Field of the Invention
Embodiments of the invention relate to vortex tubes. More specifically, embodiments of the invention relate to vortex tubes having an arcuate hot leg.
Background
The vortex tube was invented in 1933 by French physicist George Ranque and improved in 1947 by Rudolph Hilsch. Thus, vortex tubes are also known as the Ranque-Hilsch vortex tube. In general, a vortex tube is a mechanical device that separates compressed fluid into hot and cold air streams. It has no moving parts, and does not rely on electricity or chlorofluorocarbons etc. to achieve the temperature separation. Vortex tubes are commonly used in spot cooling applications.
Fluid that rotates about an axis in a cyclonic effect 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. The compressed air is injected into a cylinder perpendicular to the longitudinal axis. The cylinder (also referred to as a vortex chamber) is proportionally larger in diameter than either the hot leg (which is the long leg) or the cold leg (the short leg) and both legs are generally coaxial and collinear with the vortex chamber.
The injection of air into the vortex chamber causes it to rotate at high speed. When the rotating air is forced down the inner walls of the hot leg at the distal end a small portion of the air exits through a valve as the hot air stream. The remaining air is forced back through the center of the incoming stream at a slower speed. The heat in the slow moving air is transferred to the faster moving air traveling down the outer portions of the tube thus resulting in a cool airstream which passes back through the center of the vortex chamber and out the cold leg through a cold air exhaust port. In general, the longer (up to about 0.5 meters) the hot leg the greater the temperature separation, that is the difference in temperature between the hot stream and the cold stream. Unfortunately, in many applications, the such long legs would make the use of the vortex tube impractical. As a result, many commercial vortex tubes have relatively short hot legs and suffer from reduced cooling capabilities.
Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that different references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.
Cold leg 106 is also coupled through mixer 120. Mixer 120 controls the relative portions of hot and cold air flowing out the outlet port 112 by virtue of, for example, splitter 122 internally to blocks or allows to pass more or less of the respective streams that enter the mixer 120. In one embodiment, splitter 122 permits a mixture of cold and hot from entirely cold to entirely hot. The mixer 120 directs a portion of the air to the outlet port 112 and the remainder to an exhaust port 128. Flow from the exhaust port 128 is controlled by exhaust valve 126. Exhaust valve 126 may be a ball valve, needle valve, check valve or any valve suitable for controlling fluid flow. The exhaust valve is designed to provide cold mass fraction in the range of 0.2 to 0.9. That is 20% to 90% of the exhausted airstreams (that is the aggregate of the stream from the exhaust valve 126 and the stream from outlet port 112) is sourced from the cold leg 106. The exhaust port 128 is positioned on the assembly 100 to point away from a user when used for personnel cooling applications.
An inlet port 116 permits the introduction of compressed air perpendicularly to a long axis of the vortex chamber 104. It is desirable to have the inlet port 116 centered relative to the vortex chamber 104. In the figure, the inlet port 116 is shown as threaded. This threading may receive a nozzle (not shown) to permit coupling to a compresses air source. In some embodiments, the inlet port 116 accommodates nozzles having an internal diameter of 10-15 mm. A vortex inducer (not shown in this figure) is disposed within the vortex chamber 104. The vortex inducer has vanes that encourage the compressed air flowing in through the inlet port 116 to form a vortex and travel down the hot leg 102.
By using an arcuate (bent) hot leg 102, the length of the hot leg (and therefore the temperature separation) can be increased while significantly reducing the long dimension of the vortex tube assembly 100. In this U-shaped example, the long dimension of the assembly 100 is approximately half the linear length of the hot leg 102. For embodiments intended for personal use, hot legs having a liner dimension of 300-400 mm are suitable. With this dimension, and a diameter to length ratio of 30-40 (implies a diameter of approximately 10 mm) temperature separations of 80 degrees Celsius are obtainable. While
The hot air passing through the outlet orifices enters a hot air antechamber 224, which provides a conduit to the mixer 120. Similarly, the outlet orifice of the cold leg 106 is in fluid communication with a cold antechamber 226 that provides a conduit for the cold air stream to the mixer 120. The cold orifice is generally positioned centrally in a terminal wall of the cold leg 106. The percentage of cold outlet orifice diameter to minimum hot leg diameter is generally in the range of 40%-70%.
An important parameter in the design of the vortex tube is the length to diameter ratio. Generally, as noted above, the longer the hot leg, the better but the length diameter ration should exceed 10 and 25 to 35 is preferred. In general, a range of 10-50 for the length to diameter ratio yields suitable results. It has been found that ratios greater than 55 and/or lengths greater than 1 meter provide no additional benefit. For purposes of the length to diameter calculation the minimum diameter along the hot leg is selected. In one embodiment, the length of the hot leg is in the range of 300-400 mm with an initial diameter of 9.5 mm increasing to 14.6 mm at the bend. The taper angle is 1.5° per side for a 3° taper along its length. With a hot leg of this length, the assembly has a maximum long dimension less than 225 mm.
In one embodiment, the vortex tube assembly may be molded in two halves from a suitable thermoplastic. The plastic must be appropriately selected to withstand the pressure and temperature ranges expected to be encountered during use. For example, Acetal has been found to have suitable properties but other thermoset plastics, thermoform plastics or metal could be used. The two halves may then be for example heat welded together. In some embodiments, the cover can be integrally molded with the underlying halves of the vortex tube.
In the foregoing specification, the embodiments of the invention have been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
This application is a divisional of pending U.S. patent application Ser. No. 13/669,347 filed Nov. 5, 2012 entitled “CURVED VORTEX TUBE”
Number | Name | Date | Kind |
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1952281 | Georges | Mar 1934 | A |
2819590 | Green | Jan 1958 | A |
2893214 | Hendal | Jul 1959 | A |
3103104 | Shackson | Sep 1963 | A |
3630039 | Hayashi | Dec 1971 | A |
3898978 | Marcus | Aug 1975 | A |
4914752 | Hinson | Apr 1990 | A |
5027807 | Wise | Jul 1991 | A |
9599372 | Bancroft | Mar 2017 | B2 |
20080029624 | Shkolnikov | Feb 2008 | A1 |
20140116429 | Patil | May 2014 | A1 |
20190175959 | Brose | Jun 2019 | A1 |
Number | Date | Country |
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2923722 | Apr 2012 | FR |
Number | Date | Country | |
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20170151450 A1 | Jun 2017 | US |
Number | Date | Country | |
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Parent | 13669347 | Nov 2012 | US |
Child | 15423894 | US |