Composite Thermal Control Systems with Phase Change Material in Metal Foam for Lithium Batteries Cooling.

Electric cars, in addition to representing an ecological solution, represent a turning point in terms of renewal for the world economy. One of the main problems of electric cars is given by the thermal control of their batteries, as below and above a certain temperature range, they abruptly decrease the range of the vehicle, creating inconvenience to the owners of such cars. The thermal control of lithium batteries for electric cars must therefore take into account both the problems of thermal increase due to the operation of the battery itself, and the climatic conditions outside the vehicle that impact, if above a certain range, negatively on the performance of the car, decreasing both the range and the life of the battery. In this study, an attempt is made to control the temperature peaks due to the operation of the battery itself to this end, a thermal control system with metal foam phase change material is studied in order to evaluate the heat transfer behavior for use in the cooling of lithium batteries. A two-dimensional model is considered to numerically study the thermal control with different charge and discharge cycles. The battery is simulated as a wall-mounted heat flow. Thermal control is achieved by means of an inner layer of copper foam and phase change material, PCM (paraffin) and the outer surfaces are cooled by convective flow. The governing equations, written assuming local thermal equilibrium for the metal foam, are solved by the finite volume method using the commercial Ansys-Fluent code. Several cases are simulated for different values of external convective heat transfer coefficient. Results, performed for metal foams with different PPIs and porosities, are provided in terms of temperature fields and liquid fraction, heat transfer behaviors such as surface temperature profiles as a function of time, and temperature distributions along the outer surface of the battery for the different cases. In addition, some comparisons with pure PCM within the thermal control system are provided to show the advantages of the composite thermal control system with PCM within the metal foam. The results obtained show that the best solution among those studied is given by the use of copper foams filled with paraffin PCM. [ABSTRACT FROM AUTHOR]