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This paper aims to provide comprehensive 4E (energy, exergy, exergoeconomic, and exergoenvironmental) and advanced exergy analyses of the Refrigeration Cycle (RC) and Heat Recovery Refrigeration Cycle (HRRC) and comparison of the performance with R744 (CO2) and R744A (N2O) working fluids. Moreover, multi-objective optimization of the systems has been considered to define the optimal conditions and the best cycle from various perspectives. In HRRC, heat recovery is used as a heat source for an organic Rankine cycle. The energy and exergy analysis results show that utilizing HRRC with both refrigerants increases the coefficient of performance (COP) and exergy efficiency. COP and exergy efficiency for HRRC-R744 have been obtained 2.82 and 30.7%, respectively. Due to the better thermodynamic performance of HRRC, other analyses have been performed on this cycle. Exergoeconomic analysis results show that using R744A leads to an increase in the total product cost. Total product cost with R744 and R744A have been calculated by 1.56 $/h and 1.96$/h, respectively. Additionally, to obtain the processes' environmental impact, Life Cycle Assessment (LCA) is used. Exergoenvironmental analysis showed that using R744A increases the product environmental impact by 32%. Owning to the high amount of endogenous exergy destruction rate in the compressor and ejector compared to other equipment, they have more priority for improvement. Multi-objective optimization has been performed with exergy efficiency and total product cost objective functions as well as COP and product environmental impact for both refrigerants, which indicates that HRRC-R744 has better performance economically and environmentally. In optimal condition, the value of exergy efficiency, total product cost, COP, and the product environmental impact have been accounted for by 28.51%, 1.44 $/h, 2.76, and 149.01 mpts/h, respectively.

Two cogeneration cycles based on gas turbines have been compared by means of thermoeconomic and environmental analyses. The analyzed cogeneration systems are gas turbine, organic Rankine cycle (GT + ORC) and an integrated system including gas turbine, organic Rankine cycle, and ejector refrigeration cycle (GT + ORC + ERC). This work has focused on environmental considerations and thermoeconomic evaluation to decrease destruction cost and environmental impacts. The examination of cycles is conducted from energy, exergy, exergoeconomic, and exergoenvironmental (4E) perspectives. A computer MATLAB program is used to generate the simulation results, and the REFPROP 9.1 database is utilized to get thermodynamic properties of the working fluids. The use of the refrigeration evaporator in GT + ORC + ERC increased energy and exergy efficiencies. Multi-objective optimization results indicate that the waste heat utilization in the trigeneration system is more effective in all aspects. In optimal conditions, the exergy efficiency and destruction cost of the GT + ORC + ERC system reached 40.76% and 151.95$ h À1 , respectively. Moreover, optimization is performed by means of energy efficiency and destruction environmental impact as objective functions, and the optimum values are obtained at 30.67% and 46,918.30 mpts h À1 , respectively.

This paper aims to provide comprehensive 4E (energy, exergy, exergoeconomic, and exergoenvironmental) and advanced exergy analyses of the Refrigeration Cycle (RC) and Heat Recovery Refrigeration Cycle (HRRC) and comparison of the performance with R744 (CO2) and R744A (N2O) working fluids. Moreover, multi-objective optimization of the systems has been considered to define the optimal conditions and the best cycle from various perspectives. In HRRC, heat recovery is used as a heat source for an organic Rankine cycle. The energy and exergy analysis results show that utilizing HRRC with both refrigerants increases the coefficient of performance (COP) and exergy efficiency. COP and exergy efficiency for HRRC-R744 have been obtained 2.82 and 30.7%, respectively. Due to the better thermodynamic performance of HRRC, other analyses have been performed on this cycle. Exergoeconomic analysis results show that using R744A leads to an increase in the total product cost. Total product cost with R744 and R744A have been calculated by 1.56 $/h and 1.96$/h, respectively. Additionally, to obtain the processes' environmental impact, Life Cycle Assessment (LCA) is used. Exergoenvironmental analysis showed that using R744A increases the product environmental impact by 32%. Owning to the high amount of endogenous exergy destruction rate in the compressor and ejector compared to other equipment, they have more priority for improvement. Multi-objective optimization has been performed with exergy efficiency and total product cost objective functions as well as COP and product environmental impact for both refrigerants, which indicates that HRRC-R744 has better performance economically and environmentally. In optimal condition, the value of exergy efficiency, total product cost, COP, and the product environmental impact have been accounted for by 28.51%, 1.44 $/h, 2.76, and 149.01 mpts/h, respectively.