Battery thermal management system analysis on electric vehicles

Abstract

Battery thermal management systems (BTMS) on electric vehicles are crucial for efficiently managing battery temperature. The development of BTMS has been a crucial part of the commercialization of electric vehicles. The efficiency of the BTMS has become a bottleneck to increasing the battery's charging and discharging rates. Hence, this study aims to examine the impact of cell arrangement and the type of coolant used on the BTMS performance, and also to identify the most suitable setup for the current module. This study uses Ansys as the Computational Fluid Dynamics (Csoftware to simulate the cooling of a battery module with 96 units of 21700 cylindrical cells by immersion cooling BTMS. Two cell arrangements and three types of coolant have been simulated to identify the impacts on the performance of the BTMS. The flow speed of the coolant is set to 0.0020 m s−1, 0.0045 m s−1, 0.01 m s−1, 0.015 m s−1, and 0.02 m s−1 to analyse the impact of the setup at different inlet velocities. The inlet velocity is set to a constant at the inlet of the module without considering the pressure loss coming from the pump to simplify the study. The result indicates that the aligned module has reduced the maximum module temperature and module temperature gradient by 7.91% and 24.64%, respectively. For the coolant, water shows its superior cooling performance, which reduces the maximum temperature and temperature gradient of the module by 17.61% and 63.77%, respectively. The Analytic Hierarchy Process indicates the same decision, where water is the most suitable alternative for the given criterion in this study. However, water has significant safety issues where it can cause battery circuit shortage when it is polluted with ions. The study recommends that future studies consider additional criteria in terms of safety and lifespan for the AHP, and also to apply more detailed geometry for the module in order to achieve more practical results.