Compactness analysis of PCM-based cooling systems for lithium battery-operated vehicles

Demand for sustainable transport system is craving for hybrid and electric vehicles with high-power and high-energy electric storage system for increased range of haul. To support such high-power applications, the Li-Ion battery developers’ trends are to formulate batteries with high discharge rate and high ampere rate of up to 100 Ah. Those batteries would suffer from a drastic increase in heat generation rate, which could increase the temperature of the battery above 313 K (40 °C) under the conventional cooling system. Most of the research works proposed direct liquid cooling or liquid cooling plates to attain sufficient cooling for high ampere battery packs. In the present research, the focus is on a hybrid cooling system that is more versatile in providing a flexible cooling mechanism with various design parameters to control the cooling performance for the battery pack. Through computational fluid dynamics simulations, it is understood that it needs 9 mm thickness for pure phase change material (PCM) cooling system to control the temperature within 313 K (40 °C) for the battery with heat generation rate of 30,046 W/m³. The proposed hybrid cooling system can control the temperature within 313 K (40 °C) for battery with heat generation rate of 120,183 W/m³ applying 6 mm thickness of PCM, thus reducing the overall size of the cooling system by 16.3%. It is also predicted that the hybrid cooling system can further improve its performance by increasing the coolant flow rate beyond 2 L/min. Under the 0.5C discharge condition, hybrid cooling can be manageable with zero pumping losses.