scholarly journals Homogeneous Freezing of Water Using Microfluidics

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 223
Author(s):  
Mark D. Tarn ◽  
Sebastien N. F. Sikora ◽  
Grace C. E. Porter ◽  
Jung-uk Shim ◽  
Benjamin J. Murray
Keyword(s):  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Recent Theory ◽  
Water Droplets ◽  
Microfluidic Platforms ◽  
High Throughput Method ◽  
Theoretical Predictions ◽  
New Instrumentation ◽  
Controlled Environments ◽  
Homogeneous Freezing

The homogeneous freezing of water is important in the formation of ice in clouds, but there remains a great deal of variability in the representation of the homogeneous freezing of water in the literature. The development of new instrumentation, such as droplet microfluidic platforms, may help to constrain our understanding of the kinetics of homogeneous freezing via the analysis of monodisperse, size-selected water droplets in temporally and spatially controlled environments. Here, we evaluate droplet freezing data obtained using the Lab-on-a-Chip Nucleation by Immersed Particle Instrument (LOC-NIPI), in which droplets are generated and frozen in continuous flow. This high-throughput method was used to analyse over 16,000 water droplets (86 μm diameter) across three experimental runs, generating data with high precision and reproducibility that has largely been unrepresented in the microfluidic literature. Using this data, a new LOC-NIPI parameterisation of the volume nucleation rate coefficient (JV(T)) was determined in the temperature region of −35.1 to −36.9 °C, covering a greater JV(T) compared to most other microfluidic techniques thanks to the number of droplets analysed. Comparison to recent theory suggests inconsistencies in the theoretical representation, further implying that microfluidics could be used to inform on changes to parameterisations. By applying classical nucleation theory (CNT) to our JV(T) data, we have gone a step further than other microfluidic homogeneous freezing examples by calculating the stacking-disordered ice–supercooled water interfacial energy, estimated to be 22.5 ± 0.7 mJ m−2, again finding inconsistencies when compared to theoretical predictions. Further, we briefly review and compile all available microfluidic homogeneous freezing data in the literature, finding that the LOC-NIPI and other microfluidically generated data compare well with commonly used non-microfluidic datasets, but have generally been obtained with greater ease and with higher numbers of monodisperse droplets.

scholarly journals An approximation for homogeneous freezing temperature of water droplets

2015 ◽  
Vol 15 (21) ◽  
pp. 31867-31889
Author(s):  
K.-T. O ◽  
R. Wood
Keyword(s):  
Experimental Studies ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Water Droplets ◽  
Wide Range ◽  
The Mean ◽  
Freezing Temperatures ◽  
Homogeneous Freezing

Abstract. In this work, based on the well-known formulae of classical nucleation theory (CNT), the temperature TNc = 1 at which the mean number of critical embryos inside a droplet is unity is derived and proposed as a new approximation for homogeneous freezing temperature of water droplets. Without consideration of time dependence and stochastic nature of the ice nucleation process, the approximation TNc = 1 is able to reproduce the dependence of homogeneous freezing temperature on drop size and water activity of aqueous drops observed in a wide range of experimental studies. We use the TNc = 1 approximation to argue that the distribution of homogeneous freezing temperatures observed in the experiments may largely be explained by the spread in the size distribution of droplets used in the particular experiment. It thus appears that this approximation is useful for predicting homogeneous freezing temperatures of water droplets in the atmosphere.

scholarly journals Exploring an approximation for the homogeneous freezing temperature of water droplets

2016 ◽  
Vol 16 (11) ◽  
pp. 7239-7249 ◽  
Author(s):  
Kuan-Ting O ◽  
Robert Wood
Keyword(s):  
Water Activity ◽  
Droplet Diameter ◽  
Experimental Studies ◽  
Freezing Temperature ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Water Droplets ◽  
Wide Range ◽  
Freezing Temperatures ◽  
Homogeneous Freezing

Abstract. In this work, based on the well-known formulae of classical nucleation theory (CNT), the temperature TNc = 1 at which the mean number of critical embryos inside a droplet is unity is derived from the Boltzmann distribution function and explored as an approximation for homogeneous freezing temperature of water droplets. Without including the information of the applied cooling rate γcooling and the number of observed droplets Ntotal_droplets in the calculation, the approximation TNc = 1 is able to reproduce the dependence of homogeneous freezing temperature on drop size V and water activity aw of aqueous drops observed in a wide range of experimental studies for droplet diameter > 10 µm and aw > 0.85, suggesting the effect of γcooling and Ntotal_droplets may be secondary compared to the effect of V and aw on homogeneous freezing temperatures in these size and water activity ranges under realistic atmospheric conditions. We use the TNc = 1 approximation to argue that the distribution of homogeneous freezing temperatures observed in the experiments may be partly explained by the spread in the size distribution of droplets used in the particular experiment. It thus appears that the simplicity of this approximation makes it potentially useful for predicting homogeneous freezing temperatures of water droplets in the atmosphere.

Classical nucleation theory of homogeneous freezing of water: thermodynamic and kinetic parameters

2015 ◽  
Vol 17 (8) ◽  
pp. 5514-5537 ◽  
Author(s):  
Luisa Ickes ◽  
André Welti ◽  
Corinna Hoose ◽  
Ulrike Lohmann
Keyword(s):  
Kinetic Parameters ◽  
Thermodynamic Parameters ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Kinetic And Thermodynamic Parameters ◽  
Thermodynamic And Kinetic Parameters ◽  
Homogeneous Freezing

Different formulations of the kinetic and thermodynamic parameters of CNT are evaluated against measured nucleation rates.

scholarly journals Classical nucleation theory of immersion freezing: sensitivity of contact angle schemes to thermodynamic and kinetic parameters

2017 ◽  
Vol 17 (3) ◽  
pp. 1713-1739 ◽  
Author(s):  
Luisa Ickes ◽  
André Welti ◽  
Ulrike Lohmann
Keyword(s):  
Experimental Data ◽  
Contact Angle ◽  
Kinetic Parameters ◽  
Aerosol Particles ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Kinetic And Thermodynamic Parameters ◽  
Immersion Freezing ◽  
Thermodynamic And Kinetic Parameters ◽  
Homogeneous Freezing

Abstract. Heterogeneous ice formation by immersion freezing in mixed-phase clouds can be parameterized in general circulation models (GCMs) by classical nucleation theory (CNT). CNT parameterization schemes describe immersion freezing as a stochastic process, including the properties of insoluble aerosol particles in the droplets. There are different ways to parameterize the properties of aerosol particles (i.e., contact angle schemes), which are compiled and tested in this paper. The goal of this study is to find a parameterization scheme for GCMs to describe immersion freezing with the ability to shift and adjust the slope of the freezing curve compared to homogeneous freezing to match experimental data. We showed in a previous publication that the resulting freezing curves from CNT are very sensitive to unconstrained kinetic and thermodynamic parameters in the case of homogeneous freezing. Here we investigate how sensitive the outcome of a parameter estimation for contact angle schemes from experimental data is to unconstrained kinetic and thermodynamic parameters. We demonstrate that the parameters describing the contact angle schemes can mask the uncertainty in thermodynamic and kinetic parameters. Different CNT formulations are fitted to an extensive immersion freezing dataset consisting of size-selected measurements as a function of temperature and time for different mineral dust types, namely kaolinite, illite, montmorillonite, microcline (K-feldspar), and Arizona test dust. We investigated how accurate different CNT formulations (with estimated fit parameters for different contact angle schemes) reproduce the measured freezing data, especially the time and particle size dependence of the freezing process. The results are compared to a simplified deterministic freezing scheme. In this context, we evaluated which CNT-based parameterization scheme able to represent particle properties is the best choice to describe immersion freezing in a GCM.

scholarly journals Classical nucleation theory of immersion freezing: Sensitivity of contact angle schemes to thermodynamic and kinetic parameters

2016 ◽  
Author(s):  
L. Ickes ◽  
A. Welti ◽  
U. Lohmann
Keyword(s):  
Experimental Data ◽  
Contact Angle ◽  
Kinetic Parameters ◽  
Aerosol Particles ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Kinetic And Thermodynamic Parameters ◽  
Immersion Freezing ◽  
Thermodynamic And Kinetic Parameters ◽  
Homogeneous Freezing

Abstract. Heterogeneous ice formation by immersion freezing in mixed-phase clouds can be parameterized in general circulation models (GCMs) by Classical Nucleation Theory (CNT). CNT parameterization schemes describe freezing as a stochastic process including the properties of insoluble aerosol particles, so called ice nuclei, in the droplets. There are different ways how to describe the properties of aerosol particles (i.e. contact angle schemes), which are compiled and tested in this paper. The goal of this study is to find a parameterization scheme for GCMs to describe immersion freezing with the ability to shift and adjust the slope of the freezing curve compared to homogeneous freezing to match experimental data. The results of using CNT are very sensitive to unconstrained kinetic and thermodynamic parameters in the case of homogeneous freezing leading to uncertainties in calculated nucleation rates Jhom of several orders of magnitude. Here we investigate how sensitive the outcome of a parameter estimation for contact angle schemes from experimental data is to kinetic and thermodynamic parameters. We show that additional free parameter can mask the uncertainty of Jimm due to thermodynamic and kinetic parameters. Different CNT formulations are fitted to an extensive immersion freezing dataset as a function of particle diameter (d), temperature T and time t for different mineral dust types, namely kaolinite, illite, montmorillonite, microcline (K-feldspar) and Arizona test dust. It is investigated how accurate different CNT formulations (with the estimated fit parameters) reproduce the measured freezing curves, especially the time and particle size dependence of the freezing process. The results are compared to a simplified deterministic freezing scheme. It is evaluated in this context which CNT based parameterization scheme to represent particle properties is a good choice to describe immersion freezing in a GCM.

scholarly journals Volume nucleation rates for homogeneous freezing in supercooled water microdroplets: results from a combined experimental and modelling approach

2010 ◽  
Vol 10 (16) ◽  
pp. 7945-7961 ◽  
Author(s):  
M. E. Earle ◽  
T. Kuhn ◽  
A. F. Khalizov ◽  
J. J. Sloan
Keyword(s):  
Numerical Models ◽  
Supercooled Water ◽  
Vapour Phase ◽  
Nucleation Theory ◽  
Rate Coefficients ◽  
Classical Nucleation Theory ◽  
Water Evaporation ◽  
Water Droplets ◽  
Droplet Distribution ◽  
Accommodation Coefficients

Abstract. Temperature-dependent volume nucleation rate coefficients for supercooled water droplets, JV(T), are derived from infrared extinction measurements in a cryogenic laminar aerosol flow tube using a microphysical model. The model inverts water and ice aerosol size distributions retrieved from experimental extinction spectra by considering the evolution of a measured initial droplet distribution via homogeneous nucleation and the exchange of vapour-phase water along a well-defined temperature profile. Experiment and model results are reported for supercooled water droplets with mean radii of 1.0, 1.7, and 2.9 μm. Values of mass accommodation coefficients for evaporation of water droplets and vapour deposition on ice particles are also determined from the model simulations. The coefficient for ice deposition was found to be 0.031 ± 0.001, while that for water evaporation was 0.054 ± 0.012. Results are considered in terms of the applicability of classical nucleation theory to the freezing of micrometre-sized droplets in cirrus clouds, with implications for the parameterization of homogeneous ice nucleation in numerical models.

CONNECTED LENGTH OF FRACTALS (WHY ARE NUCLEATION AND CRITICAL RELAXATION STEPWISE, WHY POLYMERS DESCRIBE n = 0 SPINS)

Fractals ◽  
1993 ◽  
Vol 01 (01) ◽  
pp. 75-83
Author(s):  
Z. ALEXANDROWICZ
Keyword(s):  
Growth Process ◽  
Large Scale ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Recent Theory ◽  
Fractal Cluster ◽  
Single Particles ◽  
Slowing Down ◽  
Opposing Effects ◽  
Typical Length

A stepwise "growth" process, which divides a fractal cluster into branches of sequentially connected particles, helps us to show the following: A reversible growth of a cluster is dominated by an addition of subunits to (or subtraction from) the branches' ends. Main contribution is due to the smallest subunits, viz. single particles. Two consequences follow. First, large scale aggregation and fragmentation may be safely ignored, which supports the classical nucleation theory. Second, relaxation of a cluster is described by the number of back and forth steps needed to traverse the branches' typical length, which supports a recent theory of critical slowing-down. The growth process also helps us to show that bifurcation is due to a fluctuation, modified by a mutual screening, of the branches' ends. For thermal critical clusters, the screening is determined by two opposing effects: Repulsion due to excluded volume, and attraction due to an "induced-growth" of ends by ends. The resultant determines the clusters' deviation from ideality. However, in the case of the uniformly oriented n = 0 vector spins (with no up-or-down option), there can be no fluctuation and clusters grow without bifurcation. This "explains" why linear real polymers describe critical clusters of n = 0 spins.

scholarly journals Volume nucleation rates for homogeneous freezing in supercooled water microdroplets: results from a combined experimental and modelling approach

2009 ◽  
Vol 9 (5) ◽  
pp. 22883-22927 ◽  
Author(s):  
M. E. Earle ◽  
T. Kuhn ◽  
A. F. Khalizov ◽  
J. J. Sloan
Keyword(s):  
Numerical Models ◽  
Supercooled Water ◽  
Vapour Phase ◽  
Nucleation Theory ◽  
Rate Coefficients ◽  
Classical Nucleation Theory ◽  
Water Evaporation ◽  
Water Droplets ◽  
Droplet Distribution ◽  
Accommodation Coefficients

Abstract. Temperature-dependent volume nucleation rate coefficients for supercooled water droplets, JV(T), are derived from infrared extinction measurements in a cryogenic laminar aerosol flow tube using a microphysical model. The model inverts water and ice aerosol size distributions retrieved from experimental extinction spectra by considering the evolution of a measured initial droplet distribution via homogeneous nucleation and the exchange of vapour-phase water along a well-defined temperature profile. Experiment and model results are reported for supercooled water droplets with mode radii of 1.0, 1.7, and 2.9 μm. Values of mass accommodation coefficients for evaporation of water droplets and vapour deposition on ice particles are also determined from the model simulations. The coefficient for ice deposition was found to be approximately 0.031, while that for water evaporation was 0.054. Results are considered in terms of the applicability of classical nucleation theory to the freezing of micrometre-sized droplets in cirrus clouds, with implications for the parameterization of homogeneous ice nucleation in numerical models.

scholarly journals Molecular mechanism for cavitation in water under tension

2016 ◽  
Vol 113 (48) ◽  
pp. 13582-13587 ◽  
Author(s):  
Georg Menzl ◽  
Miguel A. Gonzalez ◽  
Philipp Geiger ◽  
Frédéric Caupin ◽  
José L. F. Abascal ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Bubble Dynamics ◽  
Bubble Formation ◽  
Thermal Fluctuations ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Viscous Forces ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Curvature Dependence

Despite its relevance in biology and engineering, the molecular mechanism driving cavitation in water remains unknown. Using computer simulations, we investigate the structure and dynamics of vapor bubbles emerging from metastable water at negative pressures. We find that in the early stages of cavitation, bubbles are irregularly shaped and become more spherical as they grow. Nevertheless, the free energy of bubble formation can be perfectly reproduced in the framework of classical nucleation theory (CNT) if the curvature dependence of the surface tension is taken into account. Comparison of the observed bubble dynamics to the predictions of the macroscopic Rayleigh–Plesset (RP) equation, augmented with thermal fluctuations, demonstrates that the growth of nanoscale bubbles is governed by viscous forces. Combining the dynamical prefactor determined from the RP equation with CNT based on the Kramers formalism yields an analytical expression for the cavitation rate that reproduces the simulation results very well over a wide range of pressures. Furthermore, our theoretical predictions are in excellent agreement with cavitation rates obtained from inclusion experiments. This suggests that homogeneous nucleation is observed in inclusions, whereas only heterogeneous nucleation on impurities or defects occurs in other experiments.

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