scholarly journals Steady-State Water Drainage by Oxygen in Anodic Porous Transport Layer of Electrolyzers: A 2D Pore Network Study

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 362 ◽  
Author(s):  
Haashir Altaf ◽  
Nicole Vorhauer ◽  
Evangelos Tsotsas ◽  
Tanja Vidaković-Koch
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Network Model ◽  
Phase Interface ◽  
Pore Network ◽  
Transport Layer ◽  
Pore Network Model ◽  
Network Simulations ◽  
The Impact

Recently, pore network modelling has been attracting attention in the investigation of electrolysis. This study focuses on a 2D pore network model with the purpose to study the drainage of water by oxygen in anodic porous transport layers (PTL). The oxygen gas produced at the anode catalyst layer by the oxidation of water flows counter currently to the educt through the PTL. When it invades the water-filled pores of the PTL, the liquid is drained from the porous medium. For the pore network model presented here, we assume that this process occurs in distinct steps and applies classical rules of invasion percolation with quasi-static drainage. As the invasion occurs in the capillary-dominated regime, it is dictated by the pore structure and the pore size distribution. Viscous and liquid film flows are neglected and gravity forces are disregarded. The curvature of the two-phase interface within the pores, which essentially dictates the invasion process, is computed from the Young Laplace equation. We show and discuss results from Monte Carlo pore network simulations and compare them qualitatively to microfluidic experiments from literature. The invasion patterns of different types of PTLs, i.e., felt, foam, sintered, are compared with pore network simulations. In addition to this, we study the impact of pore size distribution on the phase patterns of oxygen and water inside the pore network. Based on these results, it can be recommended that pore network modeling is a valuable tool to study the correlation between kinetic losses of water electrolysis processes and current density.

scholarly journals Pore network model of primary freeze drying

2018 ◽  
Author(s):  
Nicole Vorhauer ◽  
P. Först ◽  
H. Schuchmann ◽  
E. Tsotsas
Keyword(s):  
Heat Transfer ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Network Model ◽  
Pore Network ◽  
Vapor Transport ◽  
Pore Network Model ◽  
Sublimation Front ◽  
The Impact

The pore scale progression of the sublimation front during primary freeze drying depends on the local vapor transport and the local heat transfer as well. If the pore space is size distributed, vapor and heat transfer may spatially vary. Beyond that, the pore size distribution can substantially affect the physics of the transport mechanisms if they occur in a transitional regime. Exemplarily, if the critical mean free path is locally exceeded, the vapor transport regime passes from viscous flow to Knudsen diffusion. At the same time, the heat transfer is affected by the local ratio of pore space to the solid skeleton. The impact of the pore size distribution on the transitional vapor and heat transfer can be studied by pore scale models such as the pore network model. As a first approach, we present a pore network model with vapor transport in the transitional regime between Knudsen diffusion and viscous flow at constant temperature in the dry region. We demonstrate the impact of pore size distribution, temperature and pressure on the vapor transport regimes. Then we study on the example of a 2D square lattice, how the presence of micro and macro pores affects the macroscopic progression of the sublimation front.   Keywords: pore size distribution; transitional vapor transport; pore network model; fractured sublimation front.

scholarly journals Pore Network Analysis of Zone Model for Porous Media Drying

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yuan Yuejin ◽  
Zhao Zhe ◽  
Nie Junnan ◽  
Xu Yingying
Keyword(s):  
Porous Media ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Phase Distribution ◽  
Pore Network ◽  
Pore Network Model ◽  
Zone Model ◽  
Drying Process ◽  
Isothermal Drying

In view of the fact that the zone model for porous media drying cannot disclose the mechanism of liquid phase distribution effectively, a pore network model for the slow isothermal drying process of porous media was developed by applying the theories of pore network drying and transport-process, which fused the physical parameters of porous media, such as porosity, pore mean diameter, and pore size distribution into the model parameters, and a sand bed drying experiment was conducted to verify the validity of this model. The experiment and simulation results indicate that the pore network model could explain the slow isothermal drying process of porous media well. The pore size distributions of porous media have a great effect on the liquid phase distribution of the drying process. The dual-zone model is suitable for the porous media whose pore size distribution obeys Gaussian distribution, while the three-zone model is suitable for the porous media whose pore size distribution obeys the lognormal distribution when the drying analysis of porous media is conducted.

scholarly journals Pore Network Simulation of Gas-Liquid Distribution in Porous Transport Layers

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 558 ◽  
Author(s):  
Nicole Vorhauer ◽  
Haashir Altaf ◽  
Evangelos Tsotsas ◽  
Tanja Vidakovic-Koch
Keyword(s):  
Porous Media ◽  
Water Supply ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Network Models ◽  
Pore Network ◽  
Liquid Films ◽  
Transport Layer ◽  
Liquid Clusters

Pore network models are powerful tools to simulate invasion and transport processes in porous media. They are widely applied in the field of geology and the drying of porous media, and have recently also received attention in fuel cell applications. Here we want to describe and discuss how pore network models can be used as a prescriptive tool for future water electrolysis technologies. In detail, we suggest in a first approach a pore network model of drainage for the prediction of the oxygen and water invasion process inside the anodic porous transport layer at high current densities. We neglect wetting liquid films and show that, in this situation, numerous isolated liquid clusters develop when oxygen invades the pore network. In the simulation with narrow pore size distribution, the volumetric ratio of the liquid transporting clusters connected between the catalyst layer and the water supply channel is only around 3% of the total liquid volume contained inside the pore network at the moment when the water supply route through the pore network is interrupted; whereas around 40% of the volume is occupied by the continuous gas phase. The majority of liquid clusters are disconnected from the water supply routes through the pore network if liquid films along the walls of the porous transport layer are disregarded. Moreover, these clusters hinder the countercurrent oxygen transport. A higher ratio of liquid transporting clusters was obtained for greater pore size distribution. Based on the results of pore network drainage simulations, we sketch a new route for the extraction of transport parameters from Monte Carlo simulations, incorporating pore scale flow computations and Darcy flow.

Trapping patterns during capillary displacements in disordered media

2022 ◽  
Vol 933 ◽  
Author(s):  
Fanli Liu ◽  
Moran Wang
Keyword(s):  
Numerical Simulations ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Disordered Media ◽  
Pore Geometry ◽  
Control Parameters ◽  
Pore Throat ◽  
The Impact ◽  
Theoretical Analyses

We investigate the impact of wettability distribution, pore size distribution and pore geometry on the statistical behaviour of trapping in pore-throat networks during capillary displacement. Through theoretical analyses and numerical simulations, we propose and prove that the trapping patterns, defined as the percentage and distribution of trapped elements, are determined by four dimensionless control parameters. The range of all possible trapping patterns and how the patterns are dependent on the four parameters are obtained. The results help us to understand the impact of wettability and structure on trapping behaviour in disordered media.

scholarly journals Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2247
Author(s):  
Claire Delaroa ◽  
René Fulchiron ◽  
Eric Lintingre ◽  
Zoé Buniazet ◽  
Philippe Cassagnau
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
High Density Polyethylene ◽  
Mercury Porosimetry ◽  
High Density ◽  
Organic Binder ◽  
Molten State ◽  
Homogeneous Dispersion ◽  
The Impact

The impact of polypropylene and high-density polyethylene backbone binders on the structure of organic matrix, feedstock, and ceramic parts is investigated in terms of morphology in this paper. The miscibility of wax with polyethylene and polypropylene is investigated in the molten state via a rheological study, revealing wax full miscibility with high-density polyethylene and restricted miscibility with polypropylene. Mercury porosimetry measurements realized after wax extraction allow the characterization of wax dispersion in both neat organic blends and zirconia filled feedstocks. Miscibility differences in the molten state highly impact wax dispersion in backbone polymers after cooling: wax is preferentially located in polyethylene phase, while it is easily segregated from polypropylene phase, leading to the creation of large cracks during solvent debinding. The use of a polyethylene/polypropylene ratio higher than 70/30 hinders wax segregation and favors its homogeneous dispersion in organic binder. As zirconia is added to organic blends containing polyethylene, polypropylene, and wax, the pore size distribution created by wax extraction is shifted towards smaller pores. Above zirconia percolation at 40 vol%, the pore size distribution becomes sharp attesting of wax homogeneous dispersion. As the PP content in the organic binder decreases from 100% to 0%, the pore size distribution is reduced of 30%, leading to higher densification ability. In order to ensure a maximal densification of the final ceramic, polyethylene/polypropylene ratios with a minimum content of 70% of high-density polyethylene should be employed.

Analysis of Water Agglomeration Inside the GDL Using a Pore-Network Model

2010 ◽  
Author(s):  
Mehdi Shahraeeni ◽  
Mina Hoorfar
Keyword(s):  
Pore Size ◽  
Analytical Model ◽  
Network Model ◽  
Transient Response ◽  
Pore Network ◽  
Pore Network Model ◽  
Size Distributions ◽  
Water Motion ◽  
Pore Size Distributions

This article investigates the transient response of water motion inside the GDLs having different pore size distributions. A pore-network model is developed and applied to the problem. The results of the simulation are in agreement with the analytical model available in the literature.

Porosity and pore size distribution of shales: a case study of the Carynginia Formation, Perth Basin, Western Australia

2017 ◽  
Vol 57 (2) ◽  
pp. 660
Author(s):  
M. Nadia Testamanti ◽  
Reza Rezaee ◽  
Jie Zou
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Gas Adsorption ◽  
Pore Network ◽  
Pore Sizes ◽  
Wide Range ◽  
Pore Characterisation ◽  
Shale Reservoirs ◽  
Mercury Injection Capillary Pressure

The evaluation of the gas storage potential of shale reservoirs requires a good understanding of their pore network. Each of the laboratory techniques used for pore characterisation can be applied to a specific range of pore sizes; but if the lithology of the rock is known, usually one suitable method can be selected to investigate its pore system. Shales do not fall under any particular lithological classification and can have a wide range of minerals present, so a combination of at least two methods is typically recommended for a better understanding of their pore network. In the laboratory, the Low-Pressure Nitrogen Gas Adsorption (LP-N2-GA) technique is typically used to examine micropores and mesopores, and Mercury Injection Capillary Pressure (MICP) tests can identify pore throats larger than 3 nm. In contrast, a wider range of pore sizes in rock can be screened with Nuclear Magnetic Resonance (NMR), either in laboratory measurements made on cores or through well logging, provided that the pores are saturated with a fluid. The pore network of a set of shale core samples from the Carynginia Formation was investigated using a combination of laboratory methods. The cores were studied using the NMR, LP-N2-GA and MICP techniques, and the experimental porosity and pore size distribution results are presented. When NMR results were calibrated with MICP or LP-N2-GA measurements, then the pore size distribution of the shale samples studied could be estimated.

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