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High spatial and temporal
resolution planar
capacitive sensing in oil-
water pipe flow
ADRIANA BONILLA RIAÑO
ADVISOR: DR. ANTONIO BANNWART
CO- ADVISOR: DR. OSCAR M. H. RODRIGUEZ
NOVEMBER 29, 2013
1
OUTLINE
• Holdup Estimation in Core Flow Using Image
Processing
• Film thickness measurement using infrared
images
• Planar sensor simulation
• Next steps
2
Holdup estimation in core flow using image processing
Oil-water core flow in a 62mm i.d. pipe
Heavy oil (2000 cP and 950 kg/m3 at 35 °C) and water.
4 experiments with 100 images each.
3
Algorithm
4
Pre-processing
• Cutting
• Noise Reduction
• Contrast enhancement
Algorithm
5
Segmentation
• Active
contours
• Mathematical
morphology
Algorithm
6
Volume Calculation
• Radius measurement
• Polynomial fit
• Integration
• Oil Holdup
4 3 2 1
3 2 1 0( )r x x a x a x a x a
2
0
( )
L
oV r x dx
2
oo
Vh
R L
L
x
Holdup correlation
7
0(1 ) (1 ) 0q m
os o ws o ref o oU h s U h cV h h
11
222 22 1
2 2
i
ii
i
n
nnn
ref i
gDDV a gD
7 3
4 2
i
i
nq
n
c,m, a, g, D, µ, ρ, n are constants From Rodriguez et al, 2006
Evaluation
Parameters
Fractional difference between areas (DFA)
Sensitivity (S)
Mean square error (MSE)
Number of sites of disagreement (NSD)
Holdup results
8
Holdup by
correlation
(Rodriguez et al,
2006)
Active Contours
Mathematical
Morphology
Holdup
Relative
error
% Holdup
Relative
error
%
Test 1
0.521 0.462 11.32 0.543 4.22
Test 2
0.812 0.625 23.03 0.804 0.98
Test 3
0.709 0.584 17.63 0.676 4.65
Test 4
0.814 0.693 14.86 0.797 2.09
Averag
e 16.71 2.98
Film thickness measurement using infrared images
• Rectangular channel with adjustable space
between the sensor and the wall in front of
it.
• Micrometer screws from 0 to 700 microns in
steps of 100 microns.
• Oil was added to the water and then
introduced as a flow on the top of the
channel
• The average measured values (using
conductance planar sensor) were compared
with the film thickness calculated by the
infrared images
9
Experiments
Test Vo (mL) Vw (mL) Average
Error [%]
Test 1 to Test 7
5 400
16.53
Test 8 to Test 14
10 400
20.68
Test 15 to Test 21
100 100
28.42
10
Im
Im
1( ) 100%S
N
F FARE abs
N F
Algorithm
11
Pre-processing:
Cutting
Segmentation:
Mathematical morphology
Film thickness
Calculation
Im
1WF N MP
NP
Vo
(mL)
Vw
(mL)
NP MP
5 400 11935 400
Results
12
10 20 30 40 50 60
5
10
15
0 100 200 300 400 500 600 700
Test 4. Micrometers position 400µm and average film
thickness by image 383.04µm and by sensor 373.28µm.
10 20 30 40 50 60
5
10
15
0 100 200 300 400 500 600 700
Test 14. Micrometers position 700µm and average film
thickness by image 613.7243µm and by sensor 611.295µm.
10 20 30 40 50 60
5
10
15
0 100 200 300 400 500 600 700
Test 20. Micrometers position 600µm and average film
thickness by image 531.53µm and by sensor
504.04µm.
Results
13
100 200 300 400 500 600 7000
100
200
300
400
500
600
700
Micrometers Position [m]
Wa
ter
Film
Th
ickn
ess
By Image Oil 5mL Water 400mL
By Sensor Oil 5mL Water 400mL
By Image Oil 10mL Water 400mL
By Sensor Oil 10mL Water 400mL
By Image Oil 100mL Water 100mL
By Sensor Oil 100mL Water 100mL
Planar sensor simulations
• Objetive: Find the best capacitive planar sensor geometry
• 5 geometries were tested
• Comparative features:
• maximum measurable thickness of the film,
• quasi-linear sensor characteristics
• spatial resolution.
• Calculation of the sensor characteristic is done by solving the
three-dimensional potential equation within the liquid film on
top of the sensor electrode system using Comsol.
14
Planar sensor geometries Geometry 1 Geometry 2 Geometry 3 Geometry 4
Geometry 5
15
Simulation results
100 200 300 400 500 600 700 800 900 1000
0.4
0.5
0.6
0.7
0.8
0.9
1
Film Thickness [m]
Dim
ensio
nle
ss C
apacitance [
-]
Geometry 1
Geometry 2
Geometry 3
Geometry 4
Geometry 5
16
NEXT STEPS
17
• Calibration of capacitive planar sensor
NEXT STEPS
18
•Sensor characterization: System Frequency response
•Sensor and camera setting-up in vertical 2” pipe
•Oil-Water tests (dispersed flow) in vertical pipe
•Water film thickness estimation by :
• Capacitive sensor
• High speed images
Acknowledgments
19
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