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Journal ArticleDOI

Effect of the fluid-wall interaction on freezing of confined fluids: Toward the development of a global phase diagram

14 Jun 2000-Journal of Chemical Physics (American Institute of PhysicsAIP)-Vol. 112, Iss: 24, pp 11048-11057
TL;DR: In this article, the effect of the fluid-wall interaction energy on the shift of the freezing temperature and on the fluid structure is considered, using a novel approach to calculate the free energy surface based on Landau theory and order parameter formulation.
Abstract: We report molecular simulation studies of the freezing behavior of fluids in nano-porous media. The effect of confinement is to induce spatial constraints as well as energetic heterogeneity on the confined fluid, thereby altering the bulk phase behavior drastically. We consider the effect of the fluid-wall interaction energy on the shift of the freezing temperature and on the fluid structure, using a novel approach to calculate the free energy surface based on Landau theory and order parameter formulation. Corresponding states theory is then used to map out the global freezing behavior of a Lennard-Jones (LJ) fluid in model slit-shaped pores of varying fluid-wall interaction strengths. Using LJ parameters fitted to thermophysical property behavior, we predict the qualitative freezing behavior for a variety of fluids and nano-porous materials, based on a global freezing diagram. We have attempted to verify these predictions by comparing with experimental data for several systems, and show that in these cases, the experimental observations and the predictions are in agreement.

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Citations
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Journal ArticleDOI
TL;DR: In this paper, a water-like model confined between two fixed hydrophobic plates is studied using molecular dynamic simulations, and the system is tested for density, diffusion and structural anomalous behavior and compared with the bulk results.
Abstract: Using molecular dynamic simulations we study a waterlike model confined between two fixed hydrophobic plates. The system is tested for density, diffusion and structural anomalous behavior and compared with the bulk results. Within the range of confining distances we had explored we observe that in the pressure-temperature phase diagram the temperature of maximum density (TMD line), the temperature of maximum and minimum diffusion occur at lower temperatures when compared with the bulk values. For distances between the two layers below a certain threshold ,$d\le d_c$, only two layers of particles are formed, for $d\ge d_c$ three or more layers are formed. In the case of three layers the central layer stays liquid while the contact layers crystallize. This result is in agreement with simulations for atomistic models.

44 citations

Journal ArticleDOI
TL;DR: In this article, all-atom molecular dynamics simulations of water confined in graphite and mica slit pores of variable size ranging from 10 to 60 A. For each pore size, the authors demonstrate that the confinement...
Abstract: We report all-atom molecular dynamics simulations of water confined in graphite and mica slit pores of variable size ranging from 10 to 60 A. For each pore size, we demonstrate that the confinement...

41 citations

Journal ArticleDOI
TL;DR: The results of coupled reactive-transport processes common to most geological environments depend on the properties and reactivity of these crustal fluids over broad ranges of temperature, pressure and fluid composition as discussed by the authors.
Abstract: Throughout Earth’s crust and upper mantle, fluids play the dominant role in transporting and concentrating Earth’s energy and mineral resources (Liebscher and Heinrich 2007). Furthermore, the flux of fluids, which act as both reaction media and reactants, strongly influences the genesis and evolution of many different kinds of rocks. Among many different types of fluids, those containing volatile carbon, hydrogen and oxygen (C-H-O) species tend to dominate in the lithosphere along with various electrolytes and silica. These fluids commonly contain methane as both a major constituent and an important energy source. Conventional natural gas deposits reside in sedimentary basins where fluid overpressure often results in brittle failure of the confining rocks. Industry exploration and exploitation of shale gas (e.g., the Marcellus, Utica, and Barnett formations) has refocused attention on understanding the fundamental behavior of volatile hydrocarbon—rock interactions. Recent observations of hydrocarbons emanating from non-sedimentary systems (abiogenic), such as mid-ocean ridge hydrothermal systems or occurring within some crystalline rock-dominated Precambrian shield environments have challenged the view that organic rich sediments provide the only significant source of crustal hydrocarbons (Potter and Konnerup-Madsen 2003; Sleep et al. 2004; Sherwood Lollar et al. 2006; McCollom 2013; Sephton and Hazen 2013). Geopressured-geothermal regimes contain C-H-O fluids with vast energy potential in the form of methane and hot water at high pressure. Even fluid inclusions from both metamorphic and igneous terrains record the presence of methane-bearing fluids reflecting reduced redox state conditions of formation. The consequences of coupled reactive-transport processes common to most geological environments depend on the properties and reactivity of these crustal fluids over broad ranges of temperature, pressure and fluid composition. The relative strengths of complex molecular-scale interactions in geologic fluids, and the changes in those interactions with temperature, pressure, and fluid composition, are the fundamental basis for observed …

39 citations


Cites background from "Effect of the fluid-wall interactio..."

  • ...Sometimes exotic phases, not observable for bulk systems, can be observed under confinement (e.g., the hexatic phase) (Radhakrishnan et al. 2000, 2002)....

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Journal ArticleDOI
TL;DR: A simple model to describe the triple point is developed and shown to agree well with the results of the simulation, and the importance of the two factors in nanoscale pores, which cannot be described by the classic Gibbs-Thomson equation, is emphasized.
Abstract: We report the results of a molecular dynamics simulation that looked for the triple point of Lennard-Jones fluid in slit-shaped nanopores. The simulation method employed for this purpose is able to maintain vapor–liquid coexistence in a nanopore at a specific equilibrium bulk-phase pressure. The triple point is the freezing point of the critical condensate. The triple-point temperature could be higher or lower than the bulk triple point, depending on the pore size. This is thought to be due to two opposing factors: the elevating effect of the pore-wall potential energy, and the depressing effect of the capillary condensate’s tensile condition. Because of the cancellation, the deviation of the triple-point temperature from the bulk triple-point temperature was not considered significant. The pressure of the triple point, however, was significantly different from that of the bulk triple point. A simple model to describe the triple point is developed and shown to agree well with the results of the simulation. The importance of the two factors in nanoscale pores, which cannot be described by the classic Gibbs–Thomson equation, is emphasized.

38 citations

Journal ArticleDOI
TL;DR: In this paper, a qualitative comparison between experimental measurements and molecular simulations of the freezing and melting of azeotropic mixtures confined in nanoporous materials was made, and the structure of the crystal phase in the simulations was investigated by means of positional and bond-orientational pair correlation functions and appropriate bond-order parameters.
Abstract: The paper reports on a qualitative comparison between experimental measurements and molecular simulations of the freezing and melting of azeotropic mixtures confined in nanoporous materials. Dielectric relaxation spectroscopy was used to determine the experimental solid/liquid phase diagram of CCl4/C6H12 mixtures confined in activated carbon fibres. Grand Canonical Monte Carlo simulations combined with the parallel tempering technique were used to model the freezing of the azeotropic Lennard–Jones mixture Ar/CH4 in a graphite slit pore. The structure of the crystal phase in the simulations is investigated by means of positional and bond-orientational pair correlation functions and appropriate bond-order parameters. Both simulations and experiments show that the phase diagram of the confined mixture is of the same type as that for the bulk, but the solid/liquid coexistence lines are located at higher temperatures. The effect of confinement and of the wall/fluid interaction on the location of the azeotrope ...

38 citations

References
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Book
01 Jan 1954
TL;DR: Molecular theory of gases and liquids as mentioned in this paper, molecular theory of gas and liquids, Molecular theory of liquid and gas, molecular theories of gases, and liquid theory of liquids, مرکز
Abstract: Molecular theory of gases and liquids , Molecular theory of gases and liquids , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

11,807 citations

Book
01 Jan 1995
TL;DR: In this article, the authors present a generalization of the renormalization group of mean field theories, critical phenomena, and topological defects, including walls, kinks and solitons.
Abstract: Preface 1. Overview 2. Structure and scattering 3. Thermodynamics and statistical mechanics 4. Mean-field theory 5. Field theories, critical phenomena, and the renormalization group 6. Generalized elasticity 7. Dynamics: correlation and response 8. Hydrodynamics 9. Topological defects 10. Walls, kinks and solitons Glossary Index.

3,223 citations

Journal ArticleDOI
TL;DR: In this paper, the potential energy of a gas atom interacting with a solid having a surface made up of single type of exposed lattice plane can be expressed as a Fourier series in the position variables in the plane parallel to the surface.

1,379 citations

Journal ArticleDOI
TL;DR: In this paper, the free energy of a Lennard-Jones fluid in the liquid-vapour coexistence region was estimated by relating it to that of the inverse-twelve (soft sphere) fluid, which itself shows no condensation.

1,179 citations