Investigating the dependence of light-absorption properties of combustion carbonaceous aerosols on combustion conditions
Investigating the dependence of light-absorption properties of combustion carbonaceous aerosols on combustion conditions
复制标题
DOI：
10.1080/02786826.2019.1566593
复制
发表时间：
2019-04-03
影响因子：
5.2
通讯作者：
Saleh, Rawad
中科院分区：
文献类型：
--
作者：
Cheng, Zezhen;Atwi, Khairallah;Saleh, Rawad
通过控制燃烧实验研究了燃烧含碳气溶胶排放物的质量吸收截面（MAC）和吸收埃-恩-斯特伦指数（AAE）随燃烧条件的变化规律。以苯和甲苯为燃料，通过改变燃烧温度和当量比，获得了较宽的燃烧条件。我们还使用氮气作为被动稀释剂来调节燃烧条件。我们计算MAC和AAE从多波长光吸收测量使用光声分光光度计和气溶胶质量负荷估计从热光学分析。从相对低温和富燃料的燃烧条件开始并逐渐升高温度和/或降低当量比，我们产生的排放物从弱吸收的棕色碳（BrC）（532 nm处的MAC（MAC（532））= 0.24 m（2）/g和AAE = 8.6）至强吸收BrC（MAC（532）= 2.1 m（2）/g和AAE = 3.1）至炭黑（BC）和强吸收BrC的混合物（MAC（532）= 0.24 m（2）/g和AAE = 8.6）。7.7 m（2）/g和AAE = 1.5）。这些研究结果表明，燃烧条件是重要的，在规定的光吸收特性的排放气溶胶。此外，无论燃料类型和燃烧条件如何，排放的气溶胶都表现出统一的连续光吸收特性，其特征可以通过MAC（532）和AAE对来表征。MAC（532）和AAE对与元素碳-有机碳比（EC/OC），这是一个代理的燃烧条件，证实了以前的研究结果，EC/OC是一个实用的基础参数化燃烧碳质气溶胶的光吸收特性。版权所有（c）2019美国气溶胶研究协会
We performed controlled combustion experiments to investigate the dependence of the mass absorption cross-section (MAC) and absorption angstrom ngstrom exponent (AAE) of combustion carbonaceous aerosol emissions on combustion conditions. Using benzene and toluene as fuels, we obtained a wide range of combustion conditions by varying the combustion temperature and equivalence ratio. We also used nitrogen as a passive diluent to tune the combustion conditions. We calculated MAC and AAE from multi-wavelength light-absorption measurements using a photoacoustic spectrophotometer and aerosol mass loadings estimated from thermal-optical analysis. Starting with relatively low-temperature and fuel-rich combustion conditions and progressively increasing the temperature and/or decreasing the equivalence ratio, we produced emissions with progressive change from weakly absorbing brown carbon (BrC) (MAC at 532 nm (MAC(532)) = 0.24 m(2)/g and AAE = 8.6) to strongly absorbing BrC (MAC(532) = 2.1 m(2)/g and AAE = 3.1) to mixtures of black carbon (BC) and strongly absorbing BrC (MAC(532) = 7.7 m(2)/g and AAE = 1.5). These findings indicate that combustion conditions are important in dictating the light-absorption properties of the emitted aerosols. Furthermore, regardless of fuel type and combustion conditions, the emitted aerosols exhibit a unified continuum of light-absorption properties that can be characterized by MAC(532) and AAE pairs. The MAC(532) and AAE pairs are well-correlated with the elemental carbon-to-organic carbon ratio (EC/OC), which is a proxy of combustion conditions, confirming previous findings that EC/OC is a practical basis for parameterizing the light-absorption properties of combustion carbonaceous aerosols. Copyright (c) 2019 American Association for Aerosol Research