Elasticity and phase behaviour of n-heptane and n-nonane in nanopores

Schappert, Klaus; Gemmel, Laura; Meisberger, Dennis; Pelster, R.

doi:10.1209/0295-5075/111/56003

Cited by 13 publications

(15 citation statements)

References 32 publications

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“…At the same time, this is consistent with the classical surface force measurements for the fluids confined between two parallel planes: when the gap between the planes is on the order of a nanometer, such measurements show that the fluid has the shear viscosity exceeding the bulk value by seven orders of magnitude [146]. Such dramatic increase of the shear forces, could have an effect on the shear modulus measured in ultrasonic experiments at frequencies of 7 MHz [141].…”

Section: Relation Between the Ultrasonic Measurements And Adsorption-induced Deformationsupporting

confidence: 87%

“…Figure 20 shows one of the results from their work: the shear modulus of the solid sample saturated with heptane exceeds the shear modulus of the dry sample even at temperatures above the confined melting point. Similar observations were made for nonane [141]. It suggests that liquid heptane and nonane, when confined in the pores of Vycor glass, have non-zero shear moduli.…”

Section: Relation Between the Ultrasonic Measurements And Adsorption-...supporting

confidence: 77%

“…This phenomena is seen clearly in speed of wave propagation measurements. This signature of phase transitions has been used in a number of works to monitor the freezing of fluids in confinement, such as helium [136,137], argon [94,102,113,114,138], nitrogen [139], oxygen [140], mercury [98,99], and alkanes [101,141]. However, many of these works did not quantify the elastic properties of confined phases.…”

Section: Relation Between the Ultrasonic Measurements And Adsorption-...mentioning

confidence: 99%

“…Schappert et al used transverse waves to probe confined fluids which have more complex structure, nheptane, and n-nonane [141]. Figure 20 shows one of the results from their work: the shear modulus of the solid sample saturated with heptane exceeds the shear modulus of the dry sample even at temperatures above the confined melting point.…”

Section: Relation Between the Ultrasonic Measurements And Adsorption-...mentioning

confidence: 99%

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Elastic properties of confined fluids from molecular modeling to ultrasonic experiments on porous solids

Dobrzanski

Gurevich

Gor

2021

Applied Physics Reviews

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Fluids confined in nanopores are ubiquitous in nature and technology. In recent years, the interest in confined fluids has grown, driven by research on unconventional hydrocarbon resources -shale gas and shale oil, much of which are confined in nanopores. When fluids are confined in nanopores, many of their properties differ from those of the same fluid in the bulk. These properties include density, freezing point, transport coefficients, thermal expansion coefficient, and elastic properties. The elastic moduli of a fluid confined in the pores contribute to the overall elasticity of the fluid-saturated porous medium and determine the speed at which elastic waves traverse through the medium. Wave propagation in fluid-saturated porous media is pivotal for geophysics, as elastic waves are used for characterization of formations and rock samples. In this paper, we present a comprehensive review of experimental works on wave propagation in fluid-saturated nanoporous media, as well as theoretical works focused on calculation of compressibility of fluids in confinement. We discuss models that bridge the gap between experiments and theory, revealing a number of open questions that are both fundamental and applied in nature. While some results were demonstrated both experimentally and theoretically (e.g. the pressure dependence of compressibility of fluids), others were theoretically predicted, but not verified in experiments (e.g. linear scaling of modulus with the pore size). Therefore, there is a demand for the combined experimental-modeling studies on porous samples with various characteristic pore sizes. The extension of molecular simulation studies from simple model fluids to the more complex molecular fluids is another open area of practical interest.

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Section: Relation Between the Ultrasonic Measurements And Adsorption-induced Deformationsupporting

confidence: 87%

Section: Relation Between the Ultrasonic Measurements And Adsorption-...supporting

confidence: 77%

Section: Relation Between the Ultrasonic Measurements And Adsorption-...mentioning

confidence: 99%

Section: Relation Between the Ultrasonic Measurements And Adsorption-...mentioning

confidence: 99%

See 2 more Smart Citations

Elastic properties of confined fluids from molecular modeling to ultrasonic experiments on porous solids

Dobrzanski

Gurevich

Gor

2021

Applied Physics Reviews

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“…Figure (left) shows the structure of Vycor based on a combination of experimental characterization techniques (Levitz et al, ). Vycor has high porosity and narrow pore size distribution; these features made it widely used as a medium for studying confinement effects for various solid and fluid phases (Egorov et al, ; Filippov et al, ; Gruener et al, ; Soprunyuk et al, ; Schappert et al, , ; Uskov et al, ). Note also that combination of various experimental methods used to calculate the porosity of Vycor suggests that Vycor does not have isolated (occluded) porosity (Levitz et al, ; Page et al, ).…”

Section: Methodsmentioning

confidence: 99%

Gassmann Theory Applies to Nanoporous Media

Gor

Gurevich

2018

Geophysical Research Letters

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Recent progress in extraction of unconventional hydrocarbon resources has ignited the interest in the studies of nanoporous media. Since many thermodynamic and mechanical properties of nanoscale solids and fluids differ from the analogous bulk materials, it is not obvious whether wave propagation in nanoporous media can be described using the same framework as in macroporous media. Here we test the validity of Gassmann equation using two published sets of ultrasonic measurements for a model nanoporous medium, Vycor glass, saturated with two different fluids, argon, and n‐hexane. Predictions of the Gassmann theory depend on the bulk and shear moduli of the dry samples, which are known from ultrasonic measurements and the bulk moduli of the solid and fluid constituents. The solid bulk modulus can be estimated from adsorption‐induced deformation or from elastic effective medium theory. The fluid modulus can be calculated according to the Tait‐Murnaghan equation at the solvation pressure in the pore. Substitution of these parameters into the Gassmann equation provides predictions consistent with measured data. Our findings set up a theoretical framework for investigation of fluid‐saturated nanoporous media using ultrasonic elastic wave propagation.

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Density Functional Study on Enhancement of Modulus of Confined Fluid in Nanopores

Sun

Kang

2019

Ind. Eng. Chem. Res.

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Elastic modulus in fluid is a crucial thermodynamic property due to its close relation to the viscoelastic behaviors in dynamics and the pore size analysis in porous materials. Especially, elasticity in nanoconfined fluid, which exhibits significant deviation from that of bulk fluid, has gained a multitude of applications in industrial and engineering fields. In this work, general expressions of bulk and shear moduli for inhomogeneous fluids have been derived based on Hooke's law. In the bulk phase, the obtained moduli reduce exactly to those obtained from thermodynamic fluctuation theory. In addition, both moduli have been expressed as functionals of fluid density functions. Besides, the Cauchy relation and Voigt notation for inhomogeneous elasticity have been first obtained. The validity of the obtained moduli has been verified through their comparison with grand canonical Monte Carlo simulation. Our further calculations suggest that the bulk modulus of confined fluid is inhomogeneous across the pore and the averaged bulk modulus is significantly enhanced by the confinement. In addition, the pore size dependence of the bulk modulus and the related Tait−Murnaghan equation have also been investigated in confined argon. It is found that in small pores, the modulus and Tait−Murnaghan equation show obvious oscillation with pore size. For larger pores, however, these properties reduce linearly to the values in the bulk case.

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Elasticity and phase behaviour of n-heptane and n-nonane in nanopores

Cited by 13 publications

References 32 publications

Elastic properties of confined fluids from molecular modeling to ultrasonic experiments on porous solids

Elastic properties of confined fluids from molecular modeling to ultrasonic experiments on porous solids

Gassmann Theory Applies to Nanoporous Media

Density Functional Study on Enhancement of Modulus of Confined Fluid in Nanopores

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