甲烷-正庚烷双燃料二阶段着火的动力学特性

Kinetic characteristics on two-stage ignition of methane-n-heptane dual fuel

摘要:

基于CHEMKIN PRO软件,选取NUI 2016机理对甲烷-正庚烷双燃料进行研究. 探究了甲烷-正庚烷双燃料在中低温条件下的二阶段着火特性,开展了相应的化学动力学分析. 结果表明:二阶段着火现象在初始温度低于750 K时出现,二阶段着火过程均表现出一定的NTC（负温度系数）现象；随着正庚烷掺混比例的增加,双燃料的二阶段着火延迟时间均减小,在正庚烷掺混比例小于75%时影响最为显著；通过相关化学动力学分析发现,甲烷主要在第二阶段被消耗,正庚烷在第一阶段进行氧化分解,在第二阶段着火过程中被完全氧化；通过反应路径分析发现,第一阶段反应产生的自由基和中间产物提高了系统活性,促进了双燃料的着火过程.

Abstract:

Based on the CHEMKIN PRO software, this paper selects the NUI 2016 mechanism to study methane-n-heptane dual fuel. The two-stage ignition characteristics of methane-n-heptane dual fuel under medium and low temperature conditions were investigated, and the corresponding chemical kinetic analysis was carried out. The results show that the two-stage ignition behavior occurs when the initial temperature is lower than 750 K, and the two-stage ignition process shows a certain NTC (negative temperature coefficient) behavior; with the increase of n-heptane content, the two-stage ignition delay time is reduced, and the effect is most significant when the n-heptane content below about 75%. The related chemical kinetic analysis shows that the methane is mainly consumed in the second stage, the n-heptane is oxidatively decomposed in the first stage and during the second stage it is completely oxidized. By the reaction path analysis, it is found that the radicals and intermediates produced by the first stage reaction increase the activity of the system and promote the ignition process of the dual fuel.