Thermodynamic Study of Environment-Friendly R429A, R435A and R457A Refrigerants as Substitutes for Ozone Depleting R22 in Refrigeration and Air-Conditioning Systems

Abstract

Ozone depletion and global warming are presently the most serious global environmental problems and they have led to drastic changes in the refrigeration technology. Therefore, environment-friendly refrigerants have attracted a significant attention. This paper presents the thermodynamic study of non-ozone depleting R429A, R435A and R457A refrigerants as substitutes for R22 in air-conditioning systems. The results obtained showed that the vapour pressure curves of R429A, R435A and R457A are very close to that of R22 with advantage of lower deviation in pressure. These refrigerants also exhibited low pressure ratio and discharge pressure than R22 and their average discharge temperatures are 24.03, 13.54 and 28.53 % respectively lower than that of R22. They showed higher coefficient of performance than R22 with the average values of 2.47, 3.96 and 2.98 % respectively higher which shows better efficiency. The results also revealed R429A, R435A and R457A as energy efficient refrigerants as they exhibited lower power consumption per ton of refrigeration with average values of 2.14, 3.90 and 2.27 % respectively lower than that of R22. Generally, the three investigated environment-friendly refrigerants performed better than R22 and can effectively replace R22 in air-conditioning systems