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Soot Oxidation in Flames: Nanostructure, Morphology, and Chemical Kinetics
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Soot Oxidation in Flames: Nanostructure, Morphology, and Chemical Kinetics. |
| 개인저자 | Anderson, Paul Marcus. |
| 단체저자명 | University of Maryland, College Park. Mechanical Engineering. |
| 발행사항 | [S.l.]: University of Maryland, College Park., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 255 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-02B. Dissertation Abstract International |
| ISBN | 9781085577397 |
| 학위논문주기 | Thesis (Ph.D.)--University of Maryland, College Park, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-02, Section: B.
Advisor: Sunderland, Peter B. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Soot produced from the combustion of hydrocarbons is of immense scientific interest owing to its deleterious effects on human health and the environment. Despite decades of research, existing soot models are accurate across only a narrow range of combustion conditions. A substantial portion of this inaccuracy is rooted in the multitude of factors affecting soot oxidation that remain ill-understood.In the current work, a novel flame system allowed soot oxidation to be observed in isolation from competing soot formation processes. Measurements tracked evolving soot structures, oxidation rates, temperatures and gas species concentrations. Transmission electron microscopy (TEM) was used to characterize soot structure at aggregate, primary particle, and nanostructural scales. For this, a program called Aerosol Image Analyzer was developed, incorporating new algorithms for processing and measuring TEM images of mass-fractal aerosols, like soot. For the first time, TEM image measurement uncertainties incorporating sample, operator, and random effects, were quantified through gage repeatability and reproducibility analysis. Successful methods for reducing operator bias were presented, and automated measurement methods from literature were tested and found to be unreliable. Measurements of surface area by N2 adsorption validated TEM as a technique for determining soot specific surface area, provided that the polydispersity and partial sintering of primary particles is taken into account.TEM measurements of soot undergoing oxidation showed continuously decreasing primary particle size distributions and increasing specific surface area. Measurements of soot aggregate morphology found a fractal dimension of 1.74 that was unchanged by oxidation. The breakup of aggregates by oxidative fragmentation was observed for the first time using methods that combined TEM analysis with laser extinction. Soot nanostructure was characterized through high resolution TEM measurements of lattice fringe length, tortuosity, orientation, and separation distance. It was observed that primary particles could be divided into an inner 80%, where lattice fringes showed greater graphitic order with increasing radial location, and an outer 20%, where this trend was reversed. While oxidation proceeded in a shrinking-sphere manner at the particle surface, the interior underwent thermal and oxidation-induced graphitization, challenging the assumption that the nanostructure of mature soot is "locked-in." This results in a surface nanostructure that is effectively unchanging from the perspective of the oxidizing gases and corresponds to a constant collision efficiency kinetics model. |
| 일반주제명 | Energy. Chemistry. Atmospheric sciences. |
| 언어 | 영어 |
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