systems still have a large development potential when systems applying R744 as the only refrigerant. The
system architecture has to be adapted to the working fluid properties, especially with respect to the
maximizing of the system efficiency when these units are operated at elevated ambient temperatures. The
objective of this study was to investigate the energy required for different R744 commercial refrigeration
systems at various global locations. The most promising system configurations were described and
performances were modelled for high ambient temperature operations based on experimental results from
laboratory investigations and pilot shops in various countries.
The energy consumption of these R744 system configurations were compared with measured values for
H(C)FC supermarket refrigeration systems. It was shown that the efficiency level of R744 systems may be
increased to exceed the baseline HFC system even at ambient temperatures up to 35-40°C by applying ejector
supported parallel compression. This means that the systems may be energy competitive at peak power even in
the hottest climates of the world. At lower ambient temperatures, the efficiency of the R744 systems is always
superior, resulting in seasonal efficiency of the R744 systems that clearly outperforms the H(C)FC systems.