Modelling of laminar diffusion flames with biodiesel blends and soot formation
Modelling of laminar diffusion flames with biodiesel blends and soot formation
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DOI：
10.1016/j.fuel.2021.122897
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发表时间：
2022
期刊：
影响因子：
7.4
通讯作者：
Anxiong Liu;Zhan Gao;S. Rigopoulos;K. Luo;Lei Zhu
中科院分区：
文献类型：
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作者：
Anxiong Liu;Zhan Gao;S. Rigopoulos;K. Luo;Lei Zhu
由于化学反应和烟灰形成途径的复杂性，对生物柴油燃料的烟灰形成和氧化进行建模是一项挑战。在本文中，离散群体平衡方法和基于 PAH-HACA 的详细烟灰模型与内部 CFD 代码相结合，模拟含氧生物柴油燃料不同成分混合物的层流扩散火焰，并用于预测燃烧性能和烟灰形成。该模拟旨在重现一个目标实验，通过将 DBE 的摩尔分数从 0% 增加到 40%，研究添加二丁基醚 (DBE) 对生物柴油替代品（癸酸甲酯，MD）的影响。模拟中采用了由三个子机制分支开发的组合和简化的 MD-DBE-PAH 机制。模拟结果表明，随着 DBE 百分比增加到 40%，温度升高。正确预测了烟尘发生区的燕尾形状和烟尘产生量。关于烟灰抑制效果，模型在测量中基本捕捉到了随着DBE添加量从0%增加到40%，烟灰形成减少的趋势。由于添加了 DBE，有助于形成芳香环的 PAH 和 C3 物质的浓度略有降低，DBE 是抑制烟灰的主要原因。然而，总体而言，在不同MD/DBE比率的层流火焰中，数值解的差异比实验中观察到的差异小得多，因为组合的MD-DBE-PAH机制仅呈现出烟灰前体物质浓度的微小差异。
Modelling of soot formation and oxidation of biodiesel fuels is a challenge, due to the complexity of the chemical reactions and soot formation pathways. In this paper, the discretised population balance approach and a PAH-HACA based detailed soot model have been coupled with an in-house CFD code to simulate a laminar diffusion flame with blends of different components of oxygenated biodiesel fuel, and employed to predict combustion performance and soot formation. The simulation aims to reproduce a target experiment which investigated the effects of dibutyl ether (DBE) addition to the biodiesel surrogate (methyl decanoate, MD) by increasing the mole fraction of DBE from 0 to 40%. A combined and reduced MD–DBE–PAH mechanism developed from three sub-mechanism branches has been employed in the simulation. The simulation results show that temperature rises as the DBE percentage increases to 40%. The swallow-tail shape of the soot occurrence zone and the quantity of soot production are correctly predicted. Regarding the effect of soot suppression, the model has basically captured the reducing tendency of soot formation in the measurements as the DBE addition increases from 0% to 40%. Concentrations of PAHs and C3 species contributing to the formation of aromatic rings are slightly reduced due to the addition of DBE, which is a leading cause of soot suppression. However, on the whole, the numerical solution featured much smaller differences than those observed in the experiment among laminar flames with different MD/DBE ratios, because the combined MD–DBE–PAH mechanism only present a slight difference of concentrations of soot precursor species.