Using computer simulation modeling this study investigates the performance of a CO2
trans-critical system with heat recovery from the de-superheater. The influence of subcooling
(or further cooling) in the condenser/gas cooler on system performance is investigated.
Following the suggested control strategy in this study, the extra operating energy
demand required to recover the needed heating energy from the analyzed CO2 system is
smaller than what a typical heat pump would require for the same load. This is the case for
almost all ambient temperatures over a full season. When taking the simultaneous heating
and cooling loads into account, the CO2 trans-critical system has lower annual energy
usage in an average size supermarket in Sweden when compared to a conventional R404A
refrigeration system with separate heat pump for heating needs. CO2 trans-critical systems
are efficient solutions for simultaneous cooling and heating needs in supermarkets in
relatively cold climates.