Development and validation of a reduced multi-component mechanism for diesel engine application

摘要

Aromatics and cycloalkanes which play important roles in soot formation, are two important components in diesel. This work constructed a reduced multi-component mechanism of n-heptane-n-butylbenzene (BBZ)-methylcyclohexane (MCH)-polycyclic aromatic hydrocarbon (PAH) with 183 species and 777 reactions for diesel engine emissions and combustion prediction. Based on the reduced mechanism of n-heptane-BBZ-PAH, this multi-component diesel mechanism was constructed by merging the reduced mechanism of MCH. First, the detailed mechanism of MCH was reduced based on the methods of direct relation graph with error propagation (DRGEP), sensitivity analysis, and rate of production (ROP) analysis. Next, some most important parameters of kinetics in the mechanism were optimized by sensitivity analysis method. Further, the simplified multi-component diesel mechanism was extensively validated using the experimental values of ignition delays, species concentrations, and laminar flame speeds. The developed mechanism provides favorable prediction results, indicating that it can be used for simulating the combustion of multiple components in diesel. Finally, the developed multi-component diesel mechanism was coupled with three-dimensional computational fluid dynamic (3D-CFD), and multidimensional numerical simulations were performed in a direct-injection compression ignition (DICI) engine at EGR= 0%, 13%, 27%, 37%. The prediction results well coincided with the experimental values of combustion characteristics and emissions of soot and NOx, indicating that this multi-component diesel mechanism could be applied for predicting practical engine simulations.