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

Heat exchanger contractual point meaning

Heat exchanger contractual point meaning

Heat exchanger contractual point meaning

Hello everyone,

I am new on this forum, so I hope this topic does not already exist.

1) First, I would have confirmation that the sizing point of a heat exchanger is the operating point (let's say the triplet : Power to be evacuated P, T_Cold_Inlet and T_Hot_Outlet) that maximises the required heat transfer coefficient (KS_required in W/K).

2) Then, I would have confirmation (that correctly specified :)) contractual point of a heat exchanger must be the sizing point.

3) This is my main issue. I feel that the common practice is to specify to the supplier only one point (= the contractual point). Does this practice ensure that if we deviate from this contractual point (P_CP, T_Cold_Inlet_CP, T_Hot_Outlet_CP), we will still have KS_fouled_supplier(P_new, T_Cold_Inlet_new, T_Hot_Outlet_new)> KS_required(P_new, T_Cold_Inlet_new, T_Hot_Outlet_new) ? Even if KS_required(P_new, T_Cold_Inlet_new, T_Hot_Outlet_new) < KS_required(P_CP, T_Cold_Inlet_CP, T_Hot_Outlet_CP), maybe KS_fouled_supplier(P_new, T_Cold_Inlet_new, T_Hot_Outlet_new) will stall, I do not know the behaviour of the supplier function KS_fouled_supplier(P, T_Cold_Inlet, T_Hot_Outlet) which depends on the supplier heat exchanger design. Indeed, can you confirm that one point specification is sufficient in order to ensure correct sizing anywhere else (same question as for centrifugal pump specification, even if even more complex I guess).

4) Does the supplier ensure that its KS_fouled_supplier(P, T_Cold_Inlet, T_Hot_Outlet) > (KS_required(P_CP, T_Cold_Inlet_CP, T_Hot_Outlet_CP) - [X %]) ? Is there such a common criterion used by all heat exchangers manufacturers ?

Thank you for your help.

RE: Heat exchanger contractual point meaning

Selling heat exchanger must be like selling rubber band by the meter.

There are many parameters that can vary and all will impact performance.

I think you can rest assured that the vendor has learned all the loop hole the hard way and will not deviate when you hit one of the soft spots.

With reagrds to your fouling margin, if you specify this then the vendor will oversize to ensure that you still have the required performance at the fouled conditions as you say yourself.Fouling factor is normally specified as a resistance in e.g. ft2*ºF*hr/BTU or m³*K/W or whatever unit suits the vendor.

Best regards, Morten

--- Best regards, Morten Andersen

RE: Heat exchanger contractual point meaning

People do use fairly standard fouling factors, unless they have very accurate ones from experience.
The reason is that you don't really know, and in many services operators are not measuring enough parameters in real time to calculate the actual fouling factor. I have only ever seen this done in power plant condensers.
One risk is that oversizing the HX may by fouling margin but it will hurt effectiveness and maybe pressure drops.
Rather than asking for more test points, having some insight into the modeling may be more helpful.
If there is one parameter that might vary more than the others let the designers know, They can facto this in.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

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


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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