Cycle analysis of solid oxide fuel cell-gas turbine hybrid systems integrated ethanol steam reformer: Energy management

A solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system that uses such liquid fuels as ethanol is attractive for distributed power generation for applications in remote rural areas or as an auxiliary power unit. The SOFC system includes units that require and generate heat; thus, its energy management is important to improve its efficiency. In this study, a SOFC-GT integrated system with the external steam reforming of ethanol to produce hydrogen for the SOFC is proposed. Two SOFC-GT hybrid systems using a high-temperature heat exchanger and cathode exhaust gas recirculation are considered under isothermal conditions. The effects of key operating parameters, such as pressure, fuel use and turbomachinery efficiency, on the SOFC-GT hybrid system performance are discussed. The simulation results indicate that recycling the cathode exhaust gas from the SOFC-GT system requires less fresh air from the compressor, to maintain the SOFC stack temperature, and the heat recovered from the SOFC system is sufficient to supply both the fuel processor and air pre-heater. In contrast, an external heat is needed for the SOFC-GT system coupled to a recuperative heat exchanger.