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Technical Paper

Emissions from Diesel Vehicles with and without Lean NOx and Oxidation Catalysts and Particulate Traps

The regulated and non-regulated emissions of a current diesel passenger car and two light-duty diesel trucks with catalysts and particulate traps were measured to better understand the effects of aftertreatment devises on the environment. The passenger car, a 1.8 L IDI TC Sierra, was tested both with and without three different diesel oxidation catalysts (DOC) and with two fuel sulfur levels, 0 and 0.05 wt%. One light-duty truck, a 2.5 L DI NA Transit, was tested on one fuel, 0.05 wt% sulfur, with and without three different particulate trap/regeneration systems and with and without a urea lean NOx catalyst (LNC) system. A second similar Transit was tested on the 0.05 wt% sulfur fuel with an electrically regenerated trap system. The results are compared to each other, regulated emission standards, and to emissions from gasoline vehicles.
Technical Paper

Diesel Additive Technology Effects on Injector Hole Erosion/Corrosion, Injector Fouling and Particulate Traps

Fuel additives can contribute to maintaining the performance of diesel engines in a variety of ways. This holds true for current and future engine technology. Fouling of indirect injection engines (IDI) has been studied at length. Fouling of direct injection engines (Dl) is less known and less well understood. Problems associated with Dl fouling and a proposed mechanism for it are discussed. Additive effectiveness in preventing injector fouling is confirmed. Injector hole corrosion/erosion, as experienced in the Cummins N14 engine, can be avoided by the appropriate additive chemistry. Particulate traps can also benefit from ashless additive technology aimed at increasing the time between regeneration steps, hence improving effective trap life.
Technical Paper

The Description of the Regeneration Behavior of Diesel Particulate Traps with the Aid of a Mathematical Model

Monolithic ceramic filters, suitable for reducing particulate emissions to within the 0,2 g/mile emissions limit, are intermittantly loaded and regenerated. A mathematical model was developed in order to describe the processes which take place in the filter during regeneration. The basis of the calculation model, such as reaction kinetics, heat and mass transfer, energy and mass balance, and flow performance are explained. Filter temperature, soot oxidation and exhaust flow behavior are described over the length of a filter channel. A calculated and measured regeneration sequence for an engine operating point near engine full load are illustrated and compared. The results show that due to the prevailing higher temperatures, an intensified soot oxidation occurs at the rear of the channel.
Technical Paper

Cold Start Emission Reduction by Barrier Discharge

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.