Environmental Engineering Reference
In-Depth Information
Wind currents
Atmospheric inversion layer
CSTR
Valley
Stationary
source
Mobile source
FIGURE 6.27
A simplified well-mixed “box” model for an urban area nestled
between mountains (e.g., Los Angeles, CA).
the valley is
G(
m
3
/
h
)
=
U
(m/h)
WH
(m
2
) and
U(
m/h
)
=
GL/V
. Hence,
1
−
e
−
(G/V)
·
t
S
TOT
G
+[
A
]
0
e
−
(G/V)
·
t
.
[
A
]=
(6.133)
Let us take a specific example where
V
=
1
×
10
12
m
3
,
G
=
5
×
10
11
m
3
/h. CO input
by wind
=
2
×
10
6
mol/h, CO input by automobiles
=
1
×
10
8
mol/h, and [A]
initial
=
0.00025
N
CO,auto
= 1E8 mol ∙ h
-1
0.0002
0.00015
0.0001
5 10
-5
N
CO,auto
= 0 mol ∙ h
-1
0
0
2
4
6
8
10
t
/
h
FIGURE 6.28
Change in concentration of carbon monoxide with time in an urban
area as a result of automobile emissions. A comparison is made with one that is devoid
of automobile contributions.
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