Heat Transfer Enhancement in Heat Pipe Applications Using Surface Coating

The heat dissipated by convection from a finned cooling thermal unit is strongly limited by the poor heat transfer at the airside. A lot of work has been done to enhance the heat transfer coefficient at the airside by changing the fin roughness. The present experimental study demonstrates how a significant enhancement in the overall heat transfer coefficient from a fin can be achieved by applying a more conductive coating on the fin surface. Results clearly show the performance of a finned heat pipe unit built to cool a server chip exhibits better enhancement in the case of a smooth diamond-like carbon (DLC) coating than a rougher one made of diamond particles. The orientation of the heat pipe was also investigated to demonstrate the effect of gravity on the enhancement. The hydrodynamics inside the heat pipe was considered to explain the findings.