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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![Chapter 20 : Ducts 697
damper resistance necessary to give the required flow when the static pressure in the main duct before
off-take is 10 mm of water.
If the branch pieces are placed 12 m apart along the main duct, calculate the required percentage static
regain in the main duct across the off take shown in order that the static pressure in the next off take
will be 10 mm of water also. The dynamic loss coefficient for the branch, 90° bend and exit grill may
be 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 static
pressure of 12 mm of water.
30 m
15 m
15 m.
30 m
60 m
22.5 m
Fig. 20.29
The branch BE delivers 60 m/min at E, branch CF delivers 180 m'Imin at F and the main duct
delivers 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 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
P 0.002 268 (Q)y.852
(D)4973
mm of water
V
P, =
and
mm of water
4.04
where 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]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9184cb98-6a71-4eba-a6c9-8880d9027f22%2Fda160edb-cb5f-48b1-8c80-a9e0fadc00db%2Faje3kai_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Chapter 20 : Ducts 697
damper resistance necessary to give the required flow when the static pressure in the main duct before
off-take is 10 mm of water.
If the branch pieces are placed 12 m apart along the main duct, calculate the required percentage static
regain in the main duct across the off take shown in order that the static pressure in the next off take
will be 10 mm of water also. The dynamic loss coefficient for the branch, 90° bend and exit grill may
be 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 static
pressure of 12 mm of water.
30 m
15 m
15 m.
30 m
60 m
22.5 m
Fig. 20.29
The branch BE delivers 60 m/min at E, branch CF delivers 180 m'Imin at F and the main duct
delivers 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 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
P 0.002 268 (Q)y.852
(D)4973
mm of water
V
P, =
and
mm of water
4.04
where 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]
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