Document DMdba3vDo6rMZJ13jLpvk1rQa

American Society of Heating ami Ventilating Engineers Guide, 1930 905 grains per hour. 1,000 X 265 = 265,000 B.t.u. sensible heat; 1,000 X 134 = 134,TOO B.t.u. latent heat and 1,000 X 905 = 905,000 grains or 129 lb. of water vapor will be added per hour to the air in the auditorium. These sensible and latent heat loss additions may also be found as follows: The effective temperature of the condition 75 deg. dry bulb and 63.5 deg. wet bulb is 70.3 deg. effective temperature. From ,Fig. 6 find 403 B.t.u. as the total heat added to the air by a person for 70.3 deg. effective temperature. From Fig. 9 find the percentage of sensible and latent heat at 75 deg. dry bulb to be 66.5 per cent and 33.5 per cent. The sensible heat added to the air in the auditorium is 1,000 X 0.665 X 403 = 267,995 B.t.u. per hour. The latent heat added is 1,000 X 0.335 X 403 = 135,005 B.t.u. per hour. Solution--Problem 1-B: From Figs. 7 and 8, respectively, the sensible and latent heat losses per person for 85 deg. dry bulb are found to be 164 and 225 B.t.u. per hour. The water vapor added to atmosphere is 1,520 grains per hour. The audience will then add 164,000 B.t.u. sensible heat, 225,000 B.t.u. latent heat and 1,520,000 grains or 217 lb; of water vapor to the air in the auditorium per hour. Problem 2: Neglecting the gain or loss of heat to an auditorium by transmission or infiltration through the walls, windows and doors, how many cubic feet of outside air, Table . 2. Condition of Sensible Perspiration for Various Atmospheric Conditions *> Atmospheric Condition Degree op Perspiration a 95 PER CENT R. H. 20 PER CENT R. BL E. T. Forehead clammy.............................................. Body clammy..................................................... Body damp......................................................... Beads on forehead- -................................ Body wet..... ........... ...... ............... .................... Perspiration on forehead runs and drips. .... Perspiration runs down body............ .............. 73.0 73.0 79.0 80.0 84.5 88.0 88.5 D. B. 73.6 73.6 79.7 80!8 85.4 89.0 89.5 W. B. 72.4 72.4 78.4 79.4 84.0 87.6 88.1 E. T. 75.0 75.0 81.0 87.0 86.5 94.0 90.0 D. B. 87.0 87.0 97.5 109.4 108.5 125.2 116.0 W. B. 60.7 60.7 67.5 75.2 74.6 85.4 79.5 oForty per cent of subjects registered degree of perspiration equal to or greater than indicated. b" Thermal Exchanges between the HumaA Body and its Atmospheric Environment," by F. C. Houghten, W. W. Teague, W. E. Miller, W, P. Yant (American Journal Physiology, Vol. 88, No. 3, April, 1929; pp. 386-406). with 65 deg. dry bulb, 59 deg. wet bulb and 63.1/deg. effective-temperature must be added per hour to an auditorium containing 1,000 people in order that the inside shall not exceed 75 deg. dry and 65 deg. wet bulb, respectively? Solution--Problem 2: Figs. 7 and 8 give 265 B.t.u. sensible heat and 905 grains of moisture as the additions per person with 75 deg. dry bulb in the auditorium. There fore 265,000 B.tiu. of sensible heat and 905,000 grains of moisture will be added to the air in the auditorium per hour. Taking 0.24 as the specific heat of air, 2.4. B.t.u. per pound of air will be required to raise the dry-bulb temperature from 65 to 75 deg. and 265;0--00 = 110,400 lb. of air or 110,400 X 13.4 = 1,479,000 cu. ft. of air per hour will be required. This is equivalent 1 479 000 to nhn vcn = 24.7 cu. ft. per person per minute. J.,Uvv/ X w The moisture content of the inside air as taken from a psychrometric chart is 76 grains per pound of dry air and that of the outside condition is 65 grains so the increase in moisture content will be 11 grains per pound of dry air. --905'000 = 82,300 lb. of dry air or approximately 83,000 lb. of air at the specified condition will be required. This is equivalent to 83,000 X 13.4 = 1,112,000 cu. ft. of air per hour or *1 = 18.5 1,0UU X OU cu. ft. of air per minute per person. The higher volume of 24.7 cu. ft. per person per minute will be required to keep the 96 Chapter 3--Standards of Ventilation dry-bulb from rising above the 75 deg. specified. The wet-bulb will, therefore, not rise to the maximum of 65 deg. Examples 1-A and 1-B demonstrate that while the effective tempera ture, and, hence, the feeling of warmth and rate of total heat loss, does not differ greatly in the two cases, the relative-proportion of sensible and latent heat loss is.reversed. In order to maintain the air conditions stipulated the air conditioning equipment must remove 61.6 per cent 97 -i