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Quantum-chemical analysis of the processes at the surfaces of Diesel fuel droplets

机译：柴油机油滴表面过程的量子化学分析

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摘要

The quantum-chemical methods used for describing the processes at the surface of Diesel fuel droplets are summarised. Some results relevant to practical engineering application in Diesel engines, obtained previously, are summarised. Assuming that the droplets are so small that their interaction with individual molecules can be described using the methods of the kinetic gas theory (they can be considered as clustersanodrops), it was shown that the evaporation rate depends on partial pressures, temperature, and the sizes and masses of molecules and clustersanodrops. The results of the analysis of the collision processes between n-dodecane (approximation of Diesel fuel) molecules and clustersanodrops, based on the Dynamic Reaction Coordinate (DRC) method, are described. It is concluded that the probability of the attacking molecule sticking to a droplet is maximal if the molecular plane is parallel or almost parallel to the droplet surface. If the kinetic energy of the attacking molecules is high (greater than that corresponding to the boiling temperature) then it is expected that it will scatter and be removed from the clusteranodrop surface. The mechanisms of evaporation of microdrops and nanodrops are shown to involve rather different processes. In the case of microdrops, individual C-12 molecules are evaporated from their surfaces, while in the case of nanodrops they can be disintegrated into clusters and individual molecules. The decrease in the likelihood of evaporation/condensation with temperature, predicted by the quantum-chemical (QC) approach, agrees with the prediction of the classical theory based on the MD simulations of n-dodecane molecules. The results of the estimation of the evaporation/condensation coefficient of n-dodecane molecules using the transition state theory (TST), based on the QC/DFT approach and taking into account the conformerisation of n-dodecane molecules, are summarised. It is shown that taking into account the QC effects leads to marginal modifications of the predicted evaporation/condensation coefficient, particularly at temperatures which are not close to the critical temperature. (C) 2015 Elsevier Ltd. All rights reserved.
机译：总结了用于描述柴油机燃料液滴表面过程的量子化学方法。总结了先前获得的与柴油机实际工程应用相关的一些结果。假设液滴是如此之小，以至于可以使用动气理论的方法描述它们与单个分子的相互作用（可以将它们视为簇/纳米液滴），则表明蒸发速率取决于分压，温度和分子和簇/纳米滴的大小和质量。描述了基于动态反应坐标（DRC）方法的正十二烷（柴油燃料近似值）分子与团簇/纳米滴之间的碰撞过程分析结果。结论是，如果分子平面平行于或几乎平行于液滴表面，则攻击分子粘附在液滴上的可能性最大。如果攻击分子的动能很高（大于对应于沸腾温度的动能），那么预计它将散乱并从团簇/纳米滴表面除去。显示了微滴和纳米滴的蒸发机制涉及相当不同的过程。在微滴的情况下，单个C-12分子从其表面蒸发，而在纳米滴的情况下，它们可以分解成簇和单个分子。通过量子化学（QC）方法预测的蒸发/冷凝可能性随温度的降低与基于正十二烷分子的MD模拟的经典理论的预测相符。总结了基于QC / DFT方法并考虑了正十二烷分子构象关系的过渡态理论（TST）估算正十二烷分子蒸发/冷凝系数的结果。结果表明，考虑到QC效应会导致预测的蒸发/冷凝系数的边际变化，特别是在不接近临界温度的温度下。 （C）2015 Elsevier Ltd.保留所有权利。

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  • 来源
    《Fuel》 |2016年第1期|405-412|共8页
  • 作者

    Sazhin S. S.; Gunko V. M.; Nasiri R.;

  • 作者单位

    Univ Brighton, Sch Comp Engn & Math, Ctr Automot Engn, Sir Harry Ricardo Labs, Brighton BN2 4GJ, E Sussex, England;

    Univ Brighton, Sch Comp Engn & Math, Ctr Automot Engn, Sir Harry Ricardo Labs, Brighton BN2 4GJ, E Sussex, England|Chuiko Inst Surface Chem, UA-03164 Kiev, Ukraine;

    Univ Brighton, Sch Comp Engn & Math, Ctr Automot Engn, Sir Harry Ricardo Labs, Brighton BN2 4GJ, E Sussex, England;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Diesel fuel; Droplet evaporation; Gibbs free energy; Evaporation rate; Evaporation/condensation coefficient; Quantum chemical modelling;

    机译：柴油;小滴蒸发;吉布斯自由能;蒸发速率;蒸发/冷凝系数;量子化学模型;

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