Analyzing different planar biogas-fueled SOFC stack designs and their effects on the flow uniformity

Abstract In this analysis, a 3D mechanistic model is developed for two different stack designs consist of five planar solid-oxide fuel cells fueled with biogas. Stack flow uniformity index criteria are employed to investigate the flow characteristics. The Detailed transport processes and chemical/electrochemical reactions with overpotential losses are also employed to evaluate the effects of the flow uniformity on the performance of the stacks. The model is validated by comparing the simulated results with the experimental data. Comparison of species, temperature, and current density distribution along with the normalized mass flow rate for two different designs are conducted. The results revealed that the uniformity indexes for the stack design with rectangular strips separators exceed 0.98, whereas for the other design with circular guiding vane separators, are approximately 0.88. Despite the higher flow uniformity of the rectangular separator design, temperature and current density distributions are found to be more uniform with the circular guiding vane separators. An error analysis is also conducted to establish the accuracy of the model. The error analysis demonstrated that the mean relative error (MRE) and root mean square error (RMSE) indexes (%) are 1.7157 and 7.7921 for 120×120 mm2, and 1.5147 and 6.89 for 100×100 mm2, respectively.