2.7.4. Example with varying flow over 1 year
The example below is calculated on the basis of pump characteristics obtained from a pump da-
tasheet. (45 kW). The same examples of calculations can be used in the case of fan characteristics.
The result obtained is savings in excees of 50% at the
given flow distribution over a year, corresponding to 8,760 hours.
Typically, the example calculated below results in a pay-back period of one year - depending on
the price per kWh and the price of the frequency converter.
Pump characteristics
Energy savings
This figure compares power control via
valves and without speed control with
pressure control via a frequency convert-
er.
P
shaft
=P
shaft output
Flow distribution over 1 year
m
3
/h Distribution
Valve
regulation
Frequency converter control
%
Hours
Power Consumption
Power
Consumption
A
1
- B
1
kWh
A
1
- C
1
kWh
350
5
438
42,5
18.615
42,5
18.615
300
15
1314
38,5
50.589
29,0
38.106
250
20
1752
35,0
61.320
18,5
32.412
200
20
1752
31,5
55.188
11,5
20.148
150
20
1752
28,0
49.056
6,5
11.388
100
20
1752
23,0
40.296
3,5
6.132
Σ
100
8760
275.064
26.801
2. Introduction to VLT HVAC Drive
VLT
®
HVAC Drive Design Guide
18
MG.11.B2.02 - VLT
®
is a registered Danfoss trademark
2
Содержание VLT series
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