An experimental and numerical investigation of heat transfer enhancement in annular microchannel heat sinks

The uniformity of substrate temperature is an important factor to be considered in the design of microchannel heat sink which has been widely used in the micro-channel reactors, electric chip cooling and various type fuel cells. Therefore, two novel annular microchannel heat sink designs are proposed to improve the flow distribution and substrate temperature uniformity of the microchannel heat sink. One is the MRNH design which is the plain configuration; another is the MRSH design which is the enhanced configuration of the MRNH design. Firstly, the values of Nusselt number and pressure drop of the MRNH with the interleaved inlets and outlets are numerically and experimentally examined. It shows that the simulated results are consistent with the experimental results. Then, the influences of two different arrangements of the inlets and outlets on the performance of the MRNH are numerically compared. The result shows that temperature uniformity of the interleaved arrangement is better than that of the sequential arrangement. Finally, the comparison of the performance of MRSH and MRNH designs, and the effects of the geometric parameters of MRSH are numerically investigated. The MRSH design has better temperature substrate temperature uniformity compared to MRNH design. Thermal resistances in the MRSH design are smaller than those in MRNH. The total thermal resistances increase with the increase of slant angle for MRSH design. The maximum total thermal resistances are reduced by 9.5% when the slant angle decreases from 40 degrees to 20 degrees. The Nusselt number increases with increasing the dimensionless width of the oblique channel.