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1、IntroductionofThermalGGT/RE–EnvironmentTestTeamPrimaryMechanicofHeatTransferThermalenergytransport:causebytemperaturedifference,highT->lowTConductionHeattransferringbysolidmediumConvectionTransferringenergybetweensolidsurfaceandfluidMasstransportNatural(free)convectionForcedconvec
2、tionRadiationHeattransferringbyelectromagneticwavesConductionFourier’sLawQ=-KAΔT/ΔLQ:heattransferrateA:cross-sectionalareaofheatfluxΔT/ΔL:temperaturegradientK:thermalconductivity(W/mk)Ex.Al=230Cu=380Mylar=1.8ConvectionNewtoniancoolingLawQc=hcAs(Ts–Ta)Qc:convectionheattransferrateA
3、s:surfaceareaTs:surfacetemperatureofsolidTa:tmperatureofambienthc:heattransfercoefficient,f(flowtype,bodygeometry,physicalproperty,temperature,velocity,viscosity…)Naturalconvection&Forcedconvctionhcofair,naturalconvection:0.0015~0.015W/in2℃forcedconvection:0.015~0.15W/in2℃Radiatio
4、nQa=εσAF1-2(Ts4–Ta4)Qa:radiationheattransferrateε:emissivity,0≦ε≦1σ:Stefan-BoltzmannconstantA:surfaceareaF1-2:viewfactorTs:temperatureofbodysTa:temperatureofbodyaThermalResistanceR=V/IV:voltage=ΔT:temperaturedifferenceI:current=Q:heatConductionRk=ΔL/KAkConvectionRs=1/hcAsRadiation
5、Ra=(Ts–Ta)/εσAF1-2(Ts4–Ta4)BasicConceptsforNBThermalDesignThermalDesignTargetThermaldesignmustmeetthermalspec.ofCPU,allkeycomponents(HDD,FDD,CD-ROM,PCMCIA…),andallICchips(Chipset,VGA,RAM,PCMCIA…),andallICchips(Chipset,VGA,RAM,Audio…)ineachuserconditionsThermalResistanceΘj-a=(Tj–Ta
6、)/PcpuΘj-a:CPUjunctiontoambientthermalresistanceTj:CPUjunctiontemperatureTa:ambienttemperaturePcpu:CPUpowerBasicConceptsforNBThermalDesignSystemThermalCouplingeffectΘj-a=(Tj–Ta–Tsys)/PcpuTsys:systemtemperature=Psys*Θ=ΣPi*θi,(i:DRAM,Chipset,HDD,FDD,CD-ROM…)R:thermalcouplingfactorbe
7、tweenPcpuandPsysTj:CPUspec.forIntel:100℃Ta:OEMspec.,35℃Θj-a,Tsys:OEMdesigndependent,Tsys=10~15℃BasicConceptsforNBThermalDesignThermalSolutionsPassivethermalsolutionActivethermalsolutionHybridthermalsolutionRHERemoteHeatExchangerBasicConceptsforNBThermalDesignCharacteristicofagoodp
8、assivecomponentsSpreaderplateconn
