Exergoeconomic analysis of a novel integrated transcritical CO2 and Kalina 11 cycles from Sabalan geothermal power plant

A new integrated cycle based on different real temperatures and pressures on Sabalan geothermal power plant, located in Iran, has been proposed and thermodynamic and exergoeconomic analyses are performed. The Kalina and Transcritical Rankine cycles are used as bottoming cycles and an algorithm are applied to find the exact location of the pinch points in heat exchangers. Also, a parametric study carried out to reveal the effects on the thermodynamic and exergoeconomic performance of the integrated cycle of such important parameters as separator 1 pressure, separator 2 pressure, pinch point temperature difference in the evaporators, higher pressure of the Kalina cycle and the ratio of the Transcritical cycle higher pressure to the critical pressure. Finally, the proposed cycle performance is optimized from the thermodynamic and exergoeconomic viewpoints. The results show that for the integrated geothermal power plant, the power generation, thermal efficiency, exergy efficiency and power specific cost rate are calculated to be 19,448 kW, 16.63%, 63.78%, and 4.521 $/GJ, respectively, which indicate that the proposed cycle has improved thermodynamically and exergoeconomically compared to previous studies.