×
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

Forced/Thermal Convection

Forced/Thermal Convection

Forced/Thermal Convection

(OP)
Hello everyone,
I am trying to figure out a heat transfer problem.
I am dealing with a 250-micron fiber optic strand that needs to heat to 300 degrees before entering an extruder. The strand goes into a preheater at 72 degrees, gets multi-wrapped (10 wraps) around sheaves, and then exits the preheater into the extruder. The preheater uses two Leister 61S heaters for heat and they both get their air blown by Leister's own airpak blower. We can assume 13 meter per second air speed out of each heater.
The fiber optic strand itself is moving 400 meters per minute. The height of the heating zone is 25 inches (.635 meters). This translates to roughly 250 inches (6.5 meters) of fiber strand in the active heat zone. At 400 meters per minute, 6.5 meters of strand is exposed to heat for about 1 second.

If I set the preheater temp to 500 degrees, what would the product's temperature be exiting the preheater?
Can anyone help me figure this out?
TIA!

RE: Forced/Thermal Convection

I presume that you know the heat capacity and TC of hte fiber strand.
You could start by assuming that the outside surface reaches 500 instantly and then seeing what the average bulk temp is after 1 sec.
You could try estimating some forced convection coefficients, but more important may be if you can keep the sheaves heated above 300.
I used to heat treat metal wire, 1950F for 2-5sec. It really just took testing to see if it worked because the numbers are so rough.

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

RE: Forced/Thermal Convection

(OP)
@Edstainless
Thanks for the reply. I'm still waiting for material property of the product. My guess is that the fiber will be similar to plastic. Next week we'll be running some tests using payoffs and takeups to stimulate the assembly line. At first I thought it would be a simple calculation but man, it's been over 20 years since using heat transfer and/or thermodynamics.

RE: Forced/Thermal Convection

Take a look at the differential equations on page 5-9 in the chapter on heat transfer in the 7th edn of Perry Chem Engg Handbook - suspect your case solution is an extension of one of these expressions. Note the heat transfer at the surface of the strand is the sum of convective and radiative components.

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


Resources

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