Study On Improving Diesel Emissions By Using Nonequilibrium Plasma

With the development of technology and the living levels of people, environmental protection and sustainable development have become two of most important issues concerned by people and researchers. Automobile, as the major moving pollution source, is laid more emphasis on. Gasoline engine and diesel engine are two primary kinds of engines used in vehicles. Recently, the diesel engine is widely used than before and has gradually become the first choice for automobiles, because of its higher fuel economy and lower HC and CO emissions. However, the high NOx and PM (Particulate Matters) emissions slow down the development of diesel engines. In order to solve this problem and meet the stringent regulations, researchers investigated many emission control techniques to reduce these two kinds of emissions. The technique using plasma is a novel emission control method emerging in the 1990s. It is a multidisciplinary study area covering plasma physics, high voltage power supply, engine emission control, and chemical reaction dynamics, etc.In this thesis, the emission control technique by using nonequilibrium plasmas is investigated experimentally. Based on the analysis of chemical reaction mechanism, the different kinds of plasma reactors are compared and a novel wet needle-plate corona discharge reactor with rotary spark-gap switch high voltage pulse power supply is proposed. Simulation experiments using scientific gases and single cylinder diesel bench tests are conducted respectively. The relationship between the performance of the plasma reactor and NOx removal efficiency are investigated, and some useful conclusions are drawn based on the analysis and discussion of experimental results.