Numerical investigation of vertical vibration effects on immersion cooling heat transfer for lithium-ion battery at high discharge rate

Liquid immersion cooling is a promising thermal management strategy for lithium-ion batteries in electric vehicles. While vertical mechanical vibration inherent to vehicular operation can enhance heat transfer, its effects on immersion cooling systems remain underexplored. Using numerical simulation, this study investigates the heat transfer characteristics of immersion-cooled lithium-ion batteries under vertical vibration (with frequencies of 0–20 Hz and amplitudes of 0–5 mm) at high discharge rate (4C) systematically. Results shows that increased vibration frequency and amplitude markedly decrease both maximum temperature rise and temperature differentials, effectively suppressing thermal elevation and enhancing battery temperature uniformity. Vibration enhances battery heat transfer by: (1) increasing coolant flow velocity, (2) disruption of thermal boundary layers, and (3) inducing transition from laminar to turbulent flow. This elevates the surface-averaged Nusselt number, thereby increasing the convective heat transfer coefficient between battery surfaces and coolant. Crucially, vibration achieves superior thermal homogeneity across battery surfaces by significantly enhancing cooling performance. A Backpropagation Neural Network (BP-NN) was developed to predict maximum battery temperature rise. This work provides critical insights for optimizing immersion-cooled battery thermal management systems and enhancing safety protocols.