8 replies to this topic

[Mudassir Khalil]

Hi all,

I would like to know the criteria of line sizing for viscous fluid with viscosity around 5000 cP.

 

Thank you,

Mudassar Khalil

 

[ankur2061]

Mudassar Khalil,

 

There is no special criteria for pressure drop of viscous liquids flowing in pipes if you are considering the liquid flow behavior to be Newtonian. If the flow is Non-Newtonian than the power-law equation applies considering whether the fluid is Dilatant (shear thickening), Pseudoplastic (shear thinning) or a Bingham plastic.

 

Non-newtonian flow behavior is found when dealing with slurries, gels, molten plastics, suspensions etc.

 

The generalized Darcy-Weisbach equation should be used for pressure drop or head loss in pipes when dealing with Newtonian fluids even for high viscosities.

 

One aspect that although needs to be considered is the equivalent length of pipe fittings and valves when dealing with viscous fluids. For viscous fluids the flow regime is laminar and the Reynolds number is very low. The 2-K method of calculating the equivalent length of fittings and valves in the laminar flow regime appears to be more realistic when dealing with viscous Newtonian fluids. A very enlightening discussion on the 2-K method for calculating equivalent length can be found at the following link:

 

http://www.cheresour...1882#entry31882

 

Hope this helps.

 

Regards,

Ankur.

[Mudassir Khalil]

thank you @ Mr. Ankur for your reply.

Actually I am dealing with Neat soap which is Pseudoplastic fluid. Is Q=AV relation is valid in case of Pseudoplastics?
Can you please reffer me any book/paper or standrard for hydraulics of this fluid?.

 

Regards,

Mudassir Khalil
 

[ankur2061]

Mudassar,

 

Refer the link below on a top rate article on flow behavior of Non-Newtonian fluid. This article is on "Chereources" itself and from a very respected "Cheresources" member Steve Hall.

 

http://www.cheresour...rsus-shear?pg=1

 

Regards,

Ankur.

[kkala]

A treatment on non Newtonian fluids can be found in Coulson and Richardson's Chemical Engineering, Volume three, Pergamon Press 1971 (there may be newer editions), Chapter 6 - Non-Newtonian technology (70 pages), including pseudoplastic fluids. Material may not be quite practical, but useful in understanding basic knowledge to someone interested in the subject.

Chemical Engineering magazine has also issued articles on non newtonian flow.

I think Q=AV (vol flow=section*velocity) is valid for any incompressible fluid, including pseudoplastic.

Note: V represents the 'average' velocity. For viscus flow this is 0.5 of the max velocity occurring at center of pipe, for turbulent flow this ratio is about 0.8 (both referring to newtonian fluids) - Colulson and Richardson's Volume 1.

Edited by kkala, 05 March 2013 - 04:21 AM.

[TS1979]

It is very doubtful that the fluid with that viscosity can be transferred through pipeline. You may need to add solvent to reduce the viscosity.

[kkala]

In a case of a thixotropic slurry (not pseudoplastic), the suspension was well "agitated" to lower viscosity through shear (1991). If I remember well, chemicals were also added for pumping it few kilometers off.  Of course this was a different case <http://www.cheresour...opic#entry69715>.

[Raj Mehta]

I think the following link would be helpful to you. (Pg-571 onwards)

http://books.google....plastic&f=false


Thanks,

Regards
Raj Mehta

[akloser]

It is very doubtful that the fluid with that viscosity can be transferred through pipeline. You may need to add solvent to reduce the viscosity.

 

TS1979, i ve seen transfer of polymer solution via rotary pump, having viscosity more then 10000 cp.

Ankur, this link is very useful.