Solid Oxide Fuel Cell Material Structure Grading in the Direction Normal to the Electrode/Electrolyte Interface Using COMSOL Multiphysics®
Fuel cells (FCs) are promising as an energy producing device, which at this stage of development will require extensive analysis and benefit from numerical modeling at different time- and length scales. COMSOL Multiphysics® is used to describe an intermediate temperature solid oxide fuel cell (SOFC). Governing equations for heat, gas-phase species, electron, ion and momentum transport are implemented and coupled to kinetics describing electrochemical as well as internal reforming reactions. It is found, from the parameter study, that grading the electron tortuosity (decreased under the fuel and air channels), the electron conducting material fraction (increased under the fuel and air channels) and the pore tortuosity (decreased under the interconnect ribs), in the direction normal to the electrode/electrolyte interface increases the performance (average ion current density) slightly. On the other hand, is the performance slightly decreased from grading the porosity (increased under the interconnect ribs).