Numerical Investigation of the Direct Liquid Cooling of a Fast-Charging Lithium-Ion Battery Pack in Hydrofluoroether

Battery thermal management systems are critically important for ensuring the safety and prolonging the lifetime of lithium-ion batteries in electrical vehicles, especially those under fast charging. In this paper, a novel direct liquid battery cooling system based on a hydrofluoroether (HFE-6120) coolant is proposed for fast-charging battery packs. This paper numerically investigates the critical parameters in direct liquid cooling (DLC) with high-fidelity computational fluid dynamics (CFD) simulations. The results show that the DLC with a full-size channel design and high flow velocity control has a redundant cooling performance with the problems of low energy density and high power consumption, which can be resolved through optimization. First, when designed with a partial height channel and controlled with an appropriate coolant velocity, the mass energy density can be improved by up to 20.3% and the power consumption can be reduced by 95.3% compared to the selected baseline. Second, the maximum temperature difference and temperature standard deviation can be reduced by 18.1% and 25.0%, respectively, with a multilayer structure and cross-flowing configuration. These findings establish an improved understanding of the key parameters of DLC systems and provide guidelines for the design of direct liquid battery cooling.