High-Pressure Oxy-Syngas Ignition Delay Times With CO₂ Dilution: Shock Tube Measurements and Comparison of the Performance of Kinetic Mechanisms

In this study, syngas combustion was investigated behind reflected shock waves in CO₂ bath gas to measure ignition delay times (IDT) and to probe the effects of CO₂ dilution. New syngas data were taken between pressures of 34.58–45.50 atm and temperatures of 1113–1275 K. This study provides experimental data for syngas combustion in CO₂ diluted environments: ignition studies in a shock tube (59 data points in 10 datasets). In total, these mixtures covered a range of temperatures T, pressures P, equivalence ratios φ, H₂/CO ratio θ, and CO₂ diluent concentrations. Multiple syngas combustion mechanisms exist in the literature for modeling IDTs and their performance can be assessed against data collected here. In total, twelve mechanisms were tested and presented in this work. All mechanisms need improvements at higher pressures for accurately predicting the measured IDTs. At lower pressures, some of the models agreed relatively well with the data. Some mechanisms predicted IDTs which were two orders of magnitudes different from the measurements. This suggests that there is behavior that has not been fully understood on the kinetic models and is inaccurate in predicting CO₂ diluted environments for syngas combustion. To the best of our knowledge, current data are the first syngas IDTs measurements close to 50 atm under highly CO₂ diluted (85% per vol.) conditions.