A Novel Porous Diffusion Model during Gas Desorption in Coal Based on Fractal Characteristics of Pore Structure
Publication: Journal of Energy Engineering
Volume 150, Issue 3
Abstract
In order to clarify the relationship between the conventional diffusion models and the time-dependent diffusion model during gas desorption, a porous diffusion model during gas desorption in coal was established by modeling the pore structure according to the porous diffusion theory and fractal theory. Gas diffusion processes were experimentally measured using a series of coal samples with different ranks and types under different gas equilibrium pressures. And the established theoretical model was furthermore verified by experimental data. The theoretical data derived from the established porous diffusion model agreed well with the experimental data with correlation coefficients greater than 99.0%. The attenuation of diffusion coefficient during gas desorption was essentially attributed to the gradual decrease of the gas diffusion amount for large pores during unsteady diffusion of gas in porous media. The effective diffusion coefficient presented a first fast and then slow decreasing trend with the prolonged diffusion time. The diffusion coefficient increased with the increase of gas equilibrium pressure as well as the metamorphic grade and fragmentation degree of coal. The pore connectivity enhanced as the surface area proportion of larger pores increased, leading to an increase in the proportion of the gas diffusion quantity in larger pores and the diffusion coefficient and meanwhile a decrease in the fractal dimension. This study will provide theoretical support for in-depth understanding of the gas diffusion mechanism in gas-containing coal.
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Data Availability Statement
All data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The study was funded by the Natural Science Research of Jiangsu Higher Education Institutions of China (22KJB620002 and 23KJD530001) and Open Foundation of Key Laboratory of Safety and High-efficiency Coal Mining, Ministry of Education (Anhui University of Science and Technology) (No. JYBSYS2020210).
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Information & Authors
Information
Published In
Journal of Energy Engineering
Volume 150 • Issue 3 • June 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Sep 22, 2023
Accepted: Jan 19, 2024
Published online: Mar 28, 2024
Published in print: Jun 1, 2024
Discussion open until: Aug 28, 2024
ASCE Technical Topics:
- Chemical processes
- Chemistry
- Coal
- Desorption
- Diffusion
- Diffusion (porous media)
- Energy engineering
- Energy sources (by type)
- Engineering fundamentals
- Engineering materials (by type)
- Engineering mechanics
- Environmental engineering
- Fractals
- Fuels
- Geometry
- Materials engineering
- Mathematics
- Models (by type)
- Non-renewable energy
- Porous media
- Structural models
- Thermodynamics
- Transport phenomena
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