fan & system

31
1 Contents 1. Fan Type 2. Fan Type Selection 3. Fan Selection 4. Fan Efficiency 5. Fan & Air System 6. Fan Operating Range 7. AMCA 8. Fan Testing 9. Deficient Performance 10. System Effect 11. System Effect Movies 12. System Effect Factor 13. Outlet System Effect Factor 14. Inlet System Effect Factor 15. Example Axial Mixed Flow Centrifugal Fan Type

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Page 1: Fan & System

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

Page 2: Fan & System

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

Page 3: Fan & System

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

Page 4: Fan & System

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]

Page 5: Fan & System

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

Page 6: Fan & System

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)

Page 7: Fan & System

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.

Page 8: Fan & System

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

Page 9: Fan & 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

Page 10: Fan & 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

Page 11: Fan & System

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

Page 12: Fan & System

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

Page 13: Fan & System

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

Page 14: Fan & System

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

Page 15: Fan & System

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

Page 16: Fan & System

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

Page 17: Fan & System

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

Page 18: Fan & System

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)

Page 19: Fan & System

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

Page 20: Fan & System

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

Page 21: Fan & System

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

Page 22: Fan & System

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

Page 23: Fan & System

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

Page 24: Fan & System

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

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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

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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