Temperature- and species-dependent quenching of CO B probed by two-photon laser-induced fluorescence using a picosecond laser

Instantaneous two-dimensional measurements of reaction rate, mixture fraction, and temperature are demonstrated in turbulent partially premixed methane/air jet flames. The forward reaction rate of the reaction CO ‫ם‬ OH ⇒ CO 2 ‫ם‬ H is measured by simultaneous OH laser-induced fluorescence (LIF) and two-photon CO LIF. The product of the two LIF signals is shown to be proportional to the reaction rate. Temperature and fuel concentration are measured using polarized and depolarized Rayleigh scattering. A three-scalar technique for determining mixture fraction is investigated using a combination of polarized Rayleigh scattering, fuel concentration, and CO LIF. Measurements of these three quantities are coupled with previous detailed multiscalar point measurements to obtain the most probable value of the mixture fraction at each point in the imaged plane. This technique offers improvements over two-scalar methods, which suffer from decreased sensitivity around the stoichiometric contour and biases in fuel-rich regions due to parent fuel loss. Simultaneous reaction-rate, mixture-fraction, and temperature imaging is demonstrated in laminar (Re ‫ס‬ 1100) and turbulent (Re ‫ס‬ 22,400) CH 4 /air (1/3 by volume) jet flames. The turbulent jet flame is the subject of multiple numerical modeling efforts. A primary objective for developing these imaging diagnostics is to provide measurements of fundamental quantities that are needed to accurately model interactions between turbulent flows and flames.

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“…[21]. Recent measurements of temperature-dependent quenching cross sections of two-photon CO LIF [22] were used to determine CO concentrations.…”

Section: Turbulent Flame Resultsmentioning

confidence: 99%

Reaction-rate, mixture-fraction, and temperature imaging in turbulent methane/air jet flames

Frank¹,

Kaiser²,

Long³

2002

Proceedings of the Combustion Institute

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“…Ongoing work on energy transfer processes [11] and particularly on quenching cross sections for NO [106] and CO [107] will allow for greater accuracy in the measurement of these important regulated pollutants.…”

Section: The Value Of Combined Diagnosticsmentioning

confidence: 99%

Laser diagnostics and their interplay with computations to understand turbulent combustion

Barlow

2007

Proceedings of the Combustion Institute

211

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“…Assuming the quenching cross sections in Eq. (5) are temperature independent over a small temperature range (300 K) for both CO [37] and CO 2 , the normalized PLIF signal will be independent of temperature. This means that the decrease of the LIF signal due to quenching is the same for different temperatures.…”

Section: Resultsmentioning

confidence: 99%

A convenient setup for laser-induced fluorescence imaging of both CO and CO2 during catalytic CO oxidation

et al. 2017

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[2]. The reaction process is well known under ultra-high vacuum (UHV) conditions where gas flows and gas distribution around a sample are often neglected. However, the number of molecules interacting with the catalyst surface increases significantly at elevated pressures, and as a result, a change in the gas composition close to the surface may lead to a change of the surface structure [3,4]. Therefore, it is essential to obtain in-situ knowledge of the gas composition close to an operating catalyst to achieve a better understanding of the gas-surface interaction.Conventional gas analytical tools such as mass spectrometry (MS), gas chromatography (GC), and Fourier transform infrared spectrometry (FTIR) are often used to analyze gases from the outlet of a reactor. These techniques have the benefit of measuring several species simultaneously, but they suffer from a time delay or poor temporal resolution, and are not capable to spatially resolve the gas composition around a sample. Although capillary sampling techniques can provide spatially resolved concentration profiles inside reactors [5], it cannot deliver two-dimensional measurements to follow dynamic changes in the gas phase on a sub-second scale, and the intrusive nature of the probe may introduce errors in data interpretation.As an in-situ and non-invasive gas detection technique with high spatial and temporal resolution, planar laser-induced fluorescence (PLIF) has been widely used in the combustion community for flame studies [6][7][8], but much less applied in the catalyst community [9]. In earlier studies during the 1990s, LIF has been used to study the OH formation close to a Pt catalyst during the H 2 oxidation [10][11][12][13][14], the distribution of OH desorbed from a Pt catalyst during catalytic water formation reaction [15], and the formaldehyde distribution above a platinum plate during catalytic combustion of methanol/air mixtures [16]. However, in the 2000s, there were Abstract In-situ knowledge of the gas composition close to a catalyst is essential for a better understanding of the gas-surface interaction. With planar laser-induced fluorescence (PLIF), the gas distribution around an operating catalyst can be visualized with high spatial and temporal resolution, in a non-intrusive manner. We report on a convenient setup using a nanosecond YAG-Dye laser system together with a broadband mid-infrared optical parametric oscillator (OPO) for imaging both CO and CO 2 over a Pd(100) catalyst during catalytic CO oxidation, compare it to previously used systems, and show examples of its capabilities.

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Temperature- and species-dependent quenching of CO B probed by two-photon laser-induced fluorescence using a picosecond laser

Cited by 57 publications

References 30 publications

Reaction-rate, mixture-fraction, and temperature imaging in turbulent methane/air jet flames

Reaction-rate, mixture-fraction, and temperature imaging in turbulent methane/air jet flames

Laser diagnostics and their interplay with computations to understand turbulent combustion

A convenient setup for laser-induced fluorescence imaging of both CO and CO2 during catalytic CO oxidation

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