What happens to refrigerant flow when pressure across the capillary tube increases?

When pressure across the capillary tube increases, the behavior of the refrigerant flow is influenced by the characteristics of the capillary tube itself. A capillary tube is typically used in refrigeration systems as a metering device that helps regulate the flow of refrigerant into the evaporator.

As the pressure increases, the refrigerant's ability to flow through the capillary tube can change significantly. Specifically, an increase in pressure generally leads to an increase in the density of the refrigerant, allowing it to flow more readily through the tube. The pressure difference created by higher upstream pressure effectively pushes the refrigerant with greater force, facilitating a higher flow rate through the capillary tube.

Additionally, in a system where the capillary tube is sized correctly for the application, higher pressure should correlate with an increase in flow as long as the temperature conditions and the overall system are operating within designed parameters. This phenomenon is a key aspect of how capillary tubes function, allowing them to efficiently regulate refrigerant flow based on pressure conditions in the system.

The understanding of the relationship between pressure and refrigerant flow through capillary tubes is essential for HVAC technicians, as it can help diagnose system performance and efficiency issues.