Performance optimiation of a cylindrical mini-channel heat sink using hybrid straight-wavy channel

The problem of high pressure drop remains a challenge in the design of heat sinks using the passive techniques of heat transfer enhancement. Wavy channels are widely used to improve the transfer of a mini-channel heat sink but with an undesirable pressure drop. A new channel design was proposed to enhance the performance of a cylindrical mini-channel heat sink (CMCHS) with a minimal possible pressure drop. The design was a straight-wavy hybrid channel, in which the channel path changes from straight at the entrance of the CMCHS to wavy. 3D computational fluid dynamics was performed to analye the fluid flow and heat transfer of the CMCHS. Simulation was conducted on the CMCHS water with a Reynolds number of less than 500. On the basis of entropy generation minimiation technique, CMCHS performance was optimied using different geometric parameters. The parameters included entrance channel length ratio and the wave amplitude ratios of the second and third sections of the channel. A test rig was manufactured to test CMCHSs for a wide range of operating conditions to validate the simulation model. Two models of CMCHS with straight and hybrid straight-wavy channels were developed on the basis of the optimum dimensions acquired from the numerical prediction. Results revealed that the overall performance of the CMCHS with a straight-wavy channel is better than that with a straight channel under the same operating conditions. The straight-wavy channel is more effective than the conventional straight channel in reducing the maximum surface temperature along the channel length of the CMCHS. The temperature uniformity along the CMCHS with a straight-wavy channel is better than that with a straight channel.