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

45
The group to the left of the equal sign is called the
Nusselt number.
The first group to the right is the mixing
Reynolds number, the second is the Pr~ndtl
number, and the
third is a viscosity correction factor similar to the one
used by Sieder and Tate (181) in pipes..
Very fe1.o[ investigators
have studied the effects of the remaining groups.
The results of most of the vwrk done in the field of
correlation of heat transfer rates in jacketed agitated
vessels to Newtonian fluids can be sw~marized
2-36
by equation
NNU (2-36
A survey of the experimental conditions and correlation
results of the papers published to date for the jacket and
coil types of heat transfer surfaces Sh01'ITS
that the exponent
of the Reynolds nlwber is usually reported as 0.67 althol~h
it varies from 0.5 to 0.75.
Likewise, the exponent of the
Prandtl num.ber is usually reported as 0 .. 33 but varies from
0.25 to 0.50. The viscosity ratio exponent varies behJeen
o.lL~ and 0.90 with the majority reports about 0.14. The constant,
C, varies over a 1rlide r~nge-,
from .035 to 39 .. 0 and is
probably a function of the impeller type and system geometry.
One author (160) reports C to be a function of Reynolds
nlwber.
This function is different for each type of impeller.
Another author (137) reports that the exponent of the viscosity