Temperature and concentration measurements in a high-pressure gasifier enabled by cepstral analysis of dual frequency comb spectroscopy

Schroeder, Paul J.; Makowiecki, Amanda S.; Kelley, Madison A.; Cole, Ryan K.; Malarich, Nathan; Wright, Robert J.; Porter, Jason M.; Rieker, Gregory B.

doi:10.1016/j.proci.2020.06.011

Cited by 14 publications

(6 citation statements)

References 25 publications

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“…While much recent experimental research in DCS has focused on broadband coverage [8,17,36,37,39,40], the current study instead focuses more on measurement rate: specifically, microsecond-resolved DCS. This work builds on recent studies by the current authors [22,23], Abbas et al [41], and Draper & Schroeder et al [19,38,42] to explore the use of DCS for microsecondresolved measurements. The fundamental tradeoff between time and spectral resolution was recently explored by Hoghooghi et al in the Rieker group through the use of spectral filtering [42].…”

Section: Applications Of Dcsmentioning

confidence: 80%

“…They intentionally reduced the spectral resolution of their near-IR, fiber-based dual-comb spectrometer (DCS) in order to widen the comb-tooth spacing and increase the time resolution. The same group, in a separate work, also demonstrated combined speciation and thermometry by fitting measurements to modeled near-IR spectra [19].…”

Section: Applications Of Dcsmentioning

confidence: 99%

“…By employing two slightly detuned frequency combs outputting a broad range of light, DCS can resolve hundreds or even thousands of wavenumbers at once at timescales limited only by the interference frequencies between the two combs. The DCS approach is reviewed nicely by Coddington et al [8], and has yielded impressive results to date, especially fiberbased spectrometers in the near infrared (near-IR) [9][10][11][12][13][14][15][16][17][18][19][20][21] and a variety of techniques in the mid-infrared (mid-IR). The more recent development of QCL-based DCS offers high power-per-wavelength and extends coverage into the mid-IR, 'molecular fingerprint' region where many species of interest exhibit fundamental absorption features.…”

Section: Introductionmentioning

confidence: 99%

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Quantum-cascade-laser-based dual-comb thermometry and speciation at high temperatures

Pinkowski

Cassady

Strand

et al. 2020

Meas. Sci. Technol.

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This work presents a methodology for using spectroscopic models to fit absorption-spectrum measurements made by a quantum-cascade-laser-based dual-comb spectrometer (QCL-DCS) for high-temperature kinetics research. A pair of quantum-cascade frequency combs was employed to detect methane’s ν 4 absorption features between 1270 and 1320 cm−1 in high-temperature shock-tube environments and extract methane mole fraction and gas temperature from the results. The methodology was first validated by comparing DCS measurements against modeled methane spectra at room temperature in a static cell, followed by assessing the fitting procedure in shock-heated mixtures of 2% methane in Ar at 1000 K. In both validation experiments, the tradeoffs between time resolution and measurement precision were explored. Measurements were achieved at a 4 µs measurement rate with 5% uncertainty for temperature and 4% uncertainty for mole fraction at 1000 K. Higher accuracy was achieved with longer measurement averaging, e.g. 1.8% uncertainty for temperature at 40 μ s resolution. Finally, the DCS spectral-fitting methodology was demonstrated to capture temperature and methane time-history evolution during the pyrolysis of iso-octane, a primary gasoline reference fuel. Good agreement was observed with kinetic models, and future applications for DCS kinetics research are discussed.

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Section: Applications Of Dcsmentioning

confidence: 80%

Section: Applications Of Dcsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantum-cascade-laser-based dual-comb thermometry and speciation at high temperatures

Pinkowski

Cassady

Strand

et al. 2020

Meas. Sci. Technol.

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“…One approach, dual-comb spectroscopy (DCS), uses two laser frequency combs to provide exceptionally fast broadband spectral measurements. DCS has been used to measure greenhouse gases in open-air paths [9][10][11], temperature in a rapid-compression machine [12], temperature and composition from turbines and gasifiers [13,14], methane nonequilibrium in plasmas [15], reaction kinetics in shock tubes [16,17], and more [7,18]. Most DCS diagnostics today utilize near-infrared, fiber-based spectrometers with good spectral resolution but only millisecond-resolved time resolution, with a notable exception by the Rieker group in Colorado [19].…”

Section: Introductionmentioning

confidence: 99%

Thermometry and speciation for high-temperature and -pressure methane pyrolysis using shock tubes and dual-comb spectroscopy

Pinkowski¹,

Biswas²,

Shao³

et al. 2021

Meas. Sci. Technol.

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Quantum-cascade-laser dual-comb spectroscopy (QCL-DCS) is a promising technology with ultra-fast time resolution capabilities for chemical kinetics, atmospheric gas sensing, and combustion applications. A pair of quantum-cascade frequency combs were used to measure absorbance from methane’s band between 1270 and 1315 cm−1 at high-temperature and -pressure conditions that were generated using a high-pressure shock tube. Results here mark a major improvement over previous QCL-DCS measurements in shock tubes. Improvements came from a unique spectral-filtering strategy to correct for a bimodal power-spectral density of QCL frequency combs and careful optimization of the laser setup and experimental conditions. Our modified QCL-DCS was ultimately used to measure temperature within 2% and methane mole fraction within 5% by fitting HITEMP spectral simulations to spectra recorded at 4 μs temporal resolution. We measure temperature and species time-histories during methane pyrolysis at conditions between 1212–1980 K, and 12–17 atm, all at 4 μs resolution. Good agreement is observed with kinetic models, illustrating the potential of future applications of DCS in kinetics and combustion research.

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“…This temperature inversion approach requires an absorption spectrometer that is capable of measuring many transitions in order to resolve more behavior of the temperature distribution. Broad optical bandwidth lasers with the potential to cover 100+ absorption transitions in combustion environments are becoming increasingly ubiquitous, including spectrometers with supercontinuum sources [13,[19][20][21], Fabry-Perot and external-cavity tunable diodes [22,23], MEMS-VCSEL lasers [17,[24][25][26], and broadband versions of frequency comb spectrometers [27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Resolving nonuniform temperature distributions with single-beam absorption spectroscopy. Part I: Theoretical capabilities and limitations

Malarich,

Rieker

2020

Preprint

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Absorption spectroscopy is traditionally used to determine the average gas temperature and species concentration along the laser line-of-sight by measuring the magnitude of two or more absorption transitions with different temperature dependence. Previous work has shown that the nonlinear temperature dependence of the absorption strength of each transition, set by the lowerstate energy, E", can be used to infer temperature variations along the laser line-of-sight. In principle, measuring more absorption transitions with broader bandwidth light sources improves the ability to resolve temperature variations. Here, we introduce a singular value decomposition framework in order to explore the theoretical limits to resolving temperature distributions with single-beam line-of-sight absorption measurements. We show that in the absence of measurement noise or error, only the first ∼14 well-selected absorption features improve the temperature resolution, and a Tikhonov regularization method improves the accuracy of the temperature inversion, particularly for recovery of the maximum gas temperature along the laser beam. We use inversion simulations to demonstrate that one can resolve a selection of temperature distributions along a laser beam line-of-sight to within 3% for the sample cases analyzed. In part II of this work, we explore the influence of measurement noise and error, and experimentally demonstrate the technique to show that there is benefit to measuring additional absorption transitions under real conditions.

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Temperature and concentration measurements in a high-pressure gasifier enabled by cepstral analysis of dual frequency comb spectroscopy

Cited by 14 publications

References 25 publications

Quantum-cascade-laser-based dual-comb thermometry and speciation at high temperatures

Quantum-cascade-laser-based dual-comb thermometry and speciation at high temperatures

Thermometry and speciation for high-temperature and -pressure methane pyrolysis using shock tubes and dual-comb spectroscopy

Resolving nonuniform temperature distributions with single-beam absorption spectroscopy. Part I: Theoretical capabilities and limitations

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