CIRCUMFERENTIAL SLOT VIRTUAL IMPACTOR FOR CONCENTRATING AEROSOLS

摘要

A circumferential slot virtual impactor includes a disk-shaped housing (18) with an endless circumferential slot (40) for receiving aerosols. The slot forms an acceleration nozzle (36), and a receiver nozzle (48) spaced apart radially inwardly from the acceleration nozzle exit. In an annular gap (42) between the two nozzles, negative pressure is selectively applied to draw a major flow of the aerosol axially away from the nozzles, while a minor flow of the aerosol is drawn radially inward and enters the receiver nozzle (48). A portion of the larger particles leaves the major flow and merges with the minor flow due to particle momentum, thus increasing the large-particle concentration of the minor flow. The acceleration nozzle (36) incorporates convex curvature (44, 46) along its opposed interior surfaces, for a smoother aerosol flow and reduced large­particle deposition.