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The first, recognized by historians of technology, room air conditioner, released in 1929 by the General Electric company, worked on ammonia. This substance is unsafe for humans, which greatly hindered the development of refrigeration technology.

The problem was solved in 1931, when a refrigerant, harmless to the human body, freon, was synthesized. Subsequently, more than four dozen different freons were synthesized, differing from each other in properties and chemical composition. R-11, R-12 turned out to be the cheapest and most effective, which suited everyone for a long time. True, in the last 15 years they have fallen out of favor due to their ozone-depleting properties.

freons

All freons are substances formed on the basis of two gases — methane CH4 and ethane — CH3-CH3. In refrigeration, methane is R-50, ethane is R-70. All other freons are obtained from methane and ethane by replacing hydrogen atoms with chlorine and fluorine atoms. For example, the well-known R-22 is obtained from methane by replacing one hydrogen atom with chlorine and two with fluorine. The chemical formula of this freon is CHF2Cl.

The physical properties of refrigerants depend on the content of three components — chlorine, fluorine and hydrogen. So, as the number of hydrogen atoms decreases, the flammability of the refrigerants decreases, and the stability increases. They can exist in the atmosphere for a long time without decomposing into parts and harming the environment. And as the number of chlorine atoms increases, the toxicity of refrigerants and their ozone-depleting potential increases.

The damage caused by freons to the ozone layer is estimated by the value of the ozone-depleting potential, which is 0 for ozone-friendly refrigerants (R-410A, R-407C, R-134a) and up to 13 for ozone-depleting (R-10, R-110). At the same time, the ozone-depleting potential of freon R-12, until recently the most widespread throughout the world, was taken as a unit. Freon R-22, whose ozone depletion potential is 0.05, was chosen as a temporary alternative to R-12.

Popular Models


Daikin
Freon Roven R410


Daikin
Coolant (freon) Honeywell Genetron R-134a


Daikin
Freon (freon) Arkema Forane 22 (R-22)

Refrigerants, freons: all models

In general, the rapid evolution of refrigerants in the last 15 years is mainly associated with environmental problems. Freons used in air conditioners and refrigerators have been named as the main culprits of the infamous ozone holes (which is highly doubtful). Whether it’s true or not, the Montreal Protocol was adopted in 1987 to limit the use of ozone-depleting substances. In particular, according to this document, manufacturers will be forced to abandon the use of R-22 freon, on which 90% of all air conditioners operate today. In most European countries, the sale of air conditioners on this freon will be discontinued already in 2002-2004. And many new models are already supplied to Europe only on ozone-friendly refrigerants — R-407C and R-410A.

refrigerant

Properties

R-22

R-410A

R-407C

Isotropy

Yes

Yes

No

Oil

mineral

polyester

polyester

Pressure at condensing temperature +43 o FROM

16 atm.

26 atm.

18 atm.

Price per kilogram USD

4.8

32.7

29.4

Unlike traditional refrigerants, R-407C and R-410A are mixtures of different freons, and therefore are less convenient to use. So, the composition of R-407C, created as an alternative to R-22, includes three freons: R-32 (23%), R-125 (25%) and R-134a (52%). Each of them is responsible for providing certain properties: the first increases productivity, the second eliminates fire, the third determines the operating pressure in the refrigerant circuit.

This mixture is not isotropic, and therefore, with any refrigerant leaks, its fractions evaporate unevenly and the optimal composition changes. Thus, when the refrigeration circuit is depressurized, the air conditioner cannot simply be topped up; Remaining refrigerant must be drained and replaced with new. This is what became the main obstacle to the spread of R-407C.

In addition, its “environmental friendliness” in practice can lead to an additional burden on the environment. Freon evacuated from air conditioners must be disposed of, and in Russia or Asian countries, no one will mess with it. He is simply pitted in the nearest gateway. And although R-407C is not dangerous for the ozone layer, it is one of the most powerful «greenhouse gases».

The R-410A refrigerant, consisting of R-32 (50%) and R-125 (50%), is conditionally isotropic. That is, in the event of a leak, the mixture practically does not change its composition, and therefore the air conditioner can simply be refueled. However, the R-410A is not without some drawbacks. Unlike R-22, which is highly soluble in ordinary mineral oil, the new refrigerants require the use of synthetic polyester oil. What does this mean in practice?

Polyester oil has one very significant drawback — it quickly absorbs moisture, while losing its properties. Moreover, during storage, transportation and refueling, it is necessary to exclude not only the ingress of dripping moisture, but also contact with moist air, from which the oil actively absorbs water. In addition, it does not dissolve any oil products and organic compounds, which become potential pollutants.

In addition, the climate equipment itself on the R-410A with the same performance is much more expensive. The reason is the higher working pressure. So at a condensation temperature of +43 C, for R-22 it is about 16 atm., And for R-410A — about 26 atm. For this reason, all components and parts of the refrigeration circuit of the air conditioner on the R-410A, including the compressor, must be more durable. This increases the consumption of copper and makes the entire system more expensive.

And finally, the ozone-friendly refrigerants themselves are several times more expensive than traditional ones. So, for a kilogram of R-410A, you will have to pay almost 7 times more than for a kilogram of the usual R-22. A little cheaper than R407C, to which a semi-industrial range of equipment is being actively transferred. There will be a 6-fold difference, and taking into account the fact that in case of any leakage it must be drained, the real cost of freon will increase by an order of magnitude. It should also be taken into account that with an increase in operating pressure, the number of leaks will inevitably increase, since the strength of soldered, and most importantly, rolled joints remains the same.

By 2002, split systems using ozone-friendly freons were introduced to the Russian market by almost all leading companies. Although the final ban on the use of air conditioners on the currently used R-22 will only come into effect in 2014.

Source: TopClimat.ru

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