scholarly journals Development of Predictive Techniques for Estimating Liquid Water-Hydrate Equilibrium of Water-Hydrocarbon System

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
Amir H. Mohammadi ◽  
Dominique Richon
Keyword(s):  
Experimental Data ◽  
Gas Hydrates ◽  
Liquid Water ◽  
Pure Water ◽  
Neural Network Algorithm ◽  
Water Fugacity ◽  
Independent Experimental Data ◽  
Pure Hydrocarbon ◽  
Coefficient Method ◽  
Artificial Neural Network Algorithm

In this communication, we review recent studies by these authors for modeling the -H equilibrium. With the aim of estimating the solubility of pure hydrocarbon hydrate former in pure water in equilibrium with gas hydrates, a thermodynamic model is introduced based on equality of water fugacity in the liquid water and hydrate phases. The solid solution theory of Van der Waals-Platteeuw is employed for calculating the fugacity of water in the hydrate phase. The Henry's law approach and the activity coefficient method are used to calculate the fugacities of the hydrocarbon hydrate former and water in the liquid water phase, respectively. The results of this model are successfully compared with some selected experimental data from the literature. A mathematical model based on feed-forward artificial neural network algorithm is then introduced to estimate the solubility of pure hydrocarbon hydrate former in pure water being in equilibrium with gas hydrates. Independent experimental data (not employed in training and testing steps) are used to examine the reliability of this algorithm successfully.

Calculation of water content in water–methane system

2010 ◽  
Vol 75 (3) ◽  
pp. 257-274
Author(s):  
Petr Voňka ◽  
Monika Hubková ◽  
Vít Meistr
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Water Content ◽  
Liquid Water ◽  
Pure Water

Two methods to calculate the water content of water (1)–methane (2) system in the liquid–gas and ice–gas regions at temperatures from 253 to 373 K are proposed and tested in this work. Both are based on the assumption that the influence of methane solubility in liquid water on the calculated water content can be neglected (i.e., only pure water is considered in the liquid phase). A survey of experimental data is also given.

scholarly journals An Accurate Model to Calculate CO2 Solubility in Pure Water and in Seawater at Hydrate–Liquid Water Two-Phase Equilibrium

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 393
Author(s):  
Mengyao Di ◽  
Rui Sun ◽  
Lantao Geng ◽  
Wanjun Lu
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Liquid Water ◽  
Model Comparison ◽  
Pure Water ◽  
Co2 Storage ◽  
Co2 Solubility ◽  
Two Phase ◽  
Hydrate Phase ◽  
Water Equilibrium

Understanding of CO2 hydrate–liquid water two-phase equilibrium is very important for CO2 storage in deep sea and in submarine sediments. This study proposed an accurate thermodynamic model to calculate CO2 solubility in pure water and in seawater at hydrate–liquid water equilibrium (HLWE). The van der Waals–Platteeuw model coupling with angle-dependent ab initio intermolecular potentials was used to calculate the chemical potential of hydrate phase. Two methods were used to describe the aqueous phase. One is using the Pitzer model to calculate the activity of water and using the Poynting correction to calculate the fugacity of CO2 dissolved in water. Another is using the Lennard–Jones-referenced Statistical Associating Fluid Theory (SAFT-LJ) equation of state (EOS) to calculate the activity of water and the fugacity of dissolved CO2. There are no parameters evaluated from experimental data of HLWE in this model. Comparison with experimental data indicates that this model can calculate CO2 solubility in pure water and in seawater at HLWE with high accuracy. This model predicts that CO2 solubility at HLWE increases with the increasing temperature, which agrees well with available experimental data. In regards to the pressure and salinity dependences of CO2 solubility at HLWE, there are some discrepancies among experimental data. This model predicts that CO2 solubility at HLWE decreases with the increasing pressure and salinity, which is consistent with most of experimental data sets. Compared to previous models, this model covers a wider range of pressure (up to 1000 bar) and is generally more accurate in CO2 solubility in aqueous solutions and in composition of hydrate phase. A computer program for the calculation of CO2 solubility in pure water and in seawater at hydrate–liquid water equilibrium can be obtained from the corresponding author via email.

scholarly journals Measurement of the sound velocity of shock compressed water

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hua Shu ◽  
Jiangtao Li ◽  
Yucheng Tu ◽  
Junjian Ye ◽  
Junyue Wang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Equation Of State ◽  
Liquid Water ◽  
Diamond Anvil Cell ◽  
Quantum Molecular Dynamics ◽  
Laser Shock ◽  
Diamond Anvil ◽  
Ionization Processes ◽  
Sound Velocities

AbstractThe sound velocities of water in the Hugoniot states are investigated by laser shock compression of precompressed water in a diamond anvil cell. The obtained sound velocities in the off-Hugoniot region of liquid water at precompressed conditions are used to test the predictions of quantum molecular dynamics (QMD) simulations and the SESAME equation-of-state (EOS) library. It is found that the prediction of QMD simulations agrees with the experimental data while the prediction of SESAME EOS library underestimates the sound velocities probably due to its improper accounting for the ionization processes.

scholarly journals Modelling Macrophage Infiltration into Avascular Tumours

2002 ◽  
Vol 4 (1) ◽  
pp. 21-38 ◽  
Author(s):  
C. E. Kelly ◽  
R. D. Leek ◽  
H. M. Byrne ◽  
S. M. Cox ◽  
A. L. Harris ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Spatial Structure ◽  
Random Motion ◽  
Numerical Results ◽  
Macrophage Infiltration ◽  
Numerical Techniques ◽  
Model Predictions ◽  
Independent Experimental Data

In this paper a mathematical model that describes macrophage infiltration into avascular tumours is presented. The qualitative accuracy of the model is assessed by comparing numerical results with independent experimental data that describe the infiltration of macrophages into two types of spheroids: chemoattractant-producing (hepa-1) and chemoattractant-deficient (or C4) spheroids. A combination of analytical and numerical techniques are used to show how the infiltration pattern depends on the motility mechanisms involved (i.e. random motion and chemotaxis) and to explain the observed differences in macrophage infiltration into the hepa-1 and C4 spheroids. Model predictions are generated to show how the spheroid's size and spatial structure and the ability of its constituent cells influence macrophage infiltration. For example, chemoattractant-producing spheroids are shown to recruit larger numbers of macrophages than chemoattractant-deficient spheroids of the same size and spatial structure. The biological implications of these results are also discussed briefly.

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