IntroductionofThermalGGT/RE-EnvironmentTestTeam|PrimaryMechanicofHeatTransfer余_Thermalenergytransport:伟仪causebytemperaturedifference,highT-lowTConductionHeattransferringbysolidmediumConvectionTransferringenergybetweensolidsurfaceandfluidMasstransportNatural(free)convectionForcedconvectionRadiationHeattransferringbyelectromagneticwaves3Conduction伟FouriersLaWQ=-KAAT/ALQ:heattransferrateA:cross-sectionalareaofheatfluxATAyALitemperature-gradientK:thermalconductivity(W/mJEX.Al=230CUu=380Mylar=1.8Convection伟NewtoniancoolingLawQc=hcAs(Ts-Ta)Qc:convectionheattransferrateAs:surfaceareaTs:surfacetemperatureofsolidTa:tmperatureofambienthc;heattransfercoefficient,f(flowtype,bodygeometry,physicalproperty,temperature,velocity,Viscosity.)企Naturalconvection&Forcedconvctionhcofairnaturalconvection:0.0015“.0.015W/in2Cforcedconvection:0.0150.15W/inzC_RadiationQa=soAFl.(Ts4-Ta4)Qa:radiationheattransferrate8:emissivity,0不s与1c:Stefan-BoltzmannconstantA:stffaceareaFl,:viewfactorTs:temperatureofbodysTa:temperatureofbodya3ThermalResistance伟R=V/IV:voltage=AT:temperaturedifferenceI:current=Q:heat伟ConductionRk=QAUKARR伟ConvectionRs=11huAs伟RadiationRa=(Ts-Ta)/gGAFlo(Ts4-Ta4)BasicConceptsforNBThermalDesign企ThermalDesignTargetThermaldesignmustmeetthermalspec,ofCPU,allkeycomponents(HDD,FDD,CD-ROM,PCMCIA.),andallICchips(Chipset,VGA,RAM,PCMCIA.),andallICchips(Chipset,VGA,RAM,Audio.)ineachuserconditions企TherimalResistariCeis=(j-Ta)/Pcpuja:CPUjunctiontoambientthermalresistance人:CPUjunctiontemperatureTa:ambienttemperaturePcpu:CPUpowerBasicConceptsforNBThermalDesign伟SystemThermalCouplingeffectja=(Tj-Ta-Tsys)/PcpuTsys:systemtemperature=Psys*=ZPikb,(i:DRAM,Chipset,HDD,FDD,CD-ROM.)RithermatcouplingfectorbetwesnPcpuandPsys人:CPUspec.forIntel:100CTa:OEMspec.,35C98ja,Tsys:OEMdesigndependent,Tsys=1015CBasicConceptsforNBThermalDesign伟ThermalSolutionsPassivethermalsolution“Activethermalsolution“Hybiidithefmalsblation伟RHERemoteHeatExchangerBasicConceptsforNBThermalDesign仁Characteristicofagoodpassivecomponents“SpreaderplateconnectedtoCPUshouldbeaslargea5possibleTemperaturevariationonspreaderplateshouldbeminimal企Characteristicofagood9activecomponent“AifinletandoutletshouldbecleariydefinedLengthofairpassagethroughNBshouldbesmalltokeeppressuredroplow,flowratehigh“Possiblereducenoiselevelofthefan“DesignmustbecapableofventingaportionofhotairfromNBinside