Refrigerant

The refrigerant is a working substance for performing a refrigeration cycle in a refrigerating device. The working principle is that the refrigerant absorbs heat of the cooled substance in the evaporator and evaporates, and the absorbed heat is transferred to the surrounding air or water in the condenser. It is cooled to a liquid, reciprocatingly cycled, and the effect of refrigeration is achieved by means of a change in state. Commonly used refrigerants are ammonia (R717) and Freon (fluorochloroalkane) (R22, R134a, R410A, etc.).

Refrigerant classification

Low pressure high temperature refrigerant

The condensing pressure Pk ≤ 2 to 3 kg / cm (absolute), T0 > 0 ° C. For example, R11 (CFCl3), T0 = 23.7 °C. This type of refrigerant is suitable for use in centrifugal refrigeration compressors for air conditioning systems. Usually at 30 ° C, Pk ≤ 3.06 kg / cm.

Medium pressure medium temperature refrigerant

The condensing pressure Pk < 20 kg / cm (absolute), 0 ° C > T0 > -60 ° C. Such as R717.R12.R22, etc., such refrigerants are generally used in ordinary single-stage compression and two-stage compression piston refrigeration compressors.

High pressure low temperature refrigerant

Condensing pressure Pk ≥ 20 kg / cm (absolute), T0 ≤ -70 ° C. Such as R13 (CF3Cl), R14 (CF4), carbon dioxide, ethane, ethylene, etc., such refrigerants are suitable for use in low temperature parts of cascade refrigeration units or cryogenic units below -70 °C.

Coolant

The brine is an intermediate substance, such as the commonly used air conditioning chilled water, which is cooled and cooled in the evaporator and then transported over long distances to cool the objects that need to be cooled. At present, the commonly used brine has water, which can only be used above 0 °C when the requirement is below 0 °C. Generally, a brine such as sodium chloride or an aqueous solution of calcium chloride or an aqueous solution of an organic compound such as ethylene glycol or propylene glycol is used.