How is superheat decreased in a system with a capillary tube?

In a refrigeration system equipped with a capillary tube, superheat is the measure of how much the vapor refrigerant's temperature exceeds its saturation temperature at the corresponding pressure. To decrease superheat, one effective method is to add more refrigerant to the system.

When more refrigerant is introduced into the system, it increases the liquid refrigerant flow through the capillary tube. This enhanced flow helps to ensure that more refrigerant is available to be vaporized in the evaporator, effectively reducing the amount of superheat present in the vapor refrigerant exiting the evaporator. By having an adequate supply of refrigerant, the system can operate more efficiently and reduce the excess temperature of the vapor refrigerant, thus decreasing the superheat.

Other methods such as lowering the ambient temperature or increasing the pressure may influence the overall system performance but do not directly address the superheat issue in the same way. Decreasing the refrigerant flow rate generally leads to increased superheat, as less liquid is available for vaporization, causing more of the vapor to be above its saturation temperature.