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 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.
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.
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
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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 )
