Numerical study on flow and heat transfer characteristics in manifold microchannel heat sinks with rectangular restrictors

Abstract

The Z-type manifold microchannel (MMC) heat sink could efficiently dissipate the heat for electronic devices. However, this structure has a drawback of non-uniform flow distribution. To enhance the flow uniformity, three optimization schemes are proposed in this study. The first one is to add a rectangular restrictor in each microchannel and the rectangular restrictor width is set to an uneven size. The second one is to add a rectangular restrictor on the top of each fin and the gap of adjacent rectangular restrictors is set into uneven dimensions. The third one is to set the width of each microchannel into uneven dimensions. The influences of the rectangular restrictor height and the microchannel widths on the flow and heat transfer characteristics have been numerically investigated. The results show that the MMC with uneven microchannel width exhibits the best flow uniformity and minimum thermal resistance. The flow uniformity factors of the three optimization schemes are all below 13.35% and the MMC with uneven microchannel widths has the lowest flow uniformity factor of 7.87%. The flow uniformity of the MMC with uneven microchannel widths is improved by 84.88%, and the thermal resistance of the case is reduced by an average of 21.67%. On the other hand, the flow uniformity of the MMCs with restrictors in each microchannel and on the top of each fin is improved by 74.34% and 80.53%, respectively. The thermal resistance of the two cases is reduced by 9.74% and 11.22%, respectively. Moreover, the pressure drops of the three optimized MMCs are relatively similar in magnitude.