Thermodynamic Study and Exergetic Analysis of the Integrated SOFC-GT-Kalina Power Cycle

In this paper the SOFC-GT-Kalina (solid oxide fuel cell, gas turbine, and Kalina cycle) integrated system is proposed. The system uses Kalina cycle as the bottoming cycle to recovery the waste heat from the gas turbine to generate power. Kalina cycle uses ammonia-water mixture as the work fluid which has sliding-temperature boiling characteristics. By comparing with the SOFC-GT-ST (solid oxide fuel cell, gas turbine, and steam turbine cycle) system as the reference system, the systems are simulated by Aspen Plus through analyzing the overall system performance. Electrical and exergy efficiency of the proposed system are 74.41% and 71.93%, and electrical and exergy efficiency of the reference system are 71.45% and 69.07%, proving the superiority of Kalina cycle for waste heat recovery. In addition, the exergy losses of each component are studied, and the detail performance analysis of the proposed system is presented, consisting of thermal analysis, exergy analysis and EUD (Energy-utilization diagram) analysis, which intuitively disclosed the causes of exergy loss. Additionally, it was revealed that there exists an optimal current density at 350 mA/cm2 for power and power density.