Development of a Reduced Gasoline/Hydrogenated Catalytic Biodiesel Blends Mechanism for Engine Applications

Gasoline/hydrogenated catalytic biodiesel blending fuel has been proposed to improve gasoline ignitability and combustion stability in gasoline compression ignition (GCI) engines. Comprehensive numerical simulation in GCI engine models provides useful information that can be used for efficient utilization of this promising fuel. However, the use of detailed chemical kinetic mechanisms is unfeasible. In this work, a reduced mechanism was developed for a blended fuel of gasoline/hydrogenated catalytic biodiesel (HCB). Based on the fuel composition and physicochemical properties, n-hexadecane was proposed as a surrogate fuel for HCB. Three reduction methods with error propagation extension to directed relation graph, full species sensitivity analysis and quasi steady state approximation were utilized to reduce the detailed mechanism of n-hexadecane. The reduced mechanism was coupled with a gasoline surrogate mechanism to construct gasoline/HCB surrogate mechanism. Reaction path analysis and sensitivity analyses were performed to optimize the reaction kinetic constants of several reactions. The final reduced mechanism included 82 species and 370 reactions, and was able to accurately predict various combustion characteristics such as ignition delay times, laminar flame speed and species concentrations. The reduced mechanism is also applied to 3D computational fluid dynamics to validate the prediction ability of the direct injection compression ignition engine, and the predicted results show good agreement with experimental data. The overall results suggest that the current reduced mechanism could be applied for predicting gasoline/HCB mixture in practical engine simulations.