On Thursday, December 13, 2018, Longwen CHEN, a doctoral student in Energy and Process Engineering at the Laboratory for Design Optimization and Environmental Engineering (LOCIE), will defend his dissertation titled “Experimental Study of Corona Discharge for Indoor Air Treatment: VOCs and Particles.”
The defense will take place at 10:30 a.m. in Lecture Hall 30, Building 3 (Pôle Montagne) on the Bourget-du-Lac campus.
Thesis summary
Indoor air quality has become a public health concern, largely due to the increase in the amount of time spent in indoor environments and enclosed spaces. The objective of this work is to develop processes utilizing corona discharge to treat chemical gaseous pollutants and particulate matter in indoor air. The first part of the study focuses on the degradation of chemical gaseous pollutants present in very low concentrations in indoor air. A combination of corona discharge and a catalyst is used to degrade toluene under conditions representative of indoor air. This study demonstrates the high efficiency of corona discharge for toluene at low energy densities. It identifies optimal operating conditions and proposes reaction mechanisms following the identification of the main reaction products. However, the plasma generates undesirable species such as ozone and nitrogen oxides, which must be destroyed. We chose to combine the corona discharge with a transition metal oxide-based catalyst (MnOx/Al2O3). Various catalysts are synthesized and then modified by grafting modifying agents. Their effectiveness against ozone and NOx is quantified in the presence of varying water vapor concentrations. The second part concerns particle collection via electrostatic filtration. Three processes are studied; they combine an ionization stage and a collection stage. Ionization is provided either by a wire-plate electrostatic precipitator or by needles charged to a potential of a few kilovolts. Collection efficiency is measured in the range from 10 nm to 20 µm as a function of various operating parameters (voltage, polarity, velocity, geometric parameters, particle concentration, humidity, etc.). The needles have slightly lower efficiency than the electrostatic precipitator but produce very little ozone and consume less energy. The parametric study allows for sizing, optimizing the process geometry, and defining the best operating conditions.