Diffusion through ordered force fields in nanopores represented by Smoluchowski equation
- University of Queensland, Brisbane, Qld. (Australia). School of Engineering
The classical Einstein or Fick diffusion equation was developed in random force fields. When the equation is applied to gas transport through coal, significant discrepancies are observed between experimental and simulation results. The explanation may be that the random force field assumption is violated. In this article, we analyze molecular transport driven by both random and ordered (directional) forces in nanopores. When applied to CO{sub 2} transport through cone-shaped carbon nano-tubes (CNTs) and Li{sup +} doped graphite pores, computational results show that directional force fields may significantly affect porous media flow. Directional forces may be generated by potential gradients arising from a range of non-uniform characteristics, such as variations in the pore-sizes and in local surface compositions. On the basis of the simulation and experimental results, the Smoluchowski and Fokker-Planck equations, which account for the directional force fields, are recommended for diffusion through ordered force fields in nanopores.
- OSTI ID:
- 21212638
- Journal Information:
- AIChE Journal, Vol. 55, Issue 6; ISSN 0001-1541
- Country of Publication:
- United States
- Language:
- English
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