Shellside Fluid Velocity - Heat Exchanger Design

[Ricardo11]

Hello everyone,

I'm currently designing a vertical shell-and-tube heat exchanger, and I understand that the typical target range for shellside velocity is between 0.6 and 1.0 m/s to ensure good heat transfer and mitigate fouling.
In my case, the shell-side fluid is water, and I've already tried adjusting both the baffle spacing and shell diameter to increase shellside fluid velocity. However, the maximum velocity I'm achieving on the shellside is only about 0.3 m/s.
Should this be a concern? Even though the fluid is water, could such a low velocity lead to fouling or excessive deposit formation over time?
I did some tests and managed to reach a shell-side velocity of 0.7 m/s, but it required a large number of baffles, which might not be practical from a fabrication or cost standpoint.

I also have another question regarding allowable pressure drop:
When no specific values are provided by the client, is there any rule of thumb I can follow?
For example, would it be reasonable to assume around 0.5 bar on the shellside and 1 bar on the tubeside?

Any guidance or experience would be greatly appreciated.

Thank you in advance!

 

[georgeverghese]

Min baffle spacing is D/5, where D = shell dia. I'd suggest also using up to 70% of the available shellside pressure drop in order to maximise shellside htc.

 

[pierreick]

Hi,
Consider these documents to support your work.
Good luck
Pierre

 

[shvet]

@Ricardo11
It looks like you have a long way to go. Pressure drop, fouling, velocities ranges/limitations - all these are a core of thermal and hydraulic design of the HEs. Hope you understand that a fouling margin/resistance specified is referenced to a velocity range and becomes irrelevant once a limit is exceeded. Note that you are able to split the HE to 2 shells in series and 2 tubes in parallel to adjust the shell side velocity.

I retrieved the relevant material from my archive to the file attached. Note that this is only a small tip of an iceberg when it comes to fouling issues.

Curious why asking at the anonim webforum instead of looking through few thermal handbooks?