The original wall-mounted split air conditioners and refrigerators used toxic gases such as ammonia and methyl chloride. The leakage of this type of gas will cause a major accident. Thomas Mickley invented chlorofluorocarbon gas in 1928 and named it Freon. This refrigerant is much safer for humans, but it is harmful to the atmospheric ozone layer. Freon is a trademark of DuPont’s CFC, HCFC or HFC refrigerants. The name of each refrigerant also includes a number to indicate the molecular composition of its components (such as R-11, R-12, R-22, R- 134).
Among them, R-22 HCFC refrigerant, which is the most widely used in the field of direct evaporative cooling products, will stop being used in new production equipment in 2010, and will be completely stopped in 2020. R-11 and R-12 have been discontinued in the United States. As an alternative, some refrigerants that are not harmful to the ozone layer have been put into use, including the refrigerant R-410A under the trade name "Puron". R290 and R32 new environmentally friendly refrigerants are also gradually entering the market. R290 contains only carbon and hydrogen in its molecules, not chlorine and fluorine, and has zero ozone depleting potential (ODP).
