V.C. Mei and F.C. Chen

Transcription

1 ORNUCON-38 EXPERMENTAL ANALYSS OF A WNDOW AR CONDTONER WTH R-22 AND ZEOTROPC MXTUFW OF R-32/125/134 VC Mei nd FC Chen nd J Crlstcdt nd DHlldcn, Energy Rencwblc nd Rcscrch Section Encrgy Division Ok Ridgc Ntionl Lbortory August 15 Prcprcd for the US Dcprtrncnt of Encrgy nd E L DuPont Dc Ncmours, Co nc Preprcxi by OAK RDGE NATONAL LABORATORY Ok Ridgc, Tennessee mngcd by MARTLN MARET A ENERGY SYSEMS, NC for the US DEPARTMENT OF ENERGY undcr con trct DE-AC05-840R21400

2 This report hs been reproduced directly from the best vilble copy Avilble to DOE nd DOE contrctors from the Office of Scientific nd Technicl nformtion, PO Box 62 Ok Ridge, TN 37831; prices vilble from (615) , FTS Avilble to the public from the Ntionl Technicl nformtion Service, US Deprtment of Commerco, 5285 Port Royl Rd Springfield, VA ~ This report ws prepred s n ccount of work sponsored by n gency of the United Sttes Government Neither the United Sttes Government nor ny gency thereof, nor ny of their employees mkes ny wrrnty, express or implied, or ssumes ny legl libility or responsibility for the ccurcy, completeness, or usefulness of ny informtion, pprtus, product or procss disclosed, or represents tht its use would not infringe privtely owned rights Reference herein to ny specific commercil product, process or service by trde nme, trdemrk, mnufcturer, or otherwise, does not necessrily constitute or impiy its endorsemen:, recommendtion, or fvoring by the United Sttes Government or ny gency therereof The views nd opinions of uthors expressed herein do not necessrily stte or reflect those of the United Sttes Govemmcint or ny gency thereof

3 DSCLAMER Portions of this document my be illegible in electronic imge products mges re produced from the best vilble originl document

4 EXPEMMENTAL ANALYSS OF A WNDOW AR CONDTONER WTH R-22AND ZEOTROPC MXTURE OF R-32/125/134 V-C Mei nd FC Chen nd J Crktedt nd D Hllden' Energy Renewble nd Reserch Section Energy Division Ok Ridge Ntionl Lbortory August 1% Prepred for the US Deprtment of Energy nd E L DuPont de Nemours, Co nc prepred by OAK RDGE NATLONAL LABORATORY Ok Ridge, Tennessee ged by MARTN MARETAENERGY SY!TEMS,NC for the USDEPARTMENT OF ENERGY under mtrct D E - A ~ O R On lon from the Deprtment of Applied Thermodynmics nd Refrigertion, Royl nstitute of Technology,Sweden

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6 TABLE OF CONTENTS USTOF FGURES ABSTRACT ACKNOWLEDGMENTS v vii ix 1 NTRODUCTON 1 2 TESTSETUP 2 3 TEST PROCEDURES 7 4 TESTRESULTS 41 HEAT EXCHANGER Circuit TEMPERATURE DSTRBUTON 411 Evportor Circuit Temperture Distribution 412 Condenser Circuit Temperture Distribution EVAPORATOR HEAT EXCHANGER CAPACTY COMPRESSOR PERFORMANCE Compressor Dischrge Pressure Compressor Dischrge Temperture Compressor High-Low Pressure Rtio Refrigernt Mss Flow Rte Compressor Power Consumption 22 5 DSCUSSONS AND CONCLUSONS 24 6 RECOMMENDATONS FOR FUTURE WORK 26 7 REFERENCES 27 iii

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8 LST OF FGURES Fig 1 Evportor het exchnger 3 Fig 2 Condenser het exchnger 4 Fig 4 5 Test setup in environmentl chmber 6 Fig 3 Fig 5 Schemtic of test rig setup Evportor het exchnger top circuit temperture distribution-r22 nonfloodedcoils 10 Fig 6 Evportor het exchnger top circuit temperture distribution-ternry mixture nonflooded coils 10 Fig 7 Evportor het exchnger top circuit temperture distribution-r22 floodedcoils 11 Fig 8 Fig Fig 10 Fig 11 Fig 12 Fig 13 Fig 14 Evportor het exchnger top circuit temperture distributiowternry 11 mixture flooded coils Condenser het exchnger top circuit temperture distributionr22 13 nonflooded coils Condenser het exchnger top circuit temperture distribution-ternry mixture nonflooded coils 13 Condenser het exchnger top circuit temperture distribution-r22 floodedcoils 14 Condenser het exchnger top distribution-ternry mixture flooded coils circuit temperture 14 Evportor het exchnger cooling cpcity s function of outdoor 16 temperture Compressor dischrger pressure s function of outdoor 17 temperture Fig 15 Compressor dischrger temperture s function of outdoor temperture 1 Fig 16 Compressor high-low pressure rtio s function of outdoor temperture 20 Fig? Refrigernt mss flow rte s function of outdoor temperture 21 V

9 Fig 18 compressor power consumption s function of outdoor temperture 23 Fig 1 System COP s function of outdoor temperture 24 vi c

10 This study is the result of the coopertive reserch nd development greement (CRADA) between Ok Ridge Ntionl Lbortory nd E Du Pont De Nemours nd Compny, nc, (CRADA No ) for testing the use of het exchngers s the evportor nd condenser in n ir-conditioning rig Het exchngers t typicl relistic operting conditions were tested with R-22 nd with its potentil replcement, ternry mixture of R-32(30%)/R- 125(10%)/R-l34(60%) A test rig ws built tht provided for opertion of the lowtemperture exchnger (evportor) with flooded coils The test results indicted tht the performnce of the evportor het exchnger using ternry mixture, in terms of cooling cpcity, would be round 74% less thn the performnce using R-22 The cooling cpcity for both refrigernts improved with flooded evportor opertion by 86% for R-22 nd by 15% for ternry mixture Compred with R-22 opertion, opertion with ternry mixture results in slightly higher compressor dischrge pressure, lower compressor dischrge temperture, slightly lower compressor power consumption, nd higher compressor high-low pressure rtio Temperture glide for ternry mixture, for both evportor nd condenser, ws clerly evident, but not s pronounced s expected becuse of the pressure drop (nd thus the temperture drop) long the coils Further improvement of the performnce of ternry mixture is possible if the evportor is rrnged in counter-cross-flow configurtion to tke dvntge of the temperture glide Current evportor designs re mostly concurrent-cross-flow, which is more pproprite for single-component refrigernts or zeotropic refrigernt mixtures vii

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12 ACKNOWLEDGMEN?S The uthors would like to thnk Dr D Bivens of Du Pont for providing us with the ternry refrigernt mixture nd for reviewing of the test rig design nd test results The uthors would like to thnk Mr J Nelson of Refrigertion Reserch, nc, for providing us the ccumultor-het exchnger used in our test setup This project ws jointly sponsored by E Du Pont De Nemours & Co nd the USDeprtment of Energy Ok Ridge Ntionl Lbortory is mnged by the Lockheed Mrtin Energy System nc under contrct DEACO5-840R21400with the USDeprtment of Energy ix

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14 1 NTRODUClON The Montrel Protocol clled for the grdul phseout of ll chlorofluorocrbon fluids (CFCs) to protect the strtospheric ozone lyer The London Amendments to the Protocol nd the US Clen Air Act clled for the eventul totl phseout of CFCs nd hydrochlorofluorocrbon fluids (HCFCs) R-22 is one of the most widely used HCFCs for pplictions such s residentil room ir conditioners, het pumps, nd supermrket refrigertion systems While much work hs been done to identify replcements for R-11 nd R-12, reltively little experimentl work with off-the-shelf het exchngers hs been done to identify replcement for R-22 in residentil ir conditioning nd het pump pplictions Rdermcher nd Jung (13) theoreticlly nlyzed the performnce of severl R-22 replcements, but ternry mixture ws not one of them Fischer nd Snd (13) screened potentil R-22 replcements Their modeling effort indicted tht ternry mixtures could hve n increse of up to 4% in the coefficient of performnce (COP) nd slightly reduced cpcity They lso mentioned tht with chnge in the composition of three refrigernts, the cpcity could be incresed by up to 20% Domnski nd Didion (13) evluted R-22 lterntives thermodynmiclly Among their findings, using R-22 performnce s the bseline dt, re tht ternry mixture [R-32(30%)/R-125(10%)/R-l34(60%)] hs lmost identicl cpcities nd COP, but higher dischrge pressures nd lower dischrge tempertures This mixture hs been regrded s one of the most likely R-22replcements; however, little experimentl work with prcticl het exchnger configurtion used on spce conditioning equipment nd operting conditions is vilble in the public domin A coopertive reserch nd development greement (CRADA) ws estblished between E Du Pont De Nemours nd Compny, nc, nd Ok Ridge Ntionl Lbortory (ORNL) in July 13 for het exchnger testing The het exchngers serve s the condenser nd evportor for ir conditioning pplictions, using R-22nd the ternry mixture The purpose of this study is to experimentlly nlyze the performnce of the mixture, tested under nerdrop-in sitution with off-the-shelf het exchngers, nd compre it with the results of tests using R-22 n this study, only refrigernt-side tests were performed The results indicted tht the Performnce of the ternry mixture is less thn tht of R-22 by 74% drop in het exchnging cpcity t 5 F mbient However, when the evportor coil is flooded, the improvement of the ternry mixture performnce is more thn tht of R-22 performnce The performnce of ternry mixture is improved to within less thn 2% to tht of R-22 1

15 2 TESTSEXUP The test setup includes het exchnger s the evportor, nother het exchnger s the condenser, nd compressor Cpillry tubes re used s n expnsion device connected to the inlet of the evportor Figures 1 nd 2 shows the het exchngers tested The evportor het exchnger is composed of four circuits Thermocouples re instlled on ech circuit The top circuit hs more thermocouples thn the other three becuse, judging from the ir movement, the top circuit will probbly be the most efficient section of the evportor However, the detiled temperture mesurement on one circuit still only provides generl picture of the het exchnger performnce The condenser het exchnger is composed of four rows but only two circuits Only one circuit hs thermocouples on it becuse the performnce should be firly even with only two circuits Figures 3 nd 4 show the schemtic of the test rig nd the rrngement of the rig in the chmbers Figure 3 shows n ccumultorhet exchnger (AHX) incorported in the test loop with refrigernt chrge of 041 lb For flooded evportor tests, dditionl refrigernt (044 lb) is chrged into the test loop until low-pressure refrigernt ccumultes in the AHX (Mei nd Chen, 14) Wrm, high-pressure refrigernt from the condenser flows through the het exchnger coil in the AHX nd boils the low-pressure refrigernt in the AHX The het exchnge in the AHX cools the high-pressure refrigernt nd results in high level of refrigernt subcooling before the refrigernt reches the expnsion devices (4 cpillry tubes in this study) Becuse the refrigernt enters the evportor in highly subcooled condition, the refrigernt is not ll evported in the evportor coils Two-phse refrigernt from the evportor exit flows to the AHX The liquid is trpped in the AHX to be boiled off by the wrm liquid from the condenser flowing through the het exchnger coil in the AHX The AHX thus provides flooded evportor coil opertion without liquid slugging bck to the compressor The refrigernt volumetric flow rte is mesured by turbine flow meter The pressures re mesured by five pressure trnsducers All the tempertures re mesured with type T thermocouples Their loctions re shown in Fig 3 2

16 AR FLOW -----c - t 'x - i s Fig 1 Evportor het exchnger 3

17 , -, AR FLOW d Fig 2 Condenser het exchnger 4

18 VOLUME FLOWDEVCE 't T ACWMUAmR- HEATEXCHANGW P 6T EVAPORATOR Fig 3 Schemtic of test rig setup 5

19 Room ir temp sensor 0 Room ir temp sensor Condenser Liquid Over Feeder Fig 4 Test setup in environmentl chmber 6

20 3 TESTPROCEDURES The tests were for two different types of refrigernts, R-22 nd the ternry mixture The evportor het exchnger ws operted t nonflooded nd flooded conditions The indoor chmber conditions were mintined t 80 F nd 52% RH; the outdoor chmber reltive humidity ws set t 27%; nd temperture, which simultes the mbient temperture, ws vried from 80 Fto 120 F For nonflooded het exchnger opertion, the mximum outdoor chmber temperture ws set t 110 F becuse of the excessive compressor dischrge pressure All tests were performed t stedy stte operting conditions Tble 1 is the test mtrix for R-22 nd ternry mixture Tble 1 Het exchnger test mtrix for R-22 nd ternry mixture Chmber temperture, ndoor 'F - Chmber reltive humidity, % Outdoor ndoor Outdoor Nonflooded coil tests Flooded coil tests Remrks ' 41 lb of refrigernt chrge for non-flooded coil tests An The test procedures were bsiclly the sme for both refrigernts, except the procedure for the system clening during the chnge of one refrigernt to the other 1 The indoor chmber ws set t 80F nd 52% RH 2 The units were tested t outdoor chmber tempertures from 80'F to 120 F, with n increment of 5"F, for both refrigernts with flooded coil opertion t ws found tht when the evportor coils were flooded, the compressor dischrge pressure becme lower For conventionl system opertion (nonflooded coils), the highest outdoor chmber temperture ws set t 110 F to void excessively high dischrge pressure 3 For flooded coil tests, the het exchnge coil inside the ccumultor ws ctivted 7

21 3 For flooded coil tests, the het exchnge coil inside the ccumultor ws ctivted Additionl refrigernt ws chrged into the unit until the output dt indicted the vpor superhet ws gone 4 When the refrigernt ws chnged from R-22 to ternry mixture, the following procedures were followed: A The system ws evcuted B The compressor ws cut out nd the oil drined New ester-bsed oil ws dded nd the compressor ws turned on for minute or so The oil ws gin drined New ester-bsed oil ws gin chrged, nd the compressor ws reconnected to the system 8

22 The test results cn be divided into severl groups-het exchnger coil temperture distribution, het exchnger performnce, nd component performnce, prticulrly compressor performnce HEATEXCHANGER COL TEMPERATURE DST UBUTON Evportor coil Temperture Distri'bution 4111 Nonflooded coil Temperture Distrr'bution Figures 5 nd 6 show the evportor top circuit temperture distribution s function of the mbient temperture for R-22 nd ternry mixture, respectively, under nonflooded coil conditions n R-22 opertion, the temperture decreses long the circuit becuse of the pressure drop At lower mbient conditions, 85 F nd %OF, the temperture t less thn hlf of the coil length strts to increse shrply This indictes the refrigernt is dried out At higher mbient tempertures, the drying out is delyed to 8/14 of the circuit length At lower mbient tempertures, the condenser het exchnger performnce improves, resulting in lower compressor dischrge pressure, which in turn, results in lower mss flow rte Tht is why refrigernt dries out more quickly t lower mbient tempertures Generlly, higher mbient temperture results in higher refrigernt temperture n this test, 5 F mbient temperture rise will increse the coil temperture by bout 3 F for most of the circuit length At the coil exit, the temperture differences re nrrowed to only 5 F for ll mbient conditions This is becuse the circuit is dried out t the exit nd the refrigernt temperture is close to ir temperture For ternry mixture opertion, s shown in Fig 6, the temperture long the circuit increses insted of decresing, even with pressure drop long the coil, for the section before refrigernt dry-out The mximum temperture glide is bout 65"F The refrigernt inlet temperture is lower thn tht for R-22 opertion At round 6/14 of the circuit length, the ternry mixture temperture becomes higher thn R-22 coil temperture The coil exit temperture of ternry mixture is round 5 to 7 F higher thn tht of R Flooded Coii Temperture Distn'bution Figures 7 nd 8 show the R-22 nd ternry mixture evportor top circuit temperture distribution with flooded coil opertion The dry-out region is lmost ll gone, except ner the exit where the refrigernt temperture increses shrply This is good indiction tht the refrigernt flows in the four evportor circuits re not evenly distributed, becuse the refrigernt temperture mesured fter the point where ll four circuits merge is lower thn the exit tempertures shown in the figures Tht mens tht some evportor circuits re flooded nd some re not The exit tempertures t different mbient conditions re not pproching ech other s in the nonflooded test The figures show tht ternry mixture refrigernt tempertures re ctully lower thn those of R-22 for most of the top circuit length

23 temperture rtio of evportor length 80/85 80/ /100 80/105 lndoortemp/outdoorternp Fig 5 Evportor top circuit temperture distributionr-22, nonflooded coils temperture M /14 2/14 3/14 4/14 5/ /14 7/14 6/14 /14 l /14 14/14 rtio of evportor length 80/0 BOB5 8O/lOO 80/105 &---& indoortemp/ou!doorternp Fig 6 - Evportor top circuit temperture distributionternry mixture, nonflooded coils 10

24 temperture 1/14 rf) 2/14 3/14 4/14 5/14 Sol85 6/14 7/14 8/14 /14 rtio of evportor length 80/ /14 12/14 13/14 14/14 80/5 80/100 80/105 indoorternp/outdoorternp Fig 7 Evportor top circuit temperture distributionr-22, flooded coils temperture FF) /14 2/14 3/14 4/14 5/14 6/14 7/14 8/14 /14 rtio of evportor length /14 12/14 13/14 14/ / /100 80/ && indoortemp/ovtdoortemp Fig 8 Evportor top circuit temperture distributionternry mixture, flooded coils 11

25 This indictes tht flooded evportor probbly enhnces circuit performnce more for the ternry mixture thn for R-22 The temperture glide OF round 4 F for the ternry mixture is clerly shown in Fig 8 The concurrent-cross-flow evportor het exchnger design is suitble for single refrigernt ppliction where refrigernt temperture becomes lower becuse of the pressure drop long the coil The sme rrngement works ginst non-zeotropic refrigernt mixtures such s the ternry mixture tested While the ir is being cooled down, the coil temperture keeps incresing becuse of the temperture glide, even with the pressure drop long the coil f the evportor het exchnger is counter-cross-flow, the performnce of this mixture should improve nd the rnge of temperture glide should be extended 412 Condenser coil Temperture Distribution 4121 N o d d e d coil Temperture DiStn'bUton Figures nd 10 chrt the tempertures long the condenser coil s Function of mbient temperture for R-22nd the ternry mixture, respectively The condenser coil rrngement is in counter-cross-flow form between ir nd refrigernt For R-22, the coil tempertures clerly indicte the three condenser regions: superheted region, up to 8/58 of the coil; two-phse region, from 8/58 to 40/58 of the coil; nd subcooled region for the rest of the coil For the ternry mixture, the profile of the coil tempertures is similr; but becuse of the temperture glide, we re not sure where the subcooling region strts The mixture hs lower coil temperture thn does R-22 t ll mbient tempertures 4122 Flooded coil Temperture Distribution Figures 11 nd 12 show the tempertures long the top condenser circuit under flooded conditions The inlet temperture is gretly reduced This is becuse the vpor refrigernt t the compressor inlet is constntly t or ner sturted condition with little or no superhet when the evportor coil is flooded n turn, the compressor dischrge temperture becomes lower However, the exit temperture seems higher The reson could be the increse in mss flow rte for flooded coil opertion With lower compressor dischrge temperture but higher mss flow rte, it is not surprising tht the refrigernt t the condenser exit hs higher temperture thn in the nonflooded coil opertion The temperture glide for the ternry mixture is smll f the temperture profiles shown in the figures re compred, the R-22two-phse region of the circuit from 20/58 to 40/58 hs temperture drop of only bout 1or 2" But the drop is round 4 F for the mixture The concurrent-cross-flow coil rrngement will help the system performnce with the mixture However, becuse most het exchngers for condenser ppliction hve only two circuits, coil rrngement will probbly hve limited influence on the condenser performnce 12

26 temperturr (T) Fig Condenser top circuit temperture distribution- R-22, nonflooded coils Fig 10 Condenser top circuit temperture distributionternry mixture, nonflooded coils 13

27 temperture (T) ) (( ~""-'-" rtio of condenser length Olso WtS & indooflemp/ooutdooftemp Fig 11 Condenser top circuit temperture distributionr-22, flooded coils - temperture (T) ,,, 120 -!,, loo L 4/58 16/ /58 ruo of condenser length 80/30 80/5 W/100 ~ &---& 52/58 w58 / l ~ indoorlernp/outdoortemp Fig 12 Condenser top circuit temperture dktributionternry mixture, flooded coils 14

28 42 EVAPORATOR HEAT EXCHANGER CAPACTY The mount of het exchnge is clculted from the mesured refrigernt temperture nd pressure t the inlet nd exit of the exchnger for the nonflooded coil test The enthlpy difference times the mss flow rte is the cooling cpcity For flooded-coil tests, refrigernt t the evportor exit is two-phse, nd the enthlpy t tht point cnnot be determined Additionl temperture mesurements re needed to clculte the refrigernt enthlpy t the compressor inlet, nd then subtrct the het bsorbed by the wrm refrigernt liquid from the condenser flow through the het exchnger coil in the ccumultor Figure 13 shows the evportor het exchnger cooling cpcity s function of mbient temperture Cpcities drop s the mbient temperture increses The ternry mixture in nonflooded coil test hs the lowest cooling cpcity At 5 F mbient nd nonflooded coil conditions, the mixture s cooling cpcity is bout 100 Btuk lower thn tht of R-22, bout 75% reduction However, t the sme mbient temperture but with flooded coil, the cooling cpcities of the ternry mixture nd R-22 differ by only 500 Btuk (less thn 2% cpcity penlty) The mixture t flooded coil condition outperforms R-22 t nonflooded opertion by over 1500 Btuk n the nonflooded coil test t 5 F mbient the mixture hs cooling cpcity of round 23,100 Btuk However, once the coil is flooded, the cpcity t the sme mbient jumps to 26,600 Btuh, n increse in cooling cpcity of 3500 Btuk, 15% improvement For R-22 t the sme mbient, the cooling cpcity increse of flooded coil over nonflooded coil opertion is bout 2100 Btuh, or n 84% improvement t is cler tht flooded coil opertion hs more effect on the mixture thn on R COMPRESSORPEXFORMANCE The compressor performnce is clculted from refrigernt-side mesurements of the compressor suction nd dischrge tempertures nd pressures, nd of the refrigernt mss flow rte Compressor power consumption is mesured directly from wtt mter 431 Compressor Dischrge Pressure Figure 14 shows the compressor dischrge pressure s function of the outdoor temperture for R-22 nd the mixture The dischrge pressures for R-22 re lower thn those of the mixture The differences become greter when the mbient ir temperture is higher At 80 F, the refrigernts hve the sme dischrge pressures, except for the mixture t flooded coil condition, which is bout 15 psi higher At 5 F mbient, the pressure differences become more pprent The mixture s pressure is round 6 psi higher thn R-22 in nonflooded coil opertion For flooded coil condition, R-22 dischrge pressure ctully decreses by 6 psi over nonflooded coil opertion However, the mixture dischrge pressure for flooded coil condition is even higher thn for nonflooded coil condition by bout 3 psi At 120 F mbient nd flooded coil opertion, the dischrge pressure of the mixture is lmost 40 psi higher thn tht of R-22 The reson tht the mixture hs higher pressure t flooded coil opertion could be explined this wy: the het exchnge coil in the AHX is boiling off 15

29 RWNO Lor ZLL - t 70 ~ L 20 Outdoor Temperture (OF) Fig 13 Evportor cooling cpcity s function of outdoor temperture 1 130

30 Outdoor Temperture (OF) Fig 14 Compressor dischrge pressure s function of outdoor temperture

31 refrigernt R-32 nd R-125 first becuse these compounds of the ternry mixture hve lower boiling points thn R-134 The net result would be tht t flooded coil opertion, the compressor is ctully circulting mixed refrigernt tht is richer in R-32 nd R-125, nd thus hs higher dischrge pressure nd higher system cooling cpcity 432 Compressor Dischrge Temperture Figure 15 shows the compressor dischrge temperture s function of mbient temperture The mixture hs lower dischrge temperture thn R-22 With nonflooded coil, the temperture of R-22is bout 1 F higher thn tht of the mixture t 5 F mbient With flooded coils,the difference t the sme mbient is lso bout 1 F The difference becomes greter t higher mbient temperture 433 Compressor igh-lmpressure Rtio The compressor dischrge pressure nd temperture usully do not give the compressor performnce completely But the compressor high-low pressure rtio for certin refrigernt usully indictes the compressor operting efficiency: the lower the rtio, the higher the compressor operting efficiency Figure 16shows the compressor high-low pressure rtios of R-22nd the mixture for both nonflooded nd flooded coil opertions The flooded coil opertions hve lower pressure rtios for both refrigernts: 13% lower for R-22 nd 11% lower for the mixture While the mixture hs higher rtio thn R-22,tht does not necessrily men tht the compressor is more efficient with R-22 The thermodynmic properties of the refrigernts hve to be considered, together with the compressor power input Then the compressor performnce of different refrigernts cn be determined nd compred 434 MssFlowRte Figure 17 shows the mss flow rte s function of mbient temperture The mss flow rtes for flooded coil opertion re much higher thn for nonflooded coil condition Under flooded coil opertion, the compressor constntly hs sturted, or ner sturted, suction inlet conditions, nd thus hs higher mss flow rte The mss flow rte for R-22 is bout 60 lbh, or 164%, higher thn tht of the mixture t 5 F mbient with nonflooded coils, nd the difference is consistent over the entire test rnge For flooded coil opertion, the mixture mss flow rte increses more thn tht of R-22 The difference reduces to 40 lb/h t 5 F mbient The difference becomes smller when the mbient temperture increses This is n indiction tht flooded coil opertion ids the performnce of the mixture more thn tht of R-22 in terms of mss flow rte Higher mss flow rte mens higher refrigernt-side het trnsfer coefficient nd potentilly higher cooling cpcity

32 \ : :\ 1 8 L e e3?- : 0 F F 0 0 l- 8 8 e e b e e 0 # L b b 1 b b 8 F 1 e b

33 42 1 i i /J 1 - e - A - - t 70 / 80 A22lOLoF +AWLOF %lernaav MXTUAVNo LOF L TERNAFY MlXWAULoF Outdoor Temperture (OF) Fig 16 Compressor high-low pressure rtio s function of outdoor temperture

34 - e e ' L, e 0 v e 8 rz 8 \ e e e e e e F e 0 - e r d

35 435 Compressor Power Consumption Figure 18 shows the system power consumption s function of mbient temperture Generlly, the higher the mbient temperture, the higher the system power consumption becuse of higher mss flow rte nd higher compressor dischrge pressure t is interesting to compre flooded coil nd nonflooded coil opertions For R-22, the power consumption is lmost identicl for mbient temperture up to 100 F regrdless of whether the coils re flooded, even though the flooded coil opertion will produce over 12% more mss flow rte t 5 F mbient (see Fig 17) For the mixture, flooded coil opertion consumes slightly over 4% more power thn nonflooded coil opertion, while the mss flow rte for the f l d e d coil increses by more thn 20% over the nonflooded coil When the coil is flooded, the compressor dischrge temperture becomes lower, which often implies less compressor power consumption However, becuse of the increse of refrigernt mss flow rte, the compressor power consumption should increse The two fctors work ginst ech other, resulting in higher mss flow rte for flooded coil opertion without incresing compressor power in the sme proportion 436, System Coefficient of Performnce (COP) Figure 1 shows the system COPSs function of outdoor temperture for LOF nd bseline opertions At 5 F mbient, the COP for the ternry mixture is bout 74% nd 25% less thn the COP for R-22 during bseline nd LOF opertions, respectively LOF opertion enhnces the performnce of the ternry mixture more thn tht of R-22 COP is improved by 68% for R-22 nd by 7% for the ternry mixture over bseline opertion 22

36 8' 3 Power Consumption (xi000 Btu/h)

37 Rnmo L W RWLOF XRNARY MXTURONO COS TERNARY MXNAEAOF b Outdoor Temperture (OF) Fig 1 System COP s function of outdoor temperture c

38 5 DSCUSONS AND CONCLUSONS Two het exchngers, one used s n evportor nd the other used s condenser, were extensively tested using R-22 nd ternry mixture of R-32/R-125/R-l34 t nonflooded nd flooded evportor conditions The test results cn be summrized s follows 1For nonflooded evportor opertion, the mixture hs lower evportor inlet temperture thn tht of R-22 But the temperture long the evportor circuit continues to rise even s pressure drops long the coil The temperture glide is only bout 3 F before dry-out occurs The verge mixture temperture is higher thn tht of R-22 For the flooded coil test, the temperture glide for the mixture is round 4 F over longer coil section 2 Temperture glide for the condenser het exchnger is not s cler s for the evportor het exchnger Over the sme coil section, R-22 shows 2 F drop becuse of the pressure drop The mixture, however, shows 6 F drop 3 The mount of het exchnged by the evportor with the mixture is not s high s with R-22, drop ofround 75% t 5 F mbient under nonflooded coil condition n flooded coil tests, the cooling cpcity increses for both R-22 nd the mixture: R-22 hs n increse of over 8%, while the mixture n increse of over 15% The cpcity difference between R-22nd the mixture under flooded evportor opertion is reduced (less thn 2%) 4 Refrigernt mss flow rte increses with mbient temperture Flooded coil opertion increses the m s flow rte for both R-22 nd the mixture R-22 hs 17% higher mss flow rte thn the mixturer t 5 F mbient nd under nonflooded evportor opertion For the flooded evportor test, the m s flow rte of R-22is still bout 10% higher thn tht of the mixture When the evportor is flooded, the mss flow rte of the mixture increses from 305 l b h to 370 lbh, nd tht of R-22increses from 364 bh to 412 lbh 5 R-22 requires more thn 3% higher compressor power consumption thn the mixture t 5 F mbient Flooded evportor opertion hs little effect on power consumption for R-22 for mbient temperture below 105 F For the mixture, flooded coil opertion increses the power consumption by bout 4% 6 The mixture hs higher compressor dischrge pressure thn R-22,nd the difference is broder t higher mbient tempertures At low mbient, 0 F or lower, the dischrge pressures for the mixture nd R-22 re lmost identicl Flooded coil opertion lowers the dischrge pressure for R-22 but increses it for the mixture 25

39 7 The mixture hs lower compressor dischrge temperture thn R-22 Flooded coil opertion lowers the dischrge temperture for both refrigernts by bout 20 F 8 The mixture hs higher compressor high-low pressure rtio thn does R-22 Flooded coil opertion reduces the rtio by 118% for the mixture nd by 13% for R-22 The test results revel tht the overll performnce of the mixture is close to tht of R-22, but it flls behind in het exchnger cooling cpcity nd results in higher compressor dischrge pressure One reson could be tht the components used in the test re ll designed for R-22 ppliction Modifiction of the components for the mixture opertion would improve the performnce; counter-cross-flow evportor nd condenser coils nd better expnsion device re exmples of needed chnges A counter-cross-flow evportor het exchnger would tke dvntge of the temperture glide nd probbly increse the temperture glide s well Flooded evportor coils hve positive efeect on both R-22 nd the mixture opertion The test results show tht flooded coil opertion ffects the mixture more thn R-22 Operting with flooded evportor coils, the mixture ctully performs better thn R-22 performs with nonflooded evportor coils, in terms of evportor cooling cpcity, refrigernt ms flow rte, nd compressor high-low pressure rtio 26

40 6 RECOMMENDATONS FOR FUTURE WORK c As the experiment ws going on, Du Pont developed new formul for the mixture we tested The originl composition of 30% R-32, 10% R-125, nd 60% R-134 hs been chnged to 23% R-32,25% R-125,nd 52% R-134 to reduce flmmbility of the mixture We recommend testing the updted ternry mixture refrigernt with concurrent-cross-flow nd counter-cross-flow evportor het exchngers (Kuo, 14) Becuse with flooded evportor opertion, even with concurrent-cross-flow evportor, the cooling cpcity of the mixture is only 2% below tht of R-22 t the sme operting conditions t would be interesting to test the mixture with counter-cross-flow evportor t flooded evportor condition t could possibly outperform R-22 under those conditions The recommended test will provide importnt informtion bout the performnce of this mixture using n off-the-shelf evportor het exchnger Proper modifiction of the het exchnger design to suit the mixture ppliction could be derived from the test results c c 27

41 7 REFERENCES Domnski, P A nd D A Didion 13, Thermodynmic Evlution of R-22 Alterntive Refrigernts nd Refrigernt Mixtures, ASHRAE Trns, Pt 2, pp Fischer, S K nd J R Snd 13, Screening Anlysis for Chlorine-Free Alterntive Refrigernts to Replce R-22 in Air Conditioning Applictions, ASHRAETrns, Pt 2, pp Kuo, W 14 Eflect of Countercurrent Crossflow Cooling Coil on System Performnce for Ozone-Sfe Refrigernt R-32/125/234 (30/10/6#~t%),MS thesis, Deprtment of Mechnicl Engineering, University of Florid, Ginesville, FL Mei, VC, nd E C Chen, 13, Liquid Over-Feedine Air Conditioning Svstem nd Method, USPtent , ssued on Sept 21, 13 Rdermcher, R nd D Jung 13, Theoreticl Anlysis of Replcement Refrigernts for R-22 for Residentil Uses, ASHME Trns, Pt 1, pp

42 NTERNALDSTRBUTON V D Bxter F C Chen J C Conklin D M Counce GE Courville V C Mei R WMurphy C C Rice 22 D E Riechle 23 R B Shelton 24 k Schffhuser P P Wolff ORNL Ptent Office Centrl Reserch Librry Document Reference Section Lbortory Records Lbortory Record - RC 33 D B Bivens, Engineering Fellow, Du Pont Chemicls, Fluorochemicls Lbortory, Chestnut Run Plz, PO Box 80711,Wilmington, DE D R Bohi, Director, Energy nd Nturl Resources Division, Resources for the Future, 1616 P Street, NW,Wshington, DC J Crlstedt, Korsbrsvgen 4C/447, Stockholm, Sweden 37 T E Drbeck, Professor, Deprtment of Sociology, University of Denver, Denver, co ~ E Grnryd, Deprtment of Thermodynmics nd Refrigertion, The Royl nstitute of Technology, Stockholm, Sweden 3 Esher Kweller, USDeprtment of Energy, Office of Building Technology, lo00 ndependence Ave Wshington, DC E-P HungFu, US Deprtment of Energy, Office of ndustril Technologies, Wshington DC R 0Hultgren, Energy Reserch nd Development, Deprtment of Energy, Ok Ridge Ntionl Lbortory, P 0 Box 2008,Ok Ridge, TN C D McCrcken, President, Clmc Mnufcturing Corportion, 101 West Sheffield Avenue, P 0 Box 710,Englewood, NJ Jmes Nelson, Refrigertion Reserch, nc 525 North Fifth Street, PO Box 86, Brighton, M W Noel, US Deprtment of Energy, Office of Building Technology, lo00 ndependence Ave Wshington, DC D O Nel, Deprtment of Mechnicl Engineering, Texs A & M University, College Sttion, TX 77843

43 46 MPte, Deprtment of Mechnicl Engineering, ow Stte University, A J Ryn, US Deprtment of Energy, Office of Building Technology, loo0 ndependence Ave Wshington, DC GSShely, Du Pont Chemicls, Huorochemicls Lbortory, Chestnut Run Plz, PO Box 80711,Wilmington, DE J BShrgo, Director, Office of Technology Trnsfer, 405 Kirklnd Hll, Vnderbilt University, Nshville, TN G E Sowers, P E, Senior Vice President, Lw Compnies Group, inc, 114 Townprk Drive, Suite 250,Kennesw, GA CMWlton, Ernest H Cockrell Centennil Chir in Engineering nd Chirmn, Deprtment of Civil Engineering, University of Texs t Austin, Austin, TX Office of Scientific nd Technicl nformtion, US Deprtment of Energy, POBox 62, Ok Ridge, TN 37831