Effect of particle electrostatic charge level on collection efficiency of an electric metal mesh filter

The effectiveness of filter media technique for air purification is no longer a matter of debate. However, the challenge now is to determine ways of optimizing particle-fiber interactions in order to achieve the optimal balance between particles collection efficiency and pressure drop across the filter. In this paper, we are particularly interested in interactions of an electrical nature, governed essentially by Coulomb, dielectrophoretic (DEP) and image forces. At first, we developed a special experimental protocol that enabled us to focus mainly on these interactions. Then, by controlling particle charge levels, we were able to dissociate the contribution of each force on collection efficiency and to explore parameters influencing them, such as particle and wire diameters, mesh size, inter-grid distance and electric field intensity within an Electric Metal Mesh Filter (EMMF). The results revealed that the contribution of Coulomb force to collection efficiency is the most important, particularly in the case of strong field and high charge level. The efficiency by DEP force increases with field intensity, particle diameter and decreasing fiber diameter, whereas the effect of inter-grid distance and mesh size were limited. As for image force, its impact on collection efficiency increases with particle charge, although it remains marginal. • Novel protocol was developed to separate collection mechanisms contributions. • Particle electric charge identifies the dominant electrostatic force. • For slightly charged particles, the dielectrophoretic force predominates. • At high particle charge levels, the Coulomb force becomes dominant. • The image force is only effective in collecting particles close to the fibers.