Heat and mass transfer modeling and assessment of a new battery cooling system

A novel refrigerant based battery thermal management system for electric vehicles is proposed, modeled, simulated and analyzed. The system is modeled and simulated with a one-dimensional electrochemical model integrated with a three dimensional heat and mass transfer model. The proposed battery cooling system uses phase change through boiling to cool the batteries. Refrigerant R134a is the phase change fluid in the proposed system, which changes phase by absorbing the heat generated by the batteries in a battery pack. The R134a liquid partially fills the battery pack forming a pool, in which the batteries are partially submerged. When the liquid refrigerant absorbs part of the heat generated by the batteries, it evaporates forming R134a vapor. The R134a vapor cools the surface of the battery that is not covered by the liquid R134a. Then the superheated R134a vapor exits the pack and enters a return channel. The return channel with the help of the car air conditioning system condenses the R134a vapor back to a liquid. The R134a condensate is returned to the R134a tank to be used again in cooling the batteries. The performance of the proposed battery cooling system is assessed for a 600 s charging and discharging cycle at a rate of 5C and for 10 min of an Artemis motorway drive cycle. The results show that better performance is obtained through the use of a refrigerant based thermal management system compared to air and liquid based cooling systems, in terms of maximum battery temperature and temperature difference between the batteries in the pack.