Investigation of Chemical Kinetics on Soot Formation Event of n-Heptane Spray Combustion

Kar Mun Pang, Mehdi Jangi, Xue-Song Bai, Jesper Schramm

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Abstract

In this reported work, 2-dimsensional computational fluid dynamics studies of n-heptane combustion and soot formation processes in the Sandia constant-volume vessel are carried out. The key interest here is to elucidate how the chemical kinetics affects the combustion and soot formation events. Numerical computation is performed using OpenFOAM and chemistry coordinate mapping (CCM) approach is used to expedite the calculation. Three n-heptane kinetic mechanisms with different chemistry sizes and comprehensiveness in oxidation pathways and soot precursor formation are adopted. The three examined chemical models use acetylene (C2H2), benzene ring (A1) and pyrene (A4) as soot precursor. They are henceforth addressed as nhepC2H2, nhepA1 and nhepA4, respectively for brevity. Here, a multistep soot model is coupled with the spray combustion solver to simulate the soot formation/oxidation processes. Comparison of the results shows that the simulated ignition delay times and liftoff lengths have good agreements with the experimental measurements across wide range of operating conditions when the nhepC2H2 model is implemented. The performance of this mechanism however drops in cases with low ambient temperatures. Besides, the overall soot precursor and particle distribution prediction is found to be improved with the use of A4 as soot precursor. The variation of the soot precursor production with respect to the change of ambient temperature and oxygen levels qualitatively agrees with that of the conceptual models. Also, the revised nhepC2H2 model replicates the experimental spatial soot distribution reasonably well, although the absolute soot volume fraction values are not reproduced with the default soot model constant values.
Original languageEnglish
Title of host publicationTechnical Papers - SAE 2014 World Congress & Exhibition
Number of pages16
PublisherSociety of Automotive Engineers
Publication date2014
DOIs
Publication statusPublished - 2014
EventSAE 2014 World Congress & Exhibition - Detroit, MI, United States
Duration: 8 Apr 201410 Apr 2014
http://www.sae.org/congress/

Conference

ConferenceSAE 2014 World Congress & Exhibition
CountryUnited States
CityDetroit, MI
Period08/04/201410/04/2014
Internet address
SeriesS A E Technical Papers
Number2014-01-1254
ISSN0148-7191

Cite this

Pang, K. M., Jangi, M., Bai, X-S., & Schramm, J. (2014). Investigation of Chemical Kinetics on Soot Formation Event of n-Heptane Spray Combustion. In Technical Papers - SAE 2014 World Congress & Exhibition Society of Automotive Engineers. S A E Technical Papers, No. 2014-01-1254 https://doi.org/10.4271/2014-01-1254