Spatially periodic vapor bubble activity during subcooled pool boiling on 1D aluminum alloy micro-fin arrays

2021 ◽  
Vol 180 ◽  
pp. 121760
Author(s):  
Brendon Doran ◽  
Bin Zhang ◽  
Shayan Davani ◽  
Kojo Asiamah Osafo ◽  
Owen Sutka ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Vapor Bubble ◽  
Pool Boiling ◽  
Spatially Periodic

Self-Propelled Sliding Bubble Motion Induced by Surface Microstructure in Pool Boiling of a Dielectric Fluid Under Microgravity

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Naveenan Thiagarajan ◽  
Sushil H. Bhavnani ◽  
Vinod Narayanan
Keyword(s):  
Vapor Bubble ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Pool Boiling ◽  
Bubble Nucleation ◽  
Radius Of Curvature ◽  
Dielectric Fluid ◽  
Bubble Motion ◽  
Reduced Gravity ◽  
Modification Technique

This paper reports bubble dynamics observed during pool boiling over microstructures with an asymmetric saw-tooth cross section, under reduced gravity. The periodic saw-toothed ratchets etched on a silicon surface include fabricated vapor bubble nucleation sites only on the shallow slope. Reduced gravity pool boiling experiments were conducted aboard a Boeing 727 aircraft carrying out parabolic maneuvers. The fluid used was FC-72, a highly wetting dielectric fluid used as a coolant for electronics. Under microgravity, it was observed that the bubble diameters were six times larger than in terrestrial gravity. Also, self-propelled sliding bubble motion along the surface of the saw teeth was observed in reduced gravity. The velocity of the sliding bubbles across the saw teeth, following lateral departure from the cavities, was measured to be as high as 27.4 mm/s. A model for the sliding bubble motion is proposed by attributing it to the force due to pressure differences that arise in the liquid film between the vapor bubble and the saw-toothed heated surface. The pressure difference is due to difference in the radius of curvature of the interface between the crest and trough of the saw teeth. The surface modification technique, which resulted in the sliding bubble motion, has the potential to alleviate dry-out caused due to stagnant vapor bubbles over heat sources under microgravity when the buoyancy forces are negligible compared to the surface tension forces.

0607 Vapor Bubble Lift-off from a Heated Surface in Subcooled Pool Boiling

2007 ◽  
Vol 2007.3 (0) ◽  
pp. 135-136
Author(s):  
Hiroshi NAGAKURA ◽  
Hayato KUBOTA ◽  
Tomio OKAWA ◽  
Isao KATAOKA
Keyword(s):  
Vapor Bubble ◽  
Heated Surface ◽  
Pool Boiling ◽  
Lift Off

scholarly journals Steady State Vapor Bubble in Pool Boiling

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
An Zou ◽  
Ashish Chanana ◽  
Amit Agrawal ◽  
Peter C. Wayner ◽  
Shalabh C. Maroo
Keyword(s):  
Steady State ◽  
Vapor Bubble ◽  
Pool Boiling

scholarly journals Pool Boiling Heat Transfer from Aluminum Alloy Circular Surface Using Al2O3 and CuO Water Based Nano-fluids

2019 ◽  
Vol 64 (2) ◽  
pp. 283-292
Author(s):  
Adel A. Fahmy ◽  
Ali A. Abdel Aziz
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Aluminum Alloy ◽  
Boiling Heat Transfer ◽  
Volume Fraction ◽  
Heated Surface ◽  
Pool Boiling ◽  
Nano Particles ◽  
Pool Boiling Heat Transfer ◽  
Demineralized Water

The present work aims to study the effect of nano-particles volume fraction of nano-fluid on the heat transfer during pool boiling with different values of heat flux. The concentration ratios by volume in demineralized water are taken as 0.02 %, 0.20 %, 0.40 %, 0.60, and 0.80 % for Al2O3 nano-particles and 0.02 %, 0.06 %, and 0.20 % for CuO nano-particles. Heat transfer coefficients for pool boiling were established experimentally for different values of volume fraction and heat flux. The heating element is made from an aluminum alloy (AL 6061) with a circular smooth surface of 100 mm diameter and 10 mm thickness. The nano-particles porous layer that builds up during boiling is observed by a scanning electron microscope of the heated surface before and after the boiling. The results demonstrate that the heat transfer rate depends on the concentration ratios and heat flux. Using nano-particles decreases the pool boiling heat transfer in comparison with demineralized water. Due to the deposition of nano-particles on the heated surface, lower heat transfer is obtained for a lower bubble departure compared with demineralized water for the small wall superheat.

Sliding Bubble-Pumped Motion Induced by Surface Micro-Structure in Pool Boiling of a Dielectric Fluid Under Reduced Gravity

2014 ◽  
Author(s):  
Naveenan Thiagarajan ◽  
Sushil H. Bhavnani ◽  
Vinod Narayanan
Keyword(s):  
Vapor Bubble ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Pool Boiling ◽  
Bubble Nucleation ◽  
Radius Of Curvature ◽  
Dielectric Fluid ◽  
Bubble Motion ◽  
Reduced Gravity ◽  
Modification Technique

This paper reports bubble dynamics observed during pool boiling over micro-structures with an asymmetric saw-tooth cross-section, under reduced gravity. The periodic saw-toothed ratchets etched on a silicon surface include fabricated vapor bubble nucleation sites only on the shallow slope. Reduced gravity pool boiling experiments were conducted aboard a Boeing 727 aircraft (Zero-g Inc.) carrying out parabolic maneuvers to achieve reduced gravity. The fluid used was FC-72, a highly wetting dielectric fluid used as a coolant for electronics. Under microgravity, it was observed that the bubble diameters were six times larger than in terrestrial gravity. Also, self-propelled sliding bubble motion along the surface of the saw teeth was observed in reduced gravity. The velocity of the sliding bubbles across the saw teeth, following lateral departure from the cavities, was measured to be as high as 27.4 mm/s. A model for the sliding bubble motion is proposed by attributing it to the force due to pressure differences that arise in the liquid film between the vapor bubble and the saw-toothed heated surface. The pressure difference is due to difference in the radius of curvature of the interface between the crest and trough of the saw teeth. The surface modification technique has the potential to alleviate dry out caused due to vapor blanketing of heat sources in microgravity due to negligible buoyancy forces compared to the surface tension forces.

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