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Influence of confinement on thermodiffusion.
Rachid Hannaoui1, Guillaume Galliero, Hai Hoang
1LFC-R (UMR5150 with CNRS and TOTAL), Université de Pau et des Pays de l'Adour, BP 1155, F-64013 Pau Cedex, France.
The Journal of Chemical Physics
|September 28, 2013
Summary
Confinement in nanoporous media has a negligible effect on the thermal diffusion factor of fluid mixtures. However, pore characteristics significantly influence mass diffusion and thermodiffusion coefficients, especially under strong adsorption and narrow pore widths.
Area of Science:
- Thermodynamics
- Fluid Dynamics
- Materials Science
Background:
- Understanding thermodiffusion in confined systems is crucial for various applications.
- Nanoporous materials offer unique environments for studying fluid behavior.
Purpose of the Study:
- To investigate the influence of nanoporous media on the thermodiffusion of fluid isotopic mixtures.
- To analyze the effects of pore characteristics on mass diffusion and thermodiffusion coefficients.
Main Methods:
- Molecular dynamics simulations of confined Lennard-Jones binary equimolar mixtures.
- Utilized grand-canonical like and non-equilibrium simulation approaches.
- Studied atomistic slit pores with varying widths and adsorbent natures under sub- and super-critical conditions.
Main Results:
- Confinement showed a negligible effect on the thermal diffusion factor (Soret coefficient) across all conditions.
- Mass diffusion and thermodiffusion coefficients were significantly influenced by pore characteristics.
- These coefficients decreased with stronger adsorption and smaller pore widths.
Conclusions:
- While the overall thermal diffusion factor is robust to confinement, individual transport coefficients are sensitive to nanopore environments.
- Hydrodynamic explanations support the observed decrease in diffusion coefficients with increased adsorption and reduced pore width.
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