fan & system
TRANSCRIPT
1
Contents
1. Fan Type2. Fan Type Selection3. Fan Selection4. Fan Efficiency5. Fan & Air System6. Fan Operating Range7. AMCA 8. Fan Testing9. Deficient Performance 10. System Effect11. System Effect Movies12. System Effect Factor13. Outlet System Effect Factor14. Inlet System Effect Factor 15. Example
Axial Mixed Flow Centrifugal
Fan Type
2
Fan Type Selection
Specific Speed, ns is used to reflect the
characteristic of fans, or blowers. It differentiates the fan.
types and relates the major performance parameters
of a fan such as airflow qv, total pressure ptf and fan speed.
Specific speed is primarily used in three areas:
1. To determine fan type
2. For fan Classification
3. To perform design on geometrically similar blowers or
fans.
Specific Speed
n = Fan speed (rpm)
Q = Airflow rate (m³/s)
Pt = Total pressure (Pa)75.0
5.0
)(54.5
ts P
Qnn
� Specific speed of fan refers to single inlet fan operating individually.
� Evaluated at the point of maximum efficiency.
�When the design parameters are defined,
the specific speed can
be calculated. From the
magnitude of the
specific speed, the type
of blower to be used can be determined.
Specific Speed Fan Type
ns < 10 Radial Blade
ns = 15 ~ 65 Forward Curve
ns = 20 ~ 90 Backward Inclined
ns = 40 ~ 95 Mixed-Flow
ns = 50 ~ 150 Vane axial
ns = 70 ~ 250 Tube axial
ns = 100 ~ 400 Propeller
Fan Type Selection
Example!
A fan, under normal operating conditions, delivers 1.2m³/s
At a total pressure of 700Pa when running at a speed
n=1040rpm. Select the type of fan suitable for this .
application.
75.0
5.0
)(54.5
ts P
Qnn
75.0
5.0
)700(
)2.1(104054.5
46
Hence, the required fan can be forward curve, backward inclined or mixed flow fan.
Fan Type Selection
3
0 10 20 30 40 50 60 70 80 90 100 150 200 300 400
Radial Blade
Forward Curve
Backward Inclined
Mixed-Flow
Vane axial
Tube axial
Propeller
ns
Fan Type Selection
Fan Type SelectionAxial Vane Axial
Mixed Flow Axial
Centrifugal
Forward Curve
Centrifugal
Backward Curve
Centrifugal
Airfoil
Three Parameters to size a fan
� Air Volume (Q)
� Static Pressure (Ps) or Total Pressure (Pt)
� Air Velocity (V) or Velocity Pressure (Pv)
Fan Selection
4
A ABV = 10 m/s V = 20 m/s
kx
QxPkW
T
System A System B
FAN SYSTEM FAN SYSTEM
Q 12 m3/s 12 m3/s 12 m3/s 12 m3/s
Ps 800 Pa 800 Pa 800 Pa 800 Pa
Vel 10 m/s 20 m/s
Pv 59 Pa 237 Pa
PT 859 Pa Ps+Pv = 859 Pa 1037 Pa Ps+Pv = 1037 Pa
kW 12.52 kW 15.25 kW
Velocity Pressure [VP]
1. Fan Efficiency1. Fan Efficiency
1
Fan efficiency
5 � 10%
Fan efficiency �
Total efficiency (µT) = Q x PT (PV + PS)
1020 x kW
Static efficiency (µS) = Q x Ps .1020 x kW
A ABV = 10 m/s V = 20 m/s
kx
QxPkW
T
System A System B
FAN SYSTEM FAN SYSTEM
Q 12 m3/s 12 m3/s 12 m3/s 12 m3/s
Ps 800 Pa 800 Pa 800 Pa 800 Pa
Vel 10 m/s 20 m/s
Pv 59 Pa 237 Pa
PT 859 Pa Ps+Pv = 859 Pa 1037 Pa Ps+Pv = 1037 Pa
kW 12.52 kW 15.25 kW
Velocity Pressure [VP]
5
Velocity Pressure [VP] cont�d
Q = 12 m3/sPs = 800 Pa
System A PvA 59 Pa (10 m/s) System B PvB 237 Pa (20 m/s)
Total efficiency = Q x PT (PS + PV)
1020 x kW
µTA = 12 x 859 . µTB = 12 x 1037 .
1020 x 12.52 kW 1020 x 15.25 kW
= 80% = 80%
µSA = 12 x 800 . µSB = 12 x 800 .1020 x 12.52 kW 1020 x 15.52 kW
= 75% = 60%
Different in static efficiency with different power absorb
Velocity Pressure [VP] cont�d
Static EfficiencyQ = 12 m3/sPs = 800 Pa
System A PvA 59 Pa (10 m/s) System B PvB 237 Pa (20 m/s)
Static efficiency (µS) = Q x Ps .
1020 x kW
Fan set efficiency = fan µ x motor µ x (1 - transmission loss)
Belt driven → transmission loss 5-20% Direct driven coupling → transmission loss ≈ 0%
Motor efficiency High efficiency → premium high efficiency
2-10%
Fan Set Efficiency
6
Fan Set Efficiency (Belt Driven)
Motor Input Power = 100 kWMotor Efficiency = 90%Transmission Loss Thru Belt = 15%Fan Total Efficiency = 70%
Belt Driven:Fan set efficiency = 100 kW x 0.9 (90% motor µ)
x 0.85 (1 - 15% transmission loss = 85% transmission µ)
x 0.7 (70% fan µ)
= 53 kW (53%)
Fan Set Efficiency (Direct Driven)
Motor Input Power = 100 KwMotor Efficiency = 90%Direct Driven with Direct Shaft = 0%Fan Total Efficiency = 70%
Direct Driven:Fan set efficiency = 100kW x 0.9 (90% motor µ)
x 0.7 (70% fan µ)
= 63 kW (63%)
Fan Set Efficiency
Belt Driven
Transmission µ 85%
Fan output 53 kW
Fan shaft power 76 kW (1 - 15% transmission loss)
Power input 100 kW
Output 90 kW (90% motor µ)
7
Direct Driven (Coupling), Transmission Loss 0%
Fan output 63kW (70% µ)
Power loss thru coupling,0%
Power input 100 kW
Output 90 kW (90% motor µ)
Fan shaft power90 Kw
Fan Set Efficiency
Fan Set Efficiency
Direct Driven (Direct Shaft)
Fan output 53 kW (70% µ)
Fan shaft power 76 kW(motor shaft)
Power input 85 (100)kW
Output 90% motor µ= 76 ( 90) kW shaft power
(No Transmission Loss for direct shaft drive)
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
� An air system consist of a fan, ductwork, air control dampers, cooling coils, heating coil, filters, diffusers, noise attenuation, turning vanes, etc.
� The fan is the component in the system provides energy to the air system to overcome the resistance to flow of the other components.
8
Performance Fan Curve
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssu
re
700 RPM
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
Varying Fan Curve
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssu
re
750 RPM
700 RPM
650 RPM
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
System Resistance Curve
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 5 10 15 20 25 30 35 40 45
CFM x 100
Pre
ssu
re
B
A
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
9
Varying System Resistance Curve
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssu
re
Curve B
Curve A
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
Operating Point
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssu
re
Fan PerformanceCurve
System ResistanceCurve
Operating Point
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
Varying Operating Points
0
0.5
1
1.5
2
2.5
3
3.5
0 5 10 15 20 25 30 35 40 45
CFM x 100
Pre
ssu
re
700 RPM
1400 RPM
Operating Pointat 1400 RPM
Operating Pointat 700 RPM
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
10
Varying Operating Points - continued
0
0.5
1
1.5
2
2.5
3
3.5
0 5 10 15 20 25 30 35 40 45
CFM x 100
Pre
ssu
re
Operating Pointon Curve B
Curve B
Curve A
Operating Pointon Curve A
Fan and Air SystemFan and Air SystemFan and Air SystemFan and Air System
� Backward Curved Fan
Flow Rate, Q
Pre
ss
ure
, P
40%
85%Operating Range
Fan Operating RangeFan Operating RangeFan Operating RangeFan Operating Range
Unstable Operation in Fan & System
Fan Surge
(Backward Curve Fan)
Operating Range 40~85%
Fan Operating RangeFan Operating RangeFan Operating RangeFan Operating Range
11
� Forward Curved Fan
Flow rate, Q
Pre
ss
ure
, POperating
Range
30%
80%
Fan Operating RangeFan Operating RangeFan Operating RangeFan Operating Range
Unstable Operation in Fan & System
System Surge
(forward curve Fan)
Operating Range 30~80%
Fan Operating RangeFan Operating RangeFan Operating RangeFan Operating Range
� Axial Fan
Flow Rate, Q
Pre
ss
ure
, P
Operating Range
65%
95%
Fan Operating RangeFan Operating RangeFan Operating RangeFan Operating Range
12
Unstable Operation in Fan & System
Stalling (Axial or Mixed Flow Fan)
Operating Range 65~95%
Fan Operating RangeFan Operating RangeFan Operating RangeFan Operating Range
AMCA Licensed (Certified)on Air and Sound Performance
It is the prime responsibility of all manufacturers to publish true and accurate performance data to :-
� minimize risk and ensures performance of the system and of equipment design
� less engineering during the equipment development stage
� less queries from customers and consultant due to the third party (AMCA) certification
AMCA Licensed (Certified)on Fan Performance Curve
13
AMCA
Fan with AMCA Seal
Published Catalogue with AMCA Seal
WHEN EUROVENT TESTED THE PRODUCTS OF NON-PARTICIPATING
MANUFACTURERS MAJOR SHORTFALLS IN PERFORMANCE WERE REVEALED.
The Eurovent certification schemes have been operating for
almost six years now. In that time thousands of products have
been applied to the various programmes. When a product is
entered into a certification programme, Eurovent engineers
scrutinise the published data relating to the unit, and then select
individual units for third party testing. If a product achieves
performance claimed by the manufacturer, the range of product
from which it is derived is certified and included in the relevant
directory. However, the procedure does not end there, as
products are randomly selected for annual testing to ensure
performance is maintained. If a product fails to achieve the
claimed performance, that product together with all other
associated products is either de-rated or removed from the
market. In addition to testing products submitted for certification ,
Eurovent has recently been testing products from manufacturers
which are not part of Eurovent.
In a recent test of non-certified units readily
available in the European market, Eurovent
discovered that every single unit
manufactured by non-participating
companies failed to achieve its claimed
performance.
Concern
The procedures were exactly the same as those applied to
participating products, and involved the same analysis and testing by
third part laboratories. The fact that all products failed to live up to their
claims is, perhaps, remarkable, but what is of greater concern is the
fact that the shortfall in performance ranged from 12 to 29%.
�The shortfall in
performance ranged
from 12 to 29%.
Specifiers and end users buying these products at what appear to be
competitive prices are in fact being overcharged, as the products are
consistently failing to achieve their claimed performance. Taken over a
lifetime, the additional costs associated with under performance must
be quite considerable. Not only is the end user paying for something
that will not satisfy his requirements, but also there is the probability of
additional future expenditure to rectify the situation
Legislation
On a legal point, these units are clearly in defiance of the trades
description legislation as they patently do not do what they are claimed
to do.
WHAT�To have a reasonable accuracy the installed performance of a fan, we
must know
1) how the fan was tested and rated
2) what effect the system and its connections will have on
the fan�s performance.
Fan TestingFan TestingFan TestingFan Testing
14
There are four standard installation types as shown:
To simulate an inlet duct, an inlet bell and one equivalent duct diameter of inlet duct
are mounted on the fan inlet. The bell and duct is of the same size and shape as the
fan inlet boundary conditions.
To simulate an outlet duct, a uniform duct 2 to 3 equivalent diameter long of the fan
outlet area and a shape to fit the fan outlet.
Type C: Ducted inlet, Free outlet Type D: Ducted inlet, Ducted outlet
Type A: Free inlet, Free outlet Type B: Free inlet, Ducted outlet
Fan TestingFan TestingFan TestingFan Testing
Typical Commercial VentilationFree inlet, Free outlet (Type A)
Fan TestingFan TestingFan TestingFan Testing
Typical Commercial VentilationFree inlet, Ducted outlet (Type B)
Fan TestingFan TestingFan TestingFan Testing
15
Typical Commercial VentilationDucted inlet, Free outlet (Type C)
O ffice O ff ic e
Fan TestingFan TestingFan TestingFan Testing
Typical Commercial VentilationDucted inlet, Ducted outlet (Type D)
Fan TestingFan TestingFan TestingFan Testing
WHY�does a fan,which had been certified from laboratory
tests in accordance with AMCA Standard 210 and
bear AMCA Certify �Seal� of Air Performance,
sometimes fail to perform up to rating when it is
installed in the system
?
DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE
16
� Each setup in AMCA Standard 210 is a standardized arrangement
which is not intended to reproduce exactly any installation likely to
be found in the field.
� The infinite variety of possible arrangements of actual air systems
makes it impossible to duplicate these in the fan test laboratory.
AMCA Standard 210
DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE
DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE
Assuming the fan is rated and manufactured correctly, 3 most common causes of deficient performance of the fan/system combination are:
1. Improper outlet connections
2. Non-uniform inlet flow
3. Swirl at the fan inlet
� Use appropriate allowances in the design calculations when space or other factors dictate the use of less than optimum arrangement of the fan outlet and inlet connections.
� Design the connections between the fan and system to provide, as nearly as possible, uniform straight flow conditions at the fan outlet and inlet.
� Include adequate allowances for the effect of all accessories ad appurtenances on the performance of the system and fan.
� Use field measurement techniques which can be applied effectively on the particular system.
Precautions To Prevent Deficient Performance
DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE DEFICIENT PERFORMANCE
17
System Effects Defined:
�Anything you place in close proximity
before or after the fan that effects the
cataloged performance.
System EffectSystem EffectSystem EffectSystem Effect
Fan Outlet Velocity ProfilesBlast AreaCut off
25%
50%
75%
100% Effective Duct Length
OutletArea
DischargeDuct
Centrifugal Fan
Axial Fan
System EffectSystem EffectSystem EffectSystem Effect
Changing Velocity Profiles when using elbows
System EffectSystem EffectSystem EffectSystem Effect
18
Why System Effect is Important� Can decrease performance
� Can cause excess vibration
� Can cause excess noise
� Can require more energy (HP) to achieve rated performance
� Takes time to determine and understand
System EffectSystem EffectSystem EffectSystem Effect
Effective Duct Length = 2.5 Duct Diameters for 2,500 FPM or less
Add 1 duct diameter for each additional 1,000 FPM
For rectangular ducts, the equivalent duct diameter is
(4 x width x length / 3.14) ^ 0.5
Effective Duct Length
System EffectSystem EffectSystem EffectSystem Effect
click for MOVIE (Energy Efficient)
19
System Effect due to Fan Outlet RestrictionSystem Effect due to Fan Outlet RestrictionSystem Effect due to Fan Outlet RestrictionSystem Effect due to Fan Outlet Restriction
System Effect due to Poor Inlet Box DesignSystem Effect due to Poor Inlet Box DesignSystem Effect due to Poor Inlet Box DesignSystem Effect due to Poor Inlet Box Design
Summary of Fan Energy Summary of Fan Energy Efficient StrategyEfficient Strategy
Summary of Fan Energy Summary of Fan Energy Efficient StrategyEfficient Strategy
20
SYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTOR
� is a pressure loss which recognizes the effect of
fan inlet restrictions, fan outlet restrictions, or other
conditions influencing fan performance when installed
in the system.
System Effect CurveSystem Effect Curve
0.1
0.15
0.2
0.25
0.3
0.4
0.5
0.60.70.80.91.0
1.5
2.0
2.5
3.0
4.0
5.0
5 6 7 8 9 10 15 20 25 30 35 40 45
FGH IJ K L M N O
P
Q
R
S
T
U
V
W
X
AIR VELOCITY, FPM IN HUNDREDS(Air Density = 0.075 lbm/ft
3
)
1
2
3
SYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTOR
System Effect Curves for Outlet Ducts �Centrifugal FansSystem Effect Curves for Outlet Ducts �Centrifugal Fans
100% Effective Duct Length
Blast Area DischargeDuct
Outle tArea
Cutoff
t
Blast Area
NoDuct
12%Effective
Duct
25%Effective
Duct
50%Effective
Duc
100%Effective
Duct
U W --
System Effect Curve
U W --
U-V W-X --
W-X -- --
X -- --
-- -- --
0.4Outlet Area
0.5
0.6
0.7
0.8
0.9
1.0 -- -- --
P R-S
P R-S
R-S S-T
S U
T-U VW
W-W W-X
-- --
SYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTOR
21
System Effect CurveSystem Effect CurveSystem Effect CurveSystem Effect Curve
0.1
0.15
0.2
0.25
0.3
0.4
0.5
0.60.70.80.91.0
1.5
2.0
2.5
3.0
4.0
5.0
5 6 7 8 9 10 15 20 25 30 35 40 45
FGH IJ K L M N O
P
Q
R
S
T
U
V
W
X
AIR VELOCITY, FPM IN HUNDREDS(Air Density = 0.075 lbm/ft
3)
System Effect Factor (no duct) = 0.65 inches
System effect with 25% effective duct length =
0.15�WG
SYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTORSYSTEM EFFECTS FACTOR
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
� Outlet Ducts
� Outlet Diffusers
� Outlet Duct Elbows
� Turning Vanes
� Volume Control Dampers
� Duct Branches
OUTLET DUCTS - Centrifugal FanOUTLET DUCTS - Centrifugal Fan
� To calculate 100%
effective duct length,
assume a min. 2.5 duct
dia. for 12.7m/s or less.
Add 1 duct dia. for each
additional 5m/s.
No Duct 12% Effective Duct
25% Effective Duct
50% Effective Duct
100% Effective Duct
Pressure Recovery 0% 50% 80% 90% 100%
Blast Area / Outlet Area System Effect Curve
0.4 P R-S U W ---
0.5 P R-S U W ---
0.6 R-S S-T U-V W-X ---
0.7 S U W-X--- --- ---
0.8 T-U V-W X --- ---
0.9 V-W W-X --- --- ---
1.0 --- --- --- --- ---
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
22
OUTLET DUCTS � Axial FanOUTLET DUCTS � Axial Fan
� To calculate 100% effective duct length, assume a min. 2.5 duct dia. for 12.7m/s or less. Add 1 duct dia. for each additional 5m/s.
No Duct
12% Effective
Duct
25% Effective
Duct
50% Effective
Duct
100% Effective
Duct
Tubeaxial fan --- --- --- --- ---
Vaneaxial fan U V W --- ---
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
OUTLET DIFFUSERSOUTLET DIFFUSERS
� Outlet DIFFUSER is a connection piece between fan outlet and duct which allows the airstream to expand gradually.
� In many systems it may be feasible to use an outlet duct which is equal or close to the fan outlet. In these case the static pressure available to overcome the system resistance can be increased by converting some of the fan�s outlet velocity pressure to static pressure
--- static regain.
� The efficiency of conversion will depend upon the angle of expansion, the length of the diffuser section, and the blast area / outlet area ratio of the fan.
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
90# Elbow
No Duct
12% Effective
Duct
25% Effective
Duct
50% Effective
Duct
100% Effective
Duct
Tubeaxial fan 2&4 Pc --- --- --- --- ---
Vaneaxial fan 2 Pc U U-V V W ---
Vaneaxial fan 4Pc W --- --- --- ---
�� Axial FanAxial FanOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
OUTLET DUCTS ELBOWS
OUTLET DUCTS ELBOWS
23
OUTLET DUCTS ELBOWSOUTLET DUCTS ELBOWSOUTLET DUCTS ELBOWSOUTLET DUCTS ELBOWSBlast Area Outlet Area
Outlet Elbow Pos.
No Outlet Duct
12% Effective
Duct
25% Effective
Duct
50% Effective
Duct
100% Effective
Duct
0.4
A
B
C
D
N
M-N
L-M
L-M
O
N
M
M
P-Q
O-P
N
N
S
R-S
Q
Q
0.5
A
B
C
D
O-P
N-O
M-N
M-N
P-Q
O-P
N
N
R
Q
O-P
O-P
T
S-T
R-S
R-S
0.6
A
B
C
D
Q
P
N-O
N-O
Q-R
Q
O
O
S
R
Q
Q
U
T
S
S
0.7
A
B
C
D
R-S
Q-R
P
P
S
R-S
Q
Q
T
S-T
R-S
R-S
V
U-V
T
T
0.8
A
B
C
D
S
R-S
Q-R
Q-R
S-T
S
R
R
T-U
T
S
S
W
V
U-V
U-V
0.9
A
B
C
D
T
S
R
R
T-U
S-T
S
S
U-V
T-U
S-T
S-T
W
W
V
V
1.0
A
B
C
D
T
S-T
R-S
R-S
T-U
T
S
S
U-V
U
T
T
W
W
V
V
�� Centrifugal FanCentrifugal Fan
No
Syst
em E
ffec
t Fac
tor
� System Effect Curves for SWSI Fans
For DWDI Fans determine SEF using the curve for SWSI fans. Then apply the appropriate multiplier as follows:-ELBOW POSITION A = dP x 1.00
ELBOW POSITION B = dP X 1.25
ELBOW POSITION C = dP x 1.00
ELBOW POSITION D = dP x 0.85
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
TURNING VANESTURNING VANES
� Turning Vanes will usually reduce the pressure loss through an elbow.
� However, where a non-uniform approach velocity profile exists at a fan outlet,the vanes may actually serve to continue the non-uniform profile beyond the elbow.
� This may result in increased losses in other system components downstream of the elbow.
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
VOLUME CONTROL DAMPERSVOLUME CONTROL DAMPERS
Blast Area / Outlet Area
Pressure Drop Multiplier
0.4 7.5
0.5 4.8
0.6 3.3
0.7 2.4
0.8 1.9
0.9 1.5
1.0 1.2
PARALLEL BLADED DAMPEERILLUSTRATING DIVERTED FLOW
OPPOSED BLADED DAMPEERILLUSTRATING NON-DIVERTING FLOW
Pressure Drop Multiplier for Volume control dampers on a fan discharge
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
24
TYPICAL HVAC UNIT CONNECTIONTYPICAL HVAC UNIT CONNECTION
OUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORSOUTLET SYSTEM EFFECT FACTORS
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
� Inlet Ducts
� Inlet Duct Elbows
� Inlet Boxes
� Inlet Vortex (Spin or Swirl)
� Inlet Turning Vanes
� Airflow Straighteners
� Enclosures (Plenum and Cabinet Effects)
� Obstructed Inlets
INLET DUCTS ELBOWSINLET DUCTS ELBOWS �� Axial FanAxial Fan
H/T 90o Elbow No Duct [1][2] 0.5 D [1][2] 1.0 D [1][2] 3.0 D
Tubeaxial fan 0.25 2 pc U V W ---
Tubeaxial fan 0.25 4 pc X --- --- ---
Tubeaxial fan 0.35 2 pc V W X ---
Vaneaxial fan 0.61 2 pc Q-R Q-R S-T T-U
Vaneaxial fan 0.61 4 pc W W-X --- ---
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
25
INLET DUCTS ELBOWSINLET DUCTS ELBOWS �� Centrifugal FanCentrifugal Fan
� Non-uniform flow into a fan inlet induced by a 90o, 3-piece section elbow � no turning vanes.
� Non-uniform flow induced into fan inlet by a rectangular inlet duct.
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
INLET DUCTS ELBOWSINLET DUCTS ELBOWS �� Centrifugal FanCentrifugal Fan
� System Effect Curves for Various Mitered Elbows Without Turning Vanes
� System Effect Curves for Various Square Duct Elbows
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
INLET VORTEX (SPIN OR SWIRL)INLET VORTEX (SPIN OR SWIRL)
� Example of a Forced Inlet Vortex � Inlet Duct connections causing inlet spin
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
26
INLET TURNING VANESINLET TURNING VANES
� Corrections for Inlet Spin
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
ENCLOSURESENCLOSURES �� Plenum and Cabinet EffectsPlenum and Cabinet Effects
L Distance Inlet to Wall
System Effect Curves
0.75 x DIA of Inlet V-W
0.5 x DIA of Inlet U
0.4 x DIA of Inlet T
0.3 x DIA of Inlet S
� System effect curves for fans located in Plenums and cabinet Enclosures and for various wall to inlet dimensions.
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
Introduction
Kruger Inline Fan
CFT Cabinet Fan
The distance between the enclosure wall and fan inlet is about 0.5 of inlet diameter;
New design was improved to 0.85 & above of inlet diameter to reduce cabinet effect and improve the performance of the units
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Introduction
Introduction
As recommended by AMCA,if the L DISTANCE (fan inletto enclosure wall) is less than0.8 diameter of inlet we needto consider the SYSTEME F F E C T - t h e s h o r t e rd i s t a n c e , t h e mo r e t h eSYSTEM EFFECT on the fanperformance at same airv e l o c i t y .
Performance Comparison of Cabinet Fan 450
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Performance Comparison of Cabinet Fan 450
Performance Comparison of Cabinet Fan 450
OBSTRUCTED INLETSOBSTRUCTED INLETS
% of Unobstructed Inlet Area
System Effect Curves
100 No Loss
95 V
90 U
85 T
75 S
50 Q
25 P
INLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORSINLET SYSTEM EFFECT FACTORS
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2003 ASHRAE Applications HandbookTable 17 Approximate Silencer System Effect Factors
Silencer Condition
Pressure
Drop Factor*
Inlet (within 3 to 4 duct diameters)
Straight unobstructed duct 1.0
Free air/plenum with smooth inlet 1.05
Radius elbow (with turning vanes) 1.05
Radius elbow (no turning vanes) 1.1
Miter elbow 1.3
Free air/plenum with sharp inlet 1.1 to 1.30
Fan 1.1 to 1.3
2003 ASHRAE Applications Handbook
Silencer Condition
Pressure
Drop Factor*
Outlet (within 3 to 4 duct diameter)
Straight unobstructed duct 1.00
Duct doubles area abruptly 1.4
Radius elbow (with turning vanes) 1.5
Radius elbow (no turning vanes) 1.9
Miter elbow 2.0
Abrupt expansion/plenum 2.0
Fan 1.2 to 1.4
*Silencer pressure drop (including system effects) = silencer pressure drop per test code x pressure drop factor (inlet) x pressure drop factor (outlet).
PRESSURE GRADIENTS PRESSURE GRADIENTS �� Fan as TestedFan as TestedPRESSURE GRADIENTS PRESSURE GRADIENTS �� Fan as TestedFan as Tested
C-D duct friction 750 Pa (duct design)
A free inlet 0 Pa (no SEF)
B-C outlet with straight duct attached for 2 or more dia. 0 Pa (no SEF)
--------------------
REQUIRED Fan Ps 750 Pa
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PRESSURE GRADIENTS PRESSURE GRADIENTS �� Plenum EffectPlenum EffectPRESSURE GRADIENTS PRESSURE GRADIENTS �� Plenum EffectPlenum Effect
E-F duct friction at 5000CMH (Q) 750 Pa (duct design)
E contraction loss-plenum to duct 50 Pa (part of duct system)
E Ps energy required to create velocity at E 125 Pa (part of duct system)
D Pv loss (also Pt loss) at D as result of air velocity decrease 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 925 Pa
PRESSURE GRADIENTS PRESSURE GRADIENTS �� Abrupt Expansion Abrupt Expansion at Fan Outletat Fan OutletPRESSURE GRADIENTS PRESSURE GRADIENTS �� Abrupt Expansion Abrupt Expansion at Fan Outletat Fan Outlet
D-E duct friction at 5000CMH (Q) 750 Pa (duct design)
D contraction loss-plenum to duct 50 Pa (part of duct system)
D Ps energy required to create velocity at D 125 Pa (part of duct system)
B-C SEF 150 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 1075 Pa
PRESSURE GRADIENTS PRESSURE GRADIENTS �� Exhaust SystemExhaust SystemPRESSURE GRADIENTS PRESSURE GRADIENTS �� Exhaust SystemExhaust System
A Entrance loss-sharp edge duct 100 Pa (duct design)A-B Duct friction at 5000CMH 750 Pa (duct design)B SEF 1 150 Pa C SEF 2 50 Pa E Fan Pv 125 PaE SEF 3 150 Pa
------------------REQUIRED Fan Pt 1325 Pa
Fan Ps = fan Pt � fan PvFan Ps = 1325 Pa � 125 PaFan Ps = 1200 Pa
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Teoh Kee HinKruvent Industries (M) Sdn [email protected]: http://www.krugerfan.com