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

2
value of the overall heat transfer coefficient. The
agitation of the fluid, the system geometry, and the fluid
properties determine the value of the batch heat transfer
coefficient.
NON-NE1'ITONIAN FLUIDS
Hany factors may influence the behavior of fluids under
shear..
'remperature and pressure influence the viscosity
of fluids; the temperature effect is large and the pressure
effect small.
Newton postulated that for fluids at constant
temperature and pressure the rate of shear is directly proportional
to the shear stress. Subsequently, many fluids
Here found and studied 1.Jhich did not conform to Newton T s
theory.
The duration of shear, the shear rate, or the previous
history of the fluid influenced the shear stress required
for a particular shear rate..
All of' these fluids ltJere given
the npJl1e non-Nelliftonian.
Non-Newtonian behavior is fou-nd in two basic types of
fluid systems (118):
1. Solutions or melts of high-molecular Height
pol}Dneric materials.
2.. Suspensions of liquids or solids in a liquid
medium.
In general the degree of non-NeHtonian behavior increases
Hith the concentration of the polymer or disperse phase.
A large fraetima of non-NeHtonian fluids are classed