Effect of relative humidity on electron distribution and ozone production by DC coronas in air

Summary form only given. A numerical model of electron distribution and ozone production in clean and humid air by DC corona discharges from a thin wire is presented. The model is based on the prior models of ozone production by DC coronas in dry air, with modifications to incorporate the effect of water vapor on the electrical characteristics and the chemistry of the discharge. The water vapor present in air affects the corona initiation field strength, the mass and the mobility of ions, and the plasma chemistry (e.g., production of OH radicals). The distribution of electron number density is obtained by solving coupled continuity equations for charge carriers and the Maxwell´s equation. The electron kinetic energy distribution is solved from the Boltzmann equation. The electron distribution data is then combined with the chemical mechanisms of ozone formation in humid air and the transport phenomenon to obtain the rate of ozone production. The predicted ozone production rates are compared with experimental data available in the literature. The effect of relative humidity on the electron distribution and ozone production is examined, together with the effects of discharge polarity, discharge geometry (flow direction and wire size), operating current, air temperature and flows residence time.