Jar of water in a box, how would You prevent condensation?

  1. I'm not sure if this is the right section... But

    Assume you have a medium sized box (about as big as a large desktop computer) inside a room.

    And inside the box there is a jar of water that is significantly colder than the outside temperature.


    How would you prevent water condensation from occurring inside the box?


    Rules (the ones I can think of so far..):
    - You cannot lower the rooms temperature to match the water.
    - The solution should be semi-reasonable.

    I have a few Ideas but I'll like to see if anybody else can come up with them first. Thanks.
     
  2. jcsd
  3. mfb

    Staff: Mentor

    Water condensation from the air in the box, at the jar?
    • Insulate the jar
    • Use dry air inside the box to lower the dew point below the jar temperature
    • Heat the outside of the jar

    All three methods get used in real applications.
     
  4. The jar...

    I've got a better example though, assume you have a cardboard box, with a tube running through it horizontally. The tube is carrying sub-ambient water through it and you don't want water to condensate on the tube (or anywhere for that matter) so that the box will became wet. Even a little bit of moisture is failure, any ideas?


    Judging from what you said, would a mini de-humidifier inside the box work? What if the air on the outside of the box is still humid? The box isn't airtight. Would that have an effect?
     
    Last edited: Apr 14, 2014
  5. mfb

    Staff: Mentor

    The three options are still my answer, and which one is best will depend on the specific application.

    If the box is not air tight, it can have an effect.
     
  6. What do you mean exactly by insulate the jar / tube?

    Would plastic or something work?

    Edit: What do you think about the box having alot of airflow? Would that have any effect on the condensation?
     
  7. Baluncore

    Baluncore 2,605
    Science Advisor

    1. Cap the jar to prevent ongoing evaporation, then put a pack of silica gel in the box to dry the air.

    2. Coat all surfaces inside the box with a strongly hydrophobic substance such as a silicon polymer anti-fog windscreen treatment.

    This hypothetical question has too many arbitrary degrees of freedom.
     
  8. mfb

    Staff: Mentor

    Some thermal insulation layer around the tube. Polystyrene foam ("Styrofoam") or whatever you have available.

    If it is dry air, sure. Otherwise, it depends on the setup.
     
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