Parametric Study of Pin Length and Reynolds Number Effects on Heat Transfer in a Cast Pin Fin Coldwall for Electronic Systems

At low to moderate Reynolds numbers, cast pin fin coldwalls provide an excellent combination of performance and low unit cost for air-cooled electronic systems. The purpose of the paper is to study the details of the fluid dynamics in order to better understand the heat transfer performance within the flow regime appropriate for cast pin fin coldwalls. A parametric study is presented examining the variation in the Nusselt number over a range of pin lengths and Reynolds numbers. The numerical study uses a five-pin cell to simulate an embedded flow pattern within a large array of staggered pin fins. The modeling technique was previously validated using experimental data. Performance comparisons are made for pin length-to-pin diameter ratios of 2 ≤ L/d ≤ 6 and for 200 ≤ Red ≤ 2000. Conclusions are drawn assessing the effects of the fluid dynamics, such as the horseshoe vortices formed at the pin-wall interface, on the local heat transfer mechanisms. Effects of the pin spacing were addressed by a previous experimental study.