Comparative Autoignition Trends in Butanol Isomers at Elevated Pressure
AbstractAutoignition experiments of stoichiometric mixtures of s-, t-, and i-butanol in air have been performed using a heated rapid compression machine (RCM). At compressed pressures of 15 and 30 bar and for compressed temperatures in the range 715-910 K, no evidence of a negative temperature coefficient region in terms of ignition delay response is found. The present experimental results are also compared with previously reported RCM data of n-butanol in air. The order of reactivity of the butanols is n-butanol > s-butanol ≈ i-butanol > t-butanol at the lower pressure but changes to n-butanol > t-butanol > s-butanol > i-butanol at higher pressure. In addition, t-butanol shows preignition heat release behavior, which is especially evident at higher pressures. To help identify the controlling chemistry leading to this preignition heat release, off-stoichiometric experiments are further performed at 30 bar compressed pressure, for t-butanol at φ = 0.5 and φ = 2.0 in air. For these experiments, higher fuel loading (i.e., φ = 2.0) causes greater preignition heat release (as indicated by greater pressure rise) than the stoichiometric or φ = 0.5 cases. Comparison of the experimental ignition delays with the simulated results using two literature kinetic mechanisms shows generally good agreement, and one mechanism is further used to explore and compare the fuel decomposition pathways of butanol isomers. Using this mechanism, the importance of peroxy chemistry in the autoignition of the butanol isomers is highlighted and discussed. © 2013 American Chemical Society.
CitationWeber BW, Sung C-J (2013) Comparative Autoignition Trends in Butanol Isomers at Elevated Pressure. Energy Fuels 27: 1688–1698. Available: http://dx.doi.org/10.1021/ef302195c.
SponsorsThe authors acknowledge support from the Combustion Energy Frontier Research Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award number DE-SC0001198. The authors gratefully acknowledge Dr. William Green and Shamel Merchant of the Massachusetts Institute of Technology for providing their mechanism prior to publication and for useful discussions and Dr. Mani Sarathy of King Abdullah University of Science and Technology for very helpful discussions.
PublisherAmerican Chemical Society (ACS)
JournalEnergy & Fuels