Based on Zeng et al'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 nano-porous space 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 gas molecules in nano-porous space 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 space. It is shown that p=104 Pa and p=4×105 Pa are two inflection pressures. When p<104 Pa

the mean free path of gas molecules almost does not change with vary of pressure. When p>4×105 Pa

the limiting effect of nano-porous structures on movement of gas molecules can be ignored. With the increase of temperature

the mean free path of gas molecules in nano-porous space is increasing

while

the increasing rate decreases gradually.