The effect of fibre configuration on the efficiency of aerosol filtration

Experimental investigations are carried out using model and real filters. A monodispersed aerosol, produced by a spinning top generator is used to test the filters, mass determinations being carried out by the sodium flame technique. Postulating, but not proving, that adhesion is responsible for the deviation between the theoretical results, based on the Rappel cellular flow model, and experimental results, agreement between theory and experiment is demonstrated. It is proved that model and real filters can be corrected for their deviation from ideal banks of parallel fibres, by utilizing their experimental drag characteristics. The filter efficiency is reduced at low values of air relative humidity, but increased by particle charge if the inertia parameter is small. Fibre configuration, as embodied in the packing effect, only slightly affects the single fibre efficiency in the inertial region. There is an increase in the single fibre efficiency between 1 and 3% packing, little effect between 3 and 9%, and further increase at 11%. Lack of particlefibre adhesion is postulated as explaining this phenomena.