Thermodynamic sensitivity analysis of hybrid system based on solid oxide fuel cell

Abstract

This paper is focused on the steady-state performance of a hybrid solid oxide fuel cell (SOFC)-gas turbine (GT) cycle. First, the model of the hybrid SOFC-GT cycle is developed and then the model is used to perform a series of sensitivity analyses to investigate the impact of various design and operating parameters on the performance of the cycle without anode recirculation when the system is fuelled with methane. The following system operating and design parameters are investigated: SOFC operating temperature, fuel utilization factor, current density; system operating pressure; turbine inlet temperature (TIT); and isentropic efficiency of the GT. The system performance is monitored by recording and evaluating the specific work of the SOFC, GT, and system as a whole; SOFC-to-GT work ratio; and cycle efficiency (based on the LHV). The results of the modeling illustrated that the cycle efficiency can be improved by increasing system operating pressure, SOFC operating temperature, and GT isentropic efficiency and decreasing SOFC current density and TIT. Also, it is shown that increasing system operating pressure, fuel utilization factor, and TIT can positively affect cycle net specific work, while increasing SOFC operating temperature and SOFC current density has negative impact on the cycle net specific work. The influence of the fuel utilization factor on the cycle efficiency depends on the GT isentropic efficiency.