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.

Numerical and Experimental Pore Network Study on Slowly Isothermal Drying of Real Porous Media

2012 ◽  
Vol 538-541 ◽  
pp. 538-541 ◽  
Author(s):  
Ying Ying Xu ◽  
Yue Ding Yuan ◽  
Yue Jin Yuan ◽  
Xin An Dang ◽  
Xiang Dong Liu
Keyword(s):  
Porous Media ◽  
Size Distribution ◽  
Pore Network ◽  
Pore Network Model ◽  
Physical Parameters ◽  
Model Parameters ◽  
Drying Process ◽  
Object A ◽  
Isothermal Drying ◽  
Simulated Object

Taking the sand bed as the simulated object, a pore network model for drying of real porous media is developed by applying the invasion percolation theory and transport process principle, which fused the physical parameters of sand bed, such as porosity, pore mean diameter, pore size distribution, into the model parameters. The experiment and simulation results indicated that this model could explain the drying process of sand bed well. The throat size distribution has a great effect on the drying process.

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.

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.

A Pore Network Model for Drying Processes in Porous Media

2001 ◽  
Author(s):  
A. G. Yiotis ◽  
A. K. Stubos ◽  
A. G. Boudouvis ◽  
Y. C. Yortsos
Keyword(s):  
Porous Media ◽  
Network Model ◽  
Gas Flow ◽  
Phase Distribution ◽  
Pore Network ◽  
Pore Network Model ◽  
Gas Phases ◽  
Drying Rates ◽  
Purge Gas ◽  
Isothermal Drying

Abstract A pore network model for the drying of capillary porous media is presented in this work. The model accounts for various processes at the pore scale including evaporation of a volatile liquid, mass transfer of the vapors by advection and diffusion in the gas phase and viscous flow in the liquid and gas phases. Both viscous and capillary forces at the liquid menisci in pore throats are also modeled. We consider isothermal drying in a rectilinear horizontal geometry, with no flow conditions in all but one boundary, at which a purge gas is injected at a constant rate. Drying rates, phase distribution and concentration patterns are reported as a function of time and the gas flow rate. We also refer to the evolution of trapped liquid clusters.

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.

Sign in / Sign up

Export Citation Format

Share Document