High-Temperature Autoignition of Propylene Glycol: An Experimental and Kinetic Study

Propylene glycol is a potential fuel additive with high oxygen-contained. Propylene glycol has two isomers, 1,2-propylene glycol and 1,3-propylene glycol. In order to comprehend the combustion behavior of propylene glycol, the autoignition properties were investigated experimentally behind reflected shock waves. The Ignition delay times were obtained at the temperature range of 1100-1550 K, pressures of 2, 4 and 10 atm, equivalence ratios of 0.5, 1.0 and 2.0, as well as fuel concentrations of 1.0% and 1.5%. The effects of temperature, pressure, fuel and oxygen concentrations on the ignition delay time were studied, and the corresponding quantitative relationships were obtained through linear regression analysis. A detailed oxidation mechanism of propylene glycol was proposed and verified by ignition data and species profiles. Kinetic analyses were carried out to investigate the propylene glycol oxidation. Pathway analysis indicated that H-abstraction reactions are the main consumption channels of propylene glycol. Rate of production analysis illustrated that H-abstraction reactions by H and OH radicals dominate the fuel consumption. Sensitivity analysis confirmed that besides H-abstraction reactions, C-C bond dissociation reactions express strong promoting effects on fuel ignition. Comparisons of the ignition delay time of propylene glycol, ethylene glycol and propanol were conducted.

Automated summary

Propylene glycol, a potential fuel additive, was investigated for its combustion behavior by studying the ignition delay times behind reflected shock waves. The effects of temperature, pressure, fuel and oxygen concentrations were analyzed, and a detailed oxidation mechanism was proposed. H-abstraction reactions were found to be the main consumption channels of propylene glycol, and C-C bond dissociation reactions also played a significant role. Comparison with other fuel compounds was conducted to evaluate the ignition delay time.