Electric Vehicle Battery Cooling via Loop Heat Pipes coupled with Underbody Aerodynamics

This paper presents a feasibility study on a fully passive cooling system for electric vehicles using Loop Heat Pipes (LHP) to transfer the batteries excess heat to the underbody of the vehicle. Multiple LHPs are in contact with a battery module, on the evaporator side, while their condensers are embedded in the underbody of the vehicle, cooled via aerodynamic cooling. The study is conducted numerically, by means of a previously validated transient 1-D Lumped Parameter Model (LPM) able to simulate the thermos-fluidic behavior of the LHP, and aerodynamic CFD simulations coupled with heat transfer. The CFD results provide the convection heat transfer coefficient at the condenser wall, which is inputted into the 1-D LPM to design the condenser in order to achieve successful operation of the cooling system, and to evaluate the temperature evolution of the cells. The performance of the proposed cooling system was evaluated over 1C, 2C, 3C charging cycles followed by a 30 minutes 1C driving section. The proposed cooling system was able to contain the cell temperature inside the acceptable limits, even at challenging conditions such as 3C charging, with maximum temperature being 51.6 °C for 3C, 39.3 °C for 2C and 27.5 °C for 1C. All without using any additional energy.