空气中沼气的迁移和输运

本文用亥姆霍茨函数论证了重力场中大气压下沼气和空气自由混合后,其混合物是非均匀的,并利用Fick定律和重力场中的压力分布函数求出了沼气浓度的分布函数;给出了用Chapman-Enskog公式计算沼气在空气中的扩散系数的计算结果,并讨论了扩散系数与温度、压力和浓度的关系;求出了呆滞空间沼气传质方程的解析解,据此阐述了沼气积聚的空间、时间概念;应用湍流混合理论分析了沼气层和风流相对运动的混合效应,并给出了最小混合风速的理论计算式。

The Migration of Methane in Mine Air

In this paper by means of Helmholtz function, it is proved that the mixture is non-uniform when methane and air in gravity field are freely mixed under atmospheric pressure. The distribution function of methane concentration is optained by means of Fick's law and the pressure distribution function in gravity field. The method for calculating methane diffusion coefficient by Chapman-Enskog formula is given. The relationship between diffusion coefficient and temperature, pressure, methane concentration is discussed, and the analytical solution of mass transfer equation of methane in dead corner is obtained. Thus the conception of accumulation space and time is expounded. The paper analyzes the mixing effect of methane layer and airflow in relative motion and gives the theoretical formula for calculating the minimum mixing air velocity.