Abstract To study the characteristics of gas diffusion and changes in the dynamic parameters of coal under a negative pressure environment, experiments were performed to constrain the desorption process under different negative pressures in coal samples at (0.5, 1.5 and 2.5) MPa adsorption equilibrium pressures. The experimental results demonstrate that the relation curves between time and the desorption quantities of coal samples with different negative pressures have shapes similar to that of Langmuir’s adsorption isotherm. In addition, all coal samples with different negative pressures have a maximum regarding methane desorption. As the negative pressure increases from 10 kPa to 40 kPa, the limitation gas desorption amount increases from 8.73 to 10.93 mL/g, from 14.91 to 17.75 mL/g, and from 18.30 to 23.27 mL/g, respectively, under 0.5 MPa, 1.5 Mpa and 2.5 Mpa adsorption equilibrium pressure. Moreover, under the same adsorption pressure, the larger the negative pressure becomes, the greater the gas desorption velocity of the first minute (V1) is. The change of gas desorption velocity with negative pressure during the first minute is an exponential function. The performance under different adsorption equilibrium pressures demonstrates the same regularity. With the increase of negative pressure, interfacial mass transfer resistance also decreases, and the diffusion coefficient and Fourier’s criterion of mass transmission increase. This indicates that the negative pressure environment changes the desorption kinetic-parameters of the coal mass and increases the amounts of methane desorption and desorption velocity, which are advantageous for desorption and diffusion of coal methane.

中文翻译：

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负压环境下煤中甲烷解吸扩散特征

摘要 为研究负压环境下煤样的气体扩散特性及动态参数变化，通过实验对不同负压下煤样在（0.5、1.5和2.5）MPa吸附平衡压力下的解吸过程进行约束。实验结果表明，时间与不同负压煤样解吸量的关系曲线具有与朗缪尔吸附等温线相似的形状。此外，所有具有不同负压的煤样在甲烷解吸方面都有最大值。随着负压从 10 kPa 增加到 40 kPa，在 0.5 MPa、1 . 5 Mpa和2.5 Mpa吸附平衡压力。而且，在相同的吸附压力下，负压越大，第一分钟的气体解吸速度(V1)越大。在第一分钟内气体解吸速度随负压的变化是一个指数函数。不同吸附平衡压力下的性能表现出相同的规律。随着负压的增加，界面传质阻力也减小，扩散系数和传质傅立叶判据增大。这表明负压环境改变了煤体的解吸动力学参数，增加了甲烷解吸量和解吸速度，有利于煤体的解吸和扩散。