Chemical interaction of dual-fuel mixtures in low-temperature oxidation, comparing n-pentane/dimethyl ether and n-pentane/ethanol
Chemical interaction of dual-fuel mixtures in low-temperature oxidation, comparing n-pentane/dimethyl ether and n-pentane/ethanol
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DOI：
10.1016/j.combustflame.2018.03.003
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发表时间：
2018-07
影响因子：
4.4
通讯作者：
Hanfeng Jin;Julia Pieper;C. Hemken;Eike Bräuer;L. Ruwe;K. Kohse-Höinghaus
中科院分区：
文献类型：
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作者：
Hanfeng Jin;Julia Pieper;C. Hemken;Eike Bräuer;L. Ruwe;K. Kohse-Höinghaus
为了研究双燃料组合在低温氧化中的潜在协同效应，我们研究了正戊烷掺入二甲醚(DME)或乙醇(EtOH)的典型碳氢化合物(C5H12)/含氧(C2H6O)燃料混合物。在流动反应器中，当量比为ϕ= 0.7时，压力为p= 970mbar，温度范围为450K-930mbar，用电子电离分子束质谱(EI-MBMS)进行了物种测量。研究了三种纯燃料和C2H6O含量分别为25%和50%的正戊烷混合燃料的不同掺混比。分析了元素组成为CnH_2n+xO_y(n= 1-5，x= 0-(n+ 2)，y= 0-3)的大量物种的摩尔分数和信号，以表征混合物相对于单个组分的行为。不出所料，乙醇掺杂会降低正戊烷的整体反应活性，而二甲醚的加入会促进正戊烷的整体反应活性。有趣的是，本实验揭示了正戊烷和二甲醚之间的协同作用，显示出对混合物的负温度系数(NTC)的影响比对单个组分的影响更大。对这种行为的原因进行了研究，发现几种含氧中间体参与了增强OH自由基的产生。相反，乙醇通过加成正戊烷而被激活，同样涉及关键的OH自由基反应。虽然这里的主要焦点是实验结果，但我们试图在第一近似值中，通过用最近的动力学模型模拟来补充实验观察结果。在燃料消耗和中间物种产量这两个方面的比较中，观察到了有趣的差异。乙醇的缓蚀作用没有得到充分的预测，二甲醚的协同作用也没有得到令人满意的捕捉。对现有模型的实验结果的探索性分析表明，对低温区域的反应化学有更深入的了解将是有用的，并可能有助于改进对此类燃料混合物的低温氧化行为的预测。
With the aim to study potential cooperative effects in the low-temperature oxidation of dual-fuel combinations, we have investigated prototypical hydrocarbon (C5H12) / oxygenated (C2H6O) fuel mixtures by dopingn-pentane with either dimethyl ether (DME) or ethanol (EtOH). Species measurements were performed in a flow reactor at an equivalence ratio ofϕ= 0.7, at a pressure ofp= 970 mbar, and in the temperature range of 450–930 K using electron ionization molecular-beam mass spectrometry (EI-MBMS). Series of different blending ratios were studied including the three pure fuels and mixtures ofn-pentane containing 25% and 50% of C2H6O. Mole fractions and signals of a significant number of species with elemental composition CnH2n+xOy(n= 1–5,x= 0–(n+ 2),y= 0–3) were analyzed to characterize the behavior of the mixtures in comparison to that of the individual components. Not unexpectedly, the overall reactivity ofn-pentane is decreased when doping with ethanol, while it is promoted by the addition of DME. Interestingly, the present experiments reveal synergistic interactions betweenn-pentane and DME, showing a stronger effect on the negative temperature coefficient (NTC) for the mixture than for each of the individual components. Reasons for this behavior were investigated and show several oxygenated intermediates to be involved in enhanced OH radical production. Conversely, ethanol is activated by the addition ofn-pentane, again involving key OH radical reactions. Although the main focus here is on the experimental results, we have attempted, in a first approximation, to complement the experimental observations by simulations with recent kinetic models. Interesting differences were observed in this comparison for both, fuel consumption and intermediate species production. The inhibition effect of ethanol is not predicted fully, and the synergistic effect of DME is not captured satisfactorily. The exploratory analysis of the experimental results with current models suggests that deeper knowledge of the reaction chemistry in the low-temperature regime would be useful and might contribute to improved prediction of the low-temperature oxidation behavior for such fuel mixtures.