Cooling of a lithium ion battery using phase change material with air/dielectric fluid media: A numerical study

This paper proposes a method of cooling lithium ion (Li-ion) batteries using a phase change material RT35 in combination with air or a dielectric fluid media (STO 50). Three-dimensional numerical investigations have been carried out using Ansys Fluent to assess the cooling performance under different rates of discharging (1C, 2C, and 3C) of a 38120P Li-ion battery. Five different cases have been investigated and the relative benefits of the combined phase change material-air/dielectric liquid cooling compared over an air or dielectric cooling alone for the battery. Actual heat generation data available for the battery was made use of and supplied to the source term of the energy equation in the solver. A separate user-defined macro on the heat generation of the battery was developed by the authors for the purpose. The numerical simulation was validated comparing the present results with published experimental data for a bare adiabatic 38120P Li-ion cell. The results showed that the cooling was better with phase change material-air or phase change material-dielectric liquid combination compared to air or dielectric fluid alone, capable of reducing the cell temperature further by 6 celcius. From the study, employing phase change material in combination with a dielectric liquid has been suggested as a promising option for thermal management of Li-ion batteries at higher discharging rates to maintain the cell temperatures below 37 celcius.