Document wDp5ZnDvqkodDY2K2jVQjwEa6

HEATINC VENTILATING AIR CONDITIONING GUIDE 1943 V Vacuum , cooling unit* 484 heating pumps, 282 control. 283 piston displacement, 284 heating systems, 276, 849 down-feed, 278 " unit heater connection, 433 Vacuum dryer, 746 Valve, valves. 365 angle. 366 automatic, 365 check, 365 control, 304 expansion, 488 flow. 289 gate. 365 globe, 365 reducing pressure. 301, 365 Vane, vanes, 593 Vaned outlets, 596 Vapor, vapors . heating system, 850 unit heater connection, 433 pressure, 850 ' Vaporizing oil burner, 216 Velocity, 850 exhaust grilles, 600 method duct design. 616 pressure, 850 return grilles, 600 Ventilation, 850 air conditioning units, 443 (Jairy barn. 772 garage. 773 hospitals, 702 natural, 765 general rules, 771 passenger bus in summer, 715 physiological objectives of, 65 railway passenger car, 711 state codes, 862 symbols for drawing, 859 . systems, 395 wind forces, 765 Ventilator, ventilators roof, 770, 847 r- unit. 435 - control. 662 ' .: Vertical blow unit heater, 428 Vertical openings, 126 sealing of, 126 Vibration, machine, 641 Viscons filters. 566 automatic, 567 ' impingement, 566 Vitiation of air, 41 Volume control, 414 furnace. 180 1 specific, 848 -- W Wall, walls heat flow through, 153 heat transfer coefficients, 115 infiltration through, 120 ^ time lag of solar radiation, 155 -i ---------- Warm air heating systems, 369, 383, 850 method of cooling. 394 panel heating, 807, 808 radiant heating. 807 radiators, 215 Washer, washers, 531 air, $43 Water atmospheric cooling equipment; 537 ' coils, 506 control temperature service, 839 cooled condenser, 490 ' unit conditioning. 445 corrosion treatment. 368 heater coal-fired, 838 > solar, 840 heating. 819, 835 make-up, 553 maximum, main temperature, 539 properties of, 482 supply piping, 819 allowance for fittings. 823 factor of usage. 820 . maximum flow, 820 4 pressure. 821 sizing down-feed systems, 827 sizing up-feed systems, 825 thermodynamics of, 1 . well, temperatures, 538 Water vapor, 6 saturation pressure, 6 specific enthalpy, 7 specific volume, 7 Welding. 345, 358 Wet-bulb temperature, 542, 850 (see Temperature) Wet return, 850 Wind, winds forces, 766 due to stackeffect, 766 natural draft equipment, 545 . - - selection of, velocity, 138 - Window, windows . - coefficients of transmission, 115 leakage, 121, 123 - ' solar radiation through, 154, 155 ventilators, 439 Winter air conditioning system-, 395 comfort zone, 59 freezing, equipment. 537 - Wound rotor motor, 689 Wrought-iron pipe, 345 . - _ -' . Wrought-steel pipe, 345. ' '' Year 'round air conditioning system, 395 . Zone control, 648 evaporative regulation, 50 Zoning, 412 ' < control, 648 " ' : dual duct, 414 multiple fans, 413 _ recooling, 413 reheat, 413 separating equipment, 413' ' y volume control, 414 . ' ... xxiv . h'.' fj L Chapter I THERMODYNAMICS OF AIR AND WATER MIXTURES Dry Air9 Specific Enthalpy, Water Vapor, Moist Air, Dalton9s Lavs, Humidity Ratio, Relative Humidity, Dew-point, Enthalpy, Thermodynamic Wet-bulb Temperature, Mollier Diagram, Typical Air Conditioning Processes, Adiabatic Saturation, Psychrometric Chart, Steady Flow Energy Equation, U. S. ' Standard Atmosphere THE working substance of the air conditioning engineer may be regarded, for the purpose of analysis, as a mixture of only two constituents, dry air and water. . The mixture may consist of two, and possibly three distinct phases, solid, liquid and vapor. The vapor phase is conveniently referred to as moist air and is regarded as a mixture of dry air and water vapor. DRY AIR Composition. . Dry air is itself a mixture of several gases, but' its composition is subject to such slight variation that it may be regarded as fixed. According to International Critical Tables, the mol-fraction composition of dry air is given by the first column of figures in Table 1. Molecular weights are given in the second column; the last figure in the third column is the apparent molecular weight of the mixture; the fourth ` column of figures gives the ordinary weight-fraction composition. It is well known that dry air contains other gases besides those listed in Table-1-; but these are present in such minute amounts .that they can be grouped together as argon. Values in the lower section of Table 1 give the approximate mol-fraction composition of what is called argon in the upper portion of the table. In physical and chemical thermodynamics, there is a distinct advan tage in using a different unit of weight, the mol, for each different sub stance involved. A mol of oxygen weighs 32.000' lb-as a matter of defi nition ; a mol of any other substance is a weight, in pounds, equal to its molecular weight. Specific Volume and Density The ratio of total volume to total weight is called specific volume, v. In the English system, volume is expressed in cubic feet and weight in pounds; hence, specific volume is expressed in cubic feet per pound. The reciprocal of specific volume, that is, weight per unit volume is called weight, density, d. The unit of density is the pound per cubic foot-. 1