Combustion and Flame, Vol.162, No.11, 4283-4303, 2015
Pyrolysis and combustion chemistry of tetrahydropyran: Experimental and modeling study
This paper reports new experimental and numerical data for the pyrolysis and combustion of tetrahydropyran (THP) - a model component for next-generation heterocyclic oxygenated fuels. Pyrolysis experiments were performed using a plug flow reactor at 170 kPa, over the temperature range 913-1133 K at residence times of approximately 0.5 and 0.2 s, with 90% and 96% N-2 dilution, respectively. THP combustion was investigated in two premixed flat flame burners and in a shock tube. The first premixed flame burner was operated at 6.7 kPa and was used to study detailed flame structures. Two equivalence ratios (1.0 and 1.3) were investigated with a 78% argon dilution. Ethylene, 1,3-butadiene, formaldehyde, and acrolein were the most important intermediates at both pyrolysis and combustion conditions, while the yield of aromatic species was negligible under flame conditions. Laminar burning velocities of THP-air mixtures using the heat flux method were measured at 298,358 and 398 K and equivalence ratios from 0.55 to 1.50. Finally, ignition delay times of THP-oxygen-argon mixtures were measured behind reflected shock waves at temperatures from 1350 to 1613 K, pressures from 885 to 914 kPa and mixtures containing 0.15-1% fuel at equivalence ratios between 0.5 and 2.0. A new detailed kinetic model for the THP pyrolysis/combustion was developed by EX-GAS, complemented with theoretical calculations for the determining reactions. Good agreements between simulations and acquired experimental data were observed. Reaction path analysis shows that THP is mainly consumed by H-abstractions at both pyrolysis and combustion conditions. The pyrolysis simulations are very sensitive to the unimolecular initiations involving C-C and C-O bond fissions, whereas these reactions play only a very minor role under combustion conditions. (C) 2015 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
Keywords:Biofuel;Tetrahydropyran;Pyrolysis;Laminar premixed flame;Ignition delay times;Detailed kinetic model