DIFFUSION FORCES ON AEROSOLS

The separation of particles with radii smaller than 1 mu m by means of migration induced by concentration gradients is considered. An experi mental set-up consisting mainly of a measuring tube was used for the e xperimental investigations. The separating capacity could be enhanced from virtually zero in the absence of a concentration gradient up to 6 0% with a concentration gradient for particles with diameters of 0.135 mu m. The separating capacity was enhanced for larger particles from 25% to nearly 100% due to diffusion forces. The particle path in the m easuring tube was calculated in order to compare these results with kn own results. Concentrations and velocities in the tube were calculated by means of a finite element program. The theoretical and experimenta l results are in good agreement.