As the pollution of the earth caused by the development of industry has become more and more serious, environmental protection has become an important issue of global concern, and the prevention of the destruction of the ozone layer in the atmosphere and global warming has attracted the attention of all countries in the world. The international government reached a consensus and signed relevant agreements . In the field of refrigeration and air conditioning, the destruction of the atmospheric ozone layer by CFCS and HCFCS and the global warming caused by energy consumption are issues that should be paid close attention to when designing compressors. As we all know, the selection of refrigerant is one of the many factors affecting compressor design that should be highly valued.
In order to develop a new compressor that uses alternative refrigerants, designers first encounter two problems: First, the compressor must re-size its working volume to meet the pressure requirements of different flow rates; second, the compressor Compatibility between various materials in contact with refrigerants, such as synthetic rubber and lubricants, must be addressed. In the past history, more than fifty substances have been used as refrigerants.
Many companies have switched to using HFC-134a in centrifugal chillers. CFC-12 CFC-12 is the first consideration to be replaced due to its wide application and leakage problems in automobile air conditioners. It can be replaced by HFC-134a in household refrigerators and car air conditioners. Used in the medium temperature and high temperature range, HFC-134a has a cooling capacity and efficiency similar to CFC-12.
However, under working conditions below -23°C, it loses its attractiveness due to its lower cooling capacity and efficiency than CFC-12. Although the ODP value of HFC-134a's ozone depletion potential is zero, its global warming potential GWP value is as high as 1300 (comparative value based on the GWP value of CO2), which will also affect its development and use in the long run. HCFC-22 HCFC-22 has been widely used in commercial refrigeration and commercial and residential air-conditioning and heat pumps. Its ODP value is much smaller than that of CFC-11 and CFC-12, which is only 0.055.
But its GWP value is quite high, about 1700. It is for these reasons that some European countries, such as Germany, are being quickly eliminated. There have been several mixed refrigerants as alternatives to HCFC-22. The American Refrigeration Association has recommended 4 types in its Refrigerant Alternative Evaluation Program (AREP): HFC-134a, R407C, R410A and R410B.