Assessment of booster refrigeration system with eco-friendly working fluid CO2/halogenated alkene (HA) mixture for supermarket application around the world: Energy conservation, cost saving, and emissions reduction potential

For the scope of commercial supermarkets, the demand for energy efficiency improvement and environmentally-friendly working fluid of the refrigeration system is necessary. In this study, supermarket booster refrigeration system by using eco-friendly working fluid CO2/halogenated alkene (HA) mixture is proposed, and the mixture used in systems with two evaporation temperatures and operating modes affected by ambient temperature are studied. The energy efficiency, economic performance and emission reduction potential of the whole life cycle are conducted to compare with the pure CO2 booster refrigeration system. Furthermore, the influence of climate condition is discussed when used in 40 typical cities around the world. The results show the coefficient of performance (COP) of booster refrigeration system can be significantly improved by using CO2/HA mixtures. As the ambient temperature is 33 °C, the CO2/R1234yf (93/7) operates with the maximum COP of 1.367, which is 11.59% higher than that of pure CO2. Using CO2/HA mixtures in the booster refrigeration system can significantly improve the exergy efficiency of system. Moreover, the system using CO2/HA mixtures has higher annual performance factor and lower life cycle cost (LCC) than pure CO2. LCC of the system using CO2/R1234yf (94/6) is the lowest, and the reduction rate is 3.06∼5.59%. Meanwhile, the life cycle carbon emissions of systems in different climatic regions using CO2/R1234yf can be reduced by 2.39∼5.21%. The booster refrigeration system adopting CO2/HA mixtures is a promising alternative solution for commercial supermarket refrigeration and energy-saving.