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Computer Aided Duct Design
Abstract
The circular slide rule is the industry standard for
duct design. It is the simplest, most convenient way to
take into account the many variables of ductwork
analysis. The slide rule, however, is also relatively
inaccurate. This means the ductwork is designed with
a higher static pressure and greater noise and
turbulence than is necessary. A computer model helps
to resolve these problems, reducing the fan horsepower
needed to deliver the air. Computer optimization also
reduces noise and the high rate of heat transfer
caused by turbulent flow in abrupt dynamic
transitions. The result is energy savings at the fan,
chiller and boiler. There are also first cost savings
because of smaller ducts and transitions.
The design screen of the computer program is a simple
Cartesian coordinate system with velocity and static
pressure as the axes. A userdefined target curve is
plotted on this background and each segment of the
duct is plotted on the graph to permit a close
approximation to the ideal, which is a uniform rate of
charge in velocity and static pressure. Different duct
sizes for width and depth of each section can be tried
by the user until the best combination is attained.
Other controls are built into the program, such as
office standards for minimum duct size or minimum
charge in width and height. The program is flexible,
convenient and accurate. It generates a thorough data
and graphical report for reference and evaluation.
Citation
Clark, W. H. (1994). Computer Aided Duct Design. Energy Systems Laboratory (http://esl.tamu.edu); Texas A&M University (http://www.tamu.edu). Available electronically from https : / /hdl .handle .net /1969 .1 /6625.