Thermal Performance of Immersion Cooling On Li-Ion Battery with Paraffin Wax-based Phase Change Material (PCM) under Ship Rolling and Pitching Angles

Abstract Battery Thermal Management System (BTMS) onboard electric ships are crucial for optimising battery performance and longevity. By regulating the temperature, these systems ensure that batteries operate within safe limits, thus reducing the risk of thermal runaway. The present work aimed to determine the thermal performance of immersion cooling BTMS using paraffin wax-based PCM as a coolant on a LiFePo4 Li-Ion battery pack at discharging rates of 1C, 2C, and 3C. The immersion coolant rates were set to 30%, 50%, and 90%, and the inclination angles of the simulated ship’s pitching and rolling conditions were 15° and 35°, respectively. It was found that direct immersion cooling by paraffin PCM significantly affects the lowering of the battery pack’s discharging temperature. Discharging the battery without a coolant resulted in a battery temperature of 45.38 °C, above the safe limit temperature of 40°C for LiFePo4. Meanwhile, discharging the battery pack immersed in paraffin PCM reduced the temperature by approximately 6 - 7 °C at 30% immersion, 8 - 10° C at 50% immersion, and 11 - 12° C at 90% immersion. The effect of the 35° inclination angle of the battery pack showed a slightly higher temperature distribution than the 15° one at the low immersed battery’s wall. However, the pitching and rolling conditions gave the battery pack a uniform temperature distribution.