Heat transfer - Helical coil heat exchangers

[elogesh]

Hi,

This is regarding the heat transfer through helical coil heat exchangers.

Pl. refer the pdf in the indicated web-site,for your reference.

http://www.graham-mfg.com/downloads/14.pdf

Ours is closely similar...

Also refer following web-site

http://images.google.co.in/imgres?i...+coil+heat+exchanger+&svnum=10&hl=en&lr=&sa=G

The basic intention of heat exchanger in our application is replenish the waste gas heat from flue gas to heat the oil passing through the helical coils. The flue gas is in the shell.

The initial pressure and temperature of the oil and flue gas is known.We need to determine the outlet temperature,pressure of oil and flue gas.

We are planning to use the NTU method for the determination of outlet temoperatures.For determination of overall heat transfer co-efficient, I am not sure how to determine the heat transfer co-efficient (Nusselt's number) with helical coil. We are not quite sure, with empirical correlation to be used with helical coils.Whether empiricial correlations corresponding to flow across bank of tubes will be reasonable for Nusselt's number calculations?

I look forward for your comments/suggestions to proceed further.

Currently, we are proceeding with the pressure drop calculations on shell and tube side without accounting the temperature effects on pressure drop.

Reards,
Elogesh

 

[elogesh]

Hi,

Just now, I searched the prior threads and found some useful information provided by 25362 and montemayor.I am going through it.
I should have gone through the threads, before posting the previous thread.

I will go through previous threads and once again will come back and continue the thread.Sorry for the inconvenience.

Regards,
Elogesh

 

[insult2injury]

For helical coils, the nusselt number will be higher than that of straight tubes. There have been a few journal publications with empirical data. Those are probably about 20-30 years old. The correlations only span a limited range of sizes and are probably only accurate to about 10-15%.

I2I