Efficiency analysis of a hydrogen-fueled solid oxide fuel cell system with anode off-gas recirculation

This study analyzes different hydrogen-fueled solid oxide fuel cell (SOFC) system layouts. It begins with a simple system layout without any anode off-gas recirculation, continues with a configuration equipped with off-gas recirculation, including steam condensation and then considers a layout with a dead-end anode off-gas loop. Operational parameters such as stack fuel utilization, as well as the recirculation rate, are modified, with the aim of achieving the highest efficiency values. Drawing on experiments and the accumulated experience of the SOFC group at the Forschungszentrum Jülich, a set of operational parameters were defined and applied to the simulations. It was found that anode off-gas recirculation, including steam condensation, improves electrical efficiency by up to 11.9 percentage-points compared to a layout without recirculation of the same stack fuel utilization. A system layout with a dead-end anode off-gas loop was also found to be capable of reaching electrical efficiencies of more than 61%.