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Journal articles on the topic 'Capillary and porous materials'

Author: Grafiati

Published: 30 May 2022

Last updated: 31 May 2022

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1

Sychevskii, V. A. "Drying of colloidal capillary-porous materials." International Journal of Heat and Mass Transfer 85 (June 2015): 740–49. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.02.025.

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2

Horikawa, Toshihide, D. D. Do, and D. Nicholson. "Capillary condensation of adsorbates in porous materials." Advances in Colloid and Interface Science 169, no. 1 (November 2011): 40–58. http://dx.doi.org/10.1016/j.cis.2011.08.003.

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3

Tuchinskii, L. I., M. B. Shtern, and S. A. Zakharov. "Sintering kinetics of capillary-porous powder materials." Powder Metallurgy and Metal Ceramics 32, no. 6 (June 1993): 486–90. http://dx.doi.org/10.1007/bf00560725.

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4

Ratanadecho, P., K. Aoki, and M. Akahori. "Influence of Irradiation Time, Particle Sizes, and Initial Moisture Content During Microwave Drying of Multi-Layered Capillary Porous Materials." Journal of Heat Transfer 124, no. 1 (September 10, 2001): 151–61. http://dx.doi.org/10.1115/1.1423951.

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The drying of capillary porous materials by microwave with rectangular waveguide has been investigated numerically and experimentally. Most importantly, it focuses on the investigation of the distributions of electric field, temperature and moisture profiles within the capillary porous materials. The measurements of temperature and moisture distributions within the capillary porous materials provide a good basis for understanding of the microwave drying process. The mathematical model gives qualitatively comparable trends to experimental data. The calculations of electromagnetic fields inside the rectangular waveguide and the capillary porous materials show that the variation of particle sizes and initial moisture content changes the degree of penetration and rate of microwave power absorbed within the sample. Further, the small particle size leads to much higher capillary pressure resulting in a faster drying time.

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5

Snezhkin, Yu F., V. М. Paziuk, and Zh O. Petrova. "Heat pump technologies of low temperature drying of capillary-porous materials spherical shape." Кераміка: наука і життя, no. 3(48) (October 12, 2020): 7–12. http://dx.doi.org/10.26909/csl.3.2020.1.

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Heat pump technologies have become widely used in space heating and air conditioning systems, and the heat pump can be used for low-temperature drying of capillary-porous materials. Recuperative and condensing heat pumps, which allow both drying and cooling of the material, have become the most widespread. The developed condensing heat pump drying unit with a mine chamber implements a low-temperature drying process of spherical capillary-porous materials at a drying agent temperature of 40-50°C with a decrease in material humidity by 11% to a final humidity of 8%. Experimental studies on a heat pump drying unit for drying capillary-porous materials of spherical shape indicated a significant reduction in average energy costs per process up to 3700 - 4100 kJ/kg of evaporated moisture. The increase in energy consumption increases significantly in the second part of the second period, where heat consumption can reach 5000 - 5350 kJ/kg of evaporated moisture. The use of condensing heat pumps for low-temperature drying of capillary-porous materials has shown high energy efficiency compared to existing drying technologies.

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6

Gamayunov, N. I., and S. N. Gamayunov. "Shrinkage and Strength of Capillary-Porous Colloidal Materials." Journal of Engineering Physics and Thermophysics 77, no. 1 (January 2004): 45–52. http://dx.doi.org/10.1023/b:joep.0000020718.82001.6f.

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7

Denesuk, M., G. L. Smith, B. J. J. Zelinski, N. J. Kreidl, and D. R. Uhlmann. "Capillary Penetration of Liquid Droplets into Porous Materials." Journal of Colloid and Interface Science 158, no. 1 (June 1993): 114–20. http://dx.doi.org/10.1006/jcis.1993.1235.

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8

Kostornov, A. G., A. A. Shapoval, and I. V. Shapoval. "Skeletal heat conductivity of porous metal fiber materials." Kosmìčna nauka ì tehnologìâ 27, no. 2 (May 17, 2021): 70–77. http://dx.doi.org/10.15407/knit2021.02.070.

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The influence of a number of physical characteristics and parameters of metallic fiber materials on their thermal conductivity is studied in this work. Such porous materials are intended, among other things, for their effective use in two-phase heat transfer devices (heat pipes). The use of heat pipes in aircraft and space vehicles provides a number of thermophysical advantages. In particular, heat pipes significantly expand the possibilities of air cooling of heat-loaded technical devices. The thermal conductivity of capillary-porous materials-structures, which are important elements of heat pipes, significantly affects the intensity of two-phase heat transfer inside heat pipes. Frame thermal conductivity is equivalent to the thermal conductivity of materials that are conditionally continuous medium. Studies of the influence of structural characteristics of porous materials, such as porosity and parameters (dimensions) of discrete particles-fibers (fractions of the studied materials), were performed using special experimental equipment created at the I.M. Frantsevich Institute for Problems of Materials Science of the National Academy of Sciences of Ukraine (Kyiv). Porous metal structures (coatings) made of copper, nickel, and steel fibers (MPM) were investigated under conditions similar to those for space heat pipes. The porosity values of the prototypes of materials were in the range of 40 to 93%. The research results showed that the following physical characteristics of capillary structures, such as values of thermal conductivity of metallic materials (fiber fractions), the porosity of capillary-porous metal materials (structures), significantly affect the value of thermal conductivity of porous materials. The dimensions of discrete particles-fibers also affect in a certain way the value of the MBM thermal conductivity but to a lesser degree. The results obtained in this work are summarized in the form of empirical dependencies – formulas, providing engineering calculations of the thermal conductivity values of metal fiber materials. The research results are intended for practical application in aviation and spacecraft apparatus engineering. In particular, the presented results are necessary for the development and creation of effective heat pipes with metal fiber capillary structures.

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9

Sheleg, V. K. "Increasing the efficiency of application of capillary-porous powder materials. I. Parameters of the efficiency of capillary-porous powder materials." Soviet Powder Metallurgy and Metal Ceramics 30, no. 3 (March 1991): 214–16. http://dx.doi.org/10.1007/bf00794909.

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10

Sheleg, V. K. "Increasing the efficiency of using capillary-porous powder materials. II. Materials with steady capillary flow." Soviet Powder Metallurgy and Metal Ceramics 30, no. 5 (May 1991): 407–11. http://dx.doi.org/10.1007/bf00793669.

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11

Alsabry, Abdrahman, Beata Backiel-Brzozowska, Vadzim I. Nikitsin, and Serafim K. Nikitsin. "Equations for Calculating the Thermal Conductivity of Capillary-Porous Materials with over Sorption Moisture Content." Sustainability 14, no. 10 (May 11, 2022): 5796. http://dx.doi.org/10.3390/su14105796.

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This article is the result of the authors’ work on the method of calculating the effective thermal conductivity of moist capillary-porous materials used in wall partitions. The proposed methodology was developed based on the theory of generalized conductivity and geometric modeling of the structure. Materials are considered as heterogeneous ternary systems consisting of a solid skeleton, gas and liquid, and all components are simultaneously taken into account in the calculation. In this work, additional equations are constructed that allow calculation of the effective thermal conductivity of capillary-porous materials with over sorption moisture, thus extending the scope of application of the method to the entire possible range of changes in moisture content. The details of calculating the thermal conductivity of moist capillary-porous materials are demonstrated using experimental data for wall ceramics samples. It is shown that the proposed equations are capable of predicting the thermal conductivity of moist capillary-porous materials with sufficient accuracy. Knowledge of the thermal conductivity of materials in conditions of their actual moisture is fundamental in the sustainable design of new buildings as well as thermo-renovation and dump protection of historic ones.

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12

Ha, Jonghyun, and Ho-Young Kim. "Capillarity in Soft Porous Solids." Annual Review of Fluid Mechanics 52, no. 1 (January 5, 2020): 263–84. http://dx.doi.org/10.1146/annurev-fluid-010518-040419.

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Soft porous solids can change their shapes by absorbing liquids via capillarity. Such poro-elasto-capillary interactions can be seen in the wrinkling of paper, swelling of cellulose sponges, and morphing of resurrection plants. Here, we introduce physical principles relevant to the phenomena and survey recent advances in the understanding of swelling and shrinkage of bulk soft porous media due to wetting and drying. We then consider various morphing modes of porous sheets, which are induced by localized wetting and swelling of soft porous materials. We focus on physical insights with the aim of triggering novel experimental findings and promoting practical applications.

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13

Snezhkin, Yu F., V. М. Paziuk, and Zh O. Petrova. "Mathematical processing of results experimental studies of low-temperature modes of drying of capillary-porous materials of spherical shape." Кераміка: наука і життя, no. 1(42) (April 6, 2019): 20–25. http://dx.doi.org/10.26909/csl.1.2019.3.

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The mathematical processing of experimental data obtained during the drying of spherical form of capillary-porous materials on a convective drying bench allows us to determine the influence of various factors on the process. The main factors influencing the kinetics of drying of capillary-porous materials of spherical shape are the temperature and velocity of the heat carrier, as well as the initial moisture content of the material. For each factor, the variation levels corresponding to the optimal conditions for conducting experimental studies with low-temperature drying conditions are recommended. For a mathematical description of the duration of drying of capillary-porous materials, we use an orthogonal composite plan of the second order. As a result, the proposed mathematical model of the process obtained regression equations and the response surface of the duration of drying of capillary-porous materials of spherical shape. The obtained regression equations of the drying time give a detailed description of the influence of both individual and joint actions of factors, the significance of these parameters is determined by the corresponding coefficients according to Student's criterion. Also, the adequacy of the mathematical model according to Fisher's criterion, which corresponds to the real object, is checked. The construction of the response surfaces of the drying time of capillary-porous materials indicates the nature of the effect of these factors in the given range of variation.

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14

Avraamov, N. I., A. V. Korolkov, V. A. Maslov, and V. B. Sapozhnikov. "Mathematical Simulation of Using a Combination of Mesh and Porous Materials as a Phase Separator." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 3 (126) (June 2019): 4–16. http://dx.doi.org/10.18698/0236-3941-2019-3-4-16.

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A combination of mesh and porous materials featuring bulk capillary properties is used as a phase separator in in-tank capillary inlet devices. These bulk capillary properties ensure a non-zero fluid flow into the interior of the in-tank inlet device after critical pressure has been reached. This quality makes it possible to reduce residual propellant volume in spacecraft engine tanks. We developed a mathematical simulation of an in-tank capillary inlet device comprising a phase separator made of a combination of mesh and porous materials. We represented a combination of mesh and porous materials as an array of "closely packed" transverse and longitudinal capillaries. Our mathematical simulation describes the operation of an in-tank inlet device after the critical manifold pressure has been reached. The fluid enters the interior of the in-tank inlet device one portion at a time. We determined the volume and arrival frequency of these portions and estimated the residual propellant volume in the propellant tank.

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15

Pazyuk, V. М. "Investigation of low-temperature drying modes plant capillary-porous materials spherical shape." Кераміка: наука і життя, no. 4(41) (December 28, 2018): 7–14. http://dx.doi.org/10.26909/csl.4.2018.1.

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The results of experimental studies of the drying of capillary-porous materials of spherical shape from the influence of the temperature of the heat carrier are given.Spherical granules with a diameter of 2,2 mm were taken to determine the rational modes of drying of capillary-porous materials. For a better evaluation of the nature of the drying process, experimental design studies were carried out on a convective drying stand in an elementary layer.The program of automatic collection and processing of information allows obtaining data on changes in the mass and temperature of the sample during the removal of moisture, and also performs calculations of kinetics of drying in absolute and relative coordinates. This makes it possible to obtain and compare the kinetic and velocity characteristics of colloid capillary-porous materials drying faster, more accurately and reliably.By the method of Krasnikov V.V. the kinetics of drying of capillary-porous materials of spherical shape with a diameter of 2,2 mm with construction of a generalized drying curve with determination and calculation of drying coefficients is considered.The generalized curve of drying rate is constructed and obtained, which allows us to generalize the process of drying of a capillary-porous spherical material. Also, get the formula and determine the overall length of the drying process through the drying rate for each heat treatment.When comparing the values of the process length obtained by experimental studies and determined by the calculations, the experimental error from the calculation does not exceed 3%.The analysis of heat-mass-exchange processes of drying by means of calculations of temperature coefficient b, Rebinder Rb criterion, heat flow q and coefficient of heat transfer α from the influence of heat carrier temperature has been carried out.

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16

Elsen, J., and F. de Barquin. "Simulieren der kapillaren Wasseraufnahme von porösen Werkstoffen des Bauwesens / Modelling of the Capillary Water Absorption of Porous Building Materials." Restoration of Buildings and Monuments 6, no. 3 (June 1, 2000): 293–306. http://dx.doi.org/10.1515/rbm-2000-5477.

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Abstract Profound knowledge of the moisture transport in porous building materials is essential to understand and to improve their durability. Water flow in these materials is mainly driven by capillary forces and the capillary suction of a porous building material depends on its pore structure. We have designed a statistical model to simulate the capillary water absorption of porous building materials based on invasion percolation rules. A 3D-network with 30x30x100 sites was used and the trapping effect is included. The input for the simulated invasion percolation is a pore size distribution obtained by a stereological analysis of the results of automated image analysis measurements on SEM-BSE-images of polished sections. Pore size distributions of nine different materials have been determined experimentally by SEM and by MIP. The simulated absorption curves agree reasonably well with the experimental absorption curves.

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17

Vidales, A. M., R. J. Faccio, and G. Zgrablich. "Capillary hysteresis in porous media." Journal of Physics: Condensed Matter 7, no. 20 (May 15, 1995): 3835–43. http://dx.doi.org/10.1088/0953-8984/7/20/004.

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18

Hartung, Katharina, Carolyn Benner, Norbert Willenbacher, and Erin Koos. "Lightweight Porous Glass Composite Materials Based on Capillary Suspensions." Materials 12, no. 4 (February 19, 2019): 619. http://dx.doi.org/10.3390/ma12040619.

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In this article, we present a simple, advanced method to produce lightweight tailor-made materials based on capillary suspensions that are made from locally bonded hollow glass spheres with a high total porosity in the range of 70% at apparent densities of 200 kg/m3, having a compressive strength of 0.6 MPa. The amount of added liquid and the particle surface treatment determine the network structure in the pastes and the resulting microstructure of the porous material in a straightforward manner. This structure has a strong impact on the porosity, pore size, and mechanical properties of the final body. The most promising porous materials were made of surface treated hollow glass spheres that create a sample-spanning network in the capillary state, where the added liquid wets the particles worse than the bulk fluid. These samples approach the density of natural balsa wood and they may find application in fields where either weight or structure are important, such as in insulation materials, filters, and membranes, as well as lightweight construction materials for automotive or aerospace engineering.

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19

Petrova, Zh O., B. V. Davydenko, and K. S. Slobodianiuk. "Modeling of heat and mass transfer in the process of drying of colloid capillary - porous materials." Кераміка: наука і життя, no. 2(43) (July 7, 2019): 7–14. http://dx.doi.org/10.26909/csl.2.2019.1.

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The process of drying is an energy-consuming process, therefore, in order to optimize these energy costs during drying and to choose the rational structural and regime parameters of the equipment intended for this process, it is necessary to carry out a calculation analysis of heat and mass transfer on the basis of adequate mathematical models. The study of various mechanisms of diffusion in capillary - porous materials has become the basis for the creation of a mathematical model of heat - mass transfer and for the formulation of a corresponding system of nonlinear differential equations. Using mathematical model of heat-mass transfer A.V. Lykova constructed an appropriate numerical algorithm for modeling this process, numerical studies of the convection drying process of colloidal capillary - porous materials (KKPM) have been performed. The boundary conditions on the contact surface of the material in the drying chamber with the heat carrier flow are formulated. Based on the numerical solution of the system of one-dimensional heat and mass transfer equations in the material, depending on the time of its specific moisture content and temperature, as well as other characteristics of the convection drying process, the dependence was obtained. The estimated results are compared with the results of experimental studies. From the results of the comparison, it follows that the calculated model on the basis of the proposed system of equations satisfactorily describes the process of mass transfer in colloidal capillary - porous materials and can be used to approximate the characteristics of the drying process of colloidal capillary - porous materials, in particular the time required for drying the material. Numerical modeling of heat and mass transfer processes in colloid capillary and porous materials helps to solve an important scientific and technical problem, which is connected with the creation of software and hardware complexes, automated systems of scientific researches of energy-saving heat-technological processes of drying of materials with the provision of necessary quality indicators. Having analyzed the literature data concerning the existing developed mathematical modeling of colloidal capillary-porous materials, it has been established that this direction has a limited amount of information and therefore requires in-depth study and is an actual direction of research.

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20

Kryuchkov, Yu N. "Determination of the Average Capillary Radius of Porous Materials." Glass and Ceramics 75, no. 3-4 (July 2018): 139–44. http://dx.doi.org/10.1007/s10717-018-0043-4.

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21

Hirsch, Hauke, Rüdiger Heyn, and Paul Klõšeiko. "Capillary condensation experiment for inverse modelling of porous building materials." E3S Web of Conferences 172 (2020): 17003. http://dx.doi.org/10.1051/e3sconf/202017217003.

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Hygrothermal simulations are of major importance for critical problems in building physics, such as the application of internal insulation in heritage buildings. These simulations require numerous material parameters that are challenging to determine. We present measurements of typical internal insulation materials, calcium-silicate and autoclaved aerated concrete, which we expose to a warm, humid climate on one side and a cold temperature on the other side. We measure the moisture gain over time and determine the moisture profile at experiment end. In an inverse modelling approach, the measurements are used to identify material parameters, in particular vapour conductivity and capillary conductivity as a function of moisture content. We found the measurements of crucial importance for the accurate determination of these parameters. When the parameters rely only on isothermal measurements such as the drying experiment, the model fails to predict the capillary condensation process. We demonstrate this on a dataset from another study with interior insulation subjected to changing boundary conditions. The model calibrated with capillary condensation data reliably reconstructs measurements while the drying-calibrated model drastically underestimates the moisture content.

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22

Wang, Li Cheng, and Shu Hong Li. "Numerical Solutions for Capillary Absorption by Cementitious Materials." Applied Mechanics and Materials 94-96 (September 2011): 1560–63. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.1560.

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Capillary absorption is essential to mass migration in cementitious materials. Based on previous studies, capillary rise involving gravity effects is of much greater interest in porous building materials because equilibrium is attained at the wetting front when gravitational force balance the capillary force. In this paper, two different solution forms, semi-analytical and numerical, are presented to account for the gravity effect for realistical prediction of water penetration process. The former is stable against small perturbation proved by Stepanyants [1]. The comparison of predicted results by the two methods confirms the reliability of the technique in estimating water transport.

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23

Pilinevich, L. P., M. V. Tumilovich, A. G. Kravtsov, D. M. Rumiantsav, and K. V. Hryb. "Research of the process of obtaining capillary-porous materials from metal powders for heat pipes." Doklady BGUIR 19, no. 4 (July 1, 2021): 5–12. http://dx.doi.org/10.35596/1729-7648-2021-19-4-5-12.

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Heat pipes are designed to effective removing heat from heating elements and reducing the temperature of various devices. Heat pipes with capillary porous structures are designed to operate under conditions of unfavorable gravity forces. Their main advantages are their high heat transfer capacity, as well as the ability to retain the coolant in a capillary-porous structure under dynamic power loads. The purpose of this work is to study the process of obtaining capillary-porous materials from metal powders for heat pipes with increased efficiency of using the vibration molding method. The article substantiates the relevance of creating heat pipes from metal powders. The information about the influence of the contact angle, surface tension and capillary pressure on the heat transfer capacity of a heat pipe is provided. It is shown that for the efficient operation of the heat pipe it is necessary to create such a capillary structure of the porous material, which could simultaneously provide a high speed of movement of the coolant and its rise to a given height. The above requirements can be satisfied by creating a capillary structure using powder metallurgy methods by optimizing the distribution of pore sizes. In this case, the most promising method seems to be the method of molding when applying a vibration to a mold with a powder. It is possible to obtain the required pore distribution in this way by choosing the correct particle size, shape and vibration parameters. This makes it possible to ensure the packing of particles in size, which affects their packing density, pore size, tortuosity and length of pore channels. The distribution of the maximum pore sizes over the thickness of the samples obtained from powders of various granulometric composition with the use of vibration has been investigated. As a result, a process was developed for obtaining capillary structures by the method of vibration molding of metal powders, depending on the size of the powder particles, the amplitude and frequency of vibration. It is shown that this method can provide a given pore distribution of the capillary structure for heat pipes, which makes it possible to increase their heat transfer capacity.

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24

Alsabry, Abdrahman, Beata Backiel-Brzozowska, and Vadzim I. Nikitsin. "Dependencies for Determining the Thermal Conductivity of Moist Capillary-Porous Materials." Energies 13, no. 12 (June 20, 2020): 3211. http://dx.doi.org/10.3390/en13123211.

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A method of determining the effective thermal conductivity of moist capillary-porous materials has been proposed, in which calculations are carried out while taking into account all components of the system (solid, liquid and gas) at once. The method makes it easy to take into account the way water is distributed in the pore space of the material, either as isolated inclusions (drops) or as a continuous component, depending on the moisture content of the material. In the analysis of heat transport in moist capillary-porous materials, the theory of generalized conductivity is used and the structure of moist material is modeled using an ordered geometric structure consisting of identical unit cells in the form of a cube. An equation is obtained for calculating the effective conductivity of capillary-porous materials with isolated and continuous liquid inclusions, with adiabatic and isothermal division of the unit cell. The proposed method is compared to the previously proposed method of determining the effective thermal conductivity of moist materials, in which the three-component system is gradually reduced to a binary system, showing disadvantages of this method compared to the currently proposed. It has been shown that the proposed formulas grant the possibility of a sufficiently accurate prediction of experimental results using the experimental results of the thermal conductivity of moist aerated concrete.

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25

Wang, J., J. J. Xu, Y. Yang, X. J. Wang, X. Luo, L. Zhang, and G. Jiang. "Simulations on the gelling process of particle suspension systems for in-situ preparing porous materials in a capillary." International Journal of Modern Physics B 29, no. 04 (February 10, 2015): 1550015. http://dx.doi.org/10.1142/s0217979215500150.

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The gelling process of particle suspension in a capillary which is crucial for in-situ preparing small size foam products has been simulated with an off-lattice diffusion limited cluster aggregation (DLCA) model by the three-dimensional Monte Carlo simulations. The effects of the model parameters, such as the interaction between capillary wall and particles, particle volume fraction, capillary size etc. on the density distribution of the system have been fully explored. And the aggregation kinetics process over a broad range of volume fractions and interactions have also been discussed. The results show that the geometric constraint of capillary can be analogous to a weak repulsive interaction between capillary wall and particles. And we found that as the capillary size or particle volume fraction increase, particle concentration distribution will be more uniform with other parameters constant. Porous network with relatively uniform density distribution can be also obtained through controlling the interaction between capillary wall and particles. In addition, by analyzing the aggregation kinetics process, we found that the attraction of capillary wall dramatically reduces the probability of gelation in the small-scale capillary. The obtained results will be of great importance in controlling the density distribution of porous materials prepared by in-situ methods.

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26

Zhang, Jianyong, Junxing Chen, Sheng Peng, Shuyin Peng, Zizhe Zhang, Yexiang Tong, Philip W. Miller, and Xiu-Ping Yan. "Emerging porous materials in confined spaces: from chromatographic applications to flow chemistry." Chemical Society Reviews 48, no. 9 (2019): 2566–95. http://dx.doi.org/10.1039/c8cs00657a.

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27

Sheleg, V. K. "Increasing the efficiency of using capillary-porous powder materials. III. Infiltrating materials." Soviet Powder Metallurgy and Metal Ceramics 30, no. 7 (July 1991): 588–91. http://dx.doi.org/10.1007/bf00794651.

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28

JOEKAR-NIASAR, V., S. M. HASSANIZADEH, and H. K. DAHLE. "Non-equilibrium effects in capillarity and interfacial area in two-phase flow: dynamic pore-network modelling." Journal of Fluid Mechanics 655 (July 5, 2010): 38–71. http://dx.doi.org/10.1017/s0022112010000704.

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Current macroscopic theories of two-phase flow in porous media are based on the extended Darcy's law and an algebraic relationship between capillary pressure and saturation. Both of these equations have been challenged in recent years, primarily based on theoretical works using a thermodynamic approach, which have led to new governing equations for two-phase flow in porous media. In these equations, new terms appear related to the fluid–fluid interfacial area and non-equilibrium capillarity effects. Although there has been a growing number of experimental works aimed at investigating the new equations, a full study of their significance has been difficult as some quantities are hard to measure and experiments are costly and time-consuming. In this regard, pore-scale computational tools can play a valuable role. In this paper, we develop a new dynamic pore-network simulator for two-phase flow in porous media, called DYPOSIT. Using this tool, we investigate macroscopic relationships among average capillary pressure, average phase pressures, saturation and specific interfacial area. We provide evidence that at macroscale, average capillary pressure–saturation–interfacial area points fall on a single surface regardless of flow conditions and fluid properties. We demonstrate that the traditional capillary pressure–saturation relationship is not valid under dynamic conditions, as predicted by the theory. Instead, one has to employ the non-equilibrium capillary theory, according to which the fluids pressure difference is a function of the time rate of saturation change. We study the behaviour of non-equilibrium capillarity coefficient, specific interfacial area, and its production rate versus saturation and viscosity ratio.A major feature of our pore-network model is a new computational algorithm, which considers capillary diffusion. Pressure field is calculated for each fluid separately, and saturation is computed in a semi-implicit way. This provides more numerical stability, compared with previous models, especially for unfavourable viscosity ratios and small capillary number values.

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29

Hird, Robert, and Malcolm D. Bolton. "Migration of sodium chloride in dry porous materials." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2186 (February 2016): 20150710. http://dx.doi.org/10.1098/rspa.2015.0710.

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Groundwater can saturate soil above the water table within the capillary fringe associated with the pore size of the parent soil. External evaporation has been viewed as a mechanism for enhancing upward flow, potentially creating problems of salt heave beneath roads and foundations if the groundwater is saline, analogous to concerns with efflorescence in masonry. The role of internal evaporation in promoting crystallization, and especially in altering the transport process of the pore fluid, has been recognized but is only partially understood. The purpose of this paper is to examine evidence for the upward percolation of brine accompanying salt crystallization inside a porous granular material. A series of experiments are described using vertical flow columns packed with dry sand above a reservoir of saline fluid, to explore whether salt transport could take place by autogenous wicking above the initial capillary fringe. The conditions inside the columns were monitored at specific elevations with sensors measuring bulk electrical conductivity, dielectric constant and relative humidity. Dendritic salt crystallization was observed inside the sand, accompanying surface heave. Ultimately, efflorescence on the surface led to the formation of a salt crust. Some implications for the potential damage to roads and foundations in arid regions, and to masonry subject to rising damp, are discussed.

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30

Lago, Marcelo, and Mariela Araujo. "Capillary Rise in Porous Media." Journal of Colloid and Interface Science 234, no. 1 (February 2001): 35–43. http://dx.doi.org/10.1006/jcis.2000.7241.

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31

Petrova, Zh O., V. M. Vyshnievskyi, Yu P. Novikova, and A. I. Petrov. "Investigation of the dispersion processes of composite colloidal capillary-porous materials." Кераміка: наука і життя, no. 4(45) (December 27, 2019): 21–25. http://dx.doi.org/10.26909/csl.4.2019.3.

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The technology of drying colloidal capillary-porous materials to a final humidity of 6-8%, developed at the Institute of Technical Thermophysics of the NAS of Ukraine, allowed to obtain a brittle state, in which it is possible to grind this product to small particles. The most suitable for industrial grinding of the dried composite colloidal capillary-porous materials is the impact method, because when wiping and crushing the material has accumulated, stuck to the working surface. Powders are characterized by one pronounced maximum corresponding to the particle size of the powder of 0,16 mm. As the rotation speed of the shredder rotor changes, the particle size distribution of 0,16 mm increases by reducing the larger particles. The amount of powder thus obtained is directly proportional to the speed of rotation of the rotor. The study of the dispersion and classification of functional powders showed that all powders have the largest particle size of 0,16 mm. The maximum yield of this fraction is 70% and the lowest is 40%. The structural-mechanical characteristics of powders from composite colloidal capillary-porous materials were investigated for the first time. Characteristics of different fractions were determined by such parameters as bulk density, vibration density, angle of natural slope, speed of material flow through the funnel and others. Studies to determine the structural and mechanical properties of functional powders have shown that they can be attributed to more bulk powders, as opposed to highly bound monopowders. Creating compositions improves their structural and mechanical properties.

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32

Shen, Vincent K., Daniel W. Siderius, and Nathan A. Mahynski. "Molecular simulation of capillary phase transitions in flexible porous materials." Journal of Chemical Physics 148, no. 12 (March 28, 2018): 124115. http://dx.doi.org/10.1063/1.5022171.

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33

Kirianova, Liudmila. "Mathematical model of the porous-capillary body in construction materials." IOP Conference Series: Materials Science and Engineering 365 (June 2018): 042027. http://dx.doi.org/10.1088/1757-899x/365/4/042027.

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34

Petrova, Zh A., and E. S. Slobodyanyuk. "Energy-Efficient Modes of Drying of Colloidal Capillary-Porous Materials." Journal of Engineering Physics and Thermophysics 92, no. 5 (September 2019): 1231–38. http://dx.doi.org/10.1007/s10891-019-02038-x.

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35

Akulich, P. V., and N. N. Grinchik. "Modeling of heat and mass transfer in capillary-porous materials." Journal of Engineering Physics and Thermophysics 71, no. 2 (March 1998): 225–33. http://dx.doi.org/10.1007/bf02681539.

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36

Gel'miza, V. I. "Failure of porous capillary materials under high-intensity thermal loading." Soviet Applied Mechanics 24, no. 6 (June 1988): 620–23. http://dx.doi.org/10.1007/bf01890823.

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37

Lukovičová, Jozefa, Gabriela Pavlendová, Ivan Baník, and Rudolf Podoba. "Determination of Poroelastic Parameters of Porous Building Materials." Defect and Diffusion Forum 353 (May 2014): 189–92. http://dx.doi.org/10.4028/www.scientific.net/ddf.353.189.

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Variations of sorption moisture in the capillary porous materials result in strong fluid-skeleton interactions due to molecular and surface forces, which produce moisture-induced deformation. The effect of moisture sorption on the non-linear elastic behavior of hygroscopic porous building materials has been experimentally investigated showing strong influence of moisture especially in the lower moisture content range. In the framework poroelasticity moisture influence on elastic behavior is described by two poroelastic coefficients, which present the fluid-skeleton coupling. This paper presents an application of the procedure for the determination of the coupling coefficients for medieval brick.

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38

Škramlík, Jan, Miloslav Novotný, Ondřej Fuciman, and Karel Šuhajda. "3D Data for Calculation of Capillary Conductivity Coefficient." Advanced Materials Research 688 (May 2013): 180–84. http://dx.doi.org/10.4028/www.scientific.net/amr.688.180.

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The moisture in building construction material affects the physical properties of buildings and he may lead to their degradation. With few exceptions, building materials are almost never dry. For the expected negative effect of moisture on building materials of structures is needed accurate method of determining the characteristics of their moisture as possible. The capillary conductivity coefficient characterizes transfer of liquid moisture in porous material. The method for its determination is experimentally arranged in such a way that it is possible to apply diffusion equation derived from the Luikov equation that is a phenomenological description of liquid moisture transport in porous materials as well as from the continuity equation, which expresses the classic conservation of matter principle. To records of the moisture distribution has been developed the methodology for measuring of moisture in the porous material, using microwave radiation. The calculation of the capillary conductivity coefficient and its dependence is based on the moisture curves in 3 D in non-stationary state of wetting, determined by non-destructive method.

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39

Zamytskyi, O. V., N. O. Holiver, N. V. Bondar, and S. O. Kradozhon. "Mathematical model of the process of drying fine dispersed materials under the influence of alternating electric current." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 3 (2021): 51–56. http://dx.doi.org/10.33271/nvngu/2021-3/051.

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Purpose. Establishing the dependences and determining rational parameters of the process of drying fine materials by direct influence of an electric current. Methodology. In the work, theoretical, analytical, empirical, and experimental methods as well as methods of mathematical statistics are used. Mathematical modeling of the process occurring during drying of finely dispersed materials by direct influence of alternating current is carried out. Findings. As a result of the research on the basis of physical representations of the process of drying capillary-porous material, a mathematical model is designed connecting temperature and moisture content in a plate from capillary-porous material by means of equations of mathematical physics. Originality. For the first time dependence has been obtained on the temperature and moisture content of the time and spatial coordinates of drying by passing an electric current through the layer of moist capillary-porous material, a feature which is both simultaneous accounting of thermal and diffusion processes in the material that can increase the accuracy of calculations and establish rational parameters of drying. Practical value. The obtained dependences are used when developing calculation methods and designing an industrial drying plant.

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40

Fan, Jie, Cai-Xia Li, Yuan-Yuan Qi, Li-Li Wang, Wan Shou, and Yong Liu. "Liquid transport in non-uniform capillary fibrous media." Textile Research Journal 89, no. 9 (May 29, 2018): 1684–98. http://dx.doi.org/10.1177/0040517518779248.

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Liquid transport in porous materials is affected significantly by the geometry of the non-uniform capillaries. In this study, an N-section lotus-rhizome-node-like non-uniform capillary model was for the first time proposed based on the plane Poiseuille flow and capillary pressure equation to investigate the liquid transport in porous fibrous media. Normalized total flow time of the non-uniform capillary was obtained as a function of the height and width ratio between the converging and diverging nodes and their total number. The results indicated that the velocity of liquid transport greatly depended on the number of nodes in a certain liquid transport length. The non-uniform capillaries with frequent alterations between converging and diverging nodes have low liquid transport efficiency. The thick capillary exhibits fast liquid transport efficiency in those capillaries with the same self-similar geometry. The model was verified using polypropylene filament yarns and different liquids. The results agreed well with the theoretical prediction. This work not only provides a deeper understanding of liquid transport inside porous fibrous media with non-uniform capillaries, but can also guide the novel design and optimization of functional fibrous materials.

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Basok, Borys, Borys Davydenko, and Anatoliy M. Pavlenko. "Numerical Network Modeling of Heat and Moisture Transfer through Capillary-Porous Building Materials." Materials 14, no. 8 (April 7, 2021): 1819. http://dx.doi.org/10.3390/ma14081819.

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The article presents the modeling of the dynamics of the vapor-gas mixture and heat and mass transfer (sorption-desorption) in the capillary structure of the porous medium. This approach is underpinned by the fact that the porous structure is represented by a system of linear microchannels oriented along the axes of a three-dimensional coordinate system. The equivalent diameter of these channels corresponds to the average pore diameter, and the ratio of the total pore volume to the volume of the entire porous material corresponds to its porosity. The entire channel area is modeled by a set of cubic elements with a certain humidity, moisture content, pressure and temperature. A simulation is carried out taking into account the difference in temperatures of each of the phases: solid, liquid and gas.

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42

Hall, Christopher. "Capillary water absorption by a porous cylinder." Journal of Building Physics 42, no. 2 (August 21, 2017): 120–24. http://dx.doi.org/10.1177/1744259117724523.

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Capillary absorption (imbibition) of water by a porous cylinder is described by means of a Sharp-Front model. The cumulative absorption increases as (time)1/2 at early times, but more slowly as the wet front approaches the cylinder axis. Results are given in terms of dimensionless variables. Experimental data on plaster cylinders are in good agreement with theory. Estimates of the sorptivity and effective porosity of the material can be obtained. The model may be useful in testing drilled cores and may also be applied to radial flow through the wall of a porous tube (hence to conduits and arches).

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43

Acquaroli, Leandro N., Raúl Urteaga, Claudio L. A. Berli, and Roberto R. Koropecki. "Capillary Filling in Nanostructured Porous Silicon." Langmuir 27, no. 5 (March 2011): 2067–72. http://dx.doi.org/10.1021/la104502u.

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44

Taurbayev, Y. T., K. A. Gonchar, A. V. Zoteev, Victor Timoshenko, Z. Zh Zhanabayev, V. E. Nikulin, and T. I. Taurbayev. "Electrochemical Nanostructuring of Semiconductors by Capillary-Cell Method." Key Engineering Materials 442 (June 2010): 1–6. http://dx.doi.org/10.4028/www.scientific.net/kem.442.1.

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Wafers of silicon and compound semiconductors are nanostructured by using electrochemical or chemical etching (stain etching) in etching cell with electrolyte kept by capillary forces. Atomic force microscopy, infrared spectroscopy and Raman scattering methods reveale nanoporous and nanocrystalline structure of the treated surfaces. The formed porous semiconductors demonstrate efficient photoluminescence, which is controlled by etching parameters, i.e. current density, electrolyte content, etc. These results indicate good prospects of the employed capillary-cell method for preparing nanostructured porous materials with desired structure and optical properties.

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45

Primi, P., and F. H. Wittmann. "Einfluss des Feuchtigkeitsgehaltes auf das kapillare Saugen / Influence of Moisture Content on Capillary Suction." Restoration of Buildings and Monuments 2, no. 5 (October 1, 1996): 415–26. http://dx.doi.org/10.1515/rbm-1996-5132.

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Abstract Some surface treatments such as hydrophobing and realcalisation rely on capillary suction as the driving force. In this context, the critical admissible moisture content must be known. The porous structure of a series of different building materials has been characterized. The porosity and pore size distribution has been determined on 3 different types of autoclaved aerated concrete (AAC), on samples made of hardened cement paste with 3 different water-cement ratios, on natural sandstone and on burned brick. The sorption isotherm and at each equilibrium moisture content the remaining capillary suction has been measured on identical specimens. It can be shown that capillary suction of materials with a coarse porous structure such as sandstone or burnt brick depends slightly only on the moisture content Capillary suction of hardened cement paste with a fine porous system, in contrast, is drastically diminished with increasing moisture content and reaches negligible values near 100 % RH. Results presented in this contribution allow us to fix a critical admissible moisture content for different building materials. At the same time, building materials can be identified for which the moisture content has to be carefully controlled before surface treatment is to be applied It must be mentioned, however, that in critical cases the moisture profile must be determined up to the intended depth of the treatment instead of the surface moisture content.

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46

Suchorab, Zbigniew, Marcin K. Widomski, Grzegorz Łagód, Danuta Barnat-Hunek, and Piotr Smarzewski. "Methodology of Moisture Measurement in Porous Materials Using Time Domain Reflectometry / Metodyka Prowadzenia Badań Wilgotności W Ośrodkach Porowatych Za Pomocą Reflektometrii W Domenie Czasu." Chemistry-Didactics-Ecology-Metrology 19, no. 1-2 (December 1, 2014): 97–107. http://dx.doi.org/10.1515/cdem-2014-0009.

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Abstract The article presents the description of measurement methodology of moisture transport in unsaturated porous materials using Time Domain Reflectometry (TDR) technique on the example of measurement of capillary uptake phenomenon in the sample of autoclaved aerated concrete (AAC). In the paper there are presented basic principles of the TDR method as a technique applied in metrology, its potential for measurement of moisture in porous materials like soils and porous building materials. Second part of the article presents the experiment of capillary rise process in the sample of AAC. Within the experiment moisture content was monitored in the sample exposed on water influence. Monitoring was conducted using TDR FP/mts probes. Preparation of the measuring setup was presented in detail. The TDR readouts post-processing, graphical presentations of the obtained results, short discussion and comparison of TDR readouts to gravimetric measurement were also presented.

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47

Labai, V. Yo, and L. Ya Soroka. "KINETIC CHARACTERISTICS OF CONVECTION DRYING PROCESS OF CAPILLARY-POROUS COLLOIDAL MATERIALS." Scientific Bulletin of UNFU 27, no. 10 (January 30, 2018): 86–88. http://dx.doi.org/10.15421/40271015.

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48

Malkin, E. S., and R. V. Lutsyk. "Study into the Thermodynamic Properties of Wet Colloid Capillary-Porous Materials." Heat Transfer Research 29, no. 4-5 (1998): 281–87. http://dx.doi.org/10.1615/heattransres.v29.i4-5.100.

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49

YOSHIMOTO, Yuta, Takuma HORI, Ikuya KINEFUCHI, and Shu TAKAGI. "Effect of capillary condensation on gas transport properties in porous materials." Proceedings of Mechanical Engineering Congress, Japan 2017 (2017): J0530307. http://dx.doi.org/10.1299/jsmemecj.2017.j0530307.

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50

Grosman, Annie, and Camille Ortega. "Nature of Capillary Condensation and Evaporation Processes in Ordered Porous Materials." Langmuir 21, no. 23 (November 2005): 10515–21. http://dx.doi.org/10.1021/la051030o.

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