EXAIR has published numerous articles detailing the functionality and applications of Vortex Tubes. This innovative technology, which produces cold air without the use of Freon or mechanical components, is rooted in physical principles and has been known by various names, such as the Ranque Tube, Ranque-Hilsch Tube, and Maxwell’s Demon. Today, it is commonly referred to as the Vortex Tube, capable of generating air temperatures as low as -50 °F (-46 °C) through the high-speed rotation of compressed air. In this article, I will discuss how to adjust the Vortex Tube to achieve varying temperatures and cooling effects, focusing on the concept of Cold Fraction.

The term “Cold Fraction” refers to the proportion of supply air allocated to the cold end of a system. A higher Cold Fraction indicates an increased flow and temperature of the cold air, while a lower Cold Fraction results in diminished cold air flow and temperature.
The performance chart below illustrates how the settings for “Pressure Supply” and “Cold Fraction %” influence the operation of Vortex Tubes. For instance, with an operating pressure of 100 PSIG and a cold fraction set at 20%, the cold side experiences a temperature drop of 123°F, while the hot side sees a rise of 26°F. Conversely, maintaining the same pressure of 100 PSIG but adjusting the cold fraction to 80% results in a 54°F decrease on the cold side and a significant 191°F increase on the hot side.
In a convection or conduction air cooling application, two key factors must be considered: the air flow rate and the temperature difference between the cooling air and the heated component. It is advisable to begin with the maximum cold fraction; however, you may discover that a slightly reduced flow rate, along with the corresponding lower temperature, could better meet your requirements. The positive aspect of this adjustment is that it does not affect compressed air consumption, allowing you to enhance performance without incurring additional operational costs.
If you have any questions about Vortex Tubes, or anything regarding EXAIR and our products, please do not hesitate to reach out. We would love to hear from you!
Jason Kirby
Application Engineer
Email: jasonkirby@exair.com
Twitter: @EXAIR_jk












