Date of Award

10-30-2020

Publication Type

Master Thesis

Degree Name

M.Sc.

Department

Mechanical, Automotive, and Materials Engineering

First Advisor

Nickolas Eaves

Keywords

coflow diffusion flame, mechanism, soot, temperature effect

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Abstract

Soot particles are harmful emissions that can effect human health, the environment and contribute to global warming that is why the study of soot formation is crucial. A better understanding of soot formation can lead to more efficient combustion device designs, reduce their emissions and their impact on human health and the environment. This thesis contains two different detailed numerical studies. This work aims to find solutions to reduce soot by controlling combustion variables (Chapter 3) and understand the current ability of chemical mechanisms to predict PAH and soot concentrations (Chapter 4) by applying a detailed numerical method. The results of the numerical studies are obtained using the CoFlame code. This detailed code models the formation of soot particles in a laminar coflow C2H4/air diffusion flame by applying a fixed sectional method and accounting for processes such as reversible nucleation and condensation, soot surface growth and oxidation. The first objective is to model and investigate the effect of inlet coflow temperature on soot formation. Inlet coflow temperature plays an important role in soot formation as it can effect the reaction rates and fundamentals of soot formation process such as surface growth, nucleation and condensation. Previous studies of soot formation using the CoFlame code have focused on the modeling of the effect of pressure, diluents, and fuel types on soot formation; however, the effect of coflow temperature at lower temperatures has not been previously studied using this detailed numerical approach. The results suggest that the soot volume fraction increases in flames with a higher inlet coflow temperature. This phenomenon is associated with the high inception rates at the lower flame region and increase in the number of primary particles which will increase the possibility of more surface reaction. The second study shows the difference of two important kinetic chemical mechanisms, the chemical mechanism developed at the German Aerospace Center, referred to as the DLR mechanism, and the mechanism developed at the King Abdullah University of Science and Technology, referred to as the KAUST mechanism. The effect of these mechanisms on soot aerosol dynamics and, therefore, the formation of soot particles is studied. The results of this study suggest that there is still a need to develop a chemical mechanism which can accurately predict both the species concentration and soot volume fraction.

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