Optimization of an innovative cooling system for motorsport application

• A Formula SAE vehicle battery pack with cylindrical cell battery modules with forced-air cooling was designed and implemented. The cooling system was simulated with CFD and then tested on the track, but the thermal management might not be sufficient at high ambient temperature (35°C) • A supplementary cooling method was then devised with phase change material, PCM, with melting temperature at 40°C • The PCM cooling system was then simulated and then implemented and allowed the cell temperature to be maintained below 50°C even at an ambient temperature of 35°C, enabling the Endurance test to be completed in an optimal manner, demonstrating the effectiveness of the mixed forced air - PCM cooling system. One of the most critical issues in electric vehicle engineering concerns the thermal management of the battery pack, especially in high-performance applications, which are increasingly demanded by the market. Very interesting, from this point of view, is the study of motorsport applications, almost always characterized by a high ratio between power output and energy stored in the battery pack, which makes the problem of thermal management particularly important. It should be noted that motorsports applications typically have a particularly demanding trend of current discharging and charging from the battery pack, with numerous positive and negative peaks at high c-rates; this obviously produces, due to the Joule effect, a much higher amount of heat per kWh than in conventional road cars and therefore makes efficient and high-performance thermal management very important. In this work was defined, analyzed and optimized an innovative mixed solution with forced air cooling and PCM material (phase change material) for high performance battery modules with cylindrical cells used in a Formula Student car. In the various battery thermal management technologies, Air cooling is one of the most used solutions and can be successfully integrated with PCM cooling technique. In the work proposed here, the optimization and numerical simulation of different solutions and configurations is described. The target parameters considered are: airflow rate, cell spacing and mass of PCM. Fluid dynamic simulations were used to identify the optimal value of the radial gap between the cells, a fundamental construction parameter, and the speed of the air coming out of the fans. The choice of the mass of the PCM sheets was made on the basis of the quantity of heat to be removed to obtain a significant effect on the final temperature of the cells during the test (<50°C) and compatibly with the spaces available between the modules inside the battery pack. The simulations of the optimal solution will be compared to experimental results for validation, by the realization of the most promising configuration and its real experimentation on the car, in order to validate the expected performance of the thermal management system.