Effects of electric field on the filtration characteristics of solid particles in oil

The presence of solid particles in oil can easily lead to surface failure of machine components. In order to reduce the harmful effects of solid particles, it is necessary to remove solid particles from oil. The electrostatic method is an efficient method for removal of solid particles under an applied electric field. However, the filtration mechanism for solid particles in mixed oil–solid systems using electrostatic methods has not been fully investigated. In view of this, an oil–solid separation method based on electric field enhancement is proposed. For this method, a numerical model of oil–solid separation under different electric field strengths is established by coupling the electric and flow field governing equation, the particle-wall collision equation, and the discrete phase tracking equation. Solved by finite element method, the influence of electric field on particle motion and filtration performance of the system is studied. The results indicated that in the mixed oil–solid system, the filtration efficiency is significantly increased by more than 32.97% when an electric field is used. When E > 1 kV/mm, the flow rate of particles into and out of the filter increased with increasing electric field intensity, the deposition became more dispersed, the highest deposition concentration was 3.69 times that without an electric field, and the filtration efficiency decreases but does not exceed 10% as the flow rate increases. When the particle size is greater than 30 μm, the filtration efficiency increases by at least 14.71% for every 1 kV/mm increase in electric field strength, up to a maximum of 97.65%.