characteristics of bubble motion in pool boiling

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

thilanka.munasinghe@mail.wvu.edu.

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The “Key” Terms :

• Pool Boiling

• Microgravity

• Bubble characteristics

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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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