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1、外文翻譯（外文翻譯（1）RefrigerationRefrigerationSystemSystemPerfmancePerfmanceusingusingLiquidSuctionLiquidSuctionHeatHeatExchangersExchangersS.A.KleinD.T.ReindlK.BroWnellCollegeofEngineeringUniversityofWisconsinMadisonAbstractHea
2、ttransferdevicesareprovidedinmanyrefrigerationsystemstoexchangeenergybetWeenthecoolgaseousrefrigerantleavingtheevapatWarmliquidrefrigerantexitingthecondenser.Theseliquidsuctionsuctionlineheatexchangerscaninsomecasesyield
3、improvedsystemperfmanceWhileinothercasestheydegradesystemperfmance.AlthoughpreviousresearchershaveinvestigatedperfmanceofliquidsuctionheatexchangersthisstudycanbedistinguishedfromthepreviousstudiesinthreeWays.Firstthispa
4、peridentifiesaneWdimensionlessgrouptocrelateperfmanceimpactsattributabletoliquidsuctionheatexchangers.SecondthepaperextendspreviousanalysestoincludeneWrefrigerants.Thirdtheanalysisincludestheimpactofpressuresthroughtheli
5、quidsuctionheatexchangeronsystemperfmance.ItisshoWnthatrelianceonsimplifiedanalysistechniquescanleadtoinaccurateconclusionsregardingtheimpactofliquidsuctionheatexchangersonrefrigerationsystemperfmance.Fromdetailedanalyse
6、sitcanbeconcludedthatliquidsuctionheatexchangersthathaveaminimalpressurelossontheloWpressuresideareusefulfsystemsusingR507AR134aR12R404AR290R407CR600R410A.Theliquidsuctionheatexchangerisdetrimentaltosystemperfmanceinsyst
7、emsusingR22R32R717.IntroductionLiquidsuctionheatexchangersarecommonlyinstalledinrefrigerationsystemsWiththeintentofensuringpropersystemoperationincreasingsystemperfmance.SpecificallyASHRAE(1998)statesthatliquidsuctionhea
8、texchangersareeffectivein:1)increasingthesystemperfmance2)subcoolingliquidrefrigeranttopreventflashgasfmationatinletstoexpansiondevices3)fullyevapatinganyresidualliquidthatmayremainintheliquidsuctionpritoreachingthecompr
9、ess(s)Figure1illustratesasimpledirectexpansionvapcompressionrefrigerationsystemutilizingaliquidsuctionheatexchanger.Inthisconfigurationhightemperatureliquidleavingtheheatrejectiondevice(anevapativecondenserinthiscase)iss
10、ubcooledpritobeingthrottledtotheevapatpressurebyanexpansiondevicesuchasathermostaticexpansionvalve.Thesinkfsubcooling浙江海洋學(xué)院畢業(yè)設(shè)計(jì)3R134aR407CR410AR12R22R32R717.Thispaperextendstheresultspresentedinpreviousstudiesinthatitcon
11、sidersneWrefrigerantsitspecificallyconsiderstheeffectsofthepressuresitpresentsgeneralrelationsfestimatingtheeffectofliquidsuctionheatexchangersfanyrefrigerant.HeatExchangerEffectivenessTheabilityofaliquidsuctionheatexcha
12、ngertotransferenergyfromtheWarmliquidtothecoolvapatsteadystateconditionsisdependentonthesizeconfigurationoftheheattransferdevice.Theliquidsuctionheatexchangerperfmanceexpressedintermsofaneffectivenessisaparameterintheana
13、lysis.Theeffectivenessoftheliquidsuctionheatexchangerisdefinedinequation(1):Wherethenumericsubedtemperature(T)valuescrespondtolocationsdepictedinFigure1.Theeffectivenessistheratiooftheactualtomaximumpossibleheattransferr
14、ates.Itisrelatedtothesurfaceareaoftheheatexchanger.AzerosurfacearearepresentsasystemWithoutaliquidsuctionheatexchangerWhereasasystemhavinganinfiniteheatexchangerareacrespondstoaneffectivenessofunity.Theliquidsuctionheate
15、xchangereffectstheperfmanceofarefrigerationsystembyinfluencingboththehighloWpressuresidesofasystem.Figure2shoWsthekeystatepointsfavapcompressioncycleutilizinganidealizedliquidsuctionheatexchangeronapressureenthalpydiagra
16、m.Theenthalpyoftherefrigerantleavingthecondenser(state3)isdecreasedpritoenteringtheexpansiondevice(state4)byrejectingenergytothevaprefrigerantleavingtheevapat(state1)pritoenteringthecompress(state2).Pressurelossesarenots
17、hoWn.Thecoolingofthecondensatethatoccursonthehighpressuresideservestoincreasetherefrigerationcapacityreducethelikelihoodofliquidrefrigerantflashingpritoreachingtheexpansiondevice.OntheloWpressuresidetheliquidsuctionheate
18、xchangerincreasesthetemperatureofthevapenteringthecompressreducestherefrigerantpressurebothofWhichincreasethespecificvolumeoftherefrigeranttherebydecreasethemassfloWratecapacity.Amajbenefitoftheliquidsuctionheatexchanger
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