ENHANCEMENT OF BUBBLE FORMATION AND HEAT REMOVAL IN TRANSIENT BOILING

1986 ◽  
Author(s):  
Yoshiyuki Kozawa ◽  
T. Inoue ◽  
Kunito Okuyama
Keyword(s):  
Bubble Formation ◽  
Heat Removal ◽  
Transient Boiling

A Compact Nanostructure Integrated Pool Boiler for Microscale Cooling Applications

2009 ◽  
Author(s):  
Muhsincan S¸es¸en ◽  
Cem Baha Akkartal ◽  
Wisam Khudhayer ◽  
Tansel Karabacak ◽  
Ali Kos¸ar
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
High Efficiency ◽  
Cooling System ◽  
Bubble Formation ◽  
Heat Removal ◽  
Nucleate Boiling ◽  
External Energy ◽  
Excessive Heat ◽  
Aluminum Base

An efficient cooling system consisting of a plate, on which copper nanorods (nanorods of size ∼100nm) are integrated to copper thin film (which is deposited on Silicon substrate), a heater, an Aluminum base, and a pool was developed. Heat is transferred with high efficiency to the liquid within the pool above the base through the plate by boiling heat transfer. Near the boiling temperature of the fluid, vapor bubbles started to form with the existence of wall superheat. Phase change took place near the nanostructured plate, where the bubbles emerged from. Bubble formation and bubble motion inside the pool created an effective heat transfer from the plate surface to the pool. Nucleate boiling took place on the surface of the nanostructured plate helping the heat removal from the system to the liquid above. The heat transfer from nanostructured plate was studied using the experimental setup. The temperatures were recorded from the readings of thermocouples, which were successfully integrated to the system. The surface temperature at boiling inception was 102.1°C without the nanostructured plate while the surface temperature was successfully decreased to near 100°C with the existence of the nanostructured plate. In this study, it was proved that this device could have the potential to be an extremely useful device for small and excessive heat generating devices such as MEMS or Micro-processors. This device does not require any external energy to assist heat removal which is a great advantage compared to its counterparts.

Bubble Formation and Coalescence Under the Influence of Electric Fields

2013 ◽  
Author(s):  
Cila Herman
Keyword(s):  
Electric Fields ◽  
Heated Surface ◽  
Bubble Formation ◽  
Heat Removal ◽  
High Heat ◽  
Gravity Level ◽  
Transfer Rates ◽  
High Heat Transfer ◽  
Industrial Operations ◽  
Bubble Removal

The high heat transfer rates associated with phase-change processes, such as boiling, make them an attractive solution in a range of industrial operations. In terrestrial conditions, the buoyancy force is responsible for bubble removal from the surface, which is essential for heat removal from the surface. Since in space the gravity level is orders of magnitude smaller than on earth, bubbles formed during boiling remain attached at the surface and they also show a tendency to coalesce. As a result, the amount of heat removed from the heated surface is different from terrestrial conditions and it can decrease considerably.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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