Fan Performance

Transcription

Fan Performance

Fan Performance
Mark Stevens
Deputy Executive Director
AMCA International
The International Authority on Air System Components
Fan Testing for Air Performance
AMCA Standard 210
Piezometer Ring
Fan Static Pressure
Nozzles
Fan Airflow
Test Fan
Auxiliary Fan
AMCA 210 Test Results
800
2.5
700
2
500
1.5
400
1
300
200
0.5
100
0
0
0
2
4
6
8
Air Flow, Q
10
12
Power, H
Pressure, P
600
AMCA Standards 500-D & -L
Test Damper
Piezometer Ring
Damper Pressure Drop
Nozzles
Damper Airflow
Auxiliary
Fan
AMCA
TestPoint
Results
Fan 500-D
Operating
700
600
500
Pressure, P
Operating Point
400
300
200
100
0
0
2
4
6
8
Air Flow, Q
10
12
Speed Change
800
700
600
New Operating Point
Pressure, P
500
New speed
Operating Point
400
300
200
100
0
0
2
4
6
Air Flow, Q
8
10
12
14
Damper Opening
700
600
Pressure, P
500
Operating Point
400
New Operating Point
300
New System
200
100
0
0
2
4
6
8
Air Flow, Q
10
12
System Effect
1ST Definition
Installed duct configuration does not match
tested duct configuration
Installation Type D
Ducted Inlet / Ducted Outlet
Piezometer Ring
Fan Static Pressure
Nozzles
Fan Airflow
Test Fan
Auxiliary Fan
Plenum
Plenum
Installed Fan
AMCA Catalog Ratings
• “Performance certified is for
installation type:
◦
◦
◦
◦
A: Free inlet, Free outlet”
B: Free inlet, Ducted outlet”
C: Ducted inlet, Free outlet”
D: Ducted inlet, Ducted outlet”
System Effect
2nd Definition
Even when the tested duct configuration matches
the installed duct configuration, improper duct
design can introduce adverse flow conditions
Elbow Example
AMCA Publication 201
Detailed Plenum Example
Plenum
E-F
duct friction at 5000CMH (Q)
E
contraction loss-plenum to duct
E
PS energy required to create velocity at E
D
PV loss (also PT loss) at D as result of air velocity decrease
747 Pa (duct design)
50 Pa (part of duct system)
0 Pa
PS does not change from duct to plenum at D
C-D outlet duct on fan as tested
0 Pa
--------------------
REQUIRED Fan PS
922 Pa
D-E duct friction at 5000CMH (Q)
D
contraction loss-plenum to duct
D
PS energy required to create velocity at D
B-C SEF
149 Pa
B-C PV loss (also PT loss) at C as result of air velocity decrease
0 Pa
PS does not change from duct to plenum at C
------------------
REQUIRED Fan PS
1071 Pa
Fan Laws for Speed Change
QC =
( )
( )
( )
NC
N
Q
Q, Fan Airflow Rate
P
P, Fan Pressure
H
H, Fan Power
2
PC =
NC
N
3
HC =
NC
N
8% Speed Change
800
2.5
700
2
600
500
1.5
400
1
300
200
0.5
8% More Q
100
0
0
0
2
4
6
8
Air Flow, Q
10
12
14
Power, H
Pressure, P
25% More H
Plenum Example from AMCA 201
Assuming:
• Use of the same fan for both systems
• Can attain both operating points with a
change in speed
• The increased in power consumption to
overcome System Effect is about 25%
◦ (1071/922)0.5 = 1.08 (Fan Law for pressure)
◦ 1.083 = 1.25 (Fan Law for Power)
Ducted Fan
Fan as Tested
C-D duct friction
A
free inlet
B-C outlet with straight duct attached for 2 or more diam.
0 Pa (no SEF)
0 Pa (no SEF)
--------------------
REQUIRED Fan PS
750 Pa
Ducted Fan
Exhaust System
A
A-B
B
C
E
Entrance loss-sharp edge duct
Duct friction at 5000CMH
SEF 1 (Elbow at Inlet)
SEF 2 (Obstruction)
SEF 3 (Abrupt Discharge)
REQUIRED Fan Ps
150 Pa
50 Pa
150 Pa
------------------
1200 Pa
Inlet System Effect
SYSTEM EFFECT
DESIGN RESISTANCE
ACTUAL FAN CURVE WITH
SYSTEM EFFECT
CATALOG PERFORMANCE
CURVE
AIRFLOW DEFICIENCY
DESIGN AIRFLOW
Outlet System Effect
ACTUAL SYSTEM WITH
SYSTEM EFFECT
CALCULATED SYSTEM WITH
NO ALLOWANCE FOR
SYSTEM EFFECT
SYSTEM EFFECT LOSS AT
DESIGN AIRFLOW
DESIGN RESISTANCE
CATALOG PERFORMANCE
CURVE
AIRFLOW DEFICIENCY
DESIGN AIRFLOW
Speed Changes
• Before Increasing Speed
◦ Check with the manufacturer for max safe
operating speed
◦ Determine expected power increase
• Motor size
• Electric Service
◦ Expect more noise
Rules of Thumb
• Minimum 2.5 duct diameters on Outlet
• Minimum 3 to 5 duct diameters on Inlet
• Avoid inlet swirl
Recommendations
• Allow enough space in the building design
to allow for appropriate fan connections to
the system
Recommendations
• Use allowances in the design calculations
when space or other factors dictate less
than optimum arrangement of the fan
outlet and inlet connections
Recommendations
• Include adequate allowance for the effect
of all accessories and appurtenances on
the performance of the system and the fan
Thank you
AMCA International, Inc.
30 W. University Drive
Arlington Heights, IL 60004
USA
Tel: +1 847 394 0150 Fax: +1 847 253 0088
www.amca.org
Mark Stevens - [email protected]

Fan Performance

Transcription

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