Comparison and Analysis of Butanol Combustion Mechanisms

A detailed review of the performances of 24 butanol combustion
mechanisms, published between 2008 and 2020, is given using a comprehensive
experimental data collection (89,388 data points in 266 datasets from
32 publications). The data cover wide ranges of equivalence ratio
(φ = 0.38–2.67), diluent ratio (0.15–0.98), initial
temperature (672–1886 K), and pressure (0.9–90 atm).
The collection includes ignition delay time measurements in shock
tubes and rapid compression machines, concentration determinations
in shock tubes, jet-stirred reactors, flow reactors, and laminar burning
velocity measurements. The experimental data were recorded in ReSpecTh
Kinetics Data Format (RKD format) v.2.3 XML data files, which are
available in the ReSpecTh site (http://respecth.hu). The standard deviations of the measurements were estimated using
both the published experimental uncertainty and the scatter error
of the datasets determined by code Minimal Spline Fit. Mechanism CRECK
2020 was found to be the best mechanism for n-butanol (biobutanol)
combustion, while the mechanisms Sarathy 2014, Vasu 2013, and Yasunaga
2012 (in this order) were the best considering the experimental data
for all isomers. A part of the simulations failed, and to improve
the ratio of successful simulations, the code ThermCheck was created,
which detects discontinuities and nonsmoothness of thermodynamic functions
defined by NASA polynomials provided with the published mechanisms
and corrects them by tuning their coefficients. Local sensitivity
analysis applied to the experimental conditions was used to identify
the most important reaction steps of the mechanism Sarathy 2014. The
sensitivity analysis was extended to the adiabatic ignition of n-butanol–air mixtures by systematically changing
the initial temperature and pressure. All butanol combustion mechanisms
were also tested on a hydrogen combustion data collection, which indicated
that some of them were inaccurate due to their inadequate hydrogen
combustion reaction block. Suggestions were given for the improvement
of the Sarathy 2014 mechanism.