convective heat transfer coefficient equation

[vesselguy]

Hi all,

I have done some searches in this forum to find out what is the best equations to use to calculate the convective heat transfer coefficient. I think the best tip I've seen so far is a reference to ASTM C680. I do not have this standard. I'd try to find it in my local university libary later this week. But meanwhile, I would like to ask the experts here which correlations are known to be most accurate. BTW, the application I want to use it on is calculating ho due to ambient air flowing over a hot or insulated surface induced by a wind velocity. The other similar application would be to calculate the ho inside a vessel skirt.

 

[davefitz]

Try the following link- the europeans tend to use the Gnielinski correlation

<

http://www.nd.edu/~msen/Teaching/IntHT/Slides/08B - Chapter 8, Sec 8.4 - 8.8 Black.ppt>

 

[Twoballcane]

Hmm I think you can find the equations in any Heat Transfer text book. The hard part is the iteration portion to come to a heat transfer coefficient number. However, once you can do one, you can do others.

Tobalcane
"If you avoid failure, you also avoid success."

 

[IRstuff]

see chapter 6 in Lienhard's free HT textbook:

http://web.mit.edu/lienhard/

http://www/ahtt.html

TTFN

FAQ731-376

 

[vesselguy]

Thank you IRstuff and Davefitz.

Twoballcane, In the past, I have always use the correlations provided in the book by James Sucec. However, I have noticed that my calculated values varies greatly with numbers calcualted by others using different sources. That is why I am asking this question. I'm hoping there is an industry acknowledged equations to use. That's all.

Thanks again, all.

 

[IRstuff]

The fact that there are "different sources" already suggests that there is no accepted standard, since everything is empirical, and the ability to measure htc under controlled conditions is quite difficult.

TTFN

FAQ731-376

 

[vesselguy]

IRstuff,
I can only hope.