Internal Combustion Engines Laboratory, Thermal Engineering Department, School of Mechanical Engineering, National Technical University of Athens, 9 Heroon Polytechniou St., Zografou Campus, 15780 Athens, Greece
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, affects
the prediction of performance and emissions from a multi-zone model. The numerical study is conducted using a previously
published multi-zone model, which incorporates chemical kinetics for the estimation of reaction rates. The model
also includes sub-models for the description of heat transfer, mass transfer and crevice flow, and produces a temperature
distribution within the combustion chamber. The cases simulated and examined involve ethanol HCCI combustion in a reciprocating
internal combustion engine with various equivalence ratios. At each load two simulations are conducted with
the multi-zone model, i.e. one with each oxidation mechanism, and the results are compared to the corresponding experimental
results. The comparison of the two oxidation mechanisms includes simulation times, pressure traces, heat release
rates, composition and quantity of unburned hydrocarbons emissions, including their composition, carbon monoxide and
nitrogen oxides emissions. The reduced model decreases the simulation time by 50%. The two mechanisms produce almost
identical results as regards ignition timing. The pollutant emissions predicted are essentially the same for the two
mechanisms, with the greatest difference occurring between predicted CO emissions (~9%) at the low load cases.