Numerical study on heat dissipation performance of a lithium-ion battery module based on immersion cooling

Abstract

In order to reduce the maximum temperature and improve the temperature uniformity of the battery module, a battery module composed of sixteen 38120-type lithium-ion batteries is directly immersed in mineral oil to investigate the cooling effectiveness under various conditions of battery spacings (1– 5 mm), coolant flow rates (0.05– 0.35 m/s), and discharge rates (1 C, 2 C, 3C) by means of the commercial Computational Fluid Dynamics software FLUENT. The simulation model is validated by the experimental data of a single adiabatic bare battery in the literature, and the current battery thermal management system based on immersion cooling can effectively improve the heat dissipation of the battery module. As the battery spacing increases from 1 mm to 5 mm, the maximum temperature rise of the battery module decreases by 29%, and the temperature difference is reduced from 7.2°C to 5.2°C. Although increasing the flow rate up to 0.35 m/s can reduce the temperature rise of the battery to 4.07°C, monotonically increasing pressure drop also imposes restriction on the cooling efficiency of the system. When the flow rate is 0.2 m/s, the temperature difference of the battery module is 4.66°C, which can be maintained within a safe threshold. The maximum temperature rise at 1 C, 2 C and 3 C discharge rates is 2.67°C, 5.41°C and 8.69°C, respectively, which are reduced by 40%, 45% and 38% compared with natural convection. The findings above provide more insights into the oil-immersed battery cooling system, and may stimulate the currently popular BTMSs based on immersion cooling.