Why do Some Refrigerants Have to be Charged in Liquid?

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Is R22 refrigerant gaseous or liquid? Is the refrigerant of R410A gaseous or liquid? Why do some refrigerants have to be liquid? Let’s first look at the principle of charging refrigerant.

Charging principle of Refrigerant

1. Liquid charging

Because the generally used steel cylinder contains liquid refrigerant, after the cylinder is inverted, the liquid refrigerant enters the refrigeration system through the liquid addition pipe. However, the fluorine discharge port of some cylinders will extend to the bottom of the cylinder. At this time, although the cylinder is upright, the liquid refrigerant is added.

2. Gaseous charging

Charging gaseous refrigerant actually means that the refrigerant cylinder is standing upright. Since the upper space of the cylinder is already gaseous refrigerant, the gaseous refrigerant is added to the refrigeration system at this time.

Why do you need to charge refrigerant in gas and liquid?

1. Three concepts

Refrigerants are divided into single refrigerants, non-azeotropic refrigerants, and azeotropic refrigerants.

Single working medium refrigerant: The refrigerant has only one working medium, such as R22 and R290.

Non-azeotropic refrigerant: a refrigerant that is a mixture of two or more different refrigerants in a certain proportion. In the saturated state, the composition of the gas-liquid two phases is different, such as R404A, R410A.

Azeotropic refrigerant: An azeotropic mixture formed by mixing two or more different refrigerants in a certain proportion. This type of refrigerant can maintain a certain evaporation temperature under a certain pressure, and its gas-liquid two-phase always maintains the same composition ratio, such as R500, R508A.

2. Liquid or gas?

The composition of the single working substance refrigerant will not change whether it is gaseous or liquid, so the gaseous state can be charged when charging the refrigerant.

Although the composition of the azeotropic refrigerant is different, because the boiling point is the same, the composition of the gas and liquid is also the same, it can be charged in the gaseous state.

Due to the different boiling points of non-azeotropic refrigerants, liquid refrigerants and gaseous refrigerants are actually different in composition. At this time, if the gaseous state is added, the composition of the refrigerant added will be different, so only the liquid state can be added.

How to distinguish simple, azeotropic and non-azeotropic refrigerant?

1. The standard stipulates that the first number after R is “5” for azeotropic refrigerants, and the two numbers after it are numbered in practical order, such as R500, R501, R502… R507

2. Non-azeotropic refrigerants have not been numbered in the refrigerant numbering standard, but the numbering sequence of No. 400 after R is reserved for supplementary numbers, such as: R400, R401, R402, … R411


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