Solution of inverse thermal problem for assessment of thermal parameters of engineered H2 storage materials

Abstract

New materials for hydrogen storage applications require accurate thermal parameters for the design of the thermal management system. The task of material characterization has been formulated as an inverse thermal problem of parameter estimation from thermal conductivity measurements in orthogonal directions. The three-dimensional (3D) forward problem that models the transient thermal conductivity measurement experiment has been implemented in COMSOL®. The backward problem has been solved using the MATLAB®’s Global Optimization Toolbox™, augmented with an original acceleration strategy that is based on a smooth parametric reconstruction of the objective function manifold. The error in the parameter estimates is dominated by the inaccuracy of the physical forward problem, with the statistical variation of the measurements playing a secondary role. The traditional method of linear error estimation based on the computation of a sensitivity matrix in the vicinity of the optimal solution has been shown to overestimate the errors in the parameter estimates due to the low values of the sensitivity matrix norm in the vicinity of the optimal solution. The error was therefore re-estimated from the reconstruction of the objective function manifold close to the optimal parameter values.