Category: Vortex Tubes

Rudolf Hilsch and How the Ranque-Hilsch Vortex Tube Came To Be

Published on by Jordan T ShouseLeave a comment

The exact beginnings of the device remain unclear. It is believed that a French inventor, Georges Ranque, stumbled upon the principle and abandoned some initial prototypes in the wake of the German Army during France’s occupation. These prototypes caught the attention of Rudolf Hilsch, a German physicist engaged in developing low-temperature refrigeration systems for the war effort. Hilsch enhanced the original design but discovered that it did not outperform traditional refrigeration techniques in reaching relatively low temperatures. Eventually, the device became recognized as the Hilsch tube.

The Original drawing from Rudolf Hilsche’s 1947 Publication.

The Hilsch tube was assembled using a pair of modified nuts along with various other components. The horizontal section of the T-shaped fitting features a uniquely machined element that fits snugly within the arm. This element has a spiral cross-section on the inside, contrasting with its outer shape. At the “step” of the spiral, there is a small opening that connects to the T’s leg. When air enters through the leg, it exits through this opening and spirals around the one-turn design. The “hot” pipe measured approximately 14 inches in length and had a half-inch internal diameter. Its far end is equipped with a stopcock to regulate the system’s pressure. Meanwhile, the “cold” pipe is about four inches long, also with a half-inch internal diameter. The end that connects to the spiral piece has a washer with a central hole of around a quarter of an inch in diameter. Additionally, washers with varying hole sizes can be used to fine-tune the system.

With EXAIR’s vortex tube, compressed air is supplied into the tube where it passes through a set of nozzles that are tangent to the internal counter-bore. The design of the nozzles forces the air to spin in a vortex motion at speeds up to 1,000,000 RPM. The spinning air turns 90° where a valve at one end allows some warmed air to escape. What does not escape, heads back down the tube into the inner stream where it loses heat and exhausts through the other end as cold air.

How a Vortex Tube Works

Both streams rotate in the same direction and at the same angular velocity. Due to the principle of conservation of angular momentum, the rotational speed of the inner vortex should increase. However, that’s not the case with the Vortex Tube. The best way to illustrate this is with Olympic Figure Skating. As the skater is wider, the spinning motion is much slower. As she decreases her overall radius, the velocity picks up dramatically and she spins much quicker. In a Vortex Tube, the speed of the inner vortex remains the same as it has lost angular momentum. The energy that is lost in this process is given off in the form of heat that has been exhausted from the hot side of the tube. This loss of heat allows the inner vortex to be cooled, where it can be ducted and applied for a variety of industrial applications.

This Vortex Tube theory is utilized in basic Vortex Tubes, along with a variety of other products that have additional features specific for your application. EXAIR’s line of Cabinet Coolers, Cold Guns, Adjustable Spot Coolers, Mini Coolers, and Vortex Tubes all operate off of this same principle.

Image
Image

EXAIR HazLoc Cabinet Cooler Systems provide safe and reliable

If you’re fascinated by this product and want to give it a try, EXAIR offers an unconditional 30-day guarantee. We have them all in stock and ready to ship as well, the same day with an order received by 2:00 ET. Feel free to get in contact with us if you’d like to discuss how a vortex-based product could help you in your processes.

Jordan Shouse
Application Engineer

Send me an Email
Find us on the Web 
Like us on Facebook
Twitter: @EXAIR_JS

Rudolf Hilsche’s Publication Drawing provided by Die Zeitschrift für Naturforschung

(Photo Link https://zfn.mpdl.mpg.de/data/1/ZfN-1946-1-0208.pdf )

Video Blog: The Effects of Back Pressure On A Vortex Tube

Published on by Brian FarnoLeave a comment

The video below is one that I have explained to customers countless times over my tenure here at EXAIR. Vortex Tubes are most efficient when discharging the cold and hot air streams into atmospheric conditions. This video is my attempt to showcase just how much it will affect your performance when a restriction on the discharge cannot be avoided.

If you would like to discuss Vortex Tubes and their feasibility in your application, feel free to contact an Application Engineer today!

Brian Farno, MBA – CCASS Application Engineer

BrianFarno@EXAIR.com
@EXAIR_BF

EXAIR’s Cold Gun Promotion

Published on by Al Wooffitt1 Comment

It’s that time of year again for EXAIR‘s Cold Gun Promotion (online only). From November 1st 2024 through to the end of the year, you can receive a Dual Point Hose Kit for free with the purchase of our promotional Cold Gun System w/ Single Point Hose Kit or promotional High Power Cold Gun System w/ Single Point Hose Kit. These hose kits come with standard point tips or 1″ fan tips. The dual point kit gives you the ability to provide cooling to more than one side of large diameter cutters and components that need cooling.

Cold Guns Systems

So, what’s so great about EXAIR’s Cold Gun? If you’re looking for a way to extend the life of your tools by keeping them cool without the mess that can be left when using a coolant, then our Cold Gun is the perfect solution. When supplied with a source of compressed air, the Cold Gun and High Power Cold Gun produces a stream of clean, cold air that is 50°F below your compressed air supply temperature. In addition to this, the Cold Gun is very quiet at only 70dBA and has no moving parts to wear out. Just supply it with clean, dry compressed air, and it will run maintenance free for many years!

With a magnetic base, the Cold Gun is easy to install and mount. The Cold Gun is an ideal alternative to messy and expensive coolant mist systems. It eliminates the cost of purchase and disposal of cutting fluids as well as worker related health problems from breathing airborne coolant or slipping on wet floors. Replacing a coolant-based system also eliminates the need for secondary cleaning operations after milling or drilling.

If you would like to discuss how an EXAIR Cold Gun can help you with your coolant application, then give us a call!

Al Wooffitt
Application Engineer

Send me an Email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_AW

Controlling Temperature And Flow From A Vortex Tube

Published on by Russ BowmanLeave a comment

The Vortex Tube is among the most fascinating air-operated devices to me. It’s right up there with the pneumatic impact wrench, which is my HIGHLY preferred method of removing (and replacing) a tire on a vehicle. While there are several different types of impact wrenches, they all basically use air pressure to move internal parts in a manner in which they strike (or impact) a rotating element with a socket on the end, resulting in a lot more torque being applied than if it was simply spinning a propeller attached to the shaft.

Vortex Tubes, on the other hand, all work on the same principle, discovered by a French engineer, Georges Ranque, while he was experimenting with a new design of a vacuum pump in 1922. There doesn’t seem to be any record of him completing the work on his newfangled vacuum pump, but he did continue experimenting with this device that made hot air come out one end, and cold air come out the other, getting a patent for it in 1931.

How a Vortex Tube Works: compressed air enters the vortex spin chamber (big blue arrow from above left), where the Generator imparts a spinning motion to it (red ribbon, moving to the right). When the spinning air flow reaches the other end, some of it is forced to change direction and, while still spinning, flow the other way (blue ribbon, moving to the left). The rest exits through the hot valve (represented by the yellow cone). When the spinning air flow changes directions, it gives off energy in the form of heat, causing hot air to exit one way, and cold air to exit the other.

EXAIR offers two series of Vortex Tubes:

  • 32XX series, or Maximum Refrigeration. These make the highest flows of cold air, at temperatures suitable for rapid cooling of warm objects to ambient (or below) temperatures.
  • 34XX series, or Maximum Cold Temperature. These will give you the coldest air possible – as low as minus 50°F – but at lower flows, relative to the 32XX series. I’ll go into more detail on both of these in a minute.
Sub-zero air flow from Model 3408 Vortex Tubes cools & solidifies chocolate in candy molds.

Both of these series consist of Vortex Tubes in three sizes, with multiple models in each size. The difference between the models in each series is the compressed air consumption:

You can control the temperature, and the flows (both hot and cold), of any Vortex Tube in a few different ways:

  • Supply pressure affects the total flow of the two air streams, and the magnitude of the change in temperature. Since higher pressure equals more energy, it stands to reason that, at higher pressures, the hot air will be hotter, and the cold air will be colder.
  • Cold Fraction is the percentage of the compressed air supply that gets directed to the cold end. You can get VERY cold air from a Vortex Tube by setting it to a low cold fraction. This is done by opening the Hot Valve to let more hot air out. That causes the flow rate, and the temperature of the air coming out of the cold end, to drop.
Turning the Hot Valve counterclockwise (blue arrow) lets more hot air out, which lowers the cold air flow, and temperature. Turning it clockwise (red arrow) lets less hot air out, which raises the cold air flow…and temperature.
  • Two types of Generators can be installed in an EXAIR Vortex Tube – these are what determine the series I mentioned above:
    • Type “R” (Maximum Refrigeration) Generators allow for Cold Fraction adjustments from 50-80%. With an air supply pressure of 100psig, the cold air will be 54°F (when set to an 80% Cold Fraction) to 100°F (at a 50% Cold Fraction) lower than the compressed air supply temperature. This makes them suitable for applications where rapid cooling of an object is needed.
    • Type “C” (Maximum Cold Temperature) Generators give you Cold Fraction adjustments from 20-50%. A Vortex Tube with a “C” Generator installed will give you the same 100°F temperature drop as the “R” Generator will at a 50% Cold Fraction, but at a 20% Cold Fraction, it’ll be 123°F colder than the supply. These are used where cooling to temperatures below 0°F is needed.
How to tell which Generator is installed in a Vortex Tube.

If you need to remove & replace a tire, I strongly recommend using a pneumatic impact wrench. If you need to blow cold air for something, I just as strongly recommend using an EXAIR Vortex Tube. Different applications require different series, models, and settings. Give me a call if you’d like to find out which combination of those is right for your application.

Russ Bowman, CCASS

Application Engineer
Visit us on the Web
Follow me on Twitter
Like us on Facebook