【作者】 赵永亮； 冯妍卉； 张欣欣；

【Author】 Yongliang Zhao;Yanhui Feng;Xinxin Zhang;School of Mechanical Engineering,University of Science and Technology Beijing;Beijing key laboratory of Energy Saving and Emission Reduction for Metallurgical Industry,University of Science and Technology Beijing;

【机构】 北京科技大学机械工程学院； 北京科技大学冶金工业节能减排北京市重点实验室；

【摘要】 本文从Wiser烟煤分子模型构建出发,使用巨正则蒙特卡洛(GCMC)和分子动力学(MD)方法,尝试通过热动力学因子将微观自扩散系数与宏观传递扩散系数建立联系,并利用传递扩散系数来研究CO2/CH4在煤微孔中的扩散特性,考察了温度的影响,并计算相应的扩散活化能。主要结论包括:1)单种气体的热动力学因子随温度的升高而降低;在同一温度下,CO2的热动力学因子大于CH4。2)在自扩散系数、校正扩散系数、传递扩散系数中,传递扩散系数与实验值吻合较好,验证了传递扩散系数对于描述煤微孔结构内的扩散特性的正确性。3)三种扩散系数均随温度的升高而逐渐增大;从阿累尼乌斯定律出发,计算了扩散活化能:CO2(36.40 k J/mol)小于CH4(38.34 k J/mol),说明CO2的扩散过程比CH4的更易发生。本文研究可以反映气体在煤微孔材料中的扩散机理,并为二氧化碳驱采煤层气工程提供理论指导。更多还原

【Abstract】 In this work, based on the Wiser bituminous coal model, a thermodynamic factor is introduced to associate microscopic self-diffusion coefficient with macroscopic transport diffusion coefficient by molecular simulation method(Molecular Dynamics simulation and Grand canonical Monte Carlo). Then transport diffusion coefficient is first performed to study the properties of CO2 and CH4 diffusion in coal micropores. The effect of temperature was analyzed and diffusion activation energy was also calculated. The results shows that: 1) the calculated thermodynamic factor decreases with rising temperature and the factor of CO2 is higher than CH4. 2) Among the self-, corrected and transport diffusion coefficients, transport diffusion coefficient is in better agreement with the experimental diffusion coefficient, which demonstrate that the transport diffusion coefficient is superior to other coefficients to describe the properties of gas diffusion in coal micropores. 3) Diffusion coefficients increase with rising temperature. From the classical law of Arrhenius, The calculated CO2 diffusion activation energy(36.40 k J·mol-1) is smaller than CH4 diffusion activation energy(38.34 k J·mol-1). The work can reveal mechanism of gas diffusion in coal micropores and provides some fundamental data for CO2-ECBM projects.更多还原