Direct visualization and molecular simulation of dewpoint pressure of a confined fluid in sub-10 nm slit pores

Yang, Qi; Jin, Bikai; Banerjee, Debjyoti; Nasrabadi, Hadi

doi:10.1016/j.fuel.2018.08.050

Cited by 49 publications

(23 citation statements)

References 33 publications

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“…The relative standard deviations of system pressure of the vapor phase at different temperatures were calculated for the last 10 000 cycles with a maximum of 4.2%, indicating that the equilibrium states were achieved, and the MC moves were sufficient to calculate the statistical averages of interested parameters. An MC simulation is usually conducted for 2–6 million MC steps, and the equilibrium results were averaged for the last one million steps, as proceeded in the literature …”

Section: Confinement Models and Simulation Detailsmentioning

confidence: 99%

“…An MC simulation is usually conducted for 2−6 million MC steps, and the equilibrium results were averaged for the last one million steps, as proceeded in the literature. 58 ■ RESULTS AND DISCUSSION Bulk Systems. The phase behaviors of hydrocarbons in the bulk environment have been adequately studied by experiments and the theoretical model of the Peng−Robinson equation of state (PR-EOS).…”

Section: ■ Introductionmentioning

confidence: 99%

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Confinement-Mediated Phase Behavior of Hydrocarbon Fluids: Insights from Monte Carlo Simulations

Rao

Xia

et al. 2020

Langmuir

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The phase behavior of hydrocarbon fluids confined in porous media has been reported to deviate significantly from that in the bulk environment due to the existence of sub-10 nm pores. Though experiments and simulations have measured the bubble/dew points and sorption isotherms of hydrocarbons confined in both natural and synthetic nanopores, the confinement effects in terms of the strength of fluid−pore interactions tuned by surface wettability and chemistry have received comparably less discussion. More importantly, the underlying physics of confinement-induced phenomena remain obfuscated. In this work, we studied the phase behavior and capillary condensation of n-hexane to understand the effects of confinement at the molecular level. To systematically investigate the pore effects, we constructed two types of wall confinements; one is a structureless virtual wall described by the Steele potential and the other one is an all-atom amorphous silica structure with surface modified by hydroxyl groups. Our numerical results demonstrated the importance of fluid−pore interaction, pore size, and pore morphology effects in mediating the pressure−volume−temperature (PVT) properties of hydrocarbons. The most remarkable finding of this work was that the saturation pressure predicted from the van der Waals-type adsorption isothermal loop could be elevated or suppressed relative to the bulk phase, as illustrated in the graphical abstract. As the surface energy (i.e., fluid−pore interaction) decreased, the isothermal vapor pressure increased, indicating a greater preference for the fluid to exist in the vapor state. Sufficient reduction of the fluid−pore interactions could even elevate the vapor pressure above that of the bulk fluid.

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Section: Confinement Models and Simulation Detailsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Confinement-Mediated Phase Behavior of Hydrocarbon Fluids: Insights from Monte Carlo Simulations

Rao

Xia

et al. 2020

Langmuir

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“…The smallest fluid technologies have much to offer the world’s large-scale fluid challengeenergy and associated CO 2 . Over the last 10 years microfluidic methods have matured in two key application areas of particular value to the energy sector: the measurement of physical properties , and the physical modelling of the pore-scale environment. − In the area of fluid property measurement, microfluidics has proven useful in determining mutual (e.g., CO 2 -oil) properties, such as diffusivities and solubilities, as well as testing emulsion system behaviors. − Although microfabricated physical models of the porous media (or micromodels) long predate microfluidics, − modern fabrication (e.g., silicon-glass microfluidics) and microscopy methods have greatly expanded these capabilities leading to a wide range of applied pressures (up to 50 MPa) and temperatures (up to 300 °C) and the study of pore sizes at unprecedented small scales (down to sub-10 nm). − …”

Section: Introductionmentioning

confidence: 99%

Accelerating Fluid Development on a Chip for Renewable Energy

et al. 2020

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From physical property measurement to modelling pore-scale environments, the study of fluids at the microscale is key to understanding and optimizing fluids for large-scale energy applications. Silicon-glass microfluidics is now a proven technology for chemical effectiveness testing in the conventional oil and gas energy sector. We see potential to apply microfluidic fluid characterization technology to renewable sectors, such as geothermal and solar thermal energy recovery where fluid customization is central to performance. Key to unlocking performance gains in these renewable energy systems are phase change material slurries (PCSs)fluids that exhibit a high apparent specific heat capacity. However, testing PCS synthesis recipes is currently a slow and expensive process, given the challenges of dynamic testing at process-relevant temperatures and pressures. In this work, we develop and test a robust silicon microfluidic device and measure important PCS emulsion properties including (i) viscosity, (ii) shear stability, (iii) phase change temperature/hysteresis, and (iv) phase change stability under dynamic conditions where tests are performed quickly (<1 h) and require only minimal test fluid volumes.

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“…Fisher and Israelachvili observed capillary condensation of cyclohexane between crossed mica cylinders at different radii ( r c ≥ 4 nm). Recently, direct observation , of propane and n -butane capillary condensation using nanofluidic devices was reported down to 8 nm pore sizes ( r c ≈ 4 nm). The observed deviations of the Kelvin equation are typically under 5%.…”

Section: Introductionmentioning

confidence: 99%

VT-Based Phase Envelope and Flash Calculations in the Presence of Capillary Pressure

Sandoval

Michelsen

Yan

et al. 2019

Ind. Eng. Chem. Res.

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Phase envelope construction and isothermal flash are two widely used phase equilibrium calculations. Because of the increasing importance of oil and gas production from shale, there is a need to perform these calculations in the presence of capillary pressure. Such calculations are also important for other processes inside porous media. Classical phase equilibrium calculations usually use P T-based thermodynamics that requires the solution of the equation of state (EoS) for the molar volume or density to calculate the desired thermodynamic properties. An alternative to this formulation is V T-based thermodynamics where repeated molar volume or density solutions are avoided by co-solving the equality of phase pressures in the equilibrium calculation. The formulation is particularly advantageous for equilibrium calculation with capillary pressure. It can naturally handle the negative pressures in the wetting phase (usually the liquid) caused by the capillary pressure. Furthermore, the capillary pressure function usually has a high level of implicitness for the pressure variable which can be circumvented in the V T-formulation. We present the V T-based formulations for 1 phase envelope construction and isothermal flash with capillary pressure. The incorporation of capillary pressure actually does not increase the number of equations since the pressure equality equation is included in the V T-based formulations without capillary pressure. Using volume as an independent variable result in simpler derivatives for the interfacial tension models, which is more suitable for cases with large capillary pressures or with saturation dependent capillary pressures that account for pore size distribution. The developed algorithms are tested for multicomponent reservoir fluid examples, including natural gas, gas condensate, and black oil, down to extremely small pore sizes. The algorithms converge with only a few Newton iterations even for the extreme cases. For the cases where pore size distribution is considered and the capillary pressure is treated as saturation dependent, the same convergence behavior is kept. This feature is especially attractive for reservoir simulation cases in which saturation dependent capillary pressure curves are used.

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Direct visualization and molecular simulation of dewpoint pressure of a confined fluid in sub-10 nm slit pores

Cited by 49 publications

References 33 publications

Confinement-Mediated Phase Behavior of Hydrocarbon Fluids: Insights from Monte Carlo Simulations

Confinement-Mediated Phase Behavior of Hydrocarbon Fluids: Insights from Monte Carlo Simulations

Accelerating Fluid Development on a Chip for Renewable Energy

VT-Based Phase Envelope and Flash Calculations in the Presence of Capillary Pressure

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Direct visualization and molecular simulation of dewpoint pressure of a confined fluid in sub-10 nm slit pores

Cited by 49 publications

References 33 publications

Confinement-Mediated Phase Behavior of Hydrocarbon Fluids: Insights from Monte Carlo Simulations

Confinement-Mediated Phase Behavior of Hydrocarbon Fluids: Insights from Monte Carlo Simulations

Accelerating Fluid Development on a Chip for Renewable Energy

VT-Based Phase Envelope and Flash Calculations in the Presence of Capillary Pressure

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Product

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Direct visualization and molecular simulation of dewpoint pressure of a confined fluid in sub-10 nm slit pores