Alternative refrigerants for the primary circuit of an indirect commercial refrigeration cascade system.

F-Gas Regulation has fixed a GWP limit of 150 for centralized refrigeration systems with capacity over 40 kW in Europe from 2022 on, meaning the end of R-134a as primary refrigerant in direct R-134a/CO2 cascade systems. They can be reconverted into indirect cascades using a secondary loop, bringing the possibility to use primary refrigerants with reduced security. This communication presents the experimental results of the energy evaluation of an indirect cascade using CO2 as low temperature refrigerant and different refrigerants in the high temperature cycle (R-134a, R-152a, R-1234ze(E), R-290 and R-1270). The system serves a medium temperature cabinet and a low temperature island placed inside a climatic chamber under laboratory conditions. The evaluation covers three heat rejection levels (18.9, 31.8 and 42.3ºC).