Total diesel emission control system using ozone injection and plasma desorption

The authors reported a new diesel soot incineration technology using a combination of nonthermal plasma and DPF, and a new aftertreatment technology of NO_x included in exhaust gas of combustion system using nonthermal plasma desorption and reduction. Our proposed total diesel emission control system includes these new two technologies. In this system, the plasma reactor is located outside the emission exhaust pipe and radical gas induced from ozone activated by the plasma is injected into the exhaust pipe. This is called indirect or remote nonthermal plasma method first proposed by the authors for cleanup of diesel panrticulate and NO_x. It is confirmed in this study that the particulate removal or DPF continuous regeneration is possible using the indirect oxygen-rich remote surface discharge plasma. On the other hand, the NO_x reduction is achieved using oxygen-poor nonthermal plasma desorption. The concentration of oxygen can be changed either by controlling the incineration state of the engine or by injecting oxygen-poor gas. Experiments are carried out for the emission of small diesel engine generator and high performance is demonstrated. The effective or apparent required plasma energy can be decreased further using this system because of the periodic or intermittent application of the plasma. In the present study, the reduction energy efficiencies of 6.6 g/kWh for PM and 10 g (NO)/kWh for NO_x are achieved. These are realizable electric power values to meet the recent Japanese new long-term national regulation for diesel automobiles.