Intermittent Combustion Mechanism of Ester-Series Oxygenated Compounds

研究了酯类、碳酸盐类、乙酸酯类、醇类等含氧化合物的基本热性能和间歇燃烧特性。结果总结如下：各种氧合物的热值、理论空气温度、绝热火焰温度和平衡NO浓度等基本热性能与氧合物的种类无关，只与氧含量有关，并随氧含量的增加而线性降低。含氧物每单位热值的二氧化碳量也仅由氧含量决定，其含量高于含氧30%以上的普通HC燃料。在间歇性压缩点火发动机中使用氧合物已被证明可以显著改善碳颗粒，也可以提高热效率和氮氧化物。即使在化学计量混合物中，碳颗粒在含氧量38%以上也完全消失，这表明在EGR和后处理系统相结合的压缩点火发动机中，可以实现超低排放和高功率的燃烧。氧混合燃料的热效率的提高是由于燃烧时间的缩短，这是由氧混合燃料液滴在高温下燃烧过程中的微爆炸现象估计的。

This research investigated the fundamental thermal properties and intermittent combustion characteristics for various oxygenated compounds including esters, carbonates, acetates, alcohols and so on.The results are summarized as follows ;Basic thermal properties of various oxygenates including heat values, theoretical air, adiabatic flame temperatures and aquilibrium NO concentrations did not depend on the kinds of oxygenates but only on their oxygen contents, decreasing linearly with an increase in oxygen contents. CO2 amounts per unity of heat values for the oxygenates were also determined only by oxygen contents, showing higher amounts than that of usual HC fuels above oxygen contents of 30%.The use of oxygenates in intermittent compression ignition engines was proved to improve carbon particulates significantly, also to improve thermal efficiency and NOx. The carbon particulates disappeared perfectly above oxygen contents of 38% even at stoichometric mixtures, suggesting that combustion with ultra low emission and high power could be achieved in compression ignition engines with combination of EGR and aftertreatment systems.The improvement of thermal efficiency with oxygenate blend fuels resulted from shorter combustion duration which were estimated by micro-explosion phenomena of an oxygenate blend droplet during combustion processes in high temperatures.