Characterization of pore size distribution of non-woven fibrous filter by inscribed sphere within 3D filter model

The pore size distribution of non-woven fibrous filter (NWFF) was characterized by inscribed sphere within 3D NWFF model created with straight fibers arranged randomly in a 3D calculation space. The size distribution of the inscribed sphere was employed as pore size distribution of the model NWFF. The effects of design parameters of NWFF, which are fiber diameter and porosity, on the pore size distribution were studied. It was shown that the pore size distribution was geometric similarity to fiber diameter. The pore size distribution curve normalized with fiber diameter was on peculiar to porosity. The number median diameter of the pore size distribution was compared with the pore sizes characterized with actual NWFFs by bubble point test, liquid permeation test, and particle challenge test. From these observations it was demonstrated that the number median diameter can be easily estimated from the porosity and fiber diameter without complex 3D simulation and it will be useful to predict the separation performance.