Suppression of particle deposition in tube flow by thermophoresis

Suppression of particle deposition from flow through a tube with circular cross-section was investigated numerically and experimentally for the case when the wall temperature exceeds that of the gas. Particle transport equations for convection, diffusion and thermophoresis were solved numerically to obtain particle concentration profiles and deposition efficiencies. The numerical results were validated by particle deposition efficiency measurements with monodisperse particles. For all particle sizes, the particle deposition efficiency was found to decrease with increasing tube wall temperature and gas flow rate. Particle deposition was suppressed completely when the tube wall was heated to a certain temperature slightly above that of the gas flow. An empirical expression has been developed to predict the dimensionless temperature difference needed for zero deposition efficiency in a laminar tube flow for a given dimensionless deposition parameter. (C) 2004 Elsevier Ltd. All rights reserved.