A Design Approach to Thermal Characterization of Forced Convection Systems Using Superposition in CFD
A set of computational analyses was performed for a system level model to test the validity of the concept of the adiabatic heat transfer coefficient (AHTC) and superposition kernel function (SKF) using Flotherm, a commercial CFD tool. The AHTC is a special sub-set of the general definition of the heat transfer coefficient and is in fact the correct heat transfer coefficient for the immediate ambient temperature that a surface will see. This makes the AHTC compatible with the principle of superposition and therefore a useful tool in the design process. Because CFD solves the physics of flow and heat transfer implicitly for a model, the concept of the AHTC can be used directly without additional analysis methods except for a quick matrix multiplication process. The method in CFD requires that each heat source is activated as a unit value in turn and the results are stored for any number of probed points in the system. These points are then tabulated and post-processed with the actual system heat load to determine the system temperatures. For forced convection systems where radiation and natural convection effects are minimal, the results of this study have shown excellent correlation.
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