封闭空间内煤粒瓦斯解吸实验与数值模拟

Coal particle gas desorption experiment and numerical simulation in enclosed space

为研究瓦斯在煤粒中流动的基本规律,设计了封闭空间内的煤粒瓦斯解吸实验,分别以菲克和达西定律为基础,建立了该条件下煤粒瓦斯放散的数学模型,通过有限差分的方法进行离散并编制程序进行解算,最终实验和数值模拟都得到了4种粒径的煤样在不同初始压力下累积解吸量随时间的变化关系。根据实验和模拟结果分别绘制ln[1-(Qt/Q∞)2]-t关系图进行对比,结果表明:在菲克模拟中,无论扩散参数B如何变化,其结果始终为一条直线;而达西模拟和实验结果有明显的曲线特征并且两者拟合度较高,说明在封闭空间内煤粒中的瓦斯流动更符合达西定律。结合以往研究可知,无论外部压力变化与否,瓦斯在煤粒内的流动都服从达西定律而不是菲克定律。

In order to study the basic law of gas flow in coal particle,the coal particle gas desorption experiment in enclosed space was designed. Respectively based on Fick and Darcy law the mathematical models of gas emission in coal particle were established under this condition then the Finite Difference Method was used to discrete and the program was made to calculate. Finally the change relationships between the accumulated desorption amount and the time under different initial pressures of the coal samples with 4 particle sizes were obtained through experiment and simulation. According to the experimental and simulative results the ln[1-( Qt/ Q∞)2]-t figures were respectively drawn to compare. The results show that in Fick simulation no matter the diffusion parameter B how to change,the results are always some straight lines while the Darcy simulative and experimental results have obvious characteristics of the curve and a higher fitting degree,which demonstrates that gas flow of the coal particle in enclosed space accords with Darcy law better. Combined with previous studies,it can be got whether the external pressure changes or not,the gas flow in coal particle obeys Darcy law instead of Fick law.