Coupling impacts of SOFC operating temperature and fuel utilization on system net efficiency in natural gas hybrid SOFC/GT system

Abstract

The major design parameters of SOFC have great impacts on the net electrical efficiency of SOFC/GT hybrid systems. The influence of the SOFC operating temperature and fuel utilization on the net efficiency of a pressurized solid oxide fuel cell gas turbine hybrid system was studied in this paper. The system model was combined a 1D SOFC model, which included a lumped equilibrium steam methane reformer model in the Simulink, with a gas turbine recuperated cycle model in Ebsilon®. A system design point study was established to observe the coupling impacts of SOFC operating temperature and fuel utilization on the system performance. Thirty design cases of SOFC operating temperatures (635 °C–835 °C) over a range of SOFC fuel utilization(45%–90%) were evaluated. The optimal SOFC fuel utilization shifted from 65% to 55% when the SOFC operating temperature decreased from 835 °C to 635 °C. The maximal(minimal) system efficiency was 74%(49%) at 65%(90%) SOFC fuel utilization with operating SOFC at 835 °C(635 °C). The results show that high operating temperature leads to the high efficiency of the entire hybrid system, but high fuel utilization might cause a decrease in system efficiency.

Keywords

• Solid oxide fuel cell
• Gas turbine
• Hybrid system
• Operating temperature
• Fuel utilization
• System performance analysis