I think this correction is wrong or it is a printed mistake

[Carol3377]

Dear all,
I think the ESDU Correlation to get the j number in the book HEAT EXCHANGER DESIGN HANDBOOK written by T.KUPPAN (in both editions) is wrong, or maybe it is a printed mistake.
I think it should be Re^(-0.3) instead of Re^(+0.3) in this equation.
Since I cannot find more support information about this, could you please give me more information about this correlation.

 

[IRstuff]

The correlation looks consistent with other similar correlations. You're asking for the Reynolds number to be in the denominator, which would force the Nusselt number to be very small, since the Reynolds number is usually extremely large. Try it with Re=10^4

As for the correlation itself, you'd have to look at the specific references the author used. There are probably as many correlations as there are authors.

TTFN
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faq731-376 forum1529

 

[Carol3377]

Thank you for your kind response.
Actually, I've checked several other correlations, and the Reynolds number is in the denominator, and the Nusselt number may not be very small, because j=Nu/(Re*Pr^1/3).
The thing is, I now cannot see the details of the specific reference the author used unless I buy it.
But after comparing with other similar correlations, I am now quite sure it is a printed mistake. It should be Re^(-0.3).

Thank you.

 

[IRstuff]

I left off a link:

http://www.pathways.cu.edu.eg/ec/text-pdf/part b-9.pdf

which shows that all the correlations have Re in the numerator. The only time Re is in the numerator is when it's within a natural log, but in all of those cases, there's an Re in the numerator.

That's consistent with

http://www.seas.upenn.edu/~meam333/correlation/CorrelationsList.pdf

>> the second link shows Re in the denominator for calculations for packed beds, so maybe in that case, that's correct

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

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faq731-376 forum1529

 

[ione]

From the its definition:

j = Nu/(Re*Pr^(1/3))

Now Nu is a function of Re where Re has always an exponent <1. So Colburn j-factor should always decrease with Reynolds.

Carol3377, I’m quite prone to think you’re correct. Have you tried to contact the editor of the book?

 

[Latexman]

See if there is errata on the publisher's or author's website.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[Carol3377]

Thank you all. By calculating, I'm pretty sure now its a mistake in the book. I will tell the editor of the book according to your advices.