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

CHAPTER I
INTRODUCTION
BATCH HEAT TRANSFER
Heat transfer from one fluid through a wall to another
fluid is usually described using an overall heat transfer
coefficient, U.
dq := UdA6To (1-1
where q is the amount of heat transferred through heat
transfer area dA.
The driving force,.6 To, is the overall
or total difference in temperature bettr-J8en the hot and
cold fluids. The reciprocal of the overall heat transfer
coefficient is the sun of all the resistances to heat
floWe
Equation 1-2 defines the overall heat transfer
I :=l+l+L 1
1 U 11m hf kw + h (1-2
coefficient for a jacketed vessel where h m is the coefficient
of heat transfer of' the fluid heat transfer medium.
Its
reciprocal is thus the resistance of this fluid to the flow
of heat. ~f
is the resistance due to the fouling of the
heat transfer surfaces. L is the thickness of the wall
and kvJ is its therm.al conductivity. The
resistance to heat flow due to the l-Jall.
ratio, {r is the
-1.v
~ is the resistance
on the batch side of the heat transfer surface and h is
called the batch heat transfer coefficient.
In many cases the batch heat transfer coefficient
is small and tkus is a controlling factor determining the