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1、RefrigerationSystemPerformanceusingLiquid-SuctionHeatExchangersS.A.Klein,D.T.Reindl,andK.BroWnellCollegeofEngineeringUniversityofWisconsin-MadisonAbstractHeattransferdevicesareprovidedinmanyrefrigerationsystemstoexchangeenergybetWeenthecoolgaseousrefrigerantleavingtheevapor
2、atorandWarmliquidrefrigerantexitingthecondenser.Theseliquid-suctionorsuction-lineheatexchangerscan,insomecases,yieldimprovedsystemperformanceWhileinothercasestheydegradesystemperformance.Althoughpreviousresearchershaveinvestigatedperformanceofliquid-suctionheatexchangers,th
3、isstudycanbedistinguishedfromthepreviousstudiesinthreeWays.First,thispaperidentifiesaneWdimensionlessgrouptocorrelateperformanceimpactsattributabletoliquid-suctionheatexchangers.Second,thepaperextendspreviousanalysestoincludeneWrefrigerants.Third,theanalysisincludestheimpac
4、tofpressuredropsthroughtheliquid-suctionheatexchangeronsystemperformance.ItisshoWnthatrelianceonsimplifiedanalysistechniquescanleadtoinaccurateconclusionsregardingtheimpactofliquid-suctionheatexchangersonrefrigerationsystemperformance.Fromdetailedanalyses,itcanbeconcludedth
5、atliquid-suctionheatexchangersthathaveaminimalpressurelossontheloWpressuresideareusefulforsystemsusingR507A,R134a,R12,R404A,R290,R407C,R600,andR410A.Theliquid-suctionheatexchangerisdetrimentaltosystemperformanceinsystemsusingR22,R32,andR717.IntroductionLiquid-suctionheatexc
6、hangersarecommonlyinstalledinrefrigerationsystemsWiththeintentofensuringpropersystemoperationandincreasingsystemperformance.Specifically,ASHRAE(1998)statesthatliquid-suctionheatexchangersareeffectivein:1)increasingthesystemperformance2)subcoolingliquidrefrigeranttopreventfl
7、ashgasformationatinletstoexpansiondevices3)fullyevaporatinganyresidualliquidthatmayremainintheliquid-suctionpriortoreachingthecompressor(s)Figure1illustratesasimpledirect-expansionvaporcompressionrefrigerationsystemutilizingaliquid-suctionheatexchanger.Inthisconfiguration,h
8、ightemperatureliquidleavingtheheatrejectiondevice(anevaporativecondenserinthiscase