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

'11
The flow behavior index and fluid consistency index
expressed i~ the proper units are given iE. Table A-8. The
data are pletted in Figures A-4, A-5 and A-6.
li~es
The solid
are the values for the shear stress calettlated using
equations A-9 and A-IO with the constants in Table A-6 while
the plotted points are the data from which the constants
were es.leulated ..
The effects of turbulence were noticed when measur~
the 0.15% Carbopol at high speed. H.:noJever, these r'llE.S were
then redone using a smaller diameter spindle as suggested
in. Chapter 2.. . The data Has also che eked .for tem]5erature
rise due to heat generation..
The heat generated per unit
vol~ can be calculated using equation 2-16.
""""',..}J
Heat Generation = / ~ (2-16
The most viscous fluid at the highest shear rate generated
8 .. 31 x 10- 5 cale/see.. A series of measurements at aay one
tem.1gerature at any s]'ced took about five minutes at the
longe s t. This amoUJ:71.ts to a maximum temperature rise of
0.025°0. which is negligible. Not only was this rise
calculated on the basis of the conditions most prone to give
I
hi~~ rates of heat generation, but alsG the system was considered
to be adiabatic, whiCh is untrue..
did not influence the rheological :m.easurem.emts ..
Thus, heat generation
The torque required to rotat~
the spindle at a constant