Computing Thermodynamic Properties of Fluids Augmented by Nanoconfinement: Application to Pressurized Methane

Area of Science:

• Thermodynamics and Statistical Mechanics
• Materials Science and Nanotechnology

Background:

• Nanoconfined fluids display unique thermodynamic properties distinct from bulk phases.
• Predicting thermodynamic quantities in nanoconfined systems is challenging due to confinement effects.
• Near-wall density profiles, driven by fluid-wall interactions and fluctuations, govern adsorption and capillary condensation.

Purpose of the Study:

• To develop a first-principles statistical mechanics framework for nanoconfined fluids.
• To model the influence of fluid-wall interactions on near-wall density amplification.
• To accurately predict thermodynamic behavior of compressible gases under confinement.

Main Methods:

• Developed a statistical mechanics framework incorporating fluid-wall interaction coupling.
• Applied the theory to compressible gases, specifically pressurized methane in confinement.
• Validated predictions against experimental data (small-angle neutron scattering) and atomistic simulations.

Main Results:

• The proposed theory accurately predicts adsorbed layer thickness.
• Density predictions under confinement show excellent agreement with experimental and simulation data for methane.
• The framework successfully describes the amplifying effect of fluid-wall interactions on near-wall density.

Conclusions:

• The developed statistical mechanics framework provides a rigorous, first-principles approach to nanoconfined fluids.
• The theory accurately captures key phenomena like near-wall density profiles and adsorbed layer thickness.
• The framework is generalizable for predicting phase transitions and nonequilibrium transport in nanoconfined systems.