On the Response of Nascent Soot Nanostructure and Oxidative Reactivity to Photoflash Exposure

Abstract

Soot particles are a kind of major pollutant from fuel combustion. To enrich the understanding of soot, this work focuses on investigating detailed influences of instantaneous external irradiation (conventional photoflash exposure) on nanostructure as well as oxidation reactivity of nascent soot particles. By detailed soot characterizations flash can reduce the mass of soot and soot nanostructure can be reconstructed substantially without burning. After flash, the degree of soot crystallization increases while the soot reactive rate decreases and the activation energy increases. In addition, nanostructure and oxidative reactivity of soot in air and Ar after flash are different due to their different thermal conductivities.

Nanoscale Characteristics and Reactivity of Nascent Soot from n-Heptane/2,5-Dimethylfuran Inverse Diffusion Flames with/without Magnetic Fields

“…In the HRTEM images, a measure of the physical extent of the atomic carbon layer planes was presented as fringe length, and a value of curvature of the fringes arising from odd numbered five-and seven-membered ring structures was signed as fringe tortuosity [64][65][66][67][68][69]. It was reported that the fringe length and tortuosity obtained from HRTEM images could change with a long exposure time of the electron beam irradiation [70].…”

“…The image processing method, consisting of digital image processing and fringe characterization, was similar to the one developed by Maria and Yehliu et al [64][65][66][67]. The image processing run in MATLAB (2014) software with customized algorithms including several operations, such as negative transformation, region of interest selection, contrast enhancement, Gaussian lowpass filter, top-hat transformation, thresholding to obtain a binary image, morphological modification, skeletonization, and short fringes and boundary fringes removal.…”

“…The test uncertainty was ±5% error which derived from a set of isothermal oxidation experiments. Two separate experiments were carried out to verify the reproducibility of the TGA results [21,22,64].…”

“…The instrument with scan range of 10-110 • was used at scan step size of 0.02 • and scan speed of 0.2 s/step [22,64].…”

Effects of Flame Configuration and Soot Aging on Soot Nanostructure and Reactivity in n-Butanol-Doped Ethylene Diffusion Flames

“…In addition, Vander Wal further explored the impact of soot nanostructure covering fringe length, tortuosity and interval space of the carbon lamellae on soot oxidation behavior and illustrated that soot which showed higher oxidation rates had shorter fringe length and larger tortuosity and interval space. Numerous recent studies have also been conducted to investigate the relation between soot nanostructure and oxidation rate, and all concluded soot reactivity strongly depended on initial soot nanostructure. − …”