A direct optimization strategy based on field synergy equation for efficient design of battery thermal management system.

• A direct optimization strategy for efficient design of parallel BTMS is developed. • Field synergy equation is employed to obtain the optimal flow rate distribution. • Flow resistance network model is used to directly calculate the optimal parameters. • Experiments are carried out to demonstrate the effectiveness of numerical method. • >The optimized BTMSs in this study exhibited remarkably enhanced cooling performance. Air-cooled battery thermal management system (BTMS) is critical for the safety and performance of electric vehicles. The system design needs to be optimized to achieve best thermal stability and uniformity. The current optimization methods for system design require empirical adjustment and contain randomness, which impedes to get the optimal system design. In this work, a direct optimization strategy based on field synergy equation is proposed for the optimal design of BTMS. Field synergy equation is introduced to calculate the optimal flow rate distribution in the system, which is combined with flow resistance network model to obtain the optimized structural parameters of the system. The developed strategy is adopted to optimize the parallel channel width distribution and plenum angle of BTMS. Computational fluid dynamics method and experiment are utilized to evaluate the cooling performance of BTMS. The results show that the temperature difference (Δ T max) in battery pack after parallel channel width optimization is reduced by at least 49% without pressure drop increased, while Δ T max after plenum angle optimization is reduced by at least 56% with pressure drop slightly increased. Mechanism of convective heat transfer optimization is taken into consideration by using field synergy equation in the proposed direct optimization strategy, which thus eliminates the burden of repeated adjustment of structural parameters and exhibits high efficiency for design of parallel cooling system. The developed optimization strategy is believed to guide the thermal design of battery packs to enhance their performance and safety. [ABSTRACT FROM AUTHOR]