A comprehensive experimental and modeling study of iso-pentanol combustion

Biofuels are considered as potentially attractive alternative fuels that can reduce pollutant emissions. Ethanol is the most commonly used biofuel to power automobiles, but ethanol has several disadvantages such as low energy density, high O/C ratio, and high hygroscopicity. Iso-pentanol is one of nextgeneration biofuels that can be used as an alternative fuel in combustion engines because of higher energy density and lower hygroscopicity compared to ethanol. In the present study, new experimental data for iso-pentanol in shock tube, rapid compression machine, jet stirred reactor, and counterflow diffusion flame are presented. A detailed chemical kinetic model for iso-pentanol oxidation was developed including high- and lowerature chemistry for a better understanding the combustion characteristics of higher alcohols. First, bond dissociation energies were calculated using ab initio methods. The proposed rate constants were based on a previously presented model for butanol isomers and n-pentanol. The model was validated against new and existing experimental data in shock tubes, rapid compression machines, jet stirred reactors, premixed flames, and non-premixed flames. Shock tube ignition delay times were measured for iso-pentanol/air mixtures at equivalence ratios of 0.5, 1.0, and 2.0, at temperatures ranging from 790 to 1252 K, and at nominal pressures of 40 and 60 bar. New jet stirred reactor experiments are reported at 5 atm and four different equivalence ratios. Rapid compression machine ignition delay data was obtained at 40 bar, three equivalence ratios, and temperatures below 800 K. The present mechanism shows good agreement with the data obtained from a wide variety of experimental conditions. Premixed laminar flame speeds and non-premixed extinction strain rates were obtained using the counterflow configuration. The method of direct relation graph (DRG) with expert knowledge (DRGX) was employed to eliminate unimportant species and reactions in the detailed isopentanol mechanism and then predict non-premixed flame behavior. In additions, reaction path and temperature A-factor sensitivity analyses were conducted for identifying key reactions.