Augmentation of natural convection heat sink via using displacement design

Abstract

Miniaturization of electronic devices demands an effective thermal management system for efficient cooling. Still, many electronic industries use natural convection cooling techniques like plate-fin heat sinks as far as no moving part (noise) and reliability is concerned. In this study, the widely-used plate fin heat sink is augmented by a novel fin displacement amid fin array. Yet the effect of fin displacement between alternate fins is experimentally and numerically investigated under natural convection condition. In the meantime, the effects of fin spacing, length, height, and heat flux on the heat sink performance subject to fin displacement is also studied. For the smaller fin pacing, introducing the fin displacement will delay the merging of boundary layers, and reduce the length of fully developed region accordingly. Smaller fin spacing can also entrain the outside air into the fin array at the upper portion of heat sink for offering additional enhancement. The fin displacement is especially effective for a smaller fin spacing. This is because fully developed flow prevails at a smaller fin spacing. On the other hand, the fin displacement may impair the performance when a very wide fin spacing is used. Similarly, the increase in the fin length also enhances the heat transfer performance under the fin displacement conditions. It is also found that the effect of fin height on the thermal performance is small and the effect of heat flux is negligible. The maximum reduction in the thermal resistance is 56% by adopting the displacement design. A drop in fin temperature at the upper portion with the displacement design may lead to a reduction in heat transfer coefficient. For the comparison containing the fixed volume, the heat sink with fin displacement offers a 30% heat transfer enhancement ratio, 28.7% reduction in total mass, and 27.4 % reduction in surface area when compared to the conventional heat sinks.