Heat release and radical recombination in premixed fuel-lean flames of H2+ O2+ N2. Rate constants for H + OH + M ? H2O + M and HO2+ OH ? H2O + O2

Goodings, John M.; Hayhurst, A.N.

doi:10.1039/f29888400745

Cited by 44 publications

(41 citation statements)

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“…In fact, the studies of Goodings and Hayhurst (1988) and Srinivisan et al (2006) show very little temperature dependence of the rate for (R8) for temperatures greater than about 1300 K. Here we report new least-squares analyses of available experimental data to obtain rate expressions constrained by a high temperature limiting value. First, we assumed that up to 800 K the rate of (R8) follows the temperature dependence proposed by Keyser (1988).…”

Section: Ho 2 +Oh=h 2 O+o 2 (R8)mentioning

confidence: 99%

“…fitted experimental data from a number of studies (DeMore, 1982;Goodings and Hayhurst, 1988;Hippler et al, 1995;Hippler and Troe, 1992;Kappel et al, 2002;Keyser, 1988; Li et al, 1980; Peters and Mahnen, 1973). The fit gives larger weight to the data of Hippler et al (1995) rather than to the more recent, and arguably more reliable, measurements of Kappel et al (2002).…”

Section: Update On Co+ho 2 Reaction Rate Correlationmentioning

confidence: 99%

“…fitted experimental data from a number of studies (DeMore, 1982;Goodings and Hayhurst, 1988;Hippler et al, 1995;Hippler and Troe, 1992;Kappel et al, 2002;Keyser, 1988;Lii et al, 1980;Peters and Mahnen, 1973) by the following expression: Fig. 5 along with available experimental data.…”

Section: Ho 2 +Oh=h 2 O+o 2 (R8)mentioning

confidence: 99%

“…In Chaos and Dryer (2008), we report two new least-squares analyses of available experimental data to obtain rate expressions constrained by a high temperature limiting value (Goodings and Hayhurst, 1988;Srinivisan et al, 2006), one using the measurements of Hippler et al (1995), who measured a rate minimum near 1240 K, and a second using the data of Kappel et al (2002), who located the rate minimum near 1010 K. We found that reasonable predictions of the high pressure oxidation data of can only be obtained using values of the rate for (R7) predicted by the correlation developed using the Hippler et al (1995) results: Using the Li et al (2007) CSP analyses applied to the conditions of , we note above that (R7) is only important during chemical induction at all pressures. As the reacting system evolves, (R8) becomes much more important than (R7) in determining the overall rate of reaction since it is the major direct source of OH at high pressures for reacting with CO through (R4).…”

Section: Update On Ho 2 + Oh = H 2 O + O 2 Reaction Rate Correlationmentioning

confidence: 99%

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Chemical Kinetics in Support of Syngas Turbine Combustion

Dryer¹

2007

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Executive SummaryThis document is the final report on an overall program formulated to extend our prior work in developing and validating kinetic models for the CO/hydrogen/oxygen reaction by carefully analyzing the individual and interactive behavior of specific elementary and subsets of elementary reactions at conditions of interest to syngas combustion in gas turbines. A summary of the tasks performed under this work are: 1. Determine experimentally the third body efficiencies in H+O 2 +M = HO 2 +M (R1) for CO 2 Results are summarized in this document and its appendices. Three archival papers which contain a majority of the research results have appeared. Those results not published elsewhere are highlighted here, and will appear as part of future publications. Portions of the work appearing in the above publications were also supported in part by the Department of Energy under Grant No. DE-FG02-86ER-13503.As a result of and during the research under the present contract, we became aware of other reported results that revealed substantial differences between experimental characterizations of ignition delays for syngas mixtures and ignition delay predictions based upon homogenous kinetic modeling. We adjusted emphasis of Task 2 to understand the source of these noted disparities because of their key importance to developing lean premixed combustion technologies of syngas turbine applications. In performing Task 3, we also suggest for the first time the very significant effect that metal carbonyls may have on syngas combustion properties. This work is fully detailed in Appendix C. The work on metal carbonyl effects is entirely computational in nature. Pursuit of experimental verification of these interactions was beyond the scope of the present work.3 Results over this Progress Period ApproachThe present research further extended our prior work in developing and validating kinetic models for the CO/hydrogen/oxygen principally studied under Department of Energy Grant No. DE-FG02-86ER-13503, by providing additional experimental data using a Variable Pressure Flow Reactor (VPFR) on the collisional efficiencies of water and carbon dioxide in the reaction H+O 2 +M = HO 2 + M (R1) by carefully analyzing the individual and interactive behavior of specific elementary and subsets of elementary reactions at the conditions of interest, and by extending computational model comparisons with data obtained in this program and those appearing in the literature since 2004 to further test and refine the model at conditions relevant to gas turbine applications. Additionally, syngas contaminant species such as small hydrocarbons (e.g., methane) and other combustion gas components (e.g. NO x ) have been identified and it is suspected that these contaminants may affect syngas chemistry in gas turbine applications, particularly in mixing regions of entering fuel and air. These contaminants can have significant influence on some of the kinetic behavior. The initial research plan was to investigate only the effects of small local amo...

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Section: Ho 2 +Oh=h 2 O+o 2 (R8)mentioning

confidence: 99%

Section: Update On Co+ho 2 Reaction Rate Correlationmentioning

confidence: 99%

Section: Ho 2 +Oh=h 2 O+o 2 (R8)mentioning

confidence: 99%

Section: Update On Ho 2 + Oh = H 2 O + O 2 Reaction Rate Correlationmentioning

confidence: 99%

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Chemical Kinetics in Support of Syngas Turbine Combustion

Dryer¹

2007

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“…The time-dependent decay profile was fitted with a 23-step mechanism by varying the rate constants of •OH + NO 2 ↔ HO 2 • + NO and R1. They recommended k 1 = 3×10 13 cm3/mol-s as a compromise of 4×10 13 cm 3 /mol-s over the temperature range of 1237 to 1554 K and the previous data [19][21] [24] in the range of (1-6)×10…”

Section: Reaction Kinetics Of Ho 2 + Ohmentioning

confidence: 99%

Development of Comprehensive Detailed and Reduced Reaction Mechanisms for Syngas and Hydrogen Combustion

Sung¹,

Wang²,

Violi³

2009

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The collaborative research initiative culminated in amassing a substantial combustion database of experimental results for dry and moist mixtures of syngas and hydrogen (SGH), including autoignition times using a rapid compression machine as well as laminar flame speeds using a counterflow twin-flame configuration. These experimental data provided the basis for assessment of the kinetics of SGH combustion at elevated pressures using global uncertainty analysis methods. A review of the fundamental combustion characteristics of H 2 /CO mixtures, with emphasis on ignition and flame propagation at high pressures was also conducted to understand the state of the art in SGH combustion. Investigation of the reaction kinetics of CO+HO 2 • → CO 2 + •OH and HO 2 +OH → H 2 O+O 2 by ab initio calculations and master equation modeling was further carried out in order to look into the discrepancies between the experimental data and the results predicted by the mechanisms. 4 Table of EXECUTIVE SUMMARYA collaborative research effort that involves researchers from Case Western Reserve University, University of Southern California, and University of Michigan aims to provide experimental database of high fidelity and develop comprehensive and computationally efficient reaction mechanism for facilitating the design of SGH fuel combustors. Using CO, H 2 , H 2 O mixtures simulating SGH fuels, fundamental combustion datasets to be obtained experimentally include flame speeds and ignition delay times, with parametric variations of fuel composition, preheat temperature, and pressure. This critical database is needed for validation of chemical kinetics of syngas combustion and is used in conjunction with computation methods, such as global uncertainty analysis, to assess the performance of the literature reaction mechanisms. The present assessment revealed discrepancies in the existing value of a key reaction, CO+HO 2 • → CO 2 + •OH. Reaction kinetics of this reaction was investigated theoretically and a new rate expression was suggested which corrected the noted disagreement in predictions of the existing mechanisms for syngas combustion.The present study is broken down into the following major projects: i. Extensive experimental data for autoignition of dry syngas mixtures at elevated pressures in a rapid compression machine were obtained. Experiments were done for pressures 15-50 bar and temperatures from 950 to 1100 K. Ignition delays were measured for stoichiometric compositions of CO + H 2 containing between 0 and 80% CO in the total fuel mixture. Contrary to the simulated results, the experimental data showed an unequivocal monotonic increase in ignition delay as the proportion of CO in the mixture was raised. ii. Assessment of the kinetics of syngas combustion at elevated pressures using global uncertainty analysis methods was conducted to trace the reason behind the discrepancy of the experimental data and computed results. iii. Extensive experimental data of flame propagation for moist syngas mixtures at elevated unb...

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Flow reactor studies and kinetic modeling of the H2/O2 reaction

Mueller

Kim

Yetter

et al. 1999

Int. J. Chem. Kinet.

404

159

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Profile measurements of the H 2 /O 2 reaction have been obtained using a variable pressure flow reactor over pressure and temperature ranges of 0.3-15.7 atm and 850-1040 K, respectively. These data span the explosion limit behavior of the system and place significant emphasis on HO 2 and H 2 O 2 kinetics. The explosion limits of dilute H 2 /O 2 /N 2 mixtures extend to higher pressures and temperatures than those previously observed for undiluted H 2 /O 2 mixtures. In addition, the explosion limit data exhibit a marked transition to an extended second limit which runs parallel to the second limit criteria calculated by assuming HO 2 formation to be terminating. The experimental data and modeling results show that the extended second limit remains an important boundary in H 2 /O 2 kinetics. Near this limit, small increases in pressure can result in more than a two order of magnitude reduction in reaction rate. At conditions above the extended second limit, the reaction is characterized by an overall activation energy much higher than in the chain explosive regime.The overall data set, consisting primarily of experimentally measured profiles of H 2 , O 2 , H 2 O, and temperature, further expand the data base used for comprehensive mechanism development for the H 2 /O 2 and CO/H 2 O/O 2 systems. Several rate constants recommended in an earlier reaction mechanism have been modified using recently published rate constant data for H ϩ O 2 (ϩ N 2 ) ϭ HO 2 (ϩ N 2 ), HO 2 ϩ OH ϭ H 2 O ϩ O 2 , and HO 2 ϩ HO 2 ϭ H 2 O 2 ϩ O 2 . When these new rate constants are incorporated into the reaction mechanism, model predictions are in very good agreement with the experimental data.

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Heat release and radical recombination in premixed fuel-lean flames of H2+ O2+ N2. Rate constants for H + OH + M ? H2O + M and HO2+ OH ? H2O + O2

Cited by 44 publications

References 3 publications

Chemical Kinetics in Support of Syngas Turbine Combustion

Chemical Kinetics in Support of Syngas Turbine Combustion

Development of Comprehensive Detailed and Reduced Reaction Mechanisms for Syngas and Hydrogen Combustion

Flow reactor studies and kinetic modeling of the H2/O2 reaction

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