Hydrothermal performances of symmetric and asymmetric divergent-convergent microchannel heat sinks

Abstract

The present work numerically studied the hydrothermal performance of symmetric and asymmetric divergent-convergent microchannel heat sink (DCMCHS) with the rectangular cross-section. Three different DCMCHS with fixed total channel volume were designed, the symmetric DCMCHS, the width-asymmetric DCMCHS with the fixed inlet-to-middle cross-sectional width ratio, and the width-asymmetric DCMCHS with the fixed middle cross-sectional width. Effects of the inlet-to-middle cross-sectional width ratio and channel height of the symmetric DCMCHS, and the outlet-to-inlet width ratio, the middle cross-sectional width and the channel height of the width-asymmetric DCMCHSs on the maximum temperature, overall thermal resistance, pressure drop, and the coefficient of performance (COP) of the DCMCHSs were analyzed. It was found that the symmetric DCMCHS with smaller inlet-to-middle width ratio has smaller thermal resistance but larger pressure drop. Moreover, the decreasing outlet-to-inlet width ratio can improve the thermal performance of the two width-asymmetric DCMCHSs and increase the pressure drop. The increasing middle cross-sectional width can reduce the thermal resistance of width-asymmetric DCMCHS with fixed channel height and fixed outlet-to-inlet width ratio by consuming more pressure drop. For the COP, all the proposed DCMCHSs in the present work have smaller COP compared with the conventional parallel MCHS.