Abstract:

The effect of particle density on the porosity of packed bed was studied by the experiment of the resistance characteristics of packed bed with cylindrical particles of different lengths of 3 mm and 4 mm. According to the experimental results, the following conclusions can be drawn that the porosity of the packed bed of cylindrical particles is independent of the particle density and is only related to the aspect ratio of the cylindrical particles.The modified model of the porosity of cylindrical particles packed bed was developed to make the prediction more accurate at high sphericity. The existing research results still have contradictions in predicting the cylindrical particle packed bed under different L/D values. And the Nemec model has higher prediction accuracy than the Wu model. When d_ep is used as the equivalent diameter, the R² of Ergun constants are 0.92(C₁) and 0.98(C₂), respectively, which is highest compared with that of other equivalent diameters.

Key words: granular materials, packed bed, porousmedia, pressure drop, cylindrical particles

摘要：

通过直径为3、4 mm不同长度的圆柱颗粒填充床的阻力特性实验，研究了颗粒密度对填充床孔隙率的影响，结合文献孔隙率数据修正了孔隙率模型使其在高球形度时预测更准，分析了等效直径的计算方法对Ergun常数的影响，得到圆柱颗粒填充床的阻力特性并与Nemec和Wu的阻力预测模型进行对比，提出新的拟合方法对Ergun常数进行拟合。结果表明：颗粒密度在1156~7947 kg/m3范围内对填充床的孔隙率没有影响；结合文献数据得到圆柱颗粒填充床的孔隙率修正模型；文献中预测不同L/D的圆柱颗粒堆积床的阻力时结果相差较大，Nemec模型要比Wu模型预测准确度高，但也不适用所有L/D下的阻力预测；结合圆柱颗粒填充床孔隙率提出新的拟合方法，拟合Ergun常数时，采用d_ep作为等效直径的拟合优度最高；提出新的Ergun常数表达式，适用于圆柱直径3~4 mm，L/D=1~10的圆柱颗粒，相比于Nemec模型其R²更高，适用范围更明确，因此实用性更强。

关键词: 颗粒物料, 填充床, 多孔介质, 压降, 圆柱颗粒