NO_x diesel exhaust treatment using a pulsed corona discharge: The pulse repetition rate effect

The pulsed corona offers real promise for degradation of pollutants in gas and water streams. This paper presents a study of NO_x removal from diesel exhaust. Special emphasis is laid on the investigation of the dependence of the NO removal rate and efficiency on the pulse repetition rate (PRR). A nanosecond solid state power supply (45 kV, 60 ns, up to 1 kHz) was used for driving the corona reactor. A Mitsubishi 10 kW 3-cylinder diesel-generator engine with a total volume of 1300 cm³ was used as a source of exhaust gas. At an NO removal rate of 35% the NO removal efficiency was 53 g kW^-1h^-1 for PRR ≤ 500 Hz and the initial NO concentration was 375 ppm. A semi-empirical expression for the corona reactor removal efficiency related both to PRR and to the residence time is presented. The removal efficiency decreases with increasing PRR at constant flow rate or constant residence time. This expression demonstrates reasonable agreement between the calculation results and the experimental data.