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Modeling Exhaust Dispersion for Specifying Acceptable
Exhaust/Intake Designs
Ronald L. Petersen, Ph.D, CPP, Inc.
This presentation will describe a new Labs21 Best Practices guide
for modeling exhaust dispersion. Accurate modeling of exhaust dispersion
is needed to ensure concentration levels at air intakes and other
sensitive locations do not exceed health or odor limits. The methods
available for predicting exhaust plume rise and the concentration
levels at air intakes and other sensitive locations will be described
along with their advantages and disadvantages. The effects of building
shape, screens around the stack, intake location, volume flow, exit
velocity, chemical utilization, and local meteorology on exhaust
dispersion will also be discussed. A step by step approach is provided
that includes an initial qualitative assessment of the exhaust/intake
design, development of a minimum acceptable concentration for each
exhaust, predicting concentrations at intakes and other locations,
comparing the predicted concentrations against the criterion, and
modifying the design until the criterion is reached. Copies of the
Best Practices guide will be available.
Labs21 Connection:
Reduced operating costs. By using the appropriate modeling approach,
fan sizes and stack heights can be minimized which may result in
lower energy and equipment costs.
Improved environmental quality. Again, using the appropriate
modeling method will ensure that concentration levels due to laboratory
pollutants will not exceed health and odor limits at intakes and
other sensitive locations (entrances, plazas, windows, etc.)
Increased health, safety, and productivity. An accurate assessment
of the exhaust system will help ensure toxic or odorous fumes do
reenter the building through air intakes, windows or doors.
Enhanced community relations. A knowledge of the air quality impacts
obtained through dispersion modeling can be used to educate the
community and tell them they are not at risk (if true).
Superior recruitment and retention of scientists. Buildings that
have health or odor problems due to fume reentry will not promote
recruitment and retention. The appropriate dispersion modeling analysis
will help ensure problems do not occur after building occupancy.
Biography:
Dr. Ron Petersen has a Ph.D. in Civil Engineering from Colorado
State University (Specialty in Wind Engineering), an M.S. in Atmospheric
Science from the South Dakota School of Mines and Technology and
a B.S. in mathematics from the South Dakota School of Mines and
Technology. Dr. Petersen is a Vice President and Principal at CPP,
a firm that provide wind engineering and airflow solutions for the
built environment. One of the areas that Dr. Petersen specializes
in is providing design information for new and existing laboratories
or hospitals so that the air quality impact of building exhausts
can be minimized at nearby air intakes and other sensitive locations
(i.e., operable windows, entrances, plazas, walkways, etc.). Some
of the projects he has worked on include NREL's new Science and
Technology Facility, Lawrence Berkeley's new Molecular Foundry,
CDC Building 110, Cornell's Duffield Hall, National Institutes of
Health Clinical Research Center, the UCLA Westwood Replacement Hospital,
M.D. Anderson Cancer Research Center in Houston and the Fred Hutchinson
Cancer Research Center in Seattle. He also was the principal investigator
on two past ASHRAE research projects and one on-going project. The
first project developed general exhaust stack guidelines to account
for the effect of architectural screens. The second project looked
at the benefit of hidden versus visible air intakes. The on-going
project's goal is to provide information regarding stack ganging.
Dr. Petersen is also actively involved in several professional
organizations to include AMS, ASHRAE, A&WMA, ISPE and AIHA.
In 1996, He has also served or is serving on committees related
to pollutant dispersion and fume reentry for ASHRAE, AMS and A&WMA.
Dr. Petersen has also presented a short course on fume reentry for
ASHRAE and AIHA and has presented at several past Labs21 Conferences.
He has authored or coauthored more than 300 papers and technical
reports including technical papers regarding minimizing pollutant
reentry into buildings. Much of this work was summarized in a 2002
ASHRAE Journal article.
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