What are refrigerants? These are special liquids. They are used in air conditioners and refrigerators. The refrigerant undergoes phase changes from liquid to gas when it absorbs heat and back to liquid when the compressor compresses the gas. The selection of the ideal refrigerant is based on thermodynamic properties. It must be non-corrosive, safe, non-toxic and non-flammable.
A Brief History of Refrigerants
Belgian scientist Frederic Sworths pioneered the synthesis of CFCs in the late 1890s. His discovery occurred after the replacement of chloride in carbon tetrachloride by futuride for the synthesis of CFC-11 and CFC-12. In the late 1920s, Thomas Midgley Jr. improved the synthesis process and challenged the use of CFCs as a refrigerant to replace the ammonia, chloromethane and sulfur dioxide that were commonly used at the time.
They were harmful, flammable, and some even toxic. The most commonthe refrigerant was a CFC called Freon - DuPont's brand name for the "R-12" refrigerator. According to the requirements of the 30s of the last century, these refrigerants seemed to be ideal, scientifically based and safer, non-corrosive gases and cheap to manufacture.
It wasn't until the 1970s that chlorine molecules were found to completely destroy the ozone layer and were banned. In the 1970s, scientists discovered that the refrigerant ammonia interfered with the penetration of infrared rays into them, as they accumulate in the atmosphere and cause heat transfer, which leads to climate change, so this compound was banned.
In the 1990s and 2000s, CFCs were replaced by HCFCs (hydrochlorofluorocarbons) and the most common HCFC is "R-22" which had much less devastating effects on ozone, however it was still dangerous. To solve the problem of ozone depletion, scientists came up with HFCs that did not contain chlorine. However, they later realized that HFC is still damaging the environment through greenhouse gases.
Modern types of refrigeration media
The European Commission has mandated that R134A refrigerant not be used for certified passenger cars sold in the European Union. This mandate was originally intended for 1 January 2011. However, since the new refrigerant was not yet available to the general market, this deadline was extended to January 1, 2013.
Starting from January 2017, all newly registeredvehicles were required to use an alternative refrigerant. In 2018, only 60% of new European-made passenger cars use a safe refrigerant. Vehicles sold outside the European Union continue to use R134A or an even more dangerous refrigerant.
Main types of refrigerants:
- CFCs - chlorofluorocarbons.
- HCFC – HydroChloroFluoroCarbons.
- HFC – HydroFluoroCarbons.
However, they have all been or will be replaced in the near future due to environmental impacts. HFO refrigerant is now beginning to replace CFCs as they have much lower global warming potentials and do not deplete ozone, although some are highly flammable. Currently, the 4th generation of refrigerants is entering the market, which have great thermodynamic properties and are environmentally friendly.
Choosing an alternative for R12
R12 refrigerant is still widely used in refrigeration applications. Indeed, it was very difficult to find one that could replace this universal refrigerant in operating conditions. R134A is the most suitable for these purposes.
Comparison of R134A and R12:
- The capacity at -7°C evaporator temperature is the same for both refrigerants, and below -7°C, if R12 is replaced with r134A refrigerant, there will be a significant loss of cooling effect. In such cases it is recommended to use mixtures of refrigerants instead of replacing R134A. Freon 134 can also be used for low temperaturesituations.
- The heat transfer coefficients for R134A are higher than R12. If they exist in the same liquid phase, the heat transfer coefficient of the R134A refrigerant is 27–37% higher, and in the gas phase it is 37–45% higher. If they exist in two phases, liquid and gaseous, the heat transfer coefficient for R134A is 28% to 34% higher in the evaporator and 35 to 41% higher in the condenser.
- The cooling effect of R134A is about 22% greater than that of R12. Thus, the mass flow rate of R134A required per ton of refrigeration is about 18% less than R12. This means that for a given capacity of the refrigeration system, the required amount of it is 18% less than when using R12. That is, in all equipment where R12 is replaced by freon 134, the amount of refrigerant that should be charged is less than R12. However, the specific volume of R134A is slightly larger than R12, so for the same amount of refrigerant, the volume occupied by R134A is larger than R12.
- The increase in the cooling effect of R134A is offset by an increase in its specific volume. Thus, R134a charged in modified systems should be 5–10% less than R12.
Convert R12 to R134A
Some early installations used ammonia as a refrigerant. However, most modern cars built before 1995 used the R12. R12 was a technologically advanced and efficient ic2 refrigerant, however it was later discovered to be an ozone depleting gas and its production and use was restricted.
After 1995, it was replaced by the R134A, and it is stillused in many cars. If the household has an old car with an R12 air conditioning system, then motorists experience great problems with replenishing such a system in case of leaks or maintenance. The industry began producing special adapters, after which the process of converting the system to R134A became simple.
Changes to the cooling system
To convert R12 to R134A, only a few small changes to the system need to be made. Luckily, the compressor used in the old R12 system will still work with R134A refrigerant and will be just as efficient. The condenser and evaporator are just heat exchangers, so they also do not need to be changed to run another refrigerant.
One of the components that needs to be changed is the dryer. The last element of the system that will need to be changed are the pressure ports. The R134A uses different ports for system charging and pressure measurement, so the old R12 ports need to be removed and replaced or supplemented with adapters. After purchasing the necessary equipment, remove the old refrigerant and oil. When installing a new ic2 refrigerant, R134A compatible PAG oil must also be added to keep the compressor lubricated.
After converting a system from R12 to R134A, it is important to check the system pressure for a few days to make sure everything is working properly. If any small leaks were noticed in the system, apply Red Angel A/C Stop Leak to sealsystem.
Refrigerants are safer than freon
Common HCFC R-22, which has been in use for decades, is not as good for the environment as experts once thought. The Environmental Protection Agency worked to phase out the refrigerant and eventually banned it entirely. The phase out of R-22 began in 2010. By 2020, the use of the refrigerant will be severely restricted, and completely banned by 2030.
The most environmentally friendly refrigerants currently available on the market are "R-290" and "R-600A". They are HCs, or hydrocarbons, and their chemical names are "Propane" for R-290 and "Isobutane" for R-600A. They are 100% halogen free, have no ozone depletion potential and are the least hazardous in terms of potential global warming. They are also highly energy efficient, but highly flammable as they are hydrocarbons. Currently, the most "green" types of refrigerants are R134A, R-407C, R-410A. The manufacturers who produce these refrigerants claim that the substances are absolutely safe.
Cylinder with freon R134A
With the discovery of the damaging effects of CFC and HCFC refrigerants on the ozone layer, this group has been widely used as a replacement. The refrigerant in the R134A refrigerator is hydrofluorocarbon (HFC), which has zero ozone depletion potential and little to no greenhouse effect.
Refrigerant R134Ais a chemical compound tetrafluoroethane, consisting of two carbon atoms, two hydrogen atoms and four fluorine atoms. Its chemical formula is CF3CH2F. The molecular weight of R134A refrigerant is 133.4 and its boiling point is 26.1°C. R134A is non-flammable and non-explosive, has normal toxicity and good chemical stability, somewhat high affinity for moisture.
R134A is very similar to R12 in general physical and thermodynamic properties. Therefore, it is considered an excellent replacement. The properties of R134 refrigerants are as follows:
- Auto ignition temperature - 770 °C.
- Ozone depletion rate - 04.
- Solubility in water 0.11 wt% 25 C.
- Critical temperature - 122 °C.
- Color code: light blue.
- Global Warming Potential (GWP)1200.
- Refrigerant temperature, boiling point -26.1 °C.
Thermodynamic properties of R-407C
In terms of its properties, it corresponds to the characteristics available in R-22. R-407C is a common refrigerant replacement for those looking to upgrade R-22 equipment. The mixture of hydrofluorocarbons includes pentafluoroethane, difluoromethane and 1, 1, 1, 2-tetrafluoroethane. A widely used alternative refrigerant popular in packaged air conditioners and brushless separation systems, as well as light air conditioning and direct expansion systems found in residential, commercial and industrial applications. R-407C also works in medium temperature refrigeration systems and in manynew appliances.
New equipment using nitrogen as a holding charge works best with R-407C due to the use of polyol essential oil. While new appliances and refrigeration systems are most common, R-407C can be upgraded on some R-22 systems if an oil change is included in the procedure. This alternative to Freon is considered environmentally friendly due to its zero ozone depletion potential.
Ozone Depletion Potential R-404A
It is 0 in this refrigerant, just like R-407C and R-134A. It is often used for refrigeration systems that require -45°C to 15°C. It is most useful in commercial and industrial transportation applications due to its wide operating temperature range. It is very similar to the R-22 and offers better performance. Because R-404A does not react quickly to air or water, it is considered safe for many uses. It is also non-flammable, colorless and odorless.
However, as with any refrigerant, users should always take appropriate precautions to protect themselves. Direct contact with R-404A can still cause frostbite, and excessive exposure to fire or heat can cause the reservoir to rupture. R-404A is fairly common and available for purchase at stores that specialize in providing heating and cooling products.
A mixture of two hydrofluorocarbon refrigerants, difluoromethane and pentafluoroethane, isA neozone depleting refrigerant that provides better energy efficiency than R-22 and R-407C and does not use chlorine in its formulation. It is considered more suitable as a replacement for R-22 due to its higher pressure and cooling capacity.
Feature R-410A
If users decide to purchase devices that use R-410A, the process is usually quite simple. In fact, many air conditioner and refrigeration companies make units specifically for use with R-410A. Although it is most popular in commercial refrigeration, air conditioners and refrigerators, it is important to note that this Freon alternative will not work in A/CR-22 units.
R-410A refrigerants have a higher pressure rating, so a different manifold gauge is required than that normally used with R-22. The refrigerant must be charged in liquid form and only in short bursts. R-410A is sold under several brand names: AZ-20, Suva410A, GenetronR410A, Forane410A, EcoFluo rR410 and Puron. It is quite easy to buy online and in speci alty stores.
Vehicle air conditioning
A 2006 EU directive requires all new vehicles sold in the EU to be equipped with low global warming potential (GWP) refrigerants. The limit is set to GWP 150 which YF can currently provide. Its advantage is the property of self-disposal - it completely decomposes in the atmosphere in abouteleven days.
Despite the fact that HFO1234yf was accepted as a new refrigerant, Germany had doubts. Daimler and some other German manufacturers and also regulatory authorities believe that YF is dangerous due to its high flammability. In response, Germany approved some Daimler vehicles to continue running on R134A, contrary to the EU directive.
The European Commission has even threatened legal action against Germany for failing to fully implement new refrigerant emission regulations. GM and Toyota have publicly expressed their support for YF and stated that they consider the substance to be safe.
Cost of new systems
Additional cost of new YF refrigerant is in the range of EUR30-50. YF systems are less efficient and require the additional use of an internal heat exchanger.
Because the manufacturing process cost for YF is higher than R134A, a feed-in tariff is expected on this product for many years, especially from 2018 when all newly registered vehicles in the European Union will be required to use a refrigerant other than R134A. from R134A.
Price increase from February 1, 2018:
- R452a + 20%.
- R410a + 20%.
- R448a + 15%.
- R449a + 15%.
Modernization of the R-22 system
Replacing R22 with R134A is a fairly simple process. First of all, the full R22 should be removed from the system. Then it is necessary to remove all lubricating oil from the system(the maximum amount of oil remaining inside the system is 5% of the total amount present in it). Mineral oil should be replaced with synthetic ester oil. The dryer and oil filter should also be replaced.
The amount of R134A required in the system is 90 to 95% R22. Labels should be placed on systems that have been upgraded with R134A describing the new refrigerant and lubricating oil. Although the process is easy, it is important to do it carefully. Residues of R-22 in the system can lead to cross-contamination. It for R-22 and R-134A can make the car's cooling system less reliable and raise the compressor head pressure to dangerous levels, leading to a complete system failure. In addition, R-134A requires a special oil blend - polyarylene.
In 1987, the Montreal Protocol was announced, which is an international treaty in many countries to help combat the damaged layer of the O-zone. One of his initiatives was to phase out CFCs worldwide. In 1994, the US ended the use of R-12 in the automotive industry. R-12 has been replaced by the HFC alternative R-134a. In 2010, under the Montreal Protocol, the US announced that it would phase out the use of R-22 in future applications. All new machines will target HFC R-410A, which does not contain chlorine.
