Collection efficiency of sintered ceramic filters made of submicron spheres

We have developed an experimental set up and methodology to evaluate the performance of sintered ceramic filters, with a high collection efficiency and high pressure drop. The system consisted of polydisperse NaCl particle generator, a DMA, an ejector and a mixing-type CNC. With this set up, the known size particles with a concentration of 10⁸-10⁹ particles/m³ can be fed into the rest filter, and filter penetration down to 10^-9 can be measured in the particles size range from 0.02 to 0.14 μm. The major difference between the present experimental filters and the available sintered ceramic filters is on the alumina particles size. Submicron-sized particles are used to make the tested filters. Two filters made from sintering alumina particles of 0.60 and 0.84 μm in diameter were tested. The experimental data reported in this paper can be used as the basis of further theoretical development. A single sphere theory based on the concept of the traditional single fibre theory was derived for the test filters. The filtration mechanisms of the diffusion and interception were included in the derivation. Compared with the experimental data, the theory in general reproduces the trend of the penetration curves for the parameters involved, e.g. particle size, filtration velocity, packed particle size. However, it is not sufficiently accurate for quantitative prediction of the filtration penetration of sintered ceramic filters.