Low-temperature soot incineration of diesel particulate filter using remote nonthermal plasma induced by a pulsed barrier discharge

Regulations regarding automotive diesel engine emissions become more severe every year, and it is difficult to meet the requirements with only combustion improvement techniques. More effective post-processing technology is desired especially for particulate matter (PM), such as carbon soots. Although the use of a ceramic diesel particulate filter (DPF) is now a leading technology for PM removal, the problem exists for the soot removal or regeneration at low temperature, especially at cold start and engine brake operation. In the present study, a regeneration of a DPF is investigated using indirect or remote nonthermal plasma (NTP) method. The NTP-treated air is injected into exhaust gas, and the NO is oxidized to NO₂. The induced NO₂ and activated oxygen species are used to incinerate carbon soot deposited on the DPF. It is confirmed experimentally that the pressure drop decreases when the plasma is turned on and the regeneration of the DPF is possible at the low temperature of 300°C. The specific energy density is 22 Wh/m³ (= 78 J/L). Although the condition of the NTP is not optimized in the present study, further improvement is required in the energy efficiency.