Design and development of liquid immersion cooling system of high-performance light electric vehicles

The reliance on fossil fuels in the automotive industry has driven the need for efficient and sustainable solutions, particularly in electric vehicles (EVs). Lithium-ion batteries, preferred for their high energy density, require effective Battery Thermal Management Systems (BTMS) to ensure safety and performance. This study investigates the design and development of a liquid immersion cooling system for a 48 V, 18.2 Ah Lithium Nickel Manganese Cobalt Oxide (NMC21700) battery pack designed with 13 × 4 cells (13S4P). Using M&I's MIVOLT DFK dielectric fluid, both numerical simulations and experimental analyses were conducted to evaluate heat generation, temperature rise, and cooling efficiency under various conditions. The results are also compared with simulations performed. The immersion cooling significantly reduces battery temperatures compared to forced air cooling. In liquid immersion cooling, the battery reaches a maximum temperature of 48 °C at a fluid velocity of 0.2 m/s during 2C charging–discharging, whereas under similar conditions with forced air cooling at 10 m/s the maximum temperature rises to 60 °C. Parasitic power consumption for immersion cooling is as low as ∼2% of battery capacity at 3C, and the deviation between simulation and experimental results is only 2.17%, demonstrating the system effectiveness and model accuracy of liquid immersion cooling under different dynamic and static conditions for high-performance battery applications.