Numerical simulation of an electro-cyclone for classification of micron-sized particles

Cyclones are normally used to separate relatively larger particles from the aerosol. In this article, the feasibility of using cyclone to classify particles in specific mass range by applying an electric field between the outer cylinder and the vortex finder is studied. Moreover, the effect of cyclone geometry and the magnitude of the electric field on the cyclone efficiency and the classified particle diameter is quantified. FEM was used for the simulations of 3-D, steady and two-phase flow. It should be noted that the Reynolds number of inlet flow ranged between 4,000-10,000. The results reveal that the diameters of inner and outer cylinders have negligible effects on the cyclone efficiency. However, an increase in the length of the cyclone specifically the length of the vortex finder can significantly affect the cyclone performance which can be attributed to the higher particle residence time within the cyclone. For cyclones with twice larger cylinders, the classification efficiency is 6% - 17% higher based on the geometric standard deviation of the particle size distribution. It was also shown that different particle masses can be classified by adjusting the flow rate of the inlet aerosol or the magnitude of the electric field applied to the charged particles.