| The energy and environment problems become increasingly the focus of attention with the world car ownership growing rapidly. In recent years, the theory of efficient clean combustion was researched in-depth with the fuel consumption and emissions rules and regulations got strictly. Researches have indicated that premixed compression ignition has the potential to realize efficient clean combustion. Because of the less volatile of traditional diesel fuel, a large number of particles formed in the local high temperature oxygen-depleted area,leading to the ultrafine particle emission increasing.Therefore,the research of realizing the premixed compression ignition combustion model by optimizing the fuel’s characteristics has the important theoretical and practical significance.In this study, a particle diameter analysis platform and Gas chromatography analysis platform have established with a high-pressure common-rail diesel engine; a exhaust sampling system based on the circulation was designed and developed. wide distillation range fuels of different physical and chemical properties were confected by adding different proporting of gasline into European IV diesel fuel. Researched the particle diameter distribution characteristics of wide distillation range fuels. Injection parameters were adjusted precisely by electronically controlled high pressure common rail fuel injection system.The influence of the wide distillation range fuel and combustion boundary conditions on combustion process and particle size distribution was researched with a compression ignition engine. The results had indicated that the characteristics of fuel have a significant influence on combustion process particle size distribution. With the increase of gasoline blending proportion in the fuel, ignition delay period extended, the combustion phase delayed accordingly, the diffusion combustion turned into premixed combustion, the proportion of premixed increased, the number of accumulation mode particles and smoke reduced, the curve peak of Particle size distribution shift to the small particle size, When the proportion of gasoline was too high, it would lead to incomplete combustion and lower thermal efficiency. Considering the combustion efficiency, the more appropriate proportion of gasoline volume was40%. EGR contributed to prolonged ignition delay period, which could increase premixed combustion by mixing the fuel and air more uniformity. For diesel fuel, when EGR rate was over22%, the combustion process gradually presented the premixed combustion, accumulation state particles increased slightly, nuclear particle number decreased. But for wide distillation range fuel, the accumulation state particles number increased monotonously with the increase of EGR rate, and nuclear particles number reduced significantly. Improving the fuel injection pressure was helpful to reduce the number of accumulation state particles, but it had little influence on the particles of wide distillation range fuel. Wide distillation range fuel helped to improve the problem of insufficient intake due to the lag of the supercharger intake in transient conditions, and improved particulate emissions of the transient process.The result of analyzing the components of exhaust HC in steady and transient operating conditions with wide distillation range fuel, the proportion of gasoline in blended fuel had obviously influence on the composition of SOF, and it had different influence under different load conditions. Under medium operating condition, the proportion of SOF from fuel reduced; under high load operating condition, it was rising. In addition, the proportion of methane and ethylene of HC emissions was above60%. And in transient process, the proportion of the above two kinds of gaseous HC reduced first, and the decreased. Under the transient condition, the proportion of the methane and ethylene increased with the gasoline proportion increasing. |
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