GLOBAL UNCERTAINTY AND SENSITIVITY ANALYSIS OF A REDUCED CHEMICAL KINETIC MECHANISM OF A GASOLINE, N-BUTANOL BLEND IN A HIGH PRESSURE RAPID COMPRESSION MACHINE

Edirin Agbro

Abstract


A detailed evaluation of a recently developed combined n-butanol/toluene reference fuel (TRF) reduced chemical kinetic mechanism (Agbro, 2017) describing the low temperature oxidation of n-butanol, gasoline and a gasoline/n-butanol blend was performed using both global uncertainty and sensitivity methods with ignition delays as the predicted output for the temperature range 678 - 858 K, and an equivalence ratio of 1 at 20 bar. A global sampling technique was applied in the simulations in order to quantify the uncertainties of the predicted ignition delays when incorporating the effects of uncertainties in forward rate constants in the simulations. In addition, a variance-based global sensitivity analysis using a high dimensional model representation (HDMR) method was carried out to understand and rank the parameters responsible for the predicted uncertainties. The results showed that uncertainties in predicting key target quantities for the various fuels studied are currently large but driven by few reactions. Global sensitivity analysis of the mechanism based on predicted ignition delays of stoichiometric TRF mixtures, showed the toluene + OH route = phenol + CH3 to be among the most dominant pathways in terms of the predicted output uncertainties but an update on the mechanism based on recent data from the study of Seta led to the toluene + OH hydrogen abstraction reaction becoming the most dominant reaction as expected. For the TRF/n-butanol blend, hydrogen abstraction reactions by OH from n-butanol appear to be key in predicting the effect of blending. Uncertainties in the temperature dependence of relative abstraction rates from the α and γ sites may still be present within current mechanisms, and in particular may affect the ability of the mechanisms to capture the low temperature delay times for n-butanol. Further studies of the product channels for n-butanol + OH for temperatures of relevance to combustion applications could help to improve current mechanisms. At higher temperatures, the reactions of HO2 and that of formaldehyde with OH also became critical and attempts to reduce uncertainties in the temperature dependent rates of these reactions would be useful.

References


AGARWAL, A. K. 2007. Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines. Progress in energy and combustion science, 33, 233-271.

AGBRO, E. 2017. Experimental and chemical kinetic modelling study on the combustion of alternative fuels in fundamental systems and practical engines. PhD thesis, The University of Leeds.

AGBRO, E. & TOMLIN, A. S. 2017. Low temperature oxidation of n-butanol: Key uncertainties and constraints in kinetics. Fuel, 207, 776-789.

AGBRO, E., TOMLIN, A. S., LAWES, M., PARK, S. & SARATHY, S. M. 2017. The influence of n-butanol blending on the ignition delay times of gasoline and its surrogate at high pressures. Fuel, 187, 211-219.

ANDRAE, J. C. G. 2008. Development of a detailed kinetic model for gasoline surrogate fuels. Fuel, 87, 2013-2022.

ANDRAE, J. C. G., BJÖRNBOM, P., CRACKNELL, R. F. & KALGHATGI, G. T. 2007. Autoignition of toluene reference fuels at high pressures modeled with detailed chemical kinetics. Combustion and Flame, 149, 2-24.

BAULCH, D. L. 1997. Kinetic Databases. In: PILLING, M. J. (ed.) Comprehensive Chemical Kinetics: Low Temperature Combustion and Auto-ignition. Elservier.

BAULCH, D. L., BOWMAN, C. T., COBOS, C. J., COX, R. A., JUST, T. H., KERR, J. A., PILLING, M. J., STOCKER, D., TROE, J., TSANG, W., WALKER, R. W. & WARNATZ, J. 2005. Evaluated kinetic data for combustion modeling: supplement II. Journal of Physical and Chemical Reference Data, 34, 757-1397.

BAULCH, D. L., COBOS, C. J., COX, R. A., ESSER, C., FRANK, P., JUST, T., KERR, J. A., PILLING, M. J., TROE, J., WALKER, R. W. & WARNATZ, J. 1992. Evaluated Kinetic Data for Combustion Modelling. Journal of Physical and Chemical Reference Data, 21, 411-734.

BAULCH, D. L., COBOS, C. J., COX, R. A., FRANK, J. H., HAYMAN, G., JUST, T. H., KERR, J. A., MURRELS, T., PILLING, M. J.; TROE, J., WALKER, B. F. & WARNATZ, J. 1994. Summary table of evaluated kinetic data for combustion modeling: Supplement 1. Combustion and Flame, 59-79.

DERNOTTE, J., MOUNAIM-ROUSSELLE, C., HALTER, F. & SEERS, P. 2009. Evaluation of butanol–gasoline blends in a port fuel-injection, spark-ignition engine. Oil & Gas Science and Technology–Revue de l’Institut Français du Pétrole, 65, 345-351.

GLAUDE, P. A., CONRAUD, V., FOURNET, R., BATTIN-LECLERC, F., CÔME, G. M., SCACCHI, G., DAGAUT, P. & CATHONNET, M. 2002. Modeling the Oxidation of Mixtures of Primary Reference Automobile Fuels. Energy & Fuels, 16, 1186-1195.

GOODWIN, D. M., N; MOFFAT, H; SPETH, R 2013. CANTERA: an object-oriented software toolit for chemical kinetics, thermodynamics, and transport processes, https://code.google.com/p/cantera.

MEHL, M., PITZ, W. J., WESTBROOK, C. K. & CURRAN, H. J. 2011. Kinetic modeling of gasoline surrogate components and mixtures under engine conditions. Proceedings of the Combustion Institute, 33, 193-200.

NAIK, C. V., PITZ, W. J., WESTBROOK, C. K., SJÖBERG, M., DEC, J. E., ORME, J., CURRAN, H. J. & SIMMIE, J. M. 2005. Detailed Chemical Kinetic Modeling of Surrogate Fuels for Gasoline and Application to an HCCI Engine. SAE International.

REACTION DESIGN 2011. CHEMKIN-PRO, San Diego.

SARATHY, S. M., OßWALD, P., HANSEN, N. & KOHSE-HÖINGHAUS, K. 2014. Alcohol combustion chemistry. Progress in Energy and Combustion Science, 44, 40-102.

SETA, T., NAKAJIMA, M. & MIYOSHI, A. 2006. High-temperature reactions of OH radicals with benzene and toluene. The Journal of Physical Chemistry A, 110, 5081-5090.

SZWAJA, S. & NABER, J. D. 2010. Combustion of n-butanol in a spark-ignition IC engine. Fuel, 89, 1573-1582.

TANAKA, S., AYALA, F. & KECK, J. C. 2003. A reduced chemical kinetic model for HCCI combustion of primary reference fuels in a rapid compression machine. Combustion and Flame, 133, 467-481.

TOMLIN, A. S. 2006. The use of global uncertainty methods for the evaluation of combustion mechanisms. Reliability Engineering & System Safety, 91, 1219-1231.

TOMLIN, A. S. 2013. The role of sensitivity and uncertainty analysis in combustion modelling. Proceedings of the Combustion Institute, 34, 159-176.

TOMLIN, A. S. & TURANYI, T. 2013. Investigation and Improvement of Mechanism using Sensitivity Analysis and Optimization. In: BATTIN-LECLERC, F., SIMMIE, J. M. & BLUROCK, E. (eds.) Cleaner Combustion: Developing Detailed Chemical Kinetic Models

London: Springer-Verlag.

TSANG, W. 1992. Chemical Kinetic Data Base for Propellant Combustion. II. Reactions Involving CN, NCO, and HNCO. Journal of Physical and Chemical Reference Data, 21, 753-791.

TSANG, W. & HAMPSON, R. F. 1986. Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related Compounds. Journal of Physical and Chemical Reference Data, 15, 1087-1279.

WEBER, B. W. & SUNG, C.-J. 2013. Comparative Autoignition Trends in Butanol Isomers at Elevated Pressure. Energy & Fuels, 27, 1688-1698.

WESTBROOK, C. K., WARNATZ, J. & PITZ, W. J. 1988. A detailed chemical kinetic reaction mechanism for the oxidation of iso-octane and n-heptane over an extended temperature range and its application to analysis of engine knock. Symposium (International) on Combustion, 22, 893-901.

WIGG, B. 2011. A Study on Emission of Butanol using a Spark Ignition Engine and their Reduction Using Electrostatically Assisted Injection. PhD, University of Ilinois, Urbana.

ZIEHN, T. & TOMLIN, A. 2009. GUI–HDMR–A software tool for global sensitivity analysis of complex models. Environmental Modelling & Software, 24, 775-785.