Editing Refrigerant (section)

== Classification of refrigerants ==
[[File:R407C eng.PNG|thumbnail|R407C [[pressure]]-[[enthalpy]] diagram, isotherms between the two saturation lines]]
{{main|List 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:{{citation needed|date=December 2013}}
* 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 the 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.

===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:<ref>{{cite web |author1=ASHRAE |author2=UNEP |title=Designation and Safety Classification of Refrigerants |url=https://www.ashrae.org/file%20library/technical%20resources/standards%20and%20guidelines/standards%20addenda/34_2004_add-g.pdf |website=ASHRAE |access-date=1 July 2023 |date=Nov 2022}}</ref>

<big>'''R-X<sub>1</sub>X<sub>2</sub>X<sub>3</sub>X<sub>4</sub>'''</big>

*'''X<sub>1</sub>''' = Number of unsaturated carbon-carbon bonds (omit if zero)
*'''X<sub>2</sub>''' = Number of carbon atoms minus 1 (omit if zero)
*'''X<sub>3</sub>''' = Number of hydrogen atoms plus 1
*'''X<sub>4</sub>''' = Number of fluorine atoms

====Series====
* '''R-xx'''	[[Methane]] Series
* '''R-1xx'''	[[Ethane]] Series
* '''R-2xx'''	[[Propane]] Series
* '''R-4xx'''	[[Zeotropic mixture|Zeotropic blend]]
* '''R-5xx'''	[[Azeotrope|Azeotropic blend]]
* '''R-6xx'''	Saturated hydrocarbons (except for propane which is R-290)
* '''R-7xx'''	Inorganic Compounds with a [[molar mass]] < 100
* '''R-7xxx'''	Inorganic Compounds with a molar mass ≥ 100

====Ethane Derived Chains====
* '''Number Only'''	Most symmetrical [[isomer]]
* '''Lower Case Suffix (a, b, c, etc.)'''	indicates increasingly unsymmetrical isomers

====Propane Derived Chains====
* '''Number Only'''	If only one isomer exists; otherwise:
* '''First lower case suffix (a-f):'''
** '''a Suffix'''	Cl<sub>2</sub> central carbon substitution
** '''b Suffix'''	Cl, F central carbon substitution
** '''c Suffix'''	F<sub>2</sub> central carbon substitution
**'''d Suffix'''	Cl, H central carbon substitution
**'''e Suffix'''	F, H central carbon substitution
** '''f Suffix'''	H<sub>2</sub> central carbon substitution
* '''2nd Lower Case Suffix (a, b, c, etc.)'''	Indicates increasingly unsymmetrical isomers

====Propene derivatives====
* '''First lower case suffix (x, y, z)''':
**'''x Suffix'''	Cl substitution on central atom
** '''y Suffix'''	F substitution on central atom
**'''z Suffix'''	H substitution on central atom
* '''Second lower case suffix (a-f)''':
**'''a Suffix'''	=CCl<sub>2</sub> [[Methylene group|methylene]] substitution
** '''b Suffix'''	=CClF methylene substitution
**'''c Suffix'''	=CF<sub>2</sub> methylene substitution
** '''d Suffix'''	=CHCl methylene substitution
**'''e Suffix'''	=CHF methylene substitution
**'''f Suffix'''	=CH<sub>2</sub> methylene substitution

====Blends====
* '''Upper Case Suffix (A, B, C, etc.)'''	Same blend with different compositions of refrigerants

====Miscellaneous====
* '''R-Cxxx''' [[Cyclic compound]]
* '''R-Exxx''' [[Ether|Ether group]] is present
* '''R-CExxx'''	Cyclic compound with an ether group
* '''R-4xx/5xx + Upper Case Suffix (A, B, C, etc.)'''	Same blend with different composition of refrigerants
* '''R-6xx + Lower Case Letter'''	Indicates increasingly unsymmetrical isomers
* '''7xx/7xxx + Upper Case Letter'''	Same molar mass, different compound
* '''R-xxxxB#'''	[[Bromine]] is present with the number after B indicating how many bromine atoms
* '''R-xxxxI#'''	[[Iodine]] is present with the number after I indicating how many iodine atoms
* '''R-xxx(E)'''	Trans Molecule
* '''R-xxx(Z)'''	Cis Molecule

For example, [[1,1,1,2-Tetrafluoroethane|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 [[hydrofluorocarbon]]s, CFC- for [[chlorofluorocarbon]]s, and HCFC- for [[hydrochlorofluorocarbon]]s has arisen, because of the regulatory differences among these groups.{{citation needed|date=August 2015|ASHRAE std 34-1997, Section 5.2.2 = }}