8 replies to this topic

[Monica_Staff]

Hi,

Does any body have any idea on how to calculate the pressure drop from a pipe that's 16" in diameter to a branched off pipe 1" in diameter, and finally to another branch of 3/4" diameter?. I cannot use Bernoulli's because my fluid is compressible. The original pressure is approximately 29 psia. Thanks for the help

[Andree]

I think that using Bernouli is still possible, but you need to recalculate properties (i.e. density) of your fluid (gas) at new pressure - iterative solution will be in this case:
1. assume new density,
2. calculate pressure,
3. calculate density of your liquid at new pressure and compare with assumed value,
4. assume new value until convegence is achieved...

The question is: how to calculate density at given pressure? There are many thermodynamic relations, the simplest (however not recommended) is ideal gas law, other include compressibiliti factor (z).

[JEBradley]

Completely agree with Andree - I just thought you might find this attachment helpful.

[Monica_Staff]

Thank you for the answers

[gvdlans]

Completely agree with Andree - I just thought you might find this attachment helpful.

The attachment seems to be missing...

[Art Montemayor]

Guido:

Good eye! I had to remove the attachment when I recognized it as a .pdf copy of a section from "Flow of Fluids through Valves, Fittings, and Pipe", Technical Paper No. 410, from Crane where the following is found on the Title page:

"All rights reserved. This publication is fully protected by copyright and nothing that appears in it may be reprinted, either wholly or in part, without special permission."

Unless JE or someone else comes up with Crane's special permission, I'm afraid I can't allow Tech Paper No. 410 to be distibuted through this Forum.

Sorry. But thank you for following through with your comment. This allows me to fully explain the deletion in its full context.

[Zauberberg]

I found this Excel spreadsheet long time ago, maybe it originates even from this forum and I remember it was for free. I cross-checked its outputs versus PIPESIM and HYSYS/PipeSYS results, and I found them to be very reliable.

If administrators of Che Forums agree, I will upload it so other members can use it. The authors are from River City Engineering company and I'm using this opportunity to make a some kind of advertisement.

http://www.rivercityeng.com/
http://www.rivercity...-Calc2Phase.pdf

Excel spreadsheet:

http://www.rivercity...P2000-v1.07.xls

Best regards,

[joerd]

That said, if you don't have Crane, you can still take a look at Art's own excellent workbook in
http://www.cheresour...?showtopic=4936
and follow the links he references in there. Most notably:
http://www.cheresour.../eqlength.shtml
and
http://www.engineeri...ssure_drop.html

[gvdlans]

Guido:
Unless JE or someone else comes up with Crane's special permission, I'm afraid I can't allow Tech Paper No. 410 to be distibuted through this Forum.

Sorry. But thank you for following through with your comment. This allows me to fully explain the deletion in its full context.

No problem. I fully understand the reasons...

Of course I have my own (legal) copy of Crane's Paper No. 410 at hand...

For those who don't have it yet, it costs $36 (so that's about 24 Euro's now ) + shipping/handling and can be bought via http://shop.flowoffl...FTechnicalPaper