Ignition of a lean PRF/air mixture under RCCI/SCCI conditions: Chemical aspects
Type
ArticleKAUST Department
Clean Combustion Research CenterCombustion and Laser Diagnostics Laboratory
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2016-10-10Online Publication Date
2016-10-10Print Publication Date
2017Permanent link to this record
http://hdl.handle.net/10754/622301
Metadata
Show full item recordAbstract
Chemical aspects of the ignition of a primary reference fuel (PRF)/air mixture under reactivity controlled compression ignition (RCCI) and stratified charge compression ignition (SCCI) conditions are investigated by analyzing two-dimensional direct numerical simulation (DNS) data with chemical explosive mode (CEM) analysis. CEMA is adopted to provide fundamental insights into the ignition process by identifying controlling species and elementary reactions at different locations and times. It is found that at the first ignition delay, low-temperature chemistry (LTC) represented by the isomerization of alkylperoxy radical, chain branching reactions of keto-hydroperoxide, and H-atom abstraction of n-heptane is predominant for both RCCI and SCCI combustion. In addition, explosion index and participation index analyses together with conditional means on temperature verify that low-temperature heat release (LTHR) from local mixtures with relatively-high n-heptane concentration occurs more intensively in RCCI combustion than in SCCI combustion, which ultimately advances the overall RCCI combustion and distributes its heat release rate over time. It is also found that at the onset of the main combustion, high-temperature heat release (HTHR) occurs primarily in thin deflagrations where temperature, CO, and OH are found to be the most important species for the combustion. The conversion reaction of CO to CO and hydrogen chemistry are identified as important reactions for HTHR. The overall RCCI/SCCI combustion can be understood by mapping the variation of 2-D RCCI/SCCI combustion in temperature space onto the temporal evolution of 0-D ignition.Citation
Luong MB, Yu GH, Chung SH, Yoo CS (2016) Ignition of a lean PRF/air mixture under RCCI/SCCI conditions: Chemical aspects. Proceedings of the Combustion Institute. Available: http://dx.doi.org/10.1016/j.proci.2016.06.076.Publisher
Elsevier BVae974a485f413a2113503eed53cd6c53
10.1016/j.proci.2016.06.076