Refrigerant

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A DuPont refrigerant

A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated due to their toxicity, flammability and the contribution of CFC and HCFC refrigerants to ozone depletion and that of HFC refrigerants to climate change.

History[edit]

The observed stabilization of HCFC concentrations (left graphs) and the growth of HFCs (right graphs) in earth's atmosphere.

The first air conditioners and refrigerators employed toxic or flammable gases, such as ammonia, sulfur dioxide, methyl chloride, or propane, that could result in fatal accidents when they leaked.[1]

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), hydrochlorofluorocarbon (HCFC), or hydrofluorocarbon (HFC) refrigerant. Following the discovery of better synthesis methods, CFCs such as R-11,[2] R-12,[3] R-123[2] and R-502[4] dominated the market.

Phase out of CFCs[edit]

In the early 1980s, scientists discovered that CFCs were causing major damage to the ozone layer that protects the earth from ultra-violet radiation and the ozone holes over polar regions. This led to the signing of the Montreal Protocol in 1989 which aimed to phase-out CFCs and HCFC[5] but did not address the contributions that HFCs made to climate change. The adoption of HCFCs such as R-22, and R-123[2][6] was accelerated and so were used in most U.S. homes in air conditioners and in chillers[7] from the 1980s as they have a dramatically lower Ozone Depletion Potential (ODP) than CFCs, but their ODP was still not zero which led to their eventual phase-out.

Hydrofluorocarbons (HFCs) such as R-134a,[8] R-143a, R-407a,[9] R-407c,[10] R-404a[4] and R-410a[11] (a 50/50 blend of R-125/R-32) 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,[12] R-290,[13] R-600a,[13] R-454b,[14] R-1234yf,[15] R-514A,[16] R-744 (CO2),[17] R-1234ze[18] and R-1233zd,[19] which have both an ODP of zero and a lower GWP. Hydrocarbons and CO
2
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 an alternative ozone and climate-safe refrigerant in 1992. The company developed a hydrocarbon mix of isopentane and isobutane, but as a condition of the contract with Greenpeace could not patent the technology, which led to its widespread adoption by other firms.[20][21][22] Policy and political influence by corporate executives resisted change however[23][24] and DuPont together with other companies blocked the refrigerant in the U.S. with the U.S. EPA.[25][26]

Beginning on November 14, 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.[27] In 1995, Germany made CFC refrigerators illegal.[28]

In 1996 Eurammon, a European non-profit initiative for natural refrigerants, was established and comprises European companies, institutions, and industry experts.[29][30]

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[31] 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 between 2010 for virgin fluid and from 2015 for recycled fluid.[citation needed]

Addressing Greenhouse gases[edit]

With growing interest in natural refrigerants as alternatives to synthetic refrigerants such as CFCs, HCFCs and HFCs, in 2004, Greenpeace worked with multinational corporations like Coca-Cola and Unilever, and later Pepsico and others, to create a corporate coalition called Refrigerants Naturally!.[28][32] Four years later, Ben & Jerry's of Unilever and General Electric began to take steps to support production and use in the U.S.[33] It is estimated that almost 75 percent of the refrigeration and air conditioning sector has the potential to be converted to natural refrigerants.[34]

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 and some refrigerants are being used as recreational drugs, leading to an extremely dangerous phenomenon known as inhalant abuse.[35]

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 1410.[36] In the same year the EPA decided in favor of the ozone- and climate-safe refrigerant for U.S. manufacture.[20][37][38]

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.[39]

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.[40] and in the same year the UNEP published new voluntary guidelines,[41] however many countries have not yet ratified the Kigali Amendment.

As of 2020 HFCs (including R-404a, R-134a and R-410a) are being superseded: with residential air-conditioning systems using R-32 or R-600 (isobutane); car air-conditioning systems using R-1234yf; chillers for commercial refrigeration; air conditioning using R-1234ze; and, commercial refrigeration using CO
2
(R-744).

Desirable properties[edit]

The ideal refrigerant would be: non-corrosive, non-toxic, non-flammable, with no ozone depletion and global warming potential. It also 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. 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.[42]

Examples of refrigerants[edit]

Some common refrigerants are:

Code Chemical Status Commentary
R-12 Dichlorodifluoromethane Banned 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.[43]
R-22 Chlorodifluoromethane Being phased out A widely used hydrochlorofluorocarbon (HCFC) and powerful greenhouse gas with a GWP equal to 1810. Worldwide production of R-22 in 2008 was about 800 Gg per year, up from about 450 Gg per year in 1998. R-438a (MO-99) is a R-22 replacement.[44]
R-717 Ammonia Has zero ozone depletion and zero global warming potential.[citation needed] Commonly used before the popularisation of CFCs it is again being considered, but does suffer from the disadvantage of toxicity, and requiring 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.
R-32 Difluoromethane Has excellent heat transfer and pressure drop performance, both in condensation and vaporisation.[45] It has a 100-year global warming potential (GWP) of 675 times that of carbon dioxide, and an atmospheric lifetime of nearly 5 years.[46] is currently used in residential and commercial air-conditioners and heat pumps.
R-152a Difluoroethane Widely Used Commonly used as a compressed air duster.
R-290 Propane Low cost, widely available and efficient. They also have zero ozone depletion potential and very low global warming potential. Despite the flammability, they are increasingly used in domestic refrigerators. 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.[47]
R-407c Mixture of difluoromethane and pentafluoroethane and 1,1,1,2-tetrafluoroethane Widely Used a mixture of R-32, R-125, and R-134a
R-410a Mixture of difluoromethane and pentafluoroethane Widely Used R-454B is planned to be used new air conditioning equipment. R-32 is presently use in new conditioning equipment.[48]|
R-600a Isobutane See R-290.
R-744 CO2 Was used as a refrigerant prior to the discovery of CFCs (this was also the case for propane)[1] and now having a renaissance due to it being non-ozone depleting, non-toxic, non-flammable with a low Global warming potential of 1. It may become the working fluid of choice to replace current HFCs in cars, supermarkets, and heat pumps. Coca-Cola has fielded CO2-based beverage coolers and the U.S. Army is considering CO2 refrigeration.[49][50] Due to the need to operate at pressures of up to 130 bars (1,900 psi; 13,000 kPa), CO2 systems require highly resistant components, however these have already been developed for mass production in many sectors.
HFO-1234yf 2,3,3,3-Tetrafluoropropene Has a global warming potential (GWP) of less than 1,[51][52] compared to 1,430 for R-134a.[36] GM announced that it would start using "hydrofluoroolefin", HFO-1234yf, in all of its brands by 2013.[53]
R-134a 1,1,1,2-Tetrafluoroethane Widely Used R-513A {an HFO/HFC blend (56% R-1234yf/44%R-134a)} may replace R-134a as an interim alternative[54]
R-454B Difluoromethane and 2,3,3,3-Tetrafluoropropene R-454B is an HFOs blend of refrigerants Difluoromethane (R-32) and 2,3,3,3-Tetrafluoropropene (R-1234yf).[55][56][57][58]

Refrigerant reclamation and disposal[edit]

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.[59]

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.[60][61]

Refrigerant reclamation is the act of processing used refrigerant gas which 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.[62]

Classification of refrigerants[edit]

R407C pressure-enthalpy diagram, isotherms between the two saturation lines

Refrigerants may be divided into three classes according to their manner of absorption or extraction of heat from the substances to be refrigerated:[citation needed]

  • Class 1: This class includes refrigerants that cool by phase change (typically boiling), using the refrigerant's latent heat.
  • Class 2: These refrigerants cool by temperature change or 'sensible heat', the quantity of heat being the specific heat capacity x the temperature change. They are air, calcium chloride brine, sodium chloride brine, alcohol, and similar nonfreezing solutions. The purpose of Class 2 refrigerants is to receive a reduction of temperature from Class 1 refrigerants and convey this lower temperature to the area to be cooled.
  • Class 3: This group consists of solutions that contain absorbed vapors of liquefiable agents or refrigerating media. These solutions function by nature of their ability to carry liquefiable vapors, which produce a cooling effect by the absorption of their heat of solution. They can also be classified into many categories.

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. The meaning of the codes is as follows:[citation needed]

  • For saturated hydrocarbons, subtracting 90 from the concatenated numbers of carbon, hydrogen and fluorine atoms, respectively gives the assigned R#.[63]
  • If bromine is present, the number is followed by a capital B and then the number of bromine atoms.
  • Remaining bonds not accounted for are occupied by chlorine atoms.
  • A suffix of a lower-case letter a, b, or c indicates increasingly unsymmetrical isomers.

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 R-400 series is made up of zeotropic blends (those where the boiling point of constituent compounds differs enough to lead to changes in relative concentration because of fractional distillation) and the R-500 series is made up of so-called azeotropic blends. The rightmost digit is assigned arbitrarily by ASHRAE, an industry standards organization.
  • The R-700 series is made up of non-organic refrigerants, also designated by ASHRAE.

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.[citation needed]

See also[edit]

References[edit]

  1. ^ a b http://www.r744.com/files/pdf_597.pdf
  2. ^ a b c "Finally, a replacement for R123?". Cooling Post. October 17, 2013.
  3. ^ https://www.hagerty.com/media/maintenance-and-tech/air-conditioning-dos-and-donts-refrigerants-and-the-law/amp/ https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/download/3297/1244/
  4. ^ a b "What's the Latest with R-404A?". www.achrnews.com.
  5. ^ "Air Conditioners & Dehumidifiers". Sylvane. July 2011.
  6. ^ https://www.trane.com/content/dam/Trane/Commercial/global/products-systems/education-training/industry-articles/ASHRAE012017_Chemical%20Stability%20Assessments%20of%20R-1233zd(E)%20and%20R-514A.pdf
  7. ^ https://ec.europa.eu/clima/sites/clima/files/docs/0007/mcquay_hfc_scroll_chillers_paper_en.pdf
  8. ^ https://www.achrnews.com/articles/135112-whats-happening-with-r-134a https://www.techtips.ie/Hella-Ireland/aircon-conversion-r12r134a.pdf
  9. ^ "R-407A Gains SNAP OK". www.achrnews.com.
  10. ^ "June 26, 2009: Emerson Approves R-407A, R-407C for Copeland Discus Compressors". www.achrnews.com.
  11. ^ "Taking New Refrigerants to the Peak". www.achrnews.com.
  12. ^ "Daikin reveals details of R32 VRV air conditioner". Cooling Post. February 6, 2020.
  13. ^ a b "Refrigerant blends to challenge hydrocarbon efficiencies". Cooling Post. December 22, 2019.
  14. ^ "An HVAC Technician's Guide to R-454B". www.achrnews.com.
  15. ^ https://autoexpert.com.au/posts/the-truth-about-new-automotive-ac-refrigerant-r1234yf https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2524&context=iracc
  16. ^ "Trane adopts new low GWP refrigerant R514A". Cooling Post. June 15, 2016.
  17. ^ "R404A – the alternatives". Cooling Post. February 26, 2014.
  18. ^ "Carrier expands R1234ze chiller range". Cooling Post. May 20, 2020.
  19. ^ "Carrier confirms an HFO refrigerant future". Cooling Post. June 5, 2019.
  20. ^ a b "Happy birthday, Greenfreeze!". Greenpeace. Retrieved 8 June 2015.
  21. ^ "Ozone Secretariat". United Nations Environment Programme. Archived from the original on 12 April 2015.
  22. ^ Gunkel, Christoph (13 September 2013). "Öko-Coup aus Ostdeutschland". Der Spiegel (in German). Retrieved 4 September 2015.
  23. ^ Mate, John "Making a Difference: A Case Study of the Greenpeace Ozone Campaign" RECIEL 10:2 2001.
  24. ^ Benedick, Richard Elliot Ozone Diplomacy Cambridge, MA: Harvard University 1991.
  25. ^ "Discurso de Frank Guggenheim no lançamento do Greenfreeze | Brasil". Greenpeace.org. Retrieved 10 June 2015.
  26. ^ "Der Greenfreeze - endlich in den USA angekommen". Greenpeace.de (in German). 28 December 2011. Retrieved 10 June 2015.
  27. ^ "Complying With The Section 608 Refrigerant Recycling Rule | Ozone Layer Protection - Regulatory Programs". Epa.gov. 21 April 2015. Retrieved 10 June 2015.
  28. ^ a b "Greenfreeze: a Revolution in Domestic Refrigeration". ecomall.com. Retrieved 8 June 2015.
  29. ^ "Company background".
  30. ^ IPCC/TEAP Special Report: Safeguarding the ozone layer and the global climate System: issues related to Hydrofluorocarbons and Perfluorocarbons, 2005. [1] Crowley, Thomas J.; “Causes of Climate Change Over the Past 1000 Years” Science 14 July 2000: Vol. 289. no. 5477, pp. 270–277.
  31. ^ "2010 to 2015 government policy: environmental quality". GOV.UK. 8 May 2015. Retrieved 10 June 2015.
  32. ^ "PepsiCo Brings First Climate-Friendly Vending Machines to the U.S." phx.corporate-ir.net. Retrieved 8 June 2015.
  33. ^ "Climate-Friendly Greenfreezers Come to the United States". WNBC. Retrieved 8 June 2015.
  34. ^ Data, Reports and (2020-08-07). "Natural Refrigerants Market To Reach USD 2.88 Billion By 2027 | Reports and Data". GlobeNewswire News Room. Retrieved 2020-12-17.
  35. ^ Harris, Catharine. "Anti-inhalant Abuse Campaign Targets Building Codes: 'Huffing’ of Air Conditioning Refrigerant a Dangerous Risk." The Nation's Health. American Public Health Association, 2010. Web. 05 Dec. 2010. http://thenationshealth.aphapublications.org/content/39/4/20.extract.
  36. ^ a b P. Forster; V. Ramaswamy; P. Artaxo; T. Berntsen; R. Betts; D.W. Fahey; J. Haywood; J. Lean; D.C. Lowe; G. Myhre; J. Nganga; R. Prinn; G. Raga; M. Schulz; R. Van Dorland (2007). "Chapter 2: Changes in atmospheric constituents and in radiative forcing". In Solomon, S.; Miller, H.L.; Tignor, M.; Averyt, K.B.; Marquis, M.; Chen, Z.; Manning, M.; Qin, D. (eds.). Climate Change 2007: the physical science basis. Contribution of Working Group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. Retrieved 9 October 2016.
  37. ^ "GreenFreeze". Greenpeace.
  38. ^ "Significant New Alternatives Program: Substitutes in Household Refrigerators and Freezers". Epa.gov. 13 November 2014. Retrieved 4 June 2018.
  39. ^ Berwald, Juli (2019-04-29). "One overlooked way to fight climate change? Dispose of old CFCs". National Geographic - Environment. Retrieved 2019-04-30.
  40. ^ Butler J. and Montzka S. (2020). "The NOAA Annual Greenhouse Gas Index (AGGI)". NOAA Global Monitoring Laboratory/Earth System Research Laboratories.
  41. ^ Environment, U. N. (2019-10-31). "New guidelines for air conditioners and refrigerators set to tackle climate change". UN Environment. Retrieved 2020-03-30.
  42. ^ Rosenthal, Elisabeth; Lehren, Andrew (June 20, 2011). "Relief in Every Window, but Global Worry Too". The New York Times. Retrieved June 21, 2012.
  43. ^ "1:Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol". Scientific assessment of ozone depletion: 2018 (PDF) (Global Ozone Research and Monitoring Project–Report No. 58 ed.). Geneva, Switzerland: World Meteorological Organization. 2018. p. 1.10. ISBN 978-1-7329317-1-8. Retrieved 22 November 2020.
  44. ^ [1] Chemours M099 as R22 Replacement
  45. ^ Longo, Giovanni A.; Mancin, Simone; Righetti, Giulia; Zilio, Claudio (2015). "HFC32 vaporisation inside a Brazed Plate Heat Exchanger (BPHE): Experimental measurements and IR thermography analysis". International Journal of Refrigeration. 57: 77–86. doi:10.1016/j.ijrefrig.2015.04.017.
  46. ^ May 2010 TEAP XXI/9 Task Force Report
  47. ^ "Protection of Stratospheric Ozone: Hydrocarbon Refrigerants" (PDF). Environment Protection Agency. Retrieved 5 August 2018.
  48. ^ [2] A Conversation on Refrigerants | ASHRAE Journal, March 2021 | page 36, column 2, paragraph 5
  49. ^ "The Coca-Cola Company Announces Adoption of HFC-Free Insulation in Refrigeration Units to Combat Global Warming". The Coca-Cola Company. 5 June 2006. Retrieved 11 October 2007.
  50. ^ "Modine reinforces its CO2 research efforts". R744.com. 28 June 2007. Archived from the original on 10 February 2008.
  51. ^ Scientific Assessment of Ozone Depletion: 2014 Full Report. World Meteorological Organization Global Ozone Research and Monitoring Project—Report No. 55. 2014. p. 551.
  52. ^ "IPCC confirms HFO GWPs are less than 1". Cooling Post. 3 Feb 2014. Retrieved 26 July 2018.
  53. ^ GM First to Market Greenhouse Gas-Friendly Air Conditioning Refrigerant in U.S.
  54. ^ [3] A Conversation on Refrigerants | ASHRAE Journal, March 2021 | page 30, column 1, paragraph 2
  55. ^ [4] R-454B XL41 Refrigerant Fact & Info Sheet
  56. ^ [5] R-454B Emerges As A Replacement For R-410A | ACHR NEWS (Air Conditioning, Heating, Refrigeration News)
  57. ^ [6] CCARRIER introduces [R-454B] PURON ADVANCE™ as the next generation refrigerant for ducted residential, light commercial products in North America | Indianapolis - Dec. 19, 2018
  58. ^ [7] Johnson Controls Selects R-454B As Future Refrigerant For New HVAC Equipment | May 27, 2021
  59. ^ "Emissions of Greenhouse Gases in the United States 1998 - Executive Summary". August 18, 2000. Archived from the original on 2000-08-18.
  60. ^ "Frequently Asked Questions on Section 608". Environment Protection Agency. Retrieved 20 December 2013.
  61. ^ "US hydrocarbons". Retrieved 5 August 2018.
  62. ^ "42 U.S. Code § 7671g - National recycling and emission reduction program". LII / Legal Information Institute.
  63. ^ "Numbering Scheme for Ozone-Depleting Substances and their Substitutes". Retrieved 25 December 2015.

External links[edit]