Document EmBg5YBB9LJeJjyQDp7vQXDGL

552 CHAPTER 29 post No. 12251--Performance of side outlets'on horizontal'ducts (ASHVE TsAifBACnoHS, VoL 49,1943, p. 58). . - V. *. - Other Papers Presented at ASHVE Meetings,. i ' D. J. Stewart and GJ F. Drake: ASHVE Bssbabcb Rsfgbt No. 1051--The '.'noise characteristics df 'air supply outlets (ASHVB'TiUNSAdnoira; VoL 43; 1937/p,:81). ' R. A. Nielsen: ASHVE. Ressabch Roost No/liSS^-Dirt patterns on walls (ASHVE Tbansactions;'.Vo1.46,- 1940, p. 247). G. S. Dwjphinee and'Peter Argeutieri:1'ASHVE Research Repost No: 1361--Balancing 'air delivery of a system of manifold air diffusers (ASHVE Transactions, Vol. 55,1949, p. 213).' ' *' S. F.- Gilman/ H. E.1 Straub, :A, E.;'Herflhey/ and R. B. Faigdahf: ASHVE Refobt No.- 1471--Room air dial tribution research for year 'round air conditioning Part I--Sup- ply outlets' at one high' sidewall location! (ASHVE:Tbansac- tions, Vol. 59,1953, p: 151). '- -V - H, E.Straub'aad'B; y, Gilman:; ASHVE Bfsrarcb Report No. 1504--Room air distribution research for year 'round air- conditidnmE,- 'Paft ;II^-Supply-outleta at >three floor: locations (ASHVE IttANSAcnoKS, VoL 60, 1954, p. 249).- - .. - . H. G. Elrod, Jr.: ASHVE Rsssabcb Repost No. 1514--Com-:' putation-.chartajand' theory, for rectangular.'and circular jets (ASHVE Transactions, M60.-1954, p:431). .;j.j .. -, 1965 Guide< And Dato BooK Miscellaneous Articles v;` G. L. Tuve: Measuring air distribution and grille perform-' ance in air conditioning (ASHVE Journal Section, Heating, Piping and Air Conditioning, November 2937, p. 700). F. F. Stevenson: Air discharge from narrow dots {Heating,. Piping and Air Conditioning, May 1941, p. 308, and June 1941, pi 368. Discussed by. J. R. Feilowa and D, W. Nelson, hoc. dt, September 1941/p. 558 and 559). - Sturm: Vertical air distribution.in tall buildings (Heating, Piping and Av Condiliomjig, June 1947, p. 69 ana-September 1947, p. 93). 'L. R: Phillips: Balancing an air. conditioning system (Re frigerating Engineering,'July 1950, p. lll). ' . What is a draft? (Heatmg.'Pipmg.'and Air Conditioning, May 1951, p. 67; July 1951,' p. ,71 /'September 1951, p.' 69;' January 1952, p. 113; March 1952, p. 73).* "1 /.* . .. ; Seven questions on duets and grilles (Heating, Piping and Air Conditioning, May 1952, p. 106 and July 1952, p. 111). R. V. Martelli and H.. O. Scarletti'. Air distribution studies (Heating. Piping,and Air Conditioning, November 1952, p.-77. Discussed byWiO: Huebner, lie. cit, January '1953, p. 119 and by. the'authors,. March 1953, p!'85). CHAPTER 30 AIR-DIFFUSING EQUIPMENT Supply Air Ouf/efs, Procedure for Ouf/ef location and Selection, Noise Confro/; Grille Outlets, Applications, Accessory Devices, Specia/ Construction features; Slot Oiffuser Outlets, Applications, Accessory Devices, Special.Construction Features,- Ceiling Diffuser Outlets, Applications, Accessory Devices, Special Construction Features; Return and Exhaust Air Intakes,. Grilles and Registers, Equipment for All-Air High-Pressure Systems, Types of Equipment, Pressure-Reducing Valves, Single-Dud Terminal Units, Dual-Duct Terminal Units,' Constant Volume Control, Static Pressure Control, High- ' , Capacity Dual-Duct Units THE function-'of the'supply outlets,-or the air diffusing equalization than slot diffusers. Grilles and registers which equipment, is to introduce the supply air into the condi have a long throw, have the lowest diffusion and induction tioned space to obtain the desired indoor atmospheric environ rate. Therefore, round or square ceiling diffusers will deliver ment Return and exhaust air is removed from the space more air to a given'space than other types of equipment in through return and exhaust intakes. Various types of diffusing those cases where recommended residual velocities (25 to 35 equipment are available as standard equipment This chapter fpm) are required. In some spaces,.higher residual velocities describes this equipment and discusses its proper use.- Refer to can be tolerated or the ceilings may be high enough to permit a Chapter 29, Space Air Distribution, and Chapter 31; Air Duct lower diffusion rate. Design. 1 .... Outlets with high induction characteristics can also be used SUPPLY AIR OUTLETS. to advantage in summer air-conditioning systems with low supply air temperatures and consequent high temperature Supply outlets are important parts of-wann air'heating, ventilating, and air-conditioning systems. The correct types of outlets, - properly sized and properly located, control the air pattern within the space and obtain proper air motionand temperature equalization in the occupied zone. Unsatisfactory conditions result if the air is pooHy distributed. ' ' -' Three bade types of supply outlets are commonly available: (1) grille and register outlets, (2) slot diffuser outlets, and (3) ceiling diffuser outlets! These outlets have different'construc tion features and physical configurations, and differ in their performance characteristics (air pattern). differential between room air temperature and supply air temperature. Therefore, ceiling diffusers may be used in sys tems with cooling temperature differentials up to 30 to 35 F deg and still provide'satisfactory temperature equalization within toe space, if the system is carefully designed: Slot diffusers may be used in systems with cooling temperature differentials as high as 25 F deg under favorable conditions; but in general they should not be used in systems'with tem perature differentials of,more than 20 F deg. Grilles and registers may be used in well designed systems with cooling temperature differentials up to 25 F deg. \i Accessory devices used in connection' with these outlets regulate toe "volume of toe supply air and. control :its flow pattern. The outlet cannot discharge air properly , and uni formly, unites the air is conveyed to-it ma'ufiiform-flow. Accessory devices are also necessary for proper lair'distribution in the space, and they must be selected and used in accordance with manufacturers'1' recommendations.' Outlets * should- be sized to project the air in such manner-that its velocity:and temperature reach- acceptable levels before entering ` the occupied zone. : '"' '* The induction or entrainment characteristics of a moving air stream lead to a phenomenon sometimes referred to as surface effect. An air stream moving adjacent to or in contact with a wall or wiling surface, creates a- low-pressure area im mediately adjacent to that surface, and part of its air is di verted into this low-pressure area, remaining in contact with the surface substantially throughout the length of throw. The surface effect counteracts the drop of horizontally projected air streams. . Ceiling diffusers exhibit the surface effect to a very high The three basic types of outlets vary widely in the manner in which they diffuse or disperse the supply air into the con ditioned space, and induce. or entrain .room air; into the primary air stream. degree, because the circular air pattern blankets the entire ceiling area surrounding the outlet. Slot diffusers, which dis charge the air stream across the ceiling, exhibit surface effect only if they are sufficiently long to blanket a- ceiling area Outlet types which have a high induction rate have short throw and rapid temperature equalization. Ceiling:diffusers large enough to produce the effect. Grilles and registers ex hibit varying degrees of surface effect depending upon toe a shorter throw and obtain more rapid temperature . The reneiml responatrility lor this chapter b trigged to TC 4.1, Duet D> (tod Roam Air Distribution. spread of the air pattern: In many installations, the outlets must be mounted on an exposed duct and discharge the air stream into free space. 553