A Two-Dimensional Modeling Study of a Planar SOFC Using Actual Cell Testing Geometry and Operating Conditions

Abstract

This paper reports a new electrochemical performance study performed on a planar SOFC cell. This study consists of a 2D model developed using a commercial software, namely Comsol Multiphysics. The model includes fluid dynamics, electrochemistry, electrical conduction, and diffusion physics. This model was built using the actual button cell testing geometry and using experimental data for validation purposes. The objective of this study is to understand the effects of the testing setup used on the cell performance and to recommend an improved design or geometry where the cell performance is independent of any flow maldistribution in both the air and fuel side of the SOFC cell. The air and fuel flow rates are studied to determine the effects on the cell performance. The effects of electrode porosities are studied together with the fuel and air flow rates. The distance from the SOFC cell to the discharge fuel feed tube and air chamber geometry are studied as well. The modeling results indicate that the SOFC electrochemical performance becomes independent of any flow maldistribution at relatively high flow rates for both fuel and air. Reduced electrode porosities play a role in the cell performance, and larger flow rates are required in order to achieve a cell performance independent of flow rates. The cell performance is also affected by the distance from the SOFC cell to the fuel discharge tube and the air chamber geometry. The behavior seen in the cell performance can be explained by a non-uniform mole fraction of reactants near the electrode surface.