Modeling the surface filtration pressure drop of PTFE HEPA filter media for low load applications

Wanyi Zhang, Shiming Deng, Yongxiang Wang, Zhongping Lin

Research output: Journal article publicationJournal articleAcademic researchpeer-review

16 Citations (Scopus)


Recently, PTFE filters have been widely used in low load applications like industrial cleanrooms because of their low initial pressure drops, while little attention to their pressure drop growth has been paid in previous studies. In this study, surface filtration pressure drop models for PTFE media were established by evaluating the particle drag force in dust cakes, where the shielding effect between neighboring particles was quantitatively calculated using the kinetic theory. Dust loading experiments for PTFE HEPA membranes were conducted using monodisperse SiO2 with different diameters and polydisperse SiO2 with different geometric standard deviations, the pressure drops for PTFE membranes were real-time monitored. A novel on-site laser scanning porosity measuring system was built to accurately measure the changes in thickness and porosity of dust cakes. Experimental results showed that the thickness growth rate of a dust cake was gradually decreased with an increase in loaded dust mass and the porosity was linearly decreased consequently. The pressure drops for dust cakes formed by monodisperse SiO2 aerosols agreed well with those predicted by the monodisperse model after the diffuse reflection rather than specular reflection hypothesis was applied. Lower experimental results than the prediction by the polydisperse model could be explained by the aggregation effect inside the dust cake which led to a decline in the windward area of particles. The comparison between the models developed in this study and previous studies indicated the better applicability of the new-established models for surface filtration pressure drops of PTFE media for low load applications.

Original languageEnglish
Article number106905
JournalBuilding and Environment
Publication statusPublished - 15 Jun 2020


  • Dust cake porosity
  • Monodisperse SiO aerosol
  • Pressure drop model
  • PTFE membrane
  • Rigid-body diffuse reflection

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Building and Construction


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