Theoretical performance comparison for a regenerator-enhanced three-stage auto-cascade refrigeration system using different zeotropic mixed refrigerants

• Published in: Energy and buildings Vol. 283; p. 112815
• Main Authors: He, Yongning, Wu, Huihong, Xu, Ke, Zhang, Yeqiang, Wang, Tao, Wu, Xuehong, Cheng, Chuanxiao, Jin, Tingxiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.03.2023
• Subjects: Performance comparison; Ratio optimization; Refrigerant substitution; Three-stage RACR system; Ratio optimization; Performance comparison; Refrigerant substitution; Three-stage RACR system
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2023.112815

•A novel three-stage RACR was proposed to improve the performance of ACR.•The R134a/R23/R14 RACR system performed better than the ACR system.•The influence of the refrigerant ratio on RACR performance was investigated.•Different hydrocarbons were provided as alternatives to R134a and R23.•R600/R170/R14 performed the optimum performance in the RACR system. Auto-cascade refrigeration (ACR) systems are widely used at low temperatures. The selection and ratio optimization of zeotropic refrigerants in ACR systems have an important impact on system performance and environmental protection. This study proposes a three-stage regenerator-enhanced auto-cascade refrigeration (RACR) system. Under certain working conditions, the theoretical performances of the three-stage R134a/R23/R14 ACR and RACR systems were compared, and the influence of the refrigerant mixture ratio on the RACR system performance was explored. The system performances of replacing R134a and R23 with different hydrocarbons were compared under different working conditions. The results demonstrated that RACR performed better than ACR alone. A reasonable adjustment to the mixed refrigerant ratio improved the energy efficiency of the RACR system. Water-cooling conditions for the RACR system were suggested, under which the coefficient of performance, thermodynamic perfectness, and exergy efficiency of R600/R170/R14 were 13.8 %, 12.4 %, and 8.4 % higher than those of R600/R23/R14, respectively. The environmental policy, safety requirements, and energy efficiency were considered to obtain −100 °C, R600/R170/R14 with mass fractions of 0.24/0.12/0.64 was the best choice in a water-cooled RACR system.