Contributions to improving small ester combustion chemistry: Theory, model and experiments

High-level theoretical calculations of methyl propanoate (MP) as a representative ester molecule in biodiesel reactions were performed to obtain new measurements of species distribution in low-pressure flames and flame speeds at elevated pressure and to develop a new kinetics mechanism to gain detailed insights into its reaction kinetics. New experimental results were obtained in an extensive range of conditions including full speciation in laminar low-pressure flames at two different stoichiometries (0.8 and 1.5) using electron ionization molecular-beam mass spectrometry and flame speed measurements in a spherical confined chamber. Comparison of the experimental data to the present model shows overall improved performance. Some specific new reaction pathways to form methanol methylketene methyl acetate and acetic acid from the fuel radicals were identified and will permit more detailed insights into the combustion properties of MP.