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I Room coolers?

  1. Jul 3, 2018 #1
    It has been an unusually hot summer where I live.
    I am not surprised to be getting ads for 'room coolers' due to this.
    However are not such devices contrary to well known physics?
    In regions where hot summers are usual. air conditioners are used, they pump the excess heat outside.
    How though can a device standing in any room chill the air without having a heat dump?
     
  2. jcsd
  3. Jul 3, 2018 #2
    It is not possible.
    I just looked as several devices that fall under the shopping category of "Room coolers".
    Some are dehumidifiers. Some are allergen filters.
    In some cases, it's hard to tell, such as this one:
    https://www.target.com/p/as-seen-on...VRQOGCh1z9QsSEAQYAyABEgJlzPD_BwE&gclsrc=aw.ds
     
  4. Jul 3, 2018 #3

    kuruman

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    Here is a description of the principle behind a device advertised as an "evaporative cooler". Presumably it sucks the heat of vaporization from the air.

    As the air flows through the wick, some of the water evaporates into the air, consuming the heat that was in the air. An air stream is then blown out the front of the unit and is considerably cooler than the current room temperature.

    I would read reviews before buying anything of this sort.
     
  5. Jul 3, 2018 #4

    phinds

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    If you want to cool of an entire room, you are correct. If you want to cool off YOU, then evaporation coolers work just fine. It's like blowing a fan over your body when you are sweating. You heat up the room overall, but you sure cool yourself off.
     
  6. Jul 3, 2018 #5

    phinds

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    I have one of those "Arctic Air" things and it works. It doesn't put out very much in the way of cool air but it IS noticeably cool and when I add a small desk fan and blow both directly on me from nearby, it's definitely cooler than just the fan. I don't care if it warms up the room slightly, 'cause it cools me off just fine.
     
  7. Jul 3, 2018 #6
    Ah, I get it now.
    A regular fan would be nearly as good.
    Better still if the fan is placed too blow over scrapings from the fridge ice box.
    It turns into hyperfrost once in a month anyway.
     
  8. Jul 4, 2018 #7

    sophiecentaur

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    Particularly when the fridge is in a different room!

    Swamp Coolers are fine in countries with low humidity. I had one in the Lab in the UK, one hot summer. The results were quite disgusting; the humidity went even higher and the device ended up smelling terrible.
     
  9. Jul 4, 2018 #8

    bob012345

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    You could have a different way of storing the heat instead of the usual heat dump to the outside. Just have a phase change material such as ice. Of course you have to make the ice somewhere else. Alternatively, you could melt wax which would remove energy from the ambient air in the room if you could create wax of the desired temperatures. Of course you would have to freeze the wax somewhere else later too. Technically, these are heat dumps though.
     
  10. Jul 4, 2018 #9

    OmCheeto

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    hmmm... I have an unused* fridge on my back porch.
    This brings back some bad memories. <snip! long story! :angel:>

    Anyways, I'm not sure why people don't just install a window A/C unit. From my googlings, the little ones run now for about $125.
    And although they claim to be only appropriate enough for 150 ft2, mine keeps my 900 ft2 house quite comfortable.
    Of course, my local conditions might have something to do with that.

    hmmm...... (google google google)

    $75 seems even a better price.

    ac.unit.75.us.dollars.png



    -----------
    *"unused" in this case means not used for its intended purpose. It mainly is just for storing odd bits and pieces that I think I may have a use for in the near future. It's unplugged, of course.
     
  11. Jul 4, 2018 #10

    sophiecentaur

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    It's the running cost that's the killer with AC. Also, I wonder what the life of such a cheap compressor unit would be. Good refrigeration units go on foe ever and ever.
    Perhaps the personal cooler (as with astronauts) could be developed. Come on @OmCheeto see what you can do and let us have the photos. :smile:
     
  12. Jul 5, 2018 #11

    cjl

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    Evaporative (swamp) coolers can absolutely cool a room below ambient, so long as the humidity is low. Water evaporation will cool the surroundings, and as long as there's sufficient air exchange with the rest of the environment to keep the room from getting saturated with humidity, a swamp cooler will continue to keep a room cool.
     
  13. Jul 5, 2018 #12

    phinds

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    Yes, I misspoke about it heating up the room.
     
  14. Jul 5, 2018 #13

    CWatters

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    Here in the UK you can get portable AC units that have a 4" diameter hose to vent the hot air outside. They don't always show the hose in adverts.
     
  15. Jul 5, 2018 #14

    sophiecentaur

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    This totally true if you live in a hot, dry climate. Hopeless in the UK. When the room gets to a state of what should be 'cool' it is merely cold and clammy. Awful and worse than the familiar 'to damn warm'.
     
  16. Jul 12, 2018 #15

    rude man

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    Swamp (evaporative) coolers work only in regions of very low humidity, say below 10-15% RH.
    The basic principle is actually the same as that of air conditioning: evaporating a liquid absorbs heat. But the air conditioner works in a closed cycle whereas a swamp cooler requires evaporation to the outside (your room), which doesn't happen if it's at all humid.

    In most regions of the country these portable coolers are nothing but a scam. And if you do live in a dry region such as Phoenix or Las Vegas, a proper wall or roof cooler is the way to go. The troubles with these phony portable coolers is so endless a list that I cannot even begin to enumerate them. Just believe a 50-year desert resident.
     
  17. Jul 12, 2018 #16

    russ_watters

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    Please note, two separate types of devices are being discussed in this thread:
    -Evaporative coolers
    -Portable room air conditioners

    The term "room cooler" is not a term of art I'm familiar with, so I can't be sure, but google implies it is a portable room or spot air conditioner, not an evaporative cooler.

    The pictures in the ads may be misleading if they don't show the hose coming out the back.
     
  18. Jul 12, 2018 #17

    rude man

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    Of late the tv waves have been saturated with room swamp cooler ads so it is likely the OP is referring to these.
    They are a scam, even in dry areas. Water has to be replenished every few hours or so. Mineral buildup soon corrodes the frame and renders the pads useless, which therefore also have to be replaced frequently. Without proper drainage, mineral buildup happens in a matter of days, not weeks or months. You can estimate it by writing a 1st-order ODE as I have done. I use an RO system to feed my cooler clean water and still drain continuously.
     
  19. Jul 12, 2018 #18

    Mark44

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    I lived in the same state you're posting from back in the mid-50's. Virtually all of the houses had swamp coolers, and only a few had central air conditioning. In the four years my family lived there, we used the swamp cooler probably six months of the year. I don't recall that we replaced the excelsior pads or had any problems with mineral buildup, but I think we also had a water softener, so that might have reduced the mineral deposits. Of course water has to be replenished -- the unit works by evaparating the water in it.
     
  20. Jul 12, 2018 #19

    rude man

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    If you recall, your AZ swamp cooler had a water inlet port. Room units have no such proviso so you have to manually refill them every few hours.

    A water softener probably accounts for your allegedly trouble-free operation. That might also have obviated the need for a drain port. So a "portable cooler" should come with a warning that a water softener, an R/O system or the use of distilled water is required.

    In the '50's Phoenix et alia had a much cooler climate than now. So swamp coolers worked better then. (For the record, my wife's parents had a swamp cooler & she told everyone she married me to get into air conditioning! They however also succumbed finally and got an a/c unit.)
     
  21. Jul 12, 2018 #20

    Mark44

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    Yuma seemed pretty hot to me back then. It was regularly in the 110's and even up to 120 at times in the years I lived there ('54 through '58).

    In '57 my family drove back east to visit family in our '56 Ford convertible. In those days cars weren't usually equipped with AC, but we had a small swamp cooler in the car that sat on the transmission hump and was plugged into the cigarette lighter receptacle. I'm sure it helped as we drove across Ariz., N. Mex., and Texas.
     
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