1. CFC Refrigerant: Freon refrigerants, the components of fluorine F, chlorine Cl and carbon C, are listed as a controlled substance by the Montreal Protocol because of their greatest damage to the ozone layer.
2. HCFC Refrigerant: The elements hydrogen H, chloride Cl, fluorine F and carbon C are regarded as the most important transitional substitutes for CFC because their ozone layer destruction coefficient is only a few percent of R11.
3. HFC Refrigerant: The ozone layer destruction coefficient of hydrogen H, fluorine F and carbon C is 0, but the climate warming potential is very high.Under the compliance requirements of the Amendment of Montreal Agreement, China is required to freeze the production and use of HFCs at baseline levels beginning in 2024. (Baseline is the average HFCs from 2020 to 2022, plus 65% of the baseline HCFC level in CO2 equivalent) The production and use of HFCs will not exceed 90% of the baseline from 2029, 70% from 2035, 50% from 2040, and 20% from 2045.
Non-azeotropic refrigerant mixtures refer to refrigerants that are formed by mixing two or more substances.
| Generations | Category | Main Products | ODP | OWP | Features and Current Circunstances |
| 1G | CFCs | R11,R12,R113 | 1 | 4000 | Seriously destroys the ozone layer. In 2010, it was phased out and banned from production in the global market. The Ministry of Ecology and Environment of my country clarified the illegal recognition of R11 in the polyester industry |
| R114,R115,R500 | |||||
| R502 | |||||
| 2G | HCFCs | R22 | 0.055 | 1810 | In the long run, the ozone layer has been severely damaged, and developed countries are close to complete elimination. Developing countries enter the stage of production reduction |
| R123 | 0.02 | 77 | |||
| R141b | 0.12 | 725 | |||
| 3G | HFCs | R134a | 0 | 1430 | It has no impact on the ozone layer, and the greenhouse effect is much higher than that of carbon dioxide and second-generation refrigeration. Currently, developed countries are in the early stage of phase-out, and developing countries have entered the quota reference period. |
| R125 | 0 | 3500 | |||
| R32 | 0 | 675 | |||
| R410a | 0 | 2100 | |||
| 4G | HFOs | R1234yf, R1234ze | 0 | low | No fluorine refrigerant, high environmental friendliness, but the refrigeration effect and safety are not as good as the previous generation. Shortcoming of related patents limite, equipment high cost and flammable feature |
| HCs | R600a,R290 | 0 | low |
