A numerical analysis of convective heat transfer in channels simulating electronic components

Abstract

The cooling performance of two dimensional channel flow simulating channels of electronic components has been studied numerically. A channel is formed with the substrates on which the heat sources are surface-mounted regularly in the stream - wise direction, and repeated identically in the transverse direction. The channel thus formed is coupled thermally with the neighboring channels via the substrates. Periodically fully developed flow (PDF) has been examined both for laminar and turbulent flow regimes. In addition, developing flow (DF) has been studied for laminar flow only to examine the entry effect. Both convection-only and conjugate conduction/convection modes of heat transfer are considered in the analysis. The control volume based finite difference method using SIMPLER algorithm is adapted for numerical calculations, incorporating a k-ε model. The results of DF and PDF are obtained independently and compared for flow and thermal fields in terms of module based temperatures. Calculations are made for a wide range of independent parameters such as Reynolds number (Re), conductivity ratio of the substrate to fluid (K[s]/ K[f]) and geometric factors. The results show that the assumption of constant temperature or heat flux is improper for block (heat source) or module surface. This is more pronounced for turbulent flow and blocks whose conductivities are low. The Nusselt number or overall thermal resistance (thermal performance) of a block in laminar PDF module is nearly independent of Re; however, there exists a minimum Re below which the thermal performance drastically deteriorates. This minimum Re exists between 100 and 500 depending on the geometric parameters. Thermal performance is enhanced with an increase in the substrate conductivity and continues up to a value of 10 for K[s]/K[f]. Any further increase of K[s]/ K[f] results in small or no improvement in the thermal performance because of the limitation of the cooling capacity of the channel. The same trend is found for laminar DF but generally higher performance is obtained for the modules in the entry region. The entry length is reduced with an increase in the substrate conductivity. The thermal performance of a turbulent PDF module is found to be linearly dependent on Re...