Commercial refrigeration system with CO2 as refrigerant. Experimental results

Various field-test systems using CO 2 as the only refrigerant have been installed since December 2001. The most recent installation, in operation since January 2003, is analysed in this paper. The seasonal COP is calculated, based on prior laboratory measurements, and a comparison is made with a conventional direct expansion system using R404A. The total annual energy consumption of the installed CO 2 system is estimated to be about 8% higher than the equivalent R404A solution. Some possible improvements are pointed out. It is still possible to further improve efficiency and approach the efficiency of present R404A direct expansion systems. The cost of the CO 2 installation is compared to the cost of an equivalent direct expansion R404A installation, the most economic among the various types of commercial refrigeration systems. The CO 2 installation is estimated to be, today, about 10% more expensive.