Abstract

The miniCAST 5201 black carbon (BC) generator is a novel soot generator able to produce soot particles with a wide range of properties in a stable and reproducible manner. In this study, particles generated with diffusion and premixed flames were comprehensively analyzed, with a special focus on particle morphology, nanostructure, and optical properties. It was found that aggregate BC particles with a mean electrical mobility diameter of about 160 nm generated with an overall near-stoichiometric diffusion flame consist of primary particles with turbostratic layers and onion-like structures. Moreover, they possessed an absorption Ångström exponent (AAE) close to 1, low single scattering albedo (SSA), and a mass absorption cross-section MAC_870nm,total (calculated from photoacoustic absorption coefficient and total particle mass) of 4.3 m²/g. With premixed flames under fuel-lean conditions, particles with mean mobility diameters of 50 nm, 75 nm, and 100 nm could be generated with high elemental carbon to total carbon mass fractions (>85%). These particles had a high structural order, exhibited an AAE of 1.1–1.2, low SSA and MAC_870nm,total of 3.0–3.3 m²/g. The similarities of the properties of the miniCAST generated soot particles to real-world engine-emitted soot particles indicate that the miniCAST 5201 BC generator is a very promising source of reference aerosols for the calibration of BC diagnostic instruments and engine-exhaust particle counters.

摘要

miniCAST 5201 黑碳 (BC) 发生器是一种新型烟尘发生器，能够以稳定和可重复的方式生产具有广泛特性的烟尘颗粒。在这项研究中，综合分析了扩散和预混火焰产生的颗粒，特别关注颗粒形态、纳米结构和光学特性。发现平均电迁移率直径约为 160 nm 的聚集体 BC 颗粒由整体接近化学计量的扩散火焰产生，由具有湍流层和洋葱状结构的初级颗粒组成。此外，它们具有接近 1 的吸收 Ångström 指数 (AAE)、低单散射反照率 (SSA) 和质量吸收截面 MAC _{870nm，总计}（由光声吸收系数和总颗粒质量计算）为 4.3 m ² /g。在贫燃料条件下使用预混火焰，可以产生平均流动直径为 50 nm、75 nm 和 100 nm 的粒子，其中元素碳与总碳的质量分数（> 85%）高。这些颗粒具有高结构有序性，AAE 为 1.1-1.2，SSA 和 MAC 低_{870nm，总计}3.0-3.3 m ² /g。miniCAST 生成的烟尘颗粒与真实世界发动机排放的烟尘颗粒的特性相似，这表明 miniCAST 5201 BC 发生器是非常有前途的参考气溶胶来源，用于校准 BC 诊断仪器和发动机排气颗粒计数器。