Exploring the Flame Chemistry of C5 Tetrahydrofuranic Biofuels: 2 -Tetrahydrofurfuryl Alcohol and 2‑Methyltetrahydrofuran
Recently, the combustion chemistry of tetrahydrofurfurylalcohol (THFA), a potential biofuel, was investigated in a stoichiometric 20 mol % THFA/methane co-fueled premixed flame at 5.3 kPa by our group (Tran, L.-S.; Carstensen, H.-H.; Foo, K. K.; Lamoureux, N.; Gosselin, S.; Gasnot, L.; El-Bakali, A.; Desgroux, P. Experimental and modeling study of the high-temperature combustion chemistry of tetrahydrofurfuryl alcohol. Proc. Combust. Inst. 2021, 38,631−640, 10.1016/j.proci.2020.07.057). With regard to this, we continue to further explore the combustion chemistry of this biofuel to understand the influence of THFA-doping amounts on the flame chemistry of its mixture with methane and the impact of the alcohol function of THFA on the product spectrum compared to its nonalcoholic fuel counterpart, i.e., 2-methyltetrahydrofuran (MTHF). To accomplish the above said objective, a methane flame, a 10% THFA/methane flame, and a 20% MTHF/methane flame were additionally analyzed at similar conditions using gas chromatography for quantitative species detection and NO laser-induced fluorescence thermometry. More than 40 species (reactants, CO, CO2, H2O, H2, and about 14 hydrocarbons as well as 26 oxygenated intermediates up to 5 carbon atoms) were quantified for each doped biofuel flame. The product distributions and consumption pathways of THFA are similar for the 10 and 20% THFA-doped flames. The maximum yields of most products increase linearly with the amount of doped THFA. However, some species do not follow this trend, indicating interaction chemistry between methane and THFA, which is found to be mainly caused by the reaction of the methyl radical. The difference in the chemical structure in THFA and MTHF has no notable impact on the mole fractions of CO, CO2, H2O, and H2, but significant differences exist for the yields of intermediate species. The doped THFA flame produces more aldehydes, alcohols, and ethers but forms clearly less ketones and hydrocarbons. A slightly upgraded version of our previous kinetic model reproduces most experimental data well and is able to explain the observed differences in intermediate production.