Thermodynamic Analysis of Solid Oxide Fuel Cell Based Combined Cooling, Heating, and Power System Integrated with Solar-Assisted Electrolytic Cell

Syngas fuel such as hydrogen and carbon monoxide generated by solar energy is a promising method to use solar energy and overcome its fluctuation effectively. This study proposes a combined cooling, heating, and power system using the reversible solid oxide fuel cell assisted by solar energy to produce solar fuel and then supply energy products for users during the period without solar radiation. The system runs a solar-assisted solid oxide electrolysis cell mode and a solid oxide fuel cell mode. The thermodynamic models are constructed, and the energetic and exergetic performances are analyzed. Under the design work conditions, the SOEC mode’s overall system energy and exergy efficiencies are 19.0% and 20.5%, respectively. The electrical, energy and exergy efficiencies in the SOFC mode are 51.4%, 71.3%, and 45.2%, respectively. The solid oxide fuel cell accounts for 60.0% of total exergy destruction, caused by the electrochemical reactions’ thermodynamic irreversibilities. The increase of operating temperature of solid oxide fuel cell from 800 °C to 1050 °C rises the exergy and energy efficiencies by 11.3% and 12.3%, respectively. Its pressure from 0.2 to 0.7 MPa improves electrical efficiency by 13.8% while decreasing energy and exergy efficiencies by 5.2% and 6.0%, respectively.