Compact Heat Sink Simulations in both Forced and Natural Convection Flows

Abstract

In this article, the modeling of heat sinks is carried out using electronic cooling software under both forced and natural convection conditions. Simulations are applied to both detailed and compact heat sink models. The compact models are based on the volume resistance approach also known as the porous block model. These models are devised with the intention of approximating actual heat sink behavior while providing substantial savings in computational effort. In some cases, results obtained from numerical simulations are compared with independent laboratory measurements. This is accomplished with both forced and natural convection flow conditions. In the case of forced convection, the effective thermal conductivity of the compact heat sink is calculated directly from the Nusselt number correlation for flow over a flat plate. When this value is used, the numerically determined thermal resistance of the compact heat sink is found to compare well with the experimental value. In the case of natural convection, the effective thermal conductivity of the compact heat sink is calculated using the corresponding Nusselt number correlation for free convection over a vertical plate. The increased complexity of the correlation for free convection necessitates an iterative solution for the effective thermal conductivity. In this case also, it is shown that results obtained from CFD simulations compare favorably with available laboratory measurements. The case-studies illustrate the manner in which compact heat sinks can be conveniently used to reduce the needed computational cost, time and resources while producing sufficiently reliable results.