The two questions most often asked about the vortex tube are, "How long has it been around?" and "How does it work?"
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 air and cold air with no moving parts. However, it soon failed and the vortex tube slipped into obscurity until 1945 when Rudolf Hilsch, a German physicist, published a widely read scientific paper on the device.
Much earlier, the great 19th century physicist, James Maxwell postulated that since heat involves the movement of particles, we someday might be able to get hot and cold air from the same device with a little 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 tube, the Hilsch tube and the 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.
Theories abound regarding the dynamics of a vortex tube. While this does not explain why it works - it does explain the path followed by the air:
Operation
Compressed air is supplied to the vortex tube and passes through nozzles that are tangent to an internal counter bore. These nozzles set the air in a vortex motion. This spinning stream of air turns spirals 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, with the remaining air heading back up the tube as a second vortex inside the low-pressure area of the larger vortex. This inner vortex loses heat to the outer vortex, and exhausts through the other end as cold air.
Cold air at minus 46°C - with no moving parts
With the Exair vortex tube, customers now have a low cost, reliable, maintenance free solution to a variety of industrial spot cooling problems. Using an ordinary supply of compressed air as a power source, the Exair vortex tube creates two streams of air, one hot and one cold, with no moving parts.
The Exair vortex tube can produce:
* Temperatures from -46 to +127°C.
* Flow rates from 14,6 to 2 188 kg/minute.
* Refrigeration up to 10 200 Btu/hr.
Temperatures, flows and refrigeration are adjustable over a wide range using the control valve on the hot end exhaust. Exair vortex tubes are constructed of stainless steel. The wear resistance of stainless steel, as well as its resistance to corrosion and oxidation, assures that the tubes will provide years of reliable, maintenance free operation.
Cold air and temperature, are easily controlled by adjusting the slotted valve in the hot air outlet. Opening the valve reduces the cold airflow and cold air temperature. Closing the valve increases the cold air flow and the cold air temperature. The percentage of the air directed to the cold outlet of the tube is called the 'cold fraction'. In most applications, a cold fraction of 80% produces a combination of cold flow rate and temperature drop that maximises refrigeration, or Btu/hr. output of an Exair vortex tube. While low cold fractions (less than 50%) produce lowest temperatures, cold airflow is sacrificed to achieve them.
Most industrial applications ie, process cooling, part cooling, chamber cooling, require maximum refrigeration utilise the 3200 series of Exair vortex tubes, certain 'cryogenic' application ie, cooling lab samples, circuit testing, are best served by the 3400 series of Exair vortex tubes.
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