Thermal Management of Battery Cooling System

Lithium-ion batteries has emerged as the most suitable option to lead the next wave of automotive revolution. Power density, high energy and packing efficiency are main factors for the currently available alternatives. Battery and cell types face issues which need to be worked upon. Battery thermal management is the main factor affecting the working of the battery due to dynamic operation and range of environments under which they operate.The design as well as the three-dimensional computational fluid dynamics (CFD) simulations were carried out for battery system with and without cooling management from single battery to module level and then to pack level. Initially battery system of 40 kWh/360V was designed with 192 Lithium ion pouch cells (48 modules),weight of 325 kg with overall dimensions of 1550x1190x270mm without any coolant system. The analysis resultant temperature distribution is above the optimal performance battery temperature range (35-55℃)with local heat spots. Considering dissipation of surplus heat generated and uniform heat distribution across battery, thermal cooling system was designed and added below the modules. Coolant with 40% ethylene glycol solution in water is used to remove heat from the battery pack. Operational constant power input (heat loss) for the battery system was calculated from three pack chambers as 2880(W) which results in temperature distribution to be cooled. The coolant mass flow rate at the inlet connector is 140g/s with temperature of 25℃. From the digital simulation results, coolant temperature was found to be below 40℃ and battery solid temperatures below 50℃.The pressure drop for the coolant fluid was analyzed and verified for smooth flow paths. The details of the battery cooling system and temperature comparisons with validations are detailed in the paper.