Autoignition of Butanol Isomers at Low to Intermediate Temperature and Elevated Pressure

Abstract

Autoignition delay experiments for the isomers of butanol, including n-, sec-, tert-, and iso-butanol, have been performed using a heated rapid compression machine. For a compressed pressure of 15 bar, the compressed temperatures have been varied in the range of 725-855 K for all the stoichiometric fuel/oxidizer mixtures. Over the conditions investigated in this study, the ignition delay decreases monotonically as temperature increases and exhibits single-stage characteristics. Experimental ignition delays are also compared to simulations computed using three kinetic mechanisms available in the literature. Reasonable agreement is found for three isomers (tert-, iso-, and n-butanol).

Experimental and Kinetic Studies on Ignition Delay Times of Dimethyl Ether/n-Butane/O2/Ar Mixtures

“…Figures 7 and 8 give the reaction pathway for the stoichiometric DME and nbutane mixtures at p = 1.2 atm and T = 1500 K, respectively. The timing at which 20% fuel consumed was selected by Black et al 26 and Weber et al 27 Reaction pathways of DME consumption for the DME100 and DME70 mixtures are almost the same, and reaction pathways of n-butane consumption for the DME00 and DME30 mixtures are also almost the same. This indicates that, for a specified fuel, the reaction pathways of its consumption are the same whether it is a pure fuel or the fuel blend.…”

Development of Isopentanol Reaction Mechanism Reproducing Autoignition Character at High and Low Temperatures

“…Figure is a conceptual schematic on developing a higher alcohol model. Similar to the experimental results for butanol isomers, ,,,,, it was assumed that autoignition delays of isopentanol would monotonically vary along with variation of temperature, and that a negative temperature coefficient (NTC) behavior would hardly appear. Therefore, it seemed appropriate to use the existing C 1 –C 4 alcohol models as a basis for an isopentanol model.…”

“…As mentioned in the previous section, the isopentanol model should include high- and low-temperature chemistries, which are based on models for butanol isomers and isooctane, respectively. Recent experimental work implemented by Weber et al shows low-temperature autoignition characteristics of butanol isomers at elevated pressures, and comparisons of the experiments with model predictions have also been conducted . One interesting feature is that autoignition delay times for all butanol isomers decrease monotonically as temperature increases, indicating single-stage characteristics for the given experimental conditions (stoichiometric fuel/air mixtures for 725–855 K at 1.5 MPa), while the autoignition delays are much faster than ethanol .…”

“…One interesting feature is that autoignition delay times for all butanol isomers decrease monotonically as temperature increases, indicating single-stage characteristics for the given experimental conditions (stoichiometric fuel/air mixtures for 725–855 K at 1.5 MPa), while the autoignition delays are much faster than ethanol . In addition, it is not surprising that the butanol reaction models overpredict ignition delays for n- butanol, since the n- butanol models do not include low-temperature chemistry …”

“…Recent advances in modeling of the butanol isomers are a great help when considering an isopentanol model, − since although isopentanol has five carbons, it has methyl and hydroxyl groups similar to the butanol isomers (see Figure ). It is easy to see that isopentanol and isobutanol have a similar methyl branch, and that isopentanol has four carbons in a row like n- butanol.…”