×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Pressure drop in a pipe

Pressure drop in a pipe

Pressure drop in a pipe

(OP)
hi,

I am trying to evaluate pressure drop in an oil pipe. My problem is that I know that there is also air involved (~ 0.1%). The question is, how does the air influence the pressure drop? (notice i am talking about 0.1% air)
I heard opinions both ways (pressure drop shall fall/rise) but no solid explanation.

please enlighten me...

thanx

guy

RE: Pressure drop in a pipe

(OP)
bouncing

RE: Pressure drop in a pipe

The solubility of air in hydrocarbons at 273 K as given by the Ostwald coefficient is 0.095. Meaning that 0.095 volumes of air are dissolved in one volume of hydrocarbon at atmospheric pressure (ie, 9.5%). The method used to measure gas solubilities is described in ASTM D2779-92(2002).

This would imply (although not ensure) that 0.1% v/v air at room conditions would stay dissolved in the oil and not appreciably affect the friction drop as long as pressure doesn't drop too much and the gas is released from solution.

Sometimes air is chemically absorbed by the oil (oxidation) further reducing its availability. The solubility doesn't change much until profound chemical changes warrant a new Ostwald number.

The -as published- effect of temperature, T (absolute) on the Ostwald coefficient Co (at 273 K), is as follows:

CT = 0.3 * e[0.639(700-T)/T] * (ln 3.333Co)

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!


Resources