Comprehensive thermal performance analysis of an air-cooled staggered configured Li-ion battery pack- A numerical and experimental approach

Abstract

The discharge rate, ambient temperature, and airflow cooling velocity of a Li-ion battery pack BTMS have a direct impact on the battery's temperature, performance, and safety. Monitoring these is essential for avoiding overheating, ensuring optimal performance, and extending the battery's lifespan. This study comprehensively assesses the thermal performance of staggered structured cells of a 24.00V, 10.00Ah Li-ion battery pack cooled by ambient air. Both experimental and numerical methods are employed to achieve this evaluation. The primary objective is to investigate how varying discharge rates (0.50, 1.00, 1.50, 2.00, and 2.50; C), the seasonal temperatures in Prayagraj, India (282.00, 296.00, 305.00, and 315.00; K), and airflow velocities (0.50, 1.00, 1.50, and 2.00; m/s) influence the battery pack's thermal behaviour. A comparative analysis is also conducted between the present study and the author's prior research, focusing on the aligned configuration. The study observed a temperature increase in the airflow direction, from the inlet to the outlet, with the highest temperature recorded in the second-to-last column of the battery pack. Both numerical analysis and experimental testing confirmed that decreasing the airflow velocity from 2.00 m/s to 0.50 m/s reduced thermal performance by enhancing temperature in the airflow path, as well as transverse and circumferential temperature variations. Conversely, as the load on the battery (discharge rate) decreased from 2.50 C to 0.50 C, the thermal performance estimating parameters; Tmax, Tavg., ΔTmax, and σT, exhibited a declined trend. This is due to the greater heat generation at higher discharge rates. Furthermore, it was observed that as the ambient temperature increased from 282.00 K to 315.00 K, the temperature of the battery cells also increased. Nonetheless, the cooling patterns remained similar across these different temperature range conditions. Moreover, experimental results compete with the numerical outcomes with a maximum absolute percentage error of 1.21%. The staggered configuration gives lower and uniform temperature distributions within the battery packs than the aligned arrangements.