Experimental Assessment of Different Air-Based Battery Thermal Management System for Lithium-Ion Battery Pack

Abstract

<div>Lithium-ion (LI) batteries are widely used to power electric vehicles (EVs), owing to their high charge density, to minimize the environmental pollution caused by fossil fuel-based engines. It experiences an enormous amount of heat generation during charging and discharging cycles, which results in higher operating temperatures and thermal nonuniformity. This affects performance, useful battery life, and operating costs. This can be mitigated by an effective battery thermal management system (BTMS) to dissipate the heat there by safeguarding the battery from adverse thermal effects and ensuring high performance, safety, and longevity of the battery. This article presents a method to estimate the cooling requirement of a given battery pack using calorimetry and discusses the effect of airflow path, flow rate, and inlet air temperature on the thermal behavior of a 4S4P battery pack consisting of 18650 type lithium iron phosphate (LFP) cylindrical Li-ion cells each of 2.55 Ah capacity. In battery pack operation without a cooling system, it is found that the interior cells experience a 3°C higher cell temperature relative to the rest of the battery pack. The cooling performance of the different air BTMS, viz., natural convection cooling, single suction fan cooling, two-fan air cooling, centralized inlet air cooling, and wet jute-based single suction fan air cooling, is discussed. It is observed that the peak temperature rise of the cells in the battery pack was found to be the least in centralized inlet air cooling, unlike other cooling configurations. The wet jute-based single suction fan air cooling is superior by achieving the highest COP of 6, with an 8.9°C rise in battery pack peak temperature for a permissible peak discharge rate. It is observed that the temperature rise of the battery pack is profoundly influenced by the temperature of the inlet air compared to the flow rate.</div>