High pressure effects on the mutual sensitization of the oxidation of NO and CH4-C2H6 blends.

The mutual sensitization of the oxidation of NO and a CH(4)-C(2)H(6) (10 : 1) simulated natural gas (NG) blend was studied under fuel lean conditions (Phi = 0.5) at 50 atm and 1000-1500 K in the UIC high pressure shock tube (HPST). New experimental results were also obtained for the mutual sensitization of methane and the NG blend in the CNRS jet stirred reactor (JSR) at 10 atm. A detailed chemical kinetic model was assembled to describe the observed changes in reactivity in the CH(4) and NG blends, with and without NO, in the HPST and the JSR. The data and the validated model (tested against a variety of targets) show a reduced difference of reactivity between methane and NG blends in the presence of NO at characteristic reaction times for the JSR (250-1000 micros). However the HPST data and subsequent simulations using the validated model have revealed that at higher pressures and in the millisecond time scale regime representative of the HPST experiments (and practical combustion devices) there still persists a significant difference in reactivity between methane and NG blends in the presence of NO. The experimental data, the model development and validations and its predictions and utility as a tool to probe the NO-hydrocarbon sensitization effects under practical combustion conditions is discussed.

[1]  Michael J. Pilling,et al.  Unravelling combustion mechanisms through a quantitative understanding of elementary reactions , 2005 .

[2]  M. Su,et al.  Reflected shock tube studies of high-temperature rate constants for OH + CH4 --> CH3 + H2O and CH3 + NO2 --> CH3O + NO. , 2005, The journal of physical chemistry. A.

[3]  Melita L. Morton,et al.  IUPAC Critical Evaluation of Thermochemical Properties of Selected Radicals. Part I , 2005 .

[4]  J W Sutherland,et al.  Reflected shock tube studies of high-temperature rate constants for CH3 + O2, H2CO + O2, and OH + O2. , 2005, The journal of physical chemistry. A.

[5]  Brian S. Haynes,et al.  Kinetic and Thermodynamic Sensitivity Analysis of the NO-Sensitised Oxidation of Methane , 1996 .

[6]  R. Sivaramakrishnan,et al.  High pressure pyrolysis of toluene. 1. Experiments and modeling of toluene decomposition. , 2006, The journal of physical chemistry. A.

[7]  B. Ruscic,et al.  Reflected shock tube studies of high-temperature rate constants for OH + NO2 --> HO2 + NO and OH + HO2 --> H2O + O2. , 2006, The journal of physical chemistry. A.

[8]  P. Dagaut,et al.  The high-pressure reduction of nitric oxide by a natural gas blend , 2005 .

[9]  K. P. Lim,et al.  Rate Constants, 1100 ≤ T ≤ 2000 K, for H + NO2 → OH + NO Using Two Shock Tube Techniques: Comparison of Theory to Experiment† , 2002 .

[10]  R. Sivaramakrishnan,et al.  A high pressure model for the oxidation of toluene , 2004 .

[11]  Stephen J. Klippenstein,et al.  A THEORETICAL ANALYSIS OF THE REACTION BETWEEN ETHYL AND MOLECULAR OXYGEN , 2000 .

[12]  Michael J. Pilling,et al.  Evaluated Kinetic Data for Combustion Modelling , 1992 .

[13]  F. Egolfopoulos,et al.  An optimized kinetic model of H2/CO combustion , 2005 .

[14]  R. Sivaramakrishnan,et al.  Calibration of reaction temperatures in a very high pressure shock tube using chemical thermometers , 2001 .

[15]  Srinivasan Nk,et al.  Experimental and theoretical rate constants for CH4 + O2 → CH3 + HO2 , 2007 .

[16]  N. Marinov,et al.  An experimental and kinetic calculation of the promotion effect of hydrocarbons on the NO-NO2 conversion in a flow reactor , 1998 .

[17]  R. Sivaramakrishnan,et al.  Ethane oxidation and pyrolysis from 5 bar to 1000 bar: Experiments and simulation , 2005 .

[18]  Tiziano Faravelli,et al.  Kinetic modeling of the interactions between NO and hydrocarbons in the oxidation of hydrocarbons at low temperatures , 2003 .

[19]  L. J. Spadaccini,et al.  Ignition delay characteristics of methane fuels , 1994 .

[20]  K. Brezinsky,et al.  Design of a high-pressure single pulse shock tube for chemical kinetic investigations , 2001 .

[21]  Raymond W. Walker,et al.  Evaluated kinetic data for combustion modelling supplement I , 1994 .

[22]  A. Burcat,et al.  Third millenium ideal gas and condensed phase thermochemical database for combustion (with update from active thermochemical tables). , 2005 .

[23]  M. Su,et al.  Rate constants for H + CH4, CH3 + H2, and CH4 dissociation at high temperature , 2001 .

[24]  A. B. Bendtsen,et al.  Nitromethane dissociation: Implications for the CH3 + NO2 reaction , 1999 .

[25]  S. Davis,et al.  Combustion of CO/H2 mixtures at elevated pressures ☆ , 2007 .

[26]  Stephen J. Klippenstein,et al.  Dissociation, relaxation, and incubation in the high-temperature pyrolysis of ethane, and a successful RRKM modeling , 2005 .

[27]  A. R. Slagle,et al.  Kinetics of Reactions of H Atoms With Ethane and Chlorinated Ethanes , 2001 .

[28]  L. Curtiss,et al.  Gaussian-3 (G3) theory for molecules containing first and second-row atoms , 1998 .

[29]  A. Grillo,et al.  Shock tube investigation of methane-oxygen ignition sensitized by NO2 , 1981 .

[30]  R. A. Cox,et al.  Evaluated Kinetic, Photochemical and Heterogeneous Data for Atmospheric Chemistry: Supplement V. IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry , 1997 .

[31]  T. Ko,et al.  High-temperature photochemistry kinetics study of the reaction hydrogen atom + nitrogen dioxide .fwdarw. hydroxyl + nitric oxide from 296 to 760 K , 1991 .

[32]  P. Dagaut,et al.  Mutual sensitization of the oxidation of nitric oxide and a natural gas blend in a JSR at elevated pressure: experimental and detailed kinetic modeling study. , 2006, The journal of physical chemistry. A.

[33]  P. Dagaut,et al.  A jet-stirred reactor for kinetic studies of homogeneous gas-phase reactions at pressures up to ten atmospheres (∼1 MPa) , 1986 .

[34]  Krishnan Raghavachari,et al.  GAUSSIAN-3 THEORY USING DENSITY FUNCTIONAL GEOMETRIES AND ZERO-POINT ENERGIES , 1999 .

[35]  Philippe Dagaut,et al.  Experimental study and detailed kinetic modeling of the effect of exhaust gas on fuel combustion: mutual sensitization of the oxidation of nitric oxide and methane over extended temperature and pressure ranges , 2005 .

[36]  J. R. Smith,et al.  Detailed Chemical Kinetic Simulation of Natural Gas HCCI Combustion: Gas Composition Effects and Investigation of Control Strategies , 2001 .