Simulation Driven Thermal Optimization of an Innovative Battery System

BATSS project objective is to design a safe, effective and sustainable battery pack. To achieve this, the battery system (BS) will be mechanically, electrically and thermally optimized using cutting edge technology. Consequently, the battery system includes innovative 4695 cylindrical cells and advanced thermal management, carried out with the Miba FLEXCOOLER®. This work focuses on the BS thermal optimization using system simulation tools. First a simplified version of the BS is simulated with all physical phenomena involved in thermal behavior to identify first order parameters. It appears that various BS component and heat transfer can be neglected in comparison with the heat transfer due to cooling system. Then the simulation of the full battery system is conducted under nominal condition. Cooling system appears to be performant as it allows a controlled averaged temperature and very low cell-to-cell temperature variability. Finally, impact of both design and operating parameters is evaluated. Simulation shows that the coolant mass flow can be reduced by 70% from its nominal value allowing to maintain good thermal performances while reducing the pressure drop in the cooling system. Impact of the Miba FLEXCOOLER® / cell surface exchange is also investigated. Results demonstrate that increasing exchange surface reduces averaged temperature in the pack but slightly increases cell temperature heterogeneities.