Equation-of-state modeling of associating-fluids phase equilibria in nanopores

Tan, Sugata P.; Piri, Mohammad

doi:10.1016/j.fluid.2015.07.044

Cited by 44 publications

(42 citation statements)

References 31 publications

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“…Recently, another thermodynamic EOS based on the perturbed-chain statistical associating fluid theory, namely, the PC-SAFT EOS coupled with the modified Laplace equation, has been developed to calculate the phase equilibria of both pure components and mixtures in confined spaces. , With parameters derived from confined pure components, it can predict the phase behavior of the binary mixtures of those components in the same nanopores, which shows great consistency with the available experimental data. Subsequently, the authors drew a new and interesting conclusion that the dew-point and bubble-point curves of confined mixtures ended at some moderate pressures and temperatures .…”

Section: Introductionmentioning

confidence: 84%

Experimental Study on the Criticality of a Methane/Ethane Mixture Confined in Nanoporous Media

et al. 2019

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For the first time, the critical region of a methane/ethane mixture confined in nanoporous media (SBA-15) is experimentally investigated using differential scanning calorimetry with an isochoric cooling procedure. The results reveal that the supercritical region of the confined fluid mixture exists at a lower pressure than its counterpart in the bulk space. The shift of the critical region is dependent on the pore size, which is similar to that of pure fluids [Tan et al., J. Phys. Chem. C, 2019, 123, 9824–9830]. Specifically, compared to that in bulk, the shift is greater for smaller pore size. The heat of capillary condensation of this mixture is also discussed. The findings in this work would shed some light on the understanding of confined phase behavior, especially criticality, in investigations toward more complex confined mixtures encountered in practical engineering application, for example, oil and gas recovery from unconventional reservoirs.

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Section: Introductionmentioning

confidence: 84%

Experimental Study on the Criticality of a Methane/Ethane Mixture Confined in Nanoporous Media

et al. 2019

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“…Equilibrium liquid and vapor densities were calculated using the PC-SAFT equation of state (EOS) . The EOS parameters for propane were taken from Gross and Sadowski, and those for n -pentane and n -hexane were obtained from Tan and Piri . The binary interaction parameter k ij is obtained from fitting over the vapor–liquid equilibria data of the mixture to correct the interaction energy between unlike molecules when necessary.…”

Section: Methodsmentioning

confidence: 99%

Effects of Temperature and Pressure on Interfacial Tensions of Fluid Mixtures. II. Propane/n-Pentane and Propane/n-Hexane Binaries

et al. 2021

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We use the experimental setup and protocols described in Toutouni et al. (Effects of Temperature and Pressure on Interfacial Tensions of Fluid Mixtures. I. CO2/n-Pentane Binary. J. Chem. Eng. Data, 2021, DOI 10.1021/acs.jced.0c01044) to examine the impacts of temperature and pressure on interfacial tensions (IFT) of binary hydrocarbon systems propane/n-pentane and propane/n-hexane. The pressure and temperature vary from 0.2 to 3.5 MPa and 323.15 to 403.15 K for the propane/n-pentane fluid system and from 0.18 to 3.5 MPa and 296.15 to 403.15 K for the propane/n-hexane fluid system. The results indicate that the IFT values of both fluid systems follow the same trends with changes in pressure and temperature. It is observed that when pressure increases isothermally, the IFT values decrease. Furthermore, when increasing temperature isobarically, the IFT values exhibit a decreasing trend at low pressures, but the trend reverses at higher pressures. The measured data also reveal that, at a given pressure and temperature, the IFT value of the propane/n-pentane system is lower than that of the propane/n-hexane system. The difference between the two IFT values decreases as pressure increases isothermally.

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“…In addition to our observations, other researchers also reported similar "water bridges" in the inorganic nanopore, 10,12,14,18 also known as capillary bridge or capillary condensation. 13,79,80 It is worth noting that the capillary condensation often occurs when two water films are adequately close to each other. 12 In this study, the water bridge still persists in P−H nanopores at even a 10 or 15 nm pore width, as shown in Figures 6 and 7.…”

Section: ■ Methodsmentioning

confidence: 99%

Water Bridges in Clay Nanopores: Mechanisms of Formation and Impact on Hydrocarbon Transport

2020

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Clays are prevalent in the earth's crust and usually deposited in the presence of water. An unusual finding in clays is that under certain conditions, water molecules can collectively form a bridge across a clay-hosted pore. However, there are relatively few studies focused on the formation mechanism of the water bridge in clay nanopores. In this work, we use molecular dynamics simulations to investigate the formation of the water bridge and its influence on fluid transport in slit-shaped illite nanopores. Two different basal illite surface chemistries are constructed: potassium− hydroxyl (P−H) and hydroxyl−hydroxyl (H−H) structures. Because pore size and water concentration are expected to control the formation of the water bridge, our simulations span a wide range of pore sizes and water concentrations. Generally, positive potassium layers and negative hydroxyl groups in P−H nanopore can induce partial charges which in return produce instant and local electric fields, favoring the formation of the water bridge. In P−H nanopores, the water bridge happens at a relatively low water concentration. However, in H−H nanopores, the water bridge only forms at high water concentrations. Additionally, smaller pore sizes favor the formation of water bridges. However, the presence of an electric field promotes the formation of a water bridge even in larger pore sizes in P−H pores. The results also indicate that in both P−H and H−H nanopores, water adsorption films initially create a smooth surface to promote the hydrocarbon flow. In P−H nanopores, further increases in the water concentration causes a sharp decline in the self-diffusion coefficients of the hydrocarbon and water due to the formation of the water bridge. The presence of electric fields in P−H pores can however weaken the confinement effect of illite and promote the hydrocarbon flow. In contrast, in H−H nanopores, the self-diffusion coefficients decline slowly with the increase of water concentration. This is because no water bridge is formed at low water concentrations in H−H nanopores.

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Equation-of-state modeling of associating-fluids phase equilibria in nanopores

Cited by 44 publications

References 31 publications

Experimental Study on the Criticality of a Methane/Ethane Mixture Confined in Nanoporous Media

Experimental Study on the Criticality of a Methane/Ethane Mixture Confined in Nanoporous Media

Effects of Temperature and Pressure on Interfacial Tensions of Fluid Mixtures. II. Propane/n-Pentane and Propane/n-Hexane Binaries

Water Bridges in Clay Nanopores: Mechanisms of Formation and Impact on Hydrocarbon Transport

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