Reduced Chemistry for Butanol Isomers at Engine-Relevant Conditions

Abstract

Butanol has received significant research attention as the second-generation biofuel in the past few years. In the present study, skeletal mechanisms for four butanol isomers were generated from two widely accepted, well-validated detailed chemical kinetic models for the butanol isomers. The detailed models were reduced using a two-stage approach consisting of the directed relation graph with error propagation and sensitivity analysis. During the reduction process, issues encountered with pressure-dependent reactions formulated using the logarithmic pressure interpolation approach were discussed, with recommendations made to avoid ambiguity in its future implementation in mechanism development. The performances of the skeletal mechanisms generated here were compared with those of detailed mechanisms in simulations of autoignition delay times, laminar flame speeds, and perfectly stirred reactor temperature response curves and extinction residence times, over a wide range of pressures, temperatures, 1 arXiv:1706.02043v1 [physics.chem-ph] 7 Jun 2017 and equivalence ratios. Good agreement was observed between the detailed and skeletal mechanisms, demonstrating the adequacy of the resulting reduced chemistry for all the butanol isomers in predicting global combustion phenomena. The skeletal mechanisms also closely predicted the time-histories of fuel mass fractions in homogeneous compression-ignition engine simulations. Finally, the performances of the butanol isomers were compared with that of a gasoline surrogate with an anti-knock index of 87 in a homogeneous compression-ignition engine simulation. The gasoline surrogate consumed faster than any of the butanol isomers, and tert-butanol had the slowest fuel consumption rate; n-butanol and isobutanol came closest to matching the gasoline, but the two literature chemical kinetic models predicted different orderings.

Ethanol Dehydrogenation: A Reaction Path Study by Means of Temporal Analysis of Products

“…Recently, basic research into new catalysts for the synthesis of higher alcohols on a renewable basis via aldolic condensation has been gaining increasing attention [1][2][3][4][5][6]. Amongst these alcohols, iso-butanol in particular has been identified as very promising from various perspectives.…”

Pressure-dependent kinetics of peroxy radicals formed in isobutanol combustion

“…The reaction rates from these calculations can be compared to estimates from the detailed isobutanol mechanism by Sarathy et al 15 Two other isobutanol mechanisms, published by Hui et al 7 and Merchant et al, 11 do not include explicit representation of peroxy radicals, so these cannot be compared directly to the calculations here.…”

“…Detailed isobutanol mechanisms typically deviate more from experiments than do models of n-butanol, tert-butanol, and sec-butanol. 7,8 Multiple inter-model comparisons using detailed isobutanol models have showed that at lean, low-temperature conditions the models yield a wide range of ignition timings that deviate from experimental ignition delay measurements in homogeneous charge compression 9 and shock tube setups. 10 One mechanism shows the largest deviations from experiments below 850 K and at fuel lean conditions, indicating that the dependence on O 2 might be incorrectly described.…”

Elucidating the Influence of the d-Band Center on the Synthesis of Isobutanol

“…I-butanol is a versatile base chemical and has also been tested as a carbon-neutral fuel [25]. Thanks to its higher octane numbers, lower soot production, and higher compressibility in internal combustion engines, it has emerged as a superior fuel over n-butanol [26][27][28].…”