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Further cooling evaporative cooled air... would this work?

  1. Jun 6, 2017 #1
    Evaporative cooling is pretty cold, but I wonder how effective the following would be at chilling the air even further, even if not very energy efficient with having to freeze ice, additional air pump, etc. I was thinking that since the air in the air chamber was cooled, the ice would melt at a much slower rate. I imagine the air pump would not be able to move the air as quickly as the fan pulls it in, too.. Any educated thoughts on this?

    Thanks COLDAIR.png
     
    Last edited: Jun 6, 2017
  2. jcsd
  3. Jun 6, 2017 #2

    russ_watters

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    Could you explain the process after the evaporative cooler please. It isn't clear to me what is happening. Are you pumping air through the coil and cooling it with ice water?
     
  4. Jun 6, 2017 #3
    Sorry. Yes, that is exactly right. I haven't tried, nor do I have any idea if it would work, effectively.
     
  5. Jun 6, 2017 #4

    russ_watters

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    Well, it's exactly the opposite of how a normal air conditioner works. Since the water has a higher energy density, you need a lower volume of it than you need of air for proper heat exchange. Besides which, compression of the air brings energy losses. So the best way to do it is the normal way: run the cold water through the coil and blow the air across it with a normal fan.
     
  6. Jun 6, 2017 #5
    Interesting!! Thank you so much.
     
  7. Jun 14, 2017 #6

    rbelli1

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    You also have to consider the amount of water you are putting in the air with your evaporative cooling. The air being very high humidity produces a large amount of heat when cooled due to condensation.

    BoB
     
  8. Jun 14, 2017 #7
    Thank you for the information. Where I live the air is dry and hot. I plan to test different pad thicknesses, and levels of water saturation to see which combination offers the greatest cooling effect.
     
  9. Jun 14, 2017 #8

    russ_watters

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    By the way, I didn't comment on your overall concept before, but in hot and dry climates, air conditioners (particularly ones that need to be 100% outside air) do indeed use this exact method of two-stage cooling. I've even seen indirect evaporative cooling (adds the humidity to the exhaust, not the supply airstream) used in the northeastern US.
     
  10. Jun 14, 2017 #9

    rbelli1

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    This is possibly off topic but what necessitated the need for 100% outside air?

    BoB
     
  11. Jun 14, 2017 #10

    russ_watters

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    Laboratory and industrial ventilation mostly. High occupancy or exhaust driven spaces like commercial cafeterias/kitchens may also have it.

    And, of course, when the air outside is cooler/drier than the air inside you can use part time "economize mode" or full time evaporative cooling.
     
    Last edited: Jun 15, 2017
  12. Jun 14, 2017 #11
    Having lived in the desert in the past, I've learned that new wood-shaving pads in an evap. cooler don't work very well the first season. After they have aged and been thru a few dust or sand storms they are substantially improved. When new, you get quite high humidity in the building and only so-so cooling, subsequent seasons they work fine but slowly degrade over several years.
     
  13. Jun 14, 2017 #12
    That's great to hear. I feel like I'm on the right track then. I too want to use 100% of the outside air. I'm trying to make a very small mobile air cooler to cool just a few cubic feet of space.

    Originally, I was going to use Dura-Cool pads until I read negative reviews, and then I thought I'd go with Aspen pads, but now I'm thinking about trying MasterCool rigid media which costs more.
     
  14. Jul 5, 2017 #13
    Further cooling of the air you previously cooled with evaporative cooling is going to result in very high humidity. The temperature will be lower than without the additional cooling, but it probably won't feel much cooler unless it is being mixed with fairly dry air in the house.
    What would make more sense would be to skip the difficult to sustain ice in water through coils part and use a heat exchanger to leverage the dry air advantage you have there.
    Cool outside air evaporatively and have this precool your inside air through the heat exchanger.
    The outside air is either then exhausted or precools the incoming outside air in a regenerative cycle heat exchanger and is then exhausted.
    The previous can be repeated in more stages if desired for colder air, at the cost of heat exchangers and fans.
    The inside air, once precooled through the heat exchanger can be evaporatively cooled through a wet pad.
     
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