Refrigerants are also called refrigerants agent in refrigeration systems. At present, there are more than 80 substances. They can be used as refrigerants. The most common refrigerants are Freon (including: R22, R134a, R407c, R410a, R32, etc.), ammonia (NH3), water (H2O), and carbon dioxide (CO2) A few hydrocarbons (such as: R290, R600a).
- Classification of refrigerants according to the evaporation temperaturets of the refrigerant under standard atmospheric pressure (100kPa) conditions, it can be divided into: high temperature refrigerant, medium temperature refrigerant, and low temperature refrigerant.
High-temperature refrigerants (or low-pressure refrigerants), such as R113, R114, and R21, are often used in air-conditioning systems of centrifugal refrigerators.
Medium temperature refrigerants (or medium pressure refrigerants), such as: R22, R717, R142, R502, are often used in common single-stage and double-stage compression piston refrigeration compressors.
High-temperature refrigerants (or high-pressure refrigerants), such as: R503, alkanes, and olefins, are often used in the low-temperature stage of cascade refrigeration devices. In addition, according to different chemical compositions, refrigerants can be divided into the following categories:
1) Inorganic compound: In the code of inorganic compound refrigerant, the first number after R is 7, and the number following it is the integer part of molecular weight.
2) Halides of saturated hydrocarbons (Freon): The code for Freon is the letter R, followed by the number (m-1) (n + 1) (x) B (z). When m = 1, (m-1) can be omitted; if z = 0, B (z) can be omitted.
3) Hydrocarbons: Saturated hydrocarbons are also written according to Freon’s numbering rules, except R600 except butane. In addition, the isomers are added with a letter “a” after the code. For example, isobutyrate is R600a.
Unsaturated hydrocarbons and their halogen element derivatives. Write a “1” after R, and then write the number according to the Freon numbering scheme.
4) Azeotropic refrigerant: The first number after R in the azeotropic refrigerant is specified in the numbering standard, and the next two digits are numbered in practical order, such as R500, R501, etc.
5) Non-azeotropic refrigerant:
For non-azeotropic refrigerants, the first digit after R is 4 and the next two digits are numbered in practical order, such as R400, R401, R407A, R407B, R407C, etc.
Note: To distinguish the extent of Freon’s damage to the atmospheric ozone layer, R is often replaced by CFC, HCFC, HFC, HC, respectively.
CFC-chlorofluorocarbon, containing chlorine, no hydrogen, pollution, serious damage to the ozone layer banned HCFC-hydrochlorofluorocarbon, containing chlorine, hydrogen, low-pollution substances are transition materials HFC-hydrofluorination Carbon, no chlorine, no pollution can be used as an alternative HC-hydrocarbon, no chlorine, no fluorine, no pollution can be used as an alternative.