Civil Engineering Reference
In-Depth Information
Table 10.1
Comparison between dissipative and non-dissipative methods (see Figs.
10.9
and
10.10
)
At reduced capacity (50 %)
At rated capacity
(100 %)
Non-dissipative
method (II)
Dissipative method (I)
SI units
Working point
Working point
Working point
(a)
a
m
3
/min
Capacity
A
n
0.312
A
1
,
A
2
0.16
A
1
0.16
m
3
/s
a
0
¼ a
/60
0.005
0.0027
0.0027
b
Head (basic load)
m
A
n
53.20
A
1
37.50
A
1
37.50
c
m
A
2
67.00
d
Pump efficiency
%
A
n
49.00
A
2
38.00
A
1
(
A
1n
)
44.00
a
0
b
9
:
81
r
1, 000
Power delivered to the end user circuit
kW
A
n
2.72
A
1
0.98
A
1
0.98
e ¼
a
0
c b
ð
Þ
9
:
81
r
1, 000
Regulating losses
Valve losses at pump shaft
f ¼
kW
0
A
2
A
1
0.77
0
g¼ f
100/
d
Valve losses at pump shaft
kW
0
A
2
A
1
2.03
0
h
¼
g
+
e
100/
d
Total shaft pump power
kW
A
n
5.54
A
2
4.61
A
1
2.23
i
Electric motor efficiency
%
90.00
90.00
90.00
l ¼ h
(100/
i
1)
Electric motor losses
kW
A
n
0.62
A
2
0.51
A
1
0.25
m
Drive control losses
kW
0.00
0.00
A
1
0.28
Electric power
n¼m
+1+
h
Supplied by the line
kW
A
n
6.16
A
2
5.12
A
1
2.75
o
Working hours
h/year
A
n
8,640
A
2
8,640
A
1
8,640
Electric energy
p¼ no
Supplied by the line
kWh/year
A
n
53,222
A
2
44,237
A
1
23,760
Energy saving at reduced capacity
q
¼
p
(I)
p
(II)
Method (I)
Method (II)
kWh/year
20,477
kg/m
3
r
Density of fluid
1,000
1,000
1,000
