| Summary: | 碩士 === 國立中正大學 === 機械系 === 89 === With diesel engines, fuel is sprayed directly into the cylinders at the time combustion isintended to occur. Diesel fuel injection systems operate at high pressures, on the order of 100 MPA. There are also diesel injection systems that use a positive displacement pump so that the mass injected is the independent variable and the fuel pressure adjusts itself accordingly.
In this study we present a brief review of diesel engine emissions, which consist maily of smoke, particulates, odor、NOx、CO、and unburnt HC, they are controlled by fuel-air mixing. The fuel injected into the combustion chamber of a diesel engine undergoes pyrolysis and creates a precursor element from the pyrolysis components. These elements from precursors that could be aromatic. The aromatic structure grows due to nucleation reaction and forms condensed-phase materials, which subsequently absorber high-molecular-weight hydrocarbon compounds. The parent aromatic hydrocarbon can also undergo fragmentation which yields CHx、C2Hx、C3Hx、polycyclic aromatic hydrocarbons (PAH) etc., which in turn form soot particles.
This study is using a set of equipment for the testing diesel oil that is under some operational conditions, the pressure、temperature、the mass of fuel and injection time are controlled by us. With the pressure variation data, the effect of pyroster on the combustion characteristic can be understood to explain the emissions modification. This study provides the better understanding of mechanisms of thermal pyroster on the diesel engine emission, with the combustion analyses the better pyroster’s conditions can be systematically studied for engine engine emission.
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