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Product Viscosity Versus Shear

Feb 11 2013 06:50 PM | Steve Hall in Fluid Flow ***-- Share this topic:
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Shear Rate in Pipeline

The shear rate at the wall of a circular pipe is calculated with:

eq-8 Eq. (8)

And here are the results:

Table 4: Viscosity Results

Parameter

Test 1

Test 2

Flow rate

220 kg/min

160 kg/min

Density

1.26

1.26

Pipe diameter

47.5 mm

47.5 mm

Velocity

1.65 m/s

1.20 ft/s

Shear rate

277 sec-1

202 sec-1

Viscosity at 25°C

68 cP

83 cP

Corrected viscosity, 34°C

42 cP

53 cP

Compare with calculation

39 cP

47 cP

Discussion and Conclusions

After correction for shear rate and temperature, viscosity measurements from the Brookfield viscometer result in reasonably good estimates of pipeline pressure drop. It is important to ensure that the sample has reached the target temperature of 25° before recording the reading.

The limitations in this study include:

  • 1. Pressure gauge reading accuracy due to the range of the instrument and the relatively small value being read.
  • 2. Estimated placebo product density.
  • 3. Unknown dependency of viscosity on the time of the applied shear stress. Further measurements with the Brookfield viscometer could be made to determine if there is a time dependency.

 

References

iHall, S.M., Rules of Thumb for Chemical Engineers, Butterworth-Heinemann (2012)

iiSpecific gravity determined from the pump speed (40% x 449 rpm max) and capacity (0.96 l/rev). This gives volumetric flow rate. From the measured mass flow rate, the specific gravity is calculated. Results from the two flow tests were averaged to obtain a value of 1.26.

iiiBrookfield Engineering Labs, More Solutions to Sticky Problems, downloaded from http://www.brookfieldengineering.com/

ivPoling, B.E., Prausnitz, J.M., O’Connell, J.P., Properties of Gases and Liquids, Fifth Edition, McGraw-Hill (2001).





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6 Comments

Very good read.  I currently am working with a client in the ~400 to ~600 cP viscosity range.  This analysis will be very helpful.

 

Mark

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tarang.suthar
Apr 05 2013 11:29 AM

Please give me the Viscosity calculation in Excel sheet with various Ointment and other Viscous Material

Thank you, can you also include the schmatic diagram of the set up.

Is this excellent article available as a pdf download?

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Chris Haslego
Sep 11 2014 01:28 PM

Is this excellent article available as a pdf download?

Sent it to you via PM.

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techno_titan
Oct 27 2014 12:17 AM

Very interesting article. May I use this as a case study for teaching my fluid dynamics class?