Discuss the Constrained Vapor Bubble (CVB) 40mm Fin experiment on the ISS and how it aims to achieve a better understanding of the physics of evaporation and condensation and how they affect cooling processes in microgravity using a remotely controlled microscope and a small cooling devic

Kundan, Akshay

Plawsky, Joel

Wayner, Peter C., Jr.

NASA Technical Reports Server

CVB: The Constrained Vapor Bubble 
40 mm Capillary Experiment on the ISS 
Rensselaer Polytechnic Institute 
 Troy, NY, USA,
ASGRA Annual Meeting 2013
1 
Peter C. Wayner, Jr., Akshay Kundan, & Joel  Plawsky 
https://ntrs.nasa.gov/search.jsp?R=20140010822 2019-08-31T19:38:02+00:00Z
THE  CVB  HEAT  TRANSFER  SYSTEM 
 The CVB is a Constrained Vapor 
Bubble inside a quartz cuvette with a 
working fluid like pentane.   
 Inside 3mm x 3mm ~ 40 mm long. 
 Liquid rises along the sharp corners 
and across the flat surfaces due to 
interfacial forces. 
 Heat source at one end. 
 Inside Radiation and Radiation to the 
surroundings Important  
 Evaporation from the hotter regions; 
condensation in the cooler regions;.  
 Important visual observation through 
the cuvette gives unprecedented 
insight into transport processes. 
 Emissivity = 0.775 for thermal 
radiation frequencies. 
A transparent “heat pipe” – ideal for studying basic fluid 
flow and heat transfer due to interfacial forces inside .  
2 
Micro-gravity Attributes 
  
3 
Interfacial  Forces  Dominate in μg 
Interfacial Curvature (K = 1/R) Gradient is 
Less in  Large (R) Systems [i.e. more flow]; 
Simpler system without natural convection. 
dK
dx
 U

 
 
 
 
 
÷ 
1
R2
=
Capillary Number
R2
 
 
 



  
Use of pressure gradient due to interfacial forces 
that control fluid flow is optimized in μg 
 [ capillarity (K) for all thicknesses +  
disjoining pressure (A/n) for thickness < 100 nm ] 
(Pl  Pv )' =   K +
A
n
 
 
 
 
 
÷ 
'
4 
VISUAL 
Reflectivity  profile  gives 
liquid film thickness profile & 
pressure gradient  in liquid  
Objectives 
• Basic science study of transport processes  
 due to interfacial phenomena.  
  
• Basic engineering study of the CVB 
    extended surface fin (“wickless heat pipe”)  
    for cooling hot surfaces. 
 
• Generic study of phase-change heat transfer processes in 
     a non-isothermal constrained vapor bubble sub-system.   
5 
Recorded Multi-Scale Data 
CVB 
The macroscopic view – 
flow and heat transfer in 
the axial direction  
 
Dimensions ~ mm 
The microscopic view – 
interfacial phenomenon 
at the contact line 
 
Dimensions ~ m 
Axial Corner Curvature Gradient 
6 
• (MACRO) Temperature field from thermocouples gives information 
on the details of heat transfer. 
• (MACRO) Vapor pressure data gives vapor purity and temperature.  
• (MACRO) Surveillance video gives bubble location, stability, boiling. 
• --------------------------------------------------------------------------------------- 
• (MICRO) Liquid film thickness profile from microscopic  reflectivity 
gives local pressure gradient for fluid flow. 
• (MICRO) Transient Reflectivity Profile from video camera on 
microscope gives transient data on microscopic details of pressure 
gradient and fluid flow. 
 
• WHICH  SCALE  DO  WE  ANALYZE  FIRST  ? 
7 
RECORDED  EXTENSIVE  DATA  
8 
Surveillance Camera Images: 
MACROSCOPIC  VIEW 
Isothermal 
1g 
Non-Symmetric  
Isothermal 
g 
Symmetric  Bubble 
  
g 
Heated 
g 
Curvature Gradient  
Liquid at top 
Fluid Flow in 
Meniscus  & 
Condensation 
Heated  
end 
Evaporating  
Meniscus 
Thermo
-couples 
9 
Surveillance Camera Image: 
40 mm higher flux 
 Visual Observations Support Experimental Heat 
Transfer Results Based on the Temperature Profile 
Note: Excess fluid at hot end. 
0.2 W   30 mm Cell – g  at 10 x 
10 
H E A T E R       E N D 
Condensation 
FRINGES  SHOW  THE  DETAILS  OF  
MANY  DIFFERENT  LOCAL  ZONES 
? HOW AND WHERE TO MODEL FIRST  ?  
Evaporation 
Corner meniscus 
Film on flat side surface 
ENGINEERING  SCALE  DATA 
 
(SIMPLE  1D  MODEL  EASIER  TO  
ANALYZE  WHICH  GIVES  OVERALL  
VIEW  OF  TRANSPORT  PROCESSES) 
11 
SIMPLE  ONE  DIMENSIONAL  HEAT  BALANCE 
 
  
 
MEASUREMENTS:  TEMPERATURE  DATA  GIVES OUTSIDE HEAT  TRANSFER  RATE  
PER  UNIT  LENGTH  &  CONDUCTION  GRADIENT IN WALL  
 
1 UNNOWN: qinx , LOCAL INSIDE HEAT TRANSFER RATE PER UNIT  
                               LENGTH INCLUDES RADIATION & PHASE CHANGE  
 12 
qinx = k Ac
d2 T
dx2


	




+ Po  T
4 T
4( )
TEMPERATURE  GIVES  OBVIOUS  CHANGE  IN  AXIAL   CONDUCTION  GRADIENT  
PER  UNIT LENGTH, EXTERNAL  RADIATION  AND INSIDE HEAT TRANSFER 
13 
DRY  CUVETTE  VERSUS  PENTANE  VAPOR  BUBBLE 
14 
Inside heat transfer per unit length for 2 W in g.  Only radiation present on 
inside and outside for the dry case.  Net inside radiation field is thereby known. 
DRY  CUVETTE  VERSUS  PENTANE  VAPOR  BUBBLE 
15 
Conclusions from g 
  
■ Using temperature data, zones in the CVB and local heat transfer 
fluxes were determined. 
■ Phenomena in g are very different –  
■  because of low effective gravity, there is more fluid flow. 
■  because of no natural convection, there is a change in the heat 
transfer profile. 
■ Surface of the CVB runs “hotter” in space due to lack of convective 
cooling.  
■ Macroscopic model shows expected trend – enhanced liquid flow 
and heat transfer coefficient for evaporative heat transfer. 
■ More microscopic models describing the details of the transport 
processes and stability are being evaluated. 
■ Visual  Observation are Essential for Understanding. 
■ Loop Configuration Design Using the CVB Concept is Anticipated. 
 
 16 
 Astronauts Connected CVB and LMM Modules, and Fluids 
Integrated Rack  
 NASA Glenn  Coordinated Study (Fred Kohl, Brian Motil, 
David Chao, Ronald Sicker)  
 Zin Tech Constructed Equipment (Tibor Lorik, Louis 
Chestney, John Eustace, Raymond Margie, John Zoldak)  
 Arya Chatterjee, Akshay Kundan (Graduate Students) 
 Prof. Joel L. Plawsky (CoPI) Co-directed Program 
 NASA  Provided Financial Support 
 Prof. Peter Wayner (PI) Co-directed Program 
 
Acknowledgements 
A Team Effort  
17 
References 
 
• Chatterjee, A, Plawsky, J. L., Wayner, Jr., P. C., Chao, D. F., Sicker, R. J., Lorik, 
T.,Chestney, L.,Eustace, J., Zoldak , J., " Constrained Vapor Bubble Heat 
Pipe Experiment Aboard the International Space Station," AIAA J. 
Thermophysics and Heat Transfer, 27,309-319, (2013). 
 
• “The Constrained Vapor Bubble (CVB) Experiment in the Microgravity 
Environment of the  International Space Station”, A. Chatterjee, J. L. 
Plawsky & P. C. Wayner, Jr. , R. J Sicker, D. F Chao, T. Lorik, L. Chestney, J. 
Eustace, J. Zoldak, 49th AIAA Aerospace Sciences Meeting, Orlando, Fl, 
Jan, 2011.  paper #AIAA-2011-1197 in Proceedings. 
 
• “The Constrained Vapor Bubble Experiment for ISS – Earth’s Gravity 
Results” A. Chatterjee, J. L. Plawsky, P. C. Wayner, Jr., D. F Chao, R. J Sicker, 
T. Lorik, Louis Chestney, J. Eustace, J. Zoldak , AIAA Journal of 
Thermophysics and Heat Transfer, 2010, Vol. 24, #2, 400-410.  
 
18 


CVB: The Constrained Vapor Bubble 40 mm Capillary Experiment on the ISS

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