Visualization and evaluation of flow during water filtration: Parametrization and sensitivity analysis

1. Visualization and evaluation of a
filtration process in a laser sheet:
Parametrization and sensitivity analysis
Petr Bílek
Experimental
Fluid Mechanics 2015

2. Content of the presentation
• Introduction and motivation
– Visualization of filtration process
– Filtration setup
– Sensitivity analysis
– Parameterization
– Results
• Conclusion
2EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

3. Introduction and motivation
3
Introduction
• Using an optical method for:
• Visualization of the whole filtration process
• Measurement of the local filtration efficiency
Motivation
• Water filtration, testing nanofibrous filters
• Investigation of filter structure
• Determination of filter homogeneity
• Detection of ruptures
• Visualization of cleaning process
• Visualization of mechanical stress of a filter
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

4. Visualization of filtration process
4
Hardware construction of the method is inspired by PIV/PLIF method
• Filter between two glass channels
• Testing particles dispersed in water
• Continuous laser sheet 100 mW
• Lens Samyang 35 mm, F1.4
• Camera, CCD, 1920 × 1080 px
• 16 bit depth RAW format
Image analysis – determination of:
• Local number of particles
• Local light intensity
Calculation of filtration efficiency
in time and position
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

5. Typical picture from the camera
5
downstreamfilterupstream
1 cm
filtration channel
0.69 µm polystyrene
particles, 100 µg/liter
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

6. Calculation of filtration efficiency
Mass concentration:
C2 [µg/l] – behind a filter
C1 [µg/l] – in front of the filter
Light intensity:
I [W/m2]
Mean digital gray value:
Y [-]
100
1
2
1[%]
C
C
EF
YIC
The relation C(Y) is know for
every investigative area in an
image from calibration.
6
1) Illuminated testing
particles in front of the
filter
2) Sample of a filtration
textile
3) Investigation area for
image analysis
4) Illuminated testing
particles behind the filter
5) Filtration channel
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis
concentration
C(Y)

7. Scheme of the filtration setup
7
Parameters:
• Size of samples: 5 × 5 cm
• Pressure drop: 0 - 100 kPa
• Flowrate: 0 - 20 dm3 per minute
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis
θ
ϕ

8. Sensitivity analysis – camera elevation
8
Particle size
Ø [µm]
0.1 0.28 0.42 0.69 0.96 1.7 10
Sθ [% / °]
Monodisperse particles
0.5 7.5 4 4.9 4.1 6.3 120
Sθ [% / °]
Polydisperze p., Std. Dev. 2 %
0.54 7.48 3.88 4.51 3.33 2.95 6.71
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis
• According to Mie theory
• azimuth angle ϕ
• The method is not sensitive
• scattering angle θ
(angle between a source and a detector)
• The method is very sensitive
• Calculation of scattering function F
F(θ)

9. Sensitivity analysis – particle size
9
Particle size
Ø [µm]
0.1 0.28 0.42 0.69 0.96 1.7 10
SØ [-]
Monodisperse particles
5.6 0.9 3.7 8.9 5.5 10.1 91.1
SØ [-]
Polydisperze, Std. Dev. 2 %
5.71 0.79 3.67 8.73 5.47 9.29 9.80
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis
• Change of the particle size
• Swelling
• Dissolving
• Agglomeration
• Decomposition
F(θ)

10. Parameters
• Variation coefficient × size of investigation area
• Several sizes of particles
σcm – standard deviation, Cm – mean mass concentration
10
0
5
10
15
20
25
30
35
40
45
50
1 10 100
VariationcoefficientCv/%
Size of an evaluative area Ox / px
0.28 µm 0.42 µm 0.69 µm 0.96 µm 1.7 µm
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis
Ox [px]
Ox [px]
Size of evaluative area

11. Parameters
11
Particle size
Resolution
[µg/dm3]
Sensitivity
[dm3/μg]
Range
[µg/dm3]
0.28 µm 0.03897 26 0.04 - 2620
0.42 µm 0.06104 17 0.06 - 3932
0.69 µm 0.07484 13 0.08 - 5242
0.96 µm 0.08098 12 0.08 - 5242
1.7 µm 0.10841 10 0.1 - 6553
Size of the object
Size of the
evaluative area in
an image
Ox × Oy
Binning
Image
resolution
Size of the evaluative
area in the object [µm]
9.8 × 5.5 mm
1 × 1
1 × 1 1920 × 1080 50.9 × 50.9
2 × 2 960 × 540 101.9 × 101.9
5 × 5
1 × 1 384 × 216 254.5 × 254.5
2 × 2 192 × 108 509 × 509
20 × 20
1 × 1 96 × 54 1019 × 1019
2 × 2 48 × 27 2037 × 2037
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

12. Conclusion
12
Summary
• The optical method for investigation of a filtration process was discussed
• Sensitivity analysis was carried out and parameters were determined
Conclusion
• Sensitivity analysis
– Camera elevation against the laser sheet
– Size of testing particles
• High sensitivity - monodisperse particles, particles bigger than 1 µm
• Low sensitivity - polydisperse particles, submicron particles
• Parameters
– Size of testing particles: 0.1 – 100 µm
– Concentration of the particles: 0.05* (0.1**) – 2600 *(6500**) µg per dm3
*0.28 µm, **1.7 µm
– Image resolution: 48 × 27 - 1920 × 1080
– Size of an investigation area: 2 × 2 mm - 50 × 50 µm
EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

13. Acknowledgments
This work was supported by the Ministry of Education
of the Czech Republic within the SGS project
no. 21066/115 on the Technical University of Liberec.
13EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis

14. Thank you for your attention
14EFM 2015, Visualization and evaluation of a filtration process in a laser sheet: Parameterization and sensitivity analysis