Particuology 8 (2010) 28–36 Contents lists available at ScienceDirect Particuology journal homepage: www.elsevier.com/locate/partic Jet dispersion and deposition of charged particles in confined chambers Chao Zhu a,∗ , Dawei Wang a , Chao-Hsin Lin b a Department of Mechanical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA b Environmental Control Systems, Boeing Commercial Airplanes, Seattle, WA 98124, USA article info Article history: Received 25 February 2009 Accepted 18 March 2009 Keywords: Charged particle deposition Confined chamber Electric field Jet dispersion abstract Dispersion and surface deposition of charged particles by gas–solids jets in confined chambers are con- stantly encountered in many industrial applications such as in electrostatic precipitation and dry powder coating processes. Understanding and control of flow patterns and trajectories of charged particles are important to the optimal design and operation of such devices. In this study, modeling of flow fields and particle trajectories of dilute gas–solid two-phase flows with charged particles in confined chambers is performed. The dilute gas–solid two-phase flows are simulated by use of a hybrid Eulerian–Lagrangian approach with the one-way coupling between the gaseous phase and particle phase. The space charge distribution is included as a source term in equations of motion or Lagrangian equation of charged par- ticles, which in turn depends on the particle trajectories that determine the space charge distribution. Our modeling predictions suggested that the electrostatic charge plays a significant role in particle radial dispersion. Effect of voltage has limited influence on particle trajectories however it can have a big impact on the residence time. Cone angle has a significant effect on the structure of flow field. For cone with a larger cone angle (typically over 15 ◦ ), there will be a flow separation along the side wall near the flow entrance region. By comparing with the conical chamber, the cylindrical chamber has a big vortex and three smaller vortexes in the lower part of the chamber, which would complicate the particle dispersion with or without the coupling of charging. © 2009 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. 1. Introduction The phenomenon of the electrification of solid particles is com- plex. In gas–solid flows, surface contact by collisions, ion collection, and thermionic emission are known to be the major modes of par- ticle electrification. Electrostatic deposition is widely utilized in many industrial applications, such as the office copying machine that requires pre- cise deposition of ink particles on predefined spaces, electrostatic precipitators that remove charged aerosols from the gas streams, and drug distribution processes which utilizes electrostatic princi- ples to convert a bulk drug powder into a finished dosage form (i.e., a “tablet” or “capsule”). The gas–solid flow field can be significantly affected by the electrostatic forces induced by the charge-carrying particles. Charged particles thus migrate to the collecting plate due to the Coulomb force as well as under the influence of momentum interaction with the gas flow in terms of aerodynamic drag (Choi & Fletcher, 1998). ∗ Corresponding author. Tel.: +1 973 642 7624. E-mail address: zhu@adm.njit.edu (C. Zhu). The phenomenon of turbulent particle dispersion in electro- static precipitators has been widely investigated. The motion of charged particles suspended in the gas stream was previously stud- ied without considering the effects of particulate space charge (Meroth, Rastogi, & Schwab, 1996; Watanabe, 1989), which can significantly change the electric potential and the charge density distribution, especially when the particles are heavily loaded. Some other studies (Cristina & Feliziani, 1995) considered the effect of particle space charge in the calculation of electric field and current density distribution while assuming the particle concentration is a simple function of distance from the inlet of gas–solids flow. Choi and Fletcher (1998) investigated the particle motion by strong cou- pling of hydrodynamic equations of ions, gas and particles with the effects of particle space charges and particle charging pro- cess. In the applications of powder coating, the combination of electric and aerodynamic forces on charged powder particles is specially designed and controlled to improve the film thickness distribution on a grounded substrate or target and to increase the transfer efficiency. Mathematical modeling and numerical simula- tion approaches of study on electrostatic painting processes are performed to examine the influence of the electric field on the spray pattern (Ali, Base, & Inculet, 1994; Ellwood & Braslaw, 1998; 1674-2001/$ – see front matter © 2009 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.partic.2009.03.012