Modeling and analysis of the multiphysics transport parameters of a kilowatt-class multistack module of reversible solid oxide cells

Degradation and reliability-related issues are major obstacles in the large-scale commercialization of multistack modules of reversible solid oxide cells. Understanding various transport processes, the distributions of multiphysics parameters, and chemical/electrochemical reactions is critical for improving the performance and reliability of modules. In the present study, a simplified method based on the distributed resistance analogy approach was developed for constructing a three-dimensional model of a kilowatt-class multistack module comprising reversible solid oxide cells. The uniformity of the parameter distribution and the fuel gas conversion rate were predicted, and the effects of the number of stacks, number of cells, cascade configuration, and module scale were investigated under dual-mode operation. The uniformity factor of the gas flow ranges from 0.152 to 0.817 in modules of different sizes and configurations; this range is considerably greater than the uniformity factors of the other transport parameters under dual-mode operation. The uniformity factors of flow, temperature, and current density are 17.7%–78.1% lower under parallel stack configurations than under series stack configurations. Doubling the number of cells resulted in the flow uniformity factor increasing by 108%–212%, and doubling the active area of the cells resulted in the uniformity factors of the temperature and current density increasing by 107%–135%. High reactant conversion rates and low nonuniformity factors are achieved for parallel multistack modules with a power of 8–32 kW, which is appropriate for large-scale applications.