Computational and experimental investigations on liquid-based battery thermal management systems for electric vehicle applications under various discharge rates with different flow speeds

Abstract

Batteries are considered the heart of an electric vehicle and they need proper maintenance and monitoring. Batteries while operating at a higher discharge rate elevate the battery module temperature drastically. The high temperature may destroy battery life and cycle. Battery Thermal Management System (BTMS) plays a vital role in sustaining the battery at optimum temperature (25 degrees C to 40 degrees C). In this present work, liquid-based thermal management is adopted to extract heat from battery modules. The main novelty of this work is to reduce the weight density of the battery module by using aluminum for cooling channel fins. Aluminum is less dense (2.7 g/ cm3) compared to copper (8.96 g/cm3), so the overall weight of the system is decreased to around 60 %. The additional advantage is that aluminum channels increase the thermal conductivity of about 239 W/m.K at 20 degrees C. Computational studies are conducted by varying the following parameters such as the flow rate of the coolant by 3 m/s, 4 m/s, and 5 m/s. To increase the cell contact area with the channel the height of the channel is increased to 80 %. Ethylene glycol and water are used as a base coolant and the results obtained are compared and analyzed. Numerical Simulation studies using ANSYS Fluent convey that a flow rate of 3 m/s shows good cooling performance. In the case of coolant, Ethylene glycol shows better cooling performance when compared with water. Further experimental testing is carried out for the above-considered parameters by fabricating the overall coolant flow channel and cell arrangements to verify the numerical result.