Experimental study of a gas-injection refrigeration system using refrigerant mixtures to replace R404A

In this study, the performance characteristics of a gas-injection refrigeration system using ternary zeotropic mixtures of R32/R744/R1234yf were investigated to replace R404A. The performance of the gas-injection refrigeration system using R32/R744/R1234yf was measured and analyzed at various composition ratios. The test condition was set based on the refrigeration capacity B condition by the AHRI Standard 1251 (Indoor - 23 degrees C, outdoor 15 degrees C). The variation in the mass fraction of R32 affected the changes in latent heat and temperature glide. In addition, the injection pressure increased with an increase in the mass fraction of R744 owing to the low normal boiling point of R744. Based on the test results, the optimal composition ratio of R32/R744/R1234yf was determined to be 52/1/47 wt% considering the coefficient of performance (COP), refrigeration capacity, and global warming potential. R32/R744/R1234yf (52/1/47 wt%) showed a 9.56 % increase in COP and a 9.8 % decrease in life cycle climate performance (LCCP) compared with those of R448A owing to the lower compressor work and indirect emissions. The performance of the gas-injection refrigeration system using the mixture could be further improved by optimizing the system configuration.