an experimental study of water flow in pipelines under influence of applied electrical dc-potentials...
TRANSCRIPT
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An experimental study of Water Flow in Pipelines
under Influence of Applied Electrical DC-Potentials
M. Waskaas
Telemark University College
Porsgrunn, Norway
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The idea and hypothesis
Given a pipeline made of electric conductive material, through which water containing ions, is flowing.
An electrical potential between the pipewall and fluid is established.
The electric force acts as a friction in addition to the mechanical and hydrodynamical friction for the flow.
If the potential is reduced, then this additional friction is also reduced, and the result is an increased flow rate near the pipewall.
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Advanced experimental setup - in principle
Water flow
Pumping water
DC-potential
Lase
r
Plexi glas
12.5 m
1.3 m
7.5 m 50 mm
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Application of the potential
Water flowWater flow
Water flowWater flow
Water flowWater flow
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Measured velocity profile with and without DC-potential
0
0,2
0,4
0,6
0,8
1
1,2
0 5 10 15 20 25 30 35 40
Relative units
Position inward from the pipe wall
Vmean= 1.0 m/s, Re = 50000
0
0,2
0,4
0,6
0,8
1
1,2
0 5 10 15 20 25 30 35 40
Position inward from the pipe wall
Relative units
Vmean= 0.5 m/s, Re = 25000
Vmean= 2.0 m/s, Re = 100000
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Addisional observation
Water flow
Pumping water
DC-potential
Lase
r
Plexi glas
Fouling
Clean
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Experimental setup – potential measurements
Reference electrode (R) Ag/AgCl
I
+
Applied potentials:
OCP, 0.5, 0.8 and 1.1 V
Uring(R)
U
U UPipe(R)
12.5 m
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Results – Potential distributionUpipe(R)
-1000
-800
-600
-400
-200
0
200
400
600
1 3 5 7 9
11
13
15
17
19
21
23
25
OCP [mV]: Upipe(R) URing(R)
V/ 0.8 V [mV]: Upipe(R) URing(R)
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Results
URing(R)0
50
100
150
200
250
300
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
1.1 V
0.8 V
0.5 V
U = Upipe(R) - Upipe, ocp(R)
Potential changes [mV] vmean = 1.0 m/s Potential changes [mV] vmean = 2.0 m/s
0
50
100
150
200
250
300
1 3 5 7 9 11 13 15 17 19 21 23 25
U = Upipe(R) - Upipe, ocp(R)
1.1 V
0.8 V
0.5 V
0
2
4
6
8
10
12
14
16
18
0 0,2 0,4 0,6 0,8 1 1,2
Current [A] V/ 1m/s Current [A] V/ 2m/s
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Full scale field experiment in a powerstation
12.5 MW, 85 GWh
Pelton turbine
Pipeline: L = 1600 m, D = 1 m
Head: 380 m
Head loss: 44.1 m
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Water
Reservoir
Turbine inlet
Applied DC-potential
Applied DC-potential on the pipeline in Vrenga powerstation
Pipeline
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The electric insulated manlock
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Head loss in tunnels and pipelines
Turbine
Head loss – 44.1 m
Flow Q
Head – 380 m
P1
P2
Active effect
Reactive effect
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Results – Head loss(Q2)
0
5
10
15
20
25
30
35
40
45
0 2 4 6 8 10 12 14 16 18 20 22 24
Hea
dlos
s [m
]
Q2 [m6/s2]Q2 [m6/s2]
Head loss [m]
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Results
Head loss is reduced by 13 %
Energy production is increased by 1.8 %
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Addisional observation
The fouling inside appears
to be reduced
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Summary
Increased water flow rate at the pipewall in a pipe when exposed to a particlular electric DC-potential is observed.
A gradient in the electrical potential distribution along the pipe has been measured. Maximum potentrial at the inlet. This holds for both exposed and unexposed to electric DC-potentials. In a hydroelectric powerstation:
A decrease in the head loss up to 14 %An increase in the power production up to 1.8 %
The study is still in progress.Experiments – water flow and potential measurementsTheoretical studies involving electrochemistry andfluid mechanics will be initiated
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Acknowledgement
I thank prof. V. Daujotis, Vilnius University, Lithuania; prof. K.Esbensen Aalborg University, Denmark; assoc. prof. K.E.Wolden, Telemark University College and tehnician Inger H. Matveyev, Telemark University College for assistance with the experiments.