【作者】 马鑫；

【导师】 裴毅强；

【作者基本信息】 天津大学 ， 动力机械及工程， 2009， 硕士

【摘要】 柴油均质充量压燃(HCCI)能有效降低颗粒物和NOx的排放,但由于HCCI燃烧与传统燃烧有本质区别,其微粒的生成机理及理化特性必将有所不同,同时,柴油机非常规污染物——多环芳香烃(PAHs)和羰基化合物的排放也备受关注。因此,开展对HCCI燃烧模式的微粒演化历程及其非常规污染物排放特性的研究显得尤为重要。本文以全气缸取样系统为基础,对HCCI燃烧中微粒的演化历程进行研究,同时运用气相色谱—质谱联用仪(GC-MS)和高效液相色谱仪(HPLC)分别对HCCI燃烧过程及尾气中的颗粒相PAHs和HCCI燃烧尾气中的气态羰基化合物进行检测分析,研究发动机工作条件对微粒的演化历程及非常规排放的影响规律。研究结果表明:1、在本研究的各种工况下,HCCI燃烧SOF占微粒的比例在整个燃烧过程和尾气中都很高,分别在54.6%～90.2%和42.5%～79.3%范围内变化,而传统燃烧只有15%～30%,HCCI燃烧微粒的这种排放特性为采用简单后处理技术(DOC等)进一步降低柴油机微粒提供可能。2、在本研究的工况范围内,HCCI燃烧过程中,除3环芳香烃以外,2、4、5环芳香烃的总质量峰值随负荷和转速的增大均降低。HCCI燃烧尾气中3环和4环芳香烃占PAHs的比例最大;总PAHs的比排放量以及各环的比排放量均随着进气压力的增大而增加;除2环芳香烃的比排放量随着负荷的增大而减少外,总PAHs的比排放量以及其余各环芳香烃的比排放量均随着负荷的增大而增加。3、在HCCI燃烧尾气中,14种羰基化合物中占总羰基化合物比例最大的是乙醛,其次是丙烯醛+丙酮,以及甲醛。4、HCCI燃烧在相同的EGR率及进气压力下,除甲醛的比排放量随负荷的增大而减少外,总羰基化合物、乙醛和丙烯醛+丙酮的比排放量均随负荷的增大而增加。在相同的EGR率及负荷下,总羰基化合物、甲醛、乙醛、丙烯醛+丙酮的比排放量都随着进气压力的增大而增加。在相同进气压力和负荷下,总羰基化合物、甲醛、乙醛和丙烯醛+丙酮的比排放量都随着EGR的增大而减小。更多还原

【Abstract】 Homogeneous charge compression ignition (HCCI) combustion of diesel enables internal combustion engines to achieve much lower particulate matter (PM) and NOx emission than conventional diesel engine. There are significant differences in formative and oxidative properties between PM produced from HCCI engines and traditional combustion method due to the existing essential distinctions in combustion modes. Besides, the unregulated emissions of diesel HCCI engine (include polycyclic aromatic hydrocarbons (PAHs) and carbonyl compounds) are of great concern as their potential health impacts. Therefore, experiments on a diesel HCCI engine were conducted to examine the characteristics of PM and unregulated emissions in HCCI combustion.In-cylinder particulate processes, particle phase PAHs and gaseous carbonyl compounds in diesel HCCI engine were systematically studied using an exclusive total cylinder sampling system followed by a gas chromatography-mass spectrometer (GC-MS) and a high-performance liquid chromatography (HPLC). Effect of operating conditions on the PM evoluaiton processes and unregulated emissions in both cylinder and exhaust were also carefully sdudied. The main research conlusions of this dissertation are as follows:1. A high proportion of the total SOF in PM found in both cylinder and exhaust of the diesel HCCI engine was observed for all operating conditions. The proportions of SOF were measured in-cylinder in the range of 54.6%~90.2% and for exhaust SOF in the range of 42.5%~79.3%, while only 15%~30% for the range of SOF proportion in conventional diesel engine. Thus, it would be possible to further reduce diesel particulate emission using simple after-treatment techniques (e.g. DOC).2. The total mass of 2, 4, 5 aromatic rings in cylinder decreased with increasing engine loads and speed for each operating condition. For exhaust measurements, 3 and 4 aromatic rings were the largest proportion of total PAHs; the brake specific emissions of total PAHs and each rings increased while either intake pressure or increased, except for 2 aromatic rings.3. Acetaldehyde accounted for the largest proportion of the 14 species of carbonyl compounds in exhaust, followed by the acrolein + acetone, and formaldehyde;4. The brake specific emissions of total carbonyl compounds, acetaldehyd and acrolein + acetone were increased with the engine loads for the same EGR rate and intake pressure, while formaldehyde appeared a contrary varying tendancy with engine loads. The brake specific emissions of carbonyl compounds all increased as the intake pressure increased under the same EGR rate and load. For the same intake pressure and load, the brake specific emissions of total carbonyl compounds, formaldehyde, acetaldehyd and acrolein + acetone decreased with the increase of EGR ratio.更多还原