蒸汽喷射器喷射系数计算的热力学模型

徐海涛　桑芝富(,210009)　　,,、.IAPWS-IF97,、.,,;1,.,,.　　　　　TH451　TK212　　　　　　A　0438-1157(2004)05-0704-07THERMODYNAMICMODELSFORCALCULATINGENTRAINMENTRATIOOFSTEAM-JETEJECTORXUHaitaoandSANGZhifu(SchoolofMechanicalandPowerEngineering,NanjingUniversityofTechnology,Nanjing210009,Jiangsu,China)Abstract　Inthepresentwork,theprocessofsteam-jetejectorwasanalyzedindetail.Threethermodynamicmodelsforcalculatingentrainmentratioofsteam-jetejector:theidealmodel,themomentumconservationmodelandthekineticenergyconservationmodelwerededucedaccordingtothechangeinthermodynamicstate.TheIAPWS-IF97formulationwasusedtocomputesteamproperties,andtheeffectsofnozzle,mixinganddiffuserefficiencyonejectorperformancewerestudied.AlthoughtherewassomedifferencebetweentheMCmodelandtheidealmodelwhennoimperfectfactorswereconsidered,however,itwasfoundthattheMCmodelrepresentstheempiricalcurvesbetterthantheKECmodelifreasonableefficiencieswereused.Keywords　steam-jetejector,thermodynamicmodel,entrainmentratio,exergyefficiency　　2002-12-17,2003-03-06.:.:,,26,.　　,、,[1～5]、[6～10]、(verticalorshorttakeoffandlanding,V/STOL)[11～13],[14～18].1.,　　Receiveddate:2002-12-17.Correspondingauthor:Prof.SANGZhifu.E-mail:[e-mail]　,,.,、、.　　　　　　　55　5　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Vol.55　№5　20045　　Journal　of　Chemical　Industry　and　Engineering　(China)　　May　2004Fig.1　Schematicdiagramofsteam-jetejector　　　,∑F=∮Adp=Gp(1+u)v3-Gpvp2-GHvH2(1)KeenanNeumann[11,19],Elrod[20]Fab-ri[21],.(A=constant),(dp=0).,,,,,,,,,、,.、[22～24],.,,;,20℃,;,.,,.1　2,P-P2(H-H2)-3-C,.PH,hP、hH,pP、pH.,pPpHp2,P2H2.,.,p3,3.,,,,C.Fig.2　Enthalpy-entropydiagramrepresentationofsteam-jetejectorprocesses　,,,,u=GH/GP(2)u,hC=hP+uhH1+u(3)·705·　555　　　　　　　　　:u′,h′C=hP+u′hH1+u′(4),,s′C=sP+u′sH1+u′(5),h=hC.,sCs′C,pCp′C.,.2　,:(1),,;(2)();(3);(4)、(、、);(5);(6)1-3(momentumconservationmodel,MCmodel)(kineticenergyconservationmodel,KECmodel).3.2.1　,hP-h1′=12v21(6)v1=2(hP-h1′)(7),φn,Fig.3　Simplifiedenthalpy-entropydiagramrepresentationofsteam-jetejectorprocesses　v1=φn2(hP-h1′)(8)φn,φn=hP-h1hP-h1′(9)2.2　(MCmodel),φmGPv1=(GP+GH)v3(10)φmv1=(1+u)v3(11)(KECmodel),12GP(φmv1)2=12(GP+GH)v23(12)φ2mv21=(1+u)v23(13)2.3　hC″-h3=12v23(14)v3=2(hC″-h3)(15)v3=2(hC″-h3)φd(16)φd,φd=hC″-h3hC-h3(17)2.4　GPhP+GHhH=(GP+GH)hC(18)·706·　　　　　　　　　　　　　　　　　　　　　　　20045　u=hP-hChC-hH(19)(11)(19)φnφmφdhP-h1′hC″-h3=hP-hHhC-hH(20)ηnηmηdhP-h1′hC″-h3=hP-hHhC-hH2(21)(13)(19)φ2nφ2mφ2dhP-h1′hC″-h3=hP-hHhC-hH(22)ηnηmηdhP-h1′hC″-h3=hP-hHhC-hH(23)(21)(23)(MCmodel)(KECmodel).3　2,.(TheInternationalAssociationforthePropertiesofWaterandSteam,IAPWS)“IAPWS1997”,IAPWS-IF97[25].Fig.4　RegionsandequationsofIAPWS-IF97IF975,1,2,3,5g=g(p,T)f=f(ρ,T),(v、hs),4,4.IF9712T(p,h)T(p,s),hs,,.(MCmodel)(KECmodel),h3,(21)(23),10-3.,PH,.4　u,,(),.,,.,η=u(eC-eH)eP-eC(24)5.,1,.5(a),(MCmodel)(idealmodel),,;5(b),,,.(KECmodel),,.6(pP=1.101325MPa,TP=460K,pH=0.009MPa,TH=342K).[24].,(MCmodel)(ηn=0.7,ηm=1.0,ηd=0.9ηn=0.9,ηm=0.8,ηd=0.8),.7,:pP=1.101325MPa,TP=460K,pH=0.009MPa,·707·　555　　　　　　　　　:(a)compressionratioversusentrainmentratio　(b)exergyefficiencyversusentrainmentratioFig.5　Comparisonsofideal,KECandMCmodel(ηn=1.0,ηm=1.0,ηd=1.0)　Fig.6　Comparisonsoftheoreticalmodelsandempiricaldata(pP=1.101325MPa,TP=460K,pH=0.009MPa,TH=342K)　TH=342K,u=1,ηn=0.85,ηm=0.75,ηd=0.7.,,.,、,,.Fig.7　Contoursofexergyefficiencyasfunctionofnozzle,mixinganddiffuserefficiency　,KC(pC/pH)KE(pP/pH).8(),:pP=1.101325MPa,TP=460K,pH=0.009MPa,TH=342K,ηn=0.7,ηm=1.0,ηd=0.9.,,,;,;,.,,2～5(0.21.2).Fig.8　Entrainmentratioasfunctionofexpansionratioandcompressionratio·708·　　　　　　　　　　　　　　　　　　　　　　　20045　5　　,,,(MCmod-el)(KECmodel).,,;1,.,,.,,,,、、.,,.,.　　　　A———,m2F———,NG———,kg·s-1h———,kJ·kg-1KC———KE———p———,Pas———,kJ·kg-1·K-1u———v———,m·s-1η———ηd———ηm———ηn———φd———φm———φn———C———H———H2———　P———P2———1———2———3———References1　PowerRB.HowtoSpecify,EvaluateandOperateSteam-JetAirEjectors,Part1:Specification.HydrocarbonProcessingandPetroleumRefiner,1964,43(2):121—1262　PowerRB.HowtoSpecify,EvaluateandOperateSteam-jetAirEjectors,Part2:Evaluation.HydrocarbonProcessingandPetroleumRefiner,1964,43(3):138—1423　PowerRB.HowtoSpecify,EvaluateandOperateSteam-jetAirEjectors,Part3:Operation.HydrocarbonProcessingandPetroleumRefiner,1964,43(4):149—1524　AlyNH,KarameldinA,ShamloulMM.ModelingandSimulationofSteamJetEjectors.Desalination,1999,12:1—85　GuptaSK,SinghRP,DixitRS.AComparativeParametricStudyofTwoTheoreticalModelofaSingle-stage,Single-fluid,SteamJetEjector.TheChemicalEngineeringJournal,1979,18:81—856　GrazziniG,MariniA.ASimpleProgramtoDesignaMulti-stageJet-pumpforRefrigerationCycles.EnergyConversationandManagement,1998,39:1827—18347　HuangBJ,ChangJM,WangCP,PetrenkoVA.A1-DAnalysisofEjectorPerformance.InternationalJournalofRefrigeration,1999,22:354—3648　LearWE,SherifSA,SteadhamJM.DesignConsiderationofJetPumpswithSupersonicTwo-phaseFlowandShocksforRefrigerationandThermalManagementApplications.InternationalJournalofEnergyResearch,2000,24:1373—13899　SunDW.ComparativeStudyofthePerformanceofanEjectorRefrigerationCycleOperatingwithVariousRefrigerants.EnergyConversionandManagement,1999,40:873—88410