Comparison and optimization of electrochemical and thermal performances of SOFC with different configurations of a metal foam flow field

Abstract

The effects of different configurations of a metal foam flow field on current density and temperature gradient of a single channel solid oxide fuel cell (SOFC) are investigated, and the overall performance of the optimum configuration is optimized. First, model A (conventional channel-rib flow field) is compared with three different configurations (i.e., model B with metal foam flow field only at anode, model C with that only at cathode, and model D at both). Although model C achieves the highest current density, its temperature is also fairly high. Although model B achieves the lowest temperature gradient, its current density is also fairly low. Model D performs well in both current density and temperature gradient. Then, the effect of electrode thickness and metal foam thickness on the performance of model D is investigated. The Ohmic polarization of model D remains almost constant with different electrode thicknesses, and its concentration polarization decreases as the electrode thickness decreases, which is totally different from the channel-rib flow field. Moreover, a thinner cathode causes lower activation overpotential, whereas a thinner anode causes higher activation overpotential. In general, a thick anode, a thin cathode, and thin metal foam can maximize the current density of model D, while a thick electrode and metal foam can always reduce the temperature gradient. Finally, the Taguchi method and gray relational analysis are used to optimize the current density and temperature gradient of model D. The current density of an optimized model is 3.27% higher than that of the original model with a temperature gradient of 9.05 K/cm.