Chemical Kinetic Modelling Study on the Influence of n-butanol blending on the Combustion, Autoignition and Knock Properties of Gasoline and its Surrogate in a Spark Ignition Engine.
Tomlin, Alison S.
KAUST DepartmentChemical Engineering Program
Clean Combustion Research Center
Combustion and Pyrolysis Chemistry (CPC) Group
Physical Science and Engineering (PSE) Division
Online Publication Date2018-08-02
Print Publication Date2018-10-18
Permanent link to this recordhttp://hdl.handle.net/10754/628419
MetadataShow full item record
AbstractThe ability of a mechanism describing the oxidation kinetics of toluene reference fuel (TRF)/n-butanol mixtures to predict the impact of n-butanol blending at 20% by volume on the autoignition and knock properties of gasoline has been investigated under conditions of a strongly supercharged spark ignition (SI) engine. Simulations were performed using the LOGEengine code for stoichiometric fuel/air mixtures at intake temperature and pressure conditions of 320 K and 1.6 bar, respectively, for a range of spark timings. At the later spark timing of 6 °CA bTDC, the predicted knock onsets for a gasoline surrogate (toluene reference fuel, TRF) and the TRF/n-butanol blend are higher compared to the measurements, which is consistent with an earlier study of ignition delay times predicted in a rapid compression machine (RCM, Agbro et al., Fuel, 2017, 187:211-219). The discrepancy between the predicted and measured knock onsets is however quite small at higher pressure and temperature conditions (spark timing of 8 °CA bTDC) and can be improved by updating a key reaction related to the toluene chemistry. The ability of the scheme to predict the influence of n-butanol blending on knock onsets requires improvement at later spark timings. The simulations highlighted that the low-intermediate temperature chemistry within the SI engine end gas, represented by the presence of a cool flame and negative temperature coefficient (NTC) phase, plays an important role in influencing the high temperature heat release and consequently the overall knock onset. This is due to its sensitisation effect (increasing of temperature and pressure) on the end gas and reduction of the time required for the high temperature heat release to occur. Therefore, accurate representation of the low-intermediate temperature chemistry is crucial for predicting knock. The engine simulations provide temperature, heat release and species profiles that link conditions in practical devices and ignition delay times predicted in an RCM. This facilitates a better understanding of the chemical processes affecting knock onsets predicted within the engine and the main reactions governing them.
CitationAgbro E, Tomlin AS, Zhang W, Burluka A, Mauss F, et al. (2018) Chemical Kinetic Modeling Study on the Influence of n-Butanol Blending on the Combustion, Autoignition, and Knock Properties of Gasoline and Its Surrogate in a Spark-Ignition Engine. Energy & Fuels. Available: http://dx.doi.org/10.1021/acs.energyfuels.8b00962.
SponsorsThe authors would like to thank COST (European Cooperation in Science and Technology www.cost.eu) for providing financial support for scientific exchange visits to LOGE Lund Combustion Engineering under the COST Action SMARTCATs (CM 1404). We also thank Inna Gorbatenko for valuable discussions and contributions. We also wish to acknowledge the Tertiary Education Trust Fund (TETFUND), Nigeria, for scholarship funding for E. Agbro. The work at King Abdullah University of Science and Technology (KAUST) was funded under the Clean Combustion Research Center (CCRC) Future Fuels program.
PublisherAmerican Chemical Society (ACS)
JournalEnergy & Fuels