In a system using a capillary tube, how is the superheat affected when very little heat is absorbed?

In a system utilizing a capillary tube, when very little heat is absorbed, the condition of the refrigerant becomes critical to understanding superheat. Superheat refers to the amount of heat added to the refrigerant vapor after it has completely evaporated and is in a gaseous state.

When minimal heat is absorbed, the refrigerant does not fully evaporate; thus, the temperature of the vapor can remain close to or even at the saturation point corresponding to the evaporating pressure. As a result, the refrigerant may not attain a superheated state because the effective heating is insufficient to raise its temperature above the saturation temperature. This situation leads to the conclusion that there will be little or no superheat present in the system.

This phenomenon is particularly pertinent in capillary tube systems, where the flow of refrigerant is affected by thermal conditions and any inefficacy in heat absorption can severely limit the vaporization process. Inadequate heat absorption means that the refrigerant does not properly transition into a gas before it enters the compressor, which aligns with the idea that superheat is practically nonexistent under these conditions.