多组分非理想气体扩散系数的改进

Modification of the diffusion coefficient of multi-component nonideal gas

现有方法对高压下多组分非理想气体的可压缩性和分子之间的交互作用考虑不足,不能准确反映各组分的扩散特征。针对该问题,基于PR状态方程对Fuller二元扩散系数以及热力学因子计算方法进行了校正,分析了气体压力、组成对热力学因子的影响,计算了三组分物系Fick扩散系数矩阵。结果表明:对于实际的多组分非理想气体,校正后的扩散系数计算精度显著提高;热力学因子表征了混合物实际状态偏离理想状态的程度,以及分子扩散方向与浓度梯度之间的关系,其值随着体系压力和气体组分的变化而变化,且与压缩因子变化趋势相同。多组分非理想气体扩散系数改进研究为探究多组分非理想气体在空气中的扩散奠定了理论基础。

Existing methods don’t take the compressibility and molecule interaction of multi-component nonideal gas under high pressure into consideration fully, so they cannot reflect diffusion characteristics of each component accurately.To solve this problem, the Fuller binary diffusion coefficient and thermodynamic factor calculation methods were modified based on the PR equation of state. Then, the effects of gas pressure and component on thermodynamic factor were analyzed.Finally, Fick diffusion coefficient matrix of three-component system was calculated. It is indicated that as for real multicomponent nonideal gas, the accuracy of the modified diffusion coefficient calculation method is increased significantly.The thermodynamic factor characterizes the deviation degree of real state from the ideal state of mixture and the relationship between molecule diffusion direction and concentration gradient. And it varies with the system pressure and the gas component and its variation trend is the same as that of compressibility factor. The studies on the modification of multicomponent nonideal gas diffusion coefficient lay the theoretical foundation for exploring the diffusion of multi-component nonideal gas in air.