Evaluation of zeotropic mixtures as refrigerants in a dedicated subcooling system of a CO2 refrigeration plant

Prof. Baomin Dai suggested in 2018 that the use of zeotropic mixtures with high glide could provide energy improvements as refrigerants in dedicated mechanical subcooling systems for CO2 plants due to matching of temperature profiles between the evaporation of the refrigerant and the CO2 during the subcooling. This communication addresses this hypothesis from a theoretical point of view, selecting refrigerant blends that could be used in the subcooling system, and then presents the experimental evaluation of three mixtures in a real plant. Experimental evaluation has been done using a water-to-water CO2 transcritical refrigeration plant at three heat rejection levels for an evaporation level of -10 ºC. The work will compare the energy results and highlight the operation of the main components of the cycle.