Numerical Analysis of the Thermal Performance in a Five-by-Five Battery Pack Configured With the Phase Change Material and Optimized Fin Layout

Abstract

Batteries employed in electric vehicles are important components due to their significant high heat capacity and energy density characteristics. However, these batteries experience drastic temperature rise due to the high heat generation, which is basically affected due to different discharge rates. To reduce this, phase change materials (PCMs) are employed around the batteries as they possess high heat latent capacity, compactness, and lightweight nature without the necessity of additional power. In the present study, the heat transfer characteristics of a battery pack consisting of 25 batteries are arranged in a pack with paraffin as the PCM around the battery cells. In the first part of the work, analysis is carried out with and without paraffin by varying the discharge rates to evaluate the thermal characteristics. It is observed that with the increase in the discharge rates greater quantity of heat is accumulated near to the battery cells, this is due to the limited heat-conducting capabilities of the PCM. To avoid this, different fin configurations are designed and studied by varying the discharge rates to study the melting fraction and average temperature distribution within the pack. Results reported that the M3 fin layout developed most effective in reducing the interior heat buildup while maintaining an optimal melting time. Additional examination of the discharge rates at varying rates includes the influence of rest intervals, convection, and fin configurations. The results indicate that implementing rest intervals and augmenting convection not only diminishes the peak temperature but also enhances the recovery of the PCM's melting portion. Fin structures marginally affect the thermal performance in low convection scenarios, resulting in a 9.23% decrease in maximum temperature with greater convection.