Experimental and numerical investigation of the LiFePO4 battery cooling by natural convection

In this study, the thermal performance of a LiFePO4 (LFP) pouch type battery in the range of 1C-5C discharge rate at 23 degrees C ambient temperature and natural convection conditions is experimentally and numerically investigated. Time-dependent temperature changes of the battery are imaged with a thermal camera for each discharge, and the maximum, minimum and average changes on the battery surface are examined. In addition, the heat transfer rate through the battery is calculated for each discharge rate under natural convection conditions of the battery, and the temperature and velocity distributions on the battery surface are investigated. For the experiment with the highest discharge rate (5C), the measured maximum and average battery temperatures are determined as 52.2 degrees C and 50.1 degrees C, respectively. The calculated maximum temperature difference on the battery surface is also 6.7 degrees C. Moreover, the homogeneity index defined for battery surface temperature is 0.147 at 5C discharge rate. It has been observed that natural convection cooling is not sufficient for the battery at high discharge rates Furthermore, a new correlation equation has been proposed for the estimation of the heat transfer rate from a 20 Ah LFP pouch type battery under natural convection conditions at 23 degrees C ambient temperature.