Thermal and hydrodynamic characteristics of single-phase flow in manifold microchannels with countercurrent regions

Abstract

Manifold microchannel heat sink is promising to dissipate high heat fluxes for electronic devices due to its high surface to volume ratio. Traditional Z-type manifold encounters fluid flow maldistribution and a high temperature difference. In this work, two inlets and countercurrent flows are introduced into the manifold arrangement to alleviate these problems in the Z-type manifold microchannels. Six cases with different manifold arrangements are numerically investigated using single-phase HFE-7100 at mass flow rates ranging from 56.8 to 117.78 mg/s. The results show that the maximum temperature, average temperature, and temperature difference of the revised arrangements are all lower than these of the traditional Z-type manifold arrangement. The minimum temperature difference for an ideal multi inlet manifold arrangement can be less than 0.2 K, while the value is about 5.3 K for the traditional Z-type manifold arrangement. The revised arrangement can also improve the uniformity of mass flux distributions. The ratio of the maximum to the minimum mass flux within microchannels is 12.83 for the traditional Z-type manifold, while this value is about 5.82 for cases with two inlets and countercurrent zones. A longer flow path and a higher local pressure drop in the revised arrangements results in higher pressure drops than the traditional Z-type manifold microchannels. Compared with the traditional Z-type arrangement, heat transfer coefficients and performance evaluation criterion are higher for the improved cases. The presence of a countercurrent zone can improve the comprehensive performance of the manifold microchannel. New criterion based on the thermal resistance calculated at the maximum temperature is proposed to evaluate the cooling performance of electronics.