You might wonder how the capillary tube expansion valve in HVAC&R works as it doesn’t have any moving parts and is very simple and small in size.
It is just made up of tiny hollow copper tubes. It is usually wound together like a spring coil, but it cannot be used as a spring. (Check the “How does expansion valve work?”)
Because this can effectively ensure the flow of refrigerant. It also saves the space installed on the refrigeration equipment.
Surprisingly, it is the simplest and most cost-effective expansion valve out there, consisting of a small-diameter capillary tube.
This wound-up copper tube is designed to receive hot, high-pressure liquid refrigerant from the condenser.
But how does it maintain pressure on both sides of the capillary expansion valve (evaporator side and condenser side)?
The answer is the friction with the tube’s walls.
Friction reduces the speed of all objects including gases and liquids.
The same is true for refrigerants. (If you are confused, please check the “What is refrigeration system?”)
In a capillary tube, the refrigerant flow is restricted by the tube’s size.
The diameter and length of the capillary tube therefore directly determines the energy efficiency of the expansion valve, you can check how to choose the right capillary tube here.
If you compare a capillary tube expansion valve with a thermostatic expansion valve and an electronic expansion valve, it is the most durable and cost-effective option because of its small size, simple design, and lack of moving parts.
It became a preferred choice for units produced in large quantities, such as small refrigeration units, indoor condensing units, commercial refrigeration condensing units, remote condensing units, drop-in refrigeration units, self-contained refrigeration units, horizontal condensing units, etc.
If you have a sourcing requirement for capillary tubes, please contact us now as we can supply you with standard-length capillary tubes and customized capillary tubes.