DYNAMICS OF SIMPLE FLUIDS CONFINED IN CYLINDRICAL PORE: EFFECT OF PORE SIZE

2005 ◽  
Vol 04 (01) ◽  
pp. 305-315 ◽  
Author(s):  
HYUNGJUN KIM ◽  
CHUL HEE CHO ◽  
EOK KYUN LEE
Keyword(s):  
Pore Size ◽  
Particle Diameter ◽  
Simulation Method ◽  
The Self ◽  
Dynamics Simulation ◽  
Axial Component ◽  
Cylindrical Pore ◽  
Self Diffusion ◽  
Wide Range ◽  
Wall Interaction

We study the thermodynamic and dynamical properties of Weeks–Chandler–Anderson (WCA) fluids confined in a cylindrical pore by means of a canonical molecular dynamics simulation method. The pore model is an infinitely long cylinder consisted of a thermal wall and mimics a typical carbon nanotube. The thermodynamic properties are obtained for relatively high density fluids over a wide range of pore diameters at a given temperature. The size dependence of the self-diffusion coefficients in the cylindrical pore is also investigated. It is found that, as the pore diameter decreases, the potential energy and axial component of the pressure exhibit a sharp rise and the self-diffusion coefficient decreases. The observed behaviors can be understood in terms of the geometrical confinement and attenuation of transport induced by dispersive fluid-wall interaction. In addition, anomalous diffusion is observed at the pore size corresponding to twice the particle diameter.

Self-diffusion of lignite/water under different temperatures and pressure: A molecular dynamics study

2016 ◽  
Vol 30 (01) ◽  
pp. 1550253 ◽  
Author(s):  
Xinjian Liu ◽  
Yu Jin ◽  
Congliang Huang ◽  
Jingfeng He ◽  
Zhonghao Rao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Water System ◽  
Simulation Method ◽  
The Self ◽  
Dynamics Simulation ◽  
Low Rank ◽  
Self Diffusion ◽  
Change Mechanism ◽  
Different Temperatures ◽  
Temperature And Pressure

Temperature and pressure have direct and remarkable implications for drying and dewatering effect of low rank coals such as lignite. To understand the microenergy change mechanism of lignite, the molecular dynamics simulation method was performed to study the self-diffusion of lignite/water under different temperatures and pressure. The results showed that high temperature and high pressure can promote the diffusion of lignite/water system, which facilitates the drying and dewatering of lignite. The volume and density of lignite/water system will increase and decrease with temperature increasing, respectively. Though the pressure within simulation range can make lignite density increase, the increasing pressure showed a weak impact on variation of density.

c , T-Dependence of the Self Diffusion in Concentrated Aqueous Sucrose Solutions

1994 ◽  
Vol 49 (3-4) ◽  
pp. 258-264 ◽  
Author(s):  
D. Girlich ◽  
H.-D. Lüdemann ◽  
C. Buttersack ◽  
K. Buchholz
Keyword(s):  
Field Gradient ◽  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
The Self ◽  
Water Molecules ◽  
Pulsed Field Gradient Nmr ◽  
Pulsed Field ◽  
Self Diffusion ◽  
Sucrose Solutions ◽  
Wide Range

The self diffusion coefficients D of the water molecules and of sucrose have been determined by the pulsed field gradient NMR technique over a wide range of temperatures and concentrations (cmax: 70% w/w suc.). All temperature dependencies can be fitted to a Vogel- Tammann-Fulcher equation. The isothermic concentration dependence of D for the sucrose is given by a simple exponential concentration dependence

Pore-size dependence of the self-diffusion of hexane in silica gels

2002 ◽  
Vol 116 (24) ◽  
pp. 10869-10876 ◽  
Author(s):  
J. Baumert ◽  
B. Asmussen ◽  
C. Gutt ◽  
R. Kahn
Keyword(s):  
Pore Size ◽  
Size Dependence ◽  
The Self ◽  
Silica Gels ◽  
Self Diffusion

scholarly journals Effect of mixed anions on the transport properties and performance of an ionic liquid-based electrolyte for lithium-ion batteries

2019 ◽  
Vol 91 (8) ◽  
pp. 1361-1381 ◽  
Author(s):  
Victor Chaudoy ◽  
Johan Jacquemin ◽  
François Tran-Van ◽  
Michaël Deschamps ◽  
Fouad Ghamouss
Keyword(s):  
Transport Properties ◽  
Lithium Ion Batteries ◽  
Salt Concentration ◽  
Lithium Salt ◽  
Nuclear Overhauser Effect ◽  
Lithium Ion ◽  
Activation Energies ◽  
The Self ◽  
Self Diffusion ◽  
Wide Range

Abstract In this work, the physical, transport and electrochemical properties of various electrolytic solutions containing the 1-propyl-1-methylpyrrolidinium bis[fluorosulfonyl]imide ([C3C1pyr][FSI]) mixed with the lithium bis[(trifluoromethyl)sulfonyl]imide (Li[TFSI]) over a wide range of compositions are reported as a function of temperature at atmospheric pressure. First, the ionicity, lithium transference number, and transport properties (viscosity and conductivity) as well as the volumetric properties (density and molar volume) were determined as a function of lithium salt concentration from 293 to 343 K. Second, the self-diffusion coefficient of each ion in solution was measured by nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradients (PFG). Moreover, an analysis of the collected nuclear Overhauser effect (NOE) data along with ab initio and COSMO-RS calculations was conducted to depict intra and intermolecular neighbouring within the electrolytic mixtures. Based on this analysis, and as expected, all activation energies increase with the Li[TFSI] concentration in solution, and all activation energies were determined from the self-diffusion data for all ions. Interestingly, regardless of the composition in solution, these activation energies were similar, except for those determined for the [FSI]− anion. The activation energy of [FSI]− self-diffusion relatively decreases compared to the other ions as the lithium salt concentration increases. Furthermore, the lithium transference was strongly affected by the lithium salt concentration, reaching an optimal value and an ionicity of approximately 50 % at a molality close to 0.75 mol · kg−1. Finally, these electrolytes were used in lithium-ion batteries (i.e. Li/NMC and LTO/NMC), demonstrating a clear relationship between the electrolyte formulation, its transport parameters and battery performance.

A Molecular Dynamics Simulation of Molten (Li-Rb)Cl Implying the Chemla Effect of Mobilities

1980 ◽  
Vol 35 (5) ◽  
pp. 493-499 ◽  
Author(s):  
Isao Okada ◽  
Ryuzo Takagi ◽  
Kazutaka Kawamura
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Diffusion Coefficients ◽  
Strong Correlation ◽  
Pair Correlation ◽  
The Self ◽  
Dynamics Simulation ◽  
Self Diffusion ◽  
Pure Salt ◽  
Dynamics Simulations

Abstract A new transport property, the self-exchange velocity (SEV) of neighbouring unlike ions, has been evaluated from molecular dynamics simulations of molten LiCl, RbCl and LiRbCl2 at 1100 K and the mixture at 750 K. From the increase of the SEV's in the order Rb+ (pure salt) <Li+ (mixture) < Rb+ (mixture) < Li+ (pure salt), it is conjectured that there is a strong correlation between the SEV’s and the internal mobilities. An interpretation of the Chemla effect in its dependence on temperature is given. The pair correlation functions and the self-diffusion coefficients are also calculated and discussed.

scholarly journals Molecular-Dynamics Simulation of Self-Diffusion of Molecular Hydrogen in X-Type Zeolite

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoming Du
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Mean Free Path ◽  
The Self ◽  
Dynamics Simulation ◽  
Pulse Field ◽  
Self Diffusion ◽  
Hydrogen Molecules ◽  
Dynamics Simulations

The self-diffusion of hydrogen in NaX zeolite has been studied by molecular-dynamics simulations for various temperatures and pressures. The results indicate that in the temperature range of 77–293 K and the pressure range of 10–2700 kPa, the self-diffusion coefficients are found to range from 1.61 × 10−9 m2·s−1to 3.66 × 10−8 m2·s−1which are in good agreement with the experimental values from the quasielastic neutron scattering (QENS) and pulse field gradients nuclear magnetic resonance (PFG NMR) measurements. The self-diffusion coefficients decrease with increasing pressure due to packing of sorbate-sorbate molecules which causes frequent collusion among hydrogen molecules in pores and increase with increasing temperature because increasing the kinetic energy of the gas molecules enlarges the mean free path of gas molecule. The activated energy for hydrogen diffusion determined from the simulation is pressure-dependent.

scholarly journals Cooperative CO2 adsorption promotes high CO2 adsorption density over wide optimal nanopore range

2017 ◽  
Vol 36 (1-2) ◽  
pp. 625-639 ◽  
Author(s):  
Lei Chen ◽  
Takumi Watanabe ◽  
Hirofumi Kanoh ◽  
Kenji Hata ◽  
Tomonori Ohba
Keyword(s):  
Porous Media ◽  
Specific Surface ◽  
Pore Size ◽  
Co2 Adsorption ◽  
High Capacity ◽  
Potential Wells ◽  
Cylindrical Pore ◽  
Cooperative Adsorption ◽  
Wide Range ◽  
Adsorption Density

Separation of CO2 based on adsorption, absorption, and membrane techniques is a crucial technology necessary to address current global warming issues. Porous media are essential for all these approaches and understanding the nature of the porous structure is important for achieving highly efficient CO2 adsorption. Porous carbon is considered to be a suitable porous media for investigating the fundamental mechanisms of CO2 adsorption, because of its simple morphology and its availability in a wide range of well-defined pore sizes. In this study, we investigated the dependence of CO2 adsorption on pore structures such as pore size, volume, and specific surface area. We also studied slit-shaped and cylindrical pore morphologies based on activated carbon fibers of 0.6–1.7 nm and carbon nanotubes of 1–5 nm, respectively, with relatively uniform structures. Porous media with larger specific surface areas gave higher CO2 adsorption densities than those of media having larger pore volumes. Narrower pores gave higher adsorption densities because of deep adsorption potential wells. However, at a higher pressure CO2 adsorption densities increased again in nanopores including micropores and small mesopores. The optimal pore size ranges of CO2 adsorption in the slit-shaped and cylindrical carbon pores were 0.4–1.2 and 1.0–2.0 nm, respectively, although a high adsorption density was only expected for the narrow carbon nanopores from adsorption potentials. The wider nanopore ranges than expected nanopore ranges are reasonable when considering intermolecular interactions in addition to CO2–carbon pore interactions. Therefore, cooperative adsorption among CO2 in relatively narrow nanopores can allow for high density and high capacity adsorption.

scholarly journals Micellization of Pluronic P123 in Water/Ethanol/Turpentine Oil Mixed Solvents: Hybrid Particle–Field Molecular Dynamic Simulation

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1806
Author(s):  
Zhao ◽  
Ma ◽  
Li ◽  
De Nicola ◽  
Yu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Mixed Solvent ◽  
Mixed Solvents ◽  
Simulation Method ◽  
The Self ◽  
Dynamics Simulation ◽  
Radius Of Gyration ◽  
Particle Field ◽  
Hybrid Particle ◽  
Pluronic P123

The hybrid particle–field molecular dynamics simulation method (MD-SCF) was applied to study the self-assembly of Pluronic PEO20-PPO70-PEO20 (P123) in water/ethanol/turpentine oil- mixed solvents. In particular, the micellization process of P123 at low concentration (less than 20%) in water/ethanol/turpentine oil-mixed solvents was investigated. The aggregation number, radius of gyration, and radial density profiles were calculated and compared with experimental data to characterize the structures of the micelles self-assembled from P123 in the mixed solvent. This study confirms that the larger-sized micelles are formed in the presence of ethanol, in addition to the turpentine oil-swollen micelles. Furthermore, the spherical micelles and vesicles were both observed in the self-assembly of P123 in the water/ethanol/turpentine oil-mixed solvent. The results of this work aid the understanding of the influence of ethanol and oil on P123 micellization, which will help with the design of effective copolymer-based formulations.

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