Abstract Number: 646 Working Group: Aerosol Modeling
Abstract Glowing wires generate charged nanoparticles via electrical heating which have been used earlier in association with mobility classification, but the phenomenon is complex and not fully understood. C. Peineke, A. Schmidt-Ott1 explained generation of negative particle charge by thermoemission of electrons and positive particle charge by surface ionization of impurity atoms with low ionization energy. Such impurities are inevitably present even in high-purity metals. The role of charge, for such conditions, via coupled flow aerosol dynamical equation has not been studied. Our previous work discusses CFD coupled aerosol microphysics model (without charge) in context of aerosol generation from a glowing wire. In the present work, we have added particle charge to aerosol dynamics sub-modules (ion-induced nucleation, charged particle coagulation2, electrostatic dispersion2) along with Navier Stokes equations. The model is also suitably modified to include buoyancy coupled K-Epsilon turbulence scheme. Coupled flow-aerosol dynamics equation was solved numerically and in implicit scheme. Wire composition and temperature (wire surface and cell domain) were obtained/measured, to be used as input for the model simulations. The aerosol dynamics scheme has been tested for charged aerosol particles by model studies against published results and the complete model was validated against measured temporal evolution of total number concentration and size distribution at the outlet of hot wire generator cell.
Model simulations showed significant effect of fluid properties and charge on aerosol dynamics if charge level is higher than the Boltzmann equilibrium charge limit for less than 1 µm particles. Experimental results have been compared with model simulations made for unipolar as well as bipolar charge distribution function. Although tuned specifically for the present context (i.e. aerosol generation from hot wire generator), the model can also be used for diverse applications e.g. emission of particles from hot zones (chimneys, exhaust), fires and atmospheric cloud dynamics.
References 1. C. Peineke et al. Journal of Aerosol Science 39 (2008) 244 – 252.
2. K. Ghosh et al. Journal of Aerosol Science 105 (2017) 35–47.