Multipoint barrier discharge process for removal of NOx from diesel engine exhaust

We investigated the application of the dielectric barrier discharge process to the removal of NOx from exhaust gas of a 20-kVA diesel engine generator. A multipoint-to-plane geometry was used as an electrode for low-voltage operation. A pyrex glass plate with a 2-mm thickness was put on the plane electrode as the dielectric barrier The reactor consists of six discharge cells, with each cell consisting of five stacked multipoint-to-plane electrodes where the exhaust gas flows with a high flow rate. The exhaust gas was successfully treated at a flow rate of 1.2 m(3)/min. In order to produce repetitive high-voltage pulse, we made two switching electronic devices, an insulated gate bipolar transistor (IGBT), and a pulse transformer. This pulse modulator supplied the voltage with peak value of 10 kV and repetition rate of 2.5 kp/s (pulses per second) to the reactor. The energy transfer efficiency of the pulse modulator is 65% at 300 W of the power consumed in the reactor. The NOx (NO + NO2) in the exhaust gas was reduced by 35 ppm with an electrical efficiency of 32 g/kWh.