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

3
as pseudoplasticso
Pseudoplastic fluids exhibit shearthirLYling
flm.; behavior.
As the shear rate is increased
the shear stress required to provide the shear rate does
not increase proportionately.
Thus, as the shear rate
is increased the apparent viscosity (the ratio of the
shear stress to shear rate) decreases.
PURPOSE .. OF_T~~JS
A large f"PI!I..~ttml
of .fluids nOH handled indus trially
are nOn-N81f\rtonian and a large percentage of these are
pSeUdOl)lastics.
The design correlations developed for
Nei:ltonian fluids carLnot be used for pseudoplastics because
of the variable viscosity of the latter. In recent years
many authors have contributed to the development of design
equations for pseudoplastic fluids.
These equations have
been in three main areas:
1. Fluid flO1tJ, including friction factors for
isothermal and non-isothermal flOl-1!1 entrance
effects, kinetic energy, and onset of
turbulence.
2. Heat transfer in pipes.
3. POHer requirements in agitated vessels.
Much of this material is reviewed in the literature. (118,
120, 121, 190, 213).
To date, only tvJO papers have been published on the
prediction of batch heat transfer coefficients to pseudo-