Filtration mechanism of filter material-03

Author : filterworkshop.com

Update time : 2019-12-31 13:41:16

Filtration mechanism of filter material-03
7- Porosity
The void ratio, that is, the structure of the filter material has a direct impact on the filtration efficiency. This is another reason why the structure of needle punched filter material is more suitable for dust purification than that of ordinary fabric. The following table shows the influence of various mechanisms on the filtering effect.

influence factor	Smaller fiber diameter	Decrease in inter fiber velocity	Gas filtration speed decreases	Increase of dust particle size	Dust density increases
Gravity action	No influence	No influence	reduce	increase	increase
Screening effect	increase	increase	No influence	increase	No influence
Inertia effect	increase	increase	reduce	increase	increase
Hooking effect	increase	increase	No influence	increase	No influence
Diffusion effect	increase	increase	increase	reduce	reduce
Electrostatic interaction	reduce	increase	increase	reduce	reduce

8-capture of unsteady filtration
According to the time series, the filtration process of filter media can be divided into two stages: stable filtration and unstable filtration.

In the stage of stable filtration, it is assumed that the change of filter cloth structure caused by particle deposition is ignored, and particles are trapped in contact with fibers without considering the modification of filtration mechanism. Therefore, the efficiency of filtration is not affected by filtration time. With the increase of filtration time, the particles gradually formed on the surface of the fiber lead to the generation of unstable filtration stage. The change of the void ratio of the filter cloth and the chain deposition of the particles are conducive to the improvement of the fiber collection capacity, which leads to the increase of the collection efficiency with the increase of filtration time and particle deposition.
In the actual filtration process, with the increase of time, the shape and size of the fiber have obvious changes.
The collection efficiency of unsteady filtration process is a function of fiber filling density, fiber diameter, single fiber collection efficiency, filtration speed, initial concentration of dust particles, total deposition quality of dust particles and filtration time.

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