Multivariable analysis of vortex generator-aided heat transfer enhancement for 18650 battery thermal management system

Abstract

Currently, electric vehicles and hybrid cars have emerged as global solutions to replace internal combustion engine vehicles, with lithium-ion batteries being the most widely chosen option due to their low discharge rates and high energy density. Air-cooling systems, recognized for their cost-effectiveness and stability, are extensively employed in the thermal management systems of automotive batteries. However, conventional air-cooling models exhibit drawbacks in uniformly cooling battery packs. In this study, a numerical investigation is conducted to explore the enhanced cooling heat transfer facilitated by a vortex generator in the air-cooled battery thermal management system. The heat generation and transfer of a battery pack are analyzed using the experimentally validated 2C discharge heat dissipation model for batteries. The assessment focuses on the impact of a vortex generator on the heat transfer performance of a series-connected battery pack. The results indicate that fluid mixing, boundary layer modification, and flow instability are the primary factors contributing to enhanced heat transfer. Through the utilization of orthogonal experimental design and fuzzy grey relational analysis, the influence of three parameters (vortex generator position, angle of attack, and fin height) on thermal performance was systematically analyzed. The analysis reveals that the vortex generator position exerts the most significant impact on the heat transfer index, followed by height, with the angle having the least effect. Nusselt number and entropy generation were chosen as optimization indicators for a comparative analysis of enhancing heat transfer with and without optimized vortex generator assistance. The research results demonstrate that the optimal scenario occurs when entropy generation is minimized, resulting in a 56.4 % reduction in temperature difference (2.66 K) and a 12.1 % decrease in the maximum temperature (2.75 K). This study provides valuable guidance for further optimizing battery thermal management.