Particle Deposition in Aerosol Sampling Lines Caused by Turbulent Diffusion and Gravitational Settling
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A model is presented for prediction of particle penetration through transport lines that are at arbitrary angles of inclination with respect to the vertical direction. There are, in the literature, previously reported models which describe the deposition of aerosol particles caused by either gravitational settling or turbulent deposition; however, a solution to the problem of combined gravitational and turbulent deposition has not been reported, ostensibly because of a special constraint which couples the two depositional mechanisms. Results of the analyses show there is an optimal inside diameter for inclined transport lines (Dopt) that is independent of tube length but depends upon particle diameter (Da), flow rate (Q), and angle of inclination. Aerosol penetration gradually decreases for tube sizes greater than Dopt, but it decreases dramatically for tube sizes less than Dopt. Therefore, in selecting a tube size, it is recommended the value be somewhat greater than Dopt (e.g., 1.25 Dopt). For horizontal tubes, the computational results for Dopt(Da, Q) have been fitted to a power law curve, and the results show Dopt = 1.75 Q°47 Da°21. Here Q must be in units of L/min; Da in units of jum; and Dopt in units of mm. Copyright 1989, American Industrial Hygiene Association
author list (cited authors)
ANAND, N. K., & MCFARLAND, A. R.