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

JS
Thermometers or thermocouples are used in the batch and
thermocouples are also used for the jacket space temperature.
If the wall temperatl~e is desired the junction of
a thermocouple is soldered or peened into a small groove
in the vessel I'Jall (or coil). The surface is sanded smooth
and the wires lead out of the vessel through the liquid and
out the top_
If a jacketed vessel is equipped with a coil, steady
state experiments can be made 'tvi th the heating (or cooling)
rate of the jacket balanced by the cooling (or heating)
rate of the coil ( 37~39).
The temperature of the jacket,
coil, and batch thus remain constant. Most authors, however,
have used an unsteady state method where readings of
the batch and jacket (or wall) temperatures were taken
versus time as the batch 14as heated, or cooled.
The latter
method has the disadvantage of changing fluid properties
Hhile the former has the disadvantage of not being able to
detel~ine
the heat transfer coefficients of a jacketed
vessel in which the flow patterns are not disturbed by the
presence of a coil. Balancing the heat transfer rates betHeen
the coil and jacket is also a time .... consuming task.
Calculation of Heat Jransfer Rate
The amount of heat Hhich is transferred per unit time
in the steady state system can be calculated from the product
of the enthalpy change of the medium in the jacket and the
flow rate of this fluid, the enthalpy change-flow rate product