Simulation of SOFC stack and repeat elements including interconnect degradation and anode reoxidation risk
Reliability of SOFC stacks is a complex and key issue. This paper presents a simulation study including some degradation processes, namely, interconnect degradation and the anode reoxidation potential. Quantification for these phenomena has been included in a repeat element model to simulate stack degradation and study the influence of design and operating parameters on the degradation. Interconnect degradation is based on Wagner’s law for oxide scale growth, parameters applying to metallic interconnects used in planar SOFCs are used. Anode re-oxidation is modeled by thermodynamic equilibrium which allows identification of the operating conditions where the anode is likely to be re-oxidized. Simulations have been carried out for a large number of cases at different current density, fuel utilization and temperature, for 2 different stack designs (base-case and modified design). Using an appropriate criterion to express degradation, all these cases point to a clear trade-off between interconnect degradation and local temperature. The base case design is likely to be exposed to anode reoxidation.