Novel converging-diverging microchannel heat sink with porous fins for combined thermo-hydraulic performance

Abstract

The optimum design of the microchannel heat sinks needs to consider both the heat transfer and pressure drop limitations of the microchannel. In this paper, a novel configuration of the microchannel heat sink is proposed to obtain improved thermo-hydraulic performance. The proposed microchannel includes porous fins that form adjacent converging-diverging channels. Three-dimensional steady laminar simulations were conducted to access the performance of this novel microchannel and compare it with the conventional parallel ones with porous and solid fins. The results showed that by using this novel design, a 9.75% decrease in pressure drop is observed when compared to conventional solid fin parallel microchannel. Also, the mean Nusselt number of the microchannel heat sink with converging-diverging porous fins showed a maximum improvement of 16.5% compared to the parallel microchannel with solid fins. The overall thermo-hydraulic performance evaluation factor of the converging-diverging microchannel showed also a significant 20% improvement compared to conventional designs. The analysis of the flow fields showed that the converging-diverging design with porous fins leads to a local pressure difference between two adjacent neighboring channels inducing a cross-wise velocity component within the porous fins leading to enhanced thermal performance. Moreover, it was shown that only for converging-diverging angles above 0.5 °, performance enhancement was observed compared with a microchannel with solid fins showing the existence of an optimum range for converging-diverging angles. The response surface method was used to find the optimum range of fin porosity and converging-diverging angle where the performance of the microchannel heat sink is maximum.