(592g) Detailed Steady State Modeling of An Anode-Supported Solid Oxide Fuel Cell (SOFC)

High reactivity, comparatively inexpensive anode and cathode material, high power density, high level of usable heat and the possibility of using flexible fuels have made SOFC an attractive choice for utility and industrial applications. A detailed steady state model of a SOFC can be a useful tool to evaluate the effects of the operating and design parameters and thus can be used to design new cells. The model can also be used for optimization studies of the cell dimensional and operating parameters. In this talk, the development of an optimization-oriented detailed steady state model will be presented.

To attain this goal, a detailed two dimensional dynamic model for an anode-supported tubular SOFC is developed. The model includes: (i) mass and momentum transport phenomena in the anode and cathode gas flow channels for the reactants and the products, (ii) diffusion from the gas flow channels through the porous electrodes to the reaction sites, (iii) activation overpotential through the Butler-Volmer equation with concentration and temperature dependent expression for exchange current density, and (iv) ohmic resistances. The ohmic resistances of the electrodes are modeled by an equivalent circuit model considering the current path length from the current collectors to the TPB. The enhanced area for electrochemical reactions, supported by experimental evidence, is considered by a cylindrical characterization of the TPB interface. For this industrial cell, the cell temperature is maintained by a furnace. However spatial variation in temperature cannot be ruled out. To consider the effects of these variations, energy conservation equations are written. Due to the unknown heat input from the furnace, consideration of the overall energy balance becomes a challenging task. A MAPLE-MATLAB environment is used to solve the steady state model. The computational issues in solving the model will be discussed. The model is validated using data from a commercial SOFC over a wide range of cell temperatures, reactant flow rates, and DC polarizations. Significant observations made during the validation process will also be presented.