Vapour Compression-Absorption Hybrid Refrigeration Systems

Transcription

1 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems CHAPER 4 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems 4.1 Intrductin e tw majr prblems are swing teir dminance in te refrigeratin and aircnditining sectr, te first ne is pasing ut f algenated flurcarbn as prpsed by Mntreal Prtcl and te secnd ne is t minimize te use f cnventinal energy wic in turn leads t envirnmental degradatin as well as glbal warming. e refrigeratin and air cnditining systems cnsume a majr prtin f energy and demand as increased substantially many flds in te recent years due t an increased level f termal cmfrt as well as variety f applicatins in te dmestic as well as industrial sectrs. e absrptin refrigeratin system represents a unique tecnlgy fr cling and eating applicatin using nn-cnventinal energy r lw grade energy surces like slar, getermal, bimass, waste eat frm te industries etc. Mrever, suc systems cause zer r minimum zne depletin because tey dn t use any CFC r HFCs refrigerant as wrking fluid (Abdulla and Hien, 2011; Anand et al., 2014). e review studies f different refrigeratin systems revealed tat termal srptin systems are cmparatively cst effective tan slar electric and termmecanical systems (Kim and Ferreira, 2008; Anand et al., 2014). In extensin t te previus mentined wrks, many autrs ave carried ut analysis f different types f slar energy pwered absrptin refrigeratin systems fr cling and eating applicatins and utcmes straigtway revealed tat perfrmance f te system depends n perating parameters and capacity f te system (Mazlumi et al., 2008; El Fadar et al., 2009; Vargas et al., 2009; Ozgren et al., 2012). 85

2 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems e teretical analysis f vapur cmpressin absrptin systems using different wrking fluids cncluded tat R502A is a better wrking fluid because f iger COP and exergy efficiency in cmparisn t R507 and R404A wen perated under same cndenser and evapratr temperature wereas cndenser is fund t be te wrst cmpnent in terms f irreversibility and needs mdificatins in rder t imprve te perfrmance f te system (Arra & Kausik, 2008). e perfrmance study f cmpressin-absrptin cascaded refrigeratin systems using getermal energy cncluded tat perfrmance f suc systems is better tan single stage refrigeratin systems wic can furter be imprved (Kairuani and Nedi, 2006). Again, utcmes btained frm cgeneratin pwered cmpressin-absrptin cascade refrigeratin systems t generate cling at lw temperature were fund t be appreciable frm te view pint f system design (Fernandez-Seara et al., 2006). A cmparative analysis f different wrking fluid pairs fr cmpressin-absrptin refrigeratin system fr simultaneus cling and eating applicatins swed tat system capacity influences perfrmance f te wrking fluid (Satapaty et al., 2007). A detailed analysis f a 400 kw ammnia-water cmpressinabsrptin refrigeratin system (fr air-cnditining applicatin) t study effect f slutin eat excanger area, mass flw rate f weak slutin, cling capacity and eat lad f absrber n te cling capacity revealed tat COP f te system is influenced by mass flw rate f weak slutin (Pratiar et al., 2010). A cascaded cmpressin-absrptin refrigeratin cycle using litium-brmide fr absrptin system and subcritical CO 2 fr vapur cmpressin cycle capable t prvide lw temperature refrigerant, medium temperature refrigerant and medium temperature rejected eat ave been analysed wic can furter be used fr different applicatins (Garimella et al., 2011) and results btained sw iger COP and energy saving wen cmpared t a cnventinal vapur cmpressin system. 86

3 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Waste eat driven cmpressin absrptin eat pump using ammnia-water as wrking fluid ave been analyzed and findings revealed tat suc systems can prvide larger temperature glide and flexible perating range wen cmpared t a cnventinal vapur cmpressin eat pump (Kim et al., 2013). e applicatin f bigas in absrptin refrigeratin system revealed tat bigas prvides a gd energy ptential fr te peratin f refrigeratin systems (Anand et al., 2014). Hwever, results btained frm study indicate tat te igest exergy lss is fund in generatr wile te lwest is fund in cndenser and exergy lsses in absrber are mre in cmparisn t cndenser wic is te actual case. e results btained frm experimental as well as teretical investigatins f a ybrid refrigeratin system cnsisting f vapur cmpressin system and crygenic refrigeratin system revealed abut te primary and final energy cnsumptin in te ybrid system (Gazda and Kził, 2013). Hwever, cmparisn f COP and primary energy cnsumptin fr vapur cmpressin system and crygenic refrigeratin system was als presented. An exergy based substantial review n te applicatins (direct r indirect) f different renewable energy surces wic includes slar energy, ptvltaic termal cllectrs, wind energy, getermal energy, bimass etc. fr sustainable future cncluded tat study will be quite beneficial fr te individuals interested in te design, simulatin and perfrmance assessment (Hepbasli, 2008). e utcmes f experimental study f slar bimass ybrid air cnditining system at quasi steady state cncluded tat verall btained COP lies in te range f 0.11 wic is superir wen cmpared t ter similar studies (Prasartkaew and Kumar, 2013). e perfrmance f individual cmpnents as als been evaluated. Based n literature review, present capter deals wit te analysis f waste eat and bigas perated vapur cmpressin-absrptin ybrid systems. e analysis f waste eat 87

4 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems driven ybrid system sws te cmparative termdynamic analysis based n numerical metds suitable t be perated in tree different mdes. Hwever, energy and exergy analysis f a bigas perated ybrid system fr nsite dairy applicatins as als been carried ut. e special empasis in bt analyzed systems lies n te effects f varius perating parameters n te perfrmance f systems. e pwer cnsumptin f cmpressr is als calculated fr te analyzed systems. e main aim f study is t ptimize te peratin f suc systems witut cmprmising te perfrmance. 4.2 System Descriptin and Wrking Principle f Waste Ht Water Operated Vapur Cmpressin-Absrptin Hybrid System e prpsed ybrid system as swn in Figure 4.1 is capable t be perated in different mdes and can be utilized rund te clck depending upn te availability f specific energy surces i.e. waste t water r cnventinal energy. e different mdes f peratin are: i. Vapur Absrptin System (VA system) - wen valve V 1 is pen and ter valves V 2, V 3 & V 4 are clsed. ii. Vapur Cmpressin-Absrptin System (VCA system) - wen valves V 1, V 2 & V 3 are pen and valve V 4 is clsed. iii. Vapur Cmpressin System (VC system) - wen valves V 3 & V 4 are pen and valves V 1 & V 2 are clsed. e first tw mdes described abve i.e. VA mde and VCA mde can be perated wit waste t water, but te tird system described abve requires te applicatin f cnventinal energy fr its peratin. e VA and VCA mdes f peratin use ammniawater as refrigerant-absrbent pair wile VC mde f system uses nly ammnia as wrking fluid. e prpsed system cnsists f a generatr, cndenser, absrber, evapratr, slutin 88

5 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems eat excanger, trttling device, pressure reducing valve, pump, cndenser, valves and cmpressr. Q G 12 COMPRESSOR Q C GENERAOR V 2 V 3 CONDENSER HEA EXCHANGER rttling valve Pump PR-VALVE 11 V 4 6 ABSORBER V 1 7 EVAPORAOR 7 Q A Q E Figure 4.1: A scematic line diagram f a waste eat perated vapur cmpressin- absrptin ybrid system In VA mde, slutin ric in refrigerant exits te absrber (8) wic is pumped trug slutin pump (9) t te slutin eat excanger and is eated by weak slutin tat cmes frm generatr. e strng slutin enters generatr (1) were ammnia is raised int vapurs by external eat supply frm waste t water and separates frm te slutin. e ammnia vapur exits generatr (12) because valves V 2 and V 3 are kept clsed wile te weak slutin returns t absrber trug slutin eat excanger (3-10) and lwers its 89

6 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems pressure by pressure reducing valve (10-11). e ammnia vapurs are cndensed in cndenser and latent eat f cndensatin is released int cling water flwing trug cndenser. e ammnia liquid wic is prduced in cndenser (5) is at iger pressure and is passed trug te trttling device (5-6) t reduce its pressure. At tis lw pressure saturated liquid ammnia enters evapratr were it is again cnverted int vapurs by absrbing te latent eat frm cilled water circulated between evapratr and cling space. e refrigerant vapurs prduced enter absrber (7) via valve V 1 were tey are absrbed by strng slutin and eat f absrptin is released int te circulating fluid flwing trug absrber. e strng slutin is ten released trug absrber eiter in saturated r in a sligtly sub-cled state. is prcess is cntinued and refrigerating effect/cling is prduced. e VCA system perates in te same way as discussed abve, but tere is a difference tat refrigerant vapurs s generated in generatr are allwed t pass in t te cmpressr (2-4) trug valves V 1 and V 2 t raise temperature and pressure f te wrking fluid. e VC system uses circulating ammnia as te wrking medium wic remves eat frm te space t be cled. Circulating refrigerant enters cmpressr in a termdynamic state knwn as a saturated vapur (7) trug valve V 4 and is cmpressed t a iger pressure, resulting in a iger temperature as well. e t, cmpressed vapur is ten in te termdynamic state knwn as a supereated vapur and it is at a temperature and pressure at wic it can be cndensed in a cndenser. is is were circulating refrigerant rejects eat frm system and rejected eat is carried away by eiter water r air. e cndensed liquid refrigerant, in te termdynamic state knwn as a saturated liquid, is expanded in an expansin valve (5) were it underges a reductin in pressure (6). At tis lw pressure, saturated liquid ammnia enters evapratr were it is again cnverted int vapurs by absrbing eat frm space t be cled tereby prducing te cling effect. 90

7 4.3 ermdynamic Analysis Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems e termdynamic analysis invlves analysis f te system in all tree mdes f peratin as described in previus sectin and is based n te applicatin f principles f mass cnservatin, species cnservatin, first law f termdynamics and secnd law f termdynamics. e analysis is carried ut fr 1 R cling capacity ybrid refrigeratin systems and is based n te assumptins given belw: (a). System perates at steady state cnditins and eat lss trug cnducting pipes is negligible. (b). Slutin leaving absrber and generatr is assumed t be saturated at teir respective temperatures and cncentratins. (c). (d). (e). e refrigerant leaving cndenser and evapratr is assumed t be saturated. e pressure drp in valves is cnsidered t be negligible. e pump wrk is neglected in te analysis as it cnsidered t be wrking at isentalpic cnditins. Als, expansin valves and flw valves were cnsidered t be isentalpic. (f). e mass flw rate f refrigerant at state pints 2, 4, 5, 6, 7 & 12 is assumed t be same. (g). (). (i). e mass flw rate f weak slutin at state pints 3, 10 &11 is assumed t be same. e mass flw rate f strng slutin at state pints 1, 8 & 9 is assumed t be same. e reference entalpy ( ) and te entrpy (s ) is taken at temperature and pressure f 25 C and 1 bar respectively. (j). e efficiency f cmpressr is assumed t be 0.7 and te effectiveness f slutin eat excange is taken as

8 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems (k). e evapratr temperature (5 C) and cndenser temperature (40 C) is assumed t be same fr all te tree mdes f system peratin in case f waste eat perated ybrid refrigeratin system. (l). e temperature f water feed in te bigas biler is cnsidered cnstant at 30 C wic gets eated wit bigas and tis eated fluid furter can be used fr te wrking f ybrid cmpressin-absrptin refrigeratin system witut any temperature drp. (m). e temperature f water at te exit f generatr is als cnsidered t be at 30 C wic again can be fed in t te bigas biler fr clsed cycle peratin. 4.4 Energy Analysis e generalized gverning equatins f mass cnservatin, species cnservatin and energy cnservatin used in te analysis are same as detailed in equatins 3.11, 3.12 and 3.13 respectively. e energy balance equatins f different mdes f peratin f ybrid refrigeratin system are given belw as: Energy Analysis in Vapur Absrptin Mde Fr te termdynamic analysis f vapur absrptin mde, energy balance f varius cmpnents is calculated based n varius assumptins as listed abve and te parameters given in able 4.1. e respective eat lads and energy balance f different cmpnents are given as belw: Energy balance at generatr Q G m 12 m m1 1 (4. 1) Energy balance at absrber Q A m127 m311 m1 8 (4. 2) 92

9 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Energy balance at evapratr Q E m (4. 3) Energy balance at cndenser Q C m Energy balance at eat excanger Q SHE m m (4. 4) (4. 5) e perfrmance f vapur absrptin mde can be calculated in terms f COP and different equatins wic are used in te analysis f COP fr cling and eating applicatins are same as in te equatins 3.22, 3.23 and 3.24 respectively in capter Energy Analysis in Vapur Cmpressin Mde Fr termdynamic analysis f vapur cmpressin mde f system, energy balance f varius cmpnents is calculated based n varius assumptins as mentined abve and parameters given in able 4.1. e respective energy balance equatins f different cmpnents are given as belw: Energy balance at evapratr Q E m (4. 6) Energy balance at cndenser Q C m (4. 7) Wrk dne by cmpressr W C, VC m 2 4 C 7 (4. 8) 93

10 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems able 4.1: Operating cnditins and fixed parameters adpted fr numerical simulatin f waste t water perated ybrid system Operating parameters Generatr pressure Evapratr pressure Generatr temperature (VA & VCA system) Evapratr temperature (VA,VC & VCA system) Absrber temperature (VA & VCA system) Cndenser temperature (VA,VC & VCA system) Ambient pressure Ambient temperature Fixed values 12 bar 2 bar K K K K 1 bar K Cmpressr efficiency 0.7 Effectiveness f slutin eat excanger 0.83 e refrigeratin system can be cnsidered as a perfectly reversible system and cling COP f VCR system is defined as eat lad in evapratr per unit f pwer cnsumptin in te cmpressr and is expressed as: COP cling Q W C, VC E (4. 9) e eat rejected frm te cndenser can als be used fr eating applicatins by allwing water r air t flw trug cndenser and COP f te system fr eating applicatins is given as: COP Q W C, VC C eating (4. 10) 94

11 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Energy Analysis in a Vapur Cmpressin-Absrptin mde Fr termdynamic analysis f vapur cmpressin-absrptin mde, energy balance f varius cmpnents is calculated based n varius assumptins as listed abve and parameters given in able 4.1. e respective eat lads and energy balance f cmpnents are given as belw: Energy balance at generatr Q G m 2 2 m 3 3 m 11 (4. 11) Energy balance at absrber Q A m 2 7 m 311 m 18 (4. 12) Energy balance at evapratr Q E m (4. 13) Energy balance at cndenser Q C m (4. 14) Energy balance at eat excanger m m (4. 15) Q SHE Wrk dne by cmpressr W C, VCA m 2 2 C 4 (4. 16) e COP f te prpsed mde f peratin is given belw: COP cling G Q W C, VCA E (4. 17) Q In case f suc refrigeratin systems eat rejected frm cndenser as well as absrber can als be utilized fr eating purpses eiter by allwing water r air t flw trug 95

12 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems cndenser. e system can be used fr eating purpses als and COP f te system is given as belw: COP eating Q Q Q W C A (4. 18) G C, VCA Were, Q C and Q A are rejected eat rates frm cndenser and absrber respectively t water r air and Q G is energy supplied t te generatr/ eat surce. 4.5 Exergy Analysis In rder t ptimize te system termdynamically, exergy analysis as been carried ut. e use f irreversibility, wic is a measure f prcess imperfectin, leads t lcate cause f irreversibility as well as elp t determine te ptimum perating cnditins. e generalized exergy balance equatin used in te analysis is similar t equatin e exergy balance equatins f different mdes f peratin f ybrid system are given belw as: Exergy Balance in Vapur Absrptin Mde Exergy balance at generatr G m s1 s m s12 s m s s Q G G (4.19) Exergy balance at absrber A m s s m s s m s s Exergy balance at cndenser Q A 1 A (4.20) C s m s 5 QC 1 A (4. 21) 96

13 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Exergy balance at evapratr s E m s 7 + Q E 1 (4. 22) E Exergy balance at slutin eat excanger s m s10 (4. 23) SHE Exergy efficiency e secnd law perfrmance f te system can be measured in terms f exergy efficiency wic is same as expressed in equatin 3.31 in capter Exergy Balance in Vapur Cmpressin mde Exergy balance at cndenser s C m s 5 - QC 1 A Exergy balance at evapratr s E m s 7 + Q E 1 E Exergy balance at cmpressr s s C (4. 24) (4. 25) m C VC, (4. 26) Exergy Efficiency e secnd law perfrmance f te system can be measured in terms f exergy efficiency wic is expressed belw (Bejan et al., 1995) as:, VC Q E 1 C, VC C VC i, E (4. 27) 97

14 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Exergy Balance in Vapur Cmpressin-Absrptin mde Exergy balance at generatr G s s m s s m s s m G G Q 1 (4. 28) Exergy balance at cndenser s s m C - A C Q 1 (4. 29) Exergy balance at evapratr s s m E + E E Q 1 (4. 30) Exergy balance at absrber A A A Q s s m s s m s s m (4. 31) Exergy balance at cmpressr C VCA C s s m , (4. 32) Exergy balance at slutin eat excanger s s m SHE (4. 33) Exergy Efficiency e secnd law perfrmance f te system can be measured in terms f exergy efficiency wic is expressed as: VCA C i VCA C G G E E VCA Q Q,,, 1 1 (4. 34) 4.6 Results and Discussin fr Waste Ht Water Operated Hybrid System e waste t water perated ybrid system as been analyzed n te basis f energy and exergy by using Engineering Equatin Slver Sftware (Klein and Alvarad, 2012). e

15 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems numerical metd as been develped fr tree perating mdes f system and te effects f varius perfrmance parameters like rate f exergy lss in different cmpnents, exergy efficiency and COP fr cling and eating applicatins as been studied and analyzed as swn in Figures e perating parameters and cnditins used fr te cmputatin f results are indicated in able 4.1 and results btained frm develped numerical metd are given in te able 4.2. able 4.2: ermdynamic results btained frm te develped numerical metd fr waste t water perated ybrid system State Pint emperature (K) X (%NH 3 ) Pressure (bar) Specific Entalpy Exergy Rate (kw) (kj/kg) , e variatin f COP fr cling and eating applicatins alng wit exergy efficiency wit generatr temperature at different cndenser and absrber temperature fr VCA mde f peratin is swn in Figures 4.2 and 4.4 respectively. Frm figure, it is bserved tat wit an increase in generatr temperature, COP fr cling and eating applicatins initially increases and ten decreases wereas exergy efficiency decreases wit an increase in 99

16 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems generatr temperature. It is als bserved tat wit te variatin in generatr temperature fr different cndenser and absrber temperatures, iger COP and exergy efficiency can be btained at iger cndenser and absrber temperatures and tis is appening because wit an increase in generatr temperature, discarge temperature at cmpressr als increases causing te pressure rati acrss cmpressr t increase wic cnsequently increases pwer requirement leading t decrease in COP f te system at iger generatr temperature. Als, wit an increase in generatr temperature and fr iger absrber temperature, slutin circulatin rati increases cnsequently leading t an increase in generatr eat lad wic can be acieved frm eat f cndensatin f supereated vapurs exiting frm cmpressr tereby increasing te cmpressr rati acrss cmpressr wic accunts fr an increase in eat f cndensatin and cmpressr wrk and its verall effect is t reduce COP and exergy efficiency at iger generatr temperatures. e variatin f COP fr cling and eating applicatins alng wit exergy efficiency wit generatr temperature at different absrber and cndenser temperature fr VA mde f peratin is swn in Figures 4.3 and 4.4 respectively. Frm figure it is evident tat wit an increase in generatr temperature, COP fr cling and eating applicatins alng wit exergy efficiency sws a decreasing trend and is attributed t te fact tat altug increased generatr temperature prduces mre refrigerant vapurs but als prduces mre irreversibility in te system tere by reducing perfrmance f te system. Als, wit an increase in generatr temperature fr different cndenser and absrber temperatures, system pressure in generatr will increase, resulting in release f lesser ammnia vapurs frm generatr, tereby decreasing te exergy efficiency f VA mde f peratin. Hwever, it is als evident tat maximum COP fr cling and eating applicatins alng wit exergy efficiency can be btained at iger absrber and cndenser temperatures. 100

17 COP fr cling applicatins COP fr eating applicatins COP fr cling applicatins COP fr eating applicatins Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems COPcling f VCA mde (_A=_C= 25 C) COP cling f VCA mde (_A=_C= 35 C) COP cling f VCA mde (_A=_C= 45 C) COPeating f VCA mde (_A=_C= 25 C) COP eating f VCA mde (_A=_C= 35 C) COP eating f VCA mde (_A=_C= 45 C) Generatr emperature ( C) Figure 4.2: Variatin f COP f a vapur cmpressin absrptin mde wit generatr temperature at different absrber and cndenser temperature COPcling f VA mde (_A=_C= 25 C) COP cling f VA mde (_A=_C= 35 C) COP cling f VA mde (_A=_C= 45 C) COPeating f VA mde (_A=_C= 25 C) COP eating f VA mde (_A=_C= 35 C) COP eating f VA mde (_A=_C= 45 C) Generatr emperature ( C) Figure 4.3: Variatin f COP f vapur absrptin mde wit generatr temperature at different absrber and cndenser temperature 101

18 Exergy Efficiency f VA mde Exergy Efficiency f VCA mde Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems ƞψ f VA mde (_A=_C= 25 C) ƞψ f VA mde (_A=_C= 45 C) ƞψ f VCA mde (_A=_C= 35 C) ƞψ f VA mde (_A=_C= 35 C) ƞψ f VCA mde (_A=_C= 25 C) ƞψ f VCA mde (_A=_C= 45 C) Generatr emperature( C) 0.4 Figure 4.4: Variatin f exergy efficiency f vapur absrptin mde and vapur cmpressin absrptin mde wit generatr temperature at different absrber and cndenser temperature e variatin f COP fr cling and eating applicatins wit cndenser temperature at cnstant evapratr temperature fr VA, VCA and VC mde f peratin is swn in Figure 4.5. Frm figure, it can be seen tat wit an increase in cndenser temperature, COP fr cling and eating applicatins fr VC mde f peratin initially increases and ten decreases wile COP fr cling and eating applicatins sws a decreasing trend fr VCA and VA mde f peratin. e reasn fr te beaviur f COP in VC mde is due t te fact tat wit an increase in cndenser temperature, dryness fractin f liquid refrigerant at te exit frm expansin device increases wic cnsequently causes cling capacity t g dwn. is eventually increases te pressure rati acrss cmpressr wic subsequently increases te pwer cnsumed by cmpressr and terefre, bt tese factrs cause COP t decrease at iger cndenser temperatures. Hwever, fr VCA mde f peratin an increase 102

19 COP fr cling applicatins COP fr eating applicatins Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems in cndenser temperature increases te pressure rati and mass flw rate tereby decreasing te cncentratin f strng slutin wile cncentratin f weak slutin remains cnstant. is results in decrease in slutin circulatin rati and generatr eat lad causing COP t reduce at iger cndenser temperature. Als, fr VA mde f peratin, COP fr cling and eating applicatins sws a decreasing trend and is due t te reasn tat wit an increase in cndenser and absrber temperature, generatr pressure increases resulting in te release f lesser ammnia vapurs frm generatr, tereby decreasing te perfrmance f VA mde f peratin COPcling f VA mde (_G=65 C, _E=5 C) COPcling f VC mde ( _E=5 C) COPeating f VA mde (_G=65 C, _E=5 C) COPcling f VCA mde (_G=65 C, _E=5 C) COPeating f VCA mde (_G=65 C, _E=5 C) COPeating f VC mde ( _E=5 C) Cndenser emperature ( C) 0 Fig.4.5: Variatin f COP f vapur absrptin mde, vapur cmpressin absrptin mde and vapur cmpressin mde wit cndenser temperature e variatin f exergy efficiency wit cndenser temperature at cnstant evapratr temperature fr VC, VCA and VA mde f peratin is swn in Figure 4.6 and is swing te same trend f an initial increase and ten decrease in all te tree mdes f peratin. Fr 103

20 Exergy Efficiency f VCA and VA mde Exergy Efficiency f VC mde Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems VC mde f peratin tis is appening because at cnstant evapratr temperature, cling capacity and exergy efficiency at evapratr ges dwn. us, exergy efficiency f VC mde f peratin decreases wit an increase in cndenser temperature. Hwever, fr VCA mde f peratin, exergy efficiency sws trend as explained abve because f te reasn tat wit an increase in cndenser temperature, mass flw rate in te cndenser increases resulting in an increase in strng slutin cncentratin in cndenser wic eventually decreases slutin circulatin rati and irreversibility, leading t decrease in exergy efficiency f VCA mde f peratin ƞψ f VA mde (_G=65 C, _E=5 C) ƞψ f VCA mde (_G=65 C, _E=5 C) ƞψ f VC mde ( _E=5 C) Cndenser emperature ( C) 0.65 Figure 4.6: Variatin f exergy efficiency f vapur absrptin mde, vapur cmpressin absrptin mde and vapur cmpressin mde wit cndenser temperature 104

21 Wrk rate f cmpressr (kw) Exergy lss rate in cmpressr (kw) Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Als, exergy efficiency f VA mde first increases and ten decreases wit an increase in cndenser temperature because f te fact tat increase in cndenser temperatures leads t increase in generatr pressure wic result in release f less ammnia vapurs frm generatr tereby reducing irreversibility and exergy efficiency. e variatin f cmpressr wrk rate and exergy lss rate in cmpressr wit cndenser temperature fr VCA and VC mde f peratin is swn in Figure 4.7 and frm figure, it is evident tat wit an increase in cndenser temperature tere is a decrease in cmpressr wrk rate fr bt te mdes and is fund t be small in VCA mde in cmparisn t VC mde f peratin because refrigerant vapurs require lesser wrk t becme supereated. e exergy lss rate in cmpressr in VCA and VC mde decreases initially and becmes almst cnstant at iger cndenser temperatures. e decrease in exergy lss rate in te cmpressr in VC mde is iger tan VCA mde f peratin W_COMPRESSOR f VCA mde (kw) W_COMPRESSOR f VC mde (kw) Exergy lss in Cmpressr f VCA mde (_G=65 C, _E= 5 C) Exergy lss in Cmpressr f VC mde (_G=65 C, _E= 5 C) Cndenser emperature ( C) Fig.4.7: Variatin f rate f cmpressr wrk and rate f exergy lss in cmpressr f vapur cmpressin mde and vapur cmpressin absrptin mde wit cndenser temperature 105

22 COP fr cling applicatins COP fr eating applicatns Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Figure 4.8 sws te variatin f COP fr cling and eating applicatins wit evapratr temperature at cnstant cndenser temperature fr VA, VC and VCA mde f peratin and it becmes evident tat COP fr cling and eating applicatins in VC mde increases wit an increase in evapratr temperature. But fr VCA and VA mde tere is a sligt increase in COP fr cling and eating applicatins wit an increase in evapratr temperature. e beaviur f COP in VC mde is due t te reductin f cmpressr wrk as swn in Figure But fr VCA mde f peratin wit an increase in an evapratr temperature, pressure rati acrss cmpressr decreases wic decreases te cmpressr wrk as swn in Figure Hwever, in case f VA mde f peratin, an increase in evapratr temperature increases te absrber pressure, cnsequently absrptin efficiency f te strng slutin increases leading t an increase in perfrmance f te system. e waviness in te figure is due t fact tat values s btained fr COP fr VA and VCA mde are very clse t eac ter wic sw little verlapping f te symbls used in te pltting COPcling f VA mde (_G=65 C, _C=40 C) COPcling f VCA mde (_G=65 C, _C=40 C) COPcling f VC mde ( _C=40 C) COPeating f VA mde (_G=65 C, _C=40 C) COPeating f VCA mde (_G=65 C, _C=40 C) COPeating f VC mde ( _C=40 C) Evapratr emperature ( C) 0.5 Fig.4.8: Variatin f COP f vapur absrptin mde, vapur cmpressin absrptin mde and vapur cmpressin mde wit evapratr temperature 106

23 Exergy Efficiency f VCA and VA mde Exergy Efficiency f VC mde Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems e variatin f exergy efficiency wit evapratr temperature at cnstant cndenser temperature fr VA, VC and VCA mde f peratin is swn in Figure 4.9 and it can be seen tat exergy efficiency f VC mde f peratin increases wereas exergy efficiency f VCA and VA mde f peratin decreases. is is because in VC mde, an increase in evapratr temperature decreases cmpressr wrk as swn in Figure 4.10 and tis leads t decrease in exergy efficiency f te mde f peratin. e exergy efficiency f VCA mde decreases because f decrease in cmpressr wrk rate due t te reductin in cmpressin rati wic in turn decreases exergy efficiency due t te reductin in utput exergy. e exergy efficiency f VA mde sws a decreasing trend wic can be explained by secnd law f termdynamics (eq. 3.31) tat lwer evapratr temperature as a iger trust t cause cling ƞψ f VA mde (_G=65 C, _C=40 C) ƞψ f VCA mde (_G=65 C, _C=40 C) ƞψ f VC mde ( _C=40 C) Evapratr emperature ( C) 0.75 Figure 4.9: Variatin f exergy efficiency f vapur absrptin mde, vapur cmpressin absrptin mde and vapur cmpressin mde wit evapratr temperature 107

24 Wrk rate f cmpressr (kw) Exergy lss rate in cmpressr (kw) Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Figure 4.10 sws te variatin f cmpressr wrk rate and exergy lss rate in cmpressr wit evapratr temperature at cnstant cndenser temperature fr VCA and VC mde f peratin. Frm figure, it is evident tat wit an increase in evapratr temperature, tere is a decrease in cmpressr wrk rate fr bt te mdes f peratin and is small in VCA mde in cmparisn t VC mde. e exergy lss rate in VCA and VC mde sws a sligt decrease and becmes almst cnstant at iger evapratr temperatures. e decrease in exergy lss rate in VC mde is iger tan VCA mde f peratin W_COMPRESSOR f VCA mde (kw) W_COMPRESSOR f VC mde (kw) Exergy lss in Cmpressr f VCA mde (_G=65 C, _C=40 C) Exergy lss in Cmpressr f VC mde (_G=65 C, _C=40 C) Evapratr emperature ( C) 0 Figure 4.10: Variatin f rate f cmpressr wrk and rate f exergy lss in cmpressr f vapur cmpressin mde and vapur cmpressin absrptin mde wit evapratr temperature e variatin f exergy efficiency and exergy lss rate in different cmpnents wit cndenser temperature at cnstant generatr and evapratr temperature fr VA, VC and VCA mde f peratin is swn in Figure Frm figure, it is evident tat exergy efficiency fr VC mde is te igest and it is te lwest fr VCA mde f peratin. e 108

25 Exergy Efficiency f different mdes Exergy lss rate in different cmpnents (kw) Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems exergy lss rate in generatr is te igest fllwed by evapratr, cndenser and absrber. e exergy lss rate in te generatr and evapratr decreases wit an increase in cndenser temperature wereas exergy lss initially increases and ten decreases fr cndenser. is is appening because at cnstant evapratr temperature, cling capacity at evapratr ges dwn wic cnsequently lwers te exergy efficiency f evapratr. us, exergy efficiency f VC mde f peratin decreases wit an increase in cndenser temperature. Hwever, exergy efficiency fr VCA mde f peratin at iger cndenser temperature sws a decreasing trend because mass flw rate in cndenser increases resulting in an increase in strng slutin cncentratin in cndenser wic subsequently reduce te slutin circulatin rati and finally irreversibility. Hence, iger cndenser temperature leads t decrease in exergy efficiency f VCA mde f peratin. ƞψ f VA mde (_G=65 C, _E= 5 C) ƞψ f VC mde _E= 5 C Exergy lss in Absrber (_G=65 C, _E= 5 C) Exergy lss in Evapratr (_G=65 C,_E= 5 C) 0.8 ƞψ f VCA mde (_G=65 C, _E= 5 C) Exergy lss in Cndenser (_G=65 C, _E= 5 C) Exergy lss in Generatr (_G=65 C,_E= 5 C) Cndenser emperature ( C) 0 Figure 4.11: Variatin f exergy efficiency and rate f exergy lss f different cmpnents f vapur absrptin mde, vapur cmpressin mde and vapur cmpressin absrptin mde wit cndenser temperature 109

26 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Als, exergy efficiency f VA mde at iger cndenser temperature sws decreasing trend because an increase in cndenser temperature leads t an increase in generatr pressure wic result in release f less ammnia vapurs frm generatr tereby reducing irreversibility and exergy efficiency. e variatin f exergy efficiency and exergy lss rate in different cmpnents wit evapratr temperature at cnstant generatr and cndenser temperature fr VA, VC and VCA mde f peratin is swn in Figure Frm figure, it is evident tat exergy efficiency fr VC mde is te igest and it is te lwest fr VCA mde f peratin. e exergy lss rate in generatr is te igest fllwed by evapratr, cndenser and absrber. is is because in VC mde, an increase in evapratr temperature decreases te cmpressr wrk rate as swn in Figure 4.10 wic leads t reduce exergy efficiency. e exergy efficiency f VCA mde at iger evapratr temperature decreases because f drp ff in cmpressr wrk rate due t te reductin in cmpressin rati wic in turn decreases te exergy efficiency due t te reductin in utput exergy. e trend fr exergy efficiency f VA mde can be explained by secnd law f termdynamics (eq. 3.31) tat lwer evapratr temperature as a iger trust t cause cling. 110

27 Exergy Efficiency f different mdes Exergy lss rate in different cmpnents(kw) Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems ƞex f VA mde (_G=65 C, _C=40 C) ƞex f VC mde ( _C=40 C) Exergy lss in Absrber (_G=65 C, _C=40 C) Exergy lss in Evapratr (_G=65 C, _C=40 C) 0.8 ƞex f VCA mde (_G=65 C, _C=40 C) Exergy lss in Cndenser (_G=65 C, _C=40 C) Exergy lss in Generatr (_G=65 C, _C=40 C) Evapratr emperature ( C) 0 Figure 4.12: Variatin f exergy efficiency and rate f exergy lss f different cmpnents f vapur absrptin mde, vapur cmpressin mde and vapur cmpressin absrptin mde wit evapratr temperature e variatin f exergy lss rate in different cmpnents wit ambient temperature at cnstant generatr, evapratr and cndenser temperature fr VA, VC and VCA mde f peratin is swn in Fig Frm figure it is clear tat rate f exergy lss in generatr and absrber initially decreases and ten increases. e rate f exergy lss in cndenser decreases wile it increases fr evapratr wit an increase in te ambient temperature. is clearly indicates tat ambient temperature directly affect te exergy lss and is fund t be cnsistent as suggested by te autr (Bejan et al., 1995). 111

28 Exergy lss rate in different cmpnents (kw) Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Exergy lss in Cndenser (_G=65 C,_E= 5 C, _C=40 C) Exergy lss in Absrber (_G=65 C, _E= 5 C,_C=40 C) Exergy lss in Generatr (_G=65 C, _E= 5 C,_C=40 C) Exergy lss in Evapratr (_G=65 C, _E= 5 C,_C=40 C) Ambient emperature (K) Figure 4.13: Variatin f exergy lss in different cmpnents f vapur absrptin mde, vapur cmpressin mde and vapur cmpressin absrptin mde wit ambient temperature A cmparative tabular representatin f different mdes f peratin f ybrid system is swn in able System Descriptin and Wrking Principle f Bigas Operated Hybrid System e system t be analyzed is an ammnia-water vapur cmpressin-absrptin ybrid system. e water is eated in a bigas fired biler wic is being used as a eat surce t te generatr. e system as swn in Figure 4.14 cnsists f te generatr, cmpressr, cndenser, an absrber, an evapratr, slutin eat excanger, trttling device, pressure reducing valves, flw cntrlling valves ( V 1, V 2 & V 3 ) and a pump. e wrking fluid being used is a mixture f ammnia and water were ammnia is refrigerant and water is an absrbent. In te present system, cmpressr as been emplyed between te generatr and 112

29 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems cndenser as tis being an ideal place because f te availability f dry saturated vapurs at te utlet f generatr. e cmpressr increases pressure and temperature f refrigerant befre entering te cndenser and eat rejected in cndenser is utilized fr prcess applicatin wit an aim t acieve iger COP. In te present system te strng slutin is pumped frm absrber at state pint (8) trug slutin eat excanger fr extracting eat frm weak slutin exiting te generatr at state pint (3). e ammnia vapurs frmed by te eat f t water frm biler enter cmpressr at state pint (2) were temperature and pressure f refrigerant (ammnia) is raised befre entering in t te cndenser. e refrigerant vapurs are cndensed in cndenser at state pint (5) and latent eat f cndensatin is released in t te cling water being circulated trug cndenser. e liquid ammnia befre entering te evapratr is trttled trug trttling device fr reducing its pressure and temperature at state pints (5-6). At tis lw pressure, liquid ammnia canges pase after absrbing te latent eat frm circulating water being used fr space cling. e refrigerant vapurs finally enter absrber at state pint (7), tus leading t te frmatin f strng slutin in an absrber. e prcess cntinues and tere is a simultaneus prductin f cling and eating effect. e mass flw rate f water t be fed in te biler is assumed t be at cnstant temperature f 30 C. e water t be fed in te biler is eated wit te elp f bigas and same water is fed in t te generatr f te ybrid vapur cmpressin system witut any temperature lss t te surrundings. e equatins used t analyze biler are same as mentined in te equatins in capter

30 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems able 4.3: Cmparative analysis f different mdes f peratin f ybrid system Operating Cnditins Mdes f Operatin Variatin f generatr temperature Variatin f evapratr temperature Variatin f cndenser temperature Variatin f ambient temperature VA mde f peratin COP fr cling and eating applicatins as well as exergy efficiency sws a decreasing trend COP sws a sligt increase fr cling and eating applicatins wile exergy efficiency sws a decreasing trend COP fr cling and eating applicatins sws a decreasing trend wile exergy efficiency sws an initial increase and furter sws a decreasing trend e exergy efficiency sws an increasing trend wit ambient temperature VCA mde f peratin COP fr cling and eating applicatins initially increases and ten decreases wereas exergy efficiency sws a decreasing trend COP fr cling and eating applicatins sws a sligt increase wile exergy efficiency sws a decreasing trend. Again, tere is a decrease in cmpressr wrk wit evapratr temperature wic is cmparatively smaller wen cmpared t VC mde f peratin COP fr cling and eating applicatins sws a decreasing trend wile exergy efficiency sws an initial increase and furter decreasing trend. Als, tere is a decrease in cmpressr wrk wit cndenser temperature wic is fund t be small wen cmpared t VC mde f peratin e exergy efficiency remains almst cnstant wit an increase in ambient temperature VC mde f peratin - COP fr cling and eating applicatins alng wit exergy efficiency increases wit an increase in evapratr temperature COP fr cling and eating applicatins alng wit exergy efficiency sws an initially increase and ten decreasing trend. Als, tere is a decrease in cmpressr wrk wit increasing cndenser temperature e exergy efficiency sws an increasing trend wit ambient temperature 114

31 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Bigas feed Cld water in BOILER Ht water inlet t Generatr Ht water utlet f Generatr Q G GENERAOR COMPRESSOR V 2 V Q CONDENSER C HEA EXCHANGER 10 9 Pump 8 11 PR- VALVE rttling valve 6 ABSORBER V 1 EVAPORAOR Q A 7 Q E Figure 4.14: A scematic line diagram f a bigas pwered ammnia-water ybrid (VCA) system 4.8 ermdynamic Analysis f Bigas Operated Hybrid System e system as been analyzed n te basis f exergy and energy by develping a numerical mdel using EES (Klein and Alvarad, 2012). e numerical mdel as been 115

32 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems develped t study te effects f varius perfrmance parameters like COP fr cling and eating applicatins, exergy efficiency and exergy lss rates in different cmpnents. e perating parameters and cnditins used fr te cmputatin f results are indicated in able 4.4 and results btained frm te develped numerical metd using assumptins mentined in sectin 4.3 are given in able 4.5. In te develped numerical metd, input parameters are taken as E = 5 C, G = 65 C & C = A = 30 C. e termdynamic analysis f bigas perated vapur cmpressin-absrptin ybrid system invlves energy and exergy balance equatins f different cmpnents based n varius assumptins as listed abve in sectin 4.3 and parameters given in able 4.4. e energy balance equatins f different cmpnents are same as mentined abve in subsectin Hwever, varius exergy balance equatins f different cmpnents are same as mentined abve in subsectin Results and Discussins fr Bigas Operated Hybrid System e analyzed system as been evaluated n te basis f exergy and energy t study te effects f varius perfrmance parameters like COP fr cling and eating applicatins, exergy efficiency and rate f exergy lss in different cmpnents. e different results btained frm evaluatin are presented in te Figures Figure 4.15 presents variatin f vlume flw rate f bigas and wrk rate f cmpressr at different generatr temperatures. As, it becmes evident frm figure, tat wit an increase in generatr temperature, vlume flw rate f gas in te biler t eat water als increases and reaces upt 4.42 m 3 /r fr attaining generatr temperature f 130 C. is is mainly because f te fact tat energy required t attain a temperature f 130 C is mre and tus bigas requirement als increases. Hwever, cmpressr wrk rate sws a decreasing 116

33 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems trend wit an increase in generatr temperature and tis is attributed t te reduced difference in pressure and temperature at te entry and exit f cmpressr. able 4.4: Operating cnditins and fixed parameters used in te analysis f bigas perated ybrid system Operating parameters Cling capacity Generatr pressure Evapratr pressure Generatr temperature, G Evapratr temperature, E Cndenser temperature, C Absrber temperature, A Fixed values 1R 12 bar 2 bar K K K K Mass flw rate f strng slutin ( m 1) kg/s Mass flw rate f refrigerant ( m 2 ) kg/s Mass flw rate f weak slutin ( m 3 ) kg/s Ambient temperature, Ambient pressure emperature f water fed in t te biler Calrific value f bigas (btained frm cw dung) K 1 bar 30 C kj/m 3 (ttp://mnre.gv.in/file-manager) 117

34 Vlume flw rate f bigas (m 3 /r) Wrk rate f cmpressr (kw) Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems able 4.5: ermdynamic results btained frm te develped numerical metd fr State Pint bigas perated ybrid system ( E = -5 C, A = C = 30 C & G = 65 C) emperature (K) X(%NH 3 ) Pressure(bar) Specific Entalpy (kj/kg) Exergy Rate (kw) Vlume flw rate f bigas (m3/r) Wrk rate f cmpressr (kw) Generatr emperature ( C) 0.05 Figure 4.15: Variatin f vlume flw rate f bigas and wrk rate f cmpressr wit generatr temperature 118

35 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems Figure 4.16 depicts te variatin f COP and exergy efficiency wit generatr temperature and bt te parameters sws a decreasing trend wit an increase in generatr temperature. Frm figure, it can be seen tat wit an increase in generatr temperature COP fr bt cling and eating applicatins decreases and reaces up t 0.11 and 1.11 respectively at generatr temperature f 130 C. Hwever, COP fr eating applicatins at 110 C sws a peak value f and tis may be due t te fact tat tere is a significant decrease in cmpressr wrk wit an appreciable increase in ' Q G '. Hwever, suc trends can be nrmalized by using quantitative tecniques. e exergy efficiency als sws a decreasing trend wit an increase in generatr temperature and reaces upt 0.04 at 130 C. is is appening because wit an increase in generatr temperature, slutin circulatin rati increases, cnsequently increasing te generatr eat lad. is increase in generatr eat lad reduces te cmpressr wrk marginally but eat f cndensatin still increases and te verall effect is t reduce COP and exergy efficiency at iger generatr temperatures. e variatin f COP and exergy efficiency wit evapratr temperature is swn in Figure 4.17 and it can be seen frm figure, tat wit an increase in evapratr temperature, COP fr cling and eating applicatins increases and reaces up t 0.21 and respectively, at an evapratr temperature f 10 C. e beaviur f exergy efficiency wit an increasing evapratr temperature sws a decreasing trend wit a value f 0.09 at 10 C and tis is because wit an increase in evapratr temperature, pressure rati acrss te cmpressr decreases tus reducing te cmpressr wrk. is decrease in cmpressr wrk eventually reduces te ttal energy input required and terefre, imprves COP f te system. e variatin in exergy efficiency is attributed t majr cange bserved in numeratr part f te eq. (4.34). 119

36 COP Exergy Efficiency COP Exergy Efficiency Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems COPcling f VCA mde (_A=_C= 30 C, _E= -5 C) COPeating f VCA mde (_A=_C= 30 C, _E= -5 C) ƞψ f VCA mde (_A=_C= 30 C, _E= -5 C) Generatr emperature ( C) 0 Figure 4.16: Variatin f COP (cling and eating) and exergy efficiency wit generatr temperature 1.2 COPcling f VCA mde (_A=_C= 30 C, _G= 65 C) COPeating f VCA mde (_A=_C= 30 C, _G= 65 C) ƞψ f VCA mde (_A=_C= 30 C, _G= 65 C) Evapratr emperature ( C) 0 Figure 4.17: Variatin f COP (cling and eating) and exergy efficiency wit evapratr temperature 120

37 COP Exergy Efficiency Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems e variatin f COP and exergy efficiency wit absrber and cndenser temperature is swn in Figure 4.18 and it can be seen frm figure, tat wit an increase in absrber and cndenser temperature, COP fr cling applicatins initially decreases and reac up t at 30 C, but wit furter increase in absrber and cndenser temperature COP fr cling applicatins sws an increasing trend, wile COP fr eating applicatins initially decreases and reac up t at 30 C, but wit furter increase in absrber and cndenser temperature, COP fr eating applicatins sws an increasing trend. e range f COP fr bt te applicatins ver te entire variatin f absrber and cndenser temperatures is marginal and sws cnsistency f te system COPcling f VCA mde (_E= -5 C, _G= 65 C) COPeating f VCA mde (_E= -5 C, _G= 65 C) ƞψ f VCA mde (_E= -5 C, _G= 65 C) Absrber and Cndenser emperature ( C) 0.18 Figure 4.18: Variatin f COP (cling and eating) and exergy efficiency wit absrber and cndenser temperature e exergy efficiency als sws a decreasing trend upt 30 C and wit furter increase in absrber and cndenser temperature it sws an increasing trend. e abve beaviur f exergy efficiency is attributed t an increase in cndenser and absrber 121

38 Vapur Cmpressin-Absrptin Hybrid Refrigeratin Systems temperature as pressure rati increases leading t an increase in mass flw rate subsequently decreasing te cncentratin f strng slutin wile cncentratin f weak slutin remains cnstant. is results in decrease in slutin circulatin rati and generatr eat lad causing COP t reduce. e variatin f exergy lss rate in different cmpnents and exergy efficiency wit ambient temperature is swn in Figure Frm figure, it is clear tat exergy lss rate in te generatr and cndenser sws a decreasing trend upt te ambient temperature f 313K and 305K respectively and ten increases. is sws peratinal pint f te system wit minimum exergy lss rate witin tis range f ambient temperature as tese cmpnents cntribute t maximum lsses. e exergy lss rate in cmpressr als sws a decreasing trend wit an increase in ambient temperature. Hwever, exergy lss rate in absrber and evapratr sws an increasing trend wit an increase in ambient temperature. e exergy efficiency sws an increasing trend wit an increase in ambient temperature and tis is attributed t termdynamic beaviur f te system. e termdynamic imperfectin can be quantified as exergy destructin, wic represents lsses in energy quality r usefulness. 122