Ozone depletion potential
The ozone layer in the upper atmosphere provides our filter for ultraviolet radiation that can be harmful for health. The researchers found that the thinning of the ozone layer, because of emissions of CFCs, halons and bromine compounds. The ozone depletion potential (ODP) refrigerant its impact on atmospheric ozone, and the starting point is usually taken ODP = 1 for CFC R11.
After a series of intensive meetings and negotiations, the Montreal Protocol on Substances that Deplete the Ozone Layer was finally agreed in 1987. Signatories agreed to the stage of production of these substances in 1995. Refrigerant emissions it was only about 10% of the total, with the remainder being made aerosols, solvents and insulation material. Refrigeration industry, rapidly moved from CFCs to HCFCs; R22 and replacement of HCFC mixtures. In the subsequent revision of the Protocol, phase schedule for HCFCs also created. R22 that HCFCs, has a much lower ODP than CFCs, but was considered necessary to remove all ozone-depleting substances, and the Protocol HCFCs will be eliminated by 2030.
This put an end to R22. In addition, the European Union has developed a much stronger Regulation 2037/2000, which banned all new HCFC equipment in 2004, banned the sales of new refrigerant HCFC service in January 2010 and secondary refrigerant in 2015.
Replace chlorine containing CFCs and HCFCs, a chemical company have developed a series of hydrofluorocarbons (HFCs). HFC tend to have somewhat poorer thermodynamic properties than that of R22, and as one substance, as a rule, they do not exactly match the performance of the chemicals they are designed to replace. While R134a, first of HFCs to become available, closely in accordance with R12, other refrigerants now widespread use of mixtures of two or three HFCs (see Table. 3.1). Fig. 3.2 illustrates the ideal, or the theoretical performance of some of the most widely used together with HFC ammonia at boiling in 5C.
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