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Dynamic evolution of impaction and sticking behaviors of fly ash particle in pulverized coal combustion
Proceedings of the Combustion Institute ( IF 3.4 ) Pub Date : 2018-06-28 , DOI: 10.1016/j.proci.2018.06.035
Qian Huang , Shuiqing Li , Yachan Shao , Yingqi Zhao , Qiang Yao

This paper aims to reveal the mechanisms governing the impaction and sticking dynamics of fly ash particles in pulverized coal combustion. The modeling work is of relevance to experiments in a 25 kW self-sustained down-fired furnace, which provides a sequence of real deposit shapes as varied boundary conditions for CFD simulations. Although the formed ash deposit has a comparable length scale with the probe, it has little effect on the global impaction efficiency of newly-coming particles. However, as the deposit builds up, incident particles impact the deposit and probe at generally larger impact angles and smaller normal velocities despite the almost invariant global impaction efficiency. It results in an enhanced local sticking probability in the center region of the probe, but a decreased one in the lateral regions. The incident kinetic energy of newly sticking particles to the deposit exhibits a converse correlation with their impact angle. The relationship of the averaged local sticking probability as a function of the azimuthal angle of probe is illustrated. Finally, the effect of Reynolds number on global particle impaction efficiency is examined. A universal formula is proposed, which is of importance to bridge lab-scale experiments and practical applications.



中文翻译:

粉煤燃烧中粉煤灰颗粒撞击和黏附行为的动态演变

本文旨在揭示控制粉煤燃烧中粉煤灰颗粒的撞击和黏附动力学的机理。建模工作与在25 kW自持式向下燃烧炉中进行的实验有关,该炉提供了一系列实际沉积物形状,作为CFD模拟的各种边界条件。尽管形成的灰烬沉积物的长度尺度与探针相当,但对新出现的颗粒的整体撞击效率影响很小。但是,随着沉积物的堆积,尽管总体撞击效率几乎不变,但入射粒子仍会以较大的撞击角和较小的法向速度撞击沉积物并进行探测。这会导致在探针中心区域的局部粘连概率增加,而在横向区域中的粘连概率降低。新附着在沉积物上的颗粒的入射动能与其冲击角呈反比关系。示出了平均局部粘附概率与探针的方位角的函数的关系。最后,研究了雷诺数对整体粒子碰撞效率的影响。提出了一个通用公式,该公式对于桥接实验室规模的实验和实际应用非常重要。

更新日期:2018-06-28
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