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Summary: With the temperature glide in saturation states, the mixture working fluids have the advantages in thermal energy conversion. In this study, through the investigation in optimum mass fractions of multicomponent mixture working fluids, the economic performance enhancement of the organic Rankine cycle system is obtained for recovering waste heat from engine. The zero ozone‐depletion‐potential and dry working fluids of R236fa, R245fa, and R1336mzz(Z) are selected as the components of multicomponent mixtures in the system. The net power output, heat transfer calculation, and apparatus cost evaluation are employed to evaluate the power cost of the organic Rankine cycle system. Parameters of temperatures of waste heat sources and efficiencies of expanders are taken into account. The comparisons of economic performances for single‐component working fluid and multicomponent mixtures with optimum mass fractions are proposed. The results show that R245fa, having a levelized cost of energy, LCOE, of 8.75 × 10−2 $/kW‐h, performs the best for single‐component working fluids, better than R236fa by 1.6% and R1336mzz(Z) by 8.3%. All the two‐component mixtures are superior to their single‐component working fluids in economic performance. Among the three two‐component mixture working fluids, R1336mzz(Z)/R236fa has the lowest LCOEmin, 8.57 × 10−2 $/kW‐h, followed by R236fa/R245fa and R245fa/R1336mzz(Z). In addition, R236fa/R245fa/R1336mzz(Z) mixture, which has a LCOEmin of 8.47 × 10−2 $/kW‐h, economically outperforms all other working fluids and has a lower LCOEmin than R236fa/R245fa by 1.7% and R245fa/R1336mzz(Z) by 2%. [ABSTRACT FROM AUTHOR]

A finite temperature difference heat transfer method and irreversibility analysis have been developed for investigating the effects of subcooling on coefficient of performance, cooling water pressure drop of condenser, and heat exchanger area for R1234yf, R1234ze, R22, R134a, and R410A in a single vapor-compression refrigeration system. In order to satisfy the increasing cooling load for subcooling in a condenser, the heat exchanger size or cooling water pumping power that corresponds to initial cost or operating cost, respectively, is increased. The optimum degree of subcooling in a refrigeration system with superior performance and least initial cost or operating cost is obtained numerically. The results show that the maximum coefficient of initial cost saving and coefficient of operating cost saving and their corresponding optimum degree of subcooling increase with condensation temperature. At a higher inlet temperature of cooling water, the optimum degree of subcooling turns out to be smaller for all refrigerants. The results are expected to facilitate the prospective design of a vapor-compression refrigeration system for using alternative refrigerants. [ABSTRACT FROM PUBLISHER]