Document JNqGM86LOeaw2jwzxmB0XEowK

440 CHAPTER 19 1950 Guide Table 10. Pressure Drop in Duct Inches of Water per 100 Feet of Dtict Length Eqdiya- LBHT Length or Duct (Ft) 0.04 0.05 0.06 Total Pressure Drop in Duct (In. o^Watbh) 0.07 0.08 0.09 o.io 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 85-44 45-64 55-64 66-74 0.10 0.13 0.15 0.18 0.20 0.23 0.25 0.28 0.30 0.33 0.35 0.38 0.40 0.43 0.45 0.48 0.50 0.08 o.m 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 0.32 0.34 0.36 0.38 0.40 0.07 0.08 0.10 0.12 0.13 0.15 0.17 0.18 0.20 0.22 0.23 0.25 0.27 0.28 0.30 0.32 0.33 0.06 0.07 0.09 0.10 0.11 0.13 0.14 0.16 0.17 0.19 0.20 0.21 0.23 0.24 0.26 0.28 0.29 75-84 85-84 95-104 105-114 0.05 0,06 0.08 0.09 0.10 0.11 0.13 0.14 0.15 0.16 0.18 0.19 0.20 0.21 0.23 0.24 0.25 0.05 0.06 0.07 0.08 0,09 0.10 0.11 0.12 0.13 0.14 0.16 0.17 0.18 0.19 0.20 0.21 0.22 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.04 0.05 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.15 0.16 0.17 0.18 .115-129 180-149 150-169 .170-189 0,03 0.04 0.05 0.06 0 07 0.08 0.08 0.09 0.10 0.11 0.12 0.12 0.13 0.14 0.15 0.16 0.17 0.03 0.04 0.04 0.05 0.06 0.07 0.07 0.08 0.09 0.09 0.10 0.11 0.11 0.12 0.13 0.14 0.14 0.03 0.03 0.04 0.04 0.05 0.06 0.06 0.07 0.08 0.08 0.09 0.09 0.10 0.11 0.11 0.12 0.13 0.02 0.03 0.03 0.04 0.04 0.05 0.06 0.06 0.07 0.0? 0.08 0.08 0.09 0.09 0.10 0.11 0.11 190-214215-239 240-264 265-289 290-324 325-374 375-424 425-474 002 0.03 0.03 0.04 0.04 0.05 0.05 -0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.10 0.02 0.03 0.03 0.03 0.04 0 04 0.05 O.OS 0.05 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.09 0.02 0.02 0.02 0.03 0.03 0.04 0.04 0.04 0.05 0.05 0.06 0.06 0.06 0.07 0.07 0.08 0.08 0.01 0.02 0.02 0.03 0.03 0.03 0.04 0.04 0.04 0.05 0.05 0.05 0.06 0.06 0.07 0.07 0.07 0.01 0.02 0.02 0 03 0.03 0.03 0.03 0.04 0.04 0.04 0.05 0.05 0.05 0.06 0.06 0.06 0.07 0.01 0.02 0.02 0.02 0.03 0.03 0:03 0.03 0.03 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.06 0.01 0.01 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04 0.05 0.05 0.05 0.01 0.01 0.01 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04 0.05 475-624 625-674 576-625 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0:03 0.03 0.03 EqxjxtaLENT Total Pressure Drop in Duct (In. or Water) Duct (Ft) 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.32 0.34 0.36 0.38 0.40 0.45 0.50 35-44 45-54 55-64 65-74 75-84 85-94 85-104 105-114 115-129 130-149 150-169 170-189 190-214 216-239 . 240-264 265-289 290-324 325-374 375-424 425-474 475-624 . 625-674 676-625 0.53 0.55 0.58 0.60 0.63 0.65 0.68 0.70 0.73 0.75 0.80 0.85 0.90 0.95 1.00 1.13 1.25 0.42 0.44 0.46 0.48 0.50 0.53 0.64 0.56 0.56 0.60 0.64 0.68 0.72 0.76 0.8C 0.90 1.00 0.35 0.87 0.39 0.40 0.42 0.48 0.45 0.47 0.46 0.60 0.53 0.57 0.66 0.64 0.67 0.76 0.83 0.30 0.32 0.33 0.34 0.36 0.37 0.39 0.40 0.42 0.43 0.46 0.49 0.52 0.54 0.57 0.64 0.72 0.26 0.28 0,29 0,30 0.31 0.33 0.34 0.35 0.36 0.38 0.40 0.43 0.45 0.48 0.50 0.56 0.63 0.23 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.32 0.33 0.36 0.38 0.46 0.42 0.45 0.56 0.56 0.21 0.22 0.23 0,24 0.25 0.26 0.27 0.28 0.29 0.3(1 0.32 0,33 0.36 0.38 0.46 0.45 0.60 0.19 0.20 0.21 0.22 0.23 0.24 0.25 0:26 0.27 0.28 0.29 0.31 0.33 0.35 0.37 0.41 0.46 0.18 0.18 0.19 0.20 0.21 0.22 0.23 0.23 0.24 0.25 0.27 0.28 0.30 0.32 0.33 0.38 0.47 0.16 0.16 ,0.16 0.17 0. IS 0.19 0.19 0.2(] 0.21 0.21 0.23 0.24 0.26 0.27 0.29 0.32 0.36 0.1J 0.14 0.14 0.15 0.16 0.16 0.17 0.18 0.16 0.19 0.2(1 0.21 0.23 0.24 0.25 0.26 0.31 0.12 0.12 0.13 0.13 0.14 0.15 ,0.15 0.16 0.16 0.1V 0.18 0.19 0.20 0.21 0.22 0.25 0.28 0.11 0.11 0.12 0.12 0.13 0.13 0.14 0.14 0.15 0.15 0.16 0.17 0.18 0.19 0.20 .0.23 0.25 0.1* 0.H O.lf 0.11 0.11 0.11 0.11 0.13 0.13 DM 0.14 0.15 0.1b 0.11 0.1? 0.2C 0.22 0.0? O.tt 0.0J 0.1( 0.1( 0.1( 0.11 0.11 0.12 0.12 o.ia 0.14 0.1! 0.15 0.1? 0.1? 0.20 0.08 0.08 0.08 0.09 0.09 0.10 0.10 0.10 0.11 0.11 0.12 0.12 0.13 0.14 0.15 .0.16 0.18 0.07 0.07 0.08 0.08 0.08 0.09 0.09 0.09 0.10 0.10 0.11 0.11 0.12 0.13 0.13 0.15 0.17 0.0( 0,01 o.m o.m o.m 0.0? o.m o.m o.m o.m 0.1K 0.IC 0.K 0.11 0.11 0.13 0.14 0.05 0.0< 0.(X 0.06 0.0( o.m o.m o.m 0.0? 0.0? 0.0? o.m o.m o.m 0.1C 0.11 0.13 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.11 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.10 o.a 0.04 0.04 0.04 0.05 0.05 0.05 0.0! 0.05 u.<x 0.06 o.m o.m o.m o.o: 0.0? 0.09 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.07 0.08 0.08 Coils of copper finned tubing through which cold water is pumped are available for cooling. They require less space than air washers and have; the advantage that no moisture-is added to the air when the temperature j of the water rises above the dew-point. Ample coil surface find fan capacity j are necessary with this type of cooling. It is thoroughly feasible to use ice or mechanical refrigeration in connec- I tiori with a warm air system and to cool the building by this method, pro- \ Mechanical Warm Air Systems 441 vided the building is reasonably well constructed and insulated. Windows and doors.should be tight, and awnings should be supplied on the sunny side of the building. See also Chapters 29, 36 and 37. Conclusions drawn from studies6 conducted in the University of Illinois Research Residence, subject to the limitations of the test are: 1. An uninsulated building of ordinary residential type may require the equivalent of three tons of ice in 24 hr on days when the maximum outdoor temperature reaches 100 F if an effective temperature of approximately 72 deg is maintained indoors. 2. The use of awnings at all windows in east, south, and west exposures may result in savings of from 20 to 30 per cent in the required cooling load. 3. The cooling load per degree difference in temperature is not constant but in creases as the outdoor temperature increases. 4. The heat lag of the building complicates the estimation of the cooling load under any specified conditions and makes such estimates, based on the usual methods of computation, of doubtful value. 5. The seasonal cooling requirements are extremely variable from year to year, and the ratio between the degree-hours of any two seasons occurring within.a 10-year period may be as high as 7.5 to 1. Hence, an average value of the degree-hours cool ing per season is comparatively meaningless. 6. The duct system in a forced-air heating installation can be successfully con verted to a system for conveying cool air for the purpose of cooling the structure. No condensation of moisture was observed when the duct temperatures were not less than 65 F. 7. Cooling by means of water at a temperature of 60 F is not satisfactory unless an indoor temperature of.less than 80 F is maintained. 8. In the selection of cooling coils, the additional frictional resistance of the coil to flow of air must be given consideration. 9. Cooling the structure by introducing large quantities of outdoor air at night tended to reduce the amount of cooling required on the following day, and was a practical means of providing more comfortable conditions in those homes where cool ing systems were not available. DESIGN OF COOLING SYSTEM The general procedure which may be used for the design of a summer cooling system in a forced-air installation is: 1. Calculate heat gain for each room or space to be conditioned. (See Chapters 9 and 12). Allowance for addition of outside air must be included in this calculation. 2. Select a temperature of air leaving supply inlets. In University of Illinois Research Residence tests a value of from 65 to 70 F was found satisfactory. 3. Determine indoor conditions to be maintained. In Research Residence 80 F dry-bulb and 45 per cent relative humidity were found satisfactory. 4. Determine the quantity of air to be introduced into each room. 5. Estimate heat loss in duct system between cooling unit and supply registers. 6. Calculate the sensible and latent heat to be removed by the cooling unit. 7. Determine size of ducts in duct system and size of registers, as explained in this chapter. .8. Determine pressure loss in duct system and select fan having proper capacity. 9. Select cooling unit from manufacturer's data. Specify temperature and pres sure of available cooling water, voltage and characteristics of electrical supply, and method of control of apparatus. 10. Select cooling coils from manufacturer's data to take care of latent heat load and to give required drop in air temperature with the weight of air flowing. (See Chapter 35). 11. If system is to be used for both winter heating and summer cooling, duct sizes must be checked to insure that velocities and friction losses are reasonable for both conditions of operation. Adjustable dampers will be necessary to make changes in air distribution for the two seasons. Provision must also be made for changing fan speeds for summer and winter operation.