Flow of gas in a t-junction with one junction sealed.

  1. Hi I'm running an experiment in the lab right now where the kit has a flow of gas (such as oxygen and nitrogen) from the side. The trouble is that I am trying to expose the gas to a powder which will throw itself everywhere. I am currently thinking of using a T-junction pipe (as in the image below) and sealing one end so that I could put the sample in the bottom branch allowing the gas to flow over the sample but not cause turbulence such that the powder would be blown out of the junction.


    I'm not sure if the arrangement I have is the best solution. It may even be best to have the T junction sideways.

    The question is in terms of fluid dynamics do you think the gas exposure will be sufficient enough and would there be too much turbulence causing the powder to blow away? (I can't check by experimenting as if it fails it will damage the gas flow kit).

    Please suggest other arrangements such as different positions and longer branch etc...

    Thanks in advance. :)
  2. jcsd
  3. rollingstein

    rollingstein 636
    Gold Member

    How fine is the powder? I'd use a pair of very fine glass frit / disk and pack the powder between them. Gas can flow through pores, powder cannot.
  4. boneh3ad

    boneh3ad 1,953
    Science Advisor
    Gold Member

    I'm still not clear what your goal here is. How fine is the powder? What is its purpose? Do you have a diagram of yor proposed setup?
  5. Hi thank you for the replies and the powder is as fine and light as it gets since it is carbon nanotube (so almost atomically fine). Although they do tend to stick together forming various sizes of agglomerates approx <1mm in size. So i'll give the glass a go. Sorry one thing that I forgot to mention is the temperature it goes up to 1600 degrees celsius. Do you think pyrex glass survives this?

    The powder is the sample so the purpose of the powder is to be exposed to the gas.

    Below is a diagram of the potential set up:


    Sorry I'm not sure about the flow rate of the gas but if you could imagine blowing gently out of a straw that is the rough estimate.

    Thanks for your help again. :)
  6. rollingstein

    rollingstein 636
    Gold Member

    Regular glass / Borosilicate will not work at 1600.

    Silica glass just might. I think it softens somewhere around that temperature.
  7. rollingstein

    rollingstein 636
    Gold Member

    Another option might be to pack the powder sandwiched between beads of metal / ceramic etc. in a narrow bore pipe. The gas diffuses, the powder cannot.

    Some loss you can tolerate.
  8. I think the metal beads is the most effective candidate here. Thank you all very much for your help I will go ahead and try it out. :)
  9. rollingstein

    rollingstein 636
    Gold Member

    Only if your powder can be packed in. If it is too fine, you'll lose all powder. :)
  10. rollingstein

    rollingstein 636
    Gold Member

  11. Quarth wool will quickly degrade at 1600.
    I would suggest to use CNT-aerogel.
    Should nanotubes act as a catalist for some reaction? Can't imagine, what it can be.
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