纤维过滤滤饼孔隙率计算机模拟

Computer Simulation of Dust Cake Porosity in Fibrous Filtration

基于受限扩散模型，建立纤维介质表面粉尘颗粒沉积形成滤饼的模拟模型。粉尘颗粒在远离过滤介质的控制面上释放，假设对流扩散运动为颗粒输送和沉积的主要机理。定义Pe数为颗粒对流作用与扩散运动的比值，讨论不同Pe数对滤饼孔隙率的影响。对Pe数范围为O．25—1600进行模拟计算结果表明，Pe数对滤饼的孔隙率影响显著。当颗粒的扩散运动强于对流运动，颗粒沉积形成的滤饼为较为松散的结构，当Pe数较大时，颗粒沉积形成的滤饼为较为紧密的堆积结构。此外，考虑到实际过滤过程中粉尘颗粒大多为非等径粒子，也对多分散粒子对滤饼形成及孔隙率的影响作了分析。

A new developed simulation algorithm based on diffusion limited aggregation simulation techniques to simulate the cake formation and growth in surface falters at an individual particle level. In the model, the modeled aerosol particles were introduced from control window far away from fibers＂ surface. Convective diffusion was assumed to be the main mechanism of particle transport and deposition. The Peclet number, which defines the contribution of convective and diffusional effects on deposition, was used for analysis of an influence of both effects on the structure of dust cake. Local porosity of dust cake were calculated for the Peclet number ranging from 0.25 tol600. The simula- tion results showed that the Peclet number have a greater effect on the cake＇s structure. When the diffusional deposition of particles has stronger influence over a convective effect, cake has more loose structure than that obtained at the higher value of the Peclet number. In ad- dition, since the particle size in the suspension is likely to be no uniform in practical applications, The effect of size distribution on the structure of dust cake were also investigated.