Direct cooling thermal management of cylindrical batteries using half-helical ducts

For lithium-ion batteries, excessive temperature and nonuniform thermal distribution reduce stability, shorten service life, and may even lead to thermal runaway. To mitigate these issues, this study proposes and optimizes a direct cooling thermal management strategy using R134a with half-helical ducts designed for 18650-type cylindrical batteries. A three-dimensional numerical simulation was conducted to investigate the effects of duct radius and pitch on the cooling process, leading to an optimized duct structure. According to simulations performed with ANSYS Fluent, variations in battery temperature due to duct radius remain within 2 °C, while reducing the duct pitch from 12 mm to 3 mm lowers the maximum temperature and temperature difference by 15.8 °C and 11.0 °C, respectively. Furthermore, three optimized duct arrangements are proposed based on key design principles, including a combination of downstream and upstream flow, adjustment of inlet and outlet distribution, and a gradual change in pitch. These optimizations significantly enhance temperature uniformity, further reducing the temperature difference by 5.62 °C. As a result, the maximum temperature and temperature difference are controlled within 25.15 °C and 3.64 °C, respectively. In summary, the proposed optimization methods effectively regulate and balance temperature, offering new insights and theoretical support for designing direct cooling solutions for similar three-dimensional cylindrical heat sources.