Modelling of biodiesel fuel droplet heating and evaporation: Effects of fuel composition
Modelling of biodiesel fuel droplet heating and evaporation: Effects of fuel composition
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DOI：
10.1016/j.fuel.2015.03.051
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发表时间：
2015-08
期刊：
影响因子：
7.4
通讯作者：
Mansour Al Qubeissi;S. Sazhin;C. Crua;J. Turner;M. Heikal
中科院分区：
文献类型：
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作者：
Mansour Al Qubeissi;S. Sazhin;C. Crua;J. Turner;M. Heikal
对现实柴油机条件下生物柴油燃料液滴加热和蒸发的几种模型的预测进行了比较分析。十九种由甲酯组成的生物柴油燃料用于分析。结果表明，该模型基于液滴中物质的扩散率无限快且液体导热系数无限大的假设，与考虑有限扩散率和导热率影响的模型相比，低估了液滴蒸发时间，最高可达约15%。该模型的类似预测结果约为 26%，其中忽略物质的瞬态扩散并假设液体热导率无限大。后者的结果与之前的发现不一致，基于仅对五种生物柴油燃料和不同输入参数的分析，其中表明这些模型预测的蒸发时间之间的偏差不超过约5.5%。与柴油和汽油燃料液滴的情况一样，对于生物柴油液滴，与单组分模型相比，多组分模型预测在液滴蒸发的最后阶段会有更高的液滴表面温度和更长的蒸发时间。这与以下事实有关：在液滴蒸发的最后阶段，较重物质的质量分数增加，而较轻物质的蒸发速度比较轻的物质慢，并且具有较高的沸腾温度，而较轻的物质的质量分数增加。
A comparative analysis of predictions of several models of biodiesel fuel droplet heating and evaporation in realistic Diesel engine-like conditions is presented. Nineteen types of biodiesel fuels composed of methyl esters are used for the analysis. It is shown that the model, based on the assumption that the diffusivity of species in droplets is infinitely fast and the liquid thermal conductivity is infinitely large, under-predicts the droplet evaporation time compared with the model taking into account the effects of finite diffusivity and conductivity, by up to about 15%. A similar under-predictions of the model in which the transient diffusion of species is ignored and the liquid thermal conductivity is assumed to be infinitely large, is shown to be about 26%. The latter result is not consistent with the earlier finding, based on the analysis of only five types of biodiesel fuels and different input parameters, in which it was shown that the deviations between the evaporation times predicted by these models do not exceed about 5.5%. As in the case of Diesel and gasoline fuel droplets, for biodiesel droplets the multi-component models predict higher droplet surface temperatures at the final stages of droplet evaporation and longer evaporation times than for the single-component models. This is related to the fact that at the final stages of droplet evaporation the mass fraction of heavier species, which evaporate more slowly than the lighter species and have higher boiling temperatures, increases at the expense of lighter species.