Vertical water transport model in concrete based on the coupled effects of the capillarity, gravity and evaporation

Reducing the water crossover from anode to cathode is an important goal for direct methanol fuel cell (DMFC) technology, especially if highly concentrated methanol fuel is to be used. A well-documented way to reduce this water loss to the cathode side is by using a hydrophobic cathode microporous layer (MPL). Recently, however, it has been demonstrated that in addition to a cathode MPL, the use of a hydrophobic anode MPL further reduces the water loss to the cathode. In this work, we use a two-phase transport model that accounts for capillary induced liquid flow in porous media to explain physically how a hydrophobic anode MPL acts to control the net water transport from anode to cathode. Additionally, we perform a case study and show that a thicker, more hydrophobic anode MPL with lower permeability is most effective in controlling the net water transport from anode to cathode.

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Leaf cell wall properties and stomatal density influence oxygen isotope enrichment of leaf water

10.1101/2020.10.15.341693 ◽

2020 ◽

Author(s):

Patrick Ellsworth ◽

Patricia Ellsworth ◽

Rachel Mertz ◽

Nuria Koteyeva ◽

Asaph B. Cousins

Keyword(s):

Cell Wall ◽

Water Transport ◽

Water Movement ◽

Transport Model ◽

Stomatal Density ◽

Oxygen Isotopic Composition ◽

Cell Wall Composition ◽

Leaf Water ◽

Suberin Lamellae ◽

The Difference

AbstractOxygen isotopic composition (Δ18OLW) of leaf water can help improve our understanding of how anatomy interacts with physiology to influence leaf water transport. Leaf water isotope models of Δ18OLW such as the Péclet effect model have been developed to predict Δ18OLW, and it incorporates transpiration rate (E) and the mixing length between unenriched xylem water and enriched mesophyll water, which can occur in the mesophyll (Lm) or veins (Lv). Here we used two cell wall composition mutants grown under two light intensities and RH to evaluate the effect of cell wall composition on Δ18OLW. In maize (Zea mays), the compromised ultrastructure of the suberin lamellae in the bundle sheath of the ALIPHATIC SUBERIN FERULOYL TRANSFERASE mutant (Zmasft) reduced barriers to apoplastic water movement, resulting in higher E and Lv and, consequently, lower Δ18OLW. In cellulose synthase-like F6 (Cslf6) mutants and wildtype of rice (Oryza sativa), the difference in Δ18OLW in plants grown under high and low growth light intensity co-varied with their differences in stomatal density. These results show that cell wall composition and stomatal density influence Δ18OLW by altering the Péclet effect and that stable isotopes can facilitate the development of a physiologically and anatomically explicit water transport model.

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Review of "Liquid water infiltration into a layered snowpack: evaluation of a 3D water transport model with laboratory experiments"

10.5194/hess-2017-200-rc2 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Water Transport ◽

Liquid Water ◽

Laboratory Experiments ◽

Transport Model ◽

Water Infiltration

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Quantitative study of water transport during the hydrolysis of polymer coatings exposed to water vapor

Journal of Materials Research ◽

10.1557/jmr.2003.0316 ◽

2003 ◽

Vol 18 (9) ◽

pp. 2268-2275 ◽

Cited By ~ 5

Author(s):

Sanboh Lee ◽

Tinh Nguyen ◽

Eric Byrd ◽

Jon Martin

Keyword(s):

Water Transport ◽

Transport Model ◽

Hydrolytic Degradation ◽

Water Concentration ◽

High Water ◽

Polymer Coatings ◽

Coating Film ◽

Complex Process ◽

Quantitative Analyses ◽

Hydrolysis Of

Thermoset acrylic–melamine resins are widely used for automobile exterior coatings. These materials are formulated by reacting an acrylic polyol with an alkylated melamine. Because the reactions are reversible, acrylic–melamine coatings tend to hydrolyze during exposures in moist environments. During hydrolysis, water in the coating film is consumed. To keep the moisture content in the film in equilibrium, water must be transported from regions of high water concentration to regions of low water concentration. An approach based on Fourier transform infrared (FTIR) spectroscopy analysis of the coating degradation fitted to a transport model is presented to estimate the diffusion coefficients and velocities of water transport during the hydrolysis of an acrylic–melamine coating exposed to different relative humidities (RHs). Theoretical prediction agreed well with the experimental FTIR data of coating hydrolytic degradation. Generally, both the diffusion coefficient and velocity of water transport in the coating increased with increasing RH. Since water transport resulting from the hydrolysis reactions is a very slow and complex process, the approach presented here provides a viable means for obtaining valuable data for quantitative analyses of coating hydrolytic degradation at different RHs.

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Simulation of Water Transport in Heated Rock Salt

MRS Proceedings ◽

10.1557/proc-50-577 ◽

1985 ◽

Vol 50 ◽

Cited By ~ 1

Author(s):

M. Schlich ◽

N. Jockwer

Keyword(s):

Water Transport ◽

Rock Salt ◽

Fluid Transport ◽

Transport Model ◽

Adsorbed Water ◽

Experimental Investigations ◽

Simulation Studies ◽

Water Layers ◽

Computer Simulation Studies ◽

Front Model

AbstractThis paper summarizes computer simulation studies on water transport in German rock salt. Based on JOCKWERS's experimental investigations on water content and water liberation, the object of these studies was to select a water transport model, that matches the water inflow which was measured in some heater experiments in the Asse Salt Mine. The main re-sult is, that an evaporation front model, with Knudsen-type vapor transport combined with fluid transport by thermal expansion of the adsorbed water layers in the non evaporated zone, showed the best agreement with experi-mental evidence.

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A Method to Predict Water Recovery Rate in the Collection and Froth Zone of Flotation Systems

Minerals ◽

10.3390/min10070630 ◽

2020 ◽

Vol 10 (7) ◽

pp. 630

Author(s):

Jose Martinez ◽

Miguel Maldonado ◽

Leopoldo Gutierrez

Keyword(s):

Water Transport ◽

Recovery Rate ◽

Transport Model ◽

Bubble Column ◽

Fundamental Result ◽

Water Recovery ◽

Foam Layer ◽

Operating Variables ◽

Single Function ◽

Water Rate

This paper describes a method to predict water recovery rate into and through the foam in a bubble column operating under different gas rates, froth depths, and frother types and concentrations. Three frothers were considered: Metil Isobutil Carbinol (MIBC), a proprietary blend of alcohols, aldehydes, and esters commercialized under the name PINNACLE® 9891, and a PGE-based Dow Froth 1012 (DF1012). The water rate entering into the froth (foam) layer from the bubbly (collection) zone was estimated as the water rate overflowing the column when operating at a thin stable foam layer, i.e., 0.5 cm. It was observed that the rate at which water entered into the froth phase could be modelled as a unique linear function of the gas holdup below the froth, regardless of the frother chemistry. This is a fundamental result not previously found in the literature that also facilitates the calculation of the froth zone water recovery for deeper froths. The water recovery in the froth was found to be an inverse logarithmic function of the average liquid residence time in the froth. Although the same trend was observed for the three frothers tested, they did not converge into a single function, which suggests that frother chemistry plays a role in determining froth structure and then needs to be incorporated when modeling water transport in the froth. Finally, the water overflow rate calculated as the product of the water rate into the froth and froth water recovery predicted the actual measured values fairly well. The water transport model here proposed provides a simple representation of the interactions between collection and froth zone and its relation to easily measure operating variables.

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Characterization and modelling of air humidification in Fuel Cell System for transport sector

E3S Web of Conferences ◽

10.1051/e3sconf/202233406009 ◽

2022 ◽

Vol 334 ◽

pp. 06009

Author(s):

Amedeo Grimaldi ◽

Lorenzo Villa ◽

Andrea Baricci ◽

Stefano De Antonellis ◽

Claudio Oldani ◽

...

Keyword(s):

Water Transport ◽

Transport Model ◽

Cell System ◽

Operating Conditions ◽

Transport Sector ◽

Counter Flow ◽

Physical Description ◽

Vapor Permeation ◽

Individual Contributions ◽

Transfer Properties

A model for the physical description of water transport through steady-state permeation and dynamic sorption within perfluoro-sulfonic acid (PFSA) membranes has been developed. A broad experimental campaign is conducted on several membranes, belonging to Aquivion class, varying both in thickness and equivalent weight (EW). The experimental data have been used to calibrate and validate water transport model and to find correlations for mass-transfer properties in low-EW PFSA membranes that describe consistently both water vapor permeation and sorption. It has been possible to identify individual contributions to mass transport resistance and to determine the optimal configuration and materials of a full-scale counter-flow membrane humidifier under a set of specific operating conditions.

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Review “Liquid water infiltration into a layered snowpack: evaluation of a 3D water transport model with laboratory experiments” by Hiroyuki Hirashima et al.

10.5194/hess-2017-200-rc1 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Water Transport ◽

Liquid Water ◽

Laboratory Experiments ◽

Transport Model ◽

Water Infiltration

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A Simplified Procedure to Determine the Optimal Rate of Freezing Biological Systems

Journal of Biomechanical Engineering ◽

10.1115/1.1865213 ◽

2004 ◽

Vol 127 (2) ◽

pp. 295-300 ◽

Cited By ~ 21

Author(s):

Sreedhar Thirumala ◽

Ram V. Devireddy

Keyword(s):

Cooling Rate ◽

Water Transport ◽

Transport Model ◽

Biological Systems ◽

Optimal Rate ◽

Water Volume ◽

Extensive Investigation ◽

Cell Level ◽

Initial Water ◽

Simplified Procedure

The effect of several cell-level parameters on the predicted optimal cooling rate Bopt of an arbitrary biological system has been studied using a well-defined water transport model. An extensive investigation of the water transport model revealed three key cell level parameters: reference permeability of the membrane to water Lpg, apparent activation energy ELp, and the ratio of the available surface area for water transport to the initial volume of intracellular water (SA∕WV). We defined Bopt as the “highest” cooling rate at which a predefined percent of the initial water volume is trapped inside the cell (values ranging from 5% to 80%) at a predefined end temperature (values ranging from −5°C to −40°C). Irrespective of the choice of the percent of initial water volume trapped and the end temperature, an exact and linear relationship exists between Lpg,SA∕WV, and Bopt. However, a nonlinear and inverse relationship is found between ELp and Bopt. Remarkably, for a variety of biological systems a comparison of the published experimentally determined values of Bopt agreed quite closely with numerically predicted Bopt values when the model assumed 5% of initial water is trapped inside the cell at a temperature of −15°C. This close agreement between the experimental and model predicted optimal cooling rates is used to develop a generic optimal cooling rate chart and a generic optimal cooling rate equation that greatly simplifies the prediction of the optimal rate of freezing of biological systems.

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