Experimental Investigation and Simulation of the Filter Performance of Compressed Electret Nonwovens

During nonwoven filter media manufacturing, compression occurs over the entire media surface. Further processing of the medium, e.g. pleating, leads to additional local compaction. This causes variations in the local flow resistance and particle capturing which affects the global filter performance, i.e. pressure drop, filtration efficiency, and dust holding capacity.

This work offers a modeling framework to investigate the influence of compression on media characteristics for both flat and pleated filter media for air filtration. The efficiency model also includes the electrostatic charging of fibers (so-called electret media), providing a higher aerosol retention rate than uncharged nonwoven fabric while maintaining the same flow resistance.

The pressure drop modeling is based on the Darcy-Forchheimer equation and the efficiency modeling on the single fiber efficiency theory. The model calibration is exclusively based on experimental data for flow resistance and filter efficiency in the uncompressed state of the filter nonwoven fabric. The proposed models can be used in numerical studies to assess the initial efficiency and long-term performance of pleated media.