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

Abstract

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 (Ptotal and Etotal) 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 Ptotal, Etotal and ηtotal 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.