Shock-tube measurements of specific reaction rates in the branched-chain H2-CO-O2 system

Brabbs, Theodore A.; Brokaw, Richard S.

doi:10.1016/s0082-0784(71)80017-6

Cited by 31 publications

(24 citation statements)

References 8 publications

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“…The conversion of CO to CO 2 by reaction with an OH radical is one of the principal oxidation reactions in the atmosphere 1 and has been the subject of many experimental [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and theoretical studies. [16][17][18][19][20][21][22][23][24][25][26][27][28] The currently accepted reaction mechanism involves a CO and OH bimolecular association to form a vibrationally excited trans-HOCO * radical, followed by a cis-trans isomerization.…”

Section: Introductionmentioning

confidence: 99%

“…[29][30][31] The non-Arrhenius behavior for the thermal rate constant has been extensively studied in experiments and theory. [3][4][5][6][7][8][9][10][11][12]16,20,21,[26][27][28] It involves a nearly activationless barrier in the entrance channel CO+ OH→ HOCO * and also in the exit channel HOCO * → H+CO 2 . There is a large H-tunneling effect in the latter, and at low temperatures there is even tunneling in the former.…”

Section: Introductionmentioning

confidence: 99%

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On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals

Chen

Marcus

2006

The Journal of Chemical Physics

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The dependence of the rate of the reaction CO+ OH→ H+CO 2 on the CO-vibrational excitation is treated here theoretically. Both the Rice-Ramsperger-Kassel-Marcus ͑RRKM͒ rate constant k RRKM and a nonstatistical modification k non ͓W.-C. Chen and R. A. Marcus, J. Chem. Phys. 123, 094307 ͑2005͒.͔ are used in the analysis. The experimentally measured rate constant shows an apparent ͑large error bars͒ decrease with increasing CO-vibrational temperature T v over the range of T v 's studied, 298-1800 K. Both k RRKM ͑T v ͒ and k non ͑T v ͒ show the same trend over the T v -range studied, but the k non ͑T v ͒ vs T v plot shows a larger effect. The various trends can be understood in simple terms. The calculated rate constant k v decreases with increasing CO vibrational quantum number v, on going from v =0 to v = 1, by factors of 1.5 and 3 in the RRKM and nonstatistical calculations, respectively. It then increases when v is increased further. These results can be regarded as a prediction when v state-selected rate constants become available.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals

Chen

Marcus

2006

The Journal of Chemical Physics

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“…1 Reflecting its importance and the unusual temperature and pressure dependence of its rate constant, the CO+ OH→ CO 2 + H reaction has been examined extensively in many experimental [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and theoretical studies, [17][18][19][20][21][22][23][24][25][26][27][28] including experimental studies over a very wide range of temperatures and pressures. [4][5][6][7][8][9][10][11][12][13]17 Nevertheless, carbon and oxygen isotope effects have been observed [29][30][31][32][33] and the anomalous effects for these heavy-atom isotopes have not yet been treated in the literature. Again, Simons and co-workers [63][64][65] observed in their molecular-beam study of the reverse reacti...…”

Section: Introductionmentioning

confidence: 99%

“…Interpretation of the oxygen isotope effects [31][32][33] is complex and is discussed in a second paper. The experimental study of the OH+ CO reaction covers a temperature range from 80 to 3150 K. [4][5][6][7][8][9][10][11][12][13]17 A marked change of activation energy occurs near 500 K. The pressure and bath gas dependence of the reaction rate have also been measured, [11][12][13][14][15]17,40 as has the pressure and temperature dependence of the OD+ CO reaction. 11,17,41 The k OH+CO / k OD+CO ratio shows a pressure-dependent H / D isotope effect.…”

Section: Introductionmentioning

confidence: 99%

On the theory of the CO+OH reaction, including H and C kinetic isotope effects

Chen

Marcus

2005

The Journal of Chemical Physics

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The effect of pressure, temperature, H / D isotopes, and C isotopes on the kinetics of the OH + CO reaction are investigated using Rice-Ramsperger-Kassel-Marcus theory. Pressure effects are treated with a step-ladder plus steady-state model and tunneling effects are included. New features include a treatment of the C isotope effect and a proposed nonstatistical effect in the reaction. The latter was prompted by existing kinetic results and molecular-beam data of Simons and co-workers ͓J. Phys. Chem. A 102, 9559 ͑1998͒; J. Chem. Phys. 112, 4557 ͑2000͒; 113, 3173 ͑2000͔͒ on incomplete intramolecular energy transfer to the highest vibrational frequency mode in HOCO * . In treating the many kinetic properties two small customary vertical adjustments of the barriers of the two transition states were made. The resulting calculations show reasonable agreement with the experimental data on ͑1͒ the pressure and temperature dependence of the H / D effect, ͑2͒ the pressure-dependent 12 C/ 13 C isotope effect, ͑3͒ the strong non-Arrhenius behavior observed at low temperatures, ͑4͒ the high-temperature data, and ͑5͒ the pressure dependence of rate constants in various bath gases. The kinetic carbon isotopic effect is usually less than 10 per mil. A striking consequence of the nonstatistical assumption is the removal of a major discrepancy in a plot of the k OH+CO / k OD+CO ratio versus pressure. A prediction is made for the temperature dependence of the OD+ CO reaction in the low-pressure limit at low temperatures.

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“…Moreover, IC engines have complex structures, so it is very difficult to install test equipment or visualization windows. To solve these problems, a variety of experimental devices such as shock tubes [4][5][6], rapid compression machines (RCMs) [7,8], and jet-stirred flow reactors [9,10] have been developed by researchers to simulate the working processes of real engines. Among these devices, the RCM has advantages that make it more suitable for research into auto-ignition of hydrocarbons in the low-to-intermediate temperature range [11][12][13]; for instance, controlling boundary and initial conditions and installing visualization windows are very easy.…”

mentioning

confidence: 99%

Experimental study of n-heptane ignition delay with carbon dioxide addition in a rapid compression machine under low-temperature conditions

et al. 2012

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The ignition delay of n-heptane homogeneous charge compression ignition (HCCI) combustion under high levels of carbon dioxide addition was quantitatively measured at elevated pressure from low to intermediate temperatures in a rapid compression machine. The experiments were conducted in the compressed temperature range 613-750 K. Both the compression ratio and fuel/air equivalence ratio were varied to investigate their effects on the ignition delay of n-heptane. Carbon dioxide was subsequently added to study the influence of the carbon dioxide level on the ignition delay of n-heptane under low-temperature conditions. It was found that carbon dioxide had different effects on the two -stages of ignition delay of n-heptane under low-temperature conditions: the concentration of carbon dioxide had little effect on the first-stage ignition time; a certain concentration of carbon dioxide accelerated the first-stage ignition but had a significantly larger impact on the second-stage ignition delay, thus increasing the overall ignition delay time. The results also showed that the first-stage ignition delay of n-heptane is only a function of temperature under low-temperature conditions. The mass of n-heptane in the combustible mixture, the equivalence ratio, and the pressure at the top dead center had little effect on the first-stage ignition time of n-heptane. rapid compression machine, n-heptane, ignition delay, low-temperature condition, carbon dioxide Citation:Guang H Y, Yang Z, Huang Z, et al. Experimental study of n-heptane ignition delay with carbon dioxide addition in a rapid compression machine under low-temperature conditions. Chin Sci Bull, 2012, 57: 39533960, doi: 10.1007/s11434-012-5331-8Environmental pressures and the energy crisis have led to increasing attention being paid to the improvement of combustion efficiency and the reduction of internal combustion (IC) engine emissions. To fundamentally improve emission levels and combustion efficiency, it is necessary to have an understanding of the combustion chemical reaction dynamics and combustion methods of IC engines. A conventional diesel engine has the advantage of a higher combustion efficiency than that of a gasoline engine, but it cannot simultaneously reduce particulate matter (PM) and NO x because of the partially rich or lean combustion in the combustion chamber. Homogeneous charge compression ignition (HCCI) has become the focus of research because of its excellent efficiency and low emission levels [1][2][3]. To control HCCI combustion, it is essential to have sufficient understanding of its ignition time and combustion speed. Processes such as fuel evaporation, diffusion, combustion, and heat transfer are very complicated in IC engines. In addition, differences exist between each working cycle, making data measurement and control of parameters between combustion cycles very difficult. Moreover, IC engines have complex structures, so it is very difficult to install test equipment or visualization windows. To solve these problems, a variety of expe...

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Shock-tube measurements of specific reaction rates in the branched-chain H2-CO-O2 system

Cited by 31 publications

References 8 publications

On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals

On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals

On the theory of the CO+OH reaction, including H and C kinetic isotope effects

Experimental study of n-heptane ignition delay with carbon dioxide addition in a rapid compression machine under low-temperature conditions

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