Crushed Tubes In HX

[Larry Cobb]

OK , own up.

Whose HX picture was this posted on Feb.11 ??

It is a really unusual pattern for tube spacing.

It needs more tubes anyway.

Don't tell me it is a Vortex.

Larry

Edit: Saw the post on it from freeze damage.

 

[Mikey P]

yep, that's my Vortex.


It's been 55º all week long here. :shock: :shock:

 

[renegade_cowboy]

Larry is that the engine exhaust left of the 2045. That looks like a good buy for 10 grand.

 

[Duane Oxley]

Damn...

There's a huge difference there in wall thicknesses between the shell and the tubes. Somebody obviously opted for overkill on the shell to prevent injury, and underkill on the tubes for thermal efficiency.

It's not necessary, though. Thicker walls do transfer more slowly, but it works in both directions... heating up and cooling down. So, the time is basically taken off of the front end and added to the back...

Besides, welding to very dissimilar wall thicknesses can be a serious PITA.

Not to mention, as Larry said, weird pattern and too few tubes in the first place.

 

[Shane T]

I don't have any idea what machine that exchanger is off of but why do you guys say it needs more tubes? You don't have a clue what the dimensions of the shell or tubes are or even what engine is used.

 

[Duane Oxley]

I don't have any idea what machine that exchanger is off of but why do you guys say it needs more tubes? You don't have a clue what the dimensions of the shell or tubes are or even what engine is used.

You need as much surface area as possible to lose heat to the surrounding fluid..

That's why.

The only caveat to that is keeping it practical to weld in between the tubes on the end plates.

 

[Shawn Forsythe]

What we are talking about here is "Tube Pitch."
Tube pitch is defined as the shortest distance between two adjacent tubes.
For a triangular pattern, TEMA (Tubular Exchanger Manufacturers Association) specifies a tube pitch of 1.25 times the tube O.D. Thus, a 25 mm tube pitch is usually employed for 20 mm O.D. tubes.
Square patterns may be used to facilitate certain physical cleaning methods, but are not used if thermal efficiency is a priority.
Designers prefer to employ the minimum recommended tube pitch, because it leads to the smallest shell diameter for a given number of tubes. However, in exceptional circumstances, the tube pitch may be increased to a higher value, for example, to reduce shellside pressure drop, which is not an issue for this particular exchanger, because the tubeside pressure drop is the higher priority for engine exhaust systems that use the tubeside for the exhaust flow.

The design shown in Larry's picture seems to exhibit a haphazard, or arbitrary tube pitch and no pattern at all.