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Fans & Blowers
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Fans & Blowers
Introduction
Types of fans and blowers
Assessment of fans and blowers
Energy efficiency opportunities
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Energy Efficiency Opportunities
1. Choose the right fan
2. Reduce the system resistance
3. Operate close to BEP
4. Maintain fans regularly
5. Control the fan air flow
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Energy Efficiency Opportunities
a) Dampers
b) Pulley change
c) Inlet guide vanes
d) Variable pitch fans
e) Variable speed drives (VSD)
f) Multiple speed drive
g) Disc throttle
h) Operating fans in parallel
i) Operating fans in series
5. Control the Fan Air flow
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Energy Efficiency Opportunities
a) Dampers: reduce flow and increase
upstream pressure
Types:
• Louvered Damper
• Radial Damper
• Vortex Damper
• Variable Inlet Vane (VIV)
5. Control the Fan Air flow
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Energy Efficiency Opportunities
a) Dampers:
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
5. Control the Fan Air flow
b) Pulley change:
• Pulley & Belt Drives
• Possible to have various combinations of
pulleys (sheaves) & belt drives on the
motor and the fan to vary the fan speed
• Driven by a single-speed motor.
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Energy Efficiency Opportunities
5. Control the Fan Air flow
b) Pulley & Belt Drives:
• A convenient way of reducing the
rotational speed of fans
• usually designed to operate under 1,800
rpm
• The belt transfers the power from the
motor to the fan, and changes the fan
speed relative to the motor speed
according to the desired pulley ratio.
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Energy Efficiency Opportunities
5. Control the Fan Air flow
b) Pulley & Belt Drives: Types of Drives
The four principal types of belts are:
• Flat belts;
• V-belts;
• Cogged V-belts; and,
• Synchronous belts.
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Energy Efficiency Opportunities
b) Pulley change: reduce motor/drive pulley
size
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
(BEE India, 2004)
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Energy Efficiency Opportunities
c) Inlet guide vanes
• Create swirls in fan direction
• Reduce angle air and fan blades
• Lowering fan load, pressure, air flow
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
d) Variable pitch fans: changes angle
incoming airflow and blades
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
e) Variable speed drives (VSDs): reduce
fan speed and air flow
• Two types
• Mechanical VSDs
• Electrical VSDs (including VFDs)
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
e) Variable frequency drives
• Change motor’s rotational speed by
adjusting electrical frequency of power
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
f) Multiple speed drive
• Changes fan speed from one speed to
other speed
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
g) Disc throttle:
Sliding throttle that changes width of
impeller exposed to air stream
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
h) Operate more fans in parallel (instead of
one large fan)
• Advantages/ Disadvantages…
…..on Blog…..
5. Control the Fan Air flow
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Energy Efficiency Opportunities
i) Operate fans in series
• Advantages
• Lower average duct pressure
• Less noise
• Lower structural / electrical support required
• Disadvantages
• Not suited for low resistance systems
5. Control the Fan Air flow
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Energy Efficiency Opportunities
5. Controlling the Fan Air Flow
Comparing
Fans in
Parallel
and Series
(BEE India, 2004)
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Energy Efficiency Opportunities
(BEE India, 2004)
5. Controlling the Fan Air Flow
Comparing
the impact of
different types
of flow control
on power use
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Assessment of fans and blowers
Some Clues:
• High operating cost;
• High maintenance cost;
• High level of noise;
• High air leakage in ducting or system;
• Inadequate air flow through certain
branches; or
• Inability to adjust flow rates according to
production needs.
Identification of Inefficient F & Bs
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Assessment of fans and blowers
caused by…
• inefficient fan operation,
• improper fan selection (usually oversizing
for the application),
• operation in the wrong pressure range,
• poor system design,
• wasteful air flow control choices and
• operation when not needed.
High operating cost
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Assessment of fans and blowers
• Belt slippage is not only wasteful of
energy, but also results in excessive
wear and early failure of the belt and
pulleys.
• Belt over-tightening results in higher
energy consumption, excessive wear on
the bearings and early belt and bearing
failure.
High maintenance cost
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Assessment of fans and blowers
• Soft starters can extend fan motor life
by keeping the motor temperature lower.
• Variable frequency drives (VFDs) are
also commonly used to soft start fans by
gradually bringing fan speed up to
operating conditions.
High maintenance cost
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Assessment of fans and blowers
• oversized fans, or
• with the wrong type of fan for the
application
High level of noise
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Assessment of fans and blowers
Due to poorly designed or maintained
ducting or equipment, stuck dampers or
other reasons.
The result is more fan power required.
High air leakage in ducting or
system
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Assessment of fans and blowers
Due to inadequate balancing and duct
configurations.
Inadequate air flow through certain
branches
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Assessment of fans and blowers
The use of dampers to block or by-pass air
flow is very inefficient and causes more
power to be drawn by the fan.
Inability to adjust flow rates as per
need
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Assessment of fans and blowers
When air flow requirements change with
time…
..a single fan may be forced to operate far
away from the BEP over long periods of
time…
reduce the fan efficiency.
What are the options to avoid it??
How to avoid overdesign in Fans
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Assessment of fans and blowers
options :
• Multiple fans in series or parallel;
• Replacing fans with a more appropriate
type for the load;
• Better matching of fans/blowers to motors
How to avoid overdesign in Fans
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Assessment of fans and blowers
• Multiple fans in series or parallel;
• In parallel or series?- depends on
requirement
•Installed in series close to each other:
increase pressure locally or
•Installed in series far apart: increase
pressure in different parts of the ductwork.
• Installed in parallel : varying the air
flow rate.
How to avoid overdesign in Fans
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Assessment of fans and blowers
• Multiple fans in series or parallel;
• In parallel or series?- depends on
requirement
• Fans in series in an induced-draft/ forced-
draft configuration minimize the amount
of pressurization in a duct or an
enclosure.
How to avoid overdesign in Fans
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Training Session on Energy
Equipment
Fans & Blowers
THANK YOU
FOR YOUR ATTENTION