Chapter 20 : Ducts 697damper resistance necessary to give the required flow when the static pressure in the main duct beforeoff-take is 10 mm of water.If the branch pieces are placed 12 m apart along the main duct, calculate the required percentage staticregain in the main duct across the off take shown in order that the static pressure in the next off takewill be 10 mm of water also. The dynamic loss coefficient for the branch, 90° bend and exit grill maybe taken as 0.65, 0.3 and 0.8 respectively.(Ans. 9.94 mm of water; 66.2%)9. An air duct system is provided as shown in Fig. 20.29. The standard air enters at point A with a staticpressure of 12 mm of water.30 m15 m15 m.30 m60 m22.5 mFig. 20.29The branch BE delivers 60 m/min at E, branch CF delivers 180 m'Imin at F and the main ductdelivers 240 m'/min at D.Using equal pressure drop method, find the duct dimensions. Assume free exit at each outlet.[Ans. Dan = 1 m; Duc = 0.9 m: Den = 0.75 m; Dag = 0.375 m; De =0.55 m]10. An air conditioning duct runs straight from fan over 60 m length. It has four equally spaced outletdiffusers mounted on duct, the last one being at the end of duct. The volume flow rate through eachdiffuser is 1 m'/s. The velocity at duct inlet is 15 m/s. Carry out the duct design by static regainmethod if static regain factor is 0.75 at each transition and frictional pressure drop is given byP 0.002 268 (Q)y.852(D)4973mm of waterVP, =andmm of water4.04where Q is in m'/s and V is in m /s.[Ans. D, = 0.583 m ; V = 9.15 m/ s, D, = 0.646 m: V, = 5.82 m /s, D, = 0.661 m;V = 3.6 m/ s, D. -0.595 m ][Hint : Solve this question by using the procedure given in Example 20.10]

Given-Data:- l=60m3Volume=1m3Velocity = 15m/sRegainFactor=0.75 To-Find:- Diameters and Velocities at…

An air conditioning duct runs straight from fan over 60 m length. It has four equally spaced outlet diffusers mounted on duct, the last one being at the end of duct. The volume flow rate through each diffuser is 1 m'/s. The velocity at duct inlet is 15 m/s. Carry out the duct design by static regain method if static regain factor is 0.75 at each transition and frictional pressure drop is given by Pr 0.002 268 (0).852 mm of water (D) 4973 M mm of water and P,= where Q is in m/s and Vis in m /s. [Ans. D, = 0.583 m : V = 9.15 m/ s, D, = 0.646 m : V, = 5.82 m /s, D, = 0.661 m: V = 3.6 m/ s, D, = 0.595 m )

An air conditioning duct runs straight from fan over 60 m length. It has four equally spaced outlet diffusers mounted on duct, the last one being at the end of duct. The volume flow rate through each diffuser is 1 m'/s. The velocity at duct inlet is 15 m/s. Carry out the duct design by static regain method if static regain factor is 0.75 at each transition and frictional pressure drop is given by Pr 0.002 268 (0).852 mm of water (D) 4973 M mm of water and P,= where Q is in m/s and Vis in m /s. [Ans. D, = 0.583 m : V = 9.15 m/ s, D, = 0.646 m : V, = 5.82 m /s, D, = 0.661 m: V = 3.6 m/ s, D, = 0.595 m )

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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