Comparison Between the Theoretical and Experimental Performance of a Differential Mobility Analyzer with Three Monodisperse-Particle Outlets.

Differential mobility analyzers (DMAs) with more than one monodisperse-particle outlet can offer a number of advantages compared to conventional single monodisperse-particle outlet de-signs. A generalized theoretical model and experimental measure-ments describing the performance of a DMA with 3 monodisperse-particle outlets have been independently reported in the literature. The objective of this article is to compare the theoretical predic-tions with the measurements. Resolutions determined by the theo-retically predicted transfer functions for the three monodisperse-particle outlets are compared with measurements when the DMA was operated under different operating conditions. Predictions and measurements show good agreement when the DMA is operated at low sheath flow rates and for aerosol outlets relatively far from the aerosol inlet. For aerosol outlets relatively near the inlet there is evidence that the discrepancy between theoretical predictions and measurements may disappear at higher sheath flow rates, but the chances of flow disturbances in the classifier increase as well. The theory for multiple monodisperse-outlet DMAs is thus seen as suc-cessful in predicting the performance of this instrument, provided that disturbances in the flow field are avoided. [ABSTRACT FROM AUTHOR]