ASHRAE.4411-2001 Modeling and Analysis of Gas Coolers

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1、4411ModelingandAnalysisofGasCoolersXiandeFang,Ph.D.ClarkW.Bullard,Ph.D.PredragS.Hrnjak,Ph.D.MemberASHRAEMemberASHRAEABSTRACTchangingsothattheheatexchangeriscalledagascoolerinsteadofacondenser.Themathematicalmodelofgascoolersisthecornerstoneofgascoolerdesignandsystemmodelingofth

2、eCOtran-Althoughnophasechangetakesplaceatsupercritical2scriticalcycle.Modelingisapowerfulmeanstoanalyzethepressures,thethermophysicalpropertiesofCO2changedras-thermalperformancesofgascoolers.Thispaperproposesatically(SpanandWagner1996;Vargaftik1975;Vesovicetal.mathematicalmodel

3、ofgascoolersforcalculatingheattrans-1990)duringtheprocess.Inthesecircumstances,theheatferandpressuredropatsupercriticalpressuresinbothtran-transfercoefficientandpressuredroparegreatlydependentonsitionalandfullydevelopedturbulentregimes.Basedontheboththelocalmeantemperatureandth

4、eheatflux,wherethemathematicalmodel,acomputersimulationprograminEESconventionalmodelscouldnotapply(Pitlaetal.1998;Fangforgascoolersisdeveloped.Verificationwithexperimental1999).dataismadethereafter.Themodelpredictionsdescribe97%Fang(1999)offersacomprehensivesurveyofsingle-ofthe

5、experimentaldataofthecapacitywithin±5%and97%phasein-tubeheattransfercorrelations,CO2supercriticalheatoftheexperimentaldataoftherefrigeranttemperaturesatthetransfer,frictionfactorcorrelations,thecalculationofpres-gascooleroutletwithdeviationwithin±1°C.suredropinthesupercriticalc

6、onditions,andheattransferandfrictionfactorcorrelationsonthegascoolerair-side.HehasINTRODUCTIONalsodevelopedaCO2-specificheattransferequation.CarbondioxideisconsideredasapotentialalternativeSeveralpapersrelatedtogascoolermodelinghavebeenrefrigerantforautomotiveair-conditioningan

7、dheatpumppublished(SchonfeldandKraus1997;RiebererandHalozansystems.ThecapacityandCOPofCO2systemsdependonthe1997;RobinsonandGroll1998;Fang1999).UsingGnielin-pressureinthehighsidebecausetheyoperateinatranscriticalski’s(1976)equations,SchonfeldandKraus(1997)andcycleundermostcondit

8、ions.TheprocesspathofaCO2transcriticalcycle,asshowninF