Shock-tube and plug-flow reactor study of the oxidation of fuel-rich CH4/O2 mixtures enhanced with additives

Sen, Fikri; Shu, Bo; Kasper, Tina; Herzler, Jürgen; Welz, Oliver; Fikri, Mustapha; Atakan, Burak; Schulz, Christof

doi:10.1016/j.combustflame.2016.03.030

Cited by 44 publications

(17 citation statements)

References 35 publications

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“…Here, the P(8) transition was used. The overall experimental uncertainties were similar as in the previous study. The temperature uncertainty in this work was 1%, and the overall uncertainty in CO mole fraction is 3%.…”

Section: Resultssupporting

confidence: 84%

“…CO concentrations were measured by absorption across the shock tube using mid‐IR quantum‐cascade lasers. Details of the optical arrangement of the laser absorption system have been described previously . In this work, a cw‐QC laser centered at 2111.54 cm −1 (4735.88 nm) (P(8) transition of the fundamental vibrational band)(Adtech Laser) was applied instead of 2059.91 cm −1 (P(20) transition) (Alpes Laser), which was used in the previous setup due to its larger line strength at temperature lower than 1100 K. A pinhole was installed in front of the laser to prevent back reflection of laser light from the sapphire window of the shock tube into the laser.…”

Section: Experiments and Theorymentioning

confidence: 99%

“…Details of the optical arrangement of the laser absorption system have been described previously . In this work, a cw‐QC laser centered at 2111.54 cm −1 (4735.88 nm) (P(8) transition of the fundamental vibrational band)(Adtech Laser) was applied instead of 2059.91 cm −1 (P(20) transition) (Alpes Laser), which was used in the previous setup due to its larger line strength at temperature lower than 1100 K. A pinhole was installed in front of the laser to prevent back reflection of laser light from the sapphire window of the shock tube into the laser. An integrating sphere (Labsphere) was installed in front of the detector (VIGO system with a 2‐mm diameter) to homogenize the transmitted laser light and eliminate any unwanted oscillations of the signal due to beam‐steering effects.…”

Section: Experiments and Theorymentioning

confidence: 99%

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A Shock Tube and Modeling Study about Anisole Pyrolysis Using Time-Resolved CO Absorption Measurements

Shu

Herzler

Peukert

et al. 2017

Int. J. Chem. Kinet.

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The pyrolysis of anisole (C 6 H 5 OCH 3 ) was studied behind reflected shock waves via highly sensitive absorption measurements of CO concentration using a rotational transition in the fundamental vibrational band near 4.7 µm. Time-resolved CO mole fractions were monitored in shock-heated C 6 H 5 OCH 3 /Ar mixtures between 1000 and 1270 K at 1.3-1.6 bar. The decomposition of C 6 H 5 OCH 3 proceeds exclusively via homolytic dissociation, with reaction rate k 1 , forming methyl (CH 3 ) and phenoxy (C 6 H 5 O) radicals. The subsequent decomposition of C 6 H 5 O by ring rearrangement and bond dissociation yields CO. To determine the rate constant k 2 of C 6 H 5 O decomposition avoiding secondary reactions, allyl phenyl ether (C 6 H 5 OC 3 H 5 ) was used as an alternative source for C 6 H 5 O. Its decomposition was studied between 970 and 1170 K at ß1.4 bar. The potential-energy surface of C 6 H 5 O dissociation has been reevaluated at the G4 level of theory. Rate constants determined from unimolecular rate theory are in good agreement with the present experiments. However, the obtained rates k 2 = 9.1 × 10 13 exp(−220.3 kJ mol −1 /RT)s −1 are significantly higher than those reported before (factor 6, 2, and 1.5 faster than those data reported by Lin and Lin, J. Phys. Chem. 1986, 90, 425-431;Frank et al., 1994; Carstensen and Dean, 2012, respectively). Good agreement was found between the measured CO concentration profiles and simulations based on the mechanism of Nowakowska et al. after substituting k 2 by the value obtained from experiments on C 6 H 5 OC 3 H 5 in this work. The

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Section: Resultssupporting

confidence: 84%

Section: Experiments and Theorymentioning

confidence: 99%

Section: Experiments and Theorymentioning

confidence: 99%

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A Shock Tube and Modeling Study about Anisole Pyrolysis Using Time-Resolved CO Absorption Measurements

Shu

Herzler

Peukert

et al. 2017

Int. J. Chem. Kinet.

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“…Absorption-based diagnostic studies are non-intrusive, provide in-situ measurements (e.g., concentration of individual species including trace species, temperature) and have fast-time response. The combination of shock-heating and non-intrusive laser detection provides a state-of-the-art test platform for high-temperature kinetics of various hydrocarbons and oxygenates [32,[37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Measurements and interpretation of shock tube ignition delay times in highly CO2 diluted mixtures using multiple diagnostics

Pryor

Barak

Köroğlu

et al. 2017

Combustion and Flame

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Common definitions for ignition delay time are often hard to determine due to the issue of bifurcation and other non-idealities that result from high levels of CO 2 addition. Using highspeed camera imagery in comparison with more standard methods (e.g., pressure, emission, and laser absorption spectroscopy) to measure the ignition delay time, the effect of bifurcation has been examined in this study. Experiments were performed at pressures between 0.6 and 1.2 atm for temperatures between 1650 and 2040 K. The equivalence ratio for all experiments was kept at a constant value of 1 with methane as the fuel. The CO 2 mole fraction was varied between a value of X CO2 = 0.00 to 0.895. The ignition delay time was determined from three different measurements at the sidewall: broadband chemiluminescent emission captured via a photodetector, CH 4 concentrations determined using a distributed feedback interband cascade laser centered at 3403.4 nm, and pressure recorded via a dynamic Kistler type transducer. All methods for the ignition delay time were compared to high-speed camera images taken of the axial cross-section during combustion. Methane time-histories and the methane decay times were also measured using the laser. It was determined that the flame could be correlated to the ignition delay time measured at the side wall but that the flame as captured by the camera was not homogeneous as assumed in typical shock tube experiments. The bifurcation of the shock wave resulted in smaller flames with large boundary layers and that the flame could be as small as 30% of the cross-sectional area of the shock tube at the highest levels of CO 2 dilution. Comparisons between the camera images and the different ignition delay time methods show that care must be taken in interpreting traditional ignition delay data for experiments with large

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“…Understanding the relevant chemistry is a cornerstone in the choice of fuels and energy storage media that may be useful for systems integration. Recent work on on-board fuel reforming [137], on using IC engines in polygeneration processes for the production of higher-value chemicals [138,139], as an approach for energy conversion and storage [139,140], as well as on co-generation of power and syngas [141] might serve as indications for future opportunities.…”

Section: Perspectivesmentioning

confidence: 99%

A new era for combustion research

Kohse‐Höinghaus

2019

Pure and Applied Chemistry

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Current topics in combustion chemistry include aspects of a changing fuel spectrum with a focus on reducing emissions and increasing efficiency. This article is intended to provide an overview of selected recent work in combustion chemistry, especially addressing reaction pathways from fuel decomposition to emissions. The role of the molecular fuel structure will be emphasized for the formation of certain regulated and unregulated species from individual fuels and their mixtures, exemplarily including fuel compounds such as alkanes, alkenes, ethers, alcohols, ketones, esters, and furan derivatives. Depending on the combustion conditions, different temperature regimes are important and can lead to different reaction classes. Laboratory reactors and flames are prime sources and targets from which such detailed chemical information can be obtained and verified with a number of advanced diagnostic techniques, often supported by theoretical work and simulation with combustion models developed to transfer relevant details of chemical mechanisms into practical applications. Regarding the need for cleaner combustion processes, some related background and perspectives will be provided regarding the context for future chemistry research in combustion energy science.

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Shock-tube and plug-flow reactor study of the oxidation of fuel-rich CH4/O2 mixtures enhanced with additives

Cited by 44 publications

References 35 publications

A Shock Tube and Modeling Study about Anisole Pyrolysis Using Time-Resolved CO Absorption Measurements

A Shock Tube and Modeling Study about Anisole Pyrolysis Using Time-Resolved CO Absorption Measurements

Measurements and interpretation of shock tube ignition delay times in highly CO2 diluted mixtures using multiple diagnostics

A new era for combustion research

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