Thermo-economic analysis and optimization of a solar-driven ammonia-water regenerative Rankine cycle and LNG cold energy

A configuration consisting of solar-driven ammonia-water regenerative Rankine cycle and LNG cold energy recovery system is analyzed from the thermo-economic viewpoint. An effective pinch analysis is carried out in ammonia-water evaporator which causes improvement in the thermodynamic performance and output power of the system. Also, heat exchangers are simulated by using heat transfer correlations of shell and tube heat exchanger in detail. The results of base condition show a suitable thermo-economic performance of natural gas system and illustrate the importance of using natural gas system. Also, solar collector and condenser of ammonia-water cycle, have the highest value of total cost rate. The parametric analysis results show that in high inlet pressure of ammonia-water turbine the exergy efficiency and the total cost rate of the system have more suitable values while the net output power of the system decreases. Finally, the thermo-economic performance of the system is optimized using NSGA-II. Condensation temperature, ammonia mass fraction and ammonia-water turbine inlet pressure are considered as the effective parameters in optimization process. In optimum design condition, objective functions including net output power and the total cost rate of the system have the values of 4190.2 kW and 1181 $/h, respectively.