Homogeneous Nucleation Of Water Research Articles

Understanding the role of polymers on the nucleating behavior of water in dilute supercooled solutions.

Understanding the nucleation behavior of water in dilute polymeric solutions is quintessential for the development of suitable artificial ice recrystallization inhibition (IRI) agents. Although poly(vinyl alcohol) (PVA) is found to be one of the most potent biomimetic IRI agents, the molecular understanding of the nucleation behavior of water in the presence of PVA is still lacking. Here, we use molecular dynamics to elucidate the role of concentration, degree of supercooling, degree of polymerization, and amphiphilicity of PVA and PVA-like polymers on the homogeneous nucleation of water in dilute polymeric solutions using the seeding method. Using classical nucleation theory (CNT), our simulations indicate an increase in the chemical potential difference between ice and melt that favors ice nucleation. However, it also predicts a significant increase in the ice-melt interfacial energy that impedes nucleation. The relative increase in the interfacial energy dominates the increase in the chemical potential difference, which results in a decrease in the nucleation rate of water with an increase in the solute concentration. This study contradicts the previous simulation study that suggested the promotion of homogeneous ice nucleation by PVA and supports the experimental observations of the heterogeneous origins of ice nucleation. Our results also suggest the non-classical origins of ice nucleation in polymeric solutions and the limitation of the CNT in predicting heterogeneous ice nucleation in polymeric solutions.

Homogeneous water nucleation in argon, nitrogen, and nitrous oxide as carrier gases.

Experimental results for homogeneous nucleation of water droplets in the presence of argon, nitrogen, and, for the first time, nitrous oxide as carrier gases are reported. The main objective of the study was to investigate the effects of different carrier gases on the nucleation rate. These gases differ in the number of atoms comprising the molecule, which affects the expansion ratio required to reach the target nucleation temperature. The experiments cover nucleation temperatures from 220 to 260K, nucleation pressures from 40 to 73kPa, supersaturations of 6.5-20, and nucleation rates ranging from about 4 × 105 to 4 × 109cm-3s-1. The new data obtained with a modernized expansion chamber utilizing the nucleation pulse method show good agreement with the available literature data. Another important point of our work is the application of real gas corrections to calculate the nucleation temperature and supersaturation. The results show that the influence of carrier gases on nucleation rate in the investigated pressure range is modest (less than a factor of 7), while without the real gas correction, the apparent effect of carrier gas is significant, with differences as high as a factor of 90.

Formation of ice particles through nucleation in the mesosphere

Abstract. Observations of polar mesospheric clouds have revealed the presence of solid ice particles in the upper mesosphere at high latitudes; however, their formation mechanism remains uncertain. In this study, we investigated the formation process of ice particles through nucleation from small amounts of water vapor at low temperatures. Previous studies that used classical nucleation theory have shown that amorphous solid water particles can nucleate homogeneously at conditions that are present in the mesosphere. However, the rate predictions for water in classical nucleation theory disagree with experimental measurements by several orders of magnitude. We adopted a semi-phenomenological model for the nucleation process, which corrects the evaluation of the molecular cluster formation energy using the second virial coefficient, which agrees with both experiments and molecular dynamics simulations. To calculate the nucleation process, we applied atmospheric conditions for the temperature, pressure, numerical density of dust grains, and cooling rate. The results indicate that homogeneous water nucleation is extremely unlikely to occur in the mesosphere, while heterogeneous nucleation occurs effectively. Dust grains generated by meteor ablation can serve as nuclei for heterogeneous nucleation. We also showed that the ice can form directly in a crystalline state, rather than an amorphous state.

Experimental investigation of homogeneous nucleation of water in various gases using an expansion chamber

Nucleation is an integral part of phase transitions and plays an important role in technology. The control of nucleation in devices such as turbines, rocket and jet engines, wind tunnels, and combustion processes is key to achieving efficient, ecologically sound operation. Our paper presents information about a modernized experimental setup used for homogeneous water nucleation research. The main goal of the study is an analysis of the influence of carrier gas on homogeneous nucleation. The experimental setup based on an expansion chamber has been used for research of homogeneous nucleation over several decades and has undergone various technical improvements. In the Institute of Thermomechanics, the setup was been completely disassembled and cleaned. Pressure transducers, laser, and the data acquisition system have been replaced with modern parts. After that, the chamber was assembled, and thoroughly tested and calibrated. Our investigations were carried with argon and nitrogen as carrier gases in a range of nucleation temperatures 220 – 260 K, pressure range 80-150 kPa, at several concentrations of water vapour. The results thus obtained are consistent with literature data. The findings suggest that this experimental approach is useful for homogeneous water nucleation research.

Critical cluster composition from homogeneous nucleation data: application to water in carbon dioxide\u2013nitrogen carrier gases

Knowledge on critical cluster composition is important for improving the nucleation theory. Thus, homogeneous water nucleation experiments previously carried out in nitrogen and 0%, 5%, 15% and 25% of carbon dioxide ( Campagna et al. 2020a, 2021) are analyzed. The tests were conducted at 240 K and 0.1 MPa, 1 MPa and 2 MPa. The observed nucleation rates are strongly dependent on supersaturation, pressure, temperature and mixture composition. These experimentally found dependencies can be used to derive the composition of critical clusters by means of the nucleation theorem. In this way, a macroscopic quantity, nucleation rate, reveals properties of critical clusters consisting of a few tens of molecules. Two novel methods are presented for the detailed application of the nucleation theorem. The first method extends to mixtures of ,,,,,,,N>2,,,,,, components the approach used in literature for two components. The second method not only applies to N>2 mixtures in a more straightforward manner, but it can also be used for unary as well as for binary and multi-component nucleation cases. To the best of our knowledge, for the first time the critical cluster composition is computed for high pressure nucleation data of a vapor (here water) in mixtures of two carrier gases (here carbon dioxide–nitrogen). After a proper parameterization of the nucleation rate data, both methods consistently lead to the same critical nuclei compositions within the experimental uncertainty. Increasing pressure and carbon dioxide molar fraction at fixed supersaturation leads to a decrease in the water content of the critical cluster, while the adsorbed number of nitrogen and carbon dioxide molecules increases. As a consequence, the surface tension decreases. This outcome explains the observed increase in the nucleation rate with increasing pressure and carbon dioxide molar fraction at constant supersaturation.Graphic abstract

Homogeneous water nucleation in carbon dioxide–nitrogen mixtures: Experimental study on pressure and carrier gas effects

New homogeneous nucleation experiments are presented at 240 K for water in carrier gas mixtures of nitrogen with carbon dioxide molar fractions of 5%, 15%, and 25%. The pulse expansion wave tube is used to test three different pressure conditions, namely, 0.1, 1, and 2 MPa. In addition, a restricted series of nucleation experiments is presented for 25% carbon dioxide mixtures at temperatures of 234 and 236 K at 0.1 MPa. As pressure and carbon dioxide content are increased, the nucleation rate increases accordingly. This behavior is attributed to the reduction in the water surface tension by the adsorption of carrier gas molecules. The new data are compared with theoretical predictions based on the classical nucleation theory and on extrapolations of empirical surface tension data to the supercooled conditions at 240 K. The extrapolation is carried out on the basis of a theoretical adsorption/surface tension model, extended to multi-component mixtures. The theoretical model appears to strongly overestimate the pressure and composition dependence. At relatively low pressures of 0.1 MPa, a reduction in the nucleation rates is found due to an incomplete thermalization of colliding clusters and carrier gas molecules. The observed decrease in the nucleation rate is supported by the theoretical model of Barrett, generalized here for water in multi-component carrier gas mixtures. The temperature dependence of the nucleation rate at 0.1 MPa follows the scaling model proposed by Hale [J. Chem. Phys. 122, 204509 (2005)].

Homogeneous water nucleation: Experimental study on pressure and carrier gas effects.

Homogeneous nucleation of water is investigated in argon and in nitrogen at about 240 K and 0.1 MPa, 1 MPa, and 2 MPa by means of a pulse expansion wave tube. The surface tension reduction at high pressure qualitatively explains the observed enhancement of the nucleation rate of water in argon as well as in nitrogen. The differences in nucleation rates for the two mixtures at high pressure are consistent with the differences in adsorption behavior of the different carrier gas molecules. At low pressure, there is not enough carrier gas available to ensure the growing clusters are adequately thermalized by collisions with carrier gas molecules so that the nucleation rate is lower than under isothermal conditions. This reduction depends on the carrier gas, pressure, and temperature. A qualitative agreement between experiments and theory is found for argon and nitrogen as carrier gases. As expected, the reduction in the nucleation rates is more pronounced at higher temperatures. For helium as the carrier gas, non-isothermal effects appear to be substantially stronger than predicted by theory. The critical cluster sizes are determined experimentally and theoretically according to the Gibbs-Thomson equation, showing a reasonable agreement as documented in the literature. Finally, we propose an empirical correction of the classical nucleation theory for the nucleation rate calculation. The empirical expression is in agreement with the experimental data for the analyzed mixtures (water-helium, water-argon, and water-nitrogen) and thermodynamic conditions (0.06 MPa-2 MPa and 220 K-260 K).

Homogeneous nucleation of nano size H2O bubbles and their growth to micro size in rhyolite melts

Volcanism accompanies transfer of volatiles such as H2O and CO2 from the Earth interior to the atmosphere. The underlying process for transfer of the volatiles is magma degassing. As magma rises toward the Earth surface, the volatiles in silicate melts become supersaturated due to decompression of magma so that nucleation of volatile-bearing bubbles and subsequent growth of the bubble occur. In this study, bubble nucleation rate of water in rhyolite melts above 1000 K, which determines the style of the eruption of the magma, is calculated by using molecular cluster model. Calculation results indicate that the homogeneous nucleation of water in the rhyolite melts is possible when the supersaturation pressure exceeds 110 MPa and the number density of bubbles formed increases as increase in the degree of the supesaturation. Growth of bubble formed from the critical cluster was also calculated and the results were compared with observed bubble sizes. When the bubble number density is greater than 1015/m3, depletion of the concentration of volatiles hinders further growth of bubbles.

Homogeneous nucleation of water in argon. Nucleation rate computation from molecular simulations of TIP4P and TIP4P/2005 water model.

Molecular dynamics (MD) simulations were conducted to study nucleation of water at 350 K in argon using TIP4P and TIP4P/2005 water models. We found that the stability of any cluster, even if large, strongly depends on the energetic interactions with its vicinity, while the stable clusters change their composition almost entirely during nucleation. Using the threshold method, direct nucleation rates are obtained. Our nucleation rates are found to be 1.08×1027 cm-3 s-1 for TIP4P and 2.30×1027 cm-3 s-1 for TIP4P/2005. The latter model prescribes a faster dynamics than the former, with a nucleation rate two times larger due to its higher electrostatic charges. The non-equilibrium water densities derived from simulations and state-of-art equilibrium parameters from Vega and de Miguel [J. Chem. Phys. 126, 154707 (2007)] are used for the classical nucleation theory (CNT) prediction. The CNT overestimates our results for both water models, where TIP4P/2005 shows largest discrepancy. Our results complement earlier data at high nucleation rates and supersaturations in the Hale plot [Phys. Rev. A 33, 4156 (1986)], and are consistent with MD data on the SPC/E and the TIP4P/2005 model.

Numerical Simulation for Dehydration of Natural Gas using Joule Thompson Cooling Effect

In this study, the potential of Joule Thompson cooling effect for natural gas dehydration was studied using numerical simulation method. Population balance model (PBM) was used to simulate the non-equilibrium water condensation process. Meanwhile, empirical nucleation model and diffusion growth model were taken under consideration in order to predict the onset of the water nucleation and the non-equilibrium mass transfer rate. The simulation condition was set at 78% of CO2content,feed pressure of 71bar and temperature of 300K. The Joule Thompson effect has been validated with the experimental data. The non-equilibrium results were then compared with the equilibrium results in order to investigate the pressure drop required for the water nucleation. Results showed that,alarge homogeneous nucleation of water occurred at the pressure drop larger than 30bar. This has resulted in an extremely high condensation rate for the vapor in the natural gas under high pressure drop. Hence, the transition of non-equilibrium to equilibrium can be achieved within 5 milliseconds condensation time, indicating the possibility of Joule Thompson cooling effect in high efficient natural gas dehydration.

The role of water, ice nucleators, and inoculation in insect cold survival

The role of water, ice nucleators, and inoculation in insect cold survival Jan Rozsypal,1,2 1Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Entomology, Ceské Budejovice, Czech Republic; 2Graduate School of Science, Osaka City University, Osaka, Japan Abstract: Over the past century and especially the last few decades a significant progress has been made in our understanding of the mechanisms that underlie the capacity of insects and other ectothermic animals to survive at subzero temperatures. Although we now understand relatively well the complexity of the cold tolerance phenomenon, from the molecular to the ecological level, some aspects remain elusive. This review summarizes current knowledge on the mechanisms of cold tolerance and focuses on the three following issues that remain unsolved in this field: 1) the role of water in preservation of biological structures in organisms that exploit dehydration as a part of their cold survival strategy, 2) the cause of ice nucleation in freeze-intolerant organisms below the temperature range of the activity of ice nucleating proteins and above the temperature of homogeneous nucleation of water, and 3) the capacity of some primarily freeze-intolerant insects to tolerate freezing upon inoculation with ice at high subzero temperatures. Keywords: insect cold tolerance, dehydration, ice nucleators, inoculation

On the effect of pressure and carrier gas on homogeneous water nucleation.

Homogeneous nucleation rates of water droplets were measured at a nucleation temperature close to 240 K in a Pulse-Expansion Wave Tube (PEWT). Several measures were taken to improve the data obtained with the PEWT. For instance, the molar water vapor fraction was determined with three independent techniques. The resulting standard uncertainty of the supersaturation was within 1.8%. Results are given for water nucleation in helium at 100 kPa and at 1000 kPa and in nitrogen at 1000 kPa. Two trends were observed: (i) the values of the nucleation rate of water in helium at 1000 kPa are slightly but significantly higher (factor 3) than its values at 100 kPa and (ii) nucleation rates of water in nitrogen at 1000 kPa are clearly higher (factor 10) than in helium at the same pressure. It is argued that the explanation of the two observed trends is different. For case (i), it is the insufficient thermalization of the growing water clusters in helium at the lowest pressure that has a reducing effect on the nucleation rate, although a full quantitative agreement has not yet been reached. For case (ii), thermal effects being negligible, it is the pressure dependency of the surface tension, much stronger for nitrogen than for helium, that explains the trends observed, although also here a full quantitative agreement has not yet been achieved.

Homogeneous water nucleation and droplet growth in methane and carbon dioxide mixtures at 235 K and 10 bar

Homogeneous nucleation rates and droplet growth rates of water in pure methane and mixtures of methane and carbon dioxide were measured in an expansion wave tube at 235 K and 10 bar. The nucleation rate in pure methane is three orders of magnitude higher than literature nucleation rates of water in low-pressure helium or argon. Addition of carbon dioxide to the carrier gas mixture increases the rates even more. Specifically, rates in a mixture of methane and 3% carbon dioxide are a factor of 10 higher than the rates in pure methane. With 25% carbon dioxide, the rates are four orders of magnitude higher than the rates in pure methane. An application of the nucleation theorem shows that the critical cluster consists of 22 water molecules and 5 methane molecules, for nucleation in pure methane. Growth rates of water droplets were measured in methane and in methane-carbon dioxide mixtures at 243 K and 11.5 bar. At equal temperature, pressure and water vapor fraction, the growth rate of the squared droplet radius is about 20% lower in the mixture with 25% carbon dioxide than in pure methane. The lower growth rate is caused by a smaller diffusion coefficient of water in the mixture with carbon dioxide; the difference of the diffusion coefficients is qualitatively reproduced by the empirical Fuller correlation combined with Blanc's law.

Molecular dynamics simulation for homogeneous nucleation of water and liquid nitrogen in explosive boiling

Molecular dynamics simulations are carried out to study the energy conversion in the homogeneous nucleation processes of the explosive boiling induced by laser heating. Liquid nitrogen and water are investigated as the working fluid. Velocity scaling method is applied to realize the heating process. Three influencing factors, the initial equilibrium temperature of the liquid, the area of the heating zone and the heat quantity are analyzed. It is found that the conversion ratio of energy between heat quantity and potential energy is from 66% to 78% in the process of heating. The influence of the heat quantity on the energy conversion of liquid nitrogen is the same in trend as that of water. The influence of the initial equilibrium temperature and the area of the heating zone on the liquid nitrogen is less than that of water. The difference of energy conversion between water and liquid nitrogen is pretty dramatic, which is because of the hydrogen bond formed by the Coulombic interaction among water molecules.

Homogeneous nucleation rate measurements in supersaturated water vapor II

The homogeneous nucleation of water was studied experimentally in this work using a thermal diffusion cloud chamber; droplets were counted by the photomultiplier method and helium was used as a carrier gas. The nucleation rates range from 3x10(-2) to 3x10(1) cm(-3) s(-1) and six isotherms from 295 to 320 K with step of 5 K are measured. The experimental setup and obtained data are mutually compared to our previous publication [Brus et al., J. Chem. Phys. 129, 174501 (2008)], where the droplets were counted using digital photography and image processing. The molecular content of the critical clusters was estimated from the slopes of experimental data. The measured isothermal dependencies of the nucleation rate of water on the saturation ratio were compared with previously published data of others, several theoretical predictions, and the former nucleation onset data. The aim of the present investigation was to show for the first time that nucleation results can be quantitatively reproduced with two different experimental setups operated in different ways.

Buoyancy-driven convective motion in a thermal diffusion cloud chamber using a water/helium mixture

This work is focused on a 2D numerical simulation of a thermal diffusion cloud chamber (TDCC) operating with water–helium mixture. We particularly address the impact of the stability of the vapor–gas mixture with respect to buoyancy-driven convective motion on homogeneous water nucleation rates. A comparison of our model results with Heist and Reiss results of nucleation of water in helium is first proposed. So, no convective fluxes are assumed within the TDCC and the critical supersaturation of water vapor is in agreement as obtained from numerical predictions. However, the influence of wall heating on the critical supersaturation results is found to be significant as obtained when convective transfers is accounted for within the TDCC and the results deviate significantly from those provided by Heist and Reiss. Their approach may lead large differences in terms of temperature, saturation ratio and nucleation profiles as it oversimplifies heat and mass transfer in TDCC compared to a 2D mass, heat and momentum model.

Computation of maximum rate of water–sulphuric acid nucleation in diesel exhaust

The origin of nucleation mode observed in the diesel engine exhaust is unclear. In this work, the mechanism of simple classical homogeneous water–sulphuric acid nucleation was studied using the parameterization of Vehkamäki, Kulmala, Lehtinen, and Noppel [2003. Modelling binary homogeneous nucleation of water–sulfuric acid vapours: Parameterisation for high temperature emissions. Environmental Science and Technology, 37, 3392–3398]. In the simple model used, condensation and coagulation were taken into account as sink terms in respective equations. The focus of the study was on the total amount of stable clusters formed, which provides an upper limit for nucleation mode number concentration. It was seen that the nucleation can be achieved even with relatively low sulphuric acid concentrations (of the order of 5 × 10 17 m - 3 ). However, the efficiency depends strongly on the cooling and dilution experienced by the exhaust. According to the results obtained, the assumption of homogeneous sulphuric acid–water nucleation depicted by Vehkamäki parameterization gives physically meaningful results with low-sulphur content fuels if the sulphur-to-sulphuric acid conversion factor is close to 100%. Nonetheless, there are published results of nucleation mode in diesel exhaust which cannot be explained by the sulphuric acid–water mechanism.

Homogeneous nucleation of water between 200 and 240 K: New wave tube data and estimation of the Tolman length

We have measured homogeneous nucleation rates of water at 200-240 K in the carrier gas helium, in the range of 10(13) - 10(17) m(-3) s(-1) using an expansion wave tube. The rates agree well with the results of Wolk and Strey [J. Phys. Chem. B 105, 11683 (2001)] in the range of overlap (220-240 K), and are summarized by the empirical fit J = S exp[4.6 + 0.244T-(906.8 - 2.914T)(ln S)(2)], with J the nucleation rate in m(-3) s(-1), S the supersaturation, and T the temperature in K. We find that the supersaturation dependence of both our rates and those of Wolk and Strey is lower than classical theory predicts, and that the critical cluster is smaller than the classical critical size. These deviations are explained in the framework of the Tolman theory for surface tension, and the "Tolman length" is estimated from our experimental results. We find a positive Tolman length that increases with decreasing temperature, from about 0.1 Angstrom at 260 K to (0.6 +/- 0.4) Angstroms at 200 K. We present a nucleation rate expression that takes the Tolman length into account and show that both the supersaturation and temperature dependence are improved, compared to the classical theory.

Binary homogeneous nucleation in water-succinic acid and water-glutaric acid systems.

Binary homogeneous nucleation of water-succinic acid and water-glutaric acid systems have been investigated. The numerical approach was based on the classical nucleation theory. Usually, nucleation is discussed in terms of kinetics, but the thermodynamics involved is undoubtedly equally important. In this paper we studied the above mentioned binary systems giving a quantitative insight into the nucleation process and a detailed consideration of the thermodynamics involved. Both diacids in study are in solid state at room temperature. They behave in environment according to their liquid state properties because of the absence of crystalline lattice energies, and therefore their subcooled liquid state thermodynamics have to be considered. The lack of consistent thermodynamic data for pure organic components and their aqueous solutions represent a high source of uncertainty. However, the present simulations indicate that in atmospheric conditions these binary systems will not form new particles.

Homogeneous Nucleation of Water in Mesoporous Zeolite Cavities

In this paper, we show that water inside mesoporous cavities in zeolites can be supercooled to ca. -40 degrees C at which point homogeneous nucleation of the water takes place. The fundamental phenomena observed here are similar to those reported earlier in for example emulsion droplets or droplets in the vapor phase. However, as these zeolite materials are widely available, they may provide an easily accessible source for studies of supercooled liquids in confinements. Next to this, it is now possible to discriminate with thermoporometry between mesoporous cavities inside the zeolite crystals, in which homogeneous nucleation takes place, and mesopores that are connected to the external surface in which heterogeneous nucleation takes place.