Analysis of free convection in heatsinks using design of experiments

Abstract

Heatsinks are finned metal parts capable of reducing the operating temperature of equipment in the most diverse engineering areas. With the increasing miniaturization of electronic equipment, more efficient, long lasting heatsinks are necessary. In this study, analyses of different geometric parameters in rectangular finned heatsinks were performed. The variables studied are: the average heat transfer coefficient, h̅, the dimensions of the base, the geometric parameters (height and spacing between fins) and position of heatsinks. In addition, analyses with different heat flux intensities applied to the heatsink bases were accomplished. All possible variations involved in the experiments were developed using the DOE (Design of Experiments) statistical tool, together with Minitab software, in order to obtain a statistical analysis of the results. Tests were carried out with 8 different heatsinks, 4 with 50 mm x 50 mm and 4 with 100 mm x 100 mm base area. Two height and fin space values were analyzed for each heatsink. A sequence of 64 experiments involving all variables was done. Experimental temperature data, h̅ obtained experimentally and Nusselt number were used in the analyses. Empirical correlations found in literature were used to validate the results and equally good results were obtained. Finally, a statistical analysis was performed by using Minitab software with the aim of finding the interactions of the variables previously mentioned in relation to Nusselt number.