Coal direct liquefied diesel (DDCL) is a new alternative fuel with high cleanliness and quality. Its hydrocarbon composition and physicochemical properties are quite different from those of petrochemical diesel. In order to study the difference in evaporative burning characteristics between DDCL and diesel during the sequential burning of multiple droplets, three fuel droplets are suspended on fibers in order by a micro-injector. The first droplet was ignited by an electrode igniter, and then the sequential burning process of three droplets was captured by a high-speed camera. An automatic processing program is written based on Matlab software to calculate the equivalent diameter of each fuel droplet. The result shows that the burning process of the DDCL droplet can be divided into three stages: initial thermal expansion, steady burning, and late micro-explosion burning. DDCL is much easier to form the burning mixture and has better flammability than diesel. The droplet spacing and fuel type have significant effects on ignition delay. The square of the normalized diameter of droplets decreases linearly with time during the steady burning period, which follows the D² law. The reduction rates of normalized squared diameter for DDCL droplets are higher than that for diesel. The pyrolysis of macromolecular components at high temperature produces many small molecules and low boiling point components, which induce the micro-explosions in the late burning stage. The micro-explosion intensity of DDCL droplets is obviously lower than that of diesel.

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煤直接液化柴油的三滴连续燃烧特性研究

煤炭直接液化柴油（DDCL）是一种清洁度高，质量高的新型替代燃料。它的碳氢化合物组成和理化特性与石化柴油完全不同。为了研究在多个液滴的顺序燃烧期间DDCL和柴油之间的蒸发燃烧特性的差异，将三个燃料液滴通过微型喷射器依次悬浮在纤维上。第一个液滴由电极点火器点燃，然后通过高速相机捕获三个液滴的顺序燃烧过程。基于Matlab软件编写了一个自动处理程序，以计算每个燃油滴的等效直径。结果表明，DDCL液滴的燃烧过程可分为三个阶段：初始热膨胀，稳定燃烧，和后期微爆炸燃烧。DDCL比柴油更容易形成燃烧混合物，并且具有更好的可燃性。液滴间距和燃料类型对点火延迟有重要影响。在稳定燃烧期间，液滴的归一化直径的平方随时间线性减小，随D ²法。DDCL液滴的归一化平方直径的减小率高于柴油。高温下大分子组分的热解产生许多小分子和低沸点组分，从而在燃烧后期引起微爆炸。DDCL液滴的微爆炸强度明显低于柴油。