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In this study, comprehensive energy, exergy, and economic modeling, and optimization of a flash-binary geothermal system, were carried out for power and hydrogen production. The binary system is a combination of a dual-pressure organic Rankine cycle and proton exchange membrane electrolyzer. For performance improvement of dual-pressure organic Rankine cycle, zeotropic mixtures were used as the working fluids. The multi-objective Genetic algorithm was employed to optimize the system performance. According to the obtained results, the highest rate of exergy destruction was obtained for the steam turbine with a value of 16.42 kW. For the base case simulation, the energy and exergy efficiencies of the proposed system were obtained by 16.66 % and 58.03 % , respectively; also, the generated power, overall exergy destruction, and hydrogen production capacity were calculated by 114.53 kW , 82.755 kW , and 0.306 kg · hr − 1 , respectively. For the multi-objective optimization mode, the best performance was calculated for Pentane (0.467)/Butane (0.533) with energy and exergy efficiencies and hydrogen production of 16.67 % , 58.14 % , and 0.37 kg · hr − 1 . Moreover, the optimized payback period and NPV were around 5.52 years and 402600 $ , respectively. • Proposal of a flash-binary geothermal system for power and hydrogen production. • Using zeotropic mixtures for performance improvement of dual-pressure ORC. • Analyzing economic aspects of the proposed system for probable investment. • Energy and exergy efficiencies of 16.67 % and 58.14 % for the optimized mode. • Optimized payback period and total profit of 5.52 years and 402800 $. [ABSTRACT FROM AUTHOR]

In this paper, a novel geothermal-based trigeneration system producing electricity, cooling, and freshwater is devised. The whole setup comprises a flash-binary geothermal cycle, an ejector refrigeration cycle, a dual-pressure organic Rankine cycle, and a reverse osmosis unit. In the dual-pressure organic Rankine cycle, the utilization of the zeotropic mixture is examined for performance improvement. The overall system is analyzed from energy, exergy, and economic viewpoints. Likewise, the system is inspected by the thermodynamic and economic sensitivity analyses based on the best working fluid. By specifying the Butene/Isopentane zeotropic mixture as the best working fluid, it is revealed that from 10932 k W of the input exergy to the system, 5561.74 k W is destructed within different components. In this way, the recovered exergy rate by net output electricity is equal to 3633.33 k W , by cooling load is 1663.44 k W , and by freshwater is 104 k W. Also, the optimum net output power and total energy and exergy efficiencies were obtained to be 3.65 MW , 25.06 % , and 35.06 % , correspondingly. In this situation, the sum unit cost of products and payback period of the system were 14.50 $. GJ − 1 and 3.66 years , respectively. • Energy, exergy, and economic (exergoeconomic + NPV) analyses of a new geothermal system. • Integration of a flash-binary geothermal cycle with an ERC, a DORC, and a RO unit. • Performance enhancement by determining the best zeotropic working fluid of the DORC. • Optimum working fluid has been predicted as Butene (0.442)/Isopentane (0.558). • Optimum exergy efficiency and payback period are 35.06% and 3.66 years, separately. [ABSTRACT FROM AUTHOR]