混合气的氧燃比和温度对富氧燃烧柴油机PAH、碳烟和NO_x排放和燃烧路径的影响

Effects of Mixture’s Oxygen-Fuel Ratio and Temperature on PAH,Soot and NOxEmissions and Combustion Paths of Oxygen-Enriched Diesel Engine

构建了包含PAH和NOx反应的正庚烷氧化反应动力学详细组合模型,并对其进行了验证.以该组合模型为基础,开展了混合气的氧燃比(R)和温度(T)对富氧燃烧柴油机排放和燃烧路径影响的理论计算工作.结果表明,所构建的组合模型是可信的,可以用来对柴油机的燃烧和排放特性进行预测.富氧燃烧柴油机有害排放物PAH、碳烟和NOx受混合气的氧燃比和温度的影响显著,其生成规律在R-T图中呈"半岛"型分布.在R-T图中,富氧柴油机的燃烧路径有别于传统柴油机,导致其PAH和碳烟排放降低,而NOx排放增加.最后,为了降低富氧燃烧柴油机的NOx排放,提出了两种富氧燃烧路径的控制策略.

A detailed combined model for n-heptane oxidation including PAH and NOx reaction is achieved and verified. Based on the combined model, the effect of oxygen-fuel ratio （R） and temperature （T） of mixture on emissions and combustion paths of oxygen-enriched diesel engine is studied. The results show that the combined model is reliable and can be used to predict the combustion and emission characteristics of diesel engine. The harmful emissions of oxygen-enriched diesel engine, such as PAH, soot and NOx, are significantly influenced by the oxygen-fuel ratio and temperature of mixture, which shows a ＂peninsula＂ distribution in R-T figure. In R-T figure, the combustion path of oxygen-enriched combustion is different from that of the traditional diesel engine, which results in the decrease of PAH and soot emission, but the increase of NOx emission. Finally, in order to reduce the NOx emissions of oxygen-enriched diesel engine, two control strategies of oxygen-enriched combustion path are put forward.