Numerical performance analysis of solid oxide fuel cell stacks with internal ammonia cracking

• Published in: International journal of hydrogen energy Vol. 48; no. 91; pp. 35723 - 35743
• Main Authors: Rizvandi, Omid Babaie, Nemati, Arash, Nami, Hossein, Hendriksen, Peter Vang, Frandsen, Henrik Lund
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.11.2023
• Subjects: Ammonia cooling effects; Ammonia-fueled operation; High-temperature gradient; Solid oxide fuel cell stack; Stack-scale modeling; Thermal stresses; Ammonia cooling effects; Stack-scale modeling; Solid oxide fuel cell stack; High-temperature gradient; Ammonia-fueled operation; Thermal stresses
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2023.05.321

Ammonia-fueled operation of solid oxide fuel cells is a promising alternative to their hydrogen-fueled operation. However, high ammonia decomposition rates at elevated operating temperatures of the solid oxide cells lead to a significant temperature drop at the stack inlet, causing increased thermal stresses. A multi-scale model is used in this study to investigate stack performance under direct feed and external pre-cracking of ammonia. Additionally, the effects of co- and counter-flow configurations, gas inflow temperatures, current density, and air flow rate on the stack performance under direct ammonia feed are examined. The simulation results show that for gas inlet temperatures above 750 °C, the power densities with direct feed and external cracking of ammonia differ by less than 5%. Moreover, it is indicated that the thermal stresses are lowest for the co-flow case, which decrease with decreasing gas inlet temperature and current density and with increasing air flow. Finally, this study shows that under practically applicable operating conditions, the risk of mechanical failure of the cells under direct ammonia feed operation is small. •Ammonia cools down the stack but leads to high tensile stresses.•Stack performs closely under direct and pre-reformed ammonia at higher temperatures.•Counter-flow configuration and higher inflow temperatures increase tensile stresses.•Lower load current density and higher air mass flow rate decrease tensile stresses.•Mechanical failure is not expected for operating condition considered in this study.