Bubble Formation on the Surface of Laser-Irradiated Nanosized Particles

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Ho-Young Kwak ◽  
Jaekyoon Oh ◽  
Yungpil Yoo ◽  
Shahid Mahmood
Keyword(s):  
Bubble Formation ◽  
Bubble Radius ◽  
Bubble Nucleation ◽  
Heat Diffusion ◽  
Experimental Result ◽  
Liquid Volume ◽  
Expansion Velocity ◽  
Time Curve ◽  
Large Expansion ◽  
Nucleation Model

It is well known that a phase transition from liquid to vapor occurs in the thermal boundary layer adjacent to a nanoparticle that has a high temperature upon irradiation with a high-power laser. In this study, the mechanism by which the evaporated layer adjacent to a laser-irradiated nanoparticle can grow as a bubble was investigated through detailed calculations. The pressure of the evaporated liquid volume due to heat diffusion from the irradiated nanoparticle was estimated using a bubble nucleation model based on molecular interactions. The bubble wall motion was obtained using the Keller-Miksis equation. The density and temperature inside the bubble were obtained by solving the continuity and energy equation for the vapor inside the bubble. The evaporation of water molecules or condensation of water vapor at the vapor–liquid interface and the homogeneous nucleation of vapor were also considered. The calculated bubble radius-time curve for the bubble formed on the surface of a gold particle with a diameter of 9 nm is close to the experimental result. Our study reveals that an appropriate size of the evaporated liquid volume and a large expansion velocity are important parameters for the formation of a transient nanosized bubble. The calculation result suggests that homogeneous condensation of vapor rather than condensation at the interface occurs.

Bubble Formation on the Surface of Laser-Irradiated Nano-Sized Particles

2013 ◽  
Author(s):  
Ho-Young Kwak ◽  
Jaekyoon Oh ◽  
Yungpil Yoo ◽  
Shahid Mahmood
Keyword(s):  
Bubble Formation ◽  
Bubble Radius ◽  
Bubble Nucleation ◽  
Heat Diffusion ◽  
Experimental Result ◽  
Liquid Volume ◽  
Expansion Velocity ◽  
Time Curve ◽  
Large Expansion ◽  
Energy Equations

It is well known that a phase transition from liquid to vapor occurs in the thermal boundary layer adjacent to a nanoparticle that has a high temperature upon irradiation with a high-power laser. In this study, the mechanism by which the evaporated layer adjacent to a laser-irradiated nanoparticle can grow as a bubble was investigated. The pressure of the evaporated liquid volume due to heat diffusion from the irradiated nanoparticle was estimated using a bubble nucleation model based on molecular interactions. The bubble wall motion was obtained using the Keller-Miksis equation. The density and temperature inside the bubble were obtained by solving the continuity and energy equations for the vapor inside the bubble. The evaporation of water molecules or condensation of water vapor at the vapor-liquid interface and the homogeneous nucleation of vapor were also considered. The calculated bubble radius -time curve for the bubble formed on the surface of a gold particle with a diameter of 9 nm is close to the experimental result. Our study reveals that an appropriate size of the evaporated liquid volume and a large expansion velocity are important parameters for the formation of a transient nano-sized bubble. The calculation result suggests that homogeneous condensation of vapor rather than condensation at the interface occurs.

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.

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.

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.

Synchronized High-Speed Video and Infrared Thermometry Study of Bubble Dynamics During Nucleate Boiling of Nanoemulsion

2017 ◽  
Author(s):  
Robert Stephenson ◽  
Jiajun Xu
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Bubble Dynamics ◽  
Nucleate Boiling ◽  
Bubble Nucleation ◽  
Heat Diffusion ◽  
Temperature History ◽  
Pure Ethanol ◽  
High Speed Video ◽  
Significant Difference

In this study, a combination of synchronized high-speed video (HSV) and infrared (IR) thermography was used to characterize the nucleation, growth and detachment of bubbles generated during nucleate boiling inside the nanoemulsion fluid. The Ethanol/Polyalphaolefin nanoemulsion fluid was formed by dispersing ethanol nanodroplets into base fluid Polyalphaolefin, in which these nanodroplets can serve as the pre-seed boiling nuclei. With this unique combination, it allows controlled nucleation, time-resolved temperature distribution data for the boiling surface and direct visualization of the bubble cycle to track bubble nucleation and growth. Data gathered included measurements of bubble growth versus time, as well as 2D temperature history of the heater surface underneath the bubbles. Our findings demonstrate a significant difference of bubble dynamics between the nanoemulsion fluid and pure ethanol, which may also account for the substantial increase in heat transfer coefficient and critical heat flux of nanoemulsion fluid. It is also observed here that the bubbles occurred inside the nanoemulsion fluid appear to be more uniform and two orders-of-magnitude larger in size. While the growth rate of the bubbles inside pure ethanol was found to be heat diffusion controlled at a coefficient around ½, which however, dropped to be around 0.3 for nanoemulsion fluid. Further study on this unique system will help reveal its heat transfer mechanisms.

Electrochemistry of single nanobubbles. Estimating the critical size of bubble-forming nuclei for gas-evolving electrode reactions

2016 ◽  
Vol 193 ◽  
pp. 223-240 ◽  
Author(s):  
Sean R. German ◽  
Martin A. Edwards ◽  
Qianjin Chen ◽  
Yuwen Liu ◽  
Long Luo ◽  
...  
Keyword(s):  
Critical Size ◽  
Bubble Formation ◽  
Water Electrolysis ◽  
Surface Concentration ◽  
Bubble Nucleation ◽  
Critical Surface ◽  
Gas Bubble ◽  
Dissolved Gas ◽  
Stochastic Fluctuations ◽  
Gas Molecules

In this article, we address the fundamental question: “What is the critical size of a single cluster of gas molecules that grows and becomes a stable (or continuously growing) gas bubble during gas evolving reactions?” Electrochemical reactions that produce dissolved gas molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous bubbles. Herein, we demonstrate that electrochemical measurements of the dissolved gas concentration, at the instant prior to nucleation of an individual nanobubble of H2, N2, or O2 at a Pt nanodisk electrode, can be analyzed using classical thermodynamic relationships (Henry's law and the Young–Laplace equation – including non-ideal corrections) to provide an estimate of the size of the gas bubble nucleus that grows into a stable bubble. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (<100 nm radius), and weakly dependent on the nature of the gas. For example, the measured critical surface concentration of H2 of ∼0.23 M at the instant of bubble formation corresponds to a critical H2 nucleus that has a radius of ∼3.6 nm, an internal pressure of ∼350 atm, and contains ∼1700 H2 molecules. The data are consistent with stochastic fluctuations in the density of dissolved gas, at or near the Pt/solution interface, controlling the rate of bubble nucleation. We discuss the growth of the nucleus as a diffusion-limited process and how that process is affected by proximity to an electrode producing ∼1011 gas molecules per second. Our study demonstrates the advantages of studying a single-entity, i.e., an individual nanobubble, in understanding and quantifying complex physicochemical phenomena.

scholarly journals Bubble Nucleation and Growth of Dissolved Gas in Solution Flowing across a Cavitating Nozzle

2015 ◽  
Vol 773-774 ◽  
pp. 304-308 ◽  
Author(s):  
Zhen Hong Ban ◽  
Kok Keong Lau ◽  
Mohd Sharif Azmi
Keyword(s):  
Bubble Dynamics ◽  
Bubbly Flow ◽  
Bubble Formation ◽  
Computational Modelling ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Supersaturated Solution ◽  
Computational Domain ◽  
Dissolved Gas ◽  
Growth Phenomenon

Computational modelling of dissolved gas bubble formation and growth in supersaturated solution is essential for various engineering applications, including flash vaporisation of petroleum crude oil. The common mathematical modelling of bubbly flow only caters for single liquid and its vapour, which is known as cavitation. This work aims to simulate the bubble nucleation and growth of dissolved CO2 in water across a cavitating nozzle. The dynamics of bubble nucleation and growth phenomenon will be predicted based on the hydrodynamics in the computational domain. The complex interrelated bubble dynamics, mass transfer and hydrodynamics was coupled by using Computational Fluid Dynamics (CFD) and bubble nucleation and growth model. Generally, the bubbles nucleate at the throat of the nozzle and grow along with the flow. Therefore, only the region after the throat of the nozzle has bubbles. This approach is expected to be useful for various types of bubbly flow modelling in supersaturated condition.

Fluid Stiction With Mechanical Contact: A Theoretical Model

2016 ◽  
Author(s):  
Rudolf Scheidl ◽  
Hu Zhidong
Keyword(s):  
Evolution Equations ◽  
Outer Boundary ◽  
Bubble Radius ◽  
Growth Dynamics ◽  
Theoretical Work ◽  
Bubble Nucleation ◽  
Mechanical Contact ◽  
Unknown Parameters ◽  
Gap Height ◽  
Bubble Number

Published theoretical work about fluid stiction between two separating plates was so far limited to a finite initial gap. It was shown that pressure and force evolution are well described by fluid film lubrication equations if cavitation is taken into account. The practically important case that plate separation starts from a mechanical contact condition was only studied by experiments. They showed that quite substantial negative pressures can occur in the gap for a very short time and that the peak forces are varying strongly even between consecutive experiments with equal test conditions. In this paper two models are presented which complement the Reynolds equations with dynamical bubble evolution equations. Initial gap height, bubble number density, and initial bubble radius are the three unknown parameters of these models. Initial gap height accounts for surface roughness, the two other parameters refer to the bubble nucleation of the fluid in the small roughness indentations of the gap. A first model employs the Rayleigh-Plesset bubble dynamic model. It requires that the bubbles stay small compared to the gap. Results show that its stiction force dynamics is two orders of magnitude faster than experimentally observed and that the bubble size condition is violated. The second model assumes that bubbles span over the whole gap height and that the flow of the liquid between the bubbles is guided by the Reynolds equation. This model can be brought into reasonable agreement with the experiments. Force variation from experiment to experiment can at least in part be reproduced by a random variation of the initial bubble sizes. The model exhibits a kind of boundary layer behavior close to the outer boundary. This layer represents the interaction zone between bubble growth dynamics, pressure distribution due to viscous flow, and the pressure boundary condition.

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