Experimental Comparison of Four Differential Mobility Analyzers for Nanometer Aerosol Measurements

Abstract

The performance of four differential mobility analyzers (DMAs), namely the TSI-long, the TSI-short, the Hauke 3/150, and the Spectromètre de Mobillte Electriqué Circulaire (SMEC) were evaluated under the same conditions of flow rates, flow ratio, input monodisperse aerosols, and transport-line lengths. The evaluations were performed under the conditions of 10 1/min sheath air and 1 1/min aerosol flow rates, and at a flow ratio of 10:1. Monodisperse aerosols in the size range of 6 nm to 50 nm were obtained by classifying condensation aerosols using a Hauke DMA operated at 20:1 flow ratio. The transfer functions of all four DMAs have been obtained by deconvoluting the scan results of the evaluated DMA (DMA2), and by using the empirical transfer function of the first DMA (DMA1, the Hauke DMA at 20:1 flow ratio). The half-width, height, and area of the transfer functions have been compared for the four DMAs tested. These results provide a quantitative comparison of the mobility resolution and diffusion loss of the nanometer aerosols in the DMAs.