doi:10.16186/j.cnki.1673-9787.2023010023

Received:2023/01/13

Revised:2023/03/02

Published:2024/03/25

Gas flow characteristics in micro and nano pores and its LBM numerical simulation

WANG Dengke1，2，3，YUAN Mingyu1，2，LI Zhen4，ZHANG Qingqing5，SHANG Zhengjie6，FU Jianhua6，WANG Yuexu6，TANG Jiahao1，2，GUO Yujie1，2，PANG Xiaofei1，2

1.State Key Laboratory Cultivation Base for Gas Geology and Gas Control，Henan Polytechnic University，Jiaozuo，454000，Henan，China；2.Collgeg of Safety Science and Engineering，Henan Polytechnic University，Jiaozuo，454000，Henan，China；3.Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization，Jiaozuo 454000，Henan，China；4.College of Safety and Emergency Management Engineering，Taiyuan University of Technology，Taiyuan 030024，Shanxi，China；5.China Coal Technology and Engineering Group Shenyang Research Institute Co.，Ltd.，Fushun 113122，Liaoning，China；6.Zhengzhou Coal Industry（Group）Co.，Ltd.，Zhengzhou 450000，Henan，China

Abstract: Objectives It is important to study the flow characteristics of gas in coal seams to reveal the mechanism of coal seam gas storage and transport characteristics.The number and structure of micro and nanoscale pores in coal are very complex，and to study the flow characteristics of coal seam gas in micro and nanoscale pores， Methods homogeneous nanoporous carbon films were tested and their pore size and porosity were qualitatively，and quantitatively analyzed by scanning electron microscopy experiments；the experimental study of gas flow in micro and nano pores was carried out by using a nano-scale gas flow characterization experimental device. Results A more accurate characterization of the flow of gases within micro- and nano-pores is obtained by comparing the conventional Darcy percolation model with a model applicable to gas flow at the micro-scale.The apparent permeability of nanoporous carbon films decreases with increasing inlet pressure in a negatively correlated linear law，while the gas permeability decreases with decreasing Knudsen number in a positively correlated linear law，indicating that the flow of gas at the micro- and nano-scale does not conform to the conventional Darcy’s law，and the slip effect and gas diffusion cannot be neglected.The lattice Boltzmann method is used to simulate the gas flow at different inlet pressures to obtain the outlet gas flow rate at different gas pressures.When compared with the experimental results，the average error of LBM simulation results is 8.25%，which is in good agreement with the test results，indicating that LBM numerical simulations effectively reveal the flow characteristics of gases at the micro- and nano-scale. Conclusions The results of the study can provide a reference for future research on gas flow mechanisms and flow patterns in coal seams.

Key words:micro-nanopores；nanoporous carbon；gas flow characteristics；LBM simulation；LBM-D2Q9 model