Study On Physical And Chemical Characteristics Of Soot Particles Released From Combustion In A Complex Environment

The special energy structure of China determines the combustion emission is a main source of atmospheric soot. The physical and chemical property, like size, morphology, optical characteristics and so on, closely related to environmental conditions, leading soot to be the biggest source of uncertainty of atmospheric radiative transfer and visibility detection. The morphological parameters and optical properties changes of soot in different environments were analysed. The results could be the theorical basis for atmospheric radiative transfer model and the soot laser detection.A laboratory haze formation simulate platform was designed and set up for combustion emission soot study. The characteristic parameters like spectrum of UV light, wall lose of pollutants, and sealing of chamber were characterized. The error sources of the particle size distribution and density measure system was investigated and modified. The result showed, the error of size distribution measure system mainly related to scan time, particle shape, and charge state of particle. The longer scan time was, the more accurate measurement results was. For non-spherical particles, the "alignment effect" was perceived to be a main error source. For density measurement, measurement error was mainly caused by fluctuation of inlet flow, rationality of delay time, fluctuation of electrode’s rotate speed, and charge state of particle. The existence of double charged particles would cause large error which must be modified. The results improved the data quality of size distribution and density measure system.The morphology of fresh soot and the aging process of soot in air, NO2, and SO2environment were studied in the haze formation simulate platform. The relation between diameter, effective density, number of primitive carbon, and active surface area of fresh soot, and the affect fators of soot’s morphological change were analyzed. The results showed, effective density of soot decreased with the size of soot increased. The effective density, primitive carbon number and active surface area of soot were in power function relationship with particle size. The form of soot with all diameters tend to coagulate along with the aging degree deepen. In this humidity conditions, the density change of soot was mainly caused by coagulation, which might be blocked by NO2and SO2surface heterogeneous reaction. Core-shell model was used to study the scattering, absorption, and extinction efficiencies of heterogeneity haze droplets with cellulose, quartz, polystyrene, hematite, and soot inclusions, which were created by combustion emission. Besides the haze size, the parameters including size of non-absorbent nucleus, weak-absorbent one, strong-absorbent core was discussed. The results showed that scattering of a PM2.5haze droplet with a non-absorbent nucleus was stronger than that with an absorbent one. The scattering of a PM2.5haze droplet was nonlinearly dependent on its size parameter, the nucleus size, and the complex refractive index. Absorption of the droplet was determined by its relative diameter. The results could be the theoretical basis of researches about the impact of combusiton on atmospheric PM2.5optical characteristics in the high humidity environment.