Strongly coupled electrochemical-thermal-fluid models of a battery pack using FEniCS

Electric vehicles represent a promising departure from conventional fuel-powered vehicles, with battery packs assuming a pivotal role in their design and performance. However, these battery packs, particularly those equipped with active cooling systems, present intricate multiphysics systems encompassing fluid dynamics, electrochemistry, and heat transfer.

In our study, we propose a novel workflow for modeling battery packs, employing FEniCSx to simulate coolant flow and heat transfer within the battery pack. The fluid dynamics within the cooling channels is described by the steady-state Stokes flow under the assumption of incompressible creeping flow. The heat transfer is governed by the steady-state convection-diffusion equation, with the convective velocity derived from the Stokes equations, assuming weak coupling between the two problems.

The electrochemical and thermal responses of the batteries are modeled using the Doyle-Fuller-Newman model, a high-fidelity physics-based model implemented with the open-source battery simulation package PyBaMM. The battery response is strongly linked to the temperature within the battery pack, as electrochemical reactions are temperature-dependent and impact the heat generated by the batteries. To manage this coupling, we employ openMDAO with a fixed-point iteration algorithm.

Our research explores three distinct battery pack configurations, each with variations in fluid inlet and outlet placements. For each configuration, we analyze crucial parameters such as maximum temperature, temperature distribution, temperature gradient, pressure drop, and fluid velocity to comprehensively understand battery pack performance. The batteries’ discharge rate is set as a potential electric aircraft flight, illustrating the practical implications of the battery pack’s performance in real-world applications.