Modeling and experimental validation of parametric changes on the polarization characteristics of solid oxide fuel cells

Studies are presented on solid oxide fuel cells (SOFC) involving theoretical modeling, experimental validation, and design application. The motivation for this study is developing SOFCs for use in unmanned undersea vehicles. SOFCs offer an efficient, fuel flexible, and high energy density power source for this application. A mass transfer model employing the mean transport pore model is developed and validated for use in modeling gas transport in SOFC electrodes. Methodology for extending the detail of this model to higher level models is also illustrated. A full 1-D SOFC numerical single cell simulation is then developed. It is used to investigate the use of cell microstructure grading for improving the mass transfer polarization of SOFC electrodes. It is concluded that increased performance is seen for an anode with what amounts to increased porosity near the anode/electrolyte interface under certain fuel inlet conditions. The full cell model is then validated with experiments that allowed the measurement of specific cell parameters and showed good validation for both temperature variation and hydrogen concentration in the fuel variation.