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Vortex tube application question

  1. Apr 17, 2007 #1
    I recently invented a new application for vortex tube.

    The application requires a very minimal flow of air at freezing temperature.

    I wonder if it's possible to design a vortex tube at a very small size if only a very tiny air flow is required? Is flow rate proportional to physical size of the vortex tube?

    How about cost? Is it possible to mass produce vortex tube for $20 or less?

  2. jcsd
  3. Apr 17, 2007 #2


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    Hi paul,
    You didn't say how small you wanted to make this vortex tube, but in principal, I don't see any reason you couldn't make it quite small. The lower flow rate will of course simply reduce the amount of 'refrigeration' you can obtain from the flow.

    The only problem I see is heat transfer along the axial direction of the tube, but I have a hard time believing that would be very signficant, even using a highly thermally conductive material, because gas velocity is so high. If it turned out to be an issue, you could use a plastic which has a much lower thermal conductivity than metals.

    As for mass producing them, if you made something on the order of a hundred or more, I suspect even a machined part could be brought under $20. Doing tens of thousands at a time might lend itself to a molded design in plastic and costs on the order of a few bucks or less.
  4. Apr 17, 2007 #3
    Thanks a lot for the help.

    I heard vortex tube only requires compressed gas as small as 80 psi. If the device is to be powered by an air tank, the air tank can be refilled at a gas station right?

    Is the output cold air at atmospheric (ambient) pressure? Can flow rate be adjusted? Thanks.

    I'm really interested in the vortex tube for my application but I'm new to them.
    I appreciate your help.
  5. Apr 18, 2007 #4


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    of course


    They generally have adjustments to change the split of the flow, such that some range of flow can go to one side, the remainder to the other.
  6. Apr 19, 2007 #5
    Wow, it's nice to know the vortex tube can be made out of plastic. Can plastic ones perform just as good as the metal ones?

    My application involves a vortex tube powered by a small air tank. The whole system is designed to be portable. It's important that the amount of air be used as efficiently as possible so that refills are not needed as often.

    For the application I'm doing, I only need a very small cooling capacity, so only a very low air flow rate is required.

    Is it possible to size/design the vortex tube so that the output flow is controlled to just the amount I need (for a given PSI air), so that it doesn't use up air too quickly and unnecessarily.

    What I'm trying to ask is for a source of air at a given pressure, is the output air flow rate (hot air plus cold air) independent of the vortex tube or can the design of the vortex tube alter the rate at which the air get used? I heard there something called a "generator" that serves this function?

  7. May 2, 2007 #6
    Drawings of the vortex tube profile required

    Heloo Guys Can some one provide vortex tube profile ...It would be gretaly apriciated if the drawing is provided with all pertaing deatils .You can also mail me on CaddPro@hotmail.com

  8. May 11, 2007 #7
    The vortex tube air rate can be controlled by a standard variable air regulator. The smallest tube I have used is about 6 inches long and 5/8" diameter. The hot air is vented and the cold introduced to the place to be cooled. 30 lbs of air pressure is enough to operate the device. They use quite a lot of air for the amount of cooling gain. But beat a refrigeration compressor for portability. Use really good insulation to hold your cool.
  9. Jun 6, 2007 #8
    hello guys,

    I know that vortex tube requires air as motive fluid, is it possible to use water or some other liquid as motive fluid? If not, why not??
    Any scientific explanation??
  10. Jun 13, 2007 #9


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    To the last poster: well you could use other kinds of
    fluids, but I believe it's much easier with a gas because
    the thermal conductivity of a gas is quite low compared
    to most liquids, and because the gas can easily be made
    to flow at high speeds / vorticities with low drag and
    low friction. I believe those characteristics of gas vs.
    liquids make the gas possibility much more practical
    than the liquid one. It'd be interesting to study
    the possibilities sciendifically, though.

    To the original poster:

    I'd think the air consumption rate would make a vortex
    tube sourced with compressed air from a small portable
    tank impractical. Even a large SCUBA tank at exceedingly
    high pressure only holds 100 cubic feet of air relative to
    atmospheric pressure. A small 175 PSI "5 gallon" tank
    that you could refill at a service station holds even less
    cubic feet. I don't know if you're talking about very
    tiny dimensions (a few millimeters) here which might
    consume only fractional parts of 1 CFM of air flow, but
    for anything of a small but respectable size, you'll only
    have minutes of cooling given the air supply.

    IMHO I estimate that you'd be better off using a
    straight SCUBA tank and expansion valve to create
    freezing air straight from the expansion of the highly
    compressed gases rather than trying to use a vortex tube
    which would probably use more air for less cooling.

    Even a 100-175PSI small tank of compressed cool or
    ambient temperature air may perhaps be more
    effectively used in cooling by simple expansion rather
    than via a vortex tube, though I'm sure there are some
    regimes of operation in which the vortex tube is

    Another option that's inexpensive enough for use in
    consumer electronics (portable DC powered beverage
    coolers) is the peltier cooler which is a thermoelectric
    device that can easily produce small areas of freezing
    temperatures (given a stack of perhaps 2 junctions)
    given something like a dozen watts of applied power,
    though of course you'll have to efficiently dissipate
    the waste heat from the other side of the device to the
    ambient air to realize a cooling benefit from 'the cold side'
    of the device.

    Beyond these approaches, it's quite common to have
    small sterling cycle coolers or other such refriigeration
    devices that are even more efficient and
    use electrically powered tiny motors/pumps for
    specialized cooling of small areas, though usually they're
    only either very expensive specialty items in limited
    production or are produced in somewhat larger
    numbers but only for specialty applications like their use
    in thermal cameras so they're not so commonly available
    as an "off the shelf" part. They're not so complex though
    that they couldn't be produced cheaply in quantity given
    sufficient funds to create the custom designed mechanism
    in the first place.

    The vortex tube is probably an OK idea though if you have
    a larger capacity of compressed airflow available, though,
    but, again, if the compressed air is at cool or ambient
    temperatures to begin with, just expanding it from
    a proper nozzle may produce all the cooling needed
    without needing the vortex tube.
  11. Feb 17, 2008 #10
    Locating inexpensive vortex tubes

    Hello. I came across this old thread and want to know if you or anyone here has been able to locate inexpensive vortex tubes. Most websites sell them for over $100 (metal) for the smallest 2 CFM models. Someone here also mentioned you could possibly use a plastic vortex tube but I have been unable to find any companies that make or sell them on the internet.

    I would preferably like to a metal one as its conductive properties are much higher than that of plastic, however I believe a plastic one would also work for my needs as I don't need such drastic variantions in the temperatures produced.

    I was hoping to find one under $40-50 or even cheaper. Can anyone recommend where to find vortex, plastic or metal, for under this price?

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