In refrigerated systems such as refrigerators, household refrigerators, displays, drinking fountains and freezers, as well as others; the most used expansion device is a capillary tube. In addition to a lower cost compared with an expansion valve, this in turn, when properly dimensioned, corresponds to the desired evaporating temperature expectations.
It is usually applied in matches equalized systems.
Its function: to provide a pressure drop and temperature of the subcooled refrigerant and respectively regulate its flow rate (mass flow) in the evaporator.
This fact is caused by the friction along the capillary tube, caused by the passage of refrigerant in liquid form.
The pressure drop inside the evaporator depends greatly on the diameter and length of the capillary applied. In the case of evaporating pressure reduction it is necessary that an increase in the length of the capillary or decreased its diameter.
