Multiscale modeling of solid oxide fuel cells: Accounting for oxidation and reduction electrochemical reactions at the electrode microstructure level

An important limitation of a macroscale Solid Oxide Fuel Cell (SOFC) model is that it needs to be calibrated with experimental data obtained from a test rig that has the same microscale features as the model. Hence, there is no apparent way to use a validated macroscale model to study the effect of microscale features on the performance of a full SOFC unit. To address this limitation, we introduce a multiscale modelling approach for Solid Oxide Fuel Cells (SOFCs) that captures how macroscopic and microstructural features interact. It accounts for both oxidation and reduction reactions at the anode and cathode sides of the cell at the pore-scale and models the polarization curve of the entire SOFC unit. This work employs a novel multiscale framework which allows macroscopic predictions to be made by directly incorporating not only macroscale but also microscale features of a SOFC unit. Our multiscale framework integrates the solution of multiple spatially distributed microscale “patches” (consisting of porous electrodes and the electrolyte) along the length of the cell, with a macroscale solution of the rest of the entire SOFC unit, in an iterative fashion. The method is first validated through a case study, used to investigate the influence of the number of microscale patches on model accuracy and performance. It was found that the use of ten spatial patches provides an optimal balance between computational effort and accuracy for the tested configuration. The proposed multiscale framework enables the evaluation of novel SOFC designs, where both macro- and microscale features are considered.