Effects of Flow Channel Arrangement and Electrolyte Thickness on Thermal Stress for Planar Solid Oxide Fuel Cell Stacks

Typical operating temperature for solid oxide fuel cells (SOFC) is between 700~800°C. A large temperature gradient and thermal stress caused by internal losses and electrochemical reactions may cause SOFC stack performance degradation and even structural damage, which has become a hindrance to its applications. In this study, a three-dimensional multiphysics CFD (computational fluid dynamics) model is developed and applied for a planar SOFC stack to study the temperature and thermal stress distribution, as well as effects of structure and design parameters, including the flow channel arrangement (e.g., co- and count-flow) and thickness of the electrolyte layer. The stack is composed of three-unit cells, metallic interconnect layers, sealing and anode/cathode current collectors. The simulation results reveal that the temperature difference in the counter-flow mode is smaller and the thermal stress is lower than those in the co-flow mode. The overall performance of the stack is better when the electrolyte layer thickness becomes smaller, but the stack temperature and the temperature gradient become higher. In addition, a large temperature gradient due to the thin electrolyte layer leads to a significant increase of the thermal stress in the electrolyte. The findings and research method from this study can be applied to optimize the design of the stack structures, by consideration of the maximum thermal stress and its distribution. Acknowledgements This work is supported by the National Key Research and Development Project of China (2018YFB1502204), the Ningbo major special projects of the Plan “Science and Technology Innovation 2025” (2018B10048). References 1. M. Peksen, Progress in Energy and Combustion Science, 2015; 48: 1-20. 2. K. Eichhorn Colombo, V. Kharton, F. Berto, et al., Computers and Chemical Engineering,2020; 140: 106972. 3. P. Pianko-Oprych, T. Zinko, et al., Journal of Power Sources, 2015; 300: 10-23. 4. J. Robinson, L. Brown, R. Jervis, et al., Journal of Power Sources, 2015; 288: 473-481. 5. L. Chang, H. Liu, Y. Shiu, et. al., Journal of Power Sources, 2010; 195: 1895-1904. 6. A. Selimovic, M. Kemm, T. Torison, et. al., Journal of Power Sources, 2005; 145: 463-469. 7. M. Xu, T. Li, M. Yang, et. al., Science Bulletin, 2016; 61: 1333-1336. 8. C. Lin, L. Huang, L. Chiang, Y. Chyou, Journal of Power Sources, 2009; 192: 515-524. 9. M. Peksen, International Journal of Hydrogen Energy, 2013; 38: 553-561. 10. X. Fang, Z. Lin, Applied Energy, 2018; 229: 63-68. 11. D. Cui, M. Cheng, Journal of Power Sources, 2009; 192: 400-407. 12. Q. Li, Z. Xu, M. Cheng, et al., Modern Physics Letters B, 2020; 34(15): 23. 13. W. Zhang, D. Yan, J. Duan, et al. International Journal of Hydrogen Energy, 2013, 38(35): 15371-15378. 14. Y. Zhang, W. Jiang, S. Tu, et al., International Journal of Hydrogen Energy, 2018, 43(9): 4492-4504. Figure 1