Handbook of air conditioning and refrigeration / Shan K

17.78 CHAPTER SEVENTEEN
REFERENCES
Standard 111-88, the Associated Air Balance Council (AABC), and the National Environmental
Balancing Bureau (NEBB) all adopted the log Tchebycheff rule for rectangular duct and round duct
transverse, as shown in Fig. 17.32a and b, because this rule provided greatest accuracy. The reason
is that the location of transverse points of these rules has taken into account the effect of the duct
wall friction and the reduction in velocity near the duct walls. For round duct transverse, the log
Tchebycheff rule and log-linear transverse method are similar. Refer to ASHRAE Standard 111-88
for details. The log Tchebycheff rule was developed by a mathematician named Tchebycheff in
1977.
In MacFerran (1999), airflow in ducts measured by the equal-area method was often higher than
correct results, from 7 percent higher maybe up to 25 percent higher.
When the velocity pressure is measured, in inches WC (Pa), the air velocity, in fpm, can be calculated
from Eq. (17.10). For SI units, the air velocity, in m/s, can be calculated from Eq. (17.9), in
which g c � 1.
Amistadi, H., Design and Drawing Software Review, Engineered Systems, no. 6, 1993, pp. 18–29.
ASHRAE, ASHRAE Handbook 1996, HVAC Systems and Equipment, ASHRAE Inc., Atlanta, GA, 1996.
ASHRAE, ASHRAE Handbook 1997, Fundamentals, Atlanta, 1977a.
ASHRAE, Duct Fittings Loss Coefficient Tables, Atlanta, 1997b.
ASHRAE, ASHRAE/IESNA Standard 90.1-1999, Energy Standard for Buildings Except Low-Rise Residential
Buildings, ASHRAE Inc., Atlanta, 1999.
Behls, H., Balanced Duct Systems, ASHRAE Transactions, 1978, Part I, pp. 624–646.
Brooks, P. J., Duct Design Fundamentals, ASHRAE Journal, no. 4, 1995, pp. 69–76.
Coe, P. E., The Economics of VAV Duct Looping, Heating/Piping/Air Conditioning, August 1983, pp. 61–64.
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Smooth and Rough Pipe Laws, Journal of Institute of Civil Engineers, February 1939, p. 133.
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Air Conditioning, August 1985, pp. 91–104.
Evans, R. A., and Tsal, R. J., Basic Tips for Duct Design, ASHRAE Journal, no. 7, 1996, pp. 37–42.
Habjan, J., Medium Pressure Duct Sizing and Design, Heating/Piping/Air Conditioning, December 1984,
pp. 95–100.
Heyt, H. W., and Diaz, M. J., Pressure Drop in Flat Oval Spiral Air Duct, ASHRAE Transactions, 1975, Part II,
pp. 221–232.
Heubscher, R. G., Friction Equivalents for Round, Square and Rectangular Ducts, ASHVE Transactions, 1948,
pp. 101–144.
Idelchik, I. E., Handbook of Hydraulic Resistance, 2d ed., Hemisphere Publishing Corp., Washington, 1986.
MacFerran, E. L., Equal Area vs. Log-Tchebycheff, Heating/Piping/Air Conditioning, no. 12, 1999, pp.
26–31.
Miller, E. B., and Weaver, R. D., Computer-Aided Duct Design in a Small Engineering Office, ASHRAE Transactions,
1978, Part I, pp. 647–664.
NFPA 90A, Standard for the Installation of Air Conditioning and Ventilating Systems, National Fire Protection
Association, Quincy, MA, 1985 ed.
North American Insulation Manufacturers Association, New Duct Liner Standard Addresses HVAC System
Challenges, Heating/Piping/Air Conditioning, no. 2, 1994, pp. 61–67.
Scientific Computing, Software Review: Up for Review (Again), Engineered Systems, no. 1, 1998, pp. 76–84.
Shitzer, A., and Arkin, H., Study of Economic and Engineering Parameters Related to the Cost of an Optimal
Air Supply Duct System, ASHRAE Transactions, 1979, Part II, pp. 363–374.
Spielmann, S., Check Your Basic Skill on Duct and Ventilation System Cleaning, Air Conditioning, Heating &
Refrigeration News, Feb. 24, 1997, pp. 3–5.