Off-design performance analysis for an integrated system of solid oxide fuel cell and supercritical carbon dioxide Brayton cycle with CO2 capture

Abstract

Solid oxide fuel cell (SOFC) and supercritical carbon dioxide (sCO2) Brayton cycle are both clean and efficient technologies for energy supply. The present study proposes an innovative SOFC-based system combined with sCO2 Brayton cycle and CO2 capture system. The bottoming sCO2 cycle can improve efficiency of the integrated system by recovering waste heat from the combustion chamber while using oxy-fuel combustor to achieve low-energy CO2 capture. And the quasi-steady model of the system is developed to evaluate the system design and off-design performances. The simulated results indicate that the net electrical efficiency and reducing CO2 emission of the system are 60.96% and 0.342 kg/kWh, respectively. The system parametric analysis indicates that the reasonable recirculation ratio, fuel utilization and fuel flow rate are prerequisites for the safe and efficient operation of the integrated system. Based on the analysis, a system control strategy is proposed to satisfy the demand for wide-range load adjustment (30%-100%), while the efficiency of the integrated system is decreased from 60.96% to 50.33% during the load reduction process.