Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector 63 S ection 02 Th e research project “Evaluation of two stores with supercritical systems with CO2 as refrigerant” (Arias et al, Energiteknik, 2007) collected and evaluated data from two supermarkets, one store owned by COOP in the northern part of Sweden, Luleå and one ICA store in the southern part, Gothenburg. The work was carried out in a research project sponsored by the three leading supermarket chains in Sweden and the Swedish Energy Agency. The result reported here is from the COOP store in Luleå where they had most recorded data. competitive from energy consumption point of view. Due to the characteristics of the supercritical process the possibility for heat recovery is very good which can be beneficial for the total system efficiency if it can be used. One cited evaluation of a number of Norwegian stores with CO2 indicate a better performance than similar stores with conventional systems. CO2 will - when used in supercritical systems - operate at higher pressures than other refrigerants traditionally used in the RAC industry. Moreover, the supercritical process requires a different control strategy to achieve an acceptable performance. To introduce CO2 on the market will require that these and other competencies to use CO2 are spread to the RAC servicing sector. A full range of systems for CO2 both with cascade and supercritical systems are commercially available today. Background data/information given for this case comes from a report by Jaime Arias et al., from the Department of Energy at the Royal Institute of Technology in Stockholm (Arias et al, Energiteknik, 2007). Information is also from Green&Cool and their Norwegian partner Kulde Teknisk regarding the six Norwegian stores. The description is based on the data received from these sources, butas regards the selection of information and interpretation , the responsibility is with the author of this report. 2.7.1 Evaluauation of carbarbarbon dioxide supupermararket in Sweden Fig. 2.19 Schematic flow chart of type of supercritical supermarket CO2 system installed in Luleå. The system is also connected to the heat recovery system (not shown). Machine roomEvaporatorsMedium temperatureDisplay cases/roomsChilled foodOne stagecompressionGas coolerEvaporatorsLow temperatureDisplay cases/roomsFrozen foodTwo stagecompressionGas coolerDry Cooler