FORCED CONVECTION HEAT TRANSFER OF AXIAL AIR FLOW WITH HEATSINK ON UNIFORM HEAT FLUX

Abstract

The heat sink is used to increase heat transfer from heated surface to air. The seize and the geometry of the fins affect on the heat transfer coefficient. The heat transfer prediction represents the first step to get the optimal design. The purpose of the present study is to predict the effectiveness of two types of closely spaced fins, the first arrangement is parallel cylindrical fin array and the second type is hollow parallel cylindrical fin array. Also there are two types of heat sink with respect to the fan location, the first type is the cooling fan attached in order to draw the hot air up and away from the heatsink fixed outside on the heat sink to let the axial air flow and the other with enclosure cutout template. The heat sink geometry are designed with Solidworks 14 and exported to ANSYS FLUENT 15.0.7 CFD code. Reynolds number were taken at a range 4000-16000, so k-Ԑ model turbulence model was used in to simulate mean flow characteristics for turbulent flow conditions. Constant heat flux condition was proposed with range between 1000-10000 kW/m2. The Results of temperature contour lines depicted a variation from the base to the extended surfaces tips especially with the fins from outside to the core of the heat sink. This explain that the heat sink with a cooling fan fixed in the enclosure cutout template more effect than the second type with second fan fixation for the two types of fins. Nusselt numbers indicated that cylindrical fins performed better in heat transfer than the hollow fins.