Secondary heat transfer enhancement design of variable cross-section microchannels based on entransy analysis

Convective heat transfer enhancement is a trade-off between heat transfer enhancement and pumping power reduction. Entransy theory, evaluating the heat transfer efficiency from the viewpoint of irreversibility, is an ideal way to evaluate convective heat transfer performance. In this paper, the entransy dissipation is re recognized from the viewpoints of heat transfer and fluid flow to explain the contradiction between heat transfer entransy dissipation (HTED) and fluid flow entransy dissipation (FFED). The concept of local entransy is introduced to analyze the heat transfer enhancement mechanism of variable cross-section microchannels (VC Ms). Based on the analysis, a secondary design was used to further enhance heat transfer performance. The results found that the secondary design of VC-Ms showed lower entransy dissipation and higher convective heat transfer efficiency, which provided data supporting the optimization and active design of the microchannel heat sink.