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[摘要]：The aim of this investigation is to clarify the effects of bioethanol on the combustion and exhaust emission characteristics, as well as the spray and atomization characteristics of bioethanol diesel blended fuels in a single-cylinder diesel engine. The spray and exhaust emission characteristics are analyzed using the spray visualization system, the droplet analysis measuring system, and the single-cylinder diesel engine with an exhaust emission analyzer. In addition, the effects of exhaust gas recirculation (EGR) on the emission characteristics are also investigated. In the analysis of the experimental results for the spray characteristics, it revealed that the spray tip penetration of bioethanol-blended diesel fuel shows almost similar behavior compared to a pure diesel fuel and the blended fuels show a wide spray cone angle, before the impingement to the piston bowl wall. In the case of the bioethanol blends, the mean reduction percentage of the droplet size increases as the bioethanol blending ratio increases when compared to the droplet size of a pure diesel fuel. In the results of combustion and exhaust emissions, the increased bioethanol blending ratio extends the ignition delay because of the low cetane number and the reduction of the cylinder temperature by the evaporation of bioethanol with high latent heat. The application of EGR induces the extension of the ignition delay and lowers both the peak combustion pressure and the peak rate of heat release (ROHR). The blending of bioethanol with diesel fuel causes a small decrease in soot emissions. Also, the use of EGR and blending bioethanol with diesel fuel can reduce nitrogen oxide (NOx) emissions. However, increasing the bioethanol blending ratio causes hydrocarbon (HC) emissions to increase. |
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