Vortex Tubes and Spot Cooling
Cold air to -50ºF (-46C) from your compressed air supply - with No Moving Parts!
What is A Vortex Tube?
A low cost, reliable, Maintenance Free solution to a variety of industrial spot cooling problems. Using an ordinary sypply of compressed air as a power source, Vortex Tubes create two streams of air, one hot and one cold, with No Moving Parts. Vortex Tubes can produce:
- Temperature from -50º to +260ºF (-46º to +127ºC)
- Flow rates from 1 to 150 SCFM (28 to 4,248 SLPM)
- Refrigeration up to 10,200 Btu/hr (2,570 Kcal/hr)
Temperatures, flows and cooling power are adjustable over a wide range using the control valve on the hot end exhaust.
Why EXAIR Vortex Tubes?
EXAIR Vortex Tubes are construction of stainless steel. The wear resistance of stainless steel, as well as its resistance to corrosion and oxidation, assures that EXAIR Vortex Tubes will provide years of reliable, Maintenance-Free operation.
How A Vortex Tubes Works?
Compressed air, normally 80-100 PSIG (5.5 - 6.9 BAR), is ejected tangentially through a generator into the vortex spin chamber. At up to 1,000,000 RPM, this air stream revolves toward the hot end where some escapes through the control valve. The remaining air, still spinning, is forced back through the center of this outer vortex. The inner stream gives off kinetic energy in the form of heat to the outer stream and exits the vortex tube as cold air. The outer stream exits the opposite end as hot air.
A Phenomenon of Physics
The two questions we’re most often asked about the vortex tube are, “How long has it been around?” and “How does the thing work?” The following is a brief history and theory of the vortex tube.
The vortex tube was invented quite by accident in 1928. George Ranque, a French physics student, was experimenting with a vortex-type pump he had developed when he noticed warm air exhausting from one end, and cold air from the other. Ranque soon forgot about his pump and started a small firm to exploit the commercial potential for this strange device that produced hot and cold air with no moving parts. However, it soon failed and the vortex tube slipped into obscurity until 1945 when Rudolph Hilsch, a German physicist, published a widely read scientific paper on the device.
Much earlier, the great nineteenth century physicist, James Clerk Maxwell, postulated that since heat involves the movement of molecules, we might someday be able to get hot and cold air from the same device with the help of a “friendly little demon” who would sort out and separate the hot and cold molecules of air.
Thus, the vortex tube has been variously known as the “Ranque Vortex Tube”, the “Hilsch Tube”, the “Ranque-Hilsch Tube”, and “Maxwell’s Demon”. By any name, it has in recent years gained acceptance as a simple, reliable and low cost answer to a wide variety of industrial spot cooling problems.
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 these two airstreams are 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.
Theories abound regarding the dynamics of a vortex tube. Here is one widely accepted explanation of the phenomenon:
Compressed air is supplied to the vortex tube and passes through nozzles that are tangent to an internal counterbore. These nozzles set the air in a vortex motion. This spinning stream of air turns 90° and passes down the hot tube in the form of a spinning shell, similar to a tornado. A valve at one end of the tube allows some of the warmed air to escape. What does not escape, heads back down the tube as a second vortex inside the low-pressure area of the larger vortex. This inner vortex loses heat and exhausts through the other end as cold air.
While one airstream moves up the tube and the other down it, both rotate in the same direction at the same angular velocity. That is, a particle in the inner stream completes one rotation in the same amount of time as a particle in the outer stream. However, because of the principle of conservation of angular momentum, the rotational speed of the smaller vortex might be expected to increase. (The conservation principle is demonstrated by spinning skaters who can slow or speed up their spin by extending or drawing in their arms.) But in the vortex tube, the speed of the inner vortex remains the same. Angular momentum has been lost from the inner vortex. The energy that is lost shows up as heat in the outer vortex. Thus the outer vortex becomes warm, and the inner vortex is cooled.
- Cooling electroni controls
- Cooling machining operations
- Cooling CCTV cameras
- Setting hot melts
- Cooling soldered parts
- Cooling gas samples
- Electronic component cooling
- Cooling heat seals
- Cooling environmental chambers
- No Moving Pasrts
- No electricity or chemicals
- Small, lightweight
- Low cost
- Maintenance free
- Instant cold air
- Durable - stainless steel
- Adjustable temperature
- Interchangeable generators
Here are some sample applications:
A Model 3225 Vortex Tube keeps plastic diswasher arms cool during ultrasonic welding.
Special High Temperature Vortex Tubes keep a boroscope lens cool while inserted into a 1200ºF (650ºC) boiler porthole.
A pair of medium Vortex Tubes cool a solenoid coil after a welding operation.
(4) Model 3250 Vortex Tubes cool the cutting knives in this pelletizer to prevent irregular shapes.
(4) Model 3225 Vortex Tubes were positioned to cool the critical corner areas just prior to forming the plastic sheet. By cooling these areas, less stretching of the plastic occurred which resulted in thicker corners.
(2) Model 3250 Vortex Tubes were mounted to the cooling rack and connected to a compressed air line. Cold air produced by the vortex tubes was circulated inside the fuel tanks. Cooling time was reduced from three minutes to two minutes for each tank, improving productivity by 33%.
A Model 3215 Vortex Tube was used to direct cold air at the jaw of the welder. The cooling was transferred through the metal jaw to the tube seam while in the clamped position. Process time was reduced and rejected tubes were eliminated.
(2) Model 3230 Vortex Tubes (with cold air muffler installed) were used to blow cold air on the parts after the brazing cycle. The vortex tubes were set at an 80% cold airflow (cold fraction) to produce maximum refrigeration. The parts were cooled from brazing temperature of 1,450°F (788°C) to handling temperature of 120°F (49°C) within 20 seconds, allowing the machine to operate at its maximum production rate.
- Adjustable Spot Cooler, cold air to -30ºF (-34ºC) from your compressed air supply for spot cooling!
- Mini Cooler, cool small parts and tools with clean, cold air! Prevent burning, melting or breakage!
- Cold Gun Aircoolant, replace messy mist systems - improve dry machining with clean, cold air!
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