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1、RefrigerationSystemPerformanceusingLiquid-SuctionHeatExchangersAbstractHeattransferdevicesareprovidedinmanyrefrigerationsystemstoexchangeenergybetWeenthecoolgaseousrefrigerantleavingtheevaporatorandWarmliquidrefrigerantexitingthecondenser.Theseliquid-suctionorsuction-lineheatexchangersc
2、an,insomecases,yieldimprovedsystemperformanceWhileinothercasestheydegradesystemperformance.Althoughpreviousresearchershaveinvestigatedperformanceofliquid-suctionheatexchangers,thisstudycanbedistinguishedfromthepreviousstudiesinthreeWays.First,thispaperidentifiesaneWdimensionlessgrouptoc
3、orrelateperformanceimpactsattributabletoliquid-suctionheatexchangers.Second,thepaperextendspreviousanalysestoincludeneWrefrigerants.Third,theanalysisincludestheimpactofpressuredropsthroughtheliquid-suctionheatexchangeronsystemperformance.ItisshoWnthatrelianceonsimplifiedanalysistechniqu
4、escanleadtoinaccurateconclusionsregardingtheimpactofliquid-suctionheatexchangersonrefrigerationsystemperformance.Fromdetailedanalyses,itcanbeconcludedthatliquid-suctionheatexchangersthathaveaminimalpressurelossontheloWpressuresideareusefulforsystemsusingR507A,R134a,R12,R404A,R290,R407C,
5、R600,andR410A.Theliquid-suctionheatexchangerisdetrimentaltosystemperformanceinsystemsusingR22,R32,andR717.IntroductionLiquid-suctionheatexchangersarecommonlyinstalledinrefrigerationsystemsWiththeintentofensuringpropersystemoperationandincreasingsystemperformance.Specifically,ASHRAE(1998
6、)statesthatliquid-suctionheatexchangersareeffectivein:1)increasingthesystemperformance2)subcoolingliquidrefrigeranttopreventflashgasformationatinletstoexpansiondevices3)fullyevaporatinganyresidualliquidthatmayremainintheliquid-suctionpriortoreachingthecompressor(s)6Figure1illustratesasi
7、mpledirect-expansionvaporcompressionrefrigerationsystemutilizingaliquid-suctionheatexchanger.Inthisconfiguration,hightemperatureliquidleavingtheheatrejectiondevice(anevaporativecondenserinthiscase)issubcooledpriortobeingthrottledtotheevaporatorpressurebyanexpansiondevicesuchasa