Atomic oxygen measurements in air and air/fuel nanosecond pulse discharges by two photon laser induced fluorescence

Uddi, Mruthunjaya; Jiang, Naibo; Mintusov, Evgeny; Adamovich, Igor V.; Lempert, Walter R.

doi:10.1016/j.proci.2008.06.049

Cited by 193 publications

(177 citation statements)

References 15 publications

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“…Development of this mechanism has been made possible by measurements of time-resolved temperature, N 2 vibrational temperature, N 2 vibrational level populations, absolute number densities of key atomic and radical species, N, O, NO and OH, and ignition temperature in plane-to-plane and point-to-point nanosecond pulse discharges in air, H 2 -air and hydrocarbon-air mixtures [3][4][5][6][7][8][9][10][11][12][13]. The present kinetic mechanism is intended as a starting point for its further development and validation, and expanding the range of its applicability, as additional experimental results become available.…”

Section: Introductionmentioning

confidence: 99%

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas

Adamovich

Lempert

2015

Phil. Trans. R. Soc. A.

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This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H 2 –air and hydrocarbon–air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N 2 vibrational energy transfer, reactions of excited electronic species of N 2 , O 2 , N and O, and ‘conventional’ chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N 2 vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H 2 –air, CH 4 –air and C 2 H 4 –air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H 2 -mixtures, showing good agreement with the data. The model predictions for OH number density in lean C 3 H 8 –air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C 3 H 8 –air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane– n -butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H 2 –air, CH 4 –air and C 2 H 4 –air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane–air mixtures demonstrates the need for development of a more accurate ‘conventional’ chemistry mechanism.

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Section: Introductionmentioning

confidence: 99%

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas

Adamovich

Lempert

2015

Phil. Trans. R. Soc. A.

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“…The nonequilibrium combustion is realized with the help of energetic electrons. In general, the temperature (the mean energy) of electrons in a nonequilibrium plasma is much higher than the gas temperature, and chemical reactions in the nonequilibrium plasma is driven by electron impact dissociation and excitation of neutral species [16][17][18]. In the case of combustion chemistry, for example, the production of OH radicals [19,20] is expected due to electron impact dissociation of H 2 O.…”

Section: Introductionmentioning

confidence: 99%

Transition from equilibrium to nonequilibrium combustion of premixed burner flame by microwave irradiation

Sasaki¹,

Sueoka²

2012

J. Phys. D: Appl. Phys.

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Abstract.We found that the burning velocity in premixed burner flame was enhanced by heated electrons in the flame. The electron heating was realized by irradiating microwave power onto the flame, and was confirmed by observing optical emission intensity of molecular nitrogen at the second positive system. Since the increase of the observed gas temperature was negligible, the enhancement of the burning velocity can be attributed to the nonequilibrium combustion chemistry which is driven by energetic electrons. We examined the time constants for the transition between equilibrium and nonequilibrium combustion states by irradiating pulsed microwave power. As a result, we found > 2 × 10 4 s −1 for the frequency of electron heating, ∼ 1 × 10 3 s −1 for the loss frequency of heated electrons, and ∼ (0.5 − 1) × 10 3 s −1 for the loss frequencies of OH and CH radicals.

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“…The convective transport enhancement of combustion due to plasma instability and ionic wind has also been extensively studied in [7] and [8][9][10]. However, the kinetic enhancement effects on combustion of plasma-produced ions, radicals, and excited species have not been studied to a large extent, especially at low temperature [1][2][3][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Plasma Assisted Low Temperature Combustion

Lefkowitz

Reuter

et al. 2015

Plasma Chem Plasma Process

146

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This paper presents recent kinetic and flame studies in plasma assisted low temperature combustion. First, the kinetic pathways of plasma chemistry to enhance low temperature fuel oxidation are discussed. The impacts of plasma chemistry on fuel oxidation pathways at low temperature conditions, substantially enhancing ignition and flame stabilization, are analyzed base on the ignition and extinction S-curve. Secondly, plasma assisted low temperature ignition, direct ignition to flame transition, diffusion cool flames, and premixed cool flames are demonstrated experimentally by using dimethyl ether and n-heptane as fuels. The results show that non-equilibrium plasma is an effective way to accelerate low temperature ignition and fuel oxidation, thus enabling the establishment of stable cool flames at atmospheric pressure. Finally, the experiments from both a nonequilibrium plasma reactor and a photolysis reactor are discussed, in which the direct measurements of intermediate species during the low temperature oxidations of methane/ methanol and ethylene are performed, allowing the investigation of modified kinetic pathways by plasma-combustion chemistry interactions. Finally, the validity of kinetic mechanisms for plasma assisted low temperature combustion is investigated. Technical challenges for future research in plasma assisted low temperature combustion are then summarized.

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Atomic oxygen measurements in air and air/fuel nanosecond pulse discharges by two photon laser induced fluorescence

Cited by 193 publications

References 15 publications

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas

Transition from equilibrium to nonequilibrium combustion of premixed burner flame by microwave irradiation

Plasma Assisted Low Temperature Combustion

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