Natural convective heat transfer from a heated horizontal disc with heated hollow cylinders: Effect of flow characteristics around heated cylinders with a gap

Abstract

The natural convective heat transfer from a heated horizontal disc with gapped heated hollow cylinders was investigated experimentally, forming the foundation for improving the cooling performance of the heat sinks. The cooling target for this study was the central area of the heated horizontal disc where the heat dissipation was low. The heat transfer was greatly enhanced by the reversal of the flow from the gap between the heated hollow cylinders towards the heated horizontal disc. The reverse flow was promoted by the conditions of a narrow clearance between the heated horizontal disc and the heated hollow cylinder and a wide gap between the heated hollow cylinders. Conversely, for the flow along the heated horizontal disc, the heat transfer showed improvement by increasing the clearance between the heated horizontal disc and the heated hollow cylinder. The relationship between the heat transfer and flow properties was demonstrated using the Nusselt number of the heated horizontal disc and the Rayleigh number corrected for the ratio of the heated hollow cylinder height to the clearance between the heated horizontal disc and the heated hollow cylinder.