SOFC Cell Design Optimization Using the Finite Element Method Based CFD Approach

Fuel cells are hopeful for future energy systems, because they are energy efficient and able to use renewable fuels. A coupled computational fluid dynamics approach based on the finite element method, in three-dimensions, is used to illustrate a planar intermediate-temperature solid oxide fuel cell. Governing equations for momentum, gas-phase species, heat, electron and ion transport are implemented and coupled to kinetics describing electrochemical reactions. Three different cell designs are compared in a parametric study. The importance of the cathode support layer is revealed, because this layer significantly decreases the oxygen gas-phase resistance within the cathode (at positions under the interconnect ribs) in the direction normal to the cathode/electrolyte interface as well as the electron resistance inside the cathode (at positions under the air channel) in the same direction. It is concluded that wider and thinner gas channels enable a more compact design with only a slightly decreased cell current density (per cross-sectional electrode/electrolyte interface area), i.e. a considerably increased volumetric cell current can be achieved.