Performance of Supermarket Booster Refrigeration System Using the Zeotropic Working Fluid CO2/R1234yf
To meet the need for energy efficiency improvement and substitution of traditional refrigerants in the field of supermarket refrigeration,a supermarket booster refrigeration system using the eco-friendly zeotropic refrigerant CO2/R1234yf is proposed in this study.A thermodynamic model is established and compared with that of a pure CO2 booster refrigeration system.The results show that the maximum COP(1.40)of the system using CO2/R1234yf was obtained under the optimal CO2 mass fraction(0.94)and discharge pressure(8.81 MPa).The COP of the CO2/R1234yf booster refrigeration system was significantly improved compared with the pure CO2 system,which increased by 7.25%when the ambient temperature was 35℃.The APF improvement of the CO2/R1234yf booster system was 2.68%-4.72%.The APF increased with an increase in the latitude of typical cities.The exergy efficiency of the CO2/R1234yf booster system first increased and then decreased with increasing CO2 mass fraction.The CO2/R1234yf booster refrigeration system exhibited the highest exergy efficiency(0.18)when the CO2 mass fraction was 0.95,which was 4.62%higher than that of the CO2 system.
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