Document b5RKvV8wyonErnywqLexbGed1

688 CHAPTER 31 1951 Guide h0 -- friction loss under actual (operating) conditions, any consistent unite. he -- pressure loss due to sudden contraction, feet of fluid flowing. h0 = pressure loss due to sudden enlargement, feet of fluid flowing. hi = friction loss, feet of fluid flowing. K = regain in static pressure, feet of fluid flowing. h, -- friction loss under standard conditions, any consistent units. hr -- total dynamic pressure loss, feet of fluid flowing. k -- conductivity, Btu per (hour) (sq ft) (Fahrenheit degree per inch). L = additional equivalent length of duct for loss in elbows, feet; L/W and L/D = additional equivalent length in terms of width and diameter, di mensionless. I -- length of straight duct, feet. P =* perimeter of duct, feet. Qa = air quantity, cubic feet per minute. Qw = heat loss through duct walls, Btu per hour. R =* centerline radius of elbow, or vane radius as noted, feet. R/W and R/D = radius ratio, dimensionless. - r = loss through specified duct sections, inches of water. ti = temperature of air entering duct, Fahrenheit degrees. t* -- temperature of air leaving duct, Fahrenheit degrees. U = temperature of air surrounding duct, Fahrenheit degrees. XJ = thermal transmittance coefficient, Btu per (hour) (square foot) (Fahrenheit degree). + V = mean velocity of standard air, feet per'minute. Vm -- mean velocity of air or fluid, feet per minute. v Vi = mean velocity of standard air in inlet duct section, feet per minute. Vt = mean velocity of standard air in outlet duct section, feet per minute. v = mean fluid or air velocity, feet per second. vi ~ mean velocity in inlet duct section, feet per second. vt -- mean velocity in outlet duct section, feet per second. W *= duct dimension in ulane of bend, feet. w = weight rate of air now through duct, pounds per hour. x = thickness, inches. REFERENCES 1 A.S.H.V.E. Research PaperNo, 1280--A New Friction Chart for Round Ducts, by D. K Wright, Jr. (A.S.H.V.E. Transactions, Vol. 51,1945, p. 303). Friction Factors for Pipe Flow, by L. F. Moody (A.S.MJE. Transactions, Vol. 66, 1944, p.671). 8 See Chapter I for definition of standard air. 4 Friction Charts for Gases Including Correction for Temperature, Viscosity and Pipe Roughness, by R. D. Madison and W. R. Elliot (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, October, 1946). Friction Equivalents for Round, Square and Rectangular Ducts, by R. G. Huebscher (A.S.H.V.E. Journal Section, Beating, Piping and Air Conditioning, Decem ber, 1947). Winter Air Conditioning, by S. Konzo (National Warm Air Heating and Air Con ditioning Association, 1939, p. 363). ' 7 Modern Air Conditioning, Heating and Ventilating, by W. H. Carrier, R. E. Cherne and W. A. Grant, 1940, p. 234 (Pitman Publishing Corp.). - 8 Heating, Ventilating and Air Conditioning, by L. A..Harding and A. C. Willard, 1932, p. 673 (John Wiley and Sons). 9 A.S.H.V.E. Research Report--Energy Losses in 90-Degree Duct Elbows: A Survey and Analysis of Available Information, by D. W. Locklin (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, September 1950, p. 138). 10 Pressure Loss in Ducts with Compound Elbows, by J. R. Weske (National Ad visory Committee for- Aeronautics, Advance Restricted Report W-39,'February*1943): -u Pressure Losses in Rectangular Elbows, by R. D. Madison and J. R. Parker (Heating, Piping and Air Conditioning, July, p. 365, August, p. 427, September, p. 483,1936). - u Fittings Losses for Extended-Plenum Forced Air Systems, by H. H.-Korst, N. A. Buckley, S. Konzo, and R. W. Roose (A;S.H.V.E. Journal Section, Heating, Pip ing and Air Conditioning, February 1950, pp. 111-118. . Air Duct Design 689 u A.S.H.V.E. Research Report No. 1216--Effect of Vanea in Reducing Loss in Elbows in Seven-Inch Square Ventilating Duct, by M. C. Stuart, G. F. Warner, and W. C. Roberts (A.S.H.V.E. Transactions, Vol. 48,1942, pp. 409-424). 14 Pressure Losses Due to Bends and Area Changes in Mine Airways, by G. E. McElroy (U. S. Bureau of Mines, Information Circular I.C. 6663, p. 4). 18 Pressure Losses Resulting from Changes in Cross-Sectional Area in Air Ducts, by A. P. Kratz and J. R. Fellows (University of Illinois Engineering Experiment Station, Bulletin No. 300). 14 Fan Engineering, (R. D. Madison, Editor) 5th ^d., 1948, pp. 124-128 (Buffalo Forge Company). 17 Design of Power Plant Installations: Pressure-Loss Characteristics of Duct Components, by J. R. Henry (.National Advisory Committee for Aeronautics, Advance Restricted Report L4F26, June 1944, L-208). 18 Air Conditioning Principles, by C. O. Mackey, 1941, p. 158 (International Textbook Company). 19 Fluid Mechanics, by R. C. Binder, 1943, p. 152 (Prentice-Hall). 89 Modern Diffuser Design, by G. N. Patterson (Aircraft Engineering, Sept., 1938 p. 267) and The Design of Airplane Ducts, by G. N. Patterson (Aircraft Engineering July, 1939, p. 263). 81 Duct Sizing with Partial Static Regain, by R. H. Anderegg and F. W. Hutchin son (Heating, Piping and Air Conditioning, August, 1946, p. 97). 88 Power Savings Through Static Pressure Regain in Air, DuctB, by J. R. Fellows (Heating, Piping and Air Conditioning, April, 1939, p. 219). 83 Standards of the National Board of Fire Underwriters (N.BJF.U. Pamphlet No. 90,-p. 21). 84 Design of Air Conditioning Systems for Low Maintenance, by M. G. Kerahaw (Refrigerating Engineering, October, 1946, p. 315). 85 Clean Your Ducts, by G. L. Candler (Heating, Piping and Air Conditioning, July, 1947, p. 83). 88 Duct Leakage and Job Revision, by E. L. Schulz (Heating and Ventilating, October, 1944, p. 83). BIBLIOGRAPHY FLUID FIX)W (See Chapter Jf)' Engineering Applications of Fluid Mechanics, by J. C. Hunsaker and B. G. Rightmire, 1947 (McGraw-Hill Book Company, Ino.). Elementary Mechanics of Fluids, by Hunter Rouse 1946. Inc.). (John Wiley & Sons, The Flow of Liquids, by W. H. McAdams (Refrigerating Engineering, February, 1925, p.279). --- The Flow of Fluids in Closed Conduits, by R. J. S. Pigott (Mechanical Engineering, Vol. 55,1933, p. 497). A Study of the Data on the Flow of Fluids in Pipes, by E. Kemler (AJ5.MJ5. Transactions, Vol. 55,1933, Hydraulics, p. 7). '- Mechanical Similitude and Turbulence, by T. von Karman (translated and re printed as Technical Memorandum N.A.C.A. No. 611,1931). Turbulent Flow in Pipes, with Particular Reference to the Transition Region Between the Smooth and Rough Pipe Laws, by C. F. Colebrook (Journal, Inetitute of Civil Engineers, Vol. II,1938-39, p. 133). Evaluation of Boundary Roughness, by H. Rouse (Proceedings Second Hydraulics Conference, University of Iowa, Bulletin 27,1943). FLOW OF AIR IN DUCTS Frictional Resistance to the Flow of Air in Straight Ducts, by F. C. Houghten, J. B. Schmieler, J. A. Zalovcik, and N. Ivanovic (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 35). Analysis of Factors Affecting Duct Friction, by J. B. Schmieler, F. C. Houghten, and H. T. Olson (A.S.H.V.E. Transactions, Vol. 46,1940, p. 193).