Intermittent Combustion Mechanism of Ester-Series Oxygenated Compounds

对含氧化合物的基本热物性和间歇燃烧特性进行了研究，结果表明：各种含氧物的基本热物性，包括热值、理论空气、绝热火焰温度和平衡NO浓度与含氧物的种类无关，只与含氧物的含氧量有关，随含氧量的增加呈线性下降。含氧物单位热值的CO2含量也仅由含氧量决定，氧含量高于30%的普通碳氢燃料的含氧量高于普通碳氢燃料。在间歇式压燃式发动机上使用含氧物可以显著改善碳颗粒，并改善热效率和NOx。即使在化学均质混合气中，碳颗粒也完全消失在氧含量38%以上，这表明采用EGR和后处理系统相结合的压燃式发动机可以实现超低排放和高功率燃烧。含氧混合燃料热效率的提高源于燃烧持续时间的缩短，这是通过高温燃烧过程中含氧混合液滴的微爆炸现象来估计的。

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.