【作者】 周小松；

【导师】 郎静；

【作者基本信息】 华中科技大学 ， 动力机械及工程， 2006， 硕士

【摘要】 DME作为柴油机代用燃料的研究已经广泛兴起,但是目前主要侧重于柴油机性能和常规污染物的排放特性,也涉及到DME燃烧机理的研究;但是很少涉及到一些微量排放物(如甲醛、甲酸、甲酸甲酯等)的研究,更少有它们生成机理的研究。为了更好的控制柴油机的排放并为微量排放物生成机理的研究作准备,本文从从现有的废气采样系统着手,寻找既适合常规排放物(NOx、碳烃和CO)的取样,又满足微量排放物(甲醛、甲酸和甲酸甲酯)取样要求的取样系统,并用它做柴油机燃用DME的排放试验研究。最优化气相色谱仪测量甲醛、甲酸和甲酸甲酯的色谱操作条件,并用外标法标定色谱仪的FID检测器,在此基础上分析了柴油机燃用DME时常规和微量排放物的排放规律。试验发现FID检测器对甲酸的敏感度太低,不适合分析尾气中的甲酸含量,必须对甲酸进行预处理或采用新的检测器;试验还发现甲醛的排放量偏高。试验中的某些工况点检测到了少量的甲酸甲酯,说明甲酸甲酯的生成和柴油机特定的运行工况相关。为了分析常规排放物和微量排放物的排放规律,设计了转速、负荷、供油提前角、柱塞直径、起喷压力和喷孔直径六个因素不同水平的正交试验,并利用正交表的特性对试验结果进行了方差统计分析,找出了影响各组分排放的显著因素,确定了各组分的最优生产条件。试验发现正交试验和单次单因素试验的结果是一致的,且减少了试验的工作量。更多还原

【Abstract】 The research on DME as alternative fuel to diesel engine has risen in the world, but at present the engine performance and regular emissions are preferred to. Some studies investigate the combustion mechanism of DME, but a few is involved in the trace emissions such as formaldehyde, formic acid and formic ether, and none goes into their formation mechanism. For better emission control of diesel engine, this paper will find out an appropriate sampling system not only for regular emissions but also for the trace emissions from the existing sampling systems, and apply it on the emission test. After optimization of operating conditions on the trace emissions measurement by gas chromatography, calibration of FID by external standard method, we can find out the emission performance of diesel engine fueled with DME. The experimental results show that the FID is too insensitve to formic acid, and can’t meet with the requirements of measuring formic acid. Much higher formaldehyde emission than usual is observed, and at some working conditions a small amount of formic ether can be detected. Six factors’(speed, load etc.) orthogonal test is designed to find out the regular and trace emission trend. Statistic analysis is done by advantage of the orthogonal table, and from which the dominant factor and optimized conditions are worked out. The advantage of orthogonal test is that the same result to ordinary experiment can be achieved with less work.更多还原