Fan Efficiency Grades and Their Effects on Laboratory … Rocky Mountain Chapter Fan Efficiency...

ASHRAE Rocky Mountain Chapter

Fan Efficiency Grades and System Effect and Their Effects

on HVAC Systems

Matt Spink, P.E. Greenheck Fan Corporation


Learning Objectives

• Understanding Fan Efficiency Grades (FEG) • Selection of fans within acceptable efficiency

tolerances • System Effect: Understanding their impact on

performance/energy


Background • US total energy consumption for 2010…

98 Quadrillion BTUs! (1.0 quadrillion = 1,000,000,000,000,000 BTUs)

• According to the DOE US fans consume:

– 0.9 quads of electricity in industrial applications – 1.6 quads of electricity in commercial applications (2.5 quads is about 2.5% of total) * Sources: DOE and LLNL


Background

Source: AMCA International

Fan Efficiency

Drive Efficiency

Fan Selection

System Effects

System Leakage

Savings Potential in HVAC Systems


Background

2007 2008 2009 2010 2011 2012 2013

• DOE suggests 65% fan efficiency.

• ASHRAE & AMCA collaborate on AMCA 205 – Fan Efficiency Grades.

AMCA 205-10 Fan

Efficiency Classification

For Fans

ASHRAE 90.1 adopted

– FEG 67

• AMCA begins certifying FEGs

• 2012 IgCC adopts FEG 71

• DOE publishes intent to regulate fan energy efficiency


Fan Energy Consumption

Power Input (Electrical)

Power Output (Flow and Pressure)

Power Loss !


Fan Energy Consumption

Electrical Power

In

Motor Loss

(10%)

Drive Loss (3% -10%)

Bearing Loss (3%)

Aerodynamic Loss

(10% to 20%)

Fan Power

Out

Fan Efficiency


What is Fan Efficiency?

Power Output Efficiency = Power Input

CFM x Pressure Fan Efficiency = BHP


What is Fan Efficiency? CFM x Ps Static Efficiency = x 100% 6343.3 x BHP

PT = PS + PV

CFM x Pt Total Efficiency = x 100% 6343.3 x BHP


Fan Curves

0.0

2.0

4.0

6.0

8.0

10.0

0 2 4 6 8 10 12 CFM x 1000

Ps

Ps vs. CFM

BHP vs. CFM

0.0

1.0

2.0

3.0

4.0

5.0

6.0

BH

P Surge Area


Fan Curves

0

20

40

60

80

100

0 2 4 6 8 10 12 CFM x 1000

Ps

Ps vs. CFM

Static Efficiency vs. CFM

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Eff

icie

ncy Peak 75%


Fan Selection for Efficiency

0.0

2.0

4.0

6.0

8.0

10.0

0 2 4 6 8 10 12 CFM x 1000

Ps

0.0

1.0

2.0

3.0

4.0

5.0

6.0

BH

P

Ps

BHP Surge Area

High Efficiency, Low Sound

Low Efficiency, High Sound


CFM

Ps


Design Duty 27

24

22

20

18

30


% CFM


% Ps

Static Efficiency

Peak

SE

High Efficiency, Low Sound

Actual Selections


Fan Efficiency Grades

• ANSI/AMCA Standard 205-10 – Energy Efficiency Classifications for Fans

• ISO 12759:2010 Fans – Efficiency Classification for Fans


Fan Efficiency Grades AMCA 205

85


Fan Efficiency Grades AMCA 205

Airfoil Centrifugal

Backward Inclined

Forward Curved


AMCA 205

AMCA 205, Annex A: In order to achieve the goals in energy savings by

operating fans it is important that the fan is selected in the system close to the peak of the fan efficiency. The fan operating efficiency at all intended operating point(s) shall not be less than 15 percentage points below the fan peak total efficiency (see figure).


Fan Efficiency Grades

0

20

40

60

80

100

0 2 4 6 8 10 12 CFM x 1000

Ps

Ps vs. CFM

Total Efficiency vs. CFM

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Eff

icie

ncy Peak 75%


Fan Curves

0

20

40

60

80

100

0 2 4 6 8 10 12 CFM x 1000

Ps

Ps vs. CFM

Total Efficiency vs. CFM

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Eff

icie

ncy

60% Minimum within 15 points of

peak efficiency


ASHRAE 90.1 Addendum u 6.5.3.1 Fan System Power and Efficiency Limitation 6.5.3.1.3 Fan Efficiency. Fans shall have a Fan Efficiency Grade (FEG) of 67

or higher based on manufacturers’ certified data, as defined by AMCA 205. The total efficiency of the fan at the design point of operation shall be within 15 percentage points of the maximum total efficiency of the fan.

Exceptions: a. Single fans with a motor of 5 hp or less. b. Multiple fans in parallel or series that have a combined motor power of 5

hp or less and are operated as the functional equivalent of a single fan. c. Fans that are part of equipment listed under 6.4.1.1 Minimum Equipment

Efficiencies – Listed Equipment – Standard Rating and Operating Conditions.

d. Fans included in equipment bearing a third-party-certified seal for air or energy performance of the equipment package.

e. Powered wall/roof ventilators (PRV) as defined by ANSI/AMCA-99-2010.


International Green Construction Code 2012 IgCC

CHAPTER 6 607.2.2.3 Minimum fan efficiency. Stand-alone supply, return and exhaust fans designed for operating with motors over 750 watts (1hp) shall have an energy efficiency classification of not less than FEG71 as defined in AMCA 205. The total efficiency of the fan at the design point of operation shall be within 10 percentage points of either the maximum total efficiency of the fan or the static efficiency of the fan.


“Things are not always as they seem; the first appearance deceives many.”

- Phaedrus (Roman Poet)


60”

49”

54”

54”

54”

Impeller Dia

6.8

13.4

6.87

8.30

7.11

BHP

90

90

75

67

56

FEG

6.1

3.8

4.4

1.7

1.0

$ Cost

Housed Centrifugal

Housed Centrifugal

Vane Axial

Tube Axial

Sidewall Prop

Model

Fan Types 40,000 CFM at 0.25” Ps


Fan Types

28

Adhering to codes that require minimum Fan Efficiency Grades will result in replacing this:


Fan Types

29

With this:


12.0

12.5

13.6

16.2

19.0

24.5

Oper BHP

78%

75%

70%

58%

50%

38%

Static Eff

83%

82%

79%

70%

64%

55%

Total Eff

78%

78%

78%

74%

74%

75%

Peak Static

Eff

83%

83%

83%

79%

79%

79%

Peak Total Eff

85

85

85

85

85

85

FEG

36

33

30

27

24

22

SW Airfoil Centrifugal

I

I

II

II

III

III

Fan Class

Fan Selections 15,000 CFM at 4” Ps


Summary

• New standards are going to require Fan Efficiency Grades

• FEGs are an indicator of Peak Total Efficiency, not of Fan input power

• For fan comparison and selection, use the actual Fan BHP

• Future standards will likely start to look at installed systems, not just individual components


System Effects

34


Design Airflow

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 CFM x 1000

Ps

Catalog Fan Curve

Design System Curve


Fan Curves • Show how a fan will operate in any system (installation) • Based on standardized tests

– AMCA 210

• Tested under ideal conditions


System Effects Defined:

•Anything you place in close proximity before or after the fan that effects the cataloged performance.

38


System Effects


Actual Airflow

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 CFM x 1000

Ps

Catalog Fan Curve

System Curve

Actual Fan Curve


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

41


Three most common causes of deficient performance of a fan/system are:

• Improper outlet connections

• Swirl at the inlet

• Non-uniform inlet flow

42


Fan Outlet Velocity Profiles

43

Blast Area Cut off

25%

50%

75%

100% Effective Duct Length

Outlet Area

Discharge Duct

Centrifugal Fan

Axial Fan

Adapted from AMCA Publication 201-202, Fans and Systems.


Effective Duct Length

Effective Duct Length = 2.5 Duct Diameters for 2,500 FPM or less

Add 1 duct diameter for each additional 1,000 FPM

44

For rectangular ducts, the equivalent duct diameter is

(4 x width x length / 3.14) ^ 0.5


System Effect

Curve

45

1

2

3

2 Adapted from AMCA Publication 201-202, Fans and Systems.


System Effect Curves for Outlet Ducts - Centrifugal Fans

46

1 0 0 % E f f e c t i v e D u c t L e n g t h

B l a s t A r e a

N o D u c t

1 2 % E f f e c t i v e

D u c t

2 5 % E f f e c t i v e

D u c t

5 0 % E f f e c t i v e

D u c t

1 0 0 % E f f e c t i v e

D u c t

B l a s t A r e a D i s c h a r g e D u c t

O u t l e t A r e a C u t o f f

U W - -

S y s t e m E f f e c t C u r v e

U W - - U - V W - X - - W - X - - - -

X - - - -

- - - - - -

0 . 4 O u t l e t A r e a

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 V W

W - W W - X - - - -



System Effect

Curve

47

1

2

3 +0.45 in w.g.



Thank you for your time.

Questions?

49


-+

50

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Fan Efficiency Grades and Their Effects on Laboratory … Rocky Mountain Chapter Fan Efficiency...

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