Abstract
Krylov-based methods are an attractive alternative to traditional fixed-point iterative schemes, being much more robust and accurate when solving elliptic equations (e.g., the energy equation in the solid domain). This study assesses the performance of a Krylov-based accelerator, when used for Conjugate Heat Transfer (CHT) simulations of an electrical battery-pack. The non-linear nature of CHT simulations (due to spatial & temporal changes in boundary conditions) necessitates the use of the non-linear form of the Krylov-based accelerator (termed NKA). NKA is used while performing steady-state CHT simulations of an air-cooled Lithium-ion battery-pack, specifically to help accelerate the solution of the solid-domain energy equation. The effect of using either isotropic or anisotropic thermal conductivity within the cylindrical Lithium-ion battery cells is also evaluated. Results obtained using the NKA accelerator are compared, in terms of accuracy and speed, to those obtained from a traditional non-linear fixed-point iterative scheme based on Successive Over-Relaxation (SOR). The NKA accelerator is found to perform quite well for the problem at hand, providing results with the specified accuracy, while also being between 5 and 20 times faster than SOR (while solving the solid energy equation). The robust nature of NKA also leads to better global heat-balance within the battery-pack at all times during the simulation. Overall, computational cost reductions of 30% to 40% are observed when using NKA for the battery-pack simulations.
Physics-based prognostics of lithium-ion battery using non-linear least squares with dynamic bounds
