Freezing Process Of Water Research Articles

Numerical and experimental investigations on the effect of skeleton shapes and heat transfer directions on water freezing in porous media

Incorporating porous skeletons into PCMs is an effective strategy for enhancing their thermal properties. However, this approach increases the complexity of the heat transfer process and poses a challenge to accurate modeling. This study investigates the water freezing process in porous skeletons with various shapes and heat transfer directions through experiments and numerical simulations. The model employs the hybrid finite element method with mesh adaptation to optimize numerical solutions. The experimental and simulation results are in good agreement, which validates the accuracy of this model. The study aims to reveal the evolution mechanisms of the phase interface, temperature field, and freezing rate of water in various porous skeletons, enhancing the theoretical foundation and offering insights for practical applications. Results show that the square steel skeleton exhibits the highest freezing rate among the tested skeleton shapes, while the rhombus resin skeleton demonstrates the slowest. Furthermore, the square skeleton shows the smallest interface deflection before and after the pores, while the rhombus skeleton presents the largest. Additionally, vertical heat transfer from bottom to top increases the freezing rate by 38.97% compared to horizontal heat transfer from left to right.

Effect of contact thermal resistance and skeleton thermodynamic properties on solid-liquid phase change heat transfer in porous media: A simulation study

Phase change materials (PCMs) have the potential for heat storage and release, but low thermal conductivity limits their wide application in thermal systems. This work proposes a mathematical model to simulate the freezing process of water in porous media. Unlike traditional methods that solve for two temperatures in different materials, the hybrid finite element method computes a single temperature satisfying the jump on the interface. The effect of contact thermal resistance and skeleton parameters on solid-liquid phase change heat transfer was investigated. This model was validated by experiments in reference. Results show that increased contact thermal resistance decreases temperature gradient, phase interface deflection and freezing rate. Specifically, with contact thermal resistance of 0.0001 K/W, 0.0005 K/W, and 0.001 K/W, freezing rates decrease by 36.4 %, 52.35 %, and 54.14 %, respectively, compared to the case without resistance. Although the contact thermal resistance reduced the temperature gradient, it stabilized the phase change process. Moreover, higher thermal conductivity of the skeleton enhances the freezing rate. However, after a certain value is reached, the rate increases only marginally. Skeletons with lower density and specific heat capacity are favorable to enhancing phase change heat transfer.

The Use of Thermoporometry in the Study of Frost Resistance of Rocks.

From an engineering point of view, it is important to know the factors influencing the frost resistance of rocks with porosity above 2% due to their different frost resistance. The article focused on frost durability research using the thermoporometry method (TMP) and the assessment of water phase transition in the pore spaces of selected rocks. For this purpose, the differential scanning calorimetry method (DSC) was used with the adoption of an original algorithm for eliminating the thermal inertia of the measurement system. The results of the DSC method were supplemented with the results of pore size distribution using the mercury intrusion porosimetry method (MIP) and standard rock frost resistance tests. Based on the research carried out using the thermoporometry method, it was confirmed that the ability of water to freeze in the temperature range from -5 °C to -20 °C was important, as well as the ability of rocks to increase the degree of water saturation during freeze-thaw cycles. Based on calorimetric tests combined with thermoporometry, in the case of non-frost-resistant rocks, a significant (dominant) share of pores with a radius of under 10 nm (amounting to over 0.008 cm3/cm3) was found. Pore connections in the water freezing process do not influence the investigated rocks' frost resistance.

A comprehensive thermal analysis of icemaking process inside a domestic freezer: Theoretical, numerical and experimental analyses

Automatic icemakers are integrated into refrigerators to ensure a consistent ice supply and improve energy efficiency. Despite these advantages, a thorough investigation of the automatic icemaking process in domestic refrigerator-freezers is lacking in the literature. This study aims at assessing the performance of automatic icemaking process in a domestic freezer through detailed theoretical, numerical and experimental analyses. A simplistic zero-dimensional transient energy balance model is developed to investigate the heat transfer during different stages of the water solidification process. The convective heat transfer coefficient calculated from the theoretical analysis is used to inform the numerical model. A three-dimensional transient model is proposed to predict the temperature and density variation inside the ice cube modelled as a pyramid. The free surface flow is modelled using volume of fluid method, while enthalpy-porosity method is employed for the water freezing process. The results show a non-uniform temperature distribution throughout the solidification process and that the temperature of the outer frozen layers keeps decreasing with the solidification time. Experiments are conducted to measure the temperature variation of the ice cube. It is shown that the icemaking process is accelerated by around 18 % when the ice-removal temperature is set at −8°C instead of −12 °C, which is a conventional set temperature for ice remover in current domestic freezers.

Cryoprotective Effect of Pectin Tanacetan from Tanacetum vulgare L.

We researched the ability of tanacetan pectin from inflorescences of common tansy Tanacetum vulgare L. to change the osmolarity and freezing point of water in solutions of cryoprotectants: glycerol-3.5%, dimethyl sulfoxide (DMSO)-10%, dimethylacetamide-10% (DMAC), and 1.2-propanediol (1.2-PD)-10%, as well as the effect of solutions of tanacetan (0.2%, 0.4%) on the kinetics of crystallization processes and the nature of crystal formation. We used a combination of protector and pectin that we tested earlier, which provided effective protection for human leukocytes and platelets, as well as bovine spermatozoa, at temperatures below freezing (-20°C and -80°C). It has been established that tanacetan slows down the process of water freezing in glycerol, but not in DMSO, DMAC, and 1.2-PD, promotes deeper supercooling of the medium, and affects the morphological structure of ice. The addition of pectin to the cryosolution increases the activity of the main cryoprotectant glycerol even at its low concentrations. The combination of glycerol and tanacetan can be effective in freezing biological materials, which is confirmed by the preservation of leukocytes at -20°C and -80°C for 7 days, platelets at -80°C for 30 days, and spermatozoa at -80°C within 1 day. A comprehensive analysis of the chemical, physicochemical, and cryoprotective properties of tanacetan indicates the prospect of using pectin in the cryopreservation of biological objects at temperatures of electric freezers.

Experimental Study on Adhesive Characteristics of Aircraft Dynamic Icing

The adhesive properties of aircraft icing play an important role in guiding the design of protection systems, while the formation environment, freezing process, and measurement methods have a great impact on the mechanical characteristics of ice, leading to significant differences in the available experimental results. Therefore, to improve the proximity between the experimental simulation and the actual process of inflight ice shedding, a generation system for the water cloud environment was built and integrated with a set of rotary measuring mechanisms in this paper, allowing the adhesion strength of impact ice to be measured online. In the present test, the appearance characteristics of ice formed under different conditions were observed and analyzed, with the range of its adhesion strength determined. And the effects of freezing mode, ambient temperature, and wind speed on ice adhesion were further discussed. It can be found that the impact ice has a more irregular shape and less adhesion compared to the static ice, and this difference will grow larger with the drop in ambient temperature. In addition, the adhesion of ice first increases and then decreases with the rising ambient temperature, reaching the maximum value (0.254 MPa) around −12 °C. When the flow velocity in the test section increases, the freezing process of water on the substrate will slow down, leading to greater surface adhesion.

Sea water freezing modes in a natural convection system

Sea ice is crucial in many natural processes and human activities. Understanding the dynamical couplings between the inception, growth and equilibrium of sea ice and the rich fluid mechanical processes occurring at its interface and interior is of relevance in many domains, ranging from geophysics to marine engineering. Here we investigate experimentally the complete freezing process of water with dissolved salt in a standard natural convection system, i.e. the prototypical Rayleigh–Bénard cell. Due to the presence of a mushy phase, the studied system is considerably more complex than the freezing of fresh water in the same conditions (Wanget al.,Proc. Natl Acad. Sci. USA, vol. 118, issue 10, 2021, e2012870118). We measure the ice thickness and porosity at the dynamical equilibrium state for different initial salinities of the solution and temperature gaps across the cell. These observables are non-trivially related to the controlling parameters of the system as they depend on the heat transport mode across the cell. We identify in the experiments five out of the six possible modes of heat transport. We highlight the occurrence of brine convection through the mushy ice and of penetrative convection in stably stratified liquid underlying the ice. A one-dimensional multi-layer heat flux model built on the known scaling relations of global heat transport in natural convection systems in liquids and porous media is proposed. Given the measured porosity of the ice, it allows us to predict the corresponding ice thickness, in a unified framework.

Spontaneous peeling of ice accretion: A novel expansion force de-icing unit based on phase transition time lag

The problem of ice accreted has posed a serious threat to industry and life. In recent years, it has received extensive attention, and a large number of anti-icing and de-icing technologies have been developed. However, even the best-performed anti-icing surface would face ice-forming issue under continuously extreme conditions, which increase the importance of easily ice removal. Although passive methods represented by icephobic surfaces have show great advantages, a more applicable method is the spontaneous peeling of ice under disturbance. Therefore, it is of great significance to develop efficient and reliable de-icing methods. In this paper, a spontaneous de-icing unit based on phase transition time lag is designed by utilizing the expansion force of the water freezing process. The effects of ambient temperature on expansion force, adhesion force, and phase transition lag time are explored, the factors of pit shape and ethanol concentration are introduced. Finally, without relying on energy input, spontaneous peeling of ice was achieved under disturbance and remained effective after 100 icing-deicing cycles.

NUMERICAL STUDY ON HEAT TRANSFER WITHIN A ROCK-AIR-WATER-ICE SYSTEM UNDER CRYOGENIC CONDITIONS

A numerical heat transfer model which couples heat conduction, natural convection, and the freezing process is built with ANSYS FLUENT. Then, 2D simulations of heat transfer in a rock-air-water-ice system under the cryogenic conditions are conducted by using the model for studying heat transfer mechanism in the reservoir stratum during cryogenic fracturing. The effects of air and water on the local temperature evolution are analyzed from the perspectives of thermophysical properties, natural convection, and the water freezing process. For thermophysical properties, it is found that the influence of volumetric heat capacity is significant in the early stage of heat transfer, while in a long-term heat transfer process the effect of thermal conductivity is dominant. Natural convection alters the cold energy distribution and exerts different influences on the local temperature variation, and these effects could be weakened due to the presence of water. The release of latent heat due to water freezing delays the decrease of local temperature, while the newly formed ice phase accelerates the decrease of local temperature due to its relatively high thermal conductivity compared with that of water. Besides, the effect of water distribution on heat transfer is analyzed. Variation in water distribution alters the range and intensity of the impact brought by natural convection and water freezing, affecting the temperature evolution. The combined effect of natural convection and water freezing affects the local temperature variation differently, depending on the time and position concerned.

In Situ Growth of a Stable Metal-Organic Framework (MOF) on Flexible Fabric via a Layer-by-Layer Strategy for Versatile Applications.

Fabrics have been used broadly in daily life for an enormous variety of applications due to their intrinsic advantages, such as flexibility, renewability, and good processability. Integrating natural fabrics with metal-organic frameworks (MOFs) is an effective strategy to improve the added value of textiles with special functionalities. Here, a facile, low-cost, and scalable technology is reported for the in situ growth of MOFs on cotton fabrics. A uniform and dense coating of regular octahedral Cu-1,3,5-benzenetricarboxylic acid (CuBTC) crystals was formed on the fiber surface, followed by treatment with 1H,1H,2H,2H-perfluorooctyltriethoxysilane and triethoxyoctylsilane to create a superhydrophobic CuBTC@cotton fabric (SMCF), which greatly improved its water stability and extended superhydrophobic CuBTC's potential applications. The as-prepared MCF has a specific surface area of 229 m2/g, which is 11 times that of pristine fabrics (21 m2/g). This high porosity further endows the fabric with enhanced loading capacity of essential oils to enable excellent antibacterial ability. Moreover, the SMCF also exhibits excellent self-cleaning, UV shielding, and anti-icing performances. In addition, we performed COMSOL simulations to investigate the dynamic freezing process of water on the surface of samples, which agrees well with our experimental observations. By combining the merits of both fabrics and MOFs, the MCF is expected to extend the applications of traditional textiles in antifouling, safety, the fragrance industry, and healthcare for the next-generation multifunctional fabrics.

Distribution of florfenicol and norfloxacin in ice during water freezing process: Dual effects by fluorine substituents

Distribution in ice is regarded as one of important transport modes for pollutants in seasonal freeze-up waters in cold regions. However, the distribution characteristics and mechanisms of fluorinated antibiotics as emerging contaminants during the water freezing process remain unclear. Here, florfenicol and norfloxacin were selected as model fluorinated antibiotics to investigate their ice-water distribution. Effects of antibiotic molecular structure on the distribution were explored through comparative studies with their non-fluorinated structural analogs. Results showed that phase changes during the ice growth process redistributed the antibiotics, with antibiotic concentrations in water 3.0–6.4 times higher than those in ice. The solute-rich boundary layer with a concentration gradient was presented at the ice-water interface and controlled by constitutional supercooling during the freezing process. The ice-water distribution coefficient (KIW) values of antibiotics increased by 34.8%–38.0% with a doubling of the cooling area. The solute distribution coefficient (Kbs) values of antibiotics at −20 °C were 65.6%–70.3% higher than at −10 °C. The KIW and Kbs values of all antibiotics were negatively correlated with their water solubilities. The fluorine substituents influenced the binding energies between antibiotics and ice, resulting in a 1.1-fold increase in the binding energy of norfloxacin on the ice surface relative to its structural analog pipemidic acid. The results provide a new insight into the transport behaviors of fluorinated pharmaceuticals in ice-water systems.

Preparation and anti-icing performance of acrylic superhydrophobic asphalt pavement coating with microwave heating function

In winter, icing greatly reduces the friction performance of pavement and brings a high safety hazard to road traffic. We prepared a superhydrophobic coating (SHC) with a microwave heating function to minimize pavement icing risk. The static contact angle of the water droplet on the SHC is 161.2°. The freezing time of water droplets on asphalt mixture coated with SHC is 1.63 times longer than that of asphalt mixture without coating. SHC can significantly delay the freezing process of water. The normal adhesion strength of 10 mm ice layer on the asphalt mixture coated with the SHC at −5 °C is only 14.3 % of that on the asphalt mixture without coating. It confirms that the SHC dramatically reduces the normal adhesion strength of the ice layer on asphalt pavement. In addition, the microwave heating rate of the asphalt mixture coated with SHC is 48.37 % faster than that of the asphalt mixture without coating. Carbon nanotube particles directly contact the ice on the SHC surface. Besides, carbon nanotube particles also have high microwave heat conversion efficiency and high thermal conductivity. The ice layer on the surface of the asphalt mixture coated with SHC can be melted and removed within 80 sec, which is 42.86 % faster than the ice removal time of asphalt mixture without coating. Carbon nanotube particles on the SHC surface were directly heated by microwaves and melted the ice layer rapidly. The acrylic coating on the asphalt mixture surface has an excellent thermal insulation performance. The load wheel rolling experiment was conducted to simulate the traffic wheel friction. The static contact angle of the water droplet on the SHC keeps at 147°, and the microwave heating performance of the SHC has no significant changes before and after 500 rolling times. This implies that the SHC has sustainable superhydrophobic properties and can melt the ice layer under microwave heating even after the traffic wheel friction. The SHC is of great significance for improving the driving safety of asphalt pavement.

Experimental study of water freezing process improvement using ultrasound

The phase change process of freezing water is an important application in several fields such as ice making, food freezing technologies, pharmaceuticals, etc. Due to the widespread usage of ice-related products, process improvements in this technology can potentially lead to substantial energy savings. It is well known that supercooling has a negative effect on the overall time and energy consumption of the freezing process. Therefore, ultrasound is proposed as a technique to improve the freezing process by eliminating the supercooling effect and the resulting energy savings is investigated. An experimental study was conducted to analyze the energy expenditures in the freezing process with and without the application of ultrasound. After a set of preliminary experiments, an intermittent application of ultrasound at 3.52 W & 8.25 W power levels was found to be more effective than constant-power application. The supercooling phenomenon was thoroughly studied through iterative experiments. It was also found that the application of ultrasound during the freezing process led to the formation of shard-like ice crystals. From the intermittent ultrasound experiments performed at 3.52 W & 8.25 W power levels, energy savings relative to no-ultrasound processes of 12.4% and 10.8% were observed, respectively.

Changes in the interfacial stress of water on aluminum alloy surface during the freezing and thawing process

In a low-temperature environment, water or moisture adhere to the material surface and freeze into ice, and it is not easy to remove. The accumulated ice has affected many engineering fields. In the study, the change law of the interface stress related to the ice adhesion strength during the freezing process of water on the aluminum alloy was studied under different test conditions. The experiment found that the maximum freezing interface stress of water on the aluminum alloy surface gradually increased with the decrease of the test temperature and the increase of the water volume. Combined with the analysis of the freezing process, the interface stress gradually increased after the water on the aluminum alloy surface entered into the supercooled state. Due to the influence of heat released by phase change and volume expansion, the freezing interface stress of ice could be reduced. Afterward, the freezing interface stress remained stable. During the thawing process, the interfacial stress increased suddenly and then gradually decreased with the temperature of the test temperature rise to a room temperature of 20 °C. The present research would be helpful to understand the mechanism of ice adhesion on the material surface and the formation mechanism of ice adhesion strength, and provide a reference for the development and optimization of anti/de-icing technology in the engineering field.

Effect of Graphene on Ice Polymorph

Recently, ice with stacking disorder structure, consisting of random sequences of cubic ice (Ic) and hexagonal ice (Ih) layers, was reported to be more stable than pure Ih/Ic. Due to a much lower free energy barrier of heterogeneous nucleation, in practice, the freezing process of water is controlled by heterogeneous nucleation triggered by an external medium. Therefore, we carry out molecular dynamic simulations to explore how ice polymorphism depends on the lattice structure of the crystalline substrates on which the ice is grown, focusing on the primary source of atmospheric aerosols, carbon materials. It turns out that, during the nucleation stage, the polymorph of ice nuclei is strongly affected by graphene substrates. For ice nucleation on graphene, we find Ih is the dominant polymorph. This can be attributed to structural similarities between graphene and basal face of Ih. Our results also suggest that the substrate only affects the polymorph of ice close to the graphene surface, with the preference for Ih diminishing as the ice layer grows.

Changes of Water/Ice Morphological, Thermodynamic, and Mechanical Parameters During the Freezing Process

To reduce ice adhesion hazards, optimize or develop the anti/de-icing methods, it is necessary to understand the change of freezing parameters during the freezing process, such as thermodynamic, morphological, and mechanical parameters. The present study investigates the freezing characteristics by purpose-built devices to describe the freezing process quantitatively. Morphological parameters were calculated the reverse engineering. The results showed that the inner temperature and morphology of water droplet were obviously changed, and the freezing process could be mainly divided into three stages: initial and spreading, freezing, and steady-state. Moreover, an experimental apparatus that measured the phase swelling force was built on investigating the freezing process of water from the mechanical aspect. It was found that the swelling force generated from the freezing process of 2473 mm3 water could reach 46.38 N. The generation process of swelling force could also be separated into three stages: non-expansive stage, increasing stage, and stable stage. The formation stage of swelling force was similar to that of ice. Combining the measured expansion force with the calculated freezing parameters based on the observed test, the freezing process of water could be better understood. The study would help researchers and engineers understand the freezing process and provide some freezing characteristics parameters for the anti/de-icing research.

Insights into Design of Biomimetic Glycerol-Grafted Polyol-Based Polymers for Ice Nucleation/Recrystallization Inhibition and Thermal Hysteresis Activity.

Many species living in colder regions of the world have adapted to the extreme climate by producing antifreeze (glycol) proteins (AF(G)P) which exhibit ice recrystallization inhibition (IRI), thermal hysteresis activity (THA), as well as other interactions with the freezing process of water. Although several synthetic approaches for the exploitation of these proteins have been investigated, challenges remain in the synthetic design of biomimetic polymers. Similar to biological antifreezes, poly(vinyl alcohol) (PVA) has potent IRI activity; however, by comparison, PVA has very little THA. In this study, we explored structural variations to polyol-based polymers to contrast with PVA as a control and identified several key structural elements for performance in IRI, THA, as well as in ice nucleation inhibition (INI). These structural features are bioinspired by the typical ice-binding plane of AFPs yet are surprisingly simple to produce with potency approaching that of typical AFPs. Key to the performance is positioning small organic functionalities with known antifreeze properties (such as ethylene glycol) pendent to a host polymer chain with consideration of their conformational freedom. To build systematic variations into both the backbone and side-chain structures, we used poly(vinyl alcohol), poly(isopropenyl acetate), poly(acrylic acid), and poly(methacrylic acid) parent polymers for such pendent modifications. One structure in particular, glycerol-grafted-PVA (G-g-PVA), shows potency rivaling that of AFPs at similar micromolar concentration. The findings in this study help guide the rational design of synthetic antifreeze polymers useful for applications such as anti-icing coatings through to cryopreservation methods for organ transport and cell preservation.

Phase-field model of graphene aerogel formation by ice template method

A phase-field model is exploited to simulate the microstructure of graphene aerogel formation during the water freezing process. The nucleation of ice grains and the graphene redistribution play significant roles in preparation of graphene aerogel by the ice template method. Our simulation clarifies the process of polycrystalline ice nucleation, the graphene redistribution between the ice-water interface and the anisotropic growth process of ice grains. The result shows that the morphology and size of the graphene wall structure in aerogel are derived from the comprehensive effects of ice nucleation, polycrystalline growth, and graphene diffusion. The present study therefore contributes to the understanding of graphene aerogel formation and provides guidance for experiments to design a high specific surface area, light weight, and high strength three-dimensional porous structure.

STUDIES OF WATER FREEZING FEATURES IN ICE CREAM WITH STARCH SYRUP

The purpose of the study is to research the process of water freezing in new types of ice cream with starch syrup at certain stages of the technological process. Starch syrup as a degradation product of corn starch is characterized by different values of the dextrose equivalent (DE). Starch syrup is a source of solids, sweetener, cryoprotectants (at high DE) and thickener (for low values of DE). The starch syrups with fundamentally different functional and technological properties are chosen for the study: high glucose-fructose syrup HGFS-98 (DE = 98) and low-sugar starch syrup GFS-30 (DE = 30). To determine the size of ice crystals in ice cream, a light microscope of the brand XS-2610 with a cooling chamber is used for an increase of x600, and the cryoscopic temperature is measured by cryostat and Beckmann thermometer (TL-1) to calculate the content of frozen out water. The regularities of the process of water freez-out in ice cream with milk fat content of 3.5%, creamy fat content of 10% and filling with fat content of 15% in the temperature range from minus 6ºС to minus 40ºС are established. In particular, the content of frozenwater in ice-cream at certain stages of the technological process is determined. The results are used to optimize the prescription composition of ice cream with starch syrup. It is recommended to use hydrocarbon complexes consisting of HGFS-98 and GFS-30 in the ratio of 30:70 to 80:20 to reduce the content of frozen water in ice cream of different chemical compositions. The results of the study are of practical importance and allow to obtain in production conditions the fine-crystalline structure of ice cream with starch syrup.

Influence of Micro and Nanosilica on the Frost–Heave Process

Frost-heave of soils is an important problem in engineering practice. Thus, it became necessary to find an adequate method that would reduce the negative effect of this phenomenon on building structures. The paper presents the preliminary tests results of microsilica (MS) and nanosilica (NS) influence on the water freezing process in frost-susceptible soils. The selection of stabilising additives also allowed for the analysis of changes that result from their transition from micro to nanoscale. For the purposes of the experiment a test stand was constructed, that enables to analyse six samples at the same time, at inflow of water from the bottom and freezing direction from the top. The use of linear potentiometer displacement sensors allowed to measure the increase in the height of samples automatically. Additionally, the measurement stand was equipped with digital semiconductor temperature sensors, so temperature could be measured at various heights of the samples. Moreover, an array of electrodes was applied to measure the electrical conductivity of soil at various levels of samples, which enabled the analysis of changes that occur in freezing soil. The tests were conducted according to the BS 812-124:1989 standard, in three variants: soil, soil + 5% MS, soil + 5% NS. The obtained results demonstrated that the addition of microsilica reduces the occurrence of ice lenses, which in turn significantly decreases the growth in sample height. However, the addition of nanosilica completely stops the frost-heave process. Ice lens is not created, only a frost line is noticeable. Analysing the distribution of temperatures at different heights, it was noted that stabilised samples are characterised by higher temperature in comparison to the soil without additives. This means that the analysed stabilisers reduce the degree of freezing of the soil mixture. The highest temperatures were noted in samples stabilised with nanosilica. Conductivity tests also demonstrated that the smallest changes occurred in samples stabilised with nanosilica. This results from the fact that ice lenses did not occur in such samples. In order to analyse the obtained results and their interpretation thoroughly, it is necessary to perform a detailed analysis of the microstructure both of soil and of soil with stabilising additives.