Superheat the refrigerant in the suction line of the compression chiller

1. As you know, the evaporation of the refrigerant liquid takes place in the evaporator coils.

Also, as soon as the refrigerant liquid starts to evaporate, it moves inside the evaporator coils of the chiller. As the amount of refrigerant evaporation increases, the amount of liquid refrigerant decreases until at the end of the evaporator coil, the refrigerant is completely evaporated, but it is still cooler than the objects around the coil. Therefore, whenever sensible heat enters from the surroundings of the evaporator, the refrigerant vapor absorbs the sensible heat, but because the refrigerant has already completely evaporated, the temperature of the refrigerant rises above its saturation temperature by absorbing more heat, in this case, It is called superheat vapor (super hot) refrigerant.

In fact, the superheat temperature is the temperature added to the suction gas of the compression refrigeration cycle, which is higher than the saturation temperature of the refrigerant gas.

2. The purpose of superheating the refrigerant is to prevent the possibility of the refrigerant liquid entering the chiller compressor because due to the incompressibility of liquids, liquid entering the compressor causes the chiller compressor valves to break.
Of course, on the other hand, when the evaporator faces a shortage of refrigerant liquid, there is not enough refrigerant in the evaporator, for this reason, the existing refrigerant evaporates much faster than its time, and this causes the inability of the refrigerant to absorb the entire thermal load of the building. be made

3. In chillers and mini chillers and DX direct expansion systems where the refrigerant liquid is directly injected into the cold coils of the chiller, the lack of refrigerant can be detected by accurately measuring the amount of superheat of the refrigerant gas after leaving the evaporator, especially at the time of full load. measured

4. If thermostatic valves are used in refrigeration systems, according to the type of design, the amount of superheat is almost constant.

5. In normal working conditions, this temperature difference for the refrigerant is 10 to 20 degrees Fahrenheit or 5 to 10 degrees Celsius, and if this value of superheat temperature remains constant in all load changes, it is possible to understand the appropriateness of charging the refrigerant gas.