Thermodynamic and exergic modelling of a combined cooling, heating and power system based on solid oxide fuel cell

Abstract

In this research, thermodynamic and exergic analyses have been carried out on a combined cooling, heating and power cogeneration system that includes a solid oxide fuel cell and a single-effect lithium bromide absorption chiller. Results indicate that by increasing the system inlet air flow rate, the overall efficiency of the hybrid system is reduced, due to the reduction of the cell’s working temperature and exhaust gases temperature; while an increase in the working pressure of the system has no effect on its efficiency. The results also show that by raising the temperature of exhaust gases, the rate of exergy destruction diminishes, while the rate of exergy loss in the hybrid system increases. In the absorption chiller cycle, the maximum exergy destruction rate occurs in the generator, and the minimum rate is achieved in the pressure-reducing valve, between the evaporator and the condenser. Also, in the fuel cell cycle, the highest exergy destruction rate occurs in the heat exchanger of the inlet air to the cell, and the lowest exergy destruction rate occurs in the two water pumps. Moreover, the entropy generation rate and the exergy destruction rate of the fuel cell cycle are higher than those of the chiller cycle.