Ozone generation by negative corona discharge: the effect of Joule heating

Abstract

Ozone generation in pure oxygen using a wire-to-cylinder corona discharge reactor is experimentally and numerically investigated. Ozone concentration is determined by means of direct UV spectroscopy and the effects of Joule heating and ozone decomposition on the electrodes are analysed for different discharge gaps. The numerical model combines the physical processes in the corona discharge with the chemistry of ozone formation and destruction. The chemical kinetics model and the electrical model are coupled through Poisson's equation, and the current–voltage (CV) characteristic measured in experiments is used as input data to the numerical simulation. The numerical model is able to predict the radial distributions of electrons, ions, atoms and molecules for each applied voltage of the CV characteristic. In particular, the evolution of ozone density inside the discharge cell has been investigated as a function of current intensity and applied voltage.

A numerical study of species and electric field distributions in pulsed DBD in oxygen for ozone generation

“…Eliasson [14] employed 16 species and 70 reactions in his model and demonstrated that the excited species are essential in ozone production using a parallelplate DBD system. Yanallah [15] adopted 15 species and 38 reactions without ioneion recombination reactions to investigate the negative corona discharge in a wire-cylinder reactor. Moreover, only 4 species and 5 reactions were included in Loiseau's model to simulate the axial and radial distributions of ozone in a cylindrical ozonizer [16].…”

Numerical simulation of an oxygen-fed wire-to-cylinder negative corona discharge in the glow regime

“…5b). The structure of the electrical discharge is almost identical to the case of zero-flow rate [8], that is, the inter-electrode space appears divided in three regions: the ionization region, around of the cathode; the active region, where the electron density is maximum; and drift region, where the negative space charge accumulates. The transport of charge in the drift region is entirely due to O 2 − and O 3 − .…”

“…The experimental set-up is similar to the one used in previous works [8,9]. The corona discharge reactor consists of a smooth tungsten wire, with radius r 0 = 0.05 mm, placed along the axis of a stainless steel cylinder.…”

“…Boundary conditions appropriate for (5)- (8) have already been introduced in previous works [7,8,9]. Regarding charged species, the number density of negative ions must be zero on the corona wire (cathode), since it is subjected to negative high voltage.…”

“…In the past, the authors have also investigated the generation of ozone in wire-cylinder geometry using negative [7,8] and positive [9] corona. The electrical discharge was modeled as stationary and symmetrical around the corona wire, as done by other investigators [4,5,6].…”