The thermodynamic analysis of new combined cycle using Sabalan geothermal wells and LNG cold energy

A new configuration base on Sabalan geothermal wells is proposed to utilize two wells with different thermodynamic properties in Sabalan region in Iran and generate more power as well as supply of natural gas from Liquefied Natural Gas (LNG). A Kalina cycle and Transcritical CO2 Rankine cycle are using sabalan geothermal wells as a heat source and LNG as a thermal heat sink. A comprehensive parametric study is investigated to understand the characteristics of the system. The effects of the separator 1&2 pressures, pinch point temperature difference in the evaporators, the higher pressure of the Kalina cycle, the ratio of the Transcritical higher pressure to the critical pressure and pressure of LNG pump are studied on the power generation and thermal and exergy efficiencies. The results show that the thermal and exergy efficiencies can be increased by increasing separator 1&2 pressures and LNG pump. Also decreasing the higher pressure of the Kalina cycle and pinch point temperature of evaporators lead to increasing the net output power, thermal and exergy efficiencies. Additionally, exergy analysis results showed that the highest exergy destruction rate belongs to the heat exchanger 1&2. Optimization of the proposed cycle is performed by using genetic algorithm method, and it is observed in the optimal condition that the net output power, thermal efficiency, and exergy efficiency can be obtained as 30610 kW, 29.16%, and 56.92%, respectively. The results of this study indicate that the net output power and thermal efficiency is better performance compared to the previous studies.