Phase Transition Of Water Research Articles

Damage Mechanism and Modeling of Concrete in Freeze–Thaw Cycles: A Review

The deterioration of concrete microstructures in freeze–thaw (F–T) cycles is the primary reason for the reduction in the service life of concrete. This paper reviews recent progress in the theory of damage mechanisms and damage models of concrete in F–T cycles. It is a detailed review of the salt-freeze coupling condition, microstructure testing, and models for the evolution of concrete properties that are subjected to F–T damage. Summarized in this paper are the deterioration theory of water phase transition; the mechanism of chloride-F–T and sulfate-F–T damage; the microstructure testing of hydration products, pore structure, microcracks, and interfacial transition zones (ITZ). Furthermore, F–T damage models for the macrostructure are presented. Finally, the issues that are existing in the research and outlook of concrete F–T damage are highlighted and discussed. This paper is helpful in understanding the evolution of F–T damage, and also provides a comprehensive insight into possible future challenges for the sustainable design and specifications of concrete in cold environments.

Experimental study on pore water phase transition in saline soils

Sharp variations of thermophysical properties during the freezing process are caused by phase change of water and salt, which necessitates examining the water and salt transfer as well as deformation of saline soils. Meanwhile, the study on phase change in saline soils can provide the insight conditions for numerical heat-moisture coupling simulation. In order to investigate the principle of phase transformation and crystallization in saline soil with Na2SO4 and NaCl under freezing and freezing-thawing cycles, heat curves of saline soils with different salt concentrations were measured by differential scanning calorimetry (DSC). The temperature of phase transition and supercooling were obtained from the curves. According to the conservation of heat and mass, the proportions of salt crystal, ice crystal and unfrozen water produced during the phase transition were calculated, respectively. The precipitation sequence of salt crystal and ice crystal in saline soils was investigated, and the effect of NaCl on the phase transition of Na2SO4 was analyzed based on the phase change diagram of the salt solution. Finally, the effect of salt type and their concentration on soil structure was analyzed under freezing-thawing cycles, combining with soils' scanning electron microscope (SEM). The results indicated that the rules of supercooling for the soil with NaCl or mixture of Na2SO4 and NaCl were the same, whereby the supercooling diminished as the concentration or soil volume increased. Further, the addition of NaCl can significantly reduce the temperature of phase transition and ice content in sulfate saline soil, while Na2SO4 had little effect on the temperature of soil phase transition. Ice firstly generated in a small portion in soil and salt crystallized with the phase transition occurred for the most of water, and the curve of unfrozen water content in soils shifted toward low-temperature direction as the salt content increased. Phase transition sequence of water and salt will be changed for high salty saline soils under freezing-thawing cycles which has little effect on the precipitation amount of salt crystal in saline soils.

Design and Development of Solar Powered 360degree Automatic Air Cooler

Abstract: Evaporative coolers lower the temperature of air using the principle of evaporative cooling, unlike typical air conditioning systems which use vapor-compression refrigeration or absorption refrigerator. Evaporative cooling is the conversion of liquid water into vapor using the thermal energy in the air, resulting in a lower air temperature. The energy needed to evaporate the water is taken from the air in the form of sensible heat, which affects the temperature of the air, and converted into latent heat, the energy present in the water vapor component of the air, whilst the air remains at a constant enthalpy value. Vapor-compression refrigeration uses evaporative cooling, but the evaporated vapor is within a sealed system, and is then compressed ready to evaporate again, using energy to do so. Simple evaporative coolers water is evaporated into the environment, and not recovered. In an interior space cooling unit, the evaporated water is introduced into the space along with the now-cooled air; in an evaporative tower the evaporated water is carried off in the airflow exhaust. To Develop the Energy efficient, environment friendly direct evaporative air conditioning system having low operating cost suitable for hot and dry regions To Manufacture advanced 360-degree Rotating air cooler which rotates and provide air cooling in all directions. It can be used for domestic as well as Industrial applications. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation). This can cool air using much less energy than refrigeration. In extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants

METHODOLOGICAL APPROACHES TO ESTIMATING A REGIME OF SNOW COVER

This paper gives an analysis of some methods for calculating the amount of melt snow and the regime of snow cover in Brest Region. It is noted that there are many phase transitions of water that influence the initial snow accumulation. Snow water equivalent and its features is proposed to estimate with the use of water balance method. Some design water-balance schemes are provided.

Investigating unfrozen water and its components during freeze–thaw action in loess using a novel NMR technique

AbstractFrost heave and thaw settlement are primarily caused by water migration. Variations in liquid water and its components during freezing and thawing are crucial variables for investigating water migration. Here, a novel soil layer‐scanning method based on magnetic resonance imaging cryogenic soil‐moisture analysis (MRI‐CSMA) was applied to measure dynamic changes of liquid water and its components in nine layers (each 11.1‐mm thick) of four loess samples with different initial water contents (9.2%, 15.7%, 20.0%, and 30.0%) in freezing–thawing experiments under a closed system. The ice–water phase transition and water migration were key factors that controlled the liquid water and its components. During freezing, the liquid water content of each layer (except layer 7) decreased. In the frozen zone (layers 1–6), the liquid water content decreased with decreasing temperature owing to the water–ice phase transition. The lower the temperature, the higher the fraction of water that transitioned to ice. In the unfrozen zone (layers 8–9), parts of the liquid water migrated upward owing to the suction generated at the freezing front. The farther away the freezing front, the smaller the suction and quantity of water migration. During thawing, the liquid water content of each layer increased owing to the ice–water phase transition in the frozen zone and infiltrated down to the unfrozen zone. The contents of the free and adsorbed water exhibited similar change trends to the liquid water content during freezing. However, the change degree of free water was much larger than that of adsorbed water because the phase transition and migration of free water is easier than that of absorbed water. Notably, the liquid water content near the freezing front (layer 7) increased in the early stage of freezing, owing to the combined effect of soil compression and the water–ice phase transition. These results provide a reference for research on water migration in the soil during freezing–thawing and validate the advantage of MRI‐CSMA when characterising water migration in large soil samples.Highlights A novel device (MRI Cryogenic Soil‐Moisture Analyzer) was used. Variations in unfrozen water and its components during freezing were studied. Soil consolidation and pore pressure affect the liquid water change during freezing.

Empirical modeling of pore size distribution for rock materials with its impact on pore water freezing

The phase transition of pore water in porous rock is closely related to the pore size distribution (PSD) based on thermodynamic equilibrium, and the ice formation is further affected by the internal hydraulic pressure and external confinement. This study quantitively assesses the risk of frost damage for rocks with/without surrounding pressures through a thermodynamic approach. First, an empirical PSD model is established and compared with experimental results, which is further adopted to calculate water saturation and ice volume under different humidity and temperature conditions. Then the depression of freezing point is discussed under undrained condition by dividing these rocks into three typical groups in terms of porosity and strength. Moreover, confinement by the high surrounding stress is considered for underground structures to study its influence on the ice formation process. Finally, correlation is found between the lowest bearable temperature and the expression of the porosity and strength of rocks, enabling a convenient assessment of frost damage risk for the rocks.

Soil water potential: A historical perspective and recent breakthroughs

AbstractSoil water potential is a cornerstone in defining the thermodynamic state of soil water required to quantify phenomena such as water phase change, water movement, heat transfer, electric current, chemical transport, and mechanical stress and deformation in the earth's shallow subsurface environment. This potential has historically been conceptualized as free energy stored in a until volume of soil water. Though the concept of soil water potential has been evolving over the past 120 yr, a consensual definition is still lacking, and answers to some fundamental questions remain controversial and elusive. What are the origins and mechanisms for the free energy of soil water? Can the common mathematical expression of soil water potential as superposition of gravitational, osmotic, and matric potentials be used to define water phase transitions in soil? Are these major components of soil water potential independent or coupled? Is pore water pressure always tensile under unsaturated conditions? If so, how can soil water density be as high as 1.7 g cm−3? How do adsorptive soil–water interactions originating from the electromagnetic field around and within soil particles transfer to mechanical pore pressure? In this review, the authors (a) provide critical analysis of historical definitions of soil water potential to identify their strengths, limitations, and flaws; (b) synthesize the origins of electromagnetic energies in soil to clarify the fundamental differences between adsorptive and capillary soil water potential mechanisms; (c) introduce a recently emerging concept of soil matric potential that unifies contributions of adsorption and capillarity to soil water potential; and (d) illustrate the generality and promise of the unified definition of soil water potential for answering some of the fundamental questions that remain elusive to the hydrology, geoengineering, and geoscience communities.

Study of the water dynamics near hydrophilic, nanostructured CuO surfaces by quasielastic and inelastic neutron scattering

We have used quasielastic and inelastic neutron scattering to investigate the structure, dynamics, and phase transitions of water interacting with superhydrophilic CuO surfaces that not only possess a strong affinity for water but also a “grass-like” topography that is rough on both micro- and nanoscales. Here, we report quasielastic neutron scattering (QENS) measurements on two samples differing in water content at five temperatures below 280 K. The QENS spectra show water undergoing two different types of diffusive motion near the CuO surfaces: a “slow” translational diffusion occurring on a nanosecond time scale and a faster rotational motion. Further from the surfaces, there is “fast” translational diffusion comparable in rate to that of bulk supercooled water and the rotational motion occurring in the interfacial water. Analysis of the QENS spectra supports wetting of water to the CuO blades as seen in electron microscopy images. In addition, we observe an anomalous temperature dependence of the QENS spectra on cooling from 270 to 230 K with features consistent with a liquid–liquid phase transition. We suggest that the solvent-like properties of the coexisting bulk-like water in our CuO samples are a significant factor in determining the temperature dependence of the interfacial water’s dynamics. Our results are compared with those obtained from two well-studied substrate classes: (1) silicas that contain ordered cylindrical nanopores but have weaker hydrophilicity and (2) nanoparticles of other transition-metal oxides, such as TiO2, which share the strong hydrophilicity of our samples but lack their porosity.

Demonstration of Escherichia coli Inactivation in Sterile Physiological Saline under High Pressure (HP) Phase Transition Conditions and Analysis of Probable Contribution of HP Metastable Positions Using Model Solutions and Apple Juice.

It was demonstrated that the inactivation of high pressure (HP) treatment on Escherichia coli survival in sterile physiological saline (SPS) was influenced by the treatment conditions: unfrozen, frozen-thawed and fully frozen (phase transition). In order to probe the enhanced phase transition microbial destruction, vibration effects of phase transition position were created and discussed. Test samples were placed in HP chamber for treatment (150/240/330 MPa, no holding time) at room temperature and a special cooling device was used to maintain the phase transition conditions. Results showed that the phase transition from ice I to ice III of frozen SPS could be realized based on the cooling of a 20% sodium chloride solution. HP treatment under fully frozen conditions produced the best lethal effect compared to unfrozen and freeze-thaw samples. Vibration tests were carried out by using model solutions and apple juice to explore the behavior of phase transition. A synchronous and advance phase transition of internal apple juice was realized, respectively, by using pure water and 5% sodium chloride solution as external vibration sources, and the advance phase transitions of external pure water were realized by using 5% sodium chloride solution and 5% glucose solution as internal vibration sources.

Novel Robust, Reusable, Microbial‐Resistant, and Compostable Protein‐Based Cooling Media

AbstractNovel environment‐friendly heat‐storage materials with efficient cooling capacity are in high demand by the food, pharmaceutical, and related industries and supply chains. Better control and prevention of cross‐contamination caused by meltwater from traditional ice have become critical to ensure the safety and quality of food and other commodities. Here is reported a microbial‐resistant, reusable, and compostable novel stationary cooling medium, “Jelly Ice Cubes” (JICs), based on gelatin–menadione sodium bisulfite (MSB) hydrogels (Gel/MSB‐JICs) with cooling efficiency comparable with traditional ice. For the first time, the photo‐crosslinking reactions induced by MSB are proposed and validated theoretically and experimentally. Photo‐tuning is used collectively with rapid‐freeze‐slow‐thaw treatment to construct robust hydrogel frameworks against the functional and structural damages caused by the phase transition of water during repeated uses. Exceptionally stable cooling efficiency and robust mechanical strength are observed across ten application cycles, with stable antimicrobial functions against bacteria, fungi, and yeast. At the end of the lifecycle of JICs, they can be composted or used as a soil treatment to promote plant growth. The novel JICs are competent as promising, safer, and more eco‐friendly substitutes for traditional ice and ice packs.

Giant mechanocaloric effect of nanoconfined water near room temperature

Using water as a refrigerant for innovative cycle-cooling technology is desirable, since water not only is economically and environmentally unrivaled, but also owns a latent heat that is 16-fold that of commercial halohydrocarbon. However, water-based refrigeration has been limited by a phase transition point far from room temperature and intractable volume change upon vaporization. Here, we use a synergy between nanoconfinement and mechanical pressures in regulating the phase transition of water and report a giant mechanocaloric effect in nanoconfined water by thermodynamic analysis and atomistic calculations. The estimated isothermal entropy changes are as high as 1,066 J kg−1 K−1 and adiabatic temperature changes can reach tens of kelvins near room temperature for water confined in slit nanopores. Practical utility of this effect is supported by the robustly high refrigerant performance of water-filled nanoporous carbon matrices. This effect is potentially extendable to other polar liquids and opens new prospects for liquid-state caloric effects.

Effects of sodium nitrate and OPC-GGBS concrete mix composition on phase transition of pore water at subzero temperatures

Lowering the freezing temperature of the mixing water is crucial for concrete works at subzero temperatures. In this study, formation of ice was examined for various pastes and concretes of OPC-GGBS based, while exposed to a constant temperature of −15 °C. Sodium nitrate antifreeze admixture was added as 0, 6, 10, 15, 20, 25, 30 wt% by the total binder amount. The ice formation and its effects on the binder matrix microstructure was studied using differential scanning calorimetry (DSC), ultrasonic pulse velocity (UPV) and Scanning Electron Microscopy – Energy Dispersive Spectrometry (SEM-EDS). Several curing procedures were applied to samples before commencing tests. Results showed that, addition of 25 wt% of the sodium nitrate caused the most extensive delay of the ice growth. Mixes containing less admixture showed an increasing amount of the forming ice which in some cases lead to the development of the false strength. The hydration rate has been the highest for the mix with 25 wt% of the sodium nitrate and tended to be limited at lower additions. The porosity of the hydrated binder matrix tended to be lower for mixes characterized by a lower amount of the forming ice. In general, application of above freezing temperature resulted in resuming of the hydration process that led to densification of the microstructure and strength increase. This trend was more pronounced for mixes having lower amounts of the formed ice.

Phase transition of supercooled water confined in cooperative two-state domain

The question of ‘what is the structure of water?’ has been regarded as one of the major scientific conundrums in condensed-matter physics due to the complex phase behavior and condensed structure of supercooled water. Great effort has been made so far using both theoretical analysis based on various mathematical models and computer simulations such as molecular dynamics and first-principle. However, these theoretical and simulation studies often do not have strong evidences of condensed-matter physics to support. In this study, a cooperative domain model is formulated to describe the dynamic phase transition of supercooled water between supercooled water and amorphous ice, both of which are composed of low- and high-density liquid water. Free volume theory is initially employed to identify the working principle of dynamic phase transition and its connection to glass transition in the supercooled water. Then a cooperative two-state model is developed to characterize the dynamic anomalies of supercooled water, including density, viscosity and self-diffusion coefficient. Finally, the proposed model is verified using the experimental results reported in literature.

Freezing point depression of soil water depending on its non-uniform nature in pore water pressure

The freezing point (FP) of soil water is a vital parameter for hydrothermal coupling simulations in cold regions, and is frequently depressed during soil freezing. Many studies have widely investigated the rules of FP depression affected by the soil type, water content, solute concentration, and external loading; however, few studies have clarified the underlying mechanisms. Water in soils is spatially non-uniform in nature, and the pore water state (PWS) (e.g., pressure) is essential to the FP depression. However, less attention has been paid to the FP depression considering spatially non-uniform nature of soil water. In this study, the FP depression was investigated considering the spatially varied pore water pressure (PWP) and non-uniform nature of soil water. The results showed that the FP depression depends on spatially increased PWP, and the Clausius-Clapeyron equation (CCE) for the phase transition of bulk water can be applied to soil water. These results were verified by two groups of typical experiments of FP with clay soil (external loading Pe = 0, 2, 4, 6, 8, and 10 MPa; gravimetric water content θ = 25, 30, 34, and 38%) and silty clay soil (salt concentration C = 0, 0.5, 1; gravimetric water content θ = 15, 20, 30, 40, and 50%). In addition, the PWP and its components were investigated using the proposed empirical formula.

Quantification the diffusion-induced fractionation of 1H217O isotopologue in air accompanying the process of water evaporation

Advances in laser technology enabling simultaneous analyses of three heavy water isotopologues (1H2H16O, 1H218O and 1H217O) triggered renewed interest in studies of the hydrological cycle using full isotopic composition of water. Such studies require adequate knowledge of equilibrium and kinetic isotope effects accompanying phase transitions of water. Here we report the results of laboratory experiments aimed at quantification of diffusion-induced fractionation of 1H217O isotopologue in air, accompanying the process of water evaporation. Three evaporation experiments have been conducted: (i) evaporation under constant temperature and relative humidity levels, (ii) evaporation under constant temperature and at three different relative humidity levels, and (iii) evaporation under constant relative humidity level and at two different temperatures. Experiment (i) yield the value of diffusive fractionation coefficient of 1H217O isotopologue in air equal 14.64 ± 0.24‰ at 20.4 °C. This value is indistinguishable within the quoted uncertainties from the value of 14.71 ± 0.05‰ derived experimentally for the first time by Barkan and Luz (2007). We confronted these experimental values with the results of state-of-the art quantum–mechanical calculations published recently by Hellmann and Harvey (2020). Experiments (ii) and (iii) yield for the first time the experimental evidence that, contrary to the d-excess, the 17O-excess parameter is largely insensitive to changes in temperature but is sensitive to changes of the relative humidity and this sensitivity increases with the degree of isotope enrichment of the evaporating water body. The linear dependence of kinetic fractionation coefficients of heavy water isotopologues in air on the relative humidity deficit, postulated by the Craig-Gordon isotope model of evaporation process, was confirmed by the results of experiment (ii) for all three isotope systems studied, pointing to correctness of the conceptual framework underlying this widely used model.

Metal-free, in bulk synthesis of highly hydrophilic polyester bearing pyrrolidone pendants and its diblock copolymers with UCST-type phase transition in water

Aliphatic polyesters are readily degradable, highly hydrophobic and lack of functionality. In contrast, polyvinylpyrrolidone (PVP), a vinyl-based polymer, exhibits excellent water solubility owning to its highly hydrophilic pyrrolidone (Py) pendant groups but suffers from degradation issues due to stable C-C bonds in its backbones. Functionalizing polyester with pyrrolidone pendant groups leads to a new type of polymer that is highly hydrophilic and hydrolytically labile at the same time. Well defined functional polyesters can be obtained via controlled ring opening polymerization (ROP) of functional lactone monomers. Functionalization of δ-valerolactone with Py groups is realized by thiol-ene click ligation and subsequent oxidation to afford functional lactone (pyvl). Bulky pendant groups, Py, on lactone rings impede ROP of the functionalized lactones. It is found that strong Brønsted superacid, trifluoromethanesulfonic acid (HOTf), can promote bulk ROP of pyvl at 120 °C and that control of the polymerization can be moderately improved in the presence of diphenylphosphate (DPP) under these conditions. Well defined functional polyesters, poly(pyvl)s, are found to be highly hydrophilic and hydrolytically labile. Surprisingly, its amphiphilic block copolymers such as poly(pyvl)20-b-PCL60 exhibit sharp and concentration-independent UCST type phase transition at around 35 °C in pure water.

Meso- and Macro-Mechanical Analysis of the Frost-Heaving Effect of Void Water on Asphalt Pavement.

In cold regions, many types of structural damages are caused by the frost heaving of asphalt pavements. Hence, it is important to quantitatively determine the frost-heaving effect of asphalt pavement using a mechanical method to control frost-heaving damage. In this study, first, the internal voids of the asphalt mixture were regarded as a single void, and the water phase transition generating the freezing water in the voids was simulated using a simplified hollow sphere model to create a uniform internal pressure. Second, the prediction equation of the equivalent linear expansion coefficient was proposed by taking the phase transition of water in the saturated asphalt mixture voids into account. A step function was used during the phase transition of water to determine the sudden change in the equivalent linear expansion coefficient, heat capacity, density, and thermal conductivity. Finally, the typical cooling conditions were simulated with the water phase transition and the nonwater phase transition. The experimental results showed that the proposed model could accurately simulate the effect of frost heaving. Higher stress and strain were generated on the surface and in the interior of the pavement, and the positions of maximum stress and strain occurred on the pavement surface under the frost-heaving conditions. The compressive strength of the asphalt mixture in a uniaxial compression test is about 4.5–6 MPa with a single freeze–thaw cycle. Furthermore, when frost heaving occurs on the asphalt pavement between 5.8 and 6.5 MPa, the numerical simulation method can be used to calculate the internal stress of the structure, which found that the compressive stress under the frost-heaving condition was the same magnitude as the compressive strength under the freeze–thaw testing condition.

Studies on the identification of frostbitten and frozen meat after defrosting by the spectrophotometric method for determining DNA in muscle tissue extracts

Changes in the state of meat during freezing are determined by the phase transition of water into ice and an increase in the concentration of substances dissolved in the liquid phase. The process of crystal formation leads to a change in the physical characteristics of the meat and may be accompanied by changes in its structural properties. The effect of the proportion of frozen water on the permeability of the membranes of muscle fibers of frostbitten and frozen meat has been established. The ratio of optical densities at wavelengths of 270 nm and 290 nm (R) can be used to judge the thermal state of the meat. It is shown that the value of R after defrosting frozen meat is 2 times higher than for frostbitten meat.

Improvement in Modeling Soil Dielectric Properties During Freeze-Thaw Transitions

Soil freeze-thaw cycles have a profound impact on heat and water fluxes at the land-atmosphere interface and transport in soils. Microwave remote sensing is a widely used technique to detect near-surface soil freeze/thaw states due to significant changes in dielectric properties associated with water phase transitions in soils, where uncertainty remains. This letter proposes a new parameterization scheme for the estimation of unfrozen water content to improve the modeling of soil dielectric properties during freeze-thaw transitions. Predictions from the new model referred to as Zhang-Zhao’s model were compared with dielectric measurements during thawing processes of soil samples collected from Baoding (silty clay soil), Zhangjiakou (loamy sandy soil), and Zhengzhou (clay loam soil) in China. The mean biases of the predictions were 3.25 (4.44 and 2.07 for the thawed value and frozen value, respectively) and 1.54 (2.22 and 0.88 for the thawed value and frozen value, respectively) for the real part and imaginary part, respectively. The model-predicted soil complex relative permittivity (CRP) was highly correlated with measurements, with correlation coefficients ranging from 0.7944 to 0.9865. The normalized root mean square errors of the predictions were 13.72% (real part) and 25.41% (imaginary part).

Discovering formation of ice 0 by low-frequency measurement data

In this work, low-frequency characteristics of wetted nanoporous silicate materials were measured, as well as the specimen’s own low-frequency electric fluctuations at the frequencies of 1…100 Hz. The measurements at low frequencies were conducted at different voltages of the probing signal. A capacity cell was used in making the measurements. In the experiments, at the temperatures below –25…–30 °C, non-linearity of the medium was discovered. The experiments on the study of the specimen’s own electric fluctuations at these temperatures revealed their essential increase. These temperatures are below the point of phase transition of supercooled water to recently discovered ferroelectric ice 0. Based on the measurements made, a conclusion was made regarding formation of this modification of ice in the nanosize pores of the wetted materials under study. Ice 0 is a ferroelectric; therefore, its formation from deeply supercooled water may have a significant impact on the electric parameters of wetted bodies at the temperatures below –23 °C. At the interface of such ice with another dielectric, a thin layer with practically metallic conductivity emerges. Such a layer influences not only the non-linear dependence of dielectric permittivity on the electric field but also increases attenuation of electromagnetic radiation in a medium.