生物柴油滞燃特性的化学动力学机理分析

摘要

采用正庚烷和癸酸甲酯化学动力学组合机理，利用 CHEMKIN-PRO 均质零维反应器模型对生物柴油滞燃特性进行模拟计算与分析。结果表明：随着初始温度和压力的上升，着火延迟时间迅速减小，在750～900 K之间出现了明显的负温度系数现象；生物柴油体积分数的增加，使得 OH 自由基的浓度峰值上升并且提前出现，诱导火焰提前产生，导致着火延迟时间缩短；脂肪族链上C＝C 双键使得附近C-H键能变弱，促使过氧基的异构化反应减少，抑制了低温链分支反应；C＝C双键数量越多及C＝C双键越靠近脂肪族链中心位置，对低温活性的抑制作用越大，着火延迟时间越长。%Ignition delay time of biodiesel was calculated by using closed homogeneous model of CHEMKIN -PRO, based on detailed chemical kinetic mechanism of n-heptane and methyl decanoate .The results showed that the ignition delay time decreased rapidly with the increase of initial temperature and pressure , and a negative temperature coefficient region was found at 750~900K.The peak concentration of OH radical occurred earlier , thus induced a advanced flame , resul-ting in a shortened ignition delay time with increasing biodiesel blending ratios .The C=C double bond in the aliphatic main chain caused that the H atoms adjacent to the C=C double bond was easily abstracted , but these allylic radical sites were shown to be weak bonding sites for molecular oxygen that do not support subsequent isomerization reactions which lead to low temperature reactivity .In addition , the inhibition effect of the double bond on the low-temperature oxidation reactivity of fatty acid esters became more pronounced as the double bond moved toward the central position of the aliphatic main chain .