Molecular dynamics simulation of oxygen diffusion in dry and water- containing brown coal
Zhang, Zhiqiang and Yan, Kefeng
MOLECULAR PHYSICS, 109, 2367-2374 (2011)
Moisture content of brown coal has a pronounced impact on O(2) diffusion during coal oxidation. The transport behaviour of O(2) in dry and hydrated brown coal matrix with 10, 20, and 30wt\% moisture contents have been studied by molecular dynamics ( MD) simulations at 298.15K and 0.1 MPa. By analysing the diffusion characteristics of O(2), it is found that the diffusion process results from jumps of O(2) molecules between adjacent cavities in the coal matrix. With the increase of moisture content, the swelling extent of coal matrix increases in the range of 10-30 wt\%, resulting in increased cavity volume, cavity interconnectivity, and mobility of coal macromolecule. These factors are all beneficial to the transport process of O(2) molecule. In addition, O(2) molecule prefers to reside in the available water-poor coal cavity and unoccupied region of water-rich cavity according to the estimated binding energies.
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