癸酸甲酯与正丁醇在低速柴油机中均质压燃燃烧与排放

通过向生物柴油替代燃料癸酸甲酯(MD)中掺入一定比例的正丁醇(NBA)，达到降低氮氧化物（NOx）排放的目的。针对二冲程低速船用柴油机，建立了癸酸甲酯和正丁醇的混合燃料燃烧反应机理，并将Zeldovich氮氧化物反应机理作为子机理添加到燃烧反应机理中。构建出一个包含癸酸甲酯，正丁醇和详细的氮氧化物反应的完整燃烧反应机理。在燃料总摩尔分数一定的条件下，固定发动机转速与空气过量系数，将癸酸甲酯与正丁醇按不同比例进行混合，研究癸酸甲酯与正丁醇混合燃料在二冲程低速船用柴油机充量均质压燃（HCCI）模式下的燃烧与氮氧化物排放特性。结果显示，癸酸甲酯与正丁醇混合燃料HCCI燃烧产生的氮氧化物随正丁醇掺混比例的增加而减少。研究表明，在燃料总摩尔分数保持不变时，随着正丁醇混合比例的增加，燃料总热值减少，排气温度和缸内最高燃烧温度降低，对氮氧化物的生成有抑制作用，氮氧化物反应速率降低，排放量下降。同时，由于正丁醇掺混比例的增加导致混合燃料的C/H比下降，可以有效地降低燃烧过程中CO2的排放。在保证发动机燃烧效率的条件下，癸酸甲酯和正丁醇的混合比例为1:1时，混合燃料在二冲程低速船用柴油机中HCCI燃烧的NO与NO2排放量最低。

Homogeneous Charge Compression Ignition Combustion and Emissions of Methyl Decanoate and n-Butanol in Low-Speed Diesel Engine

NOx emission can be reduced by adding a certain proportion of n-butanol (NBA) into methyl decanoate (MD). A mixed fuel combustion reaction mechanism including methyl decanoate and n-butanol was established for two-stroke low-speed marine diesel engine, the NOx reaction mechanism of Zeldovich was added to the combustion reaction mechanism as sub-mechanism. A complete combustion reaction mechanism including methyl decanoate, n-butanol and detailed NOx reaction was constructed in the research. The total mole fraction of the mixtures was remained unchange, the engine speed and excess air coefficient was fixed. The combustion and NOx emission characteristics of the mixture of methyl decanoate and n-butanol on homogeneous charge compression ignition (HCCI) were studied with different proportions. The results show that the emissions of NOx decrease with the increase of n-butanol blending ratio in HCCI combustion. The study shows that different mixing ratios of methyl decanoate and n-butanol were used at the same total mole fraction. With the increase of n-butanol ratio, the total heating value of the mixed fuel decreases, the exhaust temperature and in-cylinder peak temperature decrease, it can inhibit the formation of NOx. The reaction rate of NOx decreases significantly with the increase of n-butanol mixing ratio. NOx emissions decrease due to the decrease of reaction rate. At the same time, the C/H ratio of the mixed fuel decreases due to the increase of n-butanol blending ratio, CO2 emissions have a significant decline. Under the premise of ensuring the engine combustion efficiency, when the mixing ratio of methyl decanoate and n-butanol is 1: 1, the two-stroke low-speed marine diesel engine has the lowest emissions of NO and NO2 in HCCI combustion.