Comparative analysis of energy improvements in single transcritical cycle in refrigeration mode

• A performance analysis of three configurations in transcritical cycle is realized.
• Recommended conditions for use of ejector in transcritical cycle are presented.
• A cooling capacity comparison among three configurations is presented.

One solution to increase the energy performance in transcritical cycles in refrigeration mode is the coupling of elements to the cycle. Thus, this paper presents the analysis of configurations for achieving an increase in the performance, and in order to achieve it, it is proposed to include an internal heat exchanger, an ejector and a turbine. Both the ejector and the turbine have been considered as a solution for the irreversibilities that are produced in the expansion stage during the cooling cycle. A comparison among the three proposals is carried out, and the adequate operational conditions to which it is recommended to use one or other configuration are analyzed. The results show that the use of the ejector is recommended for output temperatures above 27 °C in the gas cooler. By doing this, an increase in the coefficient of the energy performance was achieved, which is superior to the one obtained when an intermediate heat exchanger is used. Finally, the increase in the COP as a function of the evaporation technology in each cycle is higher in the analyzed proposals, in which the increase reached is 35.85% when using an ejector, 24.21% when using a turbine, and 25.74% when using the internal exchanger. All of the configurations have been simulated under conditions of medium temperature refrigeration.