Traditional refrigerants of CFC and HCFC groups

R12 refrigerant. Difluorodichloromethane is related to CFC group. It is characterized by high ozone depletion potential (ODP = 1) and big global warming potential (GWP = 8500). Clear gas with specific smell, 4.18 times as heavy as the air. Characteristics on the saturation line are given in Appendix 1. One of the most widespread and safe in operation refrigerants. Under its inclusion volume fraction in the air of more than 30%, asphyxiation occurs due to the lack of oxygen. R12 tolerance concentration (TC), in particular under two hours of exposure, corresponds to its inclusion volume fraction of 38,5...30,4 %. Non-explosive, but under t > 330 ^oC is decomposed with formation of hydrogen chloride, anhydrous hydrogen fluoride and trails of poisonous gas - phosgene. It is unrestrictedly resolved in oil, does not carry electric current and is poorly resolved in water. Moisture volume fraction in R12 for domestic refrigerators should not exceed 0,0004%. Dehydrated R12 is neutral to all the metals. It is characterized by high fluidity, which facilitates its penetration through the smallest looseness and even through pores of commercial iron. At the same time, thanks to R12 high fluidity, refrigerative oils penetrate through all rubbing parts and reduce their wear-out. Since R12 is a good dissolvent of many organic substances, during manufacturing of pads they use special rubber - sevanite or paronite. In refrigerating equipment, R12 was widely used to obtain average temperatures.

R11 refrigerant. Fluorotrichloromethane, heavy gas (4,74 as heavy as the air), related to CFC group. It is characterized by high ozone-depleting activity (ODP = 1). According to the Montreal Protocol, since January 1, 1996, there has been stopped R11 production (Copenhagen,1992y.). For human body, R11 is harmless, it is non-explosive, unrestrictedly resolved in the mineral oils. R11 is insoluble in water, permissible mass moisture proportion is not more than 0,0025%. Dehydrated refrigerant is neutral to all the metals, except alloys, containing more that 20% of magnesium. Normal boiling temperature is 23,8 ^oC. Volumetric refrigerating effect of R11 is low; it is used in refrigerating machines under boiling temperature up to -20 ^oC. R11 characteristics on the saturation line are given in Appendix 2. R11 refrigerant was widely used in industrial air conditioners, turbine compressors of average and high power.

R502 refrigerant. Azeotrope blend of R22 and R115 refrigerants. R22 mass proportion constitutes 48,8%, and R115 - 51,2%. It is related to CFC group, has the following ecological characteristics: ODP = 0,33; GWP = 4300. Non-explosive, low-toxic and chemically inert to metals. R502 resolvability in oils, heat transfer coefficient during boiling and condensation are close to the corresponding values for R22. Peculiar feature: R502 is poorly soluble in water. Tolerance concentration of R502 in the air constitutes 3000 mg/m³. Its volumetric refrigerating effect is higher and discharge temperature is approximately 20 ^oC lower that those of R22, which positively manifests itself on the temperature of electric motor winding during operation of hermetic refrigeration compressor. R502 refrigerant was used in low-temperature compression refrigerating facilities. Characteristics of R502 refrigerant on the saturation line are given in Appendix 3.

R22 refrigerant. Difluorochloromethane is related to HCFC group. It has low ozone depletion potential (ODP = 0,05), not high global warming potential (GWP = 1700), that is, ecological substances of R22 are much better than those of R12 and R502. This clear gas with weak smell of chloroform is more poisonous than R12, non-explosive and incombustible. Characteristics of R22 refrigerant on the saturation line and its physical qualities are given in Appendices 4, 18. Compared to R12, R22 refrigerant is worse soluble in oil, but it easily penetrates through looseness and neutral to metals. Refrigerating industry produces refrigerating oils of high quality for R22. Under temperature higher than 330 ^oC, R22 is decomposed at the presence of metals, thus, forming the same substances as R12. R22 refrigerant is poorly soluble in water, moisture volume fraction in it should not exceed 0,0025%. Heat transfer coefficient during boiling and condensation is 25...30% higher than that of R12; however, R22 has higher condensation pressure and discharge temperature (in refrigerating machines). R22 tolerance concentration in the air is 3000 mg/m³ under exposure of 1 hour. This refrigerant is widely used to obtain low temperatures in compression refrigerating facilities, in the conditioning systems and heat pumps. In refrigerating facilities, operating on R22, it is necessary to use mineral or alkyl benzene oils. You cannot mix R22 with R12 - azeotrope blend will be formed.

As to power effectiveness, R502 and R22 are relatively close. Refrigerating facility using R502 as an actuating fluid can be adapted to use R22. However, as it was stated above, R22 has higher pressure of saturated vapors, and consequently, higher discharge temperature.

Ranges of R22 refrigerant use in refrigerating systems are given on Figure.

R123 refrigerant. It is related to HCFC group. Boiling point under atmosphere conditions is 27,9 ^oC. Ozone depletion potential ODP = 0,02, global warming potential GWP = 90. Molecular mass is 152,9. Characteristics of R123 refrigerant on the saturation line and its physical qualities are given in Appendices 5 and 17. The refrigerant is intended for retrophite (substitution of the refrigerant for ozone-safe one) of refrigerating facilities - water-coolants operating on R11. Theoretical refrigerating effect of the cycle with R123 constitutes 0,86 relatively to refrigerating effect of the cycle with R11, condensation temperature and pressure are 10...15% lower compared to R11. In combination with R123, it is recommended to use alkyl benzene refrigerating oil or the blend of mineral with alkyl benzene.