传热学4-TransientHeatConduction-2010.ppt

文档介绍：Chapter4TransientHeatConductionsteadyheattransferunsteadyheattransfer14-1LumpedSystemAnalysis4-2TransientHeatConductioninLargePlaneWalls,LongCylinders,andSpheres4-3TransientHeatConductioninSemi-InfiniteSolids4-4TransientHeatConductioninMultidimensionalSystem4-5SummaryChapter4TransientHeatConductionContents2Chapter4TransientHeatConductionGeneralFormofHeatConductionEquation:emperaturefield:ime:3Chapter4TransientHeatConduction4-1LumpedSystemAnalysis(LumpedParameterAnalysisMethod)ConductionResistance0lumpedsystem4Integratingfromt=0,atwhichT=Ti,toanytimet,atwhichT=T(t),givesChapter4TransientHeatConduction4-1LumpedSystemAnalysisEnergyBalancewhereV,A,m5Chapter4TransientHeatConduction4-1LumpedSystemAnalysis-timeconstantofthesystem6Therateofheattransferbetweenthebody&itsenvironmentattimet:Chapter4TransientHeatConduction4-1LumpedSystemAnalysisTheamountofheattransfer(t=0~t)7CriteriaforLumpedSystemAnalysisChapter4TransientHeatConduction4-1LumpedSystemAnalysisFourierNumber(Fo)BiotNumber(Bi)dimensionless8CriteriaforLumpedSystemAnalysisChapter4TransientHeatConduction4-1LumpedSystemAnalysisCharacteristicLength:BiotNumber:Criteria:-1LumpedSystemAnalysisFourierNumber(Fo):Criteria:Shouldbelargeenough10