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.

Homogeneous Bubble Nucleation Predicted by a Molecular Interaction Model

1991 ◽  
Vol 113 (3) ◽  
pp. 714-721 ◽  
Author(s):  
Ho-Young Kwak ◽  
Sangbum Lee
Keyword(s):  
Bubble Formation ◽  
Interaction Model ◽  
Bubble Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Good Prediction ◽  
Evaporation Time ◽  
Modified Model ◽  
Superheat Limit ◽  
Good Agreement

The homogeneous bubble nucleation of various hydrocarbons was estimated by the modified classical nucleation theory. In this modification, the kinetic formalism of the classical theory is retained while the surface energy needed for the bubble formation is calculated from the interaction energy between molecules. With a nucleation rate value of Jnc =1022 nuclei/cm3s, this modified model gives a very good prediction of the superheat limit of liquids. In another test of the model the complete evaporation time of a butane droplet at its superheat limit is compared with experiments and found to be in good agreement.

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.

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.

Bubble Nucleation on Micro Line Heaters

2001 ◽  
Author(s):  
Jung-Yeop Lee ◽  
Hong-Chul Park ◽  
Ho-Young Kwak ◽  
Jin-Seok Jeon
Keyword(s):  
Contact Angle ◽  
Cluster Model ◽  
Bubble Nucleation ◽  
Molecular Cluster ◽  
Resistance Characteristic ◽  
Nucleation Process ◽  
Characteristic Curves ◽  
Superheat Limit ◽  
Current Resistance

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

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.

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.

Absolute Metastable Limit of Liquids and Gas-Liquid Solutions

2009 ◽  
Author(s):  
Ho-Young Kwak ◽  
Hyo-Won Kim ◽  
Ilgon Ko
Keyword(s):  
Tensile Strength ◽  
Cluster Formation ◽  
Bubble Formation ◽  
Nucleation Theory ◽  
Organic Liquids ◽  
Critical Cluster ◽  
Absolute Limit ◽  
Liquid Solutions ◽  
The Absolute ◽  
Superheat Limit

The absolute metastable limit, a one molecule critical cluster formation in the nucleation theory, was obtained by a thermodynamic stability analysis. The tensile strength values obtained for several organic liquids by centrifugal method turned out to be about 50% of the absolute metastable limit, while the tensile strength of water, measured in microscopic inclusions, is close to the absolute metastable limit. On the other hand, the tensile strength values estimated at the superheat limit was about 17% of the absolute limit and the decompression amount for gas bubble formation is about 12% of the absolute limit.

scholarly journals Phase-field modeling of grain evolutions in additive manufacturing from nucleation, growth, to coarsening

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Min Yang ◽  
Lu Wang ◽  
Wentao Yan
Keyword(s):  
Additive Manufacturing ◽  
Phase Field ◽  
Field Model ◽  
Three Dimensional ◽  
Phase Field Model ◽  
Nucleation Theory ◽  
Experimental Result ◽  
Classical Nucleation Theory ◽  
Validation Experiment ◽  
Powder Particles

AbstractA three-dimensional phase-field model is developed to simulate grain evolutions during powder-bed-fusion (PBF) additive manufacturing, while the physically-informed temperature profile is implemented from a thermal-fluid flow model. The phase-field model incorporates a nucleation model based on classical nucleation theory, as well as the initial grain structures of powder particles and substrate. The grain evolutions during the three-layer three-track PBF process are comprehensively reproduced, including grain nucleation and growth in molten pools, epitaxial growth from powder particles, substrate and previous tracks, grain re-melting and re-growth in overlapping zones, and grain coarsening in heat-affected zones. A validation experiment has been carried out, showing that the simulation results are consistent with the experimental results in the molten pool and grain morphologies. Furthermore, the grain refinement by adding nanoparticles is preliminarily reproduced and compared against the experimental result in literature.

scholarly journals Crystal Structure and Computational Study on Methyl-3-Aminothiophene-2-Carboxylate

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 19 ◽  
Author(s):  
Yaping Tao ◽  
Ligang Han ◽  
Andong Sun ◽  
Kexi Sun ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Crystal Packing ◽  
Computational Study ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Dispersion Energy ◽  
Monoclinic Crystal ◽  
Hydrogen Bond Interactions ◽  
Calculation Results ◽  
Reduced Density Gradient ◽  
Reduced Density

Methyl-3-aminothiophene-2-carboxylate (matc) is a key intermediate in organic synthesis, medicine, dyes, and pesticides. Single crystal X-ray diffraction analysis reveals that matc crystallizes in the monoclinic crystal system P21/c space group. Three matc molecules in the symmetric unit are crystallographically different and further linked through the N–H⋯O and N–H⋯N hydrogen bond interactions along with weak C–H⋯S and C–H⋯Cg interactions, which is verified by the three-dimensional Hirshfeld surface, two-dimensional fingerprint plot, and reduced density gradient (RDG) analysis. The interaction energies within crystal packing are visualized through dispersion, electrostatic, and total energies using three-dimensional energy-framework analyses. The dispersion energy dominates in crystal packing. To better understand the properties of matc, electrostatic potential (ESP) and frontier molecular orbitals (FMO) were also calculated and discussed. Experimental and calculation results suggested that amino and carboxyl groups can participate in various inter- and intra-interactions.

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