Thermodynamic and economic analyses and optimization of a multi-generation system composed by a compressed air storage, solar dish collector, micro gas turbine, organic Rankine cycle, and desalination system

Abstract

In this work, a hybrid system composed of a compressed air energy storage, a micro gas turbine, an organic Rankine cycle, a solar dish collector, and a multi effect distillation is presented as a combined power, heat, and fresh water production system. Energy and exergy analyses are applied to investigate thermodynamic performance of the system. The results show that the system consumes 278 kWh electricity and produces about 3.7 ton hot water during charging mode. Also, the system is capable of generating up to 523 kWh electrical energy and 2.5 ton potable water during the discharge period. The charge and the discharge period are 6.52 and 4 h respectively. Exergy analyses reveals that solar dish collector and combustion chamber are the major contributors for exergy destruction. Parametric analysis is employed to investigate the key parameters which have the major influence on the system performance. These parameters include cavern minimum and maximum pressures, gas turbine inlet temperature, dish collector aperture diameter, steam turbine inlet pressure, and desalinator feed water temperature. Optimization results show that round trip efficiency can rise from 65.2% to 70.35%, using upper limits of cavern minimum and maximum pressures. Besides, rising inlet temperature of gas turbine and restricting air cavern maximum and minimum pressures to their lower limits results in a 19.18% exergy efficiency improvement. Finally, economic analysis is performed to evaluate main cost and income sources of the system. As multi objective optimization shows, devising conditions that lead to produce more electrical energy improves system economic performance considerably.