Determine the equivalent rectangular shaped duct sizes for the duct lay-out as shown below using equal friction method. The height of the duct should not exceed 30"and also the maximum velocity in the ducts adjacent to the plenum (BD) should not exceed 900 fpm. Assume that the pressure drop across each outlet diffuser to be 0.03" of wg and that for the (filter + heating + cooling coils) to be 0.34 " wg. Assume head loss in open dampers, transitions are negligible and equivalent length of elbow fitting 15'; equivalent length of Tee in main flow = 12'; equivalent length of Tee in branch flow 40'. Assume the length of the main trunk from point "B" to point "D" is 40' А Е 70 60 15 20 I5000 cfm 20 15 3000 cfm 2000 cfm 20 М В 2250 cfm F HC СС 401 15 fan 10 20 10 40" н 30 2000 cfm L 70 20 20" 1250 cfm 7000 cfm 1500 cfm С I 50 10 F-filter HC- heating coil; CC-cooling coil (b) Determine the size of the fan to be employed for the duct system and also determine the speed, shaft power and the total head developed by the fan (c) Show where you would install the dampers in order to balance the duct system
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