×
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

Formula for calculating heat loss from single pipe - cold spot

Formula for calculating heat loss from single pipe - cold spot

Formula for calculating heat loss from single pipe - cold spot

(OP)
Hi,

I am trying to calculate heat loss from a pipeline in a forced convection (sea current) scenario.  I have been going through several heat transfer textbooks, but all I can find are formulas for pipe bundles (for heat exchangers).

A bit of background info: In this particular case, we have several existing interfield multiphase pipelines that have seen internal corrosion at locations where the pipelines are exposed to seawater, e.g. at external sacrificial anodes, subsea flanges, etc, as this is where water condenses out, especially at the top of the line, where conventional corrosion inhibitors can not reach (as these remain dissolved in the liquids at the bottom of the pipe - stratified flow). A suggestion has been made to cover these sections with sandbags or some other type of cover, thus effectively reducing the external seawater velocity to zero (or close to).  The pipes will still be exposed to seawater, but hopefully the new convection will now be natural rather than forced.

Considering the amount interfield pipelines we have (in excess of 120), and the cost of covering these cold spots, we would like to make a comparison of the heat transfer coefficients for the two cases.  Calculating the natural convection is easy enough, but I have not been able to find a suitable equation for forced convection for single large diameter (10-16 inches) pipes.

Would be very grateful for any leads you guys can give me.

Cheers,

Trond

RE: Formula for calculating heat loss from single pipe - cold spot

A good book on heat transmission should have that correlation.
My McAdams (OK, a little oldish...blush) gives various relationships for the flow of liquids normal to single cylinders and recommends the following one:
Nu/Pr0.3=0.35+0.56 Re0.52

prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads

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