Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Forced/Thermal Convection

Status
Not open for further replies.
SalvoR

SalvoR

Mechanical
Joined
Jan 26, 2023
Messages
2
Location
US
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!
 
Sort by date Sort by votes
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
 
Upvote 0 Downvote
@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.
 
Upvote 0 Downvote
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.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

AaronH
  • Question Question
FEA analysis with thermal loads
Replies
3
Views
4K
Stick.
Stick.
mmmssi
  • Locked
  • Question Question
specification of thermal oil boiler
Replies
4
Views
4K
LittleInch
LittleInch
ElCidCampeador
  • Locked
  • Question Question
Thermal oil heater
Replies
0
Views
1K
ElCidCampeador
ElCidCampeador
Ohuti
  • Locked
  • Question Question
Thermal oil calculations
Replies
4
Views
875
LittleInch
LittleInch
L
  • Locked
  • Solved
Dear all: what type of evaporatir should be used for caustic soda concentration up to 50%? Forced circulation or falling film?
Replies
10
Views
5K
pierreick
pierreick

Part and Inventory Search

Sponsor

Back
Top