Numerical Investigation on the Suitability of a PCM/Refrigerant Hybrid Cooling System for Lithium-Ion Batteries

Abstract

Abstract As electric vehicles become more prevalent, the need for safe, efficient battery packs will drastically increase. Lithiumion batteries are at the forefront of this technology due to their high voltage, high energy density, long lifespan, and low self-discharge rate. The performance and lifespan of a lithium-ion battery pack is closely related to the temperature of the battery pack. Safety is also a concern as thermal runaway can occur at temperatures above 353K. As a result, battery thermal management systems (BTMS) are required to maintain the temperature at a safe level. The performance of a convective heat transfer and phase change hybrid BTMS has been evaluated numerically using Ansys Fluent. Refrigerant R134a is the primary focus of this paper due to its use in the existing air conditioning system. Its performance is then compared to that of water and air cooling. Paraffin and a paraffin/graphite composite are used as the phase change material (PCM), and their performance is compared to that of aluminum, representing the absence of PCM. Finally, the diameter of the cooling channel is altered to evaluate its effects on heat removal from the battery pack. It was determined that for all cases water cooling was sufficient to keep the batteries within their optimal range. By contrast, there were no circumstances where air cooling was sufficient to keep the batteries beneath their thermal runaway temperature. At higher Thermal Reynold’s numbers, R134a was able to maintain the battery below the thermal runaway temperature but resulted in temperatures well above the optimal operating temperature.