Performance of Rectangular Pin-Fin Heat Sink Subject to an Impinging Air Flow

Abstract

The heat sink is used to enhance heat rejection from heated surface to air. The seize and the geometry of
 the heat sink with the shape of the extended surfaces have a great influence on the heat transfer coefficient. The
 first step to get the optimal design is to predict the heat transfer by conduction in solid walls of heat sink and then
 by convection between the solid and air flow. The purpose of the present study is to predict the effectiveness of
 closely spaced parallel rectangular fin array arrangement. The electronic processor was represented by the copper
 heat sink base with thermal conductivity of 401 W/m.K. The 72 fins with the geometry above mentioned were
 exposed to heat transfer with conduction and convection along all the boundaries except the bottom from which
 heat flow toward air flow domain. Mesh generation at a specific cells, number of element and number of nodes
 were taken under temperature difference validation. The experiments were done under impinging air flow rate
 with Reynolds number ranged between 4000-16000. The flow was turbulent so the k-Ԑ turbulence model needed
 to simulate mean flow characteristics. Constant heat fluxes boundary conditions were proposed with range between
 10000-70000 kW/m2. The Results of temperature contour lines depicted a heat trend from the hot base through the
 extended surfaces to the fin tips. The fins were aligned in the core of heat sink showed higher temperature gradient
 compared with the fins existed in lines surrounded the core. The thermal resistance decreased as the Reynolds
 number increased and the Nusselt number increased as the Reynolds number increased and also when the heat flux
 increased. The Reynolds number depicted increasing as the Nusselt number increased and so the heat rejected
 from the heat sink base increased. There is a good agreement between the experimental and simulating results at
 error percentage not exceed 2%.

Surface modification techniques for cooling by impinging jets-a review

“…Naphon and Wongwises [28] investigated the effect of jet impingement cooling by observing the working temperature of a CPU and observed comparatively lower temperatures. Mohammed and Razuqi [29] studied effects on heat transfer coefficient for a rectangular pin fin heat sink subjected to jet impingement. They concluded that with an increase in the Reynolds number, the thermal resistance decreased, which in turn led to an increase in the average Nusselt number.…”