About Vortex Tubes

Vortex tube
Cooling or Heating with the Vortex Tube

If I were to tell you that I can take a supply of ordinary compressed air and drop it’s temperature by 50°F without any type of refrigerant or electrical connection, you might be scratching your head a bit. That is of course unless you’ve been introduced to the wild world of Vortex Tubes. My favorite product among the EXAIR Product Line, the Vortex Tube does just that. With an ordinary supply of compressed air as the sole power source, and no moving parts, the Vortex Tube converts that airstream into a hot and cold flow that exit from opposite ends of the tube. No magic, witchcraft, or wizardry involved here. Just physics!

EXAIR’s Vortex Tubes are a low-cost, reliable, and maintenance-free solution to a variety of industrial spot cooling problems. With just an ordinary supply of compressed air, the Vortex Tube produces two streams of air: one hot and one cold. The Vortex Tube is capable of achieving a temperature drop/rise from your compressed air supply ranging from -50°F to +260°F (-46°C to +127°C). Flow rates range from 1-150 SCFM (28-4,248 SLPM) and cooling capacities of up to 10,200 Btu/hr. With all Vortex Tubes constructed of stainless steel, they’re resistant to corrosion and oxidation ensuring you years of reliable, maintenance-free operation.


Two primary different styles of Vortex Tubes are offered: maximum refrigeration and maximum cold temperature. Tubes for maximum refrigeration have an “R” type generator installed. These tubes are optimal for most industrial applications. Model numbers containing 32XX all have an “R” generator installed. For “cryogenic” type applications such as cooling lab samples or circuit testing, the maximum cold temperature tubes are recommended. These tubes have a “C” type generator installed. Model numbers beginning with 34XX all are designed for maximum cold temperatures. The difference between the two is in the volume of air at the cold end. While the 34XX tubes deliver a colder temperature, there is much less volume of cold air.

All Vortex Tubes are adjustable. At the hot air exhaust side of the tube is an adjustable valve that controls the amount of air permitted to escape from the tube. The more air that exhausts from the hot end, the colder the temperature drop at the cold end. But, as more air escapes there’s less overall volume. Finding that balance between cold temperature and cold airflow volume is key to a successful application.

As we all know, if there’s a knob to turn, button to press, or adjustment that can be made an operator is inevitably going to tinker with it. Day shift will blame the night shift, night shift blames the day shift, and it can present a problem when the Vortex Tube has been specifically tested and set to achieve the desired cold fraction. If you know the cold fraction you need, but would prefer to prevent it from being able to be adjusted, EXAIR can install a precisely drilled hot plug to set the cold fraction percentage to your specifications and eliminate any potential for it to be changed.

Vortex family

If you’d still prefer to keep the adjustability, but don’t have the capabilities to measure and set it yourself, we can also set any Vortex Tube to the desired cold fraction with the adjustable valve and send it to you ready to be installed. We’ll provide you with a special model number so you can rest assured that any time you need another it’ll come set to your specification.

If you have an application in your facility that you believe is a nice fit for a Vortex Tube, give us a call. Our team of Application Engineers is standing by ready to help you determine the best solution for your application.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Georges J Ranque: Father of the Vortex Tube

Georges J. Ranque is known as the inventor and father of the Ranque-Hilsch Vortex tube. The vortex tube is device that takes a compressed gas and generates hot and cold streams from a source of compressed gas. George accidentally discovered the phenomenon on accident while studying physics at Ecole Polytechnique in Paris France. Ranque was looking was performing an experiment on a vortex-based pump to vacuum up iron fittings; during the experiment he noticed that warm air was being expelled out of one side and cold air out of the other when he inserted a cone into one end of the vortex. In 1931 Ranque filed for a patent for the vortex tube and two years later presented a paper on it.

Georges vortex tube was all but lost and forgot about until 1945 when the German physicist Rudolph Hilsch published a paper on the device. This paper became widely read and exposed the vortex tube to the industrial manufacturing environment. This paper revived what was thought to be lost and led the vortex tube into what we see today.

How an EXAIR Vortex Tube operates

During World War 2 Georges Ranque started to develop different steels that would be used in military aviation efforts. He later went on to work at Aubert et Duval Steelworks as the Director of Metallurgical Laboratory. While at Duval he would continue to developing alloys for the aviation industry.

Interestingly, in 1972 he went on to publish a book on the search for the Philosophers Stone, a mythological chemical substance that Alchemist’s thought could be used to turn base metals into Gold. The following year in 1973 he passed away in his home just outside of Paris.

Here at EXAIR we have expanded the uses of Ranque’s original vortex tubes for various different cooling uses. The vortex tube can be found in our Cold Guns, Spot Coolers, and Cabinet Coolers. In many cases EXAIR’s spot coolers and cold guns have been used to replace coolant in simple milling and grinding applications. Also, EXAIR’s Cabinet Coolers have been keeping control cabinets from overheating for many decades. 

If you have any questions or want more information on how we use our vortex tubes to improve processes all over industry. Give us a call, we have a team of application engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Discovery of The Vortex Tube

There are many theories regarding the dynamics of a vortex tube and how it works. Many students have studied them in hopes of advancing the physics or as part of their undergrad studies. The man that started it all was not intentionally researching it, however.

The Vortex Tube was invented by accident in 1928, by George Ranque, a French physics student. He was performing experiments on a vortex-type pump that he had developed and noticed that warm air exhausted from one end and cold air from the other. Ranque quickly changed his focus from the pump to start a company taking advantage of the commercial possibilities for this odd little device that produced both hot and cold air, using only compressed air, with no moving parts. The company was not successful, and the vortex tube was forgotten until 1945 when Rudolph Hilsch, a German physicist, published a widely read paper on the device.

A vortex tube uses compressed air as a power source, has no moving parts, and produces hot air from one end and cold air from the other. The volume and temperature of the two air streams is adjustable with a valve built into the hot air exhaust.  Temperatures as low as -50°F (-46°C) and as high as 260°F (127°C) are possible.

Compressed air is supplied to a vortex tube and passes through nozzles that are tangent to an internal counterbore. As the air passes through it is set into a spiraling vortex motion at up to 1,000,000 rpm. The spinning stream of air flows down the hot tube in the form of a spinning shell, like a tornado (in red). The control valve at the end allows some of the warmed air to escape and what does not escape reverses direction and heads back down the tube as a second vortex (in blue) inside of the low-pressure area of the larger warm air vortex. The inner vortex loses heat and exits through the other end of as cold air.

It is thought that both the hot and cold air streams rotate in the same direction at the same angular velocity, even though they are traveling in opposite directions. A particle of air in the inner stream completes one rotation in the same time of an air particle in the outer stream. The principle of conservation of angular momentum would say that the rotational speed of the inner vortex should increase because the angular momentum of a rotating particle (L) is equal to the radius of rotation (r) times it’s mass (m) times its velocity (v).  L = r•m•v.  When an air particle moves from the outer stream to the inner stream, both its radius (r) and velocity (v) decrease, resulting in a lower angular momentum. To maintain an energy balance for the system, the energy that is lost from the inner stream is taken in by the outer stream as heat. Therefore, the outer vortex becomes warm and the inner vortex is cooled.

At EXAIR, we have harnessed the cooling power of the vortex tube, and it can be found and utilized in such products as Spot CoolersCabinet Coolers, and Vortex Tubes themselves. If you have questions about Vortex Tubes, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact us.

Brian Farno
Application Engineer


Max Refrigeration vs. Max Cold Temp Vortex Tubes

Here at EXAIR, our vortex tubes are offered in two separate series. The reason for this is to optimize the performance of the cold air temperature drop when operating with opposite ends of the cold fraction chart. The maximum refrigeration vortex tubes, 32xx series, perform optimally when they are set to a greater than 50% cold fraction.  The maximum cold temp vortex tubes, 34xx series, perform optimally when they are set to a less than or equal to 50% cold fraction. The cold fraction is discussed more in-depth within this link from Russ Bowman, Vortex Tube Cold Fractions Explained. This blog is going to explain a little further why one series of vortex tubes would be chosen for an application over another.

Cold Fraction
EXAIR Vortex Tube Performance Chart

Maximum refrigeration (32xx) vortex tubes are the most commonly discussed of the two types when discussing the optimal selection of the vortex tube for an application. The 32xx series vortex tubes achieve a maximum refrigeration output when operated at 100 psig inlet pressure with around  80% cold fraction. This would give a temperature drop from incoming compressed air temperature of 54°F (30°C). The volumetric flow rate of cold air will be 80% of the input flow which means only 20% is being exhausted as warm exhaust air. By keeping the flow rate higher the air is able to cool a higher heat load and is the reason the vortex tube is given a BTU/hr cooling capacity.

Vortex Tube Hot Valve Adjustment

Maximum cold temperature (34xx) tubes are less common as their applications are a little more niche and require a very pinpoint application. Rather than changing the temperature inside of a cooling tunnel or cooling an ultrasonic welding horn, the max cold temp vortex tube is going to have a minimum cold flow rate, less than 50% of input volumetric flow.  This minimal flow will be at temperature drops up to 129°F (71.1°C) from the incoming compressed air temperature.  This air is very cold and at a low flow. A 20% cold fraction exhausts 80% of the input volume as hot air. This type of volume would be ideal for sensor cooling, pinpoint cooling of a slow-moving operation, or thermal testing of small parts.

In the end, EXAIR vortex tubes perform their task of providing cold or hot air without using any refrigerants or moving parts. To learn more about how they work, check out this blog from Russ Bowman. If you want to see how to change the cold fraction, check out the video below. If you would like to discuss anything compressed air related, contact an application engineer, we are always here to help.

Brian Farno
Application Engineer