Autoignition of Methyl Valerate at Low to Intermediate Temperatures and Elevated Pressures in a Rapid Compression Machine

Presented at the 10th US National Technical Meeting of the Combustion Institute in College Park, MD on 25 April 2017

Methyl valerate (C6H12O2, methyl pentanoate) is a methyl ester and a relevant surrogate component
for biodiesel. In this work, we present ignition delays of methyl valerate measured using a rapid
compression machine at a range of engine-relevant temperature, pressure, and equivalence ratio
conditions. The conditions we have studied include equivalence ratios from 0.25 to 2.0, temperatures
between 600-1100 K, and pressures of 15 and 30 bar. The ignition delay data demonstrate a negative
temperature coefficient region and two-stage ignition response in the temperature range of 700-800 K
for the equivalence ratios of 1.0 and 2.0 and pressure of 30 bar. In addition, the experimental
ignition delay data are compared with simulations using an existing chemical kinetic model from the
literature. The simulations with the literature model underpredict the data by factors between 2 and
10 over the entire range of the experimental data. To help determine possible reasons for the
discrepancy between simulations and experiments, a new chemical kinetic model is developed using the
Reaction Mechanism Generator (RMG) software. The agreement between the experimental data and the RMG
model is improved but still not satisfactory. Directions for future improvement of the methyl
valerate models are discussed.