Numerical analysis of 3-D laminar natural convection heat transfer from solid vertical cylindrical heat sinks with straight longitudinal fins and comparison with horizontal heat sinks of the same configuration

Of the various challenges facing the electronics industry, keeping components cool is utmost important, since overheating reduces the reliability and operating life of a device. Among various cooling methods, natural convection has been deemed fit owing to its distinctive advantages over forced convection. Longitudinal fins are generally used for vertical cylindrical heat sinks since the geometry eases air flow between successive fins. In the present study, CFD analysis of conjugate natural convection from such heat sinks have been carried out in the laminar regime. 15 different heat sinks modelling heat sinks of LED bulbs of dimensions obtained from literature have been developed. Effect of non dimensional fin spacing, fin length and Rayleigh number on the thermal resistance of the heat sink have been studied and values compared with those of horizontal sinks available in literature. It is observed that compared to the horizontal sink, the thermal resistance of the vertical sink is decreased by different percentages for different configurations. Contour plots to capture temperature profiles around the vertical heat sink have been developed. Correlations for Nusselt number have been formulated which are found to show appreciable agreement with computational data.