Multi-objective optimization of a combined heat sink with triangular protrusion and corrugated surface impinged by a nanofluid slit-confined jet

Abstract

Improving temperature uniformity and heat transfer capacity is crucial for the application of a jet-impingement heat sink in dissipating heat from high-power electronic devices. Therefore, a combined heat sink with a triangular protrusion in the stagnation zone, a corrugated surface in the wall-jet zone, and an oblique angle of the upper plate impinged by a nanofluid jet is proposed. A two-dimensional model is established, using Al2O3-H2O nanofluid as coolant. The effects of the structural parameters of the heat sink, the volume fraction of the nanofluid on the temperature uniformity of the heat sink and the jet-impingement heat transfer were studied numerically. Meanwhile, the structure of the heat sink is optimized by the NSGA-II genetic algorithm. The results indicate that the three structures can enhance both the temperature uniformity and the heat-transfer capacity. Using nanofluids with a 3%volume fraction and a Reynolds number of 8,000, the average Nusselt number of the optimal structure is 26 % greater than that of a jet impingement flat heat sink, the temperature standard deviation is 67 % less, and the friction coefficient and thermal-hydraulic performance factor are greater by 55 % and 9 %, respectively. Meanwhile, the optimized structure exhibits excellent heat dissipation and temperature uniformity at higher heat flux. The allowable maximum heat flux reaches 341 W/cm2 when the junction temperature of the hot spot does not exceed 348 K, and the temperature standard deviation is 2.926, which are increase by 83 % and decrease by 36 % compared with that of jet-impingement plate heat sink, respectively.