热虹吸管研究进展

Ageneralizedmodelingmethodologyfortwo-phasethermosyphonloopheatexchanger(undersmalltemperaturedifference?)Contents2IntroductionModellingmethodologyResultsanddiscussion3.1Experimentalverification3.2Internalparameterdistribution3.3Effectofrefrigerantcharge3.4Effectoftemperaturedifference3.5Effectofverticaldistance3.6EffectofflowresistantConclusionIntroduction-workingprincipleWidelyusedinindustrialapplicationduetosimplicity,highefficiency,energysavingConsistsofevaporator,condenser,riseranderTheloopthermodynamicstateisdeterminedbyonepointpressure,enthalpy,flowrateSimulationisnecessarytodevelopperformanceandreliabilityIntroduction-existingmodels[1]GarrityPT,KlausnerJF,MeiR.Aflowboilingmicrochannelevaporatorplateforfuelcellthermalmanagement.HeatTransferEngineering.2007;28:877-84.[2]RaoN,SekharCC,MaitiB,DasP.Steady-stateperformanceofatwo-phasenaturalcirculationloop.Internationalcommunicationsinheatandmasstransfer.2006;33:1042-52.[3]KhodabandehR.Pressuredropinriserandevaporatorinanadvancedtwo-phasethermosyphonloop.InternationalJournalofRefrigeration.2005;28:725-34.[4]KhodabandehR.Heattransferintheevaporatorofanadvancedtwo-phasethermosyphonloop.InternationalJournalofRefrigeration.2005;28:190-202.[5]ImuraH,SaitoY,KatsumataY.FlowandHeatTransferCharacteristicsinaTwo-PhaseLoopThermosyphon.TransactionsoftheJapanSocietyofRefrigeratingandAirConditioningEngineers.1988;5:63-72.[6]DubeV,AkbarzadehA,AndrewsJ.Theeffectsofnon-condensablegasesontheperformanceofloopthermosyphonheatexchangers.Appliedthermalengineering.2004;24:2439-51.Mostmodelsaredevelopedunderlargetemperaturedifferenceandheatflux,forelectronicscoolingorwaterreactor,etc.Themodelsarespecificandplete,onlyapplicabletospecificexperimentalsetup,cannotdeterminetheloopthermodynamicstateaccordingtoexternalthermalconditionIntroduction-innovativepointsAgeneralizedmodel(withoutinternalknownparameters)Threeunknowninternalparameters(onepointpressure,temperature,massflowrate)Threeconservationlawsused(momentum,energy,mass)Notalwayshydraulicfillinginer(undersmalltemperaturedifference)IgnorethephenomenonunderlargetemperaturedifferenceCloselyrelatedwithmassflowrateAssumegascolumnintheupperSuitableforHVACsystem\heatrecoverySmalltemperaturedifferenceSmallheatfluxCapabletosimulatetheeffectofchargeContents6IntroductionModellingmethodologyResultsanddiscussion3.1Experimentalverification3.2Internalparameterdistribution3.3Effectofrefrigerantcharge3.4Effectoftemperaturedifference3.5Effectofverticaldistance3.6EffectofflowresistantConclusionModelingmethodologyMomentummodels

Heattransfermodelsinevaporator

HeattransfermodelsincondenserModeling-fullhydraulicfilling(Tsc>0)MomentumconservationMassvelocityGEnergyconservationSubcoolingTscMassconservationPressureP0MomentumconservationMassvelocityGEnergyconservationLiquidcolumnheightH0MassconservationPressureP0Modeling-partialhydraulicfilling(Tsc=0)Contents10IntroductionModellingmethodologyResultsanddiscussion3.1Experimentalverification3.2Internalparameterdistribution3.3Effectofrefrigerantcharge3.4Effectoftemperaturedifference3.5Effectofverticaldistance3.6EffectofflowresistantConclusion3.1Experimentalverification(simple)实验验证ItemsCondenserEvaporatorTubebundlespecification3rows,28tubesperrow3rows,28tubesperrowTubelength=700mmTubelength=700mmTubepitch=25.4mm,rowpitch=22.2mmTubesizeOuterdiameter=9.52mm;Innerdiameter=0.7mmFinspecificationWavyfin;Pitch=1.814mm;Thickness=0.105mmHeightdifference2m3.2Internalparameterdistribution内部参数分布M=5kgTein=10℃Tcin=30℃压力与压降分布干度和含气率制冷剂质量分布温度分布传热系数分布焓值分布3.3Refrigerantcharge制冷剂充注量影响Δt=20℃M=8kgHeattransferrate传热量Massflowvelocity质量流速Pressureatcondenseroutlet冷凝器出口压力Subcoolingatcondenseroutlet冷凝器出口过冷度Vaporqualityatevaporatoroutlet蒸发器出口干度Liquidcolumnheightiner下降管液柱高度3.4Temperaturedifference温差影响CondenseroutletsubcoolingLiquidcolumnheightLargertemperaturedifference,,Higherliquidcolumn,Largersubcoolingdegreetendstohydraulicfilling温差越大，液柱高度越大，过冷度越大，即下降管越容易满液Differentrefrigerantcharge,differentcriticalpoint,largerrefrigerantcharge,thecriticalpointappearsatlesstemperaturedifference充注量越大，不满液出现在越小的温差下，即下降管越容易满液3.4Temperaturedifference温差影响HeattransferrateMassflowvelocityTheheattransferrateriseslinearly,thenrisesrelativelyslowlywiththetemperaturedifferenceincreases传热量随着温差先线性增加，后增速降低，且存在一定启动温差，与实验趋势相符Forlargerrefrigerantcharge,themassflowvelocityfirstincreasesandthendecreases,forlessrefrigerantcharge,themassflowvelocityincreases随着温差增大，大充注量时，质量流速先增大后减小，小充注量时，质量流速一直增大3.4Temperaturedifference温差影响CondenseroutletpressureVaporqualityatevaporatoroutletPressurerisesasthetemperaturedifferenceincreasesThevaporqualityrisesasthetemperaturedifferenceincreases小充注量小温差（非满液）下个别点表现出不同的趋势，可能是因为此时，随着温差增大，质量流量增速比传热量增速达引起的3.5-Verticaldistance高差影响HeattransferrateMassflowvelocity3.5-Verticaldistance高差影响PressureatcondenseroutletSubcoolingatcondenseroutletLiquidcolumnheightinerVaporqualityatevaporatoroutlet3.6-Flowresistance阻力影响HeattransferrateMassflowvelocity3.6-Flowresistance阻力影响PressureatcondenseroutletSubcoolingatcondenseroutletLiquidcolumnheightinerVaporqualityatevaporatoroutletContents21IntroductionModellingmethodologyResultsanddiscussion3.1Experimentalverification3.2Internalparameterdistribution3.3Effectofrefrigerantcharge3.4Effectoftemperaturedifference3.5Effectofverticaldistance3.6EffectofflowresistantConclusionConclusionProposeageneralizedmodelingmethodologytwo-phasethermos