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Computer Aided Duct Design
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.
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