Effect of recycling on the thermodynamic and thermoeconomic performances of SOFC based on trigeneration systems; A comparative study

In this study, methane fed trigeneration systems producing power, cooling and heating by means of combination of SOFC, generator-absorber heat exchanger (GAX) absorption refrigeration and heat recovery systems are proposed. Accentuating on the gas recycle of anode and cathode of the SOFC stack, performance of four different suggested configurations are compared with each other. Thermodynamic model is developed for the proposed systems using the mass, energy and exergy balance equations. To give information about the viability of the systems, economic point of view is also taken into account. Meanwhile, the comparison is performed through parametric studies in which the effects of anode recycle and cathode recycle on the net electrical power, energy and exergy efficiency as well as on the unit product cost of trigeneration systems are investigated. The results show that the total energy efficiency of the trigeneration system with anode gas recycle (Tri-SOFC-AR) is 82.5% which is almost 6% larger than that of the simple base case system proposed (Tri-SOFC). In addition, results revealed that among the proposed systems, the one in which the anode and cathode gas recycle (Tri-SOFC-ACR) is used shows the highest exegetic and economic performance in comparison with the other configurations.