Transcritical CO2 Refrigeration System Integrated with a Heat Pump for Heat Export to District Heating

The rising global temperatures associated with global warming enforce to reduce the emissions from heating and cooling systems. Conventionally, the refrigeration and space heating demand of a supermarket is catered by the refrigeration system and a natural gas fired boiler/electric boiler/district heating network, respectively. The environmental and economic advantage of replacing these systems with a conventional booster CO2 refrigeration system with heat recovery and an integrated heat pump (CB_HP) were analysed in this study. The variation in ambient temperature, electricity price, heat selling price and heating and refrigeration demand of the supermarket on a cold day in Stockholm (Sweden) were considered for the analysis. Furthermore, the optimization of the economic performance of CB_HP for varying gas cooler pressure and outlet temperature was carried out. The results show that the total emissions and operating cost could be reduced by up to 94 % and 91 % as the conventional systems were replaced by CB_HP, respectively.