ESCO Air Conditioning Practice Exam

An increase in head pressure results in more refrigerant flowing through a capillary tube. This is due to the relationship between pressure and flow rate in a refrigerant system, where higher pressure can push refrigerant through the distanced passages of the capillary tube more effectively.

Capillary tubes are used in refrigeration and air conditioning systems as expansion devices. They function by creating a pressure drop, allowing the refrigerant to expand and absorb heat as it moves from the high-pressure side of the system to the low-pressure side. When head pressure increases, it raises the pressure differential across the capillary tube, thereby enabling a greater amount of refrigerant to flow through it.

This flow is dependent on both the pressure difference and the resistance imposed by the capillary tube, which has a fixed diameter and is sensitive to changes in upstream pressure. Therefore, as the head pressure rises, the amount of refrigerant that can be allowed to flow increases correspondingly to the increased pressure, making "more" the accurate response to the impact of increased head pressure on refrigerant flow.