Ability of Particulate Matter Index to describe sooting tendency of various gasoline formulations in a stratified-charge spark-ignition engine

Namho Kim, David Vuilleumier, Xu He, Magnus Sjöberg*

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

11 Citations (Scopus)

Abstract

The ability of particulate matter index (PMI) to describe the sooting behavior of various gasoline formulations in a stratified-charge (SC) spark-ignition engine was studied. The engine was operated at 2000 rpm with an intake pressure of 130 kPa where soot formation is known to primarily occur in the bulk gases. Exhaust soot emissions were measured for nine test fuels at various exhaust gas recirculation levels. A comparison between measured soot levels and PMI showed that PMI is a relatively poor predictor of the sooting tendency of the tested fuels under lean SC combustion. Among the fuels, the diisobutylene blend, high olefin, and E30 fuels exhibited measured soot behavior opposite of that predicted by PMI. Optical diagnostics were utilized to further investigate the in-cylinder phenomena for these three fuels. Analysis of natural luminosity and diffused back-illumination extinction imaging indicated that fuel-induced differences in the amount of soot formed are responsible for a majority of the discrepancy in measured versus predicted sooting tendency. Fuel-induced differences in soot oxidation and spray development seem to play minor roles. Because the combustion and air-fuel mixing processes for lean SC combustion are different from conventional stoichiometric operation, it was hypothesized that the PMI correlation needs to be modified to account for differences in stoichiometric air-fuel ratio and level of oxygenation between fuels. Furthermore, the role of fuel volatility in PMI possibly needs to be de-emphasized for SC operation with fuel injection into compression-heated gases.

Original languageEnglish
Pages (from-to)5791-5799
Number of pages9
JournalProceedings of the Combustion Institute
Volume38
Issue number4
DOIs
Publication statusPublished - 2021
Event38th International Symposium on Combustion, 2021 - Adelaide, Australia
Duration: 24 Jan 202129 Jan 2021

Keywords

  • Fuel sooting propensity
  • Optical diagnostics
  • Particulate Matter Index
  • Soot
  • Stratified-charge combustion

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