Effects of regulating the cathode gas properties on the ammonia-fueled solid oxide fuel cell. Part II. Experimental and numerical study on the cell power and thermal performance after increasing O2

• Published in: International journal of hydrogen energy 2024-12, Vol.94, p.1329-1343
• Main Authors: Liu, Yimin, Xu, Yishu, Liu, Junjia, Ya, Yuchen, Sun, Boyu, Xiang, Mingyuan, Cheng, Xiaobei
• Format: Article
• Language: English
• Subjects: Ammonia; Cathode gas; Cell performance; DA-SOFC; O2-enriched
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.11.200

This study firstly experimentally determined the performance of direct ammonia solid oxide fuel cell (DA-SOFC) under various O2-enriched cathode gas conditions at 750 °C and 700 °C. Results indicate a significant 40.4% decrease in DA-SOFC power density when temperature dropped from 750 °C to 700 °C, more pronounced than in H2–SOFCs. O2-enriched operation improved DA-SOFC power density, with increases ranging from 7.9% to 22.9% as O2 molar fraction at the cathode inlet rose from 21% to 100% at 750 °C. And at 700 °C, such promoting effect on DA-SOFC was more significant than on H2–SOFC. Interestingly, DA-SOFC open circuit voltage (OCV) showed a nonmonotonic trend with increasing O2 molar fraction, peaking between 30% and 60% O2. Subsequently, multi-physics modeling of DA-SOFC were performed. The numerical results revealed that the observed increase in power density of DA-SOFC in O2-enriched operation mode was primarily resulted from the reduction in concentration polarization, rather than the changed OCVs/Nernst voltages. •Explanations of the factors controlling the enhancement of O2-enriched DA-SOFCs.•Identified and explained the nonlinear trend of OCV with increasing O2.•Confirmed and quantified the impact of O2-enriched operation on DA-SOFCs.