Transient Bubble Formation on a Polysilicon Micro Resister

2000 ◽  
Author(s):  
Jr-Hung Tsai ◽  
Liwei Lin
Keyword(s):  
Wall Temperature ◽  
Bubble Formation ◽  
Temperature Drop ◽  
Bubble Nucleation ◽  
Input Current ◽  
Analytical Models ◽  
Nucleation Process ◽  
Heating Wall ◽  
Spherical Bubble ◽  
Heating Source

Abstract Transient bubble formation has been investigated on a polysilicon micro resister of 95μm long, 10μm wide, and 0.5μm thick. The polysilicon micro resister functions as both a heating source and a temperature transducer of thermal bubble nucleation process. At input current of 22 to 30 milliamps, a single spherical bubble is nucleated with a waiting period, when the heating wall temperature drops up to 8°C before a bubble nucleated, of about 1 to 2 seconds depending on the input current. Analytical models are developed to characterize the wall temperature behavior in this micro scale. Substrate warming is found effective to the wall temperature after 0.4 second of heating. Furthermore, evaporation is identified as the major contribution mechanism of the temperature drop before the bubble nucleation. An equivalent heat transfer coefficient is found in the order of 105 W/m2°C with the time constant of 1.25 to 2.5 seconds varying with input current.

Transient Thermal Bubble Formation on Polysilicon Micro-Resisters

2001 ◽  
Vol 124 (2) ◽  
pp. 375-382 ◽  
Author(s):  
Jr-Hung Tsai ◽  
Liwei Lin
Keyword(s):  
Bubble Formation ◽  
Bubble Nucleation ◽  
Heat Diffusion ◽  
Input Current ◽  
Transient Temperature ◽  
Nucleation Behavior ◽  
Middle Range ◽  
Macro Scale ◽  
Micro Bubble ◽  
Transient Thermal

Transient bubble formation experiments are investigated on polysilicon micro-resisters having dimensions of 95 μm in length, 10 μm or 5 μm in width, and 0.5 μm in thickness. Micro resisters act as both resistive heating sources and temperature transducers simultaneously to measure the transient temperature responses beneath the thermal bubbles. The micro bubble nucleation processes can be classified into three groups depending on the levels of the input current. When the input current level is low, no bubble is nucleated. In the middle range of the input current, a single spherical bubble is nucleated with a waiting period up to 2 sec while the wall temperature can drop up to 8°C depending on the magnitude of the input current. After the formation of a thermal bubble, the resister temperature rises and reaches a steady state eventually. The bubble growth rate is found proportional to the square root of time that is similar to the heat diffusion controlled model as proposed in the macro scale boiling experiments. In the group of high input current, a single bubble is nucleated immediately after the current is applied. A first-order model is proposed to characterize the transient bubble nucleation behavior in the micro-scale and compared with experimental measurements.

Stroboscopic Schlieren Study of Bubble Formation during Megasonic Agitation

2012 ◽  
Vol 187 ◽  
pp. 185-189 ◽  
Author(s):  
Marc Hauptmann ◽  
Steven Brems ◽  
Elisabeth Camerotto ◽  
Paul W. Mertens ◽  
Marc M. Heyns ◽  
...  
Keyword(s):  
Bubble Growth ◽  
Bubble Formation ◽  
Bubble Nucleation ◽  
Nucleation Mechanism ◽  
Thermal Dissipation ◽  
Nucleation Process ◽  
Megasonic Cleaning ◽  
Step Process ◽  
Cleaning Agents ◽  
Fundamental Understanding

An important problem in megasonic cleaning is the nucleation process of bubbles, which act as the cleaning agents. A fundamental understanding of this nucleation process will help to optimize the cleaning parameters for future applications to achieve damage free cleaning. In this work, we use quantitative stroboscopic Schlieren imaging to study the interaction of nucleating bubbles with a travelling acoustic wave. The advantage of this method is that it is non-interfering, meaning that it does not disturb the bubble nucleation. It is revealed that nucleation mechanism is a 2 step process, where a regime of slow bubble growth due to rectified diffusion is subsequently followed by a transient cavitation cycle, where bubbles grow explosively. The latter is accompanied by broadband acoustic emission and enhanced thermal dissipation, leading to the occurrence of thermal convection visible in the Schlieren images.

Thermal Modeling of Unlooped and Looped Pulsating Heat Pipes

2001 ◽  
Vol 123 (6) ◽  
pp. 1159-1172 ◽  
Author(s):  
Mohammad B. Shafii ◽  
Amir Faghri ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Heat Pipes ◽  
Analytical Models ◽  
Charge Ratio ◽  
Sensible Heat ◽  
Governing Equations ◽  
Heating Wall ◽  
Heat Mode ◽  
Explicit Finite Difference

Analytical models for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs are presented in this study. The governing equations are solved using an explicit finite difference scheme to predict the behavior of vapor plugs and liquid slugs. The results show that the effect of gravity on the performance of top heat mode unlooped PHP is insignificant. The effects of diameter, charge ratio, and heating wall temperature on the performance of looped and unlooped PHPs are also investigated. The results also show that heat transfer in both looped and unlooped PHPs is due mainly to the exchange of sensible heat.

Bubble Nucleation on Micro Line Heaters

2003 ◽  
Vol 125 (4) ◽  
pp. 687-692 ◽  
Author(s):  
Jung-Yeop Lee ◽  
Hong-Chul Park ◽  
Jung-Yeul Jung ◽  
Ho-Young Kwak
Keyword(s):  
Contact Angle ◽  
Free Surface ◽  
Cluster Model ◽  
Bubble Nucleation ◽  
Nucleation Temperature ◽  
Molecular Cluster ◽  
Resistance Characteristic ◽  
Nucleation Process ◽  
Superheat Limit ◽  
Current Resistance

Nucleation temperatures on micro line heaters were measured precisely by obtaining the I-R (current-resistance) characteristic curves of the heaters. The bubble nucleation temperature on the heater with 3 μm width is higher than the superheat limit, while the temperature on the heater with broader width of 5 μm is considerably less than the superheat limit. The nucleation temperatures were also estimated by using the molecular cluster model for bubble nucleation on the cavity free surface with effect of contact angle. The bubble nucleation process was observed by microscope/35 mm camera unit with a flash light of μs duration.

scholarly journals Euler–Lagrange Modeling of Bubbles Formation in Supersaturated Water

2018 ◽  
Vol 2 (3) ◽  
pp. 39 ◽  
Author(s):  
Alessandro Battistella ◽  
Sander Aelen ◽  
Ivo Roghair ◽  
Martin van Sint Annaland
Keyword(s):  
Phase Transition ◽  
Numerical Models ◽  
Bubble Formation ◽  
Industrial Applications ◽  
Bubble Nucleation ◽  
Initial Growth ◽  
Depletion Effect ◽  
Nucleation Sites ◽  
Scale Modelling ◽  
Spherical Bubbles

Phase transition, and more specifically bubble formation, plays an important role in many industrial applications, where bubbles are formed as a consequence of reaction such as in electrolytic processes or fermentation. Predictive tools, such as numerical models, are thus required to study, design or optimize these processes. This paper aims at providing a meso-scale modelling description of gas–liquid bubbly flows including heterogeneous bubble nucleation using a Discrete Bubble Model (DBM), which tracks each bubble individually and which has been extended to include phase transition. The model is able to initialize gas pockets (as spherical bubbles) representing randomly generated conical nucleation sites, which can host, grow and detach a bubble. To demonstrate its capabilities, the model was used to study the formation of bubbles on a surface as a result of supersaturation. A higher supersaturation results in a faster rate of nucleation, which means more bubbles in the column. A clear depletion effect could be observed during the initial growth of the bubbles, due to insufficient mixing.

A Model of Bubble Nucleation on a Micro Line Heater

1999 ◽  
Vol 121 (1) ◽  
pp. 220-225 ◽  
Author(s):  
S.-D. Oh ◽  
S. S. Seung ◽  
H. Y. Kwak
Keyword(s):  
Bubble Formation ◽  
Three Dimensional ◽  
Bubble Nucleation ◽  
Heat Diffusion ◽  
Nucleation Theory ◽  
Molecular Cluster ◽  
Heater Surface ◽  
Calculation Results ◽  
Critical Bubble ◽  
Superheat Limit

The bubble nucleation mechanism on a cavity-free micro line heater surface was studied by using the molecular cluster model. A finite difference numerical scheme for the three-dimensional transient conduction equation for the liquid was employed to estimate the superheated volume where homogeneous bubble nucleation could occur due to heat diffusion from the heater to the liquid. Calculation results revealed that bubble formation on the heater is possible when the temperature at the hottest point in the heater is greater than the superheat limit of the liquid by 6°C–12°C, which is in agreement with the experimental results. Also it was found that the classical bubble nucleation theory breaks down near the critical point where the radius of the critical bubble is below 100 nm.

Microscopic Activation Phenomena in Heterogeneous Nucleation

2003 ◽  
Author(s):  
J. F. Lu ◽  
X. F. Peng
Keyword(s):  
Liquid Layer ◽  
Solid Surface ◽  
Heterogeneous Nucleation ◽  
Bubble Formation ◽  
Ultrathin Film ◽  
Wall Surface ◽  
Bulk Region ◽  
Heating Wall ◽  
Energy Peak ◽  
Energy Property

The energy property in liquid near the wall was theoretically investigated to understand the effects of wall surface on inception process of nucleation or embryo bubble formation in boiling systems. Analyses indicate that the liquid near heating wall has higher pressure than in bulk region owing to existence of strong attractive forces, and this pressure could maintain a stable liquid microlayer and cause a steady energy peak near the wall. So a vapor embryo is likely to occur beyond the stable microlayer instead of exactly at the solid surface. The stable liquid layer may also be the inception structure of the ultrathin film before nucleation occurs. Fluctuations enhance the phenomenon of energy peak until the nucleation occurs, while energy peak promotes nucleation. Employing the concept of energy peak, the inception phenomena of the microlayer and the formation of embryo bubbles near solid surface were described.

Nucleation Kinetics for Boiling in Microstructures

2005 ◽  
Author(s):  
J. F. Lu ◽  
X. F. Peng ◽  
B. Bourouga
Keyword(s):  
Kinetic Equation ◽  
Dynamic Characteristics ◽  
Nucleation Rate ◽  
Critical Radius ◽  
Momentum Conservation ◽  
Bubble Nucleation ◽  
Nucleation Process ◽  
Nucleation Kinetics ◽  
Bubble Evolution ◽  
Two Stages

Theoretical investigation is conducted to understand the bubble nucleation process in microstructures. The bubble evolution in microstructures is investigated for momentum conservation, and the evolution rate is deeply dependent on the structure. According to different dynamic characteristics in the region close to the critical radius, the nucleation process is divided into two stages. Based on the characteristics of these two stages, a nucleation kinetic equation is modified from classical theory and then is conducted to understand the special bubble nucleation process. The result concludes that the nucleation rate will be deduced if bubble evolution is restrained in microstructures.

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