Performance analysis of the Inverted Brayton Cycle in the atmospheric solid oxide fuel cell hybrid power system

Enhancing the energy conversion efficiency of Solid Oxide Fuel Cells (SOFCs) hinges significantly on maximizing the recovery efficiency of high-temperature waste heat. The Inverted Brayton Cycle (IBC) emerges as a promising candidate for integration with ambient pressure SOFCs, thanks to its compatibility with atmospheric expansion dynamics. This study endeavors to model the Solid Oxide Fuel Cell-Inverted Brayton Cycle (SOFC-IBC) hybrid system, delving into the factors influencing IBC performance. Through meticulous simulation and analysis, we investigate the impacts of pressure ratio, minimum cycle temperature, and steam injection flow rate on system behavior. Additionally, we conduct a comprehensive examination of exergy destruction and efficiency implications. Our findings reveal a substantial enhancement in the IBC system's performance through pressure ratio incrementation or minimum cycle temperature reduction. Conversely, the steam injection flow rate exhibits divergent effects across different operational regions. The SOFC-IBC hybrid system demonstrates a remarkable potential to elevate SOFC exergy and thermal efficiency by 5.68 % and 11.68 %, respectively, thereby yielding a notable output power increase of 39.55 kW. Furthermore, optimizing pressure ratio or curbing steam injection flow rate proves beneficial for enhancing exergy efficiency. Crucially, the integration of the SOFC-IBC hybrid system offers a solution to the challenge posed by the pressure mismatch, which hinders the direct coupling of the gas turbine with the atmospheric SOFC. These insights underscore the applicability of IBC in atmospheric SOFC energy recovery systems, suggesting promising prospects for widespread adoption in energy optimization initiatives.