×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Moisture in LN2

Moisture in LN2

Moisture in LN2

(OP)

Thanks for you comments.

Although the moisture is in very low concentrations I am still interested in what happens to it as the equipment I am designing must not suffer from icing over an extended period (2 - 5 years.  To prevent icing I intend to place the dewar in a very dry environment (-60 to -70°C dewpoint)

At this level the water in the air will be approx 2vpm.

I have done some tests at much higher dewpoints (-30°C) observing the icing rate and have extrapolated to estimate the required DP for extended use.

Another tricky problem is moisure vapour travelling up the nitogren vent connected to  the sealed dewar.

I intend to prevent this by having a long small bore tube to maximise the gas velocity. I am trying to calculate the vapour flow up the pipe under static conditions using Fick's law and then intend to estimate the mass flow rate of nitrogen required to maintain equilibrium.

Does anyone know the diffusion rate of water vapour in dry nitrogen? Or indeed a better way of approximating the required dimensions of the vent pipe?

Are there any surface coatings that inhibit ice build up (or at least adhesion) and what is "acunolate residue"?

All help gratefully received

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close