Water-ice Phase Transition Research Articles

The coefficient smoothing method application to the problem of gas pipeline glaciation

In northern seas the gas temperature in the pipeline may be lower than the water-ice phase transition temperature, so the glaciation process must be considered. The coefficient smoothing method for the problem of glaciation of the cylinder immersed in seawater is considered. The model of glaciation process is presented as a problem for the linear heat equation in domain with unknown moving boundary. The method of solution is based on the transition to the Dirichlet problem for the nonlinear two-dimensional heat equation in domain with fixed boundaries. The splitting method is applied to the solution of the problem for two-dimensional heat equation. Two approximations for the Dirac delta function are proposed. Calculation of uniform glaciation process was carried out with the using of nonlinear implicit finite-difference schemes. Time moments of the glaciation for different spatial layers are obtained. Results of calculations are compared with the results obtained by the front-tracking method.

Formation of the impermeable layer in the process of methane hydrate dissociation in porous media

The problem of decomposition of methane hydrate coexisting with water in a highpermeability reservoir is considered. The asymptotic solution is obtained for the decomposition regime in the negative temperature domain. Energy estimates presented show that an impermeable layer saturated with a hydrate-icemixture can be formed in reservoirs with initial positive temperature. The mathematical model of the process of hydrate decomposition is formulated under the assumption on the presence of such a layer in a high-permeability reservoir. In this case the problem is reduced to a purely thermal problem with two unknown moving boundaries. The water-ice phase transition takes place on the leading boundary, while hydrate dissociates at negative temperatures on the slower boundary. The conditions of existence of the layer saturated with a hydrate-ice mixture which is implemented in reservoirs with the high hydrate content are investigated.

Electrophysical properties of nanoporous cerium dioxide\u2013water system

The impedance of nanoporous cerium dioxide with adsorbed water is investigated in the frequency range 103–104 Hz at temperatures near the water–ice phase transition. Here we show that the manifestation of impedance peculiarities at phase transition is caused by the dielectric constant of the matrix.

The water cycle in the general circulation model of the martian atmosphere

Within the numerical general-circulation model of the Martian atmosphere MAOAM (Martian Atmosphere: Observation and Modeling), we have developed the water cycle block, which is an essential component of modern general circulation models of the Martian atmosphere. The MAOAM model has a spectral dynamic core and successfully predicts the temperature regime on Mars through the use of physical parameterizations typical of both terrestrial and Martian models. We have achieved stable computation for three Martian years, while maintaining a conservative advection scheme taking into account the water–ice phase transitions, water exchange between the atmosphere and surface, and corrections for the vertical velocities of ice particles due to sedimentation. The studies show a strong dependence of the amount of water that is actively involved in the water cycle on the initial data, model temperatures, and the mechanism of water exchange between the atmosphere and the surface. The general pattern and seasonal asymmetry of the water cycle depends on the size of ice particles, the albedo, and the thermal inertia of the planet’s surface. One of the modeling tasks, which results from a comparison of the model data with those of the TES experiment on board Mars Global Surveyor, is the increase in the total mass of water vapor in the model in the aphelion season and decrease in the mass of water ice clouds at the poles. The surface evaporation scheme, which takes into account the turbulent rise of water vapor, on the one hand, leads to the most complete evaporation of ice from the surface in the summer season in the northern hemisphere and, on the other hand, supersaturates the atmosphere with ice due to the vigorous evaporation, which leads to worse consistency between the amount of the precipitated atmospheric ice and the experimental data. The full evaporation of ice from the surface increases the model sensitivity to the size of the polar cap; therefore, the increase in the latter leads to better results. The use of a more accurate dust scenario changes the model temperatures, which also strongly affects the water cycle.

Role of water vapor desublimation in the adhesion of an iced droplet to a superhydrophobic surface.

The study of the adhesion of solid and liquid aqueous phases to superhydrophobic surfaces has become an attractive topic for researchers in various fields as a vital step in the design of icephobic coatings. The analysis of the available results shows that the experimentally measured values of adhesion strength for superhydrophobic substrates, which in some cases are quite small, are still essentially higher than might be expected from the portion of the actual wetted area. In this study we have considered the peculiarities of the three-phase contact zone between sessile supercooled water or ice droplets and a superhydrophobic coating at negative temperatures (below 0 °C) and during the water-ice phase transition. Two types of superhydrophobic coatings with very different textures were used to analyze the evolution of shape parameters of a sessile water droplet during droplet cooling and freezing. It was shown that the evolution of the contact angle and droplet contact diameter of a water droplet deposited on a superhydrophobic surface does not undergo essential changes when the droplet is cooled simultaneously with the substrate and the surrounding environment, and the humidity is maintained close to 100% during the cooling process. However, the phase transition from supercooled water to ice droplets leads to the growth of a metastable iced meniscus and a frost halo in the vicinity of the three-phase contact zone. The meniscus effectively increases the area of adhesive contact between the droplet and the substrate. This phenomenon is intrinsically related to the release of the heat of crystallization and is responsible for the enhancement of adhesion to a superhydrophobic substrate upon droplet transition from supercooled water to ice. At the same time, it was shown that the metastable state of the above meniscus leads to its spontaneous sublimation during exposure at negative temperatures.

A scale down process for the development of large volume cryopreservation

The process of ice formation and propagation during cryopreservation impacts on the post-thaw outcome for a sample. Two processes, either network solidification or progressive solidification, can dominate the water–ice phase transition with network solidification typically present in small sample cryo-straws or cryo-vials. Progressive solidification is more often observed in larger volumes or environmental freezing. These different ice phase progressions could have a significant impact on cryopreservation in scale-up and larger volume cryo-banking protocols necessitating their study when considering cell therapy applications.This study determines the impact of these different processes on alginate encapsulated liver spheroids (ELS) as a model system during cryopreservation, and develops a method to replicate these differences in an economical manner.It was found in the current studies that progressive solidification resulted in fewer, but proportionally more viable cells 24h post-thaw compared with network solidification. The differences between the groups diminished at later time points post-thaw as cells recovered the ability to undertake cell division, with no statistically significant differences seen by either 48h or 72h in recovery cultures.Thus progressive solidification itself should not prove a significant hurdle in the search for successful cryopreservation in large volumes. However, some small but significant differences were noted in total viable cell recoveries and functional assessments between samples cooled with either progressive or network solidification, and these require further investigation.

A mathematical model of channel deformations in permafrost zone rivers

A mathematical model is presented, allowing the calculation of channel deformations of permafrost zone rivers caused by thermo-erosional niching under the effect of waves of different origin under the conditions of growing ambient temperature. The model is based on equations of transient fluid motion in two-dimensional formulation, Stefan equation for determining the displacement of water-ice phase transition interface, and mass conservation equations for transported sediments (deformation equations). The model was tested against a particular case of steady flow based on data of a laboratory experiment. Numerical experiments revealed the key factors of the process and allowed the impact of waves with different duration and intensity (spring floods and releases from engineering structures) on river channel to be analyzed.

Detection of water–ice phase transition based on Raman spectrum

A simplified dimensionless method was constructed to characterize the phase transition between water and ice based on Raman spectrum (RS) without contact testing samples. This method reduces the requirement of the spectrum intensity, simplifies the complex mathematical analysis and improves the resolution of detection which only depends on the relative intensity of RS. The current work establishes an important tool for accurate characterization of RS so that it could better interpret various phase transition mechanisms of water and aqueous solutions. Copyright © 2013 John Wiley & Sons, Ltd.

Well-posedness of an extended model for water-ice phase transitions

We propose an improvedmodel explaining the occurrence of high stresses due to thedifference in specific volumes during phase transitions betweenwater and ice. The unknowns of the resulting evolution problem are the absolute temperature,the volume increment, and the liquid fraction. The main novelty here consistsin including the dependence of the specific heat and of the speed of soundupon the phase. These additional nonlinearities bringnew mathematical difficulties which require new estimation techniques based onMoser iteration. We establish the existence of a global solution tothe corresponding initial-boundary value problem, as well as lower andupper bounds for the absolute temperature. Assuming constant heat conductivity,we also prove uniqueness and continuous data dependence of the solution.

Regular network model for the sea ice-albedo feedback in the Arctic

The Arctic Ocean and sea ice form a feedback system that plays an important role in the global climate. The complexity of highly parameterized global circulation (climate) models makes it very difficult to assess feedback processes in climate without the concurrent use of simple models where the physics is understood. We introduce a two-dimensional energy-based regular network model to investigate feedback processes in an Arctic ice-ocean layer. The model includes the nonlinear aspect of the ice-water phase transition, a nonlinear diffusive energy transport within a heterogeneous ice-ocean lattice, and spatiotemporal atmospheric and oceanic forcing at the surfaces. First results for a horizontally homogeneous ice-ocean layer show bistability and related hysteresis between perennial ice and perennial open water for varying atmospheric heat influx. Seasonal ice cover exists as a transient phenomenon. We also find that ocean heat fluxes are more efficient than atmospheric heat fluxes to melt Arctic sea ice.

Optimal control of ice formation in living cells during freezing

A mathematical model of ice formation in living cells during freezing is considered. Application of appropriate averaging techniques to partial differential equations describing the dynamics of water–ice phase transitions reduces spatially distributed relations to several ordinary differential equations with control parameters and uncertainties. Such equations together with an objective functional which expresses the difference between the amount of ice in the extracellular and intracellular liquids are treated as a differential game where the aim of the control is to maximize the objective functional and the aim of the disturbance is opposite. A stable finite-difference scheme for computing the value function is developed. Based on the computed value function, optimal controls are designed to produce cooling protocols ensuring simultaneous freezing inside and outside of living cells. Such a regime balances the pressures inside and outside of cells, which may prevent cells from injuring.

Water–ice phase transition probed by Raman spectroscopy

AbstractRaman spectroscopy was used to study the liquid–solid water phase transition. Special attention was devoted to the OHstretching band of the Raman spectrum, which shows monotonous changes in the temperature range between 10 and − 15 °C. The interpretation of this spectral change, as well as a careful analysis of its integrated scattered intensity, led to a spectral marker that allows the determination of the water phase (liquid or solid), and the efficient identification of the liquid–solid phase transition itself. Copyright © 2011 John Wiley & Sons, Ltd.

On the stability of clathrate hydrates in comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen

Context. For several years, Jupiter-family comets have been the targets of spacecraft missions whose aims are to determine the comets' composition, structure, and physical properties. The Rosetta mission is currently flying towards comet 67P/Churyumov Gerasimenko for a rendezvous in August 2014 and comet 46P/Wirtanen is considered for a rendezvous in 2021 with the PriME (Primitive Material Explorer) mission, which is currently proposed to NASA. Aims. Here we investigate the stability conditions of clathrate hydrates within the comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen by considering an initial mixture of amorphous H 2 O with CO, CO 2 , CH 4 , and H 2 S in the nuclei. Methods. We use a one-dimensional nucleus model, which considers an initially homogeneous sphere composed of a predefined porous mixture of ices and dust in specified proportions and describes heat transmission, gas diffusion, sublimation/recondensation of volatiles within the nucleus, water ice phase transition, dust release, and mantle formation. Results. We show that stability conditions of multiple guest clathrates are permanently reached in the subsurface of both comets, and in a broader manner in the subsurface of all short period comets. The thickness of the stability zone of the clathrate slightly oscillates with time as a function of the heliocentric distance, but never vanishes. When comets approach perihelion, our calculations suggest that clathrate layers, which are located closer to the nucleus surface, may destabilize before amorphous ice is tranformed into crystalline ice.

Estimate of Phase Transition Water Content in Freeze–Thaw Process Using Microwave Radiometer

Ground surface freeze-thaw cycles caused by changes in solar radiation have a great impact on soil-air water heat exchanges due to the phase transition of pore water. This influence should not be ignored in the land surface process and global environment change studies because of its large extent and the rapid changes in daily and seasonal frozen ground. The key index for evaluating the influence intensity is the content of water-ice phase transition in soil pores at the ground surface. In this paper, a data set was generated by observing field experiments and physical model simulations based on the configuration of the Advanced Microwave Scanning Radiometer-EOS (AMSR-E). The results showed that microwave radiation from freezing/thawing soil has an obvious correlation to the phase transition process of soil water. A large change in soil surface emissivity was shown after the freezing of soil. The magnitude of the difference in emissivity change is strongly related to the amount of water-ice phase transition. It can be shown that the higher the phase transition water content (PTWC), the greater the emissivity difference, and the higher the frequency, the smaller the emissivity difference. Based on an analysis of a large amount of random simulation data, an interesting characteristic was found, in that the emissivity difference in vertical polarization at each frequency is nearly proportional to the phase transition water content. Thus, a ratio index called Quasi-emissivity (Qe) was developed to eliminate temperature effects during retrieval. Using these clear rules, a physical statistical algorithm was put forth to estimate the phase transition water content. Finally, the inferred results by ground-based radiometer observation were compared with the ground truth. A satisfying agreement was achieved with a root mean square error of 0.0265 (v/v). This indicated that the microwave radiometer has a great potential in the measurement of PTWC.

Phase diagram of H2O: Thermodynamic functions of the phase transitions of high-pressure ices

The analysis of the internal structure of the ice satellites of the Solar System’s giant planets, Jupiter and Saturn, and the estimation of the composition of other water-containing cosmic bodies require thermodynamic information on the phase transformations in the water-ice system. This work presents experimental and theoretical data on the studies of the phase diagram of water (H2O) and the thermodynamic properties of water ices that were generalized, analyzed, and systematized. A brief description of the equations of state for different modifications of high-pressure ices that are most frequently used in thermodynamic calculations is presented. Based on the mathematical treatment of available experimental data for phase equilibria in the water-ice system, the boundaries of the phase transitions between crystal ices I, II, III, V, VI, VII, VIII, and X and liquid water are constructed; in addition, the thermal dependences of the thermodynamic functions (changes in enthalpy, entropy, and volume) of most water-ice phase transitions are obtained.

Ultrafast IR spectroscopy of ice–water phase transition

Superheating and bulk melting of neat H 2O ice are studied using 2-color IR spectroscopy with sub-picosecond pulses. The data are compared with similar experiments in 15 M HDO in D 2O. After calibration of our spectroscopic thermometer a maximum superheating of the solid phase up to 330 ± 10 K is observed after ultrafast temperature jumps. For energy depositions beyond the limit of superheating a strong evidence for partial melting in two steps is observed. The ultrafast thermal melting leads to formation of water clusters in the excited ice lattice and is followed by secondary melting at the generated phase boundaries. The latter process is found to consume energy amounts in agreement with the latent heat of melting and is accompanied by an accelerated temperature and pressure decrease of the residual ice component. The bottleneck of the initial melting process seems to be the thermalization time of the hydrogen-bonded network of 7.0 ± 1 ps.

10.1007/s11455-008-3020-4

Phase increments of the coefficient of microwave reflection from the air-ice interface have been measured at a frequency of 13.8 GHz at temperatures in the vicinity of the ice-water phase transition. It is established that the phase of the reflection coefficient exhibits variations within several dozen degrees upon the appearance of the first signs of ice melting. This phenomenon has to be taken into account in interpreting the results of phase-sensitive radar probing for glacial objects.

Numerical simulation on gas production from a hydrate reservoir underlain by a free gas zone

Physical and mathematical models of gas production by depressurization from a hydrate reservoir underlain by a free gas zone are established. The mathematical model can interpret the effects of the flow of multiphase fluids, the process of hydrate dissociation, ice-water phase transition, the variation of permeability, the convection and conduction on hydrate dissociation and gas and water production. The evolutions of temperature, pressure, and saturations in the hydrate and free gas zones are elucidated during gas production. The variation of some parameters, such as gas and water rates, with time is presented. The results show that the overlying hydrate zone can supply a certain amount of gas to improve the output of a production well and evidently prolong the lifespan of a gas reservoir.

Phase variations of the microwave reflection coefficient for ice near the phase transition temperature

Phase increments of the coefficient of microwave reflection from the air-ice interface have been measured at a frequency of 13.8 GHz at temperatures in the vicinity of the ice-water phase transition. It is established that the phase of the reflection coefficient exhibits variations within several dozen degrees upon the appearance of the first signs of ice melting. This phenomenon has to be taken into account in interpreting the results of phase-sensitive radar probing for glacial objects.

Bulk Melting of Ice at the Limit of Superheating

The ice-water phase transition after an ultrafast temperature jump is studied in HDO:D2O (15 M) ice with use of 2-color IR spectroscopy. The OH-stretching vibration is applied for rapid heating of the sample and for fast and sensitive probing of local temperature and structure. For energy depositions beyond the limit of superheating (330 +/- 10 K) partial melting in two steps is observed and assigned to (i) catastrophic melting within the thermalization time of the excited ice lattice of 5 +/- 2 ps and (ii) secondary melting with a time constant of 33 +/- 5 ps that is assigned to interfacial melting at the generated phase boundaries. The latter process is found to consume energy amounts in agreement with the latent heat of melting and is accompanied by an accelerated temperature and pressure decrease of the residual ice component.