Multi-scale Simulation Study On Filtration Performance And Structure Optimization Of Pleated Air Filter Media

Pleated filter media,as an efficient dust treatment medium,has been widely used in industrial ventilation and dust removal equipment,automobile filter,and household air purifier,because of its large filtration area,high filtration efficiency and low energy consumption.Nowadays,people pay more and more attention to environmental protection and human health.The performance research and structure optimization of pleated filter media are of great significance for controlling the content of fine particles in the environment.In this study,mesoscopic three-dimensional mimicry physical model and macroscopic three-dimensional physical model of pleated filter media were constructed.Based on the computational fluid dynamics(CFD)and discrete element method(DEM),the influence of structural parameters of pleated filter media on its filtration performance was studied,and the parameters correlation between meso scale and macro scale was explored.The distribution law of air flow in pleated filter media was analyzed,and the pressure drop was summarized.The deposition process of particles in pleated filter media was observed,and the influence of fiber characteristics on particles deposition was discussed.The results show that:(1)The fiber arrangement and media thickness of pleated filter media will affect the pressure drop.But its influence on the properties of pleated filter media,such as solid volume fraction and viscous resistance coefficient,can be ignored.Therefore,the solid volume fraction and viscous resistance coefficient of pleated filter media can be calculated based on the proportional relationship between filtration velocity and pressure drop in mesoscopic scale,so as to provide data support for the performance research of pleated filter media.This further shows that there is a data transfer relationship between the meso structure and the macro structure of pleated filter media;(2)Compared with the experimental data,it is found that the mathematical model of pressure drop of pleated filter media summarized in this study is true,reliable and has practical application value.Based on the mathematical model,it is found that there is an optimal structure of pleated filter media to minimize the pressure drop,and the optimal pleated angle is about 35 degrees;(3)Under the combined action of air flow and particle force(including adhesion force),the deposition process of particles not only changes the porosity of the medium,but also affects the physical structure of the medium surface.The pressure drop of pleated filter media increases with the mass of deposition particles.Due to the agglomeration of particles and the formation of "dendrite structure",a multi-layer "particle wall" will be formed at the junction of the area of pleated angel and the middle area of the pleat.The "particle wall" will prevent the particles from further moving in the fluid domain without being damaged,which makes the area of pleated angel be divided into "low efficiency" parts of particles deposition;(4)The arrangement and the position of fibers not only have a great influence on the air distribution in the pleated air medium,but also have a guiding effect on the deposition of particles in the fibers.The optimization of fiber arrangement and fiber position will play an important role in the performance optimization of pleated filter media.