Search Results

Dielectric barrier discharge (DBD) offers the advantage to excite and dissociate molecules in the exhaust gas stream. Those dissociated and excited species are oxidizing or reducing harmful exhaust gas components. The advantage of a plasma chemical system in comparison to a catalytic measure for exhaust gas treatment is the instantaneous activity at ambient temperature from the starting of the engine. The investigations reviewed in this paper are dealing with the plasma chemical oxidation of hydrocarbons in the exhaust gas stream during cold start conditions. The article concerns the design and development of a plasma-system in order to decrease the hydrocarbon emissions from engine start till catalyst light off. Vehicle results in the New European Driving Cycle show a hydrocarbon conversion of more than 42% in the first 11 seconds from engine start. In this period nearly all types of hydrocarbon were reduced.

Dielectric barrier discharges offer the advantage to excite molecules to reaction processes on a low temperature level in an O2 containing exhaust gas of gasoline or diesel engines. With the aim of a flexible coaxial reactor and a compact and efficient generator the influence of geometric and electric parameters on the reduction of exhaust gas components was determined. Geometric parameters studied were gap width, length, contour of the reactor. Electric parameters were: voltage curve, voltage height, frequency and electric power. Using the advantage of low temperature reactions it was possible to reduce the HC emission of a gasoline engine by about 35% within an electric power of 1000 W.