Non newtonian pressure drop

[Lijantropo]

Good morning,

I have to pump a non-newtonian fluid (an emulsion). I know some lab properties of the fluids (enough to estimate the apparent viscosity) but I'm not sure of what set of equations I should use. Do you have any good reference where I can find simplified equations for make a good estimation of pressure drop in pipes for this kind of fluids?

(pd: I have read some papers where the autors suggest to use the same equations for newtonian and non-newtonian fluis, changing only the viscosity. What do you think?)

Regards,

lij.

 

[Latexman]

It depends. What is the rheology of the fluid? Most, but not all, emulsions are shear thinning.

Good luck,
Latexman

 

[Lijantropo]

Hi,
You're right Mr Latexman, it is shear-thinning.
lij

 

[Latexman]

Then as long as the shear rate created in the pipe is greater than the shear rate of the lab viscosity measurements, using the lab viscosity in a Newtonian method is conservative.

I gave an excellent reference a while back. Do a search here and in the Chemical Engineering forums and see if you find it. If not, let me know and I'll repeat it. It was a series of articles in Chemical Engineering Magazine.

Good luck,
Latexman

 

[BigInch]

Conservative for pressure drop, but ... unconservative when maximum flowrates are of interest.

"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[Latexman]

BI,

Agree. If one takes the easy way out, there is usually a catch!

Good luck,
Latexman

 

[BigInch]

Ya. Always at least 1 one fly in the ointment, 1 alligator in the swamp and 1 barracuda inside the jacket leg perimeter.

"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[Lijantropo]

Good morning,

I have been searching in Chemical Engineering Magazine. I found this articles:

http://www.che.com/articles/1985-1999/Vol95/chevol95_num18_437.html

http://www.che.com/download/facts/CHE_Facts_1208.pdf

http://www.che.com/articles/1985-1999/Vol95/chevol95_num18_430.html

Regards, Lij

 

[BigInch]

For the most part you just need to formulate some equation to relate viscosity to (normally via shear to) vs velocity.

It gets tricker if your viscosity varies with time at various velocities, or has other more devious complications.

"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[Latexman]

Lijantropo,

Look here:

thread378-243822

Good luck,
Latexman