Improvement of Stability for NO Removal in Multipoint Barrier Discharge Reactor by Pulse Applied Voltage

Improvement of stability for NO removal in dielectric barrier discharge (DBD) reactor by pulse applied voltage is described in this paper. Two different types of power supply are used to drive the DBD reactor. The ac type power supply produces a sinusoidal waveform at 10 kV in amplitude and 10 kHz in frequency. The pulse voltage of 10 kV is generated by a full-bridge type pulse modulator using insulated gate bipolar transistor (IGBT) switches. A duty factor of the pulse voltage is controlled in the range from 10 to 80% with a gate signal of the IGBT switches. A multipoint electrode is used in the DBD reactor for low voltage drive. NO gas is diluted with nitrogen and oxygen gas mixture (N-2:O-2=9:1) and is fed to the DBD reactor. About 80% of NO is removed with energy efficiency of 13 g/kWh at 150 ppm initial NO concentration in the case of sinusoidal voltage. The energy efficiency for 100 ppm NO removal is decreased from 13 to 10 g/kWh with increasing initial NO concentration from 150 to 500 ppm. However, the energy efficiency is almost independent of initial NO concentration in the case of pulse applied voltage. The input energy of the reactor increases from 2.06 to 4.84 mJ with increasing initial NO concentration from 100 to 500 ppm at 6.5 kV in applied sinusoidal voltage. The increments of the input energy are 41 and 137% for the pulse and the sinusoidal voltages, respectively. NO removal is almost independent of duty factor of the pulse applied voltage. The power loss consumed in the pulse modulator is reduced by decreasing the duty factor without decrement of NO removal efficiency.