The capillary tube — the simplest of refrigerant controls — is the most popular method for metering refrigerant flow from the condenser to the evaporator in compression-type refrigeration systems.

The capillary tube is a very popular metering device used on many fractional horsepower refrigeration systems. It is basically a length of very small diameter copper tubing soldered or brazed between ...

Going down: a droplet of honey in a superhydrophobic coated tube. (Courtesy: Aalto University) Honey and other highly viscous fluids can flow faster than water in specially coated capillary tubes.