Document xg76R8JkjYOkzBBMQv2MaQnE

Heating Ventilating Air Conditioning Guide 1938 to maintain these conditions, and (6) the temperature rise of the solution in passing through the absorber. a. The heat content of the entering air: From Table 6, Chapter 1, weight of vapor at 70 F dew-point is 0.01574 lb times heat content of steam at 100 F. dry-bulb is 1104.2 (Table 8, Chapter 1) equals 17.41 Btu per pound plus heat content of dry air at 100 F is 24.0 (Table 6, Chapter 1) resulting in heat content of mixture as 41.41 Btu per pound. Similarly, the heat content of the leaving air: Weight of vapor at 35 F dew-point is .0.004262 X 1097.5 = 4.68 Btu per pound plus heat content of dry air at 85 F is 20.39 resulting in heat content,of mixture as 25.07 Btu per pound. Heat to be extracted from air is 1000 X (41.41 . 25.07) =-16,340 Btu per minute. Add to this the heat of mixing of-18if lithium chloride at 80 F equals 145 -- (0.186 X 80) = 130 Btu per pound (Table 10) or for 1000 lb of air X, (0.01574 - 0.00426) X 130 = .1494 Btu per minute. Heat to be removed from solution is. 16,340 + 1494 = 17,834 Btu per minute. b. The weight of solution circulated is 200 X 1.275 (Table 8) X 8.33 = 2124 lb per minute. Its heat capacity is 2124 X 0.631 (Table 10) = 1340 Btu per minute per degree Fahrenheit. The temperature rise is 17,834 -s- 1340 = 13.31 F. -j 3 ) I i ; { } ? ^ Chapter 3 PHYSICAL AND PHYSIOLOGICAL PRINCIPLES OF AIR CONDITIONING ' - - Vitiation of Air, Heat Regulation in Man, Effects of Heat, Effects of Cold and Temperature Changes, Acclimatization, Effective Temperature Index of Warmth, Optimum Air Condi- tions. Winter, and Summer Comfort Zone, Optimum Huxnid- ity. Air Quality and Quantity, Air Movement and Distribution, Natural and Mechanical Ventilation, Heat and Moisture ! Losses, Ultra-Violet Radiation and Ionization, Recirculation and Ozone, Ventilation Standards VENTILATION is defined in part as "the process of supplying or removing air by natural or mechanical means to or from any space." (See Chapter 45.) The word in itself implies quantity but not necessarily ; quality. From the standpoint of comfort and health, however, the problem is now considered to be one of securing air of the proper quality ^ rather than of supplying a given quantity. The term air conditioning in its broadest sense implies control of any or all of the physical or chemical qualities of the air. More particularly, it includes the simultaneous control of temperature, humidity, movement, and purity of the air. The term is broad enough to embrace whatever ; other additional factors may be found desirable for maintaining the \ atmosphere of occupied spaces at a condition best suited to the physio| logical requirements of the human body. j VITIATION OF AIR I Under the artificial conditions of indoor life, the air undergoes certain \ 1 physical and chemical changes which are brought about by the occupants themselves. The oxygen content is somewhat reduced, and the carbon dioxide slightly increased by the respiratory processes. Organic matter, which is usually perceived as odors, comes from the nose, mouth, skin and clothing. The temperature of the air is increased by the metabolic processes, and the humidity raised by the moisture emitted from the skin and lungs. There is also a marked decrease in both positive and negative ions in the air of occupied rooms but the significance of this factor is still questionable1. Contrary to old theories, the usual changes in oxygen and carbon dioxide are of no physiological concern because they are much too small even under the worst conditions. The amount of carbon dioxide in air is Changes in Ionic Content in Occupied Rooms Ventilated, by Natural and Mechanical ^Methods, by C. P. Yaglou, L. C. Benjamin and S. P. Choate (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 191). x50 51