In the last decade several plant configurations and components have been proposed to increase the
efficiency of CO2 refrigeration systems. Among these, subcooling is considered a simple but effective
solution, together with the employment of adiabatic cooling systems at the gas cooler.
In this work, a fully instrumented CO2 booster plant installed in a supermarket is considered, to compare
parallel compression, subcooling and adiabatic cooling. Subcooling is performed taking advantage of
chilled water available from the HVAC system. The experimental data are used to validate a model for
the comparison on a yearly basis.
Parallel compression and subcooling show to be almost equivalent in terms of yearly energy use,
while the adiabatic cooling system gives the best performance.
Comparisons reveal that the subcooler cooling capacity should be chosen carefully to avoid
oversizing, while the influence of the EER for the chiller appears quite small. Subcooling performed
at the expense of an HVAC plant shows to be an interesting solution, while a great benefit was
experienced with the employment of an adiabatic gas cooler.
