Performance analysis and multi-objective optimization for a hybrid system based on solid oxide fuel cell and supercritical CO₂ Brayton cycle with energetic and ecological objective approaches

In this paper, an elaborate investigation for a hybrid system based on solid oxide fuel cell (SOFC) and supercritical CO₂ (SCO₂) Brayton cycle is implemented to enrich the performance design details. First, the hybrid system general performance characteristic is revealed and the power improvement rate comparison between the hybrid system and other typical SOFC-based hybrid systems is presented. Then, the combined effects of current density and six critical parameters are evaluated to show the interaction between the SOFC and SCO₂ cycle. Based on above, the parameter sensitivity analysis is conducted and a comprehensive optimization considering both energetic and ecological performance is performed. The results show that the maximum total power output and ecological objective function of the hybrid system (P_total and E_total) are respectively improved by 43.72 % and 45.70 % compared with those of an individual SOFC. The final decision of the multi-objective optimization is that P_total, E_total and η_total are 2345.68 kW, 2014.52 kW and 64.35 %, respectively. This paper offers an effective parameter optimization strategy for the hybrid system based on the coupling mechanism study of the SOFC and SCO₂ cycle, and hints the broad prospect of waste heat recovery for high-temperature fuel cells via SCO₂ cycles.