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Gas sorption and transport in coals: a poroelastic medium approach.

Authors
Yi-J; Akkutlu-IY; Karacan-CO; Clarkson-CR
Source
Int J Coal Geol 2009 Jan; 77(1-2):137-144
NIOSHTIC No.
20034845
Abstract
In this paper, single-component gas sorption and transient diffusion processes are described within coal matrix exhibiting bimodal pore structure. The coal matrix is treated as a poroelastic medium manifesting swelling and shrinkage effects due to the sorption of gas under effective overburden stress. Gas transport is considered Fickian with molecular (bulk) and surface diffusion processes simultaneously taking place in the macro- and micropores of coal, respectively. The numerical formulation is intended to be explicit in nature to investigate the influences of sorption phenomena on the macropore volumes and on the overall gas transport for the cases of gas uptake by and release from coal. Results of the study show the presence of hysteresis during a sorption-desorption cycle of the gas. It is also found that the overall gas transport takes place at a rate significantly less than that in the macropores only. Thus the existence of a retardation effect in the overall gas transport is concluded. This retardation effect is primarily due to the micropore resistances, in particular gas adsorption, and is independent of the changes in the macropore volumes. It is shown that macroporosity of the coal matrix may change during gas transport due to combined effects of pressure and sorption-induced swelling or shrinkage of the coal. It is estimated that the macroporosity variation is non-uniform in space and time, as it is expected in reality, and typically taking values less than +/-10 percent of the initial porosity.
Keywords
Mining-industry; Coal-mining; Underground-mining; Gas-adsorption; Methanes; Author Keywords: Poroelastic medium; Bidisperse; Dual-sorption; Coal swelling; Sorption hysteresis
Contact
I.Y. Akkutlu, 100 East Boyd, Sarkeys Energy Center, Room T-311, Norman, OK 73079-1003, USA
CODEN
IJCGDE
Publication Date
20090107
Document Type
Journal Article
Email Address
akkutlu@ou.edu
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Issue of Publication
1-2
ISSN
0166-5162
NIOSH Division
PRL
Priority Area
Mining
Source Name
International Journal of Coal Geology
State
OK; PA
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