Numerical simulation of a planar heat pipe for thermal management of EV batteries

Abstract

As electric vehicles advance toward higher energy density and faster charging, battery heat generation continues to increase. This places higher requirements on both heat dissipation capacity and temperature uniformity in battery thermal management systems. In this thesis, a three-dimensional transient computational fluid dynamics (CFD) model is developed in ANSYS Workbench and Fluent to study the thermal response of a planar heat pipe for electric vehicle battery cooling. The volume of fluid (VOF) model and the Lee evaporation-condensation model are used to describe the water-vapor phase-change process, while the metal mesh is modelled as a porous medium.

The effects of filling ratio, heat-source layout, and cyclic heat-load profile are analysed in this thesis. The results show that the filling ratio strongly affects the internal liquid distribution and the external temperature response. The heat-source layout changes both the hot-spot location and the temperature distribution. The dispersed layout gives a more balanced response between heat transfer and temperature uniformity. Under cyclic heat loads, the planar heat pipe shows a repeatable thermal response after the initial transient stage, without a continuous increase in temperature. Overall, the results indicate that the planar heat pipe has potential for passive battery thermal management under non-uniform heat sources and time-varying heat loads.