Aerosol generation using a joint vapor–nuclei type generator: Factorial design to characterize its performance

Abstract

The performance of a joint vapor–nuclei type aerosol generator was investigated using a 24 factorial design experiment. The generator produced stable, reproducible monodisperse aerosols with aerodynamic diameters from 0.79 to 3.1 µm. The geometric standard deviation (GSD) ranged from 1.09 to 1.31. The factorial design experiment indicated that atomizer flow rate and temperature of aerosol material were the significant factors that control the number mean diameter (NMD) of product aerosols, while the diameter of the condensation chimney had a significant effect on aerosol monodispersity. Among these significant factors, the generator had a rapid, reproducible response to atomizer flow rate. As a result, it was used as an adjustment parameter to fine-tune the performance of the generator. Its main effect on NMD was –1.3 µm per increase of 1.0 L/min in atomizer flow rate. Experimental results suggested that a power-law relationship could be used to predict the NMD of product aerosols. This study confirmed that the atomizer must produce >105 cm–3 of primary mists to generate monodisperse aerosols by heterogeneous condensation. Key words: aerosol generator, monodisperse, condensation, nuclei, factorial design, heterogeneous, homogeneous.