Exergoeconomic analysis of a SOFC based trigeneration system with external reformer and dimethyl ether

In the present study, exergo-economic analysis of a combined solid oxide fuel cell (SOFC) with a gas turbine, a generator-absorber heat exchanger (GAX) and heating process heat exchanger for heating, cooling and power production as a tri-generation system is conducted. Also, an external steam reformer is applied to convert dimethyl ether as oxygenated fuel to hydrogen for the electrochemical process of the SOFC. The influence of the primary design parameters (fuel utilization factor and anode inlet temperature) on several variables (energy and exergy efficiencies, exergy destruction and unit costs of the power) are examined. Results show that energy efficiency of proposed system is 38% higher than standalone SOFC. It was found that the maximum exergy destructions occurred in afterburner, SOFC and recuperator. An increase in anode inlet temperature leads to reduction of exergy destruction in afterburner and fuelcell, while it has reverse effect on exergy destruction rate in recuperator. Unit cost of power is equal to 23.51 $⁄GJ at a specific condition and decreases with an increase in fuel utilization factor or increasing of anode inlet temperature. Increasing of utilization factor will increase all exergy efficiencies by 12%. The effect of an increase in anode inlet temperature on exergy efficiencies is positive but compared with the other parameter is lower and will increase them by 8%.