A Self regenerating diesel emissions particulate trap using a non-thermal plasma

There is great concern about the adverse effects associated with exposure to diesel exhaust. There is increasing evidence that diesel exhaust particulate matter (PM) is carcinogenic and may cause cancer. Non-cancerous lung damage and respiratory problems are also associated with exposure to diesel exhaust as well as acid rain and smog. Diesel exhaust PM is very easily respirable once emitted into the atmosphere and therefore poses a significant health problem. A diesel engine emissions particle removal system which utilizes Electrostatic Precipitation (ESP) and Non Thermal Plasma (NTP) technologies was studied for trapping and oxidizing micron sized particles (0.01 to 10 microns) in the exhaust. Particles are first charged in a mono polar manner in a NTP in the diesel exhaust stream, and then collected on an electrically grounded precipitation surface. Gaseous radicals produced in the NTP oxidize the precipitated particles to provide a continuously regenerating system. This device is targeted to help meet recently instituted US Environmental Protection Agency (EPA) Tier II as well as upcoming European (Euro 4, 5) and Japanese diesel particulate emissions standards. This system can be coupled with a suitable catalyst or other emissions treatment technologies to produce a complete exhaust aftertreatment system. Analytical and empirical methods were used to model the proposed Self Regenerating Diesel Emissions Particulate Trap. The analysis showed that a total particle precipitation efficiency of greater than 95% could be obtained using less than 0.5% of total engine energy output at a vehicle speed of 120 km/hr for a compact diesel powered vehicle. It was determined that the energy requirement for producing gaseous radicals in the exhaust stream is higher than is needed for particle charging and precipitation. It was also determined that the conversion of radicals can be accomplished using less than 2% of the total engine output. The results of the model developed shows that the proposed device would be effective reducing diesel PM emissions on a heavy-duty vehicle