Diesel particulate filter (DPF) are considered to be the most effective means to reduce particulate emissions, and the key of DPF lies in their regeneration. O3 and O which have strong oxidability can be produced by non-thermal plasma (NTP) reactor. PM can be decomposed by these active substances to generate CO and CO2. The results show that PM deposited in the DPF can be removed by NTP technology without any catalyst and DPF can be completely regenerated at a lower temperature.

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Characteristics of a water-cooled non-thermal plasma (NTP) reactor used to reduce diesel emissions were experimentally studied. The effects of working voltage, operating frequency and air flow rate on discharge power and concentrations of O3 and NO2 generated by NTP system were investigated at different surface temperatures of discharge zone. The experimental results show that, the discharge power of the reactor would increase with the increasing of working voltage, operating frequency and surface temperatures; air flow rate had little influence on discharge power; variation of O3 and NO2 concentration were different with the increasing of working voltage and operating frequency at different surface temperatures of discharge zone; when the surface temperature of discharge zone was constant, concentrations of O3 and NO2 increased firstly and then declined with the increasing of air flow rate; and concentrations of O3 and NO2 were higher at lower temperature.

By using self-designed non-thermal plasma reactor, the influences of discharge power, initial concentration of C3H6 and O2 concentration on NO pro-oxidation in C3H6/NO/N2/O2 mixture were studied. The obtained results indicate that with the increasing of discharge power, NO2/NOx ratio grows firstly and then decreases after reaching a peak value, while NOx conversion efficiency and N2O concentration gradually rise. Increasing initial concentration of C3H6 or O2 concentration would help to enhance NO oxidation efficiency. With the same discharge power, NOx conversion efficiency grows with the increasing of C3H6 initial concentration while reduces with the increasing of O2 concentration. Controlling the concentration of C3H6 and O2 in exhaust gas can lead the NO2/NOx ratio to reach 50%, which is benefit to NOx conversion with SCR system.