Product Code Database
A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and Heat pump, where they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated because of their toxicity and flammability, as well as the contribution of CFC and HCFC refrigerants to ozone depletion and the contribution of HFC refrigerants to climate change.
Refrigerants are used in a direct expansion (DX) circulating system to transfer energy from one environment to another, typically from inside a building to outside or vice versa. These can be air conditioner cooling only systems, cooling & heating reverse DX systems, or heat pump and heating only DX cycles. Refrigerants can carry 10 times more energy per kg than water, and 50 times more than air.
Refrigerants are controlled substances that are classified by several international safety regulations and, depending on their classification, may only be handled by qualified engineers due to extreme pressure, temperature, flammability, and toxicity.
In 1928 Thomas Midgley Jr. created the first non-flammable, non-toxic chlorofluorocarbon gas, Freon (R-12). The name is a trademark name owned by DuPont (now Chemours) for any chlorofluorocarbon (CFC), HCFC (HCFC), or hydrofluorocarbon (HFC) refrigerant. Following the discovery of better synthesis methods, CFCs such as R-11, R-12, https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/download/3297/1244/ R-123 and R-502 dominated the market.
Hydrofluorocarbons (HFCs) such as R-134a, R-407A, R-407C, R-404A, R-410A (a 50/50 blend of R-125/Difluoromethane) and R-507 were promoted as replacements for CFCs and HCFCs in the 1990s and 2000s. HFCs were not ozone-depleting but did have global warming potentials (GWPs) thousands of times greater than CO2 with atmospheric lifetimes that can extend for decades. This in turn, starting from the 2010s, led to the adoption in new equipment of Hydrocarbon and HFO (hydrofluoroolefin) refrigerants R-32, R-290, R-600a, R-454B, R-1234yf, R-514A, R-744 (), R-1234ze(E) and R-1233zd(E), which have both an ODP of zero and a lower GWP. Hydrocarbons and are sometimes called natural refrigerants because they can be found in nature.
The environmental organization Greenpeace provided funding to a former East German refrigerator company to research alternative ozone- and climate-safe refrigerants in 1992. The company developed a hydrocarbon mixture of propane and isobutane, or pure isobutane, called "Greenfreeze", but as a condition of the contract with Greenpeace could not patent the technology, which led to widespread adoption by other firms. Policy and political influence by corporate executives resisted change however,Benedick, Richard Elliot Ozone Diplomacy Cambridge, MA: Harvard University 1991. citing the flammability and explosive properties of the refrigerants, and DuPont together with other companies blocked them in the U.S. with the U.S. EPA.
Beginning on 14 November 1994, the U.S. Environmental Protection Agency restricted the sale, possession and use of refrigerants to only licensed technicians, per rules under sections 608 and 609 of the Clean Air Act. In 1995, Germany made CFC refrigerators illegal.
In 1996 Eurammon, a European non-profit initiative for natural refrigerants, was established and comprises European companies, institutions, and industry experts.
In 1997, FCs and HFCs were included in the Kyoto Protocol to the Framework Convention on Climate Change.
In 2000 in the UK, the Ozone Regulations came into force which banned the use of ozone-depleting HCFC refrigerants such as R22 in new systems. The Regulation banned the use of R22 as a "top-up" fluid for maintenance from 2010 for virgin fluid and from 2015 for recycled fluid.
In 2006, the EU adopted a Regulation on fluorinated greenhouse gases (FCs and HFCs) to encourage to transition to natural refrigerants (such as hydrocarbons). It was reported in 2010 that some refrigerants are being used as recreational drugs, leading to an extremely dangerous phenomenon known as inhalant abuse.Harris, Catharine. "Anti-inhalant Abuse Campaign Targets Building Codes: 'Huffing’ of Air Conditioning Refrigerant a Dangerous Risk." The Nation'
From 2011 the European Union started to phase out refrigerants with a global warming potential (GWP) of more than 150 in automotive air conditioning (GWP = 100-year warming potential of one kilogram of a gas relative to one kilogram of CO2) such as the refrigerant HFC-134a (known as R-134a in North America) which has a GWP of 1526. In the same year the EPA decided in favour of the ozone- and climate-safe refrigerant for U.S. manufacture.
A 2018 study by the nonprofit organization "Drawdown" put proper refrigerant management and disposal at the very top of the list of climate impact solutions, with an impact equivalent to eliminating over 17 years of US carbon dioxide emissions.
In 2019 it was estimated that CFCs, HCFCs, and HFCs were responsible for about 10% of direct radiative forcing from all long-lived anthropogenic greenhouse gases. and in the same year the UNEP published new voluntary guidelines, however many countries have not yet ratified the Kigali Amendment.
From early 2020 HFCs (including R-404A, R-134a, and R-410A) are being superseded: Residential air-conditioning systems and heat pumps are increasingly using Difluoromethane. This still has a GWP of more than 600. Progressive devices use refrigerants with almost no climate impact, namely R-290 (propane), R-600a (isobutane), or R-1234yf (less flammable, in cars). In commercial refrigeration also (R-744) can be used.
The ideal refrigerant would be: corrosive, toxicity, flammability, with no ozone depletion and global warming potential. It should preferably be natural with well-studied and low environmental impact. Newer refrigerants address the issue of the damage that CFCs caused to the ozone layer and the contribution that HCFCs make to climate change, but some do raise issues relating to toxicity and/or flammability.
With the exception of isobutane and propane (R600a, R441A, and R290), ammonia and CO2 under Section 608 of the United States' Clean Air Act it is illegal to knowingly release any refrigerants into the atmosphere.
Refrigerant reclamation is the act of processing used refrigerant gas that has previously been used in some type of refrigeration loop such that it meets specifications for new refrigerant gas. In the United States, the Clean Air Act of 1990 requires that used refrigerant be processed by a certified reclaimer, which must be licensed by the United States Environmental Protection Agency (EPA), and the material must be recovered and delivered to the reclaimer by EPA-certified technicians.
R-X1X2X3X4
For example, R-134a has 2 carbon atoms, 2 hydrogen atoms, and 4 fluorine atoms, an empirical formula of tetrafluoroethane. The "a" suffix indicates that the isomer is unbalanced by one atom, giving 1,1,1,2-Tetrafluoroethane. R-134 (without the "a" suffix) would have a molecular structure of 1,1,2,2-Tetrafluoroethane.
The same numbers are used with an R- prefix for generic refrigerants, with a "Propellant" prefix (e.g., "Propellant 12") for the same chemical used as a propellant for an aerosol spray, and with trade names for the compounds, such as " Freon 12". Recently, a practice of using abbreviations HFC- for hydrofluorocarbons, CFC- for chlorofluorocarbons, and HCFC- for hydrochlorofluorocarbons has arisen, because of the regulatory differences among these groups.
ASHRAE Standard 34, Designation and Safety Classification of Refrigerants, assigns safety classifications to refrigerants based upon toxicity and flammability. ASHRAE assigns a capital letter to indicate toxicity and a number to indicate flammability. The letter "A" is the least toxic and the number 1 is the least flammable.
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Requirements and desirable properties
A refrigerant needs to have: a boiling point that is somewhat below the target temperature (although boiling point can be adjusted by adjusting the pressure appropriately), a high heat of vaporization, a moderate density in liquid form, a relatively high density in gaseous form (which can also be adjusted by setting pressure appropriately), and a high critical temperature. Working pressures should ideally be containable by copper tubing, a commonly available material. Extremely high pressures should be avoided.
Common refrigerants
Refrigerants with very low climate impact
With increasing regulations, refrigerants with a very low global warming potential are expected to play a dominant role in the 21st century, in particular, R-290 and R-1234yf. Starting from almost no market share in 2018, low GWPO devices are gaining market share in 2022.
R-290 C3H8 Propane 3.3 Increasing use Low cost, widely available, and efficient. They also have zero ozone depletion potential. Despite their flammability, they are increasingly used in domestic refrigerators and heat pumps. In 2010, about one-third of all household refrigerators and freezers manufactured globally used isobutane or an isobutane/propane blend, and this was expected to increase to 75% by 2020. See R-290. Commonly used before the popularisation of CFCs, it is again being considered but does suffer from the disadvantage of toxicity, and it requires corrosion-resistant components, which restricts its domestic and small-scale use. Anhydrous ammonia is widely used in industrial refrigeration applications and hockey rinks because of its high energy efficiency and low cost. Less performance but also less flammable than R-290. GM announced that it would start using "hydro-fluoro olefin", HFO-1234yf, in all of its brands by 2013. GM to Introduce HFO-1234yf AC Refrigerant in 2013 US Models Was used as a refrigerant prior to the discovery of CFCs (this was also the case for propane) and now having a renaissance due to it being non-ozone depleting, non-toxic and non-flammable. It may become the working fluid of choice to replace current HFCs in cars, supermarkets, and . Coca-Cola has fielded CO2-based beverage coolers and the U.S. Army is considering CO2 refrigeration. Due to the need to operate at pressures of up to , CO2 systems require highly resistant components, however these have already been developed for mass production in many sectors.
Most used
Promoted as climate-friendly substitute for R-134a and R-410A, but still with high climate impact. Has excellent heat transfer and pressure drop performance, both in condensation and vaporisation. It has an atmospheric lifetime of nearly 5 years.May 2010 TEAP XXI/9 Task Force Report Currently used in residential and commercial air conditioning and . R-134a HFC-134a CH2FCF3 1,1,1,2-Tetrafluoroethane 3790 1550 Widely used Most used in 2020 for hydronic heat pumps in Europe and the United States in spite of high GWP. Commonly used in automotive air conditioners prior to phase out which began in 2012. Most used in split heat pumps / AC by 2018. Almost 100% share in the USA. Being phased out in the US starting in 2022.
Banned / Phased out
Production was banned in developed countries by Montreal Protocol in 1996 Also known as Freon, a widely used chlorofluorocarbon halomethane (CFC). Production was banned in developed countries by Montreal Protocol in 1996, and in developing countries (Article 5 countries) in 2010. A widely used hydrochlorofluorocarbon (HCFC) and powerful greenhouse gas with a GWP equal to 1810. Worldwide production of R-22 in 2008 was about 800Gg per year, up from about 450Gg per year in 1998. R-438A (MO-99) is a R-22 replacement.[2] Chemours M099 as R22 Replacement R-123 HCFC-123 CHCl2CF3 2,2-Dichloro-1,1,1-trifluoroethane 292 79 US phase-out Retrieved Dec. 18, 2021 R-123 refrigerant was used to retrofit some chiller that used R-11 refrigerant Trichlorofluoromethane. The production of R-11 was banned in developed countries by Montreal Protocol in 1996.[4] Refrigerant R11 (R-11), Freon 11 (Freon R-11) Properties & Replacement
Other
R-152a HFC-152a CH3CHF2 1,1-Difluoroethane 506 138 As a compressed air duster R-407C Mixture of difluoromethane and pentafluoroethane and 1,1,1,2-tetrafluoroethane A mixture of R-32, R-125, and R-134a R-454B Difluoromethane and 2,3,3,3-Tetrafluoropropene [8] Johnson Controls selects R-454B as future refrigerant for new HVAC equipment >27 May 2021 page 30, column 1, paragraph 2 R-514A HFO-1336mzz-Z/trans-1,2- dichloroethylene (t-DCE) [10] Opteon™ XP30 (R-514A) refrigerant[11] Trane adopts new low GWP refrigerant R514A >15 June 2016
Refrigerant reclamation and disposal
Coolant and refrigerants are found throughout the industrialized world, in homes, offices, and factories, in devices such as refrigerators, air conditioners, central air conditioning systems (HVAC), freezers, and dehumidifiers. When these units are serviced, there is a risk that refrigerant gas will be vented into the atmosphere either accidentally or intentionally, hence the creation of technician training and certification programs in order to ensure that the material is conserved and managed safely. Mistreatment of these gases has been shown to deplete the ozone layer and is suspected to contribute to global warming.
Classification of refrigerants
Refrigerants may be divided into three classes according to their manner of absorption or extraction of heat from the substances to be refrigerated:
R numbering system
The R- numbering system was developed by DuPont (which owned the Freon trademark), and systematically identifies the molecular structure of refrigerants made with a single halogenated hydrocarbon. ASHRAE has since set guidelines for the numbering system as follows:
Series
Ethane Derived Chains
Propane Derived Chains
Propene derivatives
Blends
Miscellaneous
Refrigerant safety
Refrigerants are classified under regulations such as ISO 817/5149, AHRAE 34/15, & BS EN 378. The Pressure of these gases can range from . They can also be at temperatures as low as and as high as over . Refrigerants have varying classifications of flammability: A1 class are non-flammable, A2/A2L class are flammable, and A3 class are extremely flammable and/or explosive. Toxicity also varies; B1 class refrigerants have low toxicity, while B2 refrigerants are moderately toxic and B3 refrigerants are highly toxic. These regulations relate to situations where these refrigerants are released into the atmosphere in the event of an accidental leak, not while circulated. Due to these regulations, most refrigerants may only be handled by qualified/certified engineers for the relevant classes; in the UK, C&G 2079 is required for A1-class refrigerants, while C&G 6187-2 is required for A2, A2L, and A3-class refrigerants. Due to their non-flammability, non-explosivity, and non-toxicity, A1 class refrigerants have been used in open systems (where they are consumed when used rather than circulated) like fire extinguishers, Inhaler, computer rooms, and insulation since 1928.
See also
Sources
IPCC reports
Other
External links
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