Abstract
Removal of nitrogen oxides (NOx) from diesel engine’s exhaust gas has become essential issue because of the more and more stringent emission legislations. NOx removal using discharge field has been studied for years and showed its potentiality. In this paper, NOx removal by a dielectric barrier discharge was investigated experimentally. A mixture of N2, NO and O2 was used as test gas and its composition depended on purpose of certain experiment. NO concentration was kept constant at 100 ppm while O2 fraction is changed from 0 to 20%. To understand the effect of residence time, the gas flow rate was varied from 0.5 to 2 l/min. A diesel particulate filter (DPF) was put in discharge field as a dielectric barrier. The applied voltage was adjustable up to 15 kV. The concentrations of gases were measured by FT-IR exhaust gas analyzer. The experimental results showed that NO concentration reduced to zero and total NOx concentration decreased 44% under condition of applied voltage was 12 kV, gas flow rate of 0.5 l/min, test gas was mixture of 100 ppm NO, 10% O2 and N2 left. In addition, the effect of particulate matters (PM) to NOx removal characteristics was also investigated. The DPF containing 100 mg of PM was used. The results in cases of DPF with and without PM showed that PM promoted NOx removal reactions in dielectric barrier discharge field and PM composition was changed in trend to reduced soluble organic fractions and sulfate.
Keywords: NOx, Diesel exhaust, Dielectric barrier discharge, Diesel particulate filter