Thermodynamic performance analysis a power and cooling generation system based on geothermal flash, organic Rankine cycles, and ejector refrigeration cycle; application of zeotropic mixtures

Abstract

Regarding the important role of combined cooling and power (CCP) systems in improving the efficiency of power plants, and also the ability of ORC and ERC systems in the exploitation of low-to medium-grade energy sources, a novel CCP system is presented which is based on geothermal flash cycle as topping cycle, organic Rankine cycle, and ejector refrigeration as the bottoming cycle for power and cooling generation aims. This work proposes a thermodynamic and parametric analysis of the proposed system where the ORC and ERC cycles employ different mixtures of zeotropic fluids as the working fluid. The integration of ORC and ERC systems with zeotropic mixtures presents the considerable capability to combine their superiority and further enhance the system performance considerably. The superiority of the proposed system, which combines the advantages of zeotropic mixtures with ORC and ERC positive aspects, is revealed through the energy and exergy analysis. The results revealed some precious facts; for instance, the total thermal and exergetic efficiencies are calculated by 18.16% and 59.16%, correspondingly. Also, the COP and the cooling capacity of the ERC unit is obtained 0.1224 and 93.73kW, respectively. Besides, the best exergy efficiency and the lowest exergy destruction is evaluated for the system with Isopentane (0.3)/R142b (0.7) as the working fluid. Also, from the parametric study, it can be inferred that decreasing the separator pressure and increasing the heat exchanger inlet temperature leads to higher energy and exergy efficiency.