Efficiency analyses of solid oxide fuel cell power plant systems

In this paper, the effects of fuel utilization, air-to-fuel ratio (A/F) and pre-reforming rate on the plant efficiency, including heat and electric efficiencies, of sequential-type and fully recuperative-type of solid oxide fuel cell (SOFC) power plant are studied with the GCTool software developed by American Argonne National Laboratory (ANL). Methane is chosen as fuel, air as oxidant, and the pressure drop due to stream transported in the duct and components is considered in both types of power plant systems. A full analysis of the state at each node of the system is conducted. The results reveal that the A/F factor is the most important factor on system efficiency, and the pre-reforming rate of fuel is insignificant to the efficiency, but it can be used as an auxiliary tuner for the operating temperature of the solid oxide fuel cells in addition to A/F value. Under the same settings, overall plant efficiency is higher in the sequential type than in the fully recuperative type of SOFC power plants. On the other hand, for electric efficiency, the opposite trend is observed.