掺入低浓度乙醛可增强甲烷的自燃性:在化学计量混合物和富混合物中的模拟和 RCM 实验

IF 1.5 4区 化学 Q4 CHEMISTRY, PHYSICAL
Seyed B. Nourani Najafi, Sander Gersen, Hamid Hashemi, Peter Glarborg, Anatoli V. Mokhov, Howard B. Levinsky
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引用次数: 0

摘要

在高压条件下,研究了小部分乙醛(CH3CHO)对甲烷(CH4)点火延迟时间的影响。报告了在快速压缩机(RCM)中,当压缩压力(Pc)为 ∼ 60 巴,压缩后温度(Tc)在 750-900 K 范围内,燃料-空气当量比(j)在 1-4 范围内时,对点火延迟时间的测量结果。结果表明,CH4 中 2%-5% CH3CHO 的混合物在纯甲烷无法点燃的实验条件下点燃。乙醛作为促进剂的效率似乎与醇和醚等其他含氧燃料相当。为了与实验结果进行比较,使用最新的反应机理和文献中有关 CH3CHO 氧化的两种机理计算了点火延迟时间。在大多数条件下,使用当前机理的模拟结果与测量结果一致,误差在 2 倍以内。点火曲线显示了点火前的温度升高和两阶段点火,这与之前在氨中二甲醚的低馏分中观察到的情况类似;模拟捕捉到了这两种现象。在恒定体积下进行的模拟分析表明,CH3CHO 的氧化速度比 CH4 快得多,产生的反应物启动了 CH4 的氧化,并产生热量加速氧化,最终导致点火。CH3CHO 的低温链支化反应对燃料混合物的早期氧化非常重要。模拟结果表明,CH3CHO 对 CH4 有很强的点火促进作用,与纯 CH4 相比,CH3CHO 的小馏分点火延迟时间最多可缩短 100 倍,具体取决于温度。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Autoignition enhancement of methane by admixture of low fraction of acetaldehyde: Simulations and RCM experiments in stoichiometric and rich mixtures

Autoignition enhancement of methane by admixture of low fraction of acetaldehyde: Simulations and RCM experiments in stoichiometric and rich mixtures

The effect of small fractions of acetaldehyde (CH3CHO) on the ignition delay time of methane (CH4) was examined at high pressure. Measurements are reported for the ignition delay time obtained in a rapid compression machine (RCM) at a compression pressure (Pc) of ∼60 bar and temperatures after compression (Tc) in the range 750–900 K for fuel-air equivalence ratios ϕ in the range 1–4. The results show that mixtures of 2%–5% CH3CHO in CH4 ignite under conditions at which pure methane does not ignite experimentally. The efficiency of acetaldehyde as a promoter seems to be comparable to that of other oxygenated fuels like alcohols and ethers. For comparison with the experimental results, ignition delay times are computed using an updated reaction mechanism and two mechanisms from the literature for CH3CHO oxidation. For most conditions, the simulations using the current mechanism agree with the measurements to within a factor of two. The ignition profile shows a pre-ignition temperature rise and two-stage ignition similar to that previously observed in low fractions of dimethyl ether in ammonia; both phenomena are captured by the simulations. Analysis of simulations at constant volume indicates that CH3CHO is oxidized much more rapidly than CH4, producing reactive species that initiate the oxidation of CH4 and generates heat that accelerates oxidation toward ignition. The low-temperature chain-branching reactions of CH3CHO are important in the early oxidation of the fuel mixture. Additional simulations were performed for equivalence ratios of ϕ = 1 and 4, at a compression pressure (Pc) of 100 bar and Tc = 750–1000 K. The simulations indicate that CH3CHO has a strong ignition-enhancing effect on CH4, with small fractions reducing the ignition delay time by up to a factor of 100, depending on the temperature, as compared to pure CH4.

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来源期刊
CiteScore
3.30
自引率
6.70%
发文量
74
审稿时长
3 months
期刊介绍: As the leading archival journal devoted exclusively to chemical kinetics, the International Journal of Chemical Kinetics publishes original research in gas phase, condensed phase, and polymer reaction kinetics, as well as biochemical and surface kinetics. The Journal seeks to be the primary archive for careful experimental measurements of reaction kinetics, in both simple and complex systems. The Journal also presents new developments in applied theoretical kinetics and publishes large kinetic models, and the algorithms and estimates used in these models. These include methods for handling the large reaction networks important in biochemistry, catalysis, and free radical chemistry. In addition, the Journal explores such topics as the quantitative relationships between molecular structure and chemical reactivity, organic/inorganic chemistry and reaction mechanisms, and the reactive chemistry at interfaces.
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