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!

*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.

Jobs

Ashrae fundamentals calculation - heat transfer off insulated pipe.

Ashrae fundamentals calculation - heat transfer off insulated pipe.

Ashrae fundamentals calculation - heat transfer off insulated pipe.

(OP)
Hi,
I've been setting up a calculation following the heat transfer calculations outlined on pages 4.3 & 4.4 of the ashrae fundamentals handbook (2017). I've been using their example to check my spreadsheet before adapting for my actual calculation.
The problem is I can't seem to get all the numbers to pan out. I was wondering if someone else could crosscheck for me to see if it is me or the document that is wrong.

I don't really want to post the actual text for copyright infringemnt reasons, but I am getting different answers for both R2 & R3.
The stated results are
R2 = 3.37*10^(-5) h.degF/Btu
R3 = 0.254 h.degF/Btu

The results I am getting are
R2 = 2.82*10^(-6) h.degF/Btu
R3 = 0.021 h.degF/Btu

In both cases I am out by a factor of 12 which is obviously a feet-to-inches conversion, but in the context of how the information is presented this does not make sense.

thanks in advance.

RE: Ashrae fundamentals calculation - heat transfer off insulated pipe.

I don't use ASHRAE so I would not be familiar with the formula. From what you revealed, the only thing that I can think of, is the thickness of the insulation; one equation has feet for the thickness and the other thickness is in inches.

RE: Ashrae fundamentals calculation - heat transfer off insulated pipe.

Are the conductivity values in BTU/hr.in.F or Btu/hr.ft.F? If the value is in inches, consider pipe length in inches.

RE: Ashrae fundamentals calculation - heat transfer off insulated pipe.

(OP)
Iguess that is it, thanks Quark!

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


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