Comparison and Analysis of Butanol Combustion Mechanisms

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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.