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Studying the Characteristics of Bubble Motion in Pool Boiling in Microgravity Conditions Under the Influence
of a Magnetic Field.
by
Thilanka Munasinghe
West Virginia University,Morgantown, USA
RAST 2009 - Istanbul ,Turkey 1
The “Key” Terms :
• Pool Boiling
• Microgravity
• Bubble characteristics
• RAST 2009 - Istanbul ,Turkey 2
What is Pool Boiling ?
How can we do pool boiling ?
Pool Boling is a method of boiling and generating bubbles in a liquid that can boil in a container with a heat resource.
There are several ways that can do the pool boiling and one of the common ways is boiling in a cylindrical tank as we used in our experiment. RAST 2009 - Istanbul ,Turkey 3
What is “Microgravity” ?
micro level (10-6) = μ = 0.000001
g= 9.81 m/s2 ( Earth’s gravity level)
μ g= [0.000001] X [ 9.81 ] = 0.00000981 m/s2
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Pool Boiling in two identical tanks with a paramagnetic liquid
Paramagnetic liquid – MnCl2 (aq) + H2O
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Why We need a Paramagnetic Liquid?
In order to avoid the floating of the liquid inside the tank due to lack of gravity, paramagnetic liquid will be used to attach the liquid to the bottom surface of the tank by using a permanent magnet.
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Bubble Behavior
• Bubble’s travel path inside the tank.
• Size of the bubble ( vertical and horizontal radius).
• Bubble’s shape deformation comparatively to the original shape.
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How to create a “Microgravity” conditions artificially ?
Parabolic path of an aircraft can create “Microgravity” conditions within a short period of
time such as 20-30 seconds period in a one parabola.
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Parabolic path of the aircraft that can create microgravity condition
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Experiment apparatus before the flight
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Closer look of the experiment set up
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Boiling behavior during the microgravity period
Boiling in Earth’s
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Bubble’s coordinates on the perimeter
Three consecutive bubble frames
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Colour Images has converted to gray scale images and bubble location has determined.
(1) Colour image and Gray scale image
(2) Location of the bubble on gray scale image with respect to the colour image
(1) (2)
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0 0.02 0.04 0.06 0.08 0.10
500
1000
1500
2000
2500
3000
3500 Axial Distance Vs Magnetic Feild Strength
Axial Distance (m)
Ma
gne
tic
Fe
ild S
tre
ngt
h (
Ga
uss
)
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40 45 50 55 60 650
5
10
15
20
25
30
35
40
45
50 Bubble Possition Vs Frame Number
Frame Number
X-C
oord
inat
e of
the
Bubb
le P
ossi
tion
(pix
els)
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0 10 20 30 40 5020
40
60
80
100
120
140
160
180
200
220 Vertical Possition of the Bubble Vs Frame Number
Frame Number
Y-C
oord
inat
e of
the
Bub
ble
Pos
sitio
n (p
ixel
s)
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0 5 10 15 20 25 30 35 40 45 50
6
8
10
12
14
16
18
20
22 Radius Vs Frame Number
Frame Number
Bub
ble
R
adiu
s (p
ixel
s)
Vertical Radius
Horizontal Radius
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0 5 10 15 20 25 30 35 40 45 500
200
400
600
800
1000
1200
1400
Frame Number
Bubb
le Ar
ea (
pixe
l squ
ard
)
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Possible practical applications of Pool Boiling in microgravity
• Pool boiling in Microgravity conditions can use as a “Cooling Process” for out of Earth conditions specially inside the ISS (International Space Station)
• Space applications that are related to liquids and bubbles that related to many fields such as Space medicine, Space Agriculture, Heat transfer ..etc
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Conclusion:
• In microgravity conditions boiling process take place faster than Earth’s gravity.
• At the bottom of the tank the bubble’s vertical radius is comparatively smaller than the horizontal radius.
• As the bubble goes along the tank, the strength of the magnetic field reduces and eventually the vertical component of the radius gets bigger than the horizontal radius.
• While the bubble travels upwards, bubble movement demonstrates a 2-D spiral path along the tank.
• Horizontal and vertical radius, bubble area, bubble path along the vertical axis of the tank was graphed verses bubble frame number for the detailed characteristic study of bubbles.
• These bubbles also were observed to be elliptical and in real visualization it is in 3-D.
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A. Fujiwara, Y. Danmoto, K. Hishida, “Bubble Deformation and Surrounding Flow Structure Measured By PIV/LIV and Shadow image Technique”, ASME_JSME 4th Joint Fluid Engineering Conference, F E DSM200 3-4 5674, Honolulu, Hawaii, USA, July 2003. S. Toshiyuki, M. Watanabe,T. Fukano, “Study On Single Bubble Chain in Stagnant Water”, ASME_JSME 4th Joint Fluid Engineering Conference, F E DSM200 3-4 5381, Honolulu, Hawaii, USA, July 2003. M. Ashihara, A. Kitagawa, M. Ishikawa, A. Nakashinchi, Y. Murai, F Yamamoto, “Particle Tracking Velocimetry Measurement of Bubble-Bubble Interaction”, ASME_JSME 4th Joint Fluid Engineering Conference, F E DSM200 3-4 5208, Honolulu, Hawaii, USA, July 2003. T. Munasinghe, “Investigating the Bubble Behavior in Pool Boiling in Microgravity Conditions,” WCE 2008, vol. II, pp. 1366–1371, London, UK, July 2008. C. Maneri, P Vassallo, “Dynamic of Bubble Rising in Finite and Infinite Media” ASME_JSME 4th Joint Fluid Engineering Conference, F E DSM200 3-4 5208, Honolulu, Hawaii, USA, July 2003.
Reference :
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Acknowledgement
Special Thanks to:
NASA -West Virginia Space Grant Consortium at WVU.
West Virginia University, College of Engineering and Mineral Recourse.
Mechanical and Aerospace Engineering Department of WVU.
Dr. John Kuhlman , Dr. Donald Gray, Dr. Majid Jaraiedi , Dr. Arun Ross and Microgravity Research Team.
Zero Gravity Cooperation.
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