×
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

the heat transfer coefficient of water

the heat transfer coefficient of water

the heat transfer coefficient of water

(OP)
can i know whether the inside heat transfer coefficient, hi and the outside heat transfer coeffcient of water flows inthe pipe, ho is how much ? Is it must lie between the range of 1000 to 2000 W/m2.oC?

RE: the heat transfer coefficient of water

Im not quite sure if i got the question but yes: You can calculate the heat transfer coefficient. For water as for any liquid or gas you need:

-Thermal conductivity of liquid, k (water 0.59 kW/m C)
-Heat capacity, Cp (water: 4190 J/kg C)
-Viscosity, visc (water 0.001 kg/m s)
-Density, den (water 1000 kg/m3)
- Pipe diameter, D (m)
- Flow, V (m3/s)

1) Calculate Reynolds no.
Re= V*D*den/visc
2) Calculate Prandtls no:
Pr=Cp*visc/k
Use the correlation by Nussel:
Nu=0.023*Re^.8*Pr^.33

and

Nu=h*D/k

where h er the inside/ouside heat trabsfer coefficient.

When calculating from the outside (assuming the problem conserns pipe in pipe HX) use hydraulic diameter for D and calculate liquid velocity based on free area between pipes.

This is 100% standard heat transfer theory and any text book on the subject should tell you this.

Best Regards

Morten

RE: the heat transfer coefficient of water

(OP)
yes, i did the calculation as u show to me. But the problem is the values of hi and ho are very high, hi=5024 W/m20C and ho = 3800 W/m20C.

My design is actually an agitated reactor with immersed cooling coils. Cooling water is flowing inside the coils while glucose solution is outside the coil. My task now is to determine the number of coils used. At first, I need to calculate the heat transfer area. Therefore I need to calculate the heat transfer coefficient inside and outside the coils.

From the Coulson & Richardson (1993, Volume 6), hi for an agitated vessel is

hi x k /D = 1.10 Re(0.62) Pr (0.33)

and ho = hi x ID/OD

and Ud= 1/Uc + Rd where Rd is the fouling factor which i used 0.0003 m2oC/W.

After calculation, the result is hi around 5024 W/m2oC
                                 ho around 3800 W/m2oC
                                 Ud aroung 2000 W/m2oC

Do u know the overall heat transfer coefficient for a system consists of glucose solution (hot fluid) and cooling water (Cold fluid) in a heat exchanger system?

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