Inertial separation of ultrafine particles by a Laval nozzle type supersonic impactor

• Published in: Powder technology Vol. 118; no. 1-2; pp. 188 - 192
• Main Authors: Kanaoka, Chikao, Chutmanop, Jarun, Kitada, Masayuki
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 08-08-2001; Elsevier
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology; Impactor; Inertial separation; Laval nozzle; Liquid-liquid and fluid-solid mechanical separations; Miscellaneous; Supersonic; Ultrafine particle; Impactor; Supersonic; Laval nozzle; Ultrafine particle; Inertial separation; Supersonic flow; Stokes parameter; Suspended particle; Aerosols; Experimental study; Performance; Particle separation; Submicron particle; Inertial separators
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/S0032-5910(01)00310-2

Separation of ultrafine particles by inertial effect in a supersonic flow field has been experimentally studied. The experiment was carried out in a Laval nozzle with different configurations. As a result, the cut size was found to decrease as Mach number increases, i.e., gas velocity becomes faster and the smallest cut size by this experiment has an aerodynamic diameter of about 0.04 μm at Mach number of about 2.8, which is about one order of magnitude smaller than that of conventional impactor. It is also much smaller than the performance of so-called low-pressure impactor and a fairly clear difference was observed among the configuration of nozzle and clearance between nozzle outlet to collection plate. Separation efficiency of the present impactor was evaluated by a Stokes number Stk and was found to increase very steeply against Stk, which is much steeper than the obtained separation curve for conventional impactor operating under atmospheric pressure.