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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