Novel in-line aerosol impactor utilizing upward inlet flow

This study demonstrates an our newly designed novel in-line real impactor, which is operated at the inlet flow rate of 1.0 L/min and has vertical annular nozzle to separate particles larger than 20.5 µm in the aerodynamic diameter. The Stk50 for an impactor with a rectangular nozzle was selected as the design parameters of the impactor. The influences of both existences of an orifice and distance between orifice and impaction plate are investigated numerically and experimentally. In numerical simulations, Stk50 of an impactor without an orifice is found to be 20.5% and 17.0% larger than that of an impactor with an orifice when the distance between an orifice and the impaction plate is 1.2 mm and 1.8 mm, respectively. For the impactor with an orifice, the Stk50 is predicted to decrease from 0.74 to 0.43 when the distance between orifice and impaction plate was decreased from 1.8 mm to 1.2 mm with an orifice. It is found that the pressure drop of the impactor with an orifice is at most 2.35% larger than that of the impactor without an orifice. Thus, the presence of an orifice can increase the pressure drop slightly but increase collection efficiency significantly. For our newly developed impactor, the collection efficiency of is primarily influenced by the distance between an orifice and the impaction plate. In experiments, the Stk50 was decreased from 0.50 to 0.25 when the distance between orifice and impaction plate was decreased from 1.8 mm to 1.2 mm. The Stk50 obtained from experimental data shows the same tendency as numerical predictions