Enhancing high-density battery performance through innovative single-phase spray technology in immersion cooling systems

The flow field organization in liquid-cooled BTMS (Battery Thermal Management System) is crucial to the thermal performance of lithium-ion batteries. This study introduces an innovative single-phase spray technology to optimize the flow field and enhance thermal characteristics in BTMS. Using Computational Fluid Dynamics simulations, key factors such as dielectric fluid type, nozzle diameter, spray angle, and nozzle position are analyzed. Novec 7500 is identified as the optimal dielectric fluid, with thermal conductivity and viscosity playing significant roles. Response Surface Analysis and the entropy weight TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) determine optimal conditions: a 0.47 mm nozzle diameter, 0 mm nozzle offset, and an 88.16° spray angle. These parameters reduce the maximum battery temperature to 25.43 °C and minimize the temperature gradient to 3.41 °C, achieving reductions of 14.20 % and 57.74 %, respectively, compared to non-spray systems. Furthermore, the system reduces the maximum temperature of a 36-cell battery module by 27.28 % to 25.33 °C and the maximum temperature difference by 69.39 % to 4.35 °C. The optimized spray cooling technology is effective for smaller battery stacks and demonstrates the potential to maintain high cooling efficiency in complex systems, providing a solution for BTMS.