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

11
Wa.ll (Mi€1dl~)
Same as #5
81
12
Bateh. (Middle)
Same as #0
The ahove €o~diti0~S a~~ly t@ all tke water rtlns. Whe~
usimg m0re viSCGUS flui€is seme vaFiati0nl im '!;,Jall temperat1ltre
was Boted and tke tkermocouple panel was modified so that
the taree wall therm.oeouples were eenneeted. Thus fer all
runs after run number 185 the ten~erature points 3, 5, 9
ane! 11 record the average of' the three wall temperatures
lIDO. :not the mdividual posi tioRs as give~ abcnre ..
Before the therr~oeouples were metalled they were
connected to 'the recorder and calibrated. They were placed
in iee water; a 25°c co~stant tem~erature bath, and boilimg
water. At all three temperatures the system reeorded the
exaet temperature, pr0vided the recorder was 1tJarrl1ed up for
f'ifteen m±nutes prior to measuring the temperature. I~
all the heat transf'er runs the reeoraer was therefore wa~led
up f'ar thirty minutes before data was takem. The chart
speed used was 0.5 mcnes per winute although 1, 2, 4 and 5
inches per minute were also available at the flick of a
switch.
The three wall-temperature ther.mocouples gave sligatly
tiiifferent temperatures at the Glifferent l@catiems. It was
found that the vertical loeation of the impeller was a large
faetor in the matnitude of the deviati6ns. T.me impeller
p0sitiens listed in Table 5-1 were exper~entally
determ~e~