Application of thermodynamic analysis in reducing detailed hydrogen combustion mechanism

A set of programs has been created; it allows to carry out the thermodynamic analysis and kinetic computation of complex chemical reactions. A minimum mechanism describing the combustion kinetics of hydrogen is determined; the mechanism was used to solve an inverse task of finding parameters describing the experimental data of Kowalski at pressures of 7.4, 7.1, 6.8, 6.4 and 6.1 mm Hg. All obtained constants of direct and inverse reactions are interrelated by thermodynamic equilibrium constants. The parameters obtained for the maximum hydrogen combustion mechanism make it possible to describe well the ignition limits in Lewis and Egerton experiments. In carrying out further thermodynamic analysis, a minimal mechanism M-I is identified that corresponds to the maximum mechanism and with good accuracy describing the critical conditions of hydrogen combustion in the pressure interval 1 ÷ 200 mm Hg and temperatures of 400°C ÷ 600 °C. From the analysis of critical conditions, an analytical equation is obtained; roots of the equation give ignition limits close to the experimental ones.

hydrogen combustion kinetic, thermodynamic analysis, reduction of kinetic mechanism

Применение метода термодинамического анализа при сокращении размерности детального механизма горения водорода

Создан комплекс программ, позволяющий проводить термодинамический анализ и выполнять кинетические расчеты сложных химических реакций. Определена минимальная схема, достаточная для описания кинетики горения водорода, которая была использована при решении обратной задачи и поиска набора параметров, описывающих экспериментальные данные Ковальского при давлениях 7.4, 7.1, 6.8, 6.4 и 6.1 мм.рт.ст. Все полученные константы прямых и обратных реакций взаимосвязаны термодинамическими константами равновесия. Полученные параметры для максимальной схемы горения водорода позволяют хорошо описать пределы воспламенения в экспериментах Льюиса и Эгертона. При проведении дальнейшего термодинамического анализа выделен минимальный механизм, соответствующий максимальному и с хорошей точностью описы-вающий критические условия горения водорода в интервале давлений 1 ÷ 200 мм.рт.ст. и температур 400 °С ÷ 600 °С. Из анализа критических условий получено аналитическое уравнение, корни которого дают пределы воспламенения близкие к экспериментальным.

кинетика горения водорода, термодинамический анализ, редуцирование кинетической схемы

1. A.M.Starik, N.S.Titova, L.V.Bezgin, V.I.Kopchenov The promotion of ignition in a super-sonic H2–air mixing layer by laser-induced excitation of O2 molecules: Numerical study // Combustion and Flame, V. 156, Issue 8, August 2009, p.p. 1641-1652.
2. E.W Christiansen C.K Law C.J Sung, Steady and pulsating propagation and extinction of rich hydrogen/air flames at elevated pressures // Combustion and Flame, V. 124, Issues 1–2, January 2001, p.p 35-49
3. P. Boivin , C. Jimenez, A. L. Sanchez, F.A. Williams, An explicit reduced mechanism for H2-air combustion // Proceedings of the Combustion Institute, 33 (2011), p.p. 517–523
4. V. V. Gubernov, V. Bykov, U. Maas, Hydrogen/Air Burner-Stabilized Flames at Elevated Pressures // Combustion and Flame, V. 185, November 2017, p.p. 44-52
5. Sharath S. Girimaji, Carinne Brau, Composition-Space Behavior of Diffusion-Reaction Sys-tems // Theoretical and Computational Fluid Dynamics, April 2004, V. 17, Issue 3, p.p. 171–188
6. V. V. Gubernov, A. V. Kolobov, V. Bykov, U. Maas, Investigation of Rich Hydrogen–Air Deflagrations in Models with Detailed and Reduced Kinetic Mechanisms //Combustion and Flame, V. 168, June 2016, p.p. 32-38.
7. Maas U. Waryatz J. Ignition Processes in Hydrogen-Oxygen Mixtures // Combustion and Flame. – 1988, – V. 74. – N 1. – p.p. 53– 69.
8. Maas, U., Pope, S.B.: Simplifying Chemical Kinetics: Intrinsic Low-Dimensional Manifolds in Composition Space // Comb. Flame 88, p.p. 239–264 (1992)
9. Francesca Pianosi, Keith Beven, Jim Freer, Jim W. Hall, Jonathan Rougier, David B. Ste-phenson, Thorsten Wagener, Sensitivity Analysis of Environmental Models: A Systematic Review with Practical Workflow // Environmental Modelling & Software, V. 79, 2016, p.p. 214-232.
10. Evgeni V. Nikolaev, Jordan C. Atlas, Michael L. Shuler, Sensitivity and Control Analysis of Periodically Forced Reaction Networks Using the Green's Function Method // Journal of Theoretical Biology, V. 247, Issue 3, 2007, p.p. 442-461.
11. Писаренко Г.М., Погорелов А.Г. Планирование кинетических исследований. – М.: Наука. – 1969. – 176 с.
12. Kovalski A. A. // Phys. Z. Sow. – 1933, – V. 4, – N 5. – P. 723.
13. Lewis B., Elbe G. Combustion, flames and explosions in gases. - M.: Mir, 1968. – 592 с.
14. A. Egerton, D.R. Warren. Kinetics of the Hydrogen/Oxygen Reaction // Proc. Roy.Soc. – 1951, – V. A204, – N 2. – p.p. 465-476.
15. A.L. Sanchez, F.A. Williams / Recent Advances in Understanding of Flammability Characteristics of Hydrogen // Progress in Energy and Combustion Science. 2014, 41, p.p. 1-55
16. Dimitrov V.I. Simple kinetics. - Novosibirsk: Nauka, 1982. - 383 p.
17. Dimitrov V.I., Bykov V.I., Yablonsky G.S. The characteristics of a complex chemical reaction. In the book Burning and explosion. - M .: - Nauka. - 1977. - p. 565 –570.
18. Gorban A.N. Circumvention of equilibrium (chemical kinetics equations and their thermodynamic analysis). - Novosibirsk: Nauka, 1984. - 224 p.
19. Brin EF, Pavlov B.V. Application of one modification of the gradient extremum search method for estimating kinetic parameters. Kinetics and Catalysis. - 1975. - T. 16. - N 1. - C. 233-240.
20. Semenov N.N. Selected Works. On some problems of chemical kinetics and reactivity. - Vol. 3. - M .: Nauka, 2005 .: - 499 p.
21. V.V. Azatyan. Chain processes and nonstationarity of the surface state // Advances in Chemistry. - 1985. - V. 14. - № 1. - P. 33–60.
22. Ivanova A.N., Tarnopolsky B.L. On one approach to clarifying a number of qualitative features of the behavior of kinetic systems and its implementation on a computer // Kinetics and Catalysis. - 1979. - T. 20. No. 6. P. 1541-1548.