Design and Development of a Two-Stage Virtual Impactor for Size-Selective Sampling of Aerosol Particles

Abstract

Recently, the need to improve the performance of solar and fuel cells has been growing rapidly. With this has come, an increasing need for classification and size analysis of micro and nanoparticles. There is also growing interest in fine dust, which is the main cause of environmental pollution, and there is consensus on the severity of the problem. A virtual impactor can be used to sample and classify these particles. Owing to its simple design and low cost of production for such purposes, it is widely used today. However, virtual impactors have a number of disadvantages associated with wall losses and contamination with small particles, which affect their performance. Furthermore, conventional virtual impactor cannot be used to classify particles with a small or monodisperse size distribution. Therefore, a study was conducted to obtain monodisperse particles with high efficiency and low cost using aerosol technology. To classify aerosol particles by size, a two-stage virtual impactor was developed with various particle cut-off sizes at each stage that were connected in series in one housing. The housing was made of acrylonitrile butadiene styrene (ABS) because of its low cost and sufficient strength, and its design and characteristics were evaluated using CFD modeling. A stream of clean air was introduced into the center of the aerosol stream to reduce fouling of small particles contaminations in the minor flow. The ratio of the aerosol flow to the flow of clean air was calculated so that it did not affect the efficiency of the selection, but was also sufficient to solve the problem of fine particles contaminations in the minor flow at both levels. The ratio of the total flow to the minor flow was taken as 0.1 at both stages.