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研究论文

姚春德,李云强,王银山,段峰,吉庆.用柴油/醇组合燃烧法在城市车用柴油机上实现同时降低碳烟与NOx排放的研究[J].环境科学学报,2004,24(5):828-833

Study on the simultaneous reductions of PM and NOx by using diesel/alcohol compound combustion mode in diesel engines for city bus

摘要：柴油机在部分工况采用柴油扩散燃烧, 另一部分工况则采用柴油引燃醇燃料形成的均质混合气压燃燃烧.这种组合燃烧利用醇的高汽化潜热和含氧特性, 达到同时降低柴油机碳烟及氮氧化物(NO^x)排放的目的, 并可以避免小负荷燃烧醇燃料带来的高醛类排放问题.在一台485QDI直喷式柴油机上采用上述组合燃烧法进行了试验, 醇均质混合气经进气管处喷射形成, 用电控装置控制醇燃料喷入量及其喷入时刻.试验结果表明, 与原机相比, 碳烟和NO^x排放分别可以减少50%和30%以上, 同时燃料的消耗率也有大幅度降低.该方法为降低城市车用柴油机的碳烟排放提出一个新的解决途径.

Abstract：A new compound combustion mode is proposed, which is composed of two stages of the combustion occurring in diesel engine. At the first stage, the engine adopts conventional diffusion combustion with diesel fuel at low load, starting as well as warming up periods. At the second stage, the engine utilizes Quasi-HCCI (homogenous charge compression ignition) formed by alcohol mixture ignited by diesel fuel at other operating conditions. Making full use of the characteristics of high latent heat vaporization and high content of oxygen in alcohol, the compound combustion mode was applied to diesel engines not only to simultaneously reduce the soot (PM) and NO_x emissions from the engines, but also to dramatically decrease the aldehyde emissions. The experiments were carried out on a model of 485 QDI engine, which was a direct injection, naturally aspirated, water-cooled diesel engine with 4 cylinders. The ethanol or methanol mixture was formed through an injector with low pressure mounted at intake manifold of the engine. Both the amount and time of alcohol injection were controlled by an electronic control unit. The experimental results showed that with the compound combustion mode, the soot and NOx emissions from the engine were decreased by more than 50% and 30% respectively, and the engine fuel economy was also improved compared with the conventional mode. The compound combustion mode demonstrated a new approach of decreasing PM of diesel engines for city buses.