Generic Guidance and Optimum Model Settings for the CALPUFF ...

long. Some of the buoyant emissions from the reduction process escape through a continuous
ridge ventilator, which is a few meters wide, running the length of the potroom. Most of the
emissions, however, are collected by hooding above the reduction cells and are treated and
exhausted through nearby stacks. There are typically 2 to 20 point sources, usually low-level, for
each potroom primary control system.
Since a buoyant line source has one less degree of freedom than an isolated point source in
entraining air, the plume rise will be enhanced. In addition, the line source rise will be dependent
on wind direction, line length, the number of parallel lines, and their spacing. Both the line source
and the short point sources are subject to building downwash effects.
3.5.1 Entering Line sources into CALPUFF
The coordinates of the beginning and ending locations of each line are used to determine the
points of release, and the orientation of the lines. In addition, for a group of such buildings, the
average source attributes are needed:
L the average building (line) length (m)
Hb the average building height (m),
Wm the average line source width (m)
Dx the average spacing between buildings (m) and
F| the average line source buoyancy parameter (m 4 /s 3 )
Where
F| = g L WM w ( T s – Ta )
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Ts
And,
g is the gravitational acceleration (m/s 2 )
w is the exit velocity (m/s)
Ts is the exit temperature (K), and
Ta is the ambient air temperature (K)
The buoyancy parameter is computed for each line and then averaged.
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