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

133
producibility was about ± 2 percent and for heating about
± 4 .. 5 percent.. ~Jhile this data may not be statistically
significant it roay give some idea of the reproducibility of
the present data.
The merits of calculating the heat transfer rate from
the temperature rise of the batch and the heat transfer
coefficient using wall thermocouples have been thoroughly
discussed in Chapter 2.
The Ne1.,.Jtonian fluid heat transfer data Has compared
to the currently accepted correlations in the literature.
The correlation for anchor agitators developed by BrOi"Jil et
13.1. (32) i>Jas used to calculate predicted Nussel t numbers
for the anchor data developed in this thesis. The actual
measured Nusselt numbers are compared with the predicted Nusselt
numbers in Figure 6-1.
Most of the data points show a good
comparison although on a fe1>J points for the heating of glycerine
the measured Nusselt nU111bers are much greater than predicted.
The arithmetic average deviation of all the points is ± 16 .. 6
percent.. The one factor ""Thich would cause the larger deviations
in the glycerine data ",muld be Bro",m's use of 0 .. 14.
for the viscosity ratio exponent.
The use of a higher exponent
as suggested by Uhl (194) Hould probably reduce the
error greatly.
It must be noted here that Brown did not
measure the effect of viscosity but accepted Chilton's value
of 0.14.