A novel phase change based cooling system for prismatic lithium ion batteries

The thermal management of lithium ion battery packs in hybrid and plug in electric vehicles is important, especially during high power charging and discharging processes. To maintain the working temperature of lithium ion batteries in hybrid electric vehicles, a novel boiling heat transfer based thermal management system is proposed and its performance is analyzed and measured in terms of the temperature characteristics of the batteries in the pack. The thermal characteristics of the battery pack are presented in terms of the maximum temperature and the temperature uniformity in the pack. The proposed system uses the fuel, which is propane in the proposed model of the hybrid electric vehicle, to cool the batteries and before it is fed to the internal combustion engine of the vehicle. The fuel is the used to generate electrical energy for charging the batteries or driving the vehicle. A one-dimensional electrochemical model and a three-dimensional thermal model are developed to assess the performance of the proposed system under severe discharging and charging cycles. The effects of the propane boiling temperature and the liquid height in the battery pack on the thermal performance of the battery pack are investigated. The present results show that the proposed battery thermal management system is able to maintain the maximum temperature in the battery at under 35 °C and the temperature uniformity to avoid exceeding a temperature difference of 1 °C between the batteries in the pack, for a 600-s cycle of discharging and charging at a rate of 4 C. Increasing the saturation pressure of the propane pool improves the temperature uniformity in each battery, although it overall increases the maximum temperature in the battery.