History of creation

Since the midst of 18th and till the beginning of 20th centuries there have been used different substances as refrigerants for refrigerating systems: water, diethyl and methyl ethers, ammonia, carbon dioxide, sulphur anhydride, methyl chloride, etc. Water became the first refrigerant - in 1755 it was used this way in the laboratory facility created by William Hallen. Later, in 1834, Jacob Perkins manufactured a compression machine operating on diethyl ether, and in 1844 John Gorrie manufactured an air-compression- and- extension machine. In 1859 Ferdinand Karrer created an absorption refrigerating machine operating on ammonia, and four years later Charles Teller tested a compressor operating on methyl ether.

Due to active promotion of serial production of domestic refrigerators in the USA, sulphur anhydride and ammonia have been widely used as refrigerants till the end of the 20th century. After output of the first batches of dichloride fluoromethane related to the group of chlorofluorocarbons (CFC) by the company "Kinetic Chemicals Inc" (USA) and organization of its industrial production in 1932, many working substances, except ammonia, almost completely disappeared from the market of refrigerants. The same company introduced the commercial name of freon-12. Designation of the refrigerant with the letter R, as well as denomination of freon, became generally accepted.

In the midst of thirties there was adjusted production of R11, R113 and R114 refrigerants on an industrial scale. R11 refrigerant was further used in the air-conditioning systems. Since 1935 there has been organized production of R22 refrigerant related to the group of hydro chlorofluorocarbons (HCFC). R22 was used in low-temperature refrigerating systems. In 1952 there was derived R502 refrigerant substituting R22 in low-temperature refrigerating facilities, which allowed reducing discharge temperature characteristic for R22 in compressors. In order to obtain very low temperatures, there have been derived R13, R503 and R13B1 refrigerants.

Starting from the sixties, R22 and R502 refrigerants have become one of the main refrigerants in industrial and commercial mid- and low-temperature refrigerating facilities, conditioners and heat pumps.

Before the beginning of the eighties, CFC and HCFC took the leading stand in refrigerating industry (domestic, commercial and industrial refrigerating equipment). They were viewed as the substances possessing only advantages compared with other refrigerants.

Out of all refrigerants suggested before, only ammonia (R717) with its highest thermodynamic and technical-operational figures within the wide temperature range, compared with refrigerants of CFC and HCFC groups, is being widely used at present in industrial refrigerating systems, heat pumps, absorption conditioners and domestic absorption refrigerators.

However, by the eighties, when specialists of a number of countries started to consider the problems of CFC and HCFC influence on the environment, these refrigerants have become the matter of concern due to existing global problems: rising of greenhouse effect and possible destruction of ozone layer.

Greenhouse effect rises due to the fact that some gases of the Earth's atmosphere keep back infrared irradiation emitted by the earth surface. The phenomenon of greenhouse effect allows keeping such temperature on the surface of the Earth, which makes life initiation and development possible. If there were no greenhouse effect, the average temperature of the earth would be about 20 K lower than it is now.

Restraint of infrared irradiation in nature occurs due to water vapour contented in air and clouds. However, other gases, which are humanity activities products, in particular, carbon dioxide and refrigerants of CFC category, also prevent this irradiation from emitting. Due to the fact that carbon dioxide and CFC (included) being present in the atmosphere increases effectiveness of restraint of the earth infrared irradiation compared with natural effectiveness, the average temperature of the earth surface increases more than necessary, thus giving rise to artificial greenhouse effect added to the natural one. Though concentration of all CFC as a whole is much lower in the atmosphere than concentration of carbon dioxide, their effectiveness as to restraint of infrared irradiation is thousands times as higher as the effectiveness of carbon dioxide, in particular, due to their very long life period (60 years for R11, 120 years for R12 and 250 years for R115 being a composite of R502).

Destruction of stratosphere ozone is quite another phenomenon because it is connected with ultra-violet irradiation of the Sun. The atmosphere layer being the remotest one from the Earth is stratosphere which is the spherical layer of approximately 35 km thick starting from the height of 15 and ending on the height of 50 km from the Earth surface. In this layer there is ozone absorbing 90% of ultra-violet irradiation of the Sun and functioning as a safety screen for the earth life.

American scientists Mario Molina and Shepwood Rowland from California University (USA) were the first to describe the mechanism of exhaustion of the Earth protection layer in 1974. They showed that a molecule of chlorine oxide and an atom of chlorine are very strong catalytic agents facilitating ozone destruction. The travel of chlorine molecules to stratosphere takes one-two years. Only chemically stable molecules, which are not destroyed under exposure to sun rays, chemical reactions, and do not dissolve in water, can reach stratosphere. CFC molecules possess these same qualities. Their life period is more than 100 years. CFC molecules are heavier than air, and their number in stratosphere is extremely low: three-five CFC molecules for 10 billion of air molecules. Under exposure to ultra-violet irradiation, a chlorine atom is detached from CFC molecules, and the remaining residue is easily oxidized, thus creating a chlorine oxide molecule and a new residue. The chlorine atom and chlorine oxide molecule are actively engaged into the catalytic cycle of ozone destruction. One chlorine molecule reaching the atmosphere is able to destroy (10:100) thousand of ozone molecules.

By the midst of the seventies, the output of freons has reached considerable figures. In particular, by 1976 the output of R12 has reached almost 340 thousand tons and 27 thousand tons of them were intended for refrigerating systems. In 1986 overall production of freons amounted 1.123 million tons (30% fell to the share of the USA, 20% - of Europe, 10 % - of Russia and Japan each).

The problem of control of output and input of ozone-destroying CFC and HCFC was put forth on an international scale by the Vienna Convention on Protection of Ozone Layer in 1985. The further important step in solution of this problem became Montreal Protocol having been signed by all industrial countries in 1987.

With the aim of R12 substitution, since the beginning of the nineties main world producers of chemical products have developed and produced one-component ozone-safe R134a refrigerant and alternative service (interstage) blends (R401A, etc.). In order to substitute R502 and R22, there have been created service blends related to HCFC group (R402A, etc.), and ozone-safe blends of CFC group (R407C, etc.). However, by now neither of well-known or recently synthesized individual refrigerants possesses in full measure the complex of characteristics peculiar to dangerous refrigerants.

Prohibition on R12 output and input resulted in increase of R22 world selling: in particular, in 1994 it amounted 207 515 tons. And though CFC have been substantially displaced from domestic refrigerating equipment, transport refrigerating facilities, commercial refrigerating equipment, industrial conditioners, by now in the countries of European Union up to 110 thousand tons of CFC are still used in operating refrigerating equipment. During the recent years refrigerating industry has been actively looking for substitution of HCFC group refrigerants. This question is especially sharp in the USA where HCFC are used in the majority of centralized conditioning systems and heat pumps, as well as in many refrigerating systems. In the USA almost 80% of new houses designed for one family are equipped with the centralized conditioning system operating on HCFC.

Resolutions of the Convention on reduction of greenhouse gas emission taken in Kyoto (Japan) in 1997 complicated selection of a long-term alternative to R22 even more.

In order to investigate and develop alternative refrigerants being able to substitute R22 refrigerant (HCFC), there has been organized Alternative Refrigerants Evaluation Program - AREP. 40 biggest companies from all over the world participate in this program.

A number of states invested considerable financial means into development of alternative refrigerants, and these financial means amounted, according to evaluation of specialists, more than 2.4 billion dollars for the last six years. Only the expenses on investigation of R134a toxicity amounted 4.5 million dollars, with the duration of investigation of 7 years, according to International Institute of Cold.

Alternative zoetrope service blends of middle pressure and high pressure and blend refrigerants of CFC group have a number of peculiarities to keep in mind while refrigerating equipment designing and operation. It is the temperature "glide" (difference of transformation point at constant pressure); change of blend composition in case of leakage of one of the components. In particular, at slow leakage of a refrigerant more volatile components boil and leak first while less volatile components remain, and this can change characteristics of an original composition refrigerant. One more problem is immiscibility of a number of refrigerants with mineral oils resulting in necessity to substitute them for expensive polyester hygroscopic oils.

In the suggested reference manual the authors have made an attempt to collect necessary information as to traditional and alternative refrigerants being used in operating refrigerating facilities in the area of moderately low temperatures. There have been considered in detail alternative one-component refrigerants and service blends of HCFC, CFC groups for refrigerating systems and air-conditioning systems, refrigerating transport; their compatibility with refrigerating oils, metals, plastics and elastomers. There have been given recommendations as to use of different types of refrigerating oils with alternative refrigerants.

Reservoirs for storage and transportation of alternative refrigerants have been considered. Necessary information as to measures on prevention of refrigerant leakage is given.

Considerable attention is focused on servicing of refrigerating systems, in particular, there have been analyzed in detail operations on substitution of R12 refrigerant for R134a, R401A, 409A, R401B; R500 for R401B; R502 for R404A, R507, R408A, R402B; R22 for R407C and other refrigerants.

There have been considered in detail technical means for servicing of refrigerating systems, as well as safety rules while dealing with alternative refrigerants, and there has been shown their influence on human body.

Physical characteristics of a number of traditional and alternative refrigerants are given.

Reference manual on this site will help designers and specialists on installation and after-sales service of refrigerating systems and air-conditioning systems to make right choice as to alternative refrigerants with account of their characteristics and peculiarities in different conditions of operation of refrigerating equipment in order to ensure its reliability in the process of operation and creation of the required cold-productivity with minimal power imputs.