An ultrasonic-assisted nanofluid immersion cooling system and its optimization for lithium-ion battery

To fully enhance the heat transfer efficiency and maintain the optimal thermal performance of the battery system, an innovative battery thermal management system (BTMS) is presented where the immersion cooling is enhanced through the integration of ultrasonic excitation and nanoparticle dispersion. A microchannel-based submerged cooling configuration is designed, in which dielectric base fluid is infused with insulating diamond nanoparticles at optimized concentrations. Besides, the heat dissipation efficiency is amplified by ultrasonically induced fluid perturbation mechanisms. Experimental evaluation is systematically performed to distinct operational influences on thermal behavior using isolated variable methodology. On this basis, the multi-factor correlative analysis is conducted based on the design cases, and the surrogate model is constructed with the least square support vector regression (LSSVR) to depict the relationship between the influencing factors and objectives. The proposed BTMS is optimized comprehensively by Non-dominated Sorting Genetic Algorithm II (NSGA-II) algorithm. The experimental results demonstrate that the optimized BTMS exhibits superior performance in both heat transfer efficiency and system temperature uniformity compared to the original system. The maximum temperature is limited to 35.2 °C, and the maximum temperature difference can be controlled within 1.6 °C at 3C discharge rate.