Abstract:

Porous particles used in combustion or catalysis were made by random walk method. The fractal characteristics of the porous particles are close to that of real ones. Based on the particle model, gas diffusion was investigated in the porous particles. Diffusion control equations were established according to the kinetic theory of gases and statistical thermodynamics. The effect of pore characteristics on gas diffusion was analyzed. The relationships between the specific area, average pore diameter and porosity with the diffusion coefficient were obtained. The results indicate that the gas diffusion coefficient decreases with the increase of specific area of pores. Gas diffusion coefficient increases as a power function of average pore diameter, and the exponent that represents the sensibility decreases linearly with the increase of porosity.

摘要：

采用随机行走方法建立了分形多孔介质生成模型，生成的颗粒在形貌上与真实多孔颗粒接近，且能够反映其固有分形特征。在此模型基础上，根据经典分子动理论建立扩散控制方程，对气体在多孔介质中的扩散进行数值模拟。分析了比表面积、平均孔径、孔隙率等孔隙特性参数对扩散的影响，获得了分形多孔介质中气体扩散系数与平均孔径的函数关系。结果表明，扩散系数随平均孔径的增大以幂函数形式增大，相应的指数表征扩散系数对平均孔径的敏感度，其值随孔隙率的增大呈线性减小。