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630 CHAPTER 31 1949 Guide ; BIBLIOGRAPHY ' Trend Curves for Estimating Performance of Panel Heating Systems, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 425). A.S.H.V.E. Research Report No. 1192--Panel Heating and Cooling Performance Studies, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 48, 1942,p. 35). A.S.H.V.E. Research Report No. 1193--Radiation as a Factor in the Feeling of Warmth in Convection, Radiator and Panel Heated Rooms, by F. C. Houghten, Carl Gutberlet and E. C. Hach (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 55). Panel Heating and Cooling Analysis, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 285). Operating Results of a Residence Radiant Wall Heating System, by E. J. Rodee (A.S.H.V.E. Transactions, Vol. 47,1941, p. 123). Performance of a Residential Panel Heating System, by H. F. Randolph and J. B. Wallace (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 235). Radiant Heating {Heating and Ventilating, March, 1941, p. 35). Radiant Heating and Cooling, by F. E. Giesecke (Heating, Piping and Air Condi tioning, June, July, August, September and October, 1940). Calculations for Radiant Heating, by T. Napier Adlam (Heating and Ventilating, October, 1931). Radiant Heating and Cooling, Part I, by C. O. Mackey, L. T. Wright, Jr., R. E. Clark, and N. R. Gay (Cornell University Engineering Experiment Station, Bulletin No. 32,1943). Design Method for Panel Heating Systems Using Copper Tubing, by R. G. Vaiiderweil (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, Nov. 1947, p. 123). Air Temperature Gradients in a Panel Heated Room, by J. M. Ayres and B. W Levy (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, Oct. 1947, p. 113). Graphical Solution of Radiant Panel Areas, by W. P. Chapman and R. E. Fischer (Heating and Ventilating, Jan. 1948, p. 88). Embedding Coils in Radiant Heating Panels, by D. L. Mills and L. J. LaTart (Heating and Ventilating, Dec. 1947, p. 75). Radiant Heat with Copper Tubing, by D. L. Mills and L. J. LaTart (Heating and Ventilating, Nov. 1947, p. 95). ' Panel Heat with Copper Tubing--Experiment in Practice, by D. L. Mills and L. J. LaTart (Healing and Ventilating, Oct. 1947, p. 65). Experimental Studies on Panel Heating Tube Spacing, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Journal Section, Healing, Piping and Air Conditioning, Aug. 1947, p. 111). Panel Heating--A Basic Discussion, by S. Konzo (American Artisan, Oct. 1946, p. 68). - . Solar House Heated by a Warm Air Floor Panel, by John E. Peterson (American Artisan, Dec. 1946, p. 83). Design Data for a Warm Air Floor Panel, by Axel B. Algren (American Artisan, Jan. 1947, p. 141). The Mechanism of Heat Transfer, Panel Cooling, Heat Storage, by Charles S.. Leopold (Refrigerating Engineering, July 1947, p. 33). Books Hot Water Heating, Radiant Heating and Radiant Cooling, by F. E. Giesecke, 1947 (Technical Book Co., P. O. Box 62, Austin, Tex.). Panel Heating and Cooling Analysis, by B. F. Raber and F. W. Hutchinson, 1945 (John Wiley and Sons, New York). Radiant Heating, by T. Napier Adlam, 1947 (Industrial Press, 148 Lafayette.St., New York). Radiant Heating, by R. W. Schoemaker, 1948 (McGraw-Hill Book Co., New York). Chapter 32 . FANS Classification, Performance, Efficiency, Characteristic Curves, System Characteristics, Selection of Fans, Fan Designations, Control, Motive Power, Attic Fans IN heating, ventilating, and air conditioning practice, fans and blowers are used to produce air flow. All fans or blowers are classified according to the direction of air flow through the fan with relation to the axis of rota tion and are either of the (1) axial flow.or propeller type, in which the-flow is parallel to the axis, or (2) radial flow or centrifuged type, in which the flow is at right angles to the axis. Axial flow fans are made in various designs and sizes. The form and. number of blades may vary for impellers of the same or different diameters. The blades may be of uniform thickness and made of cast or sheet metal, and either flat or cambered or of screw form; or they may vary in thickness, in the latter case usually being designed to conform to so-called air/oiZ sec tions of known characteristics, similar to those which have been developed for airplane propellers. Likewise, blade angle, or the angular relation of the blades to the plane of rotation, varies over a wide range. For opera tion against comparatively high pressures, it is customary to resort to en larged hubs in proportion to fan diameter (large hub ratio) and correspond ingly short blade length. The term disc fan has sometimes been loosely applied to such large hub fans, though it has long been generally used in con-. nection with any propeller fan of comparatively short axial length' whose' blades are relatively flat; in other words, for fan wheels which occupy a space which is more or less disc-shaped. Single stage air foil axial flow fans can operate at pressures up to 4 in. at a quite low noise level and, at considerably higher pressures, they are comparable in regard to noise to the centrifugal fan type. Radial flowot centrifugal fans used in heating, ventilating, and air con-, ditioning practice, are in general of two types; one with forward-sloped blades, and the other with backward-sloped blades. Many modifications may be made in the proportions, the curvature, and the slope or angularity of the blades. The slope or angularity of the blades determines the operat ing characteristics of a fan; a forward-curved or sloped blade is found in a fan having low speed operating characteristics, while a backward-curved or sloped blade is found in a fan having higher speed operating characteris tics. A wide variety of heating, ventilating, and air conditioning systems creates a wide variety in the demands that have to be met by the fan or blower. . The requirement may be to move small or large quantities of air against little or no resistance, or. to move small or large quantities of air; against higher resistance. Between the two limits innumerable specific' requirements must be met. Although fans of any class in either of the two general types can in general be made to perform the same duty, certain factors such as mechanical difficulties, space and noise limitations, efficiency and power limitations will usually determine the selection. : 631 S'