Mathematical modeling of planar solid oxide fuel cells

Abstract

A mathematical model predicting the performance of planar solid oxide fuel cell (SOFC) has been developed. The model is fuel flexible, which implies not only pure H 2 but also any reformate composition (H 2, H 2O, CO, CO 2 and CH 4) can be used as a fuel. The important characteristic of this model is the consideration of reaction zone layers as finite volumes. Reaction zone layers are thin layers in the vicinity of the electrolyte where electrochemical reactions takes place to produce electrons, oxide ions and water vapor (and/or carbon dioxide). In addition, the effect of Knudsen diffusion is accounted in the porous electrode (backing) and reaction zone layers. The model can predict the performance of SOFC at various operating and design conditions. The predicted performance of SOFC is validated with the measured data found in the literature. An excellent agreement is obtained between the predicted performance and the experimental results. Moreover, the effect of various operating and design parameters on the performance of SOFC has been examined. It is found that the anode concentration overpotential in an anode-supported SOFC is about four orders of magnitude smaller than the anode ohmic overpotential even at higher current densities. Further, it is found that the single largest contributor to the total cell potential loss is ohmic overpotential and hence it needs to be minimized to enhance the cell performance.