Simultaneous phenomenon of particle deposition and reentrainment in charged aerosol flow — effects of particle charge and external electric field on the deposition layer

Formation of a particle deposition layer has been investigated as a simultaneous phenomenon of particle deposition and reentrainment in a turbulent aerosol flow. Aerosol particles passed through a corona charger were pneumatically transported into a glass tube equipped with a ring-type electrode. The deposition layers formed on the tube wall under various conditions were then quantitatively analyzed with particular attention to the effects of particle charge and external electric field on the deposition layer. The charged particles formed a filmy deposition layer around the electrode independent of the polarity of the particle charge and applied voltage. The mass of the deposition layer increased with elapsed time and became constant after an equilibrium state of particle deposition and reentrainment had been achieved. The time dependence was represented by an exponential equation; the time constant decreased with increasing particle charge and/or applied voltage, and the equilibrium mass of the deposition layer increased with particle charge. Furthermore, it was found that an appropriate arrangement of electrodes to control external electric field eliminates the filmy deposition layer.