Experimental and modeling investigation of the effect of the unsaturation degree on the gas-phase oxidation of fatty acid methyl esters found in biodiesel fuels
Experimental and modeling investigation of the effect of the unsaturation degree on the gas-phase oxidation of fatty acid methyl esters found in biodiesel fuels
复制标题
DOI：
10.1016/j.combustflame.2015.11.032
复制
发表时间：
2016-02
影响因子：
4.4
通讯作者：
Anne Rodriguez;O. Herbinet;F. Battin‐Leclerc;A. Frassoldati;T. Faravelli;E. Ranzi
中科院分区：
文献类型：
--
作者：
Anne Rodriguez;O. Herbinet;F. Battin‐Leclerc;A. Frassoldati;T. Faravelli;E. Ranzi
使用喷射搅拌反应器对生物柴油中存在的三种C19脂肪酸甲酯的氧化进行了实验研究，以强调双键对反应性和产物分布的影响。燃料候选物分别是不含双键、含一个双键和含两个双键的硬脂酸甲酯、油酸甲酯和亚油酸甲酯。实验在宽的温度范围（500-1050 K）内、在1.067巴的压力下、在2秒的停留时间下进行。用苯稀释甲酯以尽可能避免它们的缩合。甲酯、苯和氧气的入口摩尔分数分别为4 × 10−4、5 × 10− 3和4.5 × 10−2（在氦气中稀释）。然而，如先前对于烷烃所证明的，苯的存在在850 K以下并不显著影响混合物的反应性。许多反应中间产物已经被定量，包括可以通过不饱和反应物的Waddington反应形成的物质。本实验是第一个允许在喷射搅拌反应器中实际测量大酯固有反应性的实验。它们进一步有助于生物柴油燃料热解和氧化的POLIMI集总动力学方案的广泛验证。为了更好地解释具有双键的物种的氧化，增加了两类反应：Waddington机制和通过环状过渡态的协同分解反应。新模型包含18，217个反应，涉及461个物种。总的来说，得到了正确的协议的反应性的三种燃料。该模型很好地再现了许多反应产物的摩尔分数分布。在低温（650 K）下进行的动力学分析证实了显着的抑制效果的H-原子抽象形成非传播烯丙基型自由基在这个温度区域。它还表明，这些反应的抑制效果从油酸甲酯到亚油酸甲酯增加，这解释了在反应性中观察到的大的差异。
The oxidation of three C19fatty acid methyl esters present in biodiesel fuel was experimentally investigated using a jet-stirred reactor in order to highlight the effect of double bonds on the reactivity and product distribution. Fuel candidates were methyl-stearate, methyl oleate and methyl linoleate with no, one and two double bonds, respectively. Experiments were carried out over a wide temperature range (500–1050 K), at a pressure of 1.067 bar, at a residence time of 2 s. Methyl esters were diluted with benzene to avoid their condensation as much as possible. Inlet mole fractions of methyl ester, benzene and oxygen were 4 × 10−4, 5 × 10−3and 4.5 × 10−2, respectively (with dilution in helium). However, as previously demonstrated for alkanes, the presence of benzene does not notably influence the mixture reactivity below 850 K. Many reaction intermediate products have been quantified, including species which can be formed through Waddington reaction for unsaturated reactants. The present experiments are the first ones allowing the actual measurement of large ester intrinsic reactivity in a jet-stirred reactor. They further contribute to an extensive validation of the POLIMI lumped kinetic scheme of pyrolysis and oxidation of biodiesel fuels. Two reaction classes have been added to better account for the oxidation of species with double bonds: the Waddington mechanism and the concerted decomposition reactions through cyclic transition states. The new model contains 18,217 reactions involving 461 species. Overall, a correct agreement was obtained for the reactivity of the three fuels. The model well reproduces mole fraction profiles of many reaction products. The kinetic analysis performed at low-temperature (650 K) confirmed the significant inhibitive effect of H-atom abstractions forming non-propagating allyl type radicals in this temperature region. It also showed that the inhibitive effect of these reactions increases from methyl oleate to methyl linoleate, which explains the large difference observed in the reactivity.