[电子设备热设计]Icepak Basic Training.ppt

Heat Exchanger Two loop heat exchanger parallel flow or counter flow single or multiple passes Inner and outer loops Can be the same or different fluids inner loop is typically the air inside Icepak cabinet Motivation Impractical to model both loops in detail for a system model too costly computationally Employ compact modeling approach Simulation of heat exchanger without modeling both loops 3d converted to a 2d representation significant cell count savings Equivalent pressure drop through heat exchanger loss coefficient(s) Equivalent energy exchange between loops user specified heat transfer coefficient Requires data from either detailed Icepak model of both loops empirical measurements vendor Pressure Drop Constant loss coefficient user specifies kLbased on empirical, computational or vendor data Polynomial loss coefficient can be specified as a function of velocity user specifies rn, which are polynomial coefficients Heat Transfer Fixed heat flux if the total heat exchange between loops is known Heat transfer coefficient constant user specifies h polynomial as a function of velocity user specifies hn external temperature is inlet for external loop Components of the package forming critical heat conduction pathway are modeled Such components are simplified by lumping repetitive objects and assigning them effective properties Exploits the power of thin conducting plates in modeling very thin, highly conducting layers Choice of three meshers available: Two Hexahedral meshers Suited for most (99%) of electronics cooling applications. Unstructured It can be used for most applications satisfactorily Cartesian Tetrahedral mesher Intended for some complex geometry Must be used for ellipsoids, elliptical cylinders, or polygonal ducting All the methods are fully automated Can generate computational meshes at varying levels of complexity No parameters set Parameters defined on an object by object basis After meshing, Icepak loads the mesh and checks th