Water Transfer Properties Research Articles

Effect of wet grinding carbonation of sintering red mud on the performance of carbon sequestered mortar

The use of alkaline solid waste to CO2 capture is a potential way to upgrade the recycling of solid waste and reduce CO2 emission. In previous work, we proposed a novel wet grinding carbonation technique to achieve rapid carbonation of sintering red mud (SRM). Herein, the effect of wet grinding carbonation of SRM (WGCS) replacement rate (0 %, 5 %, 10 %, 15 %, 20 % and 25 %) on the hydration and hardening of Portland cement was further explored, such as rheology, compressive strength, hydration products and water transfer properties. The plastic viscosity and yield stress of carbon sequestered paste rose together with the WGCS replacement rate, which was due to the decreased D50 of SRM after wet grinding carbonation. When the WGCS replacement rate was 15 %, the 56 d compressive strength of carbon sequestered mortar was increased by 14.1 %. The microscopic characterization showed that the nucleation of calcite crystals and the pozzolanic reaction of silica-rich gels clearly improved the microstructure compactness. The electric flux and porosity of cement mortar was decreased by 25.7 % and 11.4 %, respectively. In terms of environmental and economic benefits, the CO2 sequestration of carbon sequestered mortar reached as high as 24.7 kg/m3 and the CO2 emission was reduced by 30.9 %.

A Simple, Mild, and Low‐Cost Method for Preparation of Wood‐Nigrosine in Solar‐Driven Interfacial Evaporation System

The solar‐driven interfacial evaporation system has attracted much attention in recent years due to its reduced heat loss and accelerated steam generation. As a low‐cost and readily available resource, wood is widely applied as photothermal materials in solar‐driven interfacial evaporation system because of its superior water transfer and heat loss prevention properties. Herein, a simple, mild, and cost‐effective method is employed to fabricate wood‐based photothermal materials. The results demonstrate that the solar absorption rate of wood‐nigrosine is more than 97.5% across a wide wavelength range (200–2500 nm), and an evaporation rate of 1.46 kg m−2 h−1 and evaporation efficiency (86.1%) are achieved under 1‐sun illumination (100 mW cm−2). The solar‐driven interfacial evaporation system based on wood‐nigrosine exhibits strong structural stability and processing capability for dyes and seawater.

The effect of mercerization on water conductivity in cotton fabrics and its regulation

AbstractMercerization had been widely used in the textile industry because of its simplicity and ability to improve the luster, strength, and dyeing properties of cotton fabrics. However, the water transfer behavior of mercerized cotton fabrics had not been systematically investigated. In this work, cotton fabrics were treated with different concentrations of alkali (130 and 260 g/L) for structural characterization (scanning electron microscopy [SEM], Fourier transform infrared [FTIR]), water absorption (vertical wicking height), moisture absorption (moisture return rate), water retention, and so forth, and were compared with industrial mercerized cotton. It meant that water absorbency and water holding capacity of mercerized cotton textiles were improved by reducing surface impurity, increasing amorphous region, and increasing the number of free hydroxyl groups. It was easier for water molecules to move through the fabric as the vertical wicking height increased. Research showed that the water absorption and water transfer properties of cotton fabrics were related to the alkali concentration in the mercerized treatment, and a comparison with industrial mercerized cotton also proved this point. It also showed that the amount of tension had an effect on water transfer in the fabric, which provided further precision in regulating the mercerization process, improving the thermal comfort of mercerized fabrics, and achieving the aim of regulating the mercerization process according to market demand and environmental influences.

Water molecules jump through non-aligned disjoint nanochannels

The intricate design of nanochannels results in varying water transfer capabilities. The disjoint nanochannel provides a unique challenge to water molecules. However, the disjoint nanochannels are coaxial, in this study, we explore the transfer of water molecules through non-aligned disjoint nanochannels. Our findings reveal that the noncoaxial separation significantly influences water transfer properties in non-aligned disjoint nanochannels. Specifically, the formation of a water bridge is affected by the noncoaxial separation, and water molecules cannot jump through these non-aligned disjoint nanochannels when the noncoaxial separation reaches a critical point. Our results provide insights into the behavior of water in complex nanochannels.

3D computational fluid dynamics-based analysis of water transfer characteristics of hollow fiber membrane for gas-to-gas membrane humidifier

Water in a proton exchange membrane fuel cell is the main factor determining its performance and durability. A humidifier provides water vapor to regulate the humidity of the fuel cell and enable proper operation. The water transfer properties of membranes are investigated through experiments, and simulations enable faster prediction and optimization of various operating conditions. In this study, a numerical simulation model using the diffusion coefficient empirical formula was developed to calculate the water vapor transport. User-defined function codes are applied to predict mass transfer using the concentration difference between the wet and dry surfaces of the membrane. The results were analyzed by the water transfer rate, mass fraction, and pressure characteristics of the influence of flow rate, pressure, temperature, humidity, and the number of membranes of 9 or 21. The analysis model predicted the experimental results with high reliability of R-square 0.96. It was confirmed that a high flow rate increased the outlet water transfer flux, and an increase in the tube decreased the water transfer flux.

Hygric and thermal properties of Slovak building sandstones

Recently, the simulation software (HAM) used for heat and water transport has become a powerful tool for the hygrothermal analysis of building envelopes, particularly for historical buildings. The increased moisture content and poor thermal-insulation properties of historical building materials increase the risk of damage to the masonry and surface finish. Renovation design and reconstruction is a complicated process. Input data such as boundary conditions, initial conditions, and material properties are required to model the complex heat and water transfer in buildings using a simulation tool. This study focuses on determining the hygric and thermal properties of sandstone from locations in eastern Slovakia that were previously used for historic building construction. The basic thermal, water storage, and water transfer properties were determined using experimental methods. An accurate description of these parameters allows for dynamic simulations of hygrothermal behaviour using the HAM simulation tools for the purposes of restoring historical buildings of immense heritage significance.

Accelerating water transport through a disjoint nanochannel with a large nanogap

Water transport through a disjoint nanochannel is important for understanding water molecules confined in a complex nanostructure. However, the transport behavior of water molecules in the disjoint nanochannel is affected by the nanogap of the disjoint nanochannel greatly. It is still difficult to transfer water molecules through the disjoint nanochannel with a large nanogap even under high pressure. In this article, we report water transfer properties through a disjoint nanochannel with a large nanogap under the influence of an electric field. By the aid of the electric field, the efficiency of water transfer through a (10, 0) disjoint nanochannel is enhanced sharply. The transfer of water molecules through a (12, 0) disjoint nanochannel and a (14, 0) disjoint nanochannel increases under an appropriate electric field but decreases under a strong electric field. Our findings are beneficial to achieve a stable and fast water transport through a disjoint nanochannel.

The role of vadose zone physics in the ecohydrological response of a Tibetan meadow to freeze–thaw cycles

Abstract. The vadose zone is a zone sensitive to environmental changes and exerts a crucial control in ecosystem functioning and even more so in cold regions considering the rapid change in seasonally frozen ground under climate warming. While the way in representing the underlying physical process of the vadose zone differs among models, the effect of such differences on ecosystem functioning and its ecohydrological response to freeze–thaw cycles are seldom reported. Here, the detailed vadose zone process model STEMMUS (Simultaneous Transfer of Energy, Mass and Momentum in Unsaturated Soil) was coupled with the ecohydrological model Tethys–Chloris (T&C) to investigate the role of influential physical processes during freeze–thaw cycles. The physical representation is increased from using T&C coupling without STEMMUS enabling the simultaneous mass and energy transfer in the soil system (liquid, vapor, ice) – and with explicit consideration of the impact of soil ice content on energy and water transfer properties – to using T&C coupling with it. We tested model performance with the aid of a comprehensive observation dataset collected at a typical meadow ecosystem on the Tibetan Plateau. Results indicated that (i) explicitly considering the frozen soil process significantly improved the soil moisture/temperature profile simulations and facilitated our understanding of the water transfer processes within the soil–plant–atmosphere continuum; (ii) the difference among various representations of vadose zone physics have an impact on the vegetation dynamics mainly at the beginning of the growing season; and (iii) models with different vadose zone physics can predict similar interannual vegetation dynamics, as well as energy, water, and carbon exchanges, at the land surface. This research highlights the important role of vadose zone physics for ecosystem functioning in cold regions and can support the development and application of future Earth system models.

A New Fractal Approach to Account for Capillary and Adsorption Phenomena in the Water Retention and Transfer Properties of Unsaturated Soils

AbstractTo describe the water retention and transfer properties of an unsaturated soil over the whole range of matric suction, it is necessary to account for both capillary and adsorption phenomena. Existing models combine well‐known empirical functions for capillary water at lower suctions and more physically based ones for adsorptive water at higher suctions. To determine their full set of parameters, they however require different optimization procedures, among which those coming from capillary models are empirical. In this context, the main objective of this work is to develop a simple and robust physically based model of the water retention and transfer properties of unsaturated soils valid from saturation to oven dryness. To do so, new capillary‐based water retention and hydraulic conductivity functions founded on the fractal approach have been derived from the pore size distribution, by means of the Young‐Laplace law and Mualem's model. To describe adsorption phenomena, these functions are combined with those used in the Peters‐Iden‐Durner (PID) model, providing a model along the full range of suctions, with less parameters than the existing models. Our work also shows that some parameters are directly determined from the experimental grain size distribution data (the fractal dimension), or from the water retention data (air entry suction and residual water content), leaving only two parameters to be optimized. The model was successfully validated with respect to published experimental data from 10 different coarse, sandy, and clayey soils.

Effect of knitting structure and yarn composition on thermal comfort properties of bi-layer knitted fabrics

In this work, nine bi-layer knitted samples with varied knitting structures and made up of different yarn compositions were fabricated, and their thermal comfort properties were investigated. The thermal comfort properties were evaluated by breathability, water transfer properties, thermo-physiology properties and dynamic cooling properties, and their relationship with fabric knitting structure and yarn composition were investigated statistically. It was observed that bi-layer knitted fabrics with meshes at one side had better air permeability, moisture management properties, drying performance, thermo-physiological properties and dynamic cooling function, but lower wicking height than bi-layer knitted fabrics with trim and symmetrical structure (without meshes). The composition of nylon and polyester filaments with varied wettability as outer and inners layer of bi-layer knitted fabrics, respectively, improved the water one-way transport capacity significantly. In particular, bi-layer fabrics with asymmetric structure and made up of yarns with varied hydrophilicity as each layer have excellent moisture management capacity. Moreover, fabrics made up of yarns with finer fibers exhibited better thermal comfort properties.

Water retention and transfer properties of a Green roof volcanic substrate

The water retention curve and the hydraulic conductivity function of a volcanic coarse granular material used as a substrate in an urban green roof in the Paris area was carried out on a newly developed device, in which low suctions were controlled. In the same cell, a hanging column system was used for controlling smaller suctions (up to 32 kPa) and the axis translation technique for larger suctions (up to 50 kPa). Water exchanges were monitored in connected tubes by using a high accuracy differential pressure transducer. The step changes in suction were also used to determine the hydraulic conductivity function by means of Gardner’s method, accounting for the impedance effects due to the high air entry value ceramic porous disk with Kunze and Kirkham’s method. van Genuchten and Brooks and Corey models were used for the water retention curve, but the hydraulic conductivity functions derived from these expressions appeared to lead to a significant under-estimation, confirming the need of operational and simple device for the experimental determination of the hydraulic conductivity function.

TiO2 Nanocrystal Based Coatings for the Protection of Architectural Stone: The Effect of Solvents in the Spray-Coating Application for a Self-Cleaning Surfaces

A colloidal route was exploited to synthesize TiO2 anisotropic nanocrystal rods in shape (TiO2 NRs) with a surface chemistry suited for their dispersibility and processability in apolar organic solvents. TiO2 NRs were dispersed in chloroform and n-heptane, respectively, and the two resulting formulations were investigated to identify the optimal conditions to achieve high-quality TiO2 NR-based coatings by the spray-coating application. In particular, the two types of TiO2 NR dispersions were first sprayed on silicon chips as a model substrate in order to preliminarily investigate the effect of the solvent and of the spraying time on the morphology and uniformity of the resulting coatings. The results of the SEM and AFM characterizations of the obtained coatings indicated n-heptane as the most suited solvent for TiO2 NR dispersion. Therefore, an n-heptane dispersion of TiO2 NRs was sprayed on a highly porous limestone—Lecce stone—very commonly used as building material in historic constructions and monuments present in Apulia Region (Italy). A comprehensive physical-chemical investigation of the TiO2 NR based treatment on the surface of the stone specimens, including measurements of colour variation, static contact angle, water transfer properties, and morphological characterization were performed. Finally, the photocatalytic properties of the coatings were assessed under solar irradiation by using Lecce stone specimens and Methyl Red as a model target compound. The obtained results demonstrated that TiO2 NRs based coatings can be successfully applied by spray-coating resulting in an effective photocatalytic and hydrophobic treatment, which holds great promise as a material for the environmental protection of architectural stone in the field of cultural heritage conservation.

Influence of surfactants and proteins on the properties of wet edible calcium alginate meat coatings

Calcium alginate structures are of interest as replacers for natural casings due to their high availability, biodegradability and low price. The aim of this paper is to study the effect of oil, surfactants and proteins (pea and collagen) on the water transfer, mechanical and microstructural properties of the wet calcium alginate films. The addition of oil and surfactants tended to reduce the water permeance and the weight loss rate, reaching values between those shown by natural and collagen artificial casings. The addition of proteins did not improve the adherence of the films and it decreased the maximum force of the film at puncture test, which was even lower with the presence of the surfactant E475. The TEM micrographs showed that the differences in mechanical properties are mainly related to the differences in the compaction of the microstructure. Wet alginate films with E475 are envisaged as a substitute of natural and collagen artificial casings in the stuffed meat products industry.

Hydration and water vapour transport properties in yeast biomass based films: A study of plasticizer content and thickness effects

Research on biodegradable films is a topic of strategical interest in the field of food science and technology. These films are membranes conformed by biopolymers that interact strongly with water and they generally require the addition of plasticizer in order to improve its integrity and mechanical properties. The study of the hydration and water transfer properties through these films, as well as understanding in what way the thickness and the addition of the plasticizer affect these properties, is essential for a better knowledge and optimization of the required protective function of these membranes. In this work the hydration kinetics and water transport through biodegradable films obtained from yeast biomass were studied, in order to know the performance against changes in thickness and glycerol content. Hydration kinetics experiments allowed obtaining solubility of water in the matrix film, and the diffusion coefficient. Results demonstrated that when glycerol content was increased, the solubility of water increased while diffusion remained constant. Moreover, when the film thickness was grown, the solubility of water decreased but the diffusion increased. Experimental water vapour permeability obtained through traditional cup method was compared to the theoretical permeability calculated by multiplying diffusion coefficient and water solubility. The good agreement observed between both values allowed the analysis of how solubility and diffusion contributed to permeability. As a result this study revealed that the increment of permeability with the plasticizer content was due to the increase in solubility, while the effect of the thickness increasing permeability was dominated by diffusion.

Directional Trans-Planar and Different In-Plane Water Transfer Properties of Composite Structured Bifacial Fabrics Modified by a Facile Three-Step Plasma Treatment

Fabrics with moisture management properties are strongly expected to benefit various potential applications in daily life, industry, medical treatment and protection. Here, a bifacial fabric with dual trans-planar and in-plane liquid moisture management properties was reported. This novel fabric was fabricated to have a knitted structure on one face and a woven structure on the other, contributing to the different in-plane water transfer properties of the fabric. A facile three-step plasma treatment was used to enrich the bifacial fabric with asymmetric wettability and liquid absorbency. The plasma treated bifacial fabric allowed forced water to transfer from the hydrophobic face to hydrophilic face, while it prevented water to spread through the hydrophobic face when water drops were placed on the hydrophilic face. This confirmed one-way water transport capacity of the bifacial fabric. Through the three-step plasma treatment, the fabric surface was coated with a Si-containing thin film. This film contributed to the hydrophobic property, while the physical properties of the fabrics such as stiffness and color were not affected. This novel fabric can potentially be used to design and manufacture functional and smart textiles with tunable moisture transport properties.

Colloidal Nanocrystalline Semiconductor Materials as Photocatalysts for Environmental Protection of Architectural Stone

Rod-shaped TiO2 nanocrystals (TiO2 NRs), capped by oleic acid molecules (OLEA), were synthesized with controlled size, shape and surface chemistry by using colloidal routes. They were investigated for application as coating materials for preserving architectural stone of monumental and archaeological interest, in consideration of their self-cleaning and protection properties. For this purpose, two different deposition techniques, namely casting and dipping, were tested for the application of a nanocrystal dispersion on a defined stone type, as a relevant example of porous calcarenites, namely the Pietra Leccese, a building stone widely used in monuments and buildings of cultural and historic interest of the Apulia region (Italy). The physical properties of the stone surface were investigated before and after the treatment with the prepared nanostructured materials. In particular, colour, wettability, water transfer properties and stability of the coating were monitored as a function of time and of the application method. The self-cleaning properties of the TiO2 NRs coated surfaces were tested under simulated and real solar irradiation. The obtained results were discussed in the light of the specific surface chemistry and morphology of TiO2 NRs, demonstrating the effectiveness of TiO2 NRs as an active component in formulations for stone protection.

Rock fabric heterogeneity and its influence on the petrophysical properties of a building limestone: Lede stone (Belgium) as an example

Lede stone is an important historical stone in Belgium, with many ceased and disappeared historical quarries. Owing to its geological nature, this stone exhibits considerable variation in petrophysical properties. Three macroscopical different facies from the solely remaining quarry area in Balegem (Belgium) were profoundly characterized for their pore network properties and petrophysical properties. The pore network was exhaustively studied combining water imbibition under vacuum, mercury intrusion porosimetry and X-ray computed microtomography. The three facies not only have a strong difference in total porosity, but also differ in terms of pore connectivity and pore size distribution, linked to the variability in microfacies. This has profound implications on the water transfer properties such as atmospheric water absorption, capillary water absorption, omnidirectional drying and water vapor resistance. The petrophysical behavior is illustrated with a salt ageing test. The results can be used for restoration and conservation of Lede stone in the built cultural heritage.

Measuring the Hygroscopic Properties of Porous Media in Transient Regime. From the Material Level to the Whole Building HAM Simulation of a Coated Room

Moisture level inside buildings is a key factor influencing the durability of construction, indoor air quality, thermal comfort and energy performance. Numerical simulation can be used to predict the hygric inertia of a room, but reliable material data are needed as inputs for the model.Although the advancement of numerical models for whole building HAM (Heat Air and Moisture) transfer, a general need for more experimental data able to quantify the hygroscopic performance of porous building material remains. Recent benchmark data for validating 1-D HAM simulation models proposed in international projects are based on numerical and analytical data, while well-documented and accurate data are scarce. In IEA Annex 41 new numerical models have been implemented and used to simulate the HAM interaction between indoor air and hygroscopic materials during transient changes in indoor humidity due to internal moisture gains. Some experimental data obtained in dynamic humidity regime are presented in this study. The goal is to validate models that represent the moisture buffering of hygroscopic materials in contact with indoor air,.In order to fit the experimental data with numerical simulation and to determine the most influencing hygroscopic material properties in HAM modeling, a sensitivity analysis on the numerical fitting of measured properties relevant for indoor moisture buffering, such as the water vapour permeability and the sorption isotherm was carried out. Material data have been monitored using a climate chamber device especially designed for this purpose. In Italian buildings, especially dwellings, walls are very often plastered with gypsum plaster for levelling purposes. The gypsum plaster is generally covered with waterborne wall paint for decoration which represents a barrier for the water absorption or desorption. In order to assess the hygric performance of a room in real conditions, the influence of the water transfer properties of the painted gypsum on the whole building HAM dynamic simulation is assessed considering both an uncoated and a coated room using a waterborne paint.

The Influence of Coatings on the Environmental Hygric Inertia of Plastered Rooms

In Italian buildings, especially dwellings, walls are very often plastered with gypsum plaster for levelling purposes. The gypsum plaster is generally covered with waterborne wall paint for decoration which represents a barrier for the water absorption or desorption. To know the hygric performance of a room in such real conditions, the water transfer properties of the painted gypsum must be known. Wall paints can be roughly divided into waterborne and solvent borne paints. Waterborne wall paints are increasingly being used for their low odour and fast environmental friendly drying. The newer waterborne paints are based on aqueous dispersions of synthetic vinyl-type binders, such as polyvinylacetate or polyvinylpropionate (co-)polymers, and acrylic polymers. Moreover, paints containing volatile organic components have recently been prohibited by the European Commission for professional indoor use. The pressure to reduce volatile organic components and the industrial trend towards friendlier products with low toxicity of the product formulation led to the current expansion of waterborne types of coating. In building physics literature, knowledge is lacking about the moisture transfer properties of waterborne wall paints. Also the behavior of painted substrates has not been examined sufficiently. The role of the paint constituents in the moisture transfer properties is unclear. This lack of knowledge is partly caused by the lack of simple measuring techniques. Also the moisture behavior of the gypsum plays an important role in controlling the relative humidity, as the experimental activity in the paper for measuring its hygroscopic properties (Moisture Buffer Value) highlights. Painting gypsum is not done to prevent deterioration of the substrate as usually done for wood; gypsum is mainly painted for decorative reasons: this can also be a means to control the moisture transfer properties of the gypsum. Anyway, aim of the present study is not the numerical modelling or measuring of waterborne paints, but their influence once applied to the gypsum substrate, of which the hygroscopic properties where calculated when coated and uncoated. The numerical simulation using an whole building HAM-transfer model is then used to simulate the hygroscopic performance of a room in different conditions.

Reduction of Oil Uptake in Deep Fat Fried Falafel

Albert et al. experimented 11 hydrocolloid materials including gelatin, gellan gum, k-carrageenankonjac-blend, locust bean gum, methyl cellulose (MC), microcrystalline cellulose, pectin (three types), sodium caseinate, soy protein isolate (SPI), vital wheat gluten, and whey protein isolate (WPI). These materials were compared for their film forming ability and suitability for fried foods, water and fat transfer properties.