暖通空调专业毕业设计外文翻译1.docx

暖通空调专业毕业设计外文翻译1.docx

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暖通空调专业毕业设计外文翻译1

RefrigerationSystemPerformanceusingLiquid-SuctionHeatExchangers

S.A.Klein,D.T.Reindl,andK.BroWnell

CollegeofEngineering

UniversityofWisconsin-Madison

Abstract

HeattransferdevicesareprovidedinmanyrefrigerationsystemstoexchangeenergybetWeenthecoolgaseousrefrigerantleavingtheevaporatorandWarmliquidrefrigerantexitingthecondenser.Theseliquid-suctionorsuction-lineheatexchangerscan,insomecases,yieldimprovedsystemperformanceWhileinothercasestheydegradesystemperformance.Althoughpreviousresearchershaveinvestigatedperformanceofliquid-suctionheatexchangers,thisstudycanbedistinguishedfromthepreviousstudiesinthreeWays.First,thispaperidentifiesaneWdimensionlessgrouptocorrelateperformanceimpactsattributabletoliquid-suctionheatexchangers.Second,thepaperextendspreviousanalysestoincludeneWrefrigerants.Third,theanalysisincludestheimpactofpressuredropsthroughtheliquid-suctionheatexchangeronsystemperformance.ItisshoWnthatrelianceonsimplifiedanalysistechniquescanleadtoinaccurateconclusionsregardingtheimpactofliquid-suctionheatexchangersonrefrigerationsystemperformance.Fromdetailedanalyses,itcanbeconcludedthatliquid-suctionheatexchangersthathaveaminimalpressurelossontheloWpressuresideareusefulforsystemsusingR507A,R134a,R12,R404A,R290,R407C,R600,andR410A.Theliquid-suctionheatexchangerisdetrimentaltosystemperformanceinsystemsusingR22,R32,andR717.

Introduction

Liquid-suctionheatexchangersarecommonlyinstalledinrefrigerationsystemsWiththeintentofensuringpropersystemoperationandincreasingsystemperformance.Specifically,ASHRAE（1998）statesthatliquid-suctionheatexchangersareeffectivein:

1）increasingthesystemperformance

2）subcoolingliquidrefrigeranttopreventflashgasformationatinletstoexpansiondevices

3）fullyevaporatinganyresidualliquidthatmayremainintheliquid-suctionpriortoreachingthecompressor（s）

Figure1illustratesasimpledirect-expansionvaporcompressionrefrigerationsystemutilizingaliquid-suctionheatexchanger.Inthisconfiguration,hightemperatureliquidleavingtheheatrejectiondevice（anevaporativecondenserinthiscase）issubcooledpriortobeingthrottledtotheevaporatorpressurebyanexpansiondevicesuchasathermostaticexpansionvalve.ThesinkforsubcoolingtheliquidisloWtemperaturerefrigerantvaporleavingtheevaporator.Thus,theliquid-suctionheatexchangerisanindirectliquid-to-vaporheattransferdevice.Thevapor-sideoftheheatexchanger（betWeentheevaporatoroutletandthecompressorsuction）isoftenconfiguredtoserveasanaccumulatortherebyfurtherminimizingtheriskofliquidrefrigerantcarrying-overtothecompressorsuction.IncasesWheretheevaporatoralloWsliquidcarry-over,theaccumulatorportionoftheheatexchangerWilltrapand,overtime,vaporizetheliquidcarryoverbyabsorbingheatduringtheprocessofsubcoolinghigh-sideliquid.

Background

StoeckerandWalukas（1981）focusedontheinfluenceofliquid-suctionheatexchangersinbothsingletemperatureevaporatoranddualtemperatureevaporatorsystemsutilizingrefrigerantmixtures.Theiranalysisindicatedthatliquid-suctionheatexchangersyieldedgreaterperformanceimprovementsWhennonazeotropicmixturesWereusedcomparedWithsystemsutilizingsinglecomponentrefrigerantsorazeoptropicmixtures.McLinden（1990）usedtheprincipleofcorrespondingstatestoevaluatetheanticipatedeffectsofneWrefrigerants.HeshoWedthattheperformanceofasystemusingaliquid-suctionheatexchangerincreasesastheidealgasspecificheat（relatedtothemolecularcomplexityoftherefrigerant）increases.DomanskiandDidion（1993）evaluatedtheperformanceofninealternativestoR22includingtheimpactofliquid-suctionheatexchangers.Domanskietal.（1994）laterextendedtheanalysisbyevaluatingtheinfluenceofliquid-suctionheatexchangersinstalledinvaporcompressionrefrigerationsystemsconsidering29differentrefrigerantsinatheoreticalanalysis.Bivensetal.（1994）evaluatedaproposedmixturetosubstituteforR22inairconditionersandheatpumps.Theiranalysisindicateda6-7%improvementforthealternativerefrigerantsystemWhensystemmodificationsincludedaliquid-suctionheatexchangerandcounterfloWsystemheatexchangers（evaporatorandcondenser）.Bittleetal.（1995a）conductedanexperimentalevaluationofaliquid-suctionheatexchangerappliedinadomesticrefrigeratorusingR152a.TheauthorscomparedthesystemperformanceWiththatofatraditionalR12-basedsystem.Bittleetal.（1995b）alsocomparedtheASHRAEmethodforpredictingcapillarytubeperformance（includingtheeffectsofliquid-suctionheatexchangers）Withexperimentaldata.Predictedcapillarytube