Optimization of solid oxide fuel cell interconnect design

Performance of solid oxide fuel cells (SOFC) is dependent of a set of complex physical and chemical processes occurring simultaneously. Interconnect for SOFC is important as it provides electrical connection between anode of one individual cell to the cathode of neighboring one. It also acts as a physical barrier to protect the air electrode material from the reducing environment of the fuel on the fuel electrode side, and it equally prevents the fuel electrode material from contacting with oxidizing atmosphere of the oxidant electrode side. A three-dimensional numerical model has been developed to evaluate the SOFC including the current collector, rectangular duct gas flow channels, gas diffusion electrodes and electrolyte layer. This model takes into account the hydrodynamic multi-component fluid flow and heat transfer analysis. Numerical results from the developed model using finite element method (COMSOLRTM) show that the predicted polarization curve is in very good agreement with the published data. Simulations were also performed for different interconnect design cases obtained by varying electrode/interconnect contact area using finite volume method (FluentRTM) to investigate the thermal and hydrodynamic behavior and finite element method (COMSOLRTM) to investigate the electrical performance. The optimization is carried out by considering 25% interconnect contact area as the design criteria for maximum temperature gradient limitation. The best interconnect design with 60% interconnect contact area has been chosen which shows good thermal behavior with considerable power output among the different design cases. Simulations show a decreasing power density and reduction of temperature gradient for an increasing contact area. Parametric studies of the fuel cell for different mass flows, hydraulic diameters and interconnect material properties for optimized design have also been performed. Results reveal that the flow rate will have minor impact on the electrical performance compared to the effect of material properties. Strontium doped LaCrO 3 has shown better performance than calcium or magnesium doped LaCrO3. Decreasing the hydraulic diameter improves the mass transport situation along the length of the flow channel.