International Journal of Energy Research, Vol.45, No.3, 3801-3820, 2021
Conceptual design and performance analysis of a novelCHPsystem integrated with solid oxide fuel cell and supercriticalCO(2)partial preheating cycle
The paper proposes a novel combined heating and power (CHP) system integrated with solid oxide fuel cell (SOFC) and supercritical CO2(SCO2) partial preheating cycle to improve the energy utilization rate by employing the SCO(2)cycle to recover the waste heat from the SOFC. The SCO(2)partial preheating cycle can not only improve the net output power but also preheat the air supplied to the SOFC for enhancing the system efficiency. Sensitivity analysis is implemented to study the influences of six key parameters (ie, fuel flow rate, excess air ratio, fuel utilization factor, CO(2)turbine inlet temperature, CO(2)compressor pressure ratio, and CO(2)split ratio) on the proposed system in terms of thermodynamic behaviors. And then the optimal operating conditions for the different objectives are determined by parametric optimization. The results indicate that the optimal overall electrical efficiency and CHP efficiency of the proposed system are 72.84% and 83.83% respectively, while the exergy efficiency can achieve 70.84%. Furthermore, the best trade-off result is obtained with the energy output of 434.71 kW and the exergy efficiency of 64.28%. Finally, the investigation demonstrates the fuel flow rate is the most sensitive parameter which should be determined with the comprehensive consideration of the efficiency and energy output, and the lower excess air ratio and higher CO(2)turbine inlet temperature are preferred for power generation.