Effect of Inhomogeneous Electric Field on Filtration Characteristics of Solid Particles in Oil

Numerous factors can lead to the presence of solid particles in hydraulic fluid, which degrades the stability and service life of mechanical systems. Therefore, effective filtration of solid particles is crucial to maintain such systems. Although a uniform applied electric field can remove most of the solid particles from oil, it is inefficient in removing particles of relatively small size (d _p < 30 μm). Compared to a uniform electric field, a nonuniform electric field offers advantages including directional manipulation capability and higher local field strength. Capitalizing on these advantages, this paper proposes a multigradient filtering method based on the application of a nonuniform electric field. A mathematical model of nonuniform electric-field-enhanced oil-solid separation was developed by combining the equations for the electric field, flow-field control, particle-wall collisions, and discrete phase tracking. The solutions are used to investigate how the electric-field strength and inlet flow rate affect the filtration efficiency of solid particles in oil and the desolidation of an oil-solid filter augmented by the application of a nonuniform electric field. The results show that the application of a nonuniform electric field to the oil-solid system increases the filtration efficiency from 36 to 51%. When E _S > 1 kV/mm, the velocity of fine particles (d _p < 30 μm) increases with increasing electric-field strength. The maximum deposition density is 2.21 times greater than in the absence of an electric field, and the deposits are more dispersed. The filtration efficiency decreases with increasing inlet flow velocity (u _inlet) but not to less 40%.