Comparison of a Detailed and a Reduced Ethanol Oxidation Mechanism in HCCI Combustion Using a Multi-Zone Model

摘要

The subject of the present study is the comparison of a detailed and a reduced ethanol oxidation mechanism.The main scope is to determine whether the reduction of species and reactions, which reduces the simulation time, affectsthe prediction of performance and emissions from a multi-zone model. The numerical study is conducted using a previouslypublished multi-zone model, which incorporates chemical kinetics for the estimation of reaction rates. The modelalso includes sub-models for the description of heat transfer, mass transfer and crevice flow, and produces a temperaturedistribution within the combustion chamber. The cases simulated and examined involve ethanol HCCI combustion in a reciprocatinginternal combustion engine with various equivalence ratios. At each load two simulations are conducted withthe multi-zone model, i.e. one with each oxidation mechanism, and the results are compared to the corresponding experimentalresults. The comparison of the two oxidation mechanisms includes simulation times, pressure traces, heat releaserates, composition and quantity of unburned hydrocarbons emissions, including their composition, carbon monoxide andnitrogen oxides emissions. The reduced model decreases the simulation time by 50%. The two mechanisms produce almostidentical results as regards ignition timing. The pollutant emissions predicted are essentially the same for the twomechanisms, with the greatest difference occurring between predicted CO emissions (~9%) at the low load cases.