Danfoss VLT HVAC Basic Drive FC 101 Design Manual page 15

Introduction to VLT® HVAC B...
2 2
Discharge
damper
Less energy savings
Costlier installation
Illustration 2.4 The Three Common Energy Saving Systems
100
80
60
40
20
0
0
Illustration 2.5 Energy Savings
Discharge dampers reduce power consumption somewhat.
Inlet Guide Vans offer a 40% reduction but are expensive
to install. The Danfoss frequency converter solution
reduces energy consumption with more than 50% and is
easy to install.
14
VLT
Maximum energy savings
IGV
Discharge Damper Solution
IGV Solution
VLT Solution
60 0 60 0
Volume %
MG18C402 - VLT
®
HVAC Basic Drive Design Guide
2.6.5 Example with Varying Flow over 1
Year
This example is calculated based on pump characteristics
obtained from a pump datasheet.
The result obtained shows energy savings in excess of 50%
at the given flow distribution over a year. The pay back
period depends on the price per kWh and price of
frequency converter. In this example it is less than a year
when compared with valves and constant speed.
Energy savings
P =P
shaft shaft output
Flow distribution over 1 year
Illustration 2.6
(mwg)
60
50
40
30
20
10
60
(kW)
60
50
40
30
20
10
Illustration 2.7
®
is a registered Danfoss trademark
H
s
B
A
1350rpm
C
1050rpm
750rpm
0 100 200 300
P
shaft
A
1350rpm
B 1
1050rpm
C 1
750rpm
0 100 200 300
1650rpm
( 3 )
m /h
400
1
1650rpm
( 3 )
400 m /h