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100 CHAPTER 6 P. Gtootenhois: A ccrraiation of the resistance to airflow of wire gauzes (Proceeding*. Institution of Mechanical Engineers, VoL 1, 1954, p: 837).'- ->' G. L Taylor R. M. Davies: The Aerodynamics of Porous Sleets (Aeronautical Research Council, Reporta and Memoranda No. 2237, April 1944). L.' S. Toag: Hcat Transfer and-Friction Characteristics of Screen Matrices at High Reynold's Numbers (Stanford Univereity Dept: of Mechanical Engineering, Technics! Report No. 28, April 1956).: . A. E. Abramson: Investigation of annular liquid flow with eo- eurreht ' airflow 1 in horizontal tubes (Journo! ef Applied Me* <Amte*,;September l952, p. 267). * O. Baker: Simultaneous flow of oQ andgaa (Oil and Qua Jour* naL July 28,1954, p. 185). C.E..Dengler: Heat Transfer and.Pressure Drop.forEvapo* ration of Water in Vertical Tubes (PhJ>.- Them, Massachusetts 1965 Guide And Data Book Institute of.Technology, 1952)..-., -**** ;r . . W, L. HoDaday: Determiningjnessuie drop in;Freca-systems (RarHioEHA-nNo EwomKSBiwo, September 1954, p/55).,.: ,v fL S.' Ibsen, R. H.' Moen, anaD; R.' Moaner: Two-Phase Pressure Drop (Atomic Energy Commission;Report No. 2994. November 1954); - - , S. Levy: Theory r& pressure drop and heat transfer for,annu lar steady-state two-phase two-component flow in pipes,(Prtv cttdihha, 2nd Midwestern Conference on Fluid Mechanics, 1952). R_ P. Stein et of: Pleasure drop'aud heat transfer tonob- boiling and boiling water in turbulentSow inan internally heated annulus (Chemical Engineering, Pcogrea Symposium Senes, VoL 50, 1954, P-280).. .................. J. C. Westmoreland-`Prediction'of the Pressure'Loss, and Density Factors for. Two-Phase Annular. Flow with or without Heat Generation (Atomic Energy Commission, Knolls Atomic Potoer,Lid>orati>ry,,Rep<iri_Tio.l792). j CHAPTER 7 PHYSIOLOGICAL PRINCIPLES Ot&sicaf Vitiation ofAir, Physical Impurities in Air, Thermal Interchanges Between the Body and Its Environment, tow- andHighTemperature Hazards, Acclimatization, Upper Limits of Heat for Men at Work, Hot Spaces, Assessment of Heat Stress, Dry-bofb Temperature, Effective Temperature, Wet-butb Globe-Temperature Index, Index of Physiological Effect, The ,5 Predicted Four-Hour Sweat Rate, Heat Stress Index, Environmental Conditions and Comfort AN' of physiological principles is essential jr\ in the proper design of air conditioning systems-for epn*gi intended for human occupancy. The term atr condi tioning, in ita broadest Bense, implies control of.any or all of the physic*! find chemical qualities of the air. As defined in Chapter 67, comfort air conditioning is the process of treating air so as to control simultaneously its temperature, humidity; Hoanlinpgs, and distribution, to meet the comfort require ments of the occupants of the conditioned space. CHEMICAL VITIATION OF AIR People living indoors bring about certain physical and nhiaminal changes in the air about them. The oxygen content of the air diminishes and the carbon dioxide increases, but thpsft changes are too slight to be significant except in air tight spaces as in submarines. Organic matter which is usually perceived as odors, comes from the body or`clothes; Moisture and heat are given off by the body. There is no evidence of any toxic volatile material given off by man to the ambient air. Stale air may be offensive because of odors and may induce loss of appetite and loss of energy. Ob jectionable body odors have the same effects. These reasons, whether esthetic or physiological, usually make it desirable in the design of air-conditioning systems to provide for the elimination or control of odors arising from occupancy, cook ing, or other sources. This may be accomplished by intro ducing odor-free air in sufficient quantities to,reduce odor concentrations by dilution to a level which is not objection able. Odor-free air may be outdoor air or air which has been cleared of odors by sorption, washing, or other'appropriate means. In the case of vitiation by a few hazardous gases such as carbon monoxide from heating, cooking, and' certain in dustrial processes, no satisfactory chemical treatment for the elimination of the impurity has been found. The only sat& factory solution is elimination at the source by local exhaust ventilation, or, if this is impossible, reduction to a safe concentration by dilution. (See Chapter 11). In tire case of contamination by other matter, including volatile vapors and gases, chemical treatment for the removal or reduction of the impurities has been made available through' air *tp*mhg methods, which are discussed in Chapter 36. TU general rmrtoaba&ty for this chapter b --to TC 1.4, Ftqr otogj sod Su&ufi hovixovDOat- When the only source of contamination is the human oc cupant, and overheating is not a problem, the minimum quantity of odor-free air needed appears to'be that required to remove objectionable body odors or tobacco smoke. The con centration of body odor in a room, in turn, depends upon a number of factors, including the dietary and hygienic habits of the occupants (frequently reflecting their socio-economic status), the odor-free air supply, air space allowed per person, odor adsorbing capacity of air-conditioning processes,..and temperature and relative humidity. The intensity of odor sensation has been found to'vary as the logarithm of the con centration of the odoriferous substance in the air, or inversely with the logarithmic function of the amount of odor-free air supplied and the air space per person. The relation between air supply and occupancy has been studied by the Harvard School of Public Health1 and by the ASHRAE Research laboratory.* The data in Table 1 are for the removal of body odors under laboratory conditions.1 Table 3 of Chapter 27 gives minimum and recommended ventilation rates for various types of occupancies,'and includes.require ments for the removal of tobacco smoke.' - The total quantity of outdoor air to be circulated through an enclosure is often governed chiefly by the physical con siderations for controlling temperature, air distribution, and air velocity. Other factors which must be taken into con sideration include the type and.usage of the building, lo cality, climate, height of rooms, floor area, window area, extent of occupancy, and the operation of the system dis tributing the air supply. Frequently, some of these factors, particularly the need for air movement and good distribution, may tje satisfied by recirculation of inside air rather than outdoor air.^ - ....................... It will be noted that, with adequate air space, the rate of air change indicated in.Table 1 is from 4 to 30 cfm per per son. In rooms occupied by only a few persons, such an air change will be automatically attuned in cold' weather, by nor mal leakage around doors and'windows, and can .easily be secured in .warm weather by -the opening of windows.- With a space allotment of.400 cu ft per person,-only 1$ air changes per hour are necessary to-provide.a ventilation lateiof 10 cfm per person. Therefore, in the ordinary dwelling-with adequate-cubic space allotment, no special provision for controlling chemical purity of the air is necessary (aside from removal of fumes 101