Design and sensitivity analysis of a multistage solid oxide fuel cell hybrid system with an inter-cooled-recuperated gas turbine and organic Rankine cycle

Abstract

A solid oxide fuel cell (SOFC) hybrid system with an inter-cooled-recuperated gas turbine(ICRGT) and organic Rankine cycle (ORC) was designed to address exergy destruction in the burner of a conventional SOFC and gas turbine (GT) system. In unfired mode of this system, SOFC acts as the GT heater and reheater instead of burners; burners are used only to aid load regulation in fired mode. In unfired mode, the system electrical efficiency is 69.86 % and the overall efficiency is 82.22 %. The total exergy destruction of the system is 21.93 % lower than that in fired mode by exergy analysis, which indicates the effectiveness of reducing afterburner exergy destruction, and the superior energy efficiency of this mode. For the design analysis, we analyzed the influence of different factors on the system, including the number of SOFC modules, turbine outlet temperature, burner exhaust into the turbine, oxidant utilization of SOFC cathode(OUC), and fuel utilization of SOFC anode(FUA) on the system. For the sensitivity analysis, we determined the variation rules of the components and system parameters for fuel proportions of 70–105 %. This work provides a reference for optimizing the design and operation of SOFC-GT and other SOFC hybrid systems.