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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

The Mean Free Path of Gas Molecules in Confined Nano-porous Structures

Get access (open in a dialog) DOI: 10.1615/IHTC15.cnd.008813
pages 1577-1585

Résumé

Based on the Zeng’s model and in combination with simplified unit cell structure of cubic array of nano-spheres, the influencing factors, mechanism, and variation process of mean free path in confined nano-porous structures are analyzed in this paper. The results show that the nano-porous structure features of nano-porous materials are directly related with specific surface area and density. The mean free path of molecules in confined nanoporous structures decreases apparently with the rising of specific surface area and density. The nano-porous materials with a relative higher specific surface area and a larger density are more favorable for confining the gaseous conductivity in nano pores. It is shown that p=104 Pa and p=4×105 Pa are two inflection pressures at ambient temperatures. When p<104 Pa, the mean free path of molecules almost does not change with vary of pressure due to the restriction effect of nano-porous structures. When p>4×105 Pa, the limiting effect of nanoporous structures on movement of molecules can be ignored, the mean free path of gas molecules in nanoporous materials approach to the mean free path of gas molecules in free space. With the increase of temperature, the mean free path of gas molecules in nano-porous space is increasing, while, the increasing rate decreases gradually.