Full metadata record
DC FieldValueLanguage
dc.contributorDepartment of Mechanical Engineeringen_US
dc.contributor.advisorChan, Tat Leung (ME)en_US
dc.creatorJiang, Xiao-
dc.identifier.urihttps://theses.lib.polyu.edu.hk/handle/200/11820-
dc.languageEnglishen_US
dc.publisherHong Kong Polytechnic Universityen_US
dc.rightsAll rights reserveden_US
dc.titleSoot formation and evolution characteristics of premixed hydrocarbon flamesen_US
dcterms.abstractSoot particles formed during the incomplete combustion of hydrocarbons not only reduce the efficiency of many combustion devices but also adversely affect the global climate, air quality and human health. The study of soot formation and evolution processes is of great importance to predict and control soot emissions. In the present study, the newly proposed and developed weighted fraction Monte Carlo (WFMC) method with reactive force fields (ReaxFF) molecular dynamics (MD) simulations are used to gain better insight into the soot formation and evolution processes.en_US
dcterms.abstractThe new WFMC method is firstly proposed by introducing the additional fraction function based on the concept of weighted numerical particles to reduce the stochastic error. The WFMC method is validated by comparing its numerical simulation results with the corresponding analytical solutions, sectional method and other Monte Carlo (MC) method schemes (i.e., direct simulation Monte Carlo (DSMC) and multi-Monte Carlo (MMC) methods) in excellent agreement. The stochastic errors obtained by different MC method schemes are further studied, and the results show that the WFMC method can significantly reduce the stochastic error for higher-order moments and particle size distribution (PSD) over the larger particle size regime with a slightly higher computational cost.en_US
dcterms.abstractThe further development of this new WFMC method is then combined with the Lagrangian particle tracking (LPT) and coupled with the detailed soot model to study soot formation and evolution in ethylene laminar premixed flames. The LPT-WFMC method is validated by both the experimental results and the numerical results of the DSMC and MMC methods. The evolution of soot number density, volume fraction and particle size distribution are investigated for different flame conditions which shows that LPT-WFMC method can extend the soot PSDs and reduce the statistical error for larger particle size regime. The effects of different parameters in the soot model on the soot PSDs are investigated by the parametric sensitivity analysis.en_US
dcterms.abstractIn order to study the atomic aspect of soot nucleation, the physical dimerization of different polycyclic aromatic hydrocarbon (PAH) structures is studied by the MD simulations. The collisional association and dissociation processes of each PAH species are investigated for different temperatures, impact parameters and orientations. The dissociation of the PAH dimers is also statistically analyzed by using the Rice-Ramsperger-Kassel (RRK) theory of unimolecular dissociation to gain a deeper insight of the energy transformation, and the contributions of intermolecular and intramolecular degrees of freedom.en_US
dcterms.abstractFinally, the soot formation and evolution processes are studied by using ReaxFF MD simulations for different carbon dioxide additions. The transformation from PAH precursors to the final soot nanoparticle under three stages of soot formation and evolution processes including nucleation, surface growth and coagulation, and graphitization is observed. The chemical effects of different carbon dioxide additions on the soot properties and reaction pathways are also analyzed.en_US
dcterms.abstractIn summary, the newly proposed and developed LPT-WFMC method in the present study has demonstrated high capability in predicting soot PSDs. Meanwhile, the ReaxFF MD simulations in the present study also provide a better understanding of the soot nucleation process.en_US
dcterms.extentxxv, 236 pages : color illustrationsen_US
dcterms.isPartOfPolyU Electronic Thesesen_US
dcterms.issued2022en_US
dcterms.educationalLevelPh.D.en_US
dcterms.educationalLevelAll Doctorateen_US
dcterms.LCSHSooten_US
dcterms.LCSHParticle size determinationen_US
dcterms.LCSHPollutantsen_US
dcterms.LCSHHydrocarbonsen_US
dcterms.LCSHHong Kong Polytechnic University -- Dissertationsen_US
dcterms.accessRightsopen accessen_US

Files in This Item:
File Description SizeFormat 
6307.pdfFor All Users4.24 MBAdobe PDFView/Open


Copyright Undertaking

As a bona fide Library user, I declare that:

  1. I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
  2. I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
  3. I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.

By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.

Show simple item record

Please use this identifier to cite or link to this item: https://theses.lib.polyu.edu.hk/handle/200/11820