In-cylinder Combustion and Soot Evolution in the Transition from Conventional CI mode to PPC
KAUST DepartmentClean Combustion Research Center
Physical Sciences and Engineering (PSE) Division
Mechanical Engineering Program
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AbstractThe present study intends to explore the in-cylinder combustion and evolution of soot emission during the transition from conventional compression ignition (CI) combustion to partially premixed combustion (PPC) at low load conditions. In-cylinder combustion images and engine-out emissions were measured in an optical engine fueled with low octane heavy naphtha fuel (RON = 50). Full cycle engine simulations were performed using a three-dimensional computational fluid dynamics code CONVERGETM, coupled with gas phase chemical kinetics, turbulence, and particulate size mimic soot model. The simulations were performed under low load conditions (IMEP ~ 2 to 3 bar) at an engine speed of 1200 rpm. The start of injection (SOI) was advanced from late (-10 CAD aTDC) to early fuel injection timings (-40 CAD aTDC) to realize the combustion transition from CI combustion to PPC. The simulation results of combustion and emission are compared with the experimental results at both CI and PPC combustion modes. The results of the study show a typical low-temperature stratified lean combustion at PPC mode, while high-temperature spray-driven combustion is evident at CI mode. The in-cylinder small intermediates species such as acetylene (C2H2), propargyl (C3H3), cyclopentadienyl (C5H5) and polycyclic aromatic hydrocarbons (PAHs) were significantly suppressed at PPC mode. Nucleation reaction of PAHs collision contributed to main soot mass production. The distribution of soot mass and particle number density was consistent with the distribution of high-temperature zones at CI and PPC combustion modes.
CitationAn Y, Mubarak Ali MJ, Raman V, Im HG, Johansson B (2018) In-cylinder Combustion and Soot Evolution in the Transition from Conventional CI mode to PPC. Energy & Fuels. Available: http://dx.doi.org/10.1021/acs.energyfuels.7b02535.
SponsorsThis work was funded by competitive research funding from King Abdullah University of Science and Technology (KAUST), and by Saudi Aramco under the FUELCOM-II program. The authors would like to thank Adrian. I. Ichim and Riyad Jambi for their technical support in conducting the engine experiments, and Convergent Science for providing licenses for the CONVERGE software.
PublisherAmerican Chemical Society (ACS)
JournalEnergy & Fuels