7 replies to this topic

[cincao]

Hi everyone,

 

Anyone knows the meaning of "pct tubes removed (both)" result in HTRI?
if I search in help, the description shows 

 

Percent of tubes removed under nozzles
For NTIW baffles, tubes removed in windows are included. (xxxx) prints as follows, indicating where tube removal takes place:

• NONE: no tubes removed
• HALF: tubes removed from only one side of the bundle
• BOTH: tubes removed from both sides of the bundle

 

I don't really understand where is the location under the nozzle. In my understanding, if the shell nozzle inlet location is above the shell, the tube will be removed from the top first.

But how about if the location is in the opposite direction? And where is the position of the removal begin? Is it from the middle and continue to the side or from the left first or the other location? 

 

Another question, how to find the input for this result (attached with red highlight) since I run my simulation, final result for "Pct tubes removed" always blank and shows "(half)" instead of "(both)".

 

 

 

Thank you

 

Regards,

Shane

Attached Thumbnails

• 

Edited by cincao, 29 October 2022 - 10:09 AM.

[Pilesar]

Shane, I use XIST 9 and do not recognize the screenshot. Are you using the latest version of the software?  I have found HTRI tech support to be helpful explaining program output. Are you specifying an NTIW exchanger? You may also have specified under the nozzle input for shell exit construction 'remove tubes if TEMA requires.' You can view the tube layout drawing to see the final result.

[cincao]

Hi Pilesar,

 

I use 8.0.1 and 7 version, there is nothing different with the result format with both version.

You can find tube information section at the bottom of first page in "final results"

 

Nope, I specified single segmental baffle type

That was the description from help, I copied directly here 

Edited by cincao, 29 October 2022 - 08:32 PM.

[Pilesar]

OK, I followed your pointing. Tube removal is affected by the shell entrance and shell exit construction settings on the Nozzle input tab. The 'half' means tubes were removed from only one side of the bundle to satisfy the entrance and the exit nozzle criteria. 'Both' means tubes were removed from both sides of the bundle. The note applies to the automatic tube layout to indicate that the software modified from 'full' layout. I rarely use the final results tab and spend much more time cycling between the output summary, the vibration tab, and the 2D layout drawing.

  The location under the nozzle is the space you would see inside the shell if you were to look through the nozzle from the outside. Orientation is not implied and may be up for bottom nozzles, down for top nozzles, or sideways for vertical shells. It is straight under the nozzle as if you were to put a stick into the nozzle. Removing tubes that crowd the nozzle reduces velocity and lowers fluid momentum. This affects impingement, vibration, and pressure drop.

[cincao]

Thanks for the explanation Pilesar

 

By the way, I figure out to obtain the same pct tube removed result by adding the crosspasses number and baffle spacing

I don't know the HTRI calculation, why by adding this crosspasses number can generate the same result but when I input the baffle spacing which give the same crosspasses number, the tube removed result is none.

[Pilesar]

Thanks for the follow-up. I kept trying to get the percentage as percent of tubes and could not duplicate HTRI results. So maybe this is reported as percent of total bundle area. The reported number is still not something I would know how to use in exchanger design.

[Pilesar]

There is software bug in HTRI XIST 9 which results in some malfunctions when the number of crosspasses is left blank in the input. The bug may have existed in earlier versions also. I do not know what all portions of the program are affected, but it seems like you may have stumbled upon related software malfunction. 

[cincao]

I see. So you obtain the same issue as well

In my opinion, this information is not critical for design because until the newest version, the problem still exist.

I hope someone can reach to HTRi technical support to fix this

 

Anyway, thanks for your response Pilesar