Civil Engineering Reference
In-Depth Information
10.4
Comparison Between Dissipative
and Non-dissipative Regulation Methods
An example of procedures for comparing some regulation methods is given below.
The details of the calculations are set out in Sect.
10.6
.
Figure
10.9
shows the situations to compare. The load curve is given together
with characteristic pump curves (see Fig.
10.10
), corresponding to a fixed
speed (in this figure it is 3,550 r/min). The design working point is shown as
A
n
(
q
n
;
H
n
;
η
n
).
A reduction of the design flow rate to 50 % is required. The working point should
move from point
A
n
to
A
1
(
q
1
¼
0.5
q
n
;
H
1
;
η
1
) always along the load curve to
reach the new working condition.
Two alternative procedures are considered:
• Use of a dissipative regulation that modifies the load curve at constant speed by
introducing a throttling valve. The new working point
is now point
A
2
η
2
) with the same flow as point
A
1
but with increased
head. This head increase corresponds to a required shaft power:
(
q
2
¼
0.5
q
n
;
H
2
;
Fig. 10.9
Working points with dissipative and non-dissipative regulation (see the example in
Sect.
10.6
)
