Thermodynamic analysis of fuel-cell-based combined cooling, heating, and power system integrated solar energy and chemical looping hydrogen generation

Abstract

A novel solid-oxide-fuel-cell-based cooling, heating, and power (CCHP) system integrated chemical looping hydrogen generation is proposed, in which the chemical looping hydrogen generation realizes the high-efficiency CO2 capture and provides hydrogen to fuel cell, avoiding carbon deposition caused by the direct reaction of methane. The high-temperature solar heat collector is integrated to assist the fuel cell subsystem in achieving high-efficiency power generation and energy cascade utilization. The thermodynamic models of components are constructed, and the energy and exergy performances under the design conditions with or without solar energy are compared and analyzed. Through validating the thermodynamic models, the simulation results indicate that the energy and exergy efficiencies in cooling mode are 78.02% and 45.92%, respectively. The energy efficiency in heating mode reduces by 5.08%, while the exergy efficiency increases by 0.67%. The CO2 capture rate of the proposed system reaches 99.96% and the CO2 purity is about 99.59%. The energy consumption of CO2 capture in the proposed system reduces by 69.37% compared to the conventional system. The sensitivity analysis of key parameters such as fuel cell operating temperature and direct normal irradiance on system performances are performed. The results show the total energy and exergy efficiencies can be improved by properly increasing the SOFC operating temperature. Although the energy and exergy efficiencies slowly drop with the increasing direct normal irradiation, the energy output increases by 6.10% and 4.95% in cooling and heating mode from 500 W/m2 to 1000 W/m2, respectively.