【作者】 项里程；

【导师】 帅石金；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2004， 硕士

【摘要】 汽车排放问题越来越被世界各国政府所重视,日趋严格的排放法规的制定促进了发动机排放控制技术的发展。柴油机在稀燃富O2条件下工作,其NOx的排放仅靠机内净化的办法很难满足日益严格的排放法规要求,因此研究稀燃条件下降低柴油机尾气中的NOx后处理技术具有重要的意义。本论文在发动机台架上对以乙醇作为还原添加剂以Ag/Al2O3为载体的柴油机稀燃NOx催化剂进行了起燃特性和空速特性的性能评价,并通过欧III标准试验研究了该催化剂单独使用和分别与两种氧化催化剂组合使用时对NOx和HC、CO的净化效果,得出了组合使用该NOx催化剂和氧化催化剂才能使HC、CO和NOx同时降低的结论。本论文还对乙醇还原剂的加入提出一套优化控制策略。在进行优化控制的条件下,组合使用NOx催化剂和氧化催化剂,使原来只达到欧II排放法规要求的柴油机达到了欧III法规要求。利用发动机专用一维数值模拟软件Boost,对整个发动机工作过程进行了建模和仿真,分析了后处理系统对发动机的动力性和经济性的影响。更多还原

【Abstract】 With the rapid development of economy in the world, more and more attentions from the government and society are paid on vehicle emissions. The implementation of stricter emission standard promotes the development of the purification technology of engines. Since diesel engine runs in lean burn condition, it’s far from enough to make its NOx emission meet the stricter emission standard using only in-cylinder methods. So it’s very important to study after-treatment technology to purify the NOx emission of diesel exhaust in lean burn condition.In this paper the light-off and space velocity performances of diesel lean NOx catalyst composed of Ag/Al2O3 with ethanol as the reductant have been evaluated in the engine test bench. The purifying performances to NOx and HC, CO of this catalyst used alone and combination with two oxidation catalysts respectively have also been studied through Euro III standard test (ESC). A conclusion is drawn that diesel lean NOx catalyst must be used together with the oxidation catalyst to purify HC、CO and NOx simultaneously. A set of strategies to optimize the adding of the ethanol reductant has also been brought forward in this paper. In the condition of optimization, the diesel engine which originally only met Euro II can meet the requirement of Euro III, using the combination of the NOx catalyst and the oxidation catalyst.In the environment of 1D numerical simulation software Boost, the model of the whole engine working process has been established and the influence of the exhaust after-treatment system to the performance of power and economy of the engine has been analyzed.更多还原