The formation and structure of the dust cake on the surface of air filters have been investigated theoretically and experimentally. A novel experimental setup was developed to perform in situ measurement and monitoring of the dust cake height, pressure drop, and the challenge aerosol concentration and size distribution. Test aerosols included the Arizona Road Dust (AC fine), alumina particles, and talc particles. A CCD camera was used to observe and measure the increase of cake thickness with time. The cake mass at a specific time was inferred from the measurement of the final cake mass and the total collection time. A new analytical equation, including the effects of polydispersity and shape-factor of the particles, was derived to correlate all the parameters involved. The equation gives dust cake structure (porosity) as a function of operating conditions (pressure drop and filtration velocity), particle characteristics (particle size distribution and particle shape), and the cake layer thickness. Results for different particle types used in the experiments show a good correlation using the derived equation. The study finds significant effect of polydispersity and shape-factor of dust particles on filter loading.
Bibliographical noteFunding Information:
This research is partially supported by the Center for Filtration Research at the University of Minnesota. Center members include 3M company, AAF International, Donaldson Company, Fleetguard, Honeywell, TSI, and W.L. Gore and Associates, We would also like to thank Professor Y. Kou-saka for his support and encouragement of Dr. Endo's sabbatical leave at the Particle Technology Laboratory, University of Minnesota.
- Dust cake loading
- Particle polydispersity
- Shape factor