ChE 150B
Problem Set 3
Due Wednesday, September 16, 2009
Problem 1. (25 Points) This problem is a continuation of Problem 5 in Problem Set 2.
To
proceed, you will need to solve the differential equation obtained that was derived for
absorption into a falling film together with the appropriate boundary conditions in order
to obtain the concentration and flux profile in the xdirection at various values of length
(z) in the film.
The following parameters are relevant to this problem:
9
2.1 10
AB
D

=
⋅
m
2
/s
0.5
L
=
m,
4
5.0 10
δ

=
⋅
m
1000
ρ
=
kg/m
3
0.001
μ
=
kg / m / s
1
A
p
=
atm
0.78
H
=
atm m
3
/ mole
(a) What are the concentration profiles, c
A
(x), and flux of A N
A
(x = 0), at the surface
of the film for values of z equal to 0.25 and 0.5 m?
You may assume that v(x) ≈
v
max
.
(b) Does your solution correspond to the case where the assumption of penetration
theory is valid?
Be sure to explain your answer.
How does your answer depend
on the values of
δ
2
/D
AB
?
Why is this ratio relevant?
Problem 2.
(30 points) Liquid benzene leaked from a storage tank and seeped into the
ground below.
Since the density of benzene is less than the density of water, the liquid
benzene formed a light nonaqueousphase liquid layer on top of the watersaturated solid
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 Winter '08
 Pines
 Solubility, Partial differential equation

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