n t .  The engine c h i l l e r  should achieve a c o e f f i c i e n t  of performance (COP) of 1.7, a  70 percent  improvement over d i r e c t - f i r e d  absorpt ion c h i l l e r s .  Addi t iona l ly ,  t h e  engine c h i l l e r  can leverage the  advances i n  e l e c t r i c  c h i l l e r  technol- ogy t o  ob ta in  a  vs ry  c m p e t l t i v e  f i r s t  c o s t .  Gas engine-driven cool ing  systems were very popular i n  t h e  e a r l y  S i x t i e s .  Major engine manu- f a c t u r e r s ,  such a s  C a t e r p i l l a r ,  Waukesha, and Continental  , marketed t h e i r  products t o  numerous packagers, such a s  Ready Power, Gascool, and Comf ortTemp. Approximately 2,000 engine-driven sys  tems were sold t o  c o m e r c i a l  and i n d u s t r i a l  f i rms.  Nearly 25 y e a r s  l a t e r ,  many of those systems a r e  s t i l l  opera t ing .  These systems demon- s t r a t e d  high r e l i a b i l i t y  when properly maintained. However, poor maintenance o f t e n  r e s u l t e d  i n  eatas-  t r o p h i c  f a i l u r e  and system removal. I n  1985, t h e  Gas Research I n s t i t u t e  (GII) i n i t i a t e d  a  program with Tecogen, Inc.  , t o  develop a  nominal 150-ton gas-fueled engine-driven water c h i l l e r  f o r  commercial bu i ld ings .  The engine c h i l l e r  would c a p i t a l i z e  on Tecogen's experience i n  packaged cogenerat ion systems and u t i l i z e  t h e  454-cubic-inch Chevrolet engine used i n  t h e i r  bes t - s e l l i n g  60-kW package. Tine mass-produced automotive engine has v e r y  low c o s t  and e x c e l l e n t  d u r a b i l i t y .  Severa l  engines have exceeded 20,000 hours  of opera t ion .  Waste hea t  from t h e  zngine jacke t  and exhaust can be recovered a s  hot  water f o r  pool h e a t i n g ,  domestic water h e a t i n g ,  and space heat ing.  The hot  water can a l s o  d r i v e  an op t iona l  absorp t ion  c h i l l e r  t o  produce a  supplemental 30-35 tons of cool ing.  The engine c h i l l e r  has  been designed and t e s t e d  with s e v e r a l  d i f f e r e n t  components. The c u r r e n t  system i s  comprised of the  Chevrolet engine,  a  Howden screw compressor, advanced microprocessor c o n t r o l s ,  an o i l  s e p a r a t o r ,  an economizer, and condenser and evaporator  bundles. The engine c h i l l e r  h a s  produced 142 tons  of ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987cooling a t  a  c o e f f i c i e n t  of performance (COP) of 1.4 a t  ARI f u l l  load condit ions.  The c h i l l e r  i s  r a t e 3  a t  an engine speed of 2920 r p  and output  of 147 horsepower. The engine can vary i t s  s p e d  from 1000 rpm t o  3300 rpm t o  meet varying load condit ions.  The var iab le  speed operat ion g r e a t l y  improves t h e  part-load performance of the c h i l l e r  and permits the  c h i l l e r  to  exceed ra ted  capac i ty  f o r  s h o r t  periods. The microprocessor c o n t r o l s  a r e  equipped with an RS-232 por t  f o r  telecolmaunica- t ions .  It i s  poas lb le  t o  remotely monitor the  c h i l l e r ,  run d iagnos t ics ,  and cor rec t  problems, g r e a t l y  reducing c o s t s  f o r  s e r v i c e  c a l l s .  The o r i g i n a l  design f o r  the  engine c h i l l e r  was experimental ly  i n s t a l l e d  a t  E l l i o t  Hospi tal  i n  Manchester, New Hampshire, t o  eva lua te  a c t u a l  system operat ions and i n s t a l l a t i o n  procedurer. The c h i l l e r  system, inc lud ing  t h e  absorp t ion  package, clthibited an average COP approaching 2.0. The engine c h i l l e r  supplements a  500-ton e l e c t r i c  c e n t r i f u g a l  c h i l l e r ,  which i s  g r e a t l y  oversized f o r  t h e  h o s p i t a l  cool ing requirements. The h o s p i t a l  i 3  p red ic t ing  a  30 percent  reduct ion i n  cooling cos t s .  Addit ional ly,  the engine c h i l l e r  is  much q u i e t e r  than the  e l e c t r i c  c e n t r i f u g a l .  The prel iminary r e s u l t s  of t h e  f i e l d  experi-  ment were in tegra ted  i n t o  a new design t h a t  r a d i c a l l y  s impl i f i ed  the  package and improved i ts performance. The new design i s  being t e s t e d  i n  a  seven u n i t  f i e l d  t e s t  dur ing  t h e  summer of 1987. Units  w i l l  be t e s t e d  i n  t h r e e  configurat ions:  simple mechanical c h i l l e r ,  engine c h i l l e r  with heat  recovery, and engine c h i l l e r  with absorp t ion  bottoming. The u n i t s  a r e  i n s t a l l e d  i n  severa l  comnercial applications, inc lud ing  h o t e l s ,  manufacturing f a c i l i t i e s ,  ahd o f f i c e  bu i ld ings .  Tecochi l l  CH-150 Fie?.-Test  S i t e  -Budget Inn, System Engine C h i l l e r  Cleveland Bleyle  of America, Engine C h i l l e r  Atlanta  Panhandle Eas te rn ,  EngineIAbsorption Kansas C i t y  B r i s t o l  Wyndham, Engine/Ht Recovery Washington Grossmont Center,  Engine C h i l l e r  San Diego NIGAS Division HQ, Engine C h i l l e r  Chicago Santa Monica Bay Engine Towers, Los Angeles Application Hotel Manuf ac t ur e  Off ice Hotel Off ice Off ice  Apartment The f i e l d  test should v e r i f y  t h e  performance of the engine c h i l l e r  i n  r e a l  world app l ica t ions .  The microproceesor con t ro l s  w i l l  monitor and record c r i t i c a l  opera t ing  d a t a  i n  15 minute i n t e r v a l s .  A c e n t r a l  d a t a  a c q u i s i t l o n  system w i l l  r e t r i e v e  t h e  da ta  d a i l y  and c o r r e l a t e  f l e e t  s t a t i s t i c s .  The f i e l d  t e s t  w i l l  a l s o  provide valuable information on i n s t a l l a t i o n  c o s t s  and procedures, and maintenance cos t s .  ECONOMICS OF ENCI NE-DRIVEN CHILLERS Market assessments and economic ana lyses  have demonstrated t h a t  a  huge p o t e n t i a l  f o r  gas-fueled engine-driven cool ing  s ystems e x i s t s ,  e ~ p z c i a l l y  i n  regions of t h e  United S t a t e s  t h a t  have high e l e c t r i c  demand charges.  The super io r  part-load performance of the  engine c h i l l e r ,  coupled with i t s  minimal e l e c t r i c  requirements ,  makes i t  an i d e a l  peaking u n i t .  Several  f a c t o r s  in f luence  t h e  u l t i m a t e  c o s t  of cool ing commercial bu i ld ings .  E l e c t r i c  c o s t s  must be d i f f e r e n t i a t e d  i n t o  demand charge, demand r a t c h e t ,  and energy cos t .  Hours of use a r e  typi-  c a l l y  determined by cool ing  degree days o r  equiva- l e n t  f u l l  load hours (EFLH) f o r  s p e c i f i c  regions.  Equipment performance must consider  c h i l l e r  COP and a u x i l i a r y  e l e c t r i c  l o a d s  requ i red  f o r  pumps, f a n s ,  and cont ro la .  Maintenance c o s t s  must be considered. Figure 1 comparQa t h e  c o s t  of e l e c t r i c  and gas cool ing i n  Chicago. Figures 2-7 i l l u s t r a t e  the  impact on a  n a t i o n a l  s c a l e  of varying these f a c t o r s .  The diagonal  l i n e  represen ts  a  three-year payback an the  c o s t  premium over  competi t ive elec- tr ic systems. C i t i e s  above t h e  diagonal  l i n e  have more a t t r a c t i v e ,  s h o r t e r  paybacks. Clear ly ,  the  f i r s t  c o s t ,  houra of  use,  and demand r a t c h e t  have s i g n i f i c a n t  impact of  the a t t r a c t i v e n e s s  of the  system FUTURE ENGINE-DRIVEN COOLING SYSTEMS The CRI development program has been expanded t o  a range of gas  e n g i n e d r i v e n  cool ing systems, from 15-ton DX packages t o  500-ton l i q u i d  c h i l l e r s .  Tecogen is  c u r r e n t l y  developing a  500-ton c h i l l e r  which u s e s  a  C a r r i e r  17DK twin open-drive c e n t r i -  fuga l  compreesor package. Each compressor w i l l  be d r iven  with a  tuned induc t ion  454-cubic-inch Chevrolet engine.  A COP of 1.9 is  ta rge ted .  A.G.A. Laboratories  is wor!cin~ wi th  Thermo King Corporation t o  develop a  15-ton roof top  package based on Thermo King's t r u c k - t r a i l e r  r e f r i g e r a t i o n  system. Thermo King has  manufactured engine- d r iven  t e f r i g e r a t i o n  systems f o r  48 years  and has a  nationwide s e r v i c e  network. Addi t iona l ly ,  GRI is e v a l u a t i n g  systems f o r  l o v t e m p e r a t u r e  r e f r i g e r a t i o n  and process appl ica-  t i o n s .  The incorpora t ion  of waste heat-driven absorp t ion  c h i l l e r s  t o  subcool l i q u i d  r e f r i g e r a n t  f u r t h e r  iaproves the cool ing performance of the  advanced system and reduces engine/comprrasor s i z e .  A mul t ip le  compressor engine-driven r e f r i g e r a t i o n  package f o r  supermarkets i a  undergoing f i e l d  t e s t s  i n  Los Angeles. The 150-ton engine-driven c h i l l e r  package should be commercially a v a i l a b l e  a s  e a r l y  a s  1988. The 500-ton package and e n g i n e d r i v e n  u n i t a r y  packages should be a v a i l a b l e  i n  1989. ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987ELECTRIC VS GAS CHILLER ANNUAL OPERATING COST COMPARISON $ - Dollars 20000 [ 18000 0 Maintenance 16000 I Aux. Energy GSl Aux. Demand 14000 lB3  Compressor Gas 12000 E Z I  Compressor Energy Compressor Demand 10000 8000 6000 4000 2000 0 Electric Engine sT3233.13 ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987SENSITIVITY TO FIRST COST Electric Energy Cost (*/kwh) 0 2 4 6 8 10 12 14 16 18 20 22 24 Demand Charge (S/kw) Summor, 1985 Rator, Largo Commorclal Bulldlngr. No Taxor or Surchargor Includod L-W3211.08 Ratchet Charger Applicable ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987SENSITIVITY TO GAS PRICE Electric Energy Cost (*/kwh) - - ~pp Sb Boas Cora Aaaumptlona: Fhrt Cort Premlum: S30/Ton Gar Englne: COP=1.5; AUX=O.19 KW/T; M8lnt=SO.O15 Elec Cantrf: COP=S.S; AUX=0.15 KW/T; MalnkS0.005 Houra: EFLH= 1200: Operatlng=2400 Gaa: S4/MIIBTU Damand Ralchat: 4 Month a NY' - - - i- - 0 2 4 6 8 10 12 14 16 18 20 22 24 Demand Charge (S/kw) Summar, 1985 Rstmr, Lsrga Commarclsl Bulldlngs. No Taxan or Surchergaa Inchdad L-W3211.03 Ratchet Charges Applicable ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987SENS ITIVITY TO EFLH Electric Energy Cost (*/kwh) Bare Caoo Aorumpllonr: Flral Coat Premium: S30/Ton Gar Englno: COPr1.5; AUXtO.19 KW/T; MalnlrSO.OlS Elec Centrf: COP=S.S; AUXt0.15 KW/T; Malnl=S0.005 Hourr: EFLH= 1200; Oporallngt2400 Gar: S4/MMETU Demand Ralchol: 4 Month 0 NV' - - - - - - 0 2 4 6 8 10 12 14 16 18 20 22 24 Demand Charge (S/kw) Summar, 1985 Ralam, Carga Commarclal Bulldlngm. No Taxam or Surchargam Includad ' Ralchet Chargeo Appllcabla L-W3277.00 ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987SENSITIVITY TO DEMAND RATCHET 0 2 4 6 8 10 12 14 16 18 20 22 24 Demand Charge (S/kw) Summmr, 1985 Ratmr, Largm Commmrcld Bulldlngr. No Taxer or Surchrrgmr Included ' Ratchet Charger Appllcrbk L-W3277.04 ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987SENSITIVITY TO MAINTENANCE Electric Energy Cost (*/kwh) 0 2 4 6 8 10 12 14 16 18 20 22 24 Demand Charge (S/kw) Summor, 1985 Rator, Largo Commorclrl Bulldlngr. No Traor or Surchrrgor lncludod Ratchet Charges Appllcablo L-WJ277.07 ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987SENSITIVITY TO AUXILIARY POWER REQUIREMENTS Electric Energy Cost (@/kwh) Bara Cara Assurnpllanr: Flrrt Coat Prernlurn~ S30/Ton Gar Engine: COP=1.5; AUXr0.19 KW/T; Malnt=S0.015 Elac Cantrl: C0P15.5; AUXrO.15 K W / T  Malnt=S0.005 Hourr: EFLH=: 1200; Oparatlng=2400 l 6 - 3 - 2 - 1 - 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Demand Charge ($/kw) Summor, 1985 Ratmm, Largo Commmrclal Bulldlngm. No Taxme or Surcharges Includod Ratchel Chargem Appllcsble L-WS277.05 ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987ESL-HH-87-09-16Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987

Gas -Fueled Engine-Driven Air Conditioning Systems for Commercial Buildings

Texas A&M University

GAS-FUELED ENGINE-DRIVEN AIR CONDITIONING SYSTEMS FOR COMMERCIAL BUILDINGS 
BRUCE B. LINDSAY 
Pro jec t  Manager, Space Conditioning 
Gas Research I n s t i t u t e  
INTRODUCTION 
-- - 
In 1985, the Gas Research I n s t i t u t e  (GRI) 
i n i t i a t e d  a  program with Tecogen, Inc.. t o  develop 
a  nominal 150-ton gas-f ueled engine-driven water 
c h l l l e r  f o r  commercial bui ldings.  The packaged 
system has been designed,  f a b r i c a t e d ,  and operated 
s a t i s f a c t o r i l y  i n  the l abora tory  and i n  a  450-bed 
h o s p i t a l .  The engine c h i l l e r  has been redesigned 
t o  improve performance, increase  capac i ty ,  and 
reducc the f o o t p r i n t ,  and is undergoing f i e l d  
t e s t s  a t  seven s i t e s  to  v e r i f y  perfonnance a?d 
r e l i a b i l i t y .  
COMMERCIAL COOLING MARKET 
In 1967, t h e  commercial market  purchased 
approximately 83,600 u n i t s  with coo l ing  c a p a c i t i e s  
g rea te r  than 5  tons. Of t h a t ,  1 ,601 absorpt ion 
cool ing systems were s o l d  with a  t o t a l  capac i ty  of  
528,000 tons,  represen t ing  27.6 percent of t h e  
t o t a l  market. In 1984, near ly  134,000 u n i t s  were 
purchased, but only 82 absorpt ion machines, 27,100 
tons,  were so ld .  Gas cool ing represented only 0.8 
percant of the  market. 
Several  f a c t o r s  can be c r e d i t e d  f o r  t h i s  
s i g n i f i c a n t  l o s s  t o  the n a t u r a l  gas  indus t ry :  
E l e c t r i c  p r ices  decl ined i n  r e a l  d o l l a r s .  The 
performance of  electr ic-motor  d r iven  vapor compres- 
s ion cooling systems improved and the  equipment 
p r ices  decreased. Gas c o s t s  esca la ted  rap id ly  and 
suppl ies  were assumed t o  be inadequate.  Mainte- 
nance c o s t s  f o r  e l e c t r i c  systems were low and 
r e l i a b i l i t y  good. 
In recent  years ,  these  t rends  have begun t o  
reverse.  E l e c t r i c  p r i c e s  have esca la ted  r a p i d l y  
a s  cap i ta l - in tens ive  nuclear  power p l a n t s  have 
been added t o  t h e  u t i l i t y  r a t e  bas?. These 
increases  have been shouldered primari ly  by the  
commercial bu i ld ing  segment, which has l i t t l e  
p o l i t i c a l  o r  economic recourse. The u t i l i t i e s ,  
faced with h o s t i l e  regu la tory  review and permit- 
t ing  procedures, a r e  unwil l ing t o  i n v e s t  i n  new 
p lan t  cons t ruc t ion .  Demand may exceed genera t ing  
capaci ty i n  many a reas  of the country and necessi-  
t a t e  brow-outs  o r  cur ta i lment .  Gas c o s t s ,  on the  
o ther  hand, have s t a b i l i z e d  and even decreased f o r  
c e r t a i n  regions.  Gas supply i s  now s u f f i c i e n t  
i n t o  the next century a t  reasonable costs .  The 
commercial market is  c l e a r l y  posi t ioned t o  
consider gas cool ing a s  a  v i a b l e  a l t e r n a t i v e .  
Direct-f i red absorp t ion  c h i l l e r / h e a t e r  
s y s t m s  have made s i g n i f i c a n t  in-roads i n t o  t h e  
commercial market. These Japanese systems a r e  
near ly  40 percent  more e f f i c i e n t  than t h e i r  
s ingle-eff  e c t  predecessors. Unf o re  unately , t h e  
tumultuous fore ign  exchange m a r k  t has placed 
these  u n i t s  a t  a  severe  disadvantage. The high 
f i r s t  c o s t  of absorp t ion  systems can only be 
j u s t i f i e d  i n  those regions of t h e  United S t a t e s  
with extremely high e l e c t r i c  r a t e s .  
ENGINE-DRIVEN COOLING SYSTEMS 
Absorption i s  not the only gas-f i red a i r  
condit ioning op t ion .  A gas-fueled engine can 
d r i v e  a  r e f r i g e r a t i o n  compressor, rep lac ing  an 
e l e c t r i c  motor, and achieve t h e  same performance 
per s h a f t  horsepower. The gas engine has an 
e f f i c i e n c y  of 30 percent  (HHV), which is  cotnpar- 
a b l e  t o  the e f f i c i e n c y  of an e l e c t r i c  generat ion 
p l a n t .  The engine c h i l l e r  should achieve a 
c o e f f i c i e n t  of performance (COP) of 1.7, a  70 
percent  improvement over d i r e c t - f i r e d  absorpt ion 
c h i l l e r s .  Addi t iona l ly ,  t h e  engine c h i l l e r  can 
leverage the  advances i n  e l e c t r i c  c h i l l e r  technol- 
ogy t o  ob ta in  a  vs ry  c m p e t l t i v e  f i r s t  c o s t .  
Gas engine-driven cool ing  systems were very 
popular i n  t h e  e a r l y  S i x t i e s .  Major engine manu- 
f a c t u r e r s ,  such a s  C a t e r p i l l a r ,  Waukesha, and 
Continental  , marketed t h e i r  products t o  numerous 
packagers, such a s  Ready Power, Gascool, and 
Comf ortTemp. Approximately 2,000 engine-driven 
sys  tems were sold t o  c o m e r c i a l  and i n d u s t r i a l  
f i rms.  Nearly 25 y e a r s  l a t e r ,  many of those 
systems a r e  s t i l l  opera t ing .  These systems demon- 
s t r a t e d  high r e l i a b i l i t y  when properly maintained. 
However, poor maintenance o f t e n  r e s u l t e d  i n  eatas-  
t r o p h i c  f a i l u r e  and system removal. 
I n  1985, t h e  Gas Research I n s t i t u t e  (GII) 
i n i t i a t e d  a  program with Tecogen, Inc.  , t o  develop 
a  nominal 150-ton gas-fueled engine-driven water 
c h i l l e r  f o r  commercial bu i ld ings .  The engine 
c h i l l e r  would c a p i t a l i z e  on Tecogen's experience 
i n  packaged cogenerat ion systems and u t i l i z e  t h e  
454-cubic-inch Chevrolet engine used i n  t h e i r  
bes t - s e l l i n g  60-kW package. Tine mass-produced 
automotive engine has v e r y  low c o s t  and e x c e l l e n t  
d u r a b i l i t y .  Severa l  engines have exceeded 20,000 
hours  of opera t ion .  Waste hea t  from t h e  zngine 
jacke t  and exhaust can be recovered a s  hot  water 
f o r  pool h e a t i n g ,  domestic water h e a t i n g ,  and 
space heat ing.  The hot  water can a l s o  d r i v e  an 
op t iona l  absorp t ion  c h i l l e r  t o  produce a  
supplemental 30-35 tons of cool ing.  
The engine c h i l l e r  has  been designed and 
t e s t e d  with s e v e r a l  d i f f e r e n t  components. The 
c u r r e n t  system i s  comprised of the  Chevrolet 
engine,  a  Howden screw compressor, advanced 
microprocessor c o n t r o l s ,  an o i l  s e p a r a t o r ,  an 
economizer, and condenser and evaporator  bundles. 
The engine c h i l l e r  h a s  produced 142 tons  of 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
cooling a t  a  c o e f f i c i e n t  of performance (COP) of 
1.4 a t  ARI f u l l  load condit ions.  The c h i l l e r  i s  
r a t e 3  a t  an engine speed of 2920 r p  and output  of 
147 horsepower. The engine can vary i t s  s p e d  
from 1000 rpm t o  3300 rpm t o  meet varying load 
condit ions.  The var iab le  speed operat ion g r e a t l y  
improves t h e  part-load performance of the c h i l l e r  
and permits the  c h i l l e r  to  exceed ra ted  capac i ty  
f o r  s h o r t  periods. The microprocessor c o n t r o l s  
a r e  equipped with an RS-232 por t  f o r  telecolmaunica- 
t ions .  It i s  poas lb le  t o  remotely monitor the  
c h i l l e r ,  run d iagnos t ics ,  and cor rec t  problems, 
g r e a t l y  reducing c o s t s  f o r  s e r v i c e  c a l l s .  
The o r i g i n a l  design f o r  the  engine c h i l l e r  
was experimental ly  i n s t a l l e d  a t  E l l i o t  Hospi tal  i n  
Manchester, New Hampshire, t o  eva lua te  a c t u a l  
system operat ions and i n s t a l l a t i o n  procedurer. The 
c h i l l e r  system, inc lud ing  t h e  absorp t ion  package, 
clthibited an average COP approaching 2.0. The 
engine c h i l l e r  supplements a  500-ton e l e c t r i c  
c e n t r i f u g a l  c h i l l e r ,  which i s  g r e a t l y  oversized 
f o r  t h e  h o s p i t a l  cool ing requirements. The 
h o s p i t a l  i 3  p red ic t ing  a  30 percent  reduct ion i n  
cooling cos t s .  Addit ional ly,  the engine c h i l l e r  
is  much q u i e t e r  than the  e l e c t r i c  c e n t r i f u g a l .  
The prel iminary r e s u l t s  of t h e  f i e l d  experi-  
ment were in tegra ted  i n t o  a new design t h a t  
r a d i c a l l y  s impl i f i ed  the  package and improved i ts 
performance. The new design i s  being t e s t e d  i n  a  
seven u n i t  f i e l d  t e s t  dur ing  t h e  summer of 1987. 
Units  w i l l  be t e s t e d  i n  t h r e e  configurat ions:  
simple mechanical c h i l l e r ,  engine c h i l l e r  with 
heat  recovery, and engine c h i l l e r  with absorp t ion  
bottoming. The u n i t s  a r e  i n s t a l l e d  i n  severa l  
comnercial applications, inc lud ing  h o t e l s ,  
manufacturing f a c i l i t i e s ,  ahd o f f i c e  bu i ld ings .  
Tecochi l l  CH-150 Fie?.-Test  
S i t e  
-
Budget Inn, 
System 
Engine C h i l l e r  
Cleveland 
Bleyle  of America, Engine C h i l l e r  
Atlanta  
Panhandle Eas te rn ,  EngineIAbsorption 
Kansas C i t y  
B r i s t o l  Wyndham, Engine/Ht Recovery 
Washington 
Grossmont Center,  Engine C h i l l e r  
San Diego 
NIGAS Division HQ, Engine C h i l l e r  
Chicago 
Santa Monica Bay Engine 
Towers, Los Angeles 
Application 
Hotel 
Manuf ac t ur e  
Off ice 
Hotel 
Off ice 
Off ice  
Apartment 
The f i e l d  test should v e r i f y  t h e  performance 
of the engine c h i l l e r  i n  r e a l  world app l ica t ions .  
The microproceesor con t ro l s  w i l l  monitor and record 
c r i t i c a l  opera t ing  d a t a  i n  15 minute i n t e r v a l s .  A 
c e n t r a l  d a t a  a c q u i s i t l o n  system w i l l  r e t r i e v e  t h e  
da ta  d a i l y  and c o r r e l a t e  f l e e t  s t a t i s t i c s .  The 
f i e l d  t e s t  w i l l  a l s o  provide valuable information 
on i n s t a l l a t i o n  c o s t s  and procedures, and 
maintenance cos t s .  
ECONOMICS OF ENCI NE-DRIVEN CHILLERS 
Market assessments and economic ana lyses  have 
demonstrated t h a t  a  huge p o t e n t i a l  f o r  gas-fueled 
engine-driven cool ing  s ystems e x i s t s ,  e ~ p z c i a l l y  
i n  regions of t h e  United S t a t e s  t h a t  have high 
e l e c t r i c  demand charges.  The super io r  part-load 
performance of the  engine c h i l l e r ,  coupled with 
i t s  minimal e l e c t r i c  requirements ,  makes i t  an 
i d e a l  peaking u n i t .  
Several  f a c t o r s  in f luence  t h e  u l t i m a t e  c o s t  
of cool ing commercial bu i ld ings .  E l e c t r i c  c o s t s  
must be d i f f e r e n t i a t e d  i n t o  demand charge, demand 
r a t c h e t ,  and energy cos t .  Hours of use a r e  typi-  
c a l l y  determined by cool ing  degree days o r  equiva- 
l e n t  f u l l  load hours (EFLH) f o r  s p e c i f i c  regions.  
Equipment performance must consider  c h i l l e r  COP 
and a u x i l i a r y  e l e c t r i c  l o a d s  requ i red  f o r  pumps, 
f a n s ,  and cont ro la .  Maintenance c o s t s  must be 
considered. Figure 1 comparQa t h e  c o s t  of e l e c t r i c  
and gas cool ing i n  Chicago. Figures 2-7 i l l u s t r a t e  
the  impact on a  n a t i o n a l  s c a l e  of varying these 
f a c t o r s .  The diagonal  l i n e  represen ts  a  three-year 
payback an the  c o s t  premium over  competi t ive elec- 
tr ic systems. C i t i e s  above t h e  diagonal  l i n e  have 
more a t t r a c t i v e ,  s h o r t e r  paybacks. Clear ly ,  the  
f i r s t  c o s t ,  houra of  use,  and demand r a t c h e t  have 
s i g n i f i c a n t  impact of  the a t t r a c t i v e n e s s  of the  
system 
FUTURE ENGINE-DRIVEN COOLING SYSTEMS 
The CRI development program has been expanded 
t o  a range of gas  e n g i n e d r i v e n  cool ing systems, 
from 15-ton DX packages t o  500-ton l i q u i d  c h i l l e r s .  
Tecogen is  c u r r e n t l y  developing a  500-ton c h i l l e r  
which u s e s  a  C a r r i e r  17DK twin open-drive c e n t r i -  
fuga l  compreesor package. Each compressor w i l l  be 
d r iven  with a  tuned induc t ion  454-cubic-inch 
Chevrolet engine.  A COP of 1.9 is  ta rge ted .  
A.G.A. Laboratories  is wor!cin~ wi th  Thermo King 
Corporation t o  develop a  15-ton roof top  package 
based on Thermo King's t r u c k - t r a i l e r  r e f r i g e r a t i o n  
system. Thermo King has  manufactured engine- 
d r iven  t e f r i g e r a t i o n  systems f o r  48 years  and has 
a  nationwide s e r v i c e  network. 
Addi t iona l ly ,  GRI is e v a l u a t i n g  systems f o r  
l o v t e m p e r a t u r e  r e f r i g e r a t i o n  and process appl ica-  
t i o n s .  The incorpora t ion  of waste heat-driven 
absorp t ion  c h i l l e r s  t o  subcool l i q u i d  r e f r i g e r a n t  
f u r t h e r  iaproves the cool ing performance of the  
advanced system and reduces engine/comprrasor s i z e .  
A mul t ip le  compressor engine-driven r e f r i g e r a t i o n  
package f o r  supermarkets i a  undergoing f i e l d  t e s t s  
i n  Los Angeles. 
The 150-ton engine-driven c h i l l e r  package 
should be commercially a v a i l a b l e  a s  e a r l y  a s  
1988. The 500-ton package and e n g i n e d r i v e n  
u n i t a r y  packages should be a v a i l a b l e  i n  1989. 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
ELECTRIC VS GAS CHILLER 
ANNUAL OPERATING COST COMPARISON 
$ - Dollars 
20000 [ 
18000 0 Maintenance 
16000 
I Aux. Energy 
GSl Aux. Demand 
14000 lB3  Compressor Gas 
12000 E Z I  Compressor Energy 
Compressor Demand 
10000 
8000 
6000 
4000 
2000 
0 
Electric Engine 
sT3233.13 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
SENSITIVITY TO FIRST COST 
Electric Energy Cost (*/kwh) 
0 2 4 6 8 10 12 14 16 18 20 22 24 
Demand Charge (S/kw) 
Summor, 1985 Rator, Largo Commorclal Bulldlngr. No Taxor or Surchargor Includod 
L-W3211.08 Ratchet Charger Applicable 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
SENSITIVITY TO GAS PRICE 
Electric Energy Cost (*/kwh) 
- - ~pp 
Sb Boas Cora Aaaumptlona: 
Fhrt Cort Premlum: S30/Ton 
Gar Englne: COP=1.5; AUX=O.19 KW/T; M8lnt=SO.O15 
Elec Cantrf: COP=S.S; AUX=0.15 KW/T; MalnkS0.005 
Houra: EFLH= 1200: Operatlng=2400 
Gaa: S4/MIIBTU 
Damand Ralchat: 4 Month 
a 
NY' 
- 
- 
- 
i- 
- 
0 2 4 6 8 10 12 14 16 18 20 22 24 
Demand Charge (S/kw) 
Summar, 1985 Rstmr, Lsrga Commarclsl Bulldlngs. No Taxan or Surchergaa Inchdad 
L-W3211.03 Ratchet Charges Applicable 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
SENS ITIVITY TO EFLH 
Electric Energy Cost (*/kwh) 
Bare Caoo Aorumpllonr: 
Flral Coat Premium: S30/Ton 
Gar Englno: COPr1.5; AUXtO.19 KW/T; MalnlrSO.OlS 
Elec Centrf: COP=S.S; AUXt0.15 KW/T; Malnl=S0.005 
Hourr: EFLH= 1200; Oporallngt2400 
Gar: S4/MMETU 
Demand Ralchol: 4 Month 
0 
NV' 
- 
- 
- 
- 
- 
- 
0 2 4 6 8 10 12 14 16 18 20 22 24 
Demand Charge (S/kw) 
Summar, 1985 Ralam, Carga Commarclal Bulldlngm. No Taxam or Surchargam Includad 
' Ralchet Chargeo Appllcabla L-W3277.00 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
SENSITIVITY TO DEMAND RATCHET 
0 2 4 6 8 10 12 14 16 18 20 22 24 
Demand Charge (S/kw) 
Summmr, 1985 Ratmr, Largm Commmrcld Bulldlngr. No Taxer or Surchrrgmr Included 
' Ratchet Charger Appllcrbk L-W3277.04 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
SENSITIVITY TO MAINTENANCE 
Electric Energy Cost (*/kwh) 
0 2 4 6 8 10 12 14 16 18 20 22 24 
Demand Charge (S/kw) 
Summor, 1985 Rator, Largo Commorclrl Bulldlngr. No Traor or Surchrrgor lncludod 
Ratchet Charges Appllcablo L-WJ277.07 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
SENSITIVITY TO AUXILIARY POWER REQUIREMENTS 
Electric Energy Cost (@/kwh) 
Bara Cara Assurnpllanr: 
Flrrt Coat Prernlurn~ S30/Ton 
Gar Engine: COP=1.5; AUXr0.19 KW/T; Malnt=S0.015 
Elac Cantrl: C0P15.5; AUXrO.15 K W / T  Malnt=S0.005 
Hourr: EFLH=: 1200; Oparatlng=2400 
l 
6 - 
3 - 
2 - 
1 - 
0 
0 2 4 6 8 10 12 14 16 18 20 22 24 
Demand Charge ($/kw) 
Summor, 1985 Ratmm, Largo Commmrclal Bulldlngm. No Taxme or Surcharges Includod 
Ratchel Chargem Appllcsble 
L-WS277.05 
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987
ESL-HH-87-09-16
Proceedings of the Fourth Symposium on Improving Building Systems in Hot and Humid Climates, Houston, TX, September 15-16, 1987


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Gas -Fueled Engine-Driven Air Conditioning Systems for Commercial Buildings

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Texas A&M Repository

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Gas -Fueled Engine-Driven Air Conditioning Systems for Commercial Buildings

Abstract

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Full text

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Texas A&amp;M Repository

Texas A&M University

Texas A&M Repository