Numerical study on heat dissipation and structure optimization of immersed liquid cooling mode used in 280Ah LiFePO4 batteries

Efficient thermal management can ensure the lithium-ion batteries to operate steadily and long-term, among which immersion liquid cooling with higher cooling power and battery module temperature consistency presents great potential. According to the different heat transfer methods, three forms of immersion liquid cooling can be distinguished: static flow immersion cooling (SFIC), forced flow immersion cooling (FFIC), and immersion coupled direct cooling (ICDC). In this study, the numerical model is first established to comprehensively compare the cooling characteristics of the three modes, and the effects of the battery spacing, inlet relative locations and thermal characteristics of the coolant on the FFIC mode were further investigated. The results show that the maximum temperatures of SFIC, FFIC, and ICDC are reduced by 4.23%, 5.70% and 13.29%, respectively, compared to natural convection conditions. The FFIC mode has highest sensitivity to the flow parameters of the coolant, indicating that the heat dissipation capability could be moderated by proper temperature control strategies. The UTTB structure is more efficient at dissipating heat as coolant enters from the upper section of the batteries and exits from both sides. It is also revealed that increasing the thermal conductivity and specific heat capacity of the coolant to 0.6 W/(m∙K) and 1500 J/(kg∙K), respectively, at a flow rate of 0.03 m/s enables the battery module maximum temperature to reduce by 2.78% and 6.20%. However, given the challenge of attaining effective coolant thermal characteristics, the combination of active control methods, such as regulating the flow parameters of the coolant, will be a more economically feasible method in the future.