Critical Properties of Lennard-Jones Fluids in Narrow Slit-Shaped Pores

Vishnyakov, Aleksey; Piotrovskaya, E. M.; Brodskaya, E. N.; Votyakov, E. V.; Tovbin, Yu. K.

doi:10.1021/la001641a

Cited by 103 publications

(75 citation statements)

References 41 publications

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“…The LGM provides good agreement with mo lecular dynamic calculations of the self diffusion coeffi cient for one component fluids, while requiring less time. 16,17 For narrow pore systems, the model also pro vides phase diagrams of one component fluids, which are in good agreement with the diagrams 18, 19 and viscosity coefficients of one component fluids 20, 21 obtained by Monte Carlo and molecular dynamics methods.…”

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confidence: 64%

Self-diffusion, mass transfer, and viscosity coefficients for a binary mixture in narrow slit-like pores

Tovbin

Rabinovich

2005

Russ Chem Bull

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The concentration dependences of the dynamic characteristics of a binary mixture in narrow slit shaped pores of different widths are considered. The local and mean partial self diffusion, label transfer, mass transfer (mutual diffusion), and shear viscosity coefficients for binary mixtures of various compositions were calculated. The calculation was based on the lattice gas model in the quasichemical approximation for spherical components with approxi mately the same size. The calculation of dynamic characteristics took into account collisions between the molecules that determine the direction of their motion. All the kinetic coefficients depend substantially on the mixture density, the direction of motion, and the distance to the pore wall. The effect of the pore width on the calculated dynamic characteristics is considered.

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confidence: 64%

Self-diffusion, mass transfer, and viscosity coefficients for a binary mixture in narrow slit-like pores

Tovbin

Rabinovich

2005

Russ Chem Bull

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“…component, narrow-pore fluids with the use of the indicated model agree well with the diagrams obtained in [18,19] when the viscosity coefficients of these fluids [20] are determined by the Monte Carlo method and the method of molecular dynamics. To calculate the shear viscosity of a mixture in a pore, it is necessary to know the equilibrium local distributions of mixture components in the cross section of the pore, which depends substantially on the adsorbent-adsorbate interaction potential and the width of the pore.…”

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confidence: 61%

Viscosity of a binary fluid in narrow slot-like pores

Tovbin

Gvozdeva

Zhidkova

2006

J Eng Phys Thermophys

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533.7 + 541.183 The concentration dependences of the shear-viscosity coefficient of a fluid, representing a binary mixture of components with molecules of approximately equal sizes, in narrow slot-like pores filled to a different degree (from a rarefied gas to a liquid) have been theoretically investigated with the use of a lattice-gas model accounting for the characteristic volume of atoms and interactions between them in the quasichemical approximation. This model allows one to determine the self-consistent equilibrium characteristics of a vapor-liquid system and the shear-viscosity coefficients of molecules with the use of a unique set of energy parameters. The influence of the activation energy of the surface migration of molecules on the local coefficients of viscosity has been considered. A molecular interpretation of the sliding friction of a fluid near the walls of pores has been given; this effect was explained by the surface migration of the mixture components.The transport of molecules in porous bodies determines the dynamic characteristics of gas and liquid flows in them. The sizes of the pores of disperse materials determine the catalytic, adsorption, and membrane processes occurring in them as well as the processes of their cleaning, wetting, impregnation, and drying [1-6]. The maximum width of narrow pores is equal to ,10 nm for a short-range, nonspecific, Lennard-Jones interaction potential between molecules (6-12), which corresponds to 25-30 monolayers [7][8][9]. This value was obtained from analysis of the conditions under which the surface potential influences the capillary condensation (for a long-range interaction potential, it increases with increase in the radius of the potential).In a narrow pore, the surface potential significantly influences the mobility of molecules and their distribution over the cross section of the pore. All transport characteristics of an adsorbate in such pores differ from those in the bulk of vapor and liquid phases. Among the most important dynamic characteristics of a substance is its shear viscosity. It should be noted that the Navier-Stokes equation cannot be used for narrow pores. In this case, kinetic transport equations for condensed media should be used. For organization and simulation of flows in narrow pores, it is necessary to know the transport characteristics of the system of these pores at the molecular level. In [10,11], a new molecular approach to representation of flows in narrow pores of one-component fluids with densities and temperatures varying in wide ranges has been proposed. It is based on the simplest molecular model of condensed media -the lattice-gas model that accounts for the characteristic volume of molecules and their interaction with each other [12,13]. This model can be used for fluids with concentrations changing in a wide range (from the gaseous to the liquid state) at widely varying temperatures, including the critical one, which allows one to investigate the dynamics of a fluid flow in the case of capillary condensation. Cl...

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“…The critical property data, obtained in this work, are available electronically ͑EPAPS͒. 59 It was noted by earlier investigators 13,14,26 that ⌬T cr is inversely proportional to the pore size. Those studies, however, were limited to the pore size of few molecular diameters.…”

Section: A Phase Diagram Under Confinementmentioning

confidence: 87%

“…Numerous theoretical studies and molecular simulations including density function theory [15][16][17][18] and Monte Carlo ͑MC͒ simulations [19][20][21][22][23][24][25] were performed to understand capillary condensation. Vishnyakov et al 26 were the first to perform MC simulations systematically on carbon slit pores and studied the shift of the vapor-liquid critical point under confinement. Interestingly, they obtained similar results as seen experimentally; however, the simulations were limited to five molecular diameters pore size.…”

Section: Introductionmentioning

confidence: 99%

Vapor-liquid critical and interfacial properties of square-well fluids in slit pores

Jana

Singh

Kwak

2009

The Journal of Chemical Physics

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Computer simulation studies of a square-well fluid in a slit pore. Spreading pressure and vapor-liquid phase equilibria using the virtual-parameter-variation method J. Chem. Phys. 112, 5168 (2000) Vapor-liquid phase equilibria of square-well ͑SW͒ fluids of variable interaction range: = 1.25, 1.75, 2.0, and 3.0 in hard slit pores are studied by means of grand-canonical transition-matrix Monte Carlo ͑GC-TMMC͒ simulation. Critical density under confinement shows an oscillatory behavior as slit width, H, reduced from 12 to 1 . Two linear regimes are found for the shift in the critical temperature with the inverse in the slit width. The first regime is seen for H Ͼ 2.0 with linear increase in the slope of shift in the critical temperature against inverse slit width with increasing interaction range. Subsequent decrease in H has little consequence on the critical temperature and it remains almost constant. Vapor-liquid surface tensions of SW fluids of variable well extent in a planar slit pore of variable slit width are also reported. GC-TMMC results are compared with that from slab based canonical Monte Carlo and molecular dynamics techniques and found to be in good agreement. Although, vapor-liquid surface tension under confinement is found to be lower than the bulk surface tension, the behavior of surface tension as a function of temperature is invariant with the variable pore size. Interfacial width, , calculated using a hyperbolic function increases with decreasing slit width at a given temperature, which is contrary to what is being observed recently for cylindrical pores. Inverse scaled interfacial width ͑ / H͒, however, linearly increases with increase in the scaled temperature ͑T c,bulk − T͒ / T c,bulk .

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Critical Properties of Lennard-Jones Fluids in Narrow Slit-Shaped Pores

Cited by 103 publications

References 41 publications

Self-diffusion, mass transfer, and viscosity coefficients for a binary mixture in narrow slit-like pores

Self-diffusion, mass transfer, and viscosity coefficients for a binary mixture in narrow slit-like pores

Viscosity of a binary fluid in narrow slot-like pores

Vapor-liquid critical and interfacial properties of square-well fluids in slit pores

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