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How does compression cool water in a household water cooler?

  1. Apr 28, 2017 #1
    How does compression cool water in a household water cooler? I was reading and it says, "
    The water inside the water cooler is fed into a reservoir, where it is cooled using a refrigerant. A refrigerant is a cooling medium that is circulated in pipes that are located close to the reservoir in the water cooler. The refrigerant changes from a liquid to a gas as it moves in the pipes towards the reservoir because of the pressure in the pipes created by a compressor inside the water cooler. The cooled gas in the water pipe is forced through a valve to make it even colder.

    When the refrigerant is in a gas form and is circulating in the pipes, it has the ability to absorb the heat away from the mineral water in the reservoir, leaving cool and refreshing water that is readily available. The heat in the refrigerant is then expelled from the water cooler." Could someone not only explain the science behind this, but also the general engineering behind it? Thank you!
     
  2. jcsd
  3. Apr 28, 2017 #2

    russ_watters

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    Staff: Mentor

    As your source says, compression of the refrigerant doesn't cool the water, evaporation of the refrigerant does. Any liquid, including water, cools itself when it evaporates (that's why sweat cools you). Some chemicals are better at it than others, but if you expand and reduce the pressure with a throttling valve, a liquid can boil and get colder. Then you run it through a heat exchanger to complete the boiling, cooling the water. The compressor turns the warm gas back into a liquid, which also heats it, allowing you to reject that heat into the atmosphere, completing the cycle. Basically all refrigerators use the same principle:

    https://en.m.wikipedia.org/wiki/Vapor-compression_refrigeration
     
  4. Apr 30, 2017 #3
    Depending on the refrigerant, you may find the 'plumbing' of your heat-pump is more complex than the usual drawings. There's often an un-labelled 'sausage' with two or three connections that serves no obvious purpose. If you dig really, really deep with your preferred search engine, you should find this whatsit is a combined mist-catcher and dessicant pack. Without it, condensate spray can get to parts of system where it should only be gas, and traces of moisture in the refrigerant may ice-up and choke the 'expander' valve. A damp 're-gas' after a repair and/or excessive jolting / vibration can overwhelm the dessicant or collapse the whatsit's brittle internal matrix, causing baffling fault symptoms. We had a fridge-freezer's pump replaced twice under warranty before the service guy figured the real cause of the unit's cooling 'stalling out' around freezing point instead of '~20 below' (C')...
     
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