IMPEDANCE MEASUREMENT AND SIMULATION ON A DISC-TYPE SOFC UNDER POWER GENERATION

摘要

AC impedance characteristics under practical loading conditions were numerically calculated and the measurements under DC current conditions were carried out using actual size planar disc-type solid oxide fuel cells (SOFCs) employing doped lanthanum gallate as a solid electrolyte. Under the conditions of relatively high fuel utilization, the change in composition of the gases caused by the electrochemical fuel cell reaction leads to the appearance of gas conversion impedance, and considerable variation exists in Nernst potential and current density along the gas flow axis. A semi-circular behavior that can be represented by an RC parallel circuit was also predicted by the simulation. Dependency of R and C on fuel utilization was calculated, and experimentally measured behavior was compared with the simulated results and discussed.