Abstract In this work, the charge characteristics of sub-10 nm soot particles were studied in burner-stabilized-stagnation premixed ethylene flames, at an equivalent ratio of 2.0 and over the calculated maximum flame temperature (Tmax) range of 1665–1933 K, using micro-orifice probe sampling in tandem with neutralizer, half-mini differential mobility analyzer (Half-mini DMA) and electrometer. To obtain the charge fraction, the charged and total particle size distributions (PSDs) were measured with the neutralizer off and on, separately. Our results showed that both negatively charged particles (NCP) and positively charged particles (PCP) grew to bigger particles with the increase of height above burner (Hp). However, compared to PCP, NCP were relatively smaller in size, but higher in concentration, possibly because negative ions such as electrons diffused faster to coagulate with soot. Moreover, charge fraction decreased along Hp and newly nucleated soot particles were all neutral at higher Hp, which could be attributed to the higher temperature near the flame front, where the concentrations of ions were higher. Another interesting finding was the increase in charge fraction by two orders of magnitude (from 0.1% to 10%) as Tmax increased from 1665 K to 1933 K. All of these suggested the existence of particle-ions interaction close to the flame front, especially at high temperatures.

中文翻译：

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预混乙烯火焰中亚 10 nm 烟尘颗粒的电荷特性

摘要 在这项工作中，研究了亚 10 nm 烟尘颗粒在燃烧器稳定停滞预混乙烯火焰中的电荷特性，当量比为 2.0 和计算的最高火焰温度 (Tmax) 范围为 1665-1933 K，使用与中和器、半微型差分迁移率分析仪（半微型 DMA）和静电计串联的微孔探针采样。为了获得电荷分数，分别在中和器关闭和打开的情况下测量带电和总粒度分布 (PSD)。我们的结果表明，随着燃烧器上方高度 (Hp) 的增加，带负电的粒子 (NCP) 和带正电的粒子 (PCP) 都成长为更大的粒子。然而，与PCP相比，NCP的体积相对较小，但浓度较高，可能是因为电子等负离子扩散得更快，与烟灰凝结。此外，电荷分数沿 Hp 降低，并且新成核的烟尘颗粒在较高的 Hp 下都是中性的，这可能是由于火焰前缘附近的温度较高，离子浓度较高。另一个有趣的发现是，随着 Tmax 从 1665 K 增加到 1933 K，电荷分数增加了两个数量级（从 0.1% 到 10%）。所有这些都表明在火焰前沿附近存在粒子-离子相互作用，尤其是在高温下。离子浓度较高的地方。另一个有趣的发现是，随着 Tmax 从 1665 K 增加到 1933 K，电荷分数增加了两个数量级（从 0.1% 到 10%）。所有这些都表明在火焰前沿附近存在粒子-离子相互作用，尤其是在高温下。离子浓度较高的地方。另一个有趣的发现是，随着 Tmax 从 1665 K 增加到 1933 K，电荷分数增加了两个数量级（从 0.1% 到 10%）。所有这些都表明在火焰前沿附近存在粒子-离子相互作用，尤其是在高温下。