Investigation of heat recovery in CO2 trans-critical solution for supermarket refrigeration

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 sub-cooling (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.

► CO2 trans-critical system for supermarket refrigeration is studies in heat recovery mode.
► Control strategy is suggested so the system produces the highest COP possible.
► The analyzed CO2 system produces heating COP higher than a typical heat pump.
►  The studied CO2 system has lower energy consumption than conventional R404A.
► CO2 trans-critical systems for supermarkets refrigeration are efficient solutions in cold climates.