己酸甲酯和正丁醇混合燃料着火延迟试验和模拟

Experimental and Modeling on Ignition Delay of Binary Fuel Blends of Methyl Hexanoate and n-Butanol

通过一台快速压缩机开展了己酸甲酯和正丁醇混合燃料着火延迟的试验.混合气初始温度为353,K,当量比为1.0,采用79%的Ar/N2混合气进行稀释,上止点压力分别为1.1、1.5和2.0,MPa,正丁醇在混合燃料中的比例分别为0、40%和60%,压缩上止点温度为660~830,K.利用CHEMKIN软件在较宽温度范围内对混合燃料着火延迟进行了模拟比较.结果表明:己酸甲酯/正丁醇的着火延迟随温度变化表现出3阶段燃烧特性,具有明显的负温度系数现象.混合燃料的着火延迟随压缩压力的增大而减小,随正丁醇预混比的增大而增加,正丁醇可减弱混合燃料燃烧爆震倾向.低温燃烧时,混合燃料中的己酸甲酯和正丁醇都呈现两阶段反应特征.高温燃烧时,混合燃料中的己酸甲酯和正丁醇都呈现出单阶段反应现象.正丁醇的加入对己酸甲酯的低温反应路径有较为明显的影响,对其高温反应路径影响不大.

Ignition delay of binary fuel blends of methyl hexanoate and n-butanol mixed with oxygennitrogen were measured in a rapid compression machine at a compressed pressure of 1.1,1.5 and 2.0,MPa,initial temperature 353,K. For fuel/oxidizer mixture,compressed temperatures vary in the range of 660—830,K with equivalence ratio of 1.0. Kinetics model was built to predict the ignition delay and simulate the combustion process. Main reaction pathways involved in the binary fuel oxidation were delineated. Over the conditions researched in this study,ignition delay of binary fuel shows obvious three regimes of oxidation,namely cool flame,negative temperature coefficient,and high temperature oxidation. Ignition delay of binary fuel decreases with the increase of compression pressure,and it increases with the increase of n-butanol proportion. Knocking degree of binary fuel combustion is weakened by increasing n-butanol proportion. Both methyl hexanoate and n-butanol shows two-stage heat release at low temperature and single-stage heat release at high temperature. n-Butanol has an obvious effect on the reaction pathways of methyl hexanoate in high temperature and slight effect in low temperature oxidations.