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

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Discussion Overview

The discussion revolves around the design of a T-junction pipe for exposing fine powder (carbon nanotubes) to a gas flow while minimizing turbulence that could disperse the powder. Participants explore various configurations and materials suitable for high-temperature applications, as well as the implications of powder characteristics on the setup's effectiveness.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests using a T-junction pipe with one end sealed to expose the powder to gas without causing turbulence.
  • Another participant inquires about the fineness of the powder and proposes using fine glass frit to contain the powder while allowing gas flow.
  • A participant expresses uncertainty about the purpose of the powder and requests clarification on the proposed setup.
  • The original poster clarifies that the powder is carbon nanotubes, which can agglomerate, and asks about the suitability of Pyrex glass at high temperatures.
  • One participant warns that regular glass or borosilicate glass will not withstand temperatures of 1600 degrees Celsius, while silica glass may be a possibility.
  • Another participant proposes packing the powder between beads of metal or ceramic in a narrow bore pipe to prevent loss while allowing gas diffusion.
  • A participant expresses confidence in the metal beads approach as a viable solution.
  • Concerns are raised about the potential loss of powder if it is too fine to be effectively packed.
  • One participant mentions that quartz wool would degrade at high temperatures and suggests CNT-aerogel as an alternative, questioning the catalytic properties of nanotubes.

Areas of Agreement / Disagreement

Participants present multiple competing views regarding the best approach to contain the powder while allowing gas flow, and there is no consensus on the optimal material or configuration for the setup.

Contextual Notes

Participants discuss the limitations of various materials at high temperatures and the challenges posed by the fine nature of the powder, including issues related to packing and potential loss of material.

Who May Find This Useful

This discussion may be of interest to researchers and practitioners working with gas flow systems, high-temperature applications, and the handling of fine powders in experimental setups.

sfa2560
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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. :)
 
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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.
 
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?
 
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. :)
 
Last edited by a moderator:
Regular glass / Borosilicate will not work at 1600.

Silica glass just might. I think it softens somewhere around that temperature.
 
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.
 
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. :)
 
sfa2560 said:
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. :)

Only if your powder can be packed in. If it is too fine, you'll lose all powder. :)
 
1-s2.0-S0021951709004217-gr1.jpg
 
  • #10
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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