Document kmoQnrmJRQJBxJ8gKNdrQvwd0

American Society of Heating and Ventilating Engineers Guide, 1932 Fig. 13. Combination of Recirculated and Outside Air (Case C) Chapter 31--Central Fan Systems in depth, warms the incoming air to approximately 35 F to prevent freezing any of the spray water. The air passing through the spray chamber is saturated and leaves at a temperature of h = 41 F. The heat to be supplied the heater is: Hi = 0.24 (Is -- 41) M Btu per hour The heat to be supplied the tempering coil is: Ht = 0.24 (35 -- ta)M Btu per hour The amount of heat, per pound of air circulated,-to be supplied the humidifying washer or humidifier is the difference between the heat content of the assumed dry air entering Fig. 14. Outside Air Circulated; Constant Relative Humidity in Room (Case D) Fig. .15. Combination of Recirculated and Outside Air; Constant Relative Humidity in Room (Case E) 448 Fig. 16. Outside Air Circulated; Constant Temperature and Rela tive Humidity Maintained in Each Room (Case F) the washer at a temperature of hr = 35 F and the leaving saturated air at 15.7 -- 8.4 = 7.3 Btu per pound of dry air The amount of heat required for the washer is: Ht = 7.3 M Btu per hour The total amount of heat required by the apparatus'is therefore; Hi -f Hi + Hi Btu per hour = 41 F, or If a washer having a humidifying efficiency of 67 per cent without water heater is em ployed it will be necessary to heat the outside air drawn into the apparatus by means of a tempering coil to such a temperature that the air in passing through the water sprays will become partially saturated (adiabatically) having a moisture content per pound of air equal to saturated air at 41 F. If the incoming air is warmed by the tem pering coil to tv = 88 F (requiring a two-section-depth heater) it will be cooled in the washer to 64 F or 88 -- 64 = 24 deg. If the humidifying efficiency of the washer were 100 per cent, the air would become adiabatically saturated at 52 F or a temperature drop of 88 -- 52 = 30 F. The efficiency of the washer is, however, only 67 per cent, so that the actual temperature drop will be 0.67 X 36 deg or 24 deg, as used. The heat to be supplied the heater is in this case Hi -- 0.24 (lj -- 64) M Btu per hour, and for the tempering coil is Ht = 0.24 (88 -- t0)M. The total heat required by the apparatus is5i + Ht, no heat being supplied to the washer. Case E. (Fig. 15) The arrangement of the heating and ventilating apparatus is similar 449