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Energy conservation and emission will be deemed to develop a subject for internal-combustion engine, and PM could be reduced, power output and fuel economy is increased by oxygen-enriched combustion, but NOx emission is raised simultaneously, so a turbocharged diesel engine is used as an expeimental study of oxygen-enriched combustion technology. In this paper, a new controlling means is applied by the combination of oxygen-enriched combustion and EGR technology together, a stable oxygen-enriched intake air system is planned,a dependable EGR system is also designed,moreover, combinations between defferent oxygen concentration of intake air and defferent EGR rate is principally studied, at the same time, effective specific fuel consumption and maximum output power is also considering. The experiment from different combinations, that major oxygen concentration is 21%,22%,23%,24%, EGR rate is 20%,35%,45%,50%, is compared with oxygen-enriched intake air test or original machine test.The results of experimental research show that smoke of diesel engine is significantly reduced following the increase of oxygen concentration from 21% to 24% in intake air, on the contrary, NOx emission is rising suddenly, because oxygen-enriched intake air enhances cylinder pressure and temperature of being beneficial to NOx producing; and effective specific fuel consumption is slightly down following the oxygen concentration, but maximum output power is adding, and it has an average growth rate of 0.8%, as every 1% increase in oxygen concentration of intake air from 21% to 24%.As an optimum combination within the bounds of oxygen concentration from 21% to 24%, and EGR rate from 20% to 50%, it may bring down the smoke and NOx emission. Compared with original machine, diesel engine mostly have a good smoke than it, especially the decreasing rate may reach about 80.0% within oxygen concentration of 24% and EGR rate 20% at full load mode of 2200r/min; and NOx emission is partially lower than original machine by combination, particular the decreasing rate may reach about 56.7% under oxygen concentration of 21% and EGR rate 50% at full load mode of 1600r/min; then effective specific fuel consumption and maximum output power is in keeping with original machine in EGR rate from 20% to 45%, however, it is maximal for effective specific fuel consumption to reach about 10%, and maximum output power is related to working condition from 45% to 50%. It is practical through combined action between oxygen-enriched and EGR to reduce smoke and NOx emission simultaneously, in addition, also to keep in step with original engine for dynamic characteristies, economic. In particular the combination of oxygen concentration of 21% and EGR rate 20%, oxygen concentration of 22% and EGR rate 50%, smoke and NOx emission is respectibely reduced about 20.0%and 14.8%,6.7% and 19.2% than original diesel engine.
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