3 replies to this topic

[Kartik Totlani]

Hi

Can someone suggest a method/Correlations for determination of LMTD correction factors(F) in helical coil heat exchangers?? Can I use the one used in shell and tube heat exchangers?

 

thanks 

[mvp]

For preliminary design, use the same LMTD; then apply a correction for the Heat transfer coefficient for the coil side.

HTC multiplier = 1 + [3.5(Tube ID / Helical Dia)]

Good luck

[Steve Hall]

Aren't helical coil exchangers single pass by design? If so the correction factor is 1.0.

[breizh]

Back to my notes , I found that for gas inside a coil  , the heat transfer coefficient is calculated considering the equivalent length of  a straight pipe and the result is multiplied by (1+3.5* Di/Dhe ) . This could apply for liquid too.

 

Di : pipe inside diameter and

Dhe :helical diameter

 

additional input 

 

 

Jeschke (1925) provided an empirical correlation that allows for the increased heat transfer inside the coil

(2)

Where α_{i coil} and α_{i (straight pipe)} are the heat transfer coefficients on the inside of the coil and the equivalent straight pipe, respectively, and d_i and d_c are the internal diameter of the pipe and the diameter of the coil, respectively. 

 

 

 

Breizh

Edited by breizh, 07 May 2013 - 10:27 PM.