3D Modeling of an Anode Supported SOFC Using FEM and LBM

Abstract

Solid oxide fuel cells (SOFCs) are promising as energy producing device, which at this stage of its development will require extensive analysis and benefit from numerical modeling at different time- and length scales. In this study, two models based on finite element method (FEM) and Lattice Boltzmann model (LBM), respectively, are evaluated and compared for an anode-supported SOFC. First, a 3D model is developed based on the FEM, using COMSOL, of a single SOFC operating at an intermediate temperature range. Heat, gas-phase species, momentum, ion and electron transport are implemented and coupled to the kinetics of the electrochemical reactions. Secondly, a 3D model of the porous anode of a SOFC is developed using LBM to investigate the effects of electrochemical reactions on the transport processes at microscale for 3 components (H2, H2O and O2−). Parallel computing in Python is employed through the program Palabos to capture the active microscopic catalytic reaction effects on the heat and mass transport. It is found that LBM can be effectively used at a mesoscale ranging down to a microscale and proven to effectively take care of the interaction between the fluid particles and the walls of the porous media. The 3D LBM model takes into account the transport of oxygen ions within the solid particles of the SOFC anode. Both the oxygen ions and the hydrogen are mainly consumed by the reaction layer. One of the improvements in this study compared to our previous (FEM) models is the captured 3D effects which was not possible in 2D. High current density spots are identified, where the electron transport distance is short and the oxygen concentration is high. The relatively thin cathode results in a significant oxygen mole fraction gradient in the direction normal to the main flow direction.