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Vortex Tube Question

  1. Aug 20, 2011 #1
    Alright guys here is the deal, i have had a vortex cooling system on my mind for a while and started wondering

    could it be made larger, with more air flowing through it, but with less PSI

    and still cool at least somewhat?

    i was thinking of making a larger one and attaching it to a high air flow fan in my dorm, as it would not be against the rules of what we can and cannot have, so that i can cool my room kind of like AC

    i have a standing fan that i could attach a cone to that in its from factory state moves 6500 cfm

    this is the fan i was thinking of using

    so, would this even be possible, even if it would drop the temp by 5 degrees (though preferably more)

    thanks for any answers


    PS: i can clarify anything if needed
  2. jcsd
  3. Aug 21, 2011 #2


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    Hi ENGRstudent. Welcome to the board. Put a control volume around the vortex tube and consider, is there any heat or work crossing the control surface? What does the control volume look like? Put a control volume around just the vortex tube and ignore the fan for a moment. There is some air with some enthalpy coming into the control volume at one location and some air with some enthalpy leaving the control volume in two different locations. Can you write the first law for this control volume? Is there any heat or work crossing the control surface?

    We could also imagine there is something happening within this control volume. There is a transfer of energy between the two discharge streams. A vortex tube is analogous to a device that takes some of the incoming air and expands it (not very efficiently) through one of the two discharge paths. The isentropic efficiency for this path is much less than 100%, probably around 30%. The energy rejected by this discharge path must be put into the second discharge path because of conservation of energy right? Consider that you have to take this warmer air and put it somewhere. Will it go into your dorm room?

    You can also put a control volume around just the fan so you have air going into the fan and leaving the fan with some enthalpy and there is also some electric power entering the CV to run the fan. What does that control volume look like? Again, the isentropic compression of the air is much less than 100% efficient. What happens to the air temperature?

    Try writing the first law for these two CV's and see if that helps at all. Then look at how you can put the two together and see if there's any way you can get cold air into your room.
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