Homogeneous Nucleation Of Vapor Research Articles

Homogeneous vapor nucleation of water in 3 M NaCl solution within a nanopore

Homogeneous vapor nucleation of water in the electrolyte solution within a nanopore at its superheat limit was studied using the bubble nucleation model based on molecular interaction. The wall motion of the bubble that evolved from the evaporated water was obtained using the Keller–Miksis equation and the distribution of temperature inside the bubble was obtained by solving the continuity, momentum and energy equations for the vapor inside the bubble. Heat transfer at the interface was also considered in this study. The nucleation rate of the 3M NaCl solution at 571K is estimated to be approximately 0.15×1028clusters/(m3s). With this value of the nucleation rate, the complete evaporation time of the 50nm radius of the electrolyte solution is approximately 0.60ns. The calculated life time of the bubble that evolved from the evaporated solution, or the time duration for the growth and subsequent collapse of the bubble, is approximately 32ns, which is close agreement with the observed result of 28ns. The bubble reaches its maximum radius of 301nm at 13.2ns after the bubble evolution.

Validity of the Taylor-Sedov Theory for Studying Laser-Induced Phase Explosion and Shock Waves.

Phase explosion is a phase change process that occurs during short pulse laser ablation. Phase explosion is a result of homogeneous nucleation of vapor in the superheated melt and results in a rapid transition from a superheated melt to a mixture of vapor and liquid droplets that expand from the surface. The sudden phase transition results in rapid material removal, and if occurring in an ambient gas, causes a shock wave to propagate away from the surface. Measurements of this shock wave are commonly used with the Taylor-Sedov blast wave theory to estimate shock wave pressure and temperature. At low laser fluences the Mach number of the shock wave can be small, resulting in significant errors in pressure and temperature. The paper will demonstrate conditions for which the more general form of the Rankine-Hugoniot relations for thermo-fluid parameters simplifies to the Taylor-Sedov similarity solutions and when the Taylor-Sedov solutions are applicable. The results are compared to experimental shock wave data from the literature to explain why using the Taylor-Sedov blast wave solutions can result in large errors at low Mach numbers.

Bubble Formation on the Surface of Laser-Irradiated Nanosized Particles

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.

Vapor condensation on nanoparticles in the mixer of a particle size magnifier

The vapor condensation on nanoparticles in a supersaturated gaseous mixture is considered. Supersaturation was created by mixing two flows with different temperatures in a cylindrical mixer at atmospheric pressure. The conditions for mixing were chosen such that the homogeneous nucleation of vapor did not mask the growth of heterogeneous droplets with nanoparticles inside. A mathematical model of the growth of heterogeneous droplets was developed at one-dimensional description of the mixer. Five parameters that affect the performance of the particles size magnifier were identified: temperature of the saturator and the flow with nanoparticles, the number density and initial radius of the nanoparticles, and ratio of flow rates. The results of the simulation are compared with our experimental data.

Homogeneous Nucleation of Vapor at Preferred Sites During Rapid Transient Heating of Liquid in Micropassages

Rapid heating of a liquid at the wall of a micropassage may produce homogeneous nucleation of vapor in the liquid in contact with the surface. In such circumstances, nucleation is generally expected to be most likely to occur in the hottest liquid closest to the surface. It is known, however, that in many cases, the liquid molecules closest to the surface will experience long-range attractive forces to molecules in the solid, with the result that the equation of state for the liquid near the surface will differ from that for the bulk liquid. In micro- and nanopassages, this wall-affected region may be a significant fraction of the passage interior volume. Recent investigations of wall force effects on the liquid indicate that these forces increase the spinodal temperature in the near-surface region. The results of these previous investigations suggest that for heated surfaces with nanoscale roughness, protrusion of bulk fluid into crevices in the surface may make them preferred sites for homogeneous nucleation during rapid heating. A detailed model analysis of the heat transfer in a model conical crevice is developed and used to explore the plausibility and apparent mechanisms of preferred-site homogeneous nucleation. The analysis predicts that protrusion of bulk liquid into a conical cavity does, under some conditions, make the cavity a preferred site for the first occurrence of homogeneous nucleation. The analysis is used to examine the range of conditions under which a crevice will be a preferred site. The implications for nucleation near a solid surface during rapid heating are also explored for circumstances similar to those for bubble nucleation adjacent to heaters in microheater reservoirs in inkjet printer heads.

Thermodynamic analysis of near-wall effects on phase stability and homogeneous nucleation during rapid surface heating

Rapid heating of a liquid by a thin film heater surface may initiate homogeneous nucleation of vapor in the liquid in contact with the surface. In such circumstances, nucleation is generally expected to be most likely in the hottest liquid closest to the surface. It is known, however, that in many cases the liquid molecules closest to the surface will experience long-range attractive forces to molecules in the solid, with the result that the equation of state for the liquid near the surface will differ from that for the bulk liquid. In the investigation summarized here, a statistical thermodynamics analysis was used to derive a modified version of the Redlich–Kwong fluid property model that accounts for attractive forces between the solid surface molecules and liquid molecules in the near-wall region. In this model, the wall–fluid attractive forces are quantified in terms of Hamaker constants. This feature makes it possible to assess the effect of wall–fluid force interactions on the spinodal conditions for a variety of fluid and surface material combinations. The variation of pressure near the wall predicted by this model agrees well with the predictions of a hydrostatic model and molecular dynamics simulations. The results of the thermodynamic model analysis indicate that force interactions are important for a wide variety of fluids only within a few nanometers of the solid surface. The model specifically predicts that these forces increase the spinodal temperature in the near-surface region. The implications of this increase for nucleation near a solid surface during rapid heating are explored for circumstances similar to those in inkjet printer heads. The results of the analysis imply that during rapid transient heating, wall effects can result in homogeneous nucleation occurring first at a location slightly away from the solid surface. The results further suggest that on rough surfaces, wall effects may play a role in making some cavities preferred sites for homogeneous nucleation.

Homogeneous nucleation of vapor by depressurization at constant volume

An analysis has been carried out to determine the thermodynamic requirements for homogeneous nucleation of a vapor bubble when the pressure drops inside a constant-volume container of liquid. This situation can occur in phase change processes when a rigid vessel filled with liquid is cooled. The nucleation equations at constant volume have a somewhat different character from their more familiar constant-pressure counterparts that reflects the change in the boundary conditions for bubble formation. Both the physical and mathematical implications of the new solution are explored in detail, and it is shown to reduce to the well known constant-pressure result in the limiting case of a very large container volume. To illustrate an application of the new equations, some numerical examples have been worked out for homogeneous nucleation of water with various container sizes and initial liquid temperatures. In addition to increasing fundamental understanding of homogeneous nucleation, these results should prove valuable for calculation purposes when vapor nucleation takes place under isochoric rather than isobaric conditions.

Homogeneous nucleation in spatially inhomogeneous systems

Homogeneous nucleation of a vapor in the presence of the loss of clusters by diffusion and thermophoretic drift is investigated. Analytical results are obtained for the cluster size distribution and the rate of nucleation by solving the modified kinetic equation for nucleation. The implications of cluster loss by diffusion and phoretic drift on the onset of the homogeneous nucleation of silicon vapor in the horizontal epitaxial chemical vapor deposition reactor is discussed. The range of conditions under which the loss of subcritical clusters by diffusion and drift becomes important for the interpretation of diffusion cloud chamber experimental data of the onset conditions of the homogeneous nucleation of vapors is also delineated.

Water and Solutions at Negative Pressure: Raman Spectroscopic Study to -80 Megapascals

Microscopic inclusions of aqueous fluids trapped in interstices in quartz and other crystals provide novel systems for the deliberate study of liquids under tension. Liquids under tension should differ in interesting ways from those at ambient pressure or compressed liquids because attractive, rather than repulsive, forces should dominate their behavior. Static tensions in excess of 100 megapascals (~1000 atmospheres) have been obtained reproducibly. Video-recorded observations of the final liquid rupture process, coupled with extrapolations of data at positive pressure, suggest that the homogeneous vapor nucleation point was reached in two of the cases studied. Raman spectra of the fluids at -80 megapascals show that an isothermal volume stretch of -5 percent by volume has only a weak effect on the spectral features and is similar to the effect of isobaric heating.

Two-stage vesiculation in the Cohassett flow of the Grande Ronde Basalt, south-central Washington

The Cohassett flow in south-central Washington is considered a possible host for a nuclear waste repository at the Hanford Site and is being investigated as part of the Basalt Waste Isolation Project. The Cohassett flow of the Grande Ronde basalt contains two vesicular zones separated by 24 m of dense, sparsely vesicular basalt. The vesicular zones represent accumulations of upward-migrating bubbles sequentially frozen-in by the downward passage of the upper solidification front. The separation of the two zones suggests a hiatus in the exsolution of aqueous vapor from the lava. The flow-top vesicular zone formed during and immediately following emplacement of the flow from vapor bubbles nucleated during ascent and eruption, whereas the internal vesicular zone formed after emplacement from bubbles apparently nucleated at the lower solidification front. Homogeneous nucleation of vapor was probably initially driven by large oversaturation pressures in the erupting lava. After emplacement, heterogeneous nucleation of vapor was probably initiated by crystallization in the margins of the flow.

Homogeneous nucleation of vapor from polymer solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHomogeneous nucleation of vapor from polymer solutionsJohn H. Jennings and Stanley MiddlemanCite this: Macromolecules 1985, 18, 11, 2274–2276Publication Date (Print):November 1, 1985Publication History Published online1 May 2002Published inissue 1 November 1985https://doi.org/10.1021/ma00153a037RIGHTS & PERMISSIONSArticle Views96Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (347 KB) Get e-Alerts Get e-Alerts

Homogeneous Vapor Nucleation and Superheat Limits of Liquid Mixtures

Two features distinguish vapor nucleation in multicomponent liquids from the single component case. Both result from the unequal volatilities of the species. One is that the vapor phase may contain several components; the other is that nucleus formation alters the composition of the nearby liquid. These two features are incorporated into the classical theory of homogeneous nucleation to yield a general theory applicable to multicomponent liquids. The theory is applied to binary hydrocarbon mixtures by using an equation of state extrapolated into the metastable region. Superheat limits thus calculated are compared with published experimental results.

A hydrodynamic theory for homogeneous vapor nucleation in a carrier gas

A dynamical theory is constructed for the spontaneous development of a liquid drop out of an homogenous supersaturated vapor in a dense carrier gas. The work required to create intermediate state is estimated macroscopically, as in the classical theory of nucleation, but the dynamical equations are based upon hydrodynamic fluctuation theory. For the classical drop growth model the resulting nucleation rate is very similar to that traditionally assigned. The characterization of the mechanism is a little different from the traditional one, however, and nonequilibrium features of the process are described in greater detail. The vapor condensation process is also contrasted with the liquid– liquid separation process which occurs in binary mixtures.

Statistical mechanics of homogeneous nucleation in vapor

Statistical mechanics of homogeneous nucleation in vapor

Homogeneous nucleation in vapor, Kazumi Nishioka and G. M. Pound, Surface and Colloid Science, Vol.8, ed. E. Matijevic, 297-393, Wiley-Interscience, 1976 : 気相からの均一核生成理論

Homogeneous nucleation in vapor, Kazumi Nishioka and G. M. Pound, Surface and Colloid Science, Vol.8, ed. E. Matijevic, 297-393, Wiley-Interscience, 1976 : 気相からの均一核生成理論

Statistical mechanics of homogeneous nucleation in vapor : By K. Nishioka; Department of Precison Mechanics, Faculty of Engineering, Tokushima University, 770 Tokushima, Japan; and G. M. Pound; Department of Material Sciences and Engienering, Standford University, Stanford, California 94305, U.S.A.

Statistical mechanics of homogeneous nucleation in vapor : By K. Nishioka; Department of Precison Mechanics, Faculty of Engineering, Tokushima University, 770 Tokushima, Japan; and G. M. Pound; Department of Material Sciences and Engienering, Standford University, Stanford, California 94305, U.S.A.