Multi-objective optimization of an offset strip fin heat exchanger for waste heat recovery in electric vehicles

To increase short driving range of electric vehicle, it is important to reduce power consumption of heat pump system. In this study, an offset strip fin heat exchanger with perpendicular flow is investigated to improve the performance of an electric vehicle heat pump using waste heat. The correlations of the Colburn and friction factor are developed using the experimental data. The simulation results are compared to the experimental results and are validated within temperature and pressure errors of 1.51% and 1.55%, respectively. A multi-objective optimization is performed to maximize the thermal–hydraulic performance of the offset strip fin heat exchanger with six independent design variables via the approximation-assisted optimization technique. The five optimal designs exhibit a 3.7% increase in the heat transfer rate and a 42.1% decrease in the pressure drop for the main simulation condition. Sensitivity analysis and parametric studies are conducted to analyze the effects of each design variable. The results reveal that the fin wrinkle angle, fin height, fin length, and fin spacing had a significant impact on the thermal–hydraulic performance of the offset strip fin heat exchanger.