Abstract This paper concerns the effect of unsaturation of hydrocarbons (single, double, and triple bonds) on soot particle characteristics (mass, number, and size) and on the carcinogenicity of soot particles. The soot particles were produced from oxygen-free pyrolysis of five hydrocarbons, namely: propane, propylene, ethane, ethylene, and acetylene. The characteristics of soot particles were measured with the aid of a differential mobility spectrometer (Cambustion-DMS-500) and measurement of soot mass concentration was confirmed using gravimetric filter measurements. The soot particle carcinogenicity was estimated from the emission quantities of total polyaromatic hydrocarbons (PAHs) and the toxicity equivalent factor (TEF) of each PAH. Oxygen-free pyrolysis of the hydrocarbon fuels was conducted in a laminar tube reactor within the temperature range of 1050 –1350oC at a constant nitrogen flow rate of 20 L/min and constant fuel flow rate of 1% (vol) on carbon-1 basis. The experimental results showed that increasing unsaturation of fuels from single to double and to triple bonds increased the mass concentration, particle size, number concentration, and carcinogenicity of soot particle notably at the initial temperature of 1050 oC. Increase in the pyrolysis temperature of the tube reactor from 1050 – 1350oC, increased the mass concentration and sizes of the soot particle while the number concentration and carcinogenicity of the soot particle decreased. There was a positive correlation between the soot particle number and the corresponding soot particle carcinogenicity, while a negative correlation was observed between the soot particle mass and size with soot particle carcinogenicity regardless of the pyrolysis temperature examined. The potential implication of these observations is that, low-temperature combustion (LTC) applications, aimed at reducing emissions of soot and NOx, could produce higher soot particle number concentration of higher carcinogenicity.

中文翻译：

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烃类不饱和度对烟尘颗粒特性及致癌性的影响

摘要 本文关注碳氢化合物的不饱和度（单键、双键和三键）对烟尘颗粒特性（质量、数量和尺寸）和烟尘颗粒致癌性的影响。烟灰颗粒是由五种碳氢化合物（即丙烷、丙烯、乙烷、乙烯和乙炔）的无氧热解产生的。借助微分迁移谱仪 (Cambustion-DMS-500) 测量烟尘颗粒的特性，并使用重力过滤器测量确认烟尘质量浓度的测量。从总多环芳烃 (PAH) 的排放量和每种多环芳烃的毒性当量因子 (TEF) 估计烟尘颗粒致癌性。碳氢燃料的无氧热解在层流管反应器中进行，温度范围为 1050-1350oC，氮气流量恒定为 20 L/min，燃料流量恒定为 1% (vol)，以碳 1 为基础. 实验结果表明，燃料的不饱和度从单键到双键和三键的增加在1050 oC的初始温度下显着增加了烟尘颗粒的质量浓度、粒径、数量浓度和致癌性。管式反应器的热解温度从 1050-1350oC 升高，烟尘颗粒的质量浓度和尺寸增加，而烟尘颗粒的数量浓度和致癌性降低。烟尘颗粒数与相应烟尘颗粒致癌性呈正相关，而不管所检查的热解温度如何，都观察到烟尘颗粒质量和尺寸与烟尘颗粒致癌性之间的负相关。这些观察结果的潜在含义是，旨在减少烟尘和 NOx 排放的低温燃烧 (LTC) 应用可能会产生更高致癌性的更高烟尘粒子数浓度。