Page 21 - Packed bed columns for absorption, desorption, rectification and direct heat transfer
P. 21
16
^
dQ = if 0 + B" + ^)dx.dy.dz.dt. (37)
Since
= dV, (38)
where rfF is the volume of the parallelepiped, Eq, (38) can be written also as
follows:
The expression in brackets is the Laplace operator
4 4 ',. (40)
2
a
ebe dy 2 dz = V
Thus
3
(41)
According to the low for conservation of energy the change of the
energy in the parallelepiped leads to a change of the temperature in it.
c.p.dV—dt (42)
dr
— d t is the change of the temperature of the parallelepiped for time dr.
dt
From Eqs. (41) and (42) it follows:
