1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Vacuum Chamber Question

  1. Jan 23, 2016 #1
    I'm building a vacuum kiln to dry wood and have some questions that may be rhetoric, since I am fairly certain I know the answers. I don't see a need to describe the project in great detail so I'll stick with the basics.

    The biggest challenge is applying heat to the wood. I believe I will have to use heat matts between each layer of wood because in a near perfect vacuum of 29.9 Hg a light bulb and fan will not work will it? I only ask because within the wood community some people have built a vacuum kiln and suggest that this works. But with no atmospheric pressure to speak of, how can heat from a bulb be conveyed within the chamber?

    The bulb will burn of course, and the heat has to go somewhere I suppose, so does it convect to be equally distributed within the chamber? And if it does, is the minute amount of air left in the chamber (I am at 600' MSL) enough to be a carrier of heat when a fan is running?
  2. jcsd
  3. Jan 23, 2016 #2


    User Avatar
    Gold Member

    The heat from the bulb will be conveyed by heat radiation. So the wood must be exposed.

    When the water in the wood evaporates ( boils at low pressure ) the wood will be cooled, so a powerful bulb is needed to keep up temperature.

    Also the chamber will be filled by steam, so you must have a powerful vacuum pump to maintain a low pressure.

    Mayby you should read how a "freeze dryer" works. ( Not sure about the name in english ).
  4. Jan 23, 2016 #3
    Thank you for your . . . . . rhetorical answer? (Not sure if if we are speaking english)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook