A Simple Thermal Model for Mixed Convection From Protruding Heat Sources

Abstract

This paper reports the results of numerical and experimental investigations of conjugate mixed convection from a vertical channel with sets of protruding heat sources. The goal of this study is to investigate the possibility of obtaining reasonably accurate results with a simpler or compact thermal model that replaces a set of protruding heat sources with a heat source of appropriate thickness that occupies the whole of the channel wall. Commercially available FLUENT 6.3 was used for the simulations. In order to validate the numerical results, a low-speed vertical wind tunnel has been employed. These are followed by three-dimensional simulations for various heat transfer coefficients on the back side of the printed circuit board (PCB). The differences between the computational fluid dynamics (CFD) predicted and experimentally measured temperatures were minimized using least squares and the optimum value of heat transfer coefficient was obtained for use in the simple model. The effect of Reynolds number on heat transfer has been analyzed for both the full CFD and simpler thermal models. The variation of error in the maximum temperature between the full CFD model and the simpler thermal model under different conditions, as the number of chips changes from three to eight, is studied.