Influences of Fiber Geometry on the Performance of Nonwoven Air Filters

The effects of fiber cross-sectional shape on the filtration performance of nonwoven fabrics were examined empirically. Compared to round fibers, performance was better with fibers having three or four lobes but poorer with fibers having two lobes, Performance improved with lobe depth. Some of these results, which were obtained with small (10-cm diameter) patch filters, were con firmed by measurements made with a one-bag laboratory baghouse. The results obtained are similar to theoretical predictions of capture efficiency of lobed fibers in electric fields, and therefore it is proposed that the response of filter performance to fiber shape is partly electrostatic in origin. Some experimental support for this hypothesis is presented.