Vortex heating and cooling
A device using high pressure air to create to both heat and coolIf you take a normal air compressor air outlet nozzle and hold it between you fingers and try to restrict the air flow you will notice the pressurised air become hot and you will not be able to stand to hold it for long.In this device air is forced through the centre potion of this gun and air flow is restricted in one end byadjustable screw at one end producing extreme heat whilst at the other end cool air is produced.
The placement of the air flow in the centre is critical and some practice and experimentation may be needed to get this device to work.This device has been incorporated in air conditioning system but found not to be efficient compared to othermethods at present. An interesting device never the less
MORE ON THE VORTEX online article
Vortex Tube Phenomenon
The vortex tube was discovered in 1930 by French physicist Georges Ranque. Vortec was the first company to develop this phenomenon into practical, effective cooling solutions for industrial applications. Here's how it works.
Fluid that rotates about an axis -- like a tornado -- is called a vortex. A vortex tube creates a vortex from compressed air and separates it into two air streams -- one hot and one cold. Compressed air enters a cylindrical generator which is proportionately larger than the hot (long) tube where it causes the air to rotate.
Then, the rotating air is forced down the inner walls of the hot tube at speeds reaching 1,000,000 rpm. At the end of the hot tube, a small portion of this air exits through a needle valve as hot air exhaust.
The remaining air is forced back through the center of the incoming air stream at a slower speed. The heat in the slower moving air is transferred to the faster moving incoming air. This super-cooled air flows through the center of the generator and exits through the cold air exhaust port.
I read about the Hilsch Vortex Tubes when I was in the 7'th grade. That would have been about 28 years ago!! It was in a book titled 'The Scientific American Book of Experiments For the Amateur Scientist'. I must have checked that book out a hundres times! I told my dad "This thing could have some neat uses... spot cooling or something else in industry". Now, of course there is a mature industry surrounding that device(Vortec). I guess they can't really have too many rights on the basic tube... it is 60 years old!
Vortex tubes make use of a kind of Maxwell's Demon. Compressed air is spiralled into the side of a tube and made to wrap into a tight spin. The molocules spinning in the inner part of the spiral have less kinetic energy than those flying around in the outside (larger diameter). There is a small hole in the COLD end that lets the slower molocules out. The seperation of flow is controlled by valve the end of the tube. More than 100 degrees temperature delta is possible.
They DO require a large amount of compressed air to work. When mechanical refrigeration came available it went away.
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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?". Following is a brief history and theory of the product.
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 thru 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.
