Although vapor-compression refrigeration is a simple concept, there are still a lot of details in the implementation of such ...
The capillary tube has been used as a refrigerant metering device for many decades. Many HVACR manufacturers are still successfully employing capillary tube metering devices in their latest equipment.
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.