Secondary heat transfer enhancement design of manifold microchannels based on entransy theory

Abstract

Manifold microchannel heat sinks (M-MHSs) are preferred solutions for ultrahigh heat flux heat dissipation in electronic chips. To further enhance heat transfer, the heat transfer mechanism of M-MHS was studied based on entransy theory, and a manifold and fractal coupling microchannel heat sink (MF-MHS) was proposed. The results revealed that the M-MHS can enhance heat transfer, which is attributed mainly to the impact effect and chaos flow caused by the transition of fluid from the manifold to the microchannel, leading to a greater entransy gain and lower entransy dissipation in the channel centre and near the channel wall. The proposed MF-MHS can further improve the entransy gain and decrease the entransy dissipation, thus enhancing heat transfer. Under the same Reynolds number, the comprehensive performance of the MF-MHS increased the convective heat transfer efficiency by 1.6 %-3.3 %. Finally, a reinforcement factor was proposed to evaluate the coupling effect on heat and mass transfer. The results revealed that although the MF-MHS can enhance convective heat transfer, the manifold-microchannel coupling effect will suppress the convective heat transfer performance. This work might provide guidance for the heat transfer mechanism analysis and active design for MHSs.