An Experimental Study of Thermophoretic Deposition of Aerosol Particles in Laminar Tube Flow with Mixed Convection

Abstract

The thermophoretic deposition of aerosol particles in mixed-convection, laminar tube flow with a cooled wall is considered. The presence of free convection alters the velocity and temperature profiles for laminar tube flow relative to the constant-properties case. Previous modeling results (Walsh, Weimer, and Hrenya, in press), show that the modified flow fields lead to changes in the cumulative deposition-efficiency profiles (i.e., deposition as a function of axial distance). In particular, deposition in vertical, downward flow is higher at short axial distances as compared to the upward counterpart, while overall deposition efficiencies (i.e., total deposition in the tube) for both cases are closer in magnitude. In this study, experimental data is obtained in an attempt to qualitatively and quantitatively validate the model predictions for the effects of free convection on cumulative deposition efficiencies. To explore the effects of free convection, two cases are considered: (1) comparison of systems w...