(660d) Combustion Characteristics of Alternative Fuels: Butanol | AIChE

(660d) Combustion Characteristics of Alternative Fuels: Butanol

Authors 

Merchant, S. - Presenter, Massachusetts Institute of Technology


Combustion
Characteristics of Alternative Fuels: Butanol

Shamel
S. Merchant,1,* Everton Fernando Zanoelo,2
Nils Hansen,3 Kevin M. Van Geem4 and William H. Green Jr.1

1  Department of Chemical Engineering,
Massachusetts Institute of Technology (MIT), Cambridge, MA, USA

2  Federal University of Paraná
(UFPR), Curitiba, PR, Brazil

3 Combustion Research Facility, Sandia National Laboratories, Livermore, CA, USA

4Laboratory
of Chemical Technology, Univ. Ghent, Ghent, Belgium

*  Corresponding author:  shamel@mit.edu

In the last few years, spurred by
growing concerns of depletion of fossil fuels and global warming, researchers
have actively tried to find alternative fuel candidates. This has led to
identification of a large number of candidate molecules available naturally or
synthesized using bioengineering. The next question is identification of a
suitable alternative fuel for commercialization, which often is an arduous task
involving rather extensive (and expensive) experimentation to assess the
performance of any proposed fuel. Moreover even if a potential alternative fuel
is identified the engine experiments provide no mechanistic insights into how
the combustion occurs, this makes it often difficult to predict combustion
characteristics of fuel under nonstandard test conditions i.e. blend of fuels,
modified or new engine concepts. It would be much more convenient if we could
just predict each proposed fuel's performance on the computer, based in large
part on first-principles calculations, and limit our experimental work to the
most promising options

Automated mechanism generation makes
it feasible to quickly construct these predictive models, but often their
accuracy of prediction is of question. In current investigation we present a
comprehensive mechanism for all butanol isomers (n-, iso-, sec- and tert-butanol). The kinetic mechanism is generated using the
open source software package Reaction Mechanism Generator (RMG)[1] and include pressure-dependent kinetics. The accuracy
of the predictive mechanism is tested by comparing against a large number of
available datasets in literature ? pyrolysis product profiles in plug flow
reactor[2] and shock tube, jet-stirred reactor mole fraction profiles[3],
opposed flow diffusion flame mole fraction profiles[4], laminar flame speeds at
different pressures[5] and autoignition delays in rapid-compression machine[6].Overall we see that for many performance parameters the
model predictions are about as accurate as the experiments, while the
prediction errors are significantly larger for other types of performance
measures. A flux and sensitivity analysis is performed to identify important parameters
in the mechanism. The success of butanol test case has validated the automatic
mechanism generation paradigm for fuel chemistry and has opened doors to quick
screening of vast number of fuel candidates (i.e iso-pentanol).

References

1.         Green,
W.H. et al.  Reaction
Mechanism Generator (RMG).  2012;
Available from: http://github.com/GreenGroup/RMG-Java.

2.         Van
Geem, K.M., et al., Accurate High-Temperature
Reaction Networks for Alternative Fuels: Butanol Isomers. Industrial
& Engineering Chemistry Research, 2010. 49(21): p. 10399-10420.

3.         Togbex, C., A. Mzex-Ahmed, and P.
Dagaut, Kinetics of Oxidation of 2-Butanol and
Isobutanol in a Jet-Stirred Reactor: Experimental Study and Modeling
Investigation. Energy & Fuels, 2010. 24(9): p.
5244-5256.

4.         Oßwald, P., et al., Combustion of butanol isomers ? A
detailed molecular beam mass spectrometry investigation of their flame
chemistry. Combustion and Flame, 2011. 158(1): p.
2-15.

5.         Veloo, P.S. and F.N. Egolfopoulos,
Flame propagation of butanol isomers/air mixtures. Proceedings
of the Combustion Institute, 2011. 33(1): p. 987-993.

6.         Weber,
B. and C.-J. Sung, A Rapid Compression Study of the Butanol Isomers at Elevated
Pressure. 7th US National Meeting of the Combustion Institute, 2011