Prediction of batch heat transfer coefficients for pseudoplastic fluids ...

2S
The results shm-red that equation 2-19 1"a3 valid and Kg
equalled 13.0. Godleski and Smith (75), Metzner, et al. (122),
and Calderbank and Moo-Young ( 34) as 1mll as the data of
Foresti and Liu (65) support fietzner and otto's conclusion
that the shear rate can be expressed by equation 2-19,
1..rith I~s
betifTeen 10 .. 0 and 13.0. l.Jfetzner et al (J2?) made the
most extensive study and, based on their 1-rork and the others
given abov~ report that in an agitated vessel the shear
rate at the impeller can be expressed as
(2-20
for these conditions:
1. Baffled and unbaffled vessels.
2. For pseudoplastics "Ti th flow behavior index bet'Heen
0.16 and 1.0 ..
3. Tank dia..."'1leters. 0.5 to 1.83 ft.
4.. Impeller diameters.. 0 .. 167 to 0.67 ft.
5. 'rank diameter/Impeller diameter. 1 .. 3 - 5.5 (laminar
region) 2.0 - 5.5 (transition region)
6. Impeller speeds 0.5 to 29 rev./sec.
7. Flat bladed turbines, fan turbines, ~nd marine
propellers.
8. For dilatant fluids up to n :: 1.5 if the nu/Da is
greater than 3.0.
For dilatant fluids "Ii th Dt/Da less than 3 .. 0 the shear