Particle deposition from aerosol flow inside a T-shaped micro-mixer

  • Author: M. Heim, R. Wengeler, H. Nirschl and G. Kasper
  • Source: Journal of Micromechanics and Microengineering, 2006, 16, 70-76
  •  A T-shaped micro-reactor was used to mix a particle laden gas stream (an 'aerosol') and a clean gas stream, here with the objective of determining particle losses to the inside walls of the reactor (and hence the potential for clogging) as a function of operating conditions. Losses were determined with established on-line concentration measurement techniques, using monodisperse sodium chloride particles and vitamin-E-acetate droplets of variable size range between 10 and 700 nm. Measured losses range between 10 and 95%, depending on flow rate and particle size, and can be modeled with the particle Stokes number. CFD and particle trajectory modeling confirm that particle impact on the walls of the inlet and the mixing zones is the predominant particle deposition mechanism, induced by the local, sharp curvature of streamlines. The modeling points to ways of optimizing the inlet geometry of the mixer to reduce impaction losses significantly.