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Advanced Topics In Exhaust/Intake Design
Ron Petersen, Ph.D., CPP,
Inc.
This presentation will address four aspects of exhaust and intake
design. These areas are: stack ganging, hiding air intakes, induced
air fan dilution and plume rise. "Stack Ganging" addresses
the results of an on-going ASHRAE research study with an aim to
provide guidance on locating low flow stacks next to high flow stacks
such that additional plume rise can be obtained. The talk will discuss
optimum fan arrangements for this situation so that the low flow
stack can remain at the same height as the high flow exhaust and
achieve the same plume rise. "Hiding Air Intakes" summarizes
another ASHRAE research study that showed by placing air intakes
on building sidewalls a significant decrease in exhaust concentration
can be achieved. Using this placement strategy, stack heights and
fan flows can be minimized thereby saving materials and energy costs.
The "Induced Air Fan Dilution and Plume Rise" area documents
why the extra dilution reported on by induced air fan manufacturers
should be disregarded when selecting a fan system. The main selection
criteria should be the plume rise that is achieved by the exhaust
fan. This discussion will help a designer select the fan system
that gets the most plume rise (i.e., lowest concentrations at air
intakes) for the lowest long and short term cost.
This presentation will also provide an overview of exhaust and
air intake design techniques that can be utilized to optimize the
performance of the exhaust systems to achieve adequate air quality
while minimizing energy costs. When the design of exhaust and air
intake systems are considered throughout the design process, starting
at master planning, there are often opportunities to design exhaust
systems that require only minimal stack heights and volume flow
rates. In advanced systems, the volume flow rate can even be allowed
to adjust to the variable HVAC loading of a typical laboratory building.
Variable air volume exhaust systems have been shown to significantly
reduce energy costs while maintaining adequate air quality.
Labs21 Connection:
Reduced operating costs - the information provided will help minimize
fan sizes and stack heights. This may result in lower energy and
equipment costs.
Improved environmental quality - the information provided will
help 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 - the methods discussed can be used
to educate the community and tell them the exhaust system has been
designed to minimize air quality impact.
Superior recruitment and retention of scientists - buildings that
have health or odor problems due to fume reentry will not promote
recruitment and retention. Application of the methods discussed
will help ensure problems do not occur after building occupancy.
Biographies:
Dr. Ron Petersen, Principal and Vice President of CPP, Inc.,
has over 30 years experience in exhaust/intake evaluations, air
quality assessments, atmospheric dispersion, snow deposition simulations,
wind-tunnel modeling and numerical modeling. Dr. Petersen has conducted
numerous studies related to exhaust/intake design and pollutant
transport in complex environments on laboratory projects at UC Irvine,
UCLA, UC Davis, UC Berkeley, Texas A&M, Cornell, NIH, CDC, Georgia
Tech, Colorado State University, Bayer, Amgen, Genentech and many
others. Dr. Petersen is a Certified Consulting Meteorologist and
is a member of several professional organizations including A&WMA,
AMS, AIHA and ASHRAE. He was the Chairman of the AMS technical committee
on Meteorological Aspects of Air Pollution and was the Technical
Program Chairman for the 9th Joint Conference on Applications of
Air Pollution Meteorology. He presented/prepared comments on behalf
of the Air & Waste Management Association's meteorology committee
at past EPA Modeling Conferences in Washington D.C. regarding revisions
to the EPA "Guideline on Air Quality Modeling." Over the
past five years, he has presented at the Laboratories for the 21st
Century Conference on topics related to exhaust and intake design.
In January of 2004 and 2006 he gave a short course for ASHRAE on
designing exhaust systems and regularly provides training for architects
and engineers on the topic through the educational organization
LABWIZE. He has authored or coauthored over 300 papers and technical
reports to include technical papers regarding wind-tunnel modeling
and optimum stack designs. Dr. Petersen has a Ph.D. in Civil Engineering
from CSU, and an MS in Atmospheric Science and a BS in Mathematics
from the South Dakota School of Mines and Technology.
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