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Vacuum+Water= cooling maybe?

  1. Aug 28, 2011 #1
    Vacuum+Water= cooling.. maybe??

    hello everyone

    first I would thank you for this wonderfull forum
    I was only reading for along time and learned a lot.
    today i would like to present an idea about vacuum cooling or evaporative cooling i dont know
    so here it is:
    1) vacuuming the air from a thermally insulated tank half full of water (distelled)

    2) evaporation rate will increase

    3) the tank is now full of water and water vapor

    4) each gram of water will need 540 calories to evaporate which means it will decrease the temparature of 540 grams of water by one degee C

    5) now take out the water vapor by the vacuum pump to a small HX, let condense,release
    the heat then return it back to the tank

    6) we can use a set of coils, a water pump and fan to cool the house.

    here is a pic of this idea hope it helps:

    could it work??
    thank you in advance for any help
    Last edited by a moderator: Apr 26, 2017
  2. jcsd
  3. Aug 28, 2011 #2


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    Staff: Mentor

    Re: Vacuum+Water= cooling.. maybe??

    Yes, it certainly could work. Could it be more efficient than a normal air conditioner? Probably not.
  4. Aug 29, 2011 #3
    Vacuum+Water= cooling.. maybe??

    thank god it is "probably".:biggrin:
    I am relying on one or two improvements to boost efficiency or "COP"
    one is to use the vacuum resulting from the condensing vapor in the heat exchanger
    to pull water vapor from the tank without further use of vacuum pump.

    I know when an idea is so simple and not used, 99% of the time I am missing something
    but I will try to make it with my friend this week, and post the results here.

    Last edited: Aug 29, 2011
  5. Aug 29, 2011 #4


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    Staff: Mentor

    I suggest you clearly define your states and processes so you can use thermodynamics to predict the performance before the test.
  6. Aug 29, 2011 #5
    Re: Vacuum+Water= cooling.. maybe??

    It is not a new idea, http://research.atsfry.com/Passenger/pass_ac.htm [Broken]
    but one worth looking at. The real savings might come form the high duty cycle low startup energy. The return path of the chilled water should be sprayed back into the bath, as this maximizes surface area.
    Last edited by a moderator: May 5, 2017
  7. Aug 29, 2011 #6
    Re: Vacuum+Water= cooling.. maybe??

    Looks like an over complicated cooling tower and industrial air washer to me.

    But hey I am just the guy that has to fix this stuff when it breaks.

    Your most efficient heat transfer occurs at phase (state) change. Where are you changing state and what kind of temps are we talking about?
  8. Aug 29, 2011 #7
    Re: Vacuum+Water= cooling.. maybe??

    Sorry. Just re-read the post and realized your phase changes.
  9. Aug 29, 2011 #8
    Re: Vacuum+Water= cooling.. maybe??

    thank you john for the link, but it is too complicated than what i have in mind
    spraying the feed water is a good idea
    by the way does this arrangement has a name to google it ?
  10. Aug 29, 2011 #9


    User Avatar
    Science Advisor

    Re: Vacuum+Water= cooling.. maybe??

    Neat idea, but as Russ says, probably not going to be more efficient than an AC (particularly in the creation of the vacuum), or as easy to make as a DIY swamp cooler (block of ice / mister in front of a fan).

    On a somewhat tangential note, I saw a Zeer (pot-in-pot refrigerator) a few years back on a tv program--evaporative cooling for small-scale refrigeration, and IMO incredibly useful in the third world:
  11. Aug 30, 2011 #10
    Re: Vacuum+Water= cooling.. maybe??

    I think the most common name would be "steam jet refrigeration" From My understanding it was used a lot in the 1930s for theater AC systems. Any place that had a boiler, could use the steam to cool as well.
    As to the efficiency, any time you can use heat in it's native form to do your work, you have saved several inefficient steps.
    I also found this better link.
    I think the main issue with this technology, was that it did not scale well.
    Another thing to look at for reference only is how airlines chill the cabin air.
    Comperssion(in the jet engine), radiate the heat to the outside, and expand into the cabin(with those little nozzles over the seats.)
  12. Aug 31, 2011 #11
    Re: Vacuum+Water= cooling.. maybe??

    I think the key part is the pump in it ...Is it?
  13. Aug 31, 2011 #12
    Re: Vacuum+Water= cooling.. maybe??

    A piezo pumps will help SCALE IT VERY WELL .I hv seen the similar pumps from some webs like:www.takasago-elec.com[/url] , [url]http://www.piezodata.com[/URL] ,
    [url]http://waterpumpsz.com/2675-micro-water-pumps.html[/url] , I think u can find one suitalbe for yr work .
    Last edited by a moderator: Apr 26, 2017
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