Document 15YGe4J0x9jK5zb1v6xek00xd

314 CHAPTER 12 1951 Guide (Refer to Chapter 35 for coil selection and efficiency.) From note under Equation 19 the dry-bulb range will be (80--54.6) X 0.85 = 21.6 deg, and the dry-bulb temperature of air leaving the coil will be 80 -- 21.6 = 58.4 F. The dry-bulb temperature leaving the fan (including the heat supplied by the fan motor), or delivered into the room, will be (from Equation 21): 184,415 - 19,100 U 80 - 1.08 X 7900 80 - 19.4 60.6 F. With good distribution and diffusion, this temperature should not produce objec tionable drafts. Example 18: Summary Outdoor Conditions................... 95 DB Space Conditions........................ 80 DB 78 WB 65 WB 0.0169 Humidity Ratio 0.0098 Humidity Ratio Difference......................... 15 . 0.0071 Sensible Load Transmission Bta/Hr Roof 4000 sq ft X 53 X 0.34 =............................................................ 72,000 S. Wall 405 sq ft X 6 X 0.41 =....... 995 E. Wall 765 sq ft X 11 X 0.52 =........... 4,380 N. Wall Ex. 170 sq ft X 3 X 0.52 =.......................... .................... 265 N. & W. Party Wall 1065 sq ft X 2 X 0.26 =.... .......................... 550 Floor Hone Door 35 sq ft X 15 X 0.59 =................................... ............................. 310 All Glass and Rest of Doors =..........'.................................................... 3,020 Solar Radiation S. Glass 60 sq ft X 14 =.............................................................. S. Glass (Doors) 35 sq ft X 42 --.......................................................... E. Glass (Doors) 18 sq ft X 14 =........................................................ N. Glass 30 sq ft X 15 =................................. 840 1,470 250' 450 Internal Load Infiltration 67 cfm X 1.08 X 15" =..................................................... 1,085 Lights (12,000 X 1-20 + 4000) 3.41 =................................................... 62,700 People 85 X 200 =.................................................................................... 17,000 Motor, Fan 75hp X 2544 =................................................................. 19,100 Total Sensible Space Load.......................................................... 184, 415 Latent Load Infiltration 67 cfm X 4840 X 0.0071 ................................ ............... 2,300 People 85 X 250 =............................................................. :................ . 21,250 Total Latent Space Load:......................................................................... 23,550 Ventilation Air Sensible 1275 cfm X 1.08 X 15 =.............. ...................................................... Latent 1275 cfm X 4840 X 0.0071 =....... .................... .................. ............ . 20,700 43,800 Grand Total Load. 272,465 LETTER SYMBOLS USED IN CHAPTER 12 a = fraction of incident solar radiation absorbed, dimensionless; subscripts D, d, t refer to direct, diffuse and total, respectively. . /3 = solar altitude, degrees. y = wall solar'azimuth, degrees. c -- emissivity, dimensionless. -. 9 = incident angle, degrees. X = amplitude decrement factor, dimensionless. a = permeability to moisture transmission, grains per (square foot) (hour) (inch mercury). Cooling Load 315 = fraction of incident solar radiation transmitted, dimensionless. T = Subscripts D, d, t refer to direct, diffuse and total, respectively. $ = solar azimuth, degrees. j, = wall azimuth, degrees. A = area across which heat is being transferred, square feet. , _ unit surface conductance, Btu per (hour) (square foot) (Fahrenheit degree). 1 Subscripts c, r, o, and i refer to convection, radiation, outdoor, and indoor, respectively. (J, = fraction of total window area receiving direct solar radiation when shaded by window reveal, dimensionless. h = enthalpy of air per pound of dry air, Btu per pound. Subscripts i, o, and s refer to indoor, outdoor, and supply air, respectively, I = incident solar radiation, Btu per (hour) (square foot). Subscripts D, d, Dn, and t refer to direct, diffuse, direct normal and total solar radiation, respectively. K = cosine of angle of incidence for direct solar radiation striking a surface, dimen sionless. k = thermal conductivity of building material, Btu per (square foot) (hour) (Fahrenheit degree per inch). L = thickness of building material, inches. { = height of window, feet. Q = rate of entry of outdoor air, cubic feet per minute. q ^ __ required air quantity through conditioning equipment, cubic feet per minute. q = instantaneous rate of heat transfer, Btu per hour. q, = instantaneous latent heat load, Btu per hour. qa --- latent heat load due to moisture transmission through materials, Btu per (hr) (Bq ft). q, = instantaneous sensible heat load, Btu per hour. q, = q. + q., Btu per hour. R, = low temperature radiant energy received from outdoor surroundings (does not include solar radiation), Btu per (hr)(sq ft of receiving surface). R = radiant energy emitted by a black body, Btu per (hr) (sq ft). Subscripts go and L refer to outdoor surfaces of glass and building, respec tively. S = rate of heat storage within a glass section, Btu per (hr)(sq ft). L = sol-air temperature, Fahrenheit degrees. (,* = sol-air temperature at a time earlier than the time for which heat gain is being found by an amount that is equal to the time lag of the wall or roof, Fahren heit degrees. I,i = temperature of indoor glass surface, Fahrenheit degrees. t,,, = temperature of outdoor glass surface, Fahrenheit degrees. (i = indoor air temperature, Fahrenheit degrees. to = temperature of outer surface of building, Fahrenheit degrees. tm = 24-hr cyclic average sol-air temperature, Fahrenheit degrees. to = outdoor air temperature, Fahrenheit degrees. tp = tm + (L* -- (m), net equivalent outdoor temperature for combined periodic and mean heat flow, Fahrenheit degrees. t, = room supply air dry-bulb temperature, Fahrenheit degrees. U = overall coefficient of heat transfer of a structural seotion, Btu per (square foot) (hour) (Fahrenheit degree). r. = volume of outdoor air per pound of dry air, cubic feet. w = width of window, feet. IF = humidity ratio, pounds moisture per pound of dry air. Subscripts i, o, and s refer to indoor, outdoor, and supply air, respectively.