Geometry parameters optimization for a microchannel heat sink with secondary flow channel

Multi-objective optimization of geometry parameters of a microchannel heat sink with secondary flow channel was performed in this paper. The optimization objective is to minimize the thermal resistance and pumping power of the heat sink under constant water mass flow rate. The design variables include the ratio of secondary channel width to microchannel width ɑ the ratio of half pitch of secondary channel to microchannel width β and the tangent value of secondary channel angle γ. The effects of single key design variable on the objective functions were numerically studied and the K-means clustering analysis was applied for the Pareto optimal solutions. The results show that the design variable α has the biggest influence on both thermal resistance and pump power. The pump power decreases by 13.7% and the thermal resistance increases by 17.2% as ɑ increases from 1 to 2. The design variable β has less influence on objective functions. In the studied γ range, the pump power and the thermal resistance increase by 6.9% and 17.1%, respectively. There is an effective trade-off point between five cluster points of Pareto optimal solutions. In practical design, the structure parameters can be selected from five cluster points according to the pump power available to drive the fluid or required thermal resistance. The performance of the microchannel heat sink with secondary flow channel is significantly improved by optimization of structure parameters. Compared with the conventional smooth channel under the mass flow rate range studied in this paper, the thermal resistance and the pumping power of the optimized microchannel with secondary flow channel can be maximally reduced by 28.7% and 22.9%, respectively.