Measurements of temperature and hydroxyl radical generation/decay in lean fuel–air mixtures excited by a repetitively pulsed nanosecond discharge

Yin, Zhiyao; Montello, Aaron; Carter, Campbell D.; Lempert, Walter R.; Adamovich, Igor V.

doi:10.1016/j.combustflame.2013.03.015

Cited by 83 publications

(115 citation statements)

References 33 publications

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“…These images illustrate that the plasma remains diffuse and filament-free at these conditions. Figure 11 compares experimental [8] and predicted absolute OH number density and temperature measured on the discharge centreline in lean H 2 -air mixtures (equivalence ratio φ = 0.015-0.12), initially at T = 500 K and P = 100 Torr, after a repetitively pulsed nanosecond discharge (50-pulse burst, pulse repetition rate 10 kHz). In the calculations, the coupled discharge power waveform used was the one shown in figure 2, scaled to account for estimated energy loss in the corona discharge outside the test section (energy coupled to the plasma of 1.0 mJ per pulse), i.e.…”

Section: Resultsmentioning

confidence: 99%

“…(b) Nanosecond pulse discharges in fuel-air mixtures Figure 10 shows intensified charge-coupled device (ICCD) images of plane-to-plane, double dielectric barrier discharges in air, H 2 -air (φ = 0.3), and C 2 H 4 -air (φ = 0.3) preheated to T 0 = 500 K, taken through the window in the end of a rectangular quartz channel where the plasma was sustained [8]. These images illustrate that the plasma remains diffuse and filament-free at these conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Discharge pulses are indicated schematically in the plot. [8] and predicted N 2 vibrational temperature in dry air, initially at T = 500 K and P = 100 Torr, after a repetitively pulsed nanosecond discharge burst in plane-to-plane geometry (50-pulse and 100-pulse bursts, pulse repetition rate 10 kHz). (Online version in colour.…”

Section: Resultsmentioning

confidence: 99%

“…The list of air and fuel-air plasma processes in tables 1 and 2 has been updated compared with our previous publications [3][4][5][6][7][8], primarily to account for N 2 vibrational energy transfer in high specific energy loading nanosecond pulse discharges [9][10][11][12], reactions of excited metastable atoms, N( 2 P, 2 D) and O( 1 D, 1 S), and to incorporate the effect of multiple excited electronic states of nitrogen, N * 2 , on NO formation during reactive quenching by O atoms, N * 2 + O → NO + N [10,11]. In the updated fuel-air plasma mechanism, cross sections of electron impact excitation processes are taken from Bolsig+ database LXcat [14].…”

Section: Kinetic Modelmentioning

confidence: 99%

“…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%

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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: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Kinetic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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A review on plasma combustion of fuel in internal combustion engines

et al. 2017

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Summary In recent years, new ways of improving the combustion efficiency of fuel during gas turbine operations have been developed. The most significant has been the application of plasma technology for the combustion of fuel in gas turbine operations. Plasma is formed when gas is exposed to either high temperature or high‐voltage electricity. This technology is very promising and has proven to enhance the performance of gas turbines and reduce toxic emissions. Recent studies have shown the use of different types of plasma applications in gas turbine operations such as plasma torch, filamentary discharge, and nanosecond pulse discharge, whose results show that plasma technology has great potential in improving flame stabilization, the fuel/air mixing ratio, and flash point values of these fuels. These findings and advances have further provided new opportunities in the development of efficient plasma discharges for practical uses in plasma combustion of fuel for gas turbine operations. This article is a comprehensive overview of the advances and blind spots in the knowledge of plasma combustion of fuel during internal combustion engine operations. This review also focuses on applications, methods, and experimental results in plasma combustion of fuel in gas turbines.

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MBMS study on plasma‐assisted low‐temperature oxidation of n‐heptane and iso‐octane in a flow reactor

Liao

Chen

Liu

et al. 2020

Int J of Chemical Kinetics

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Nonequilibrium plasma has a great potential in the lean combustion of gasoline engines. However, fundamental studies on plasma‐assisted combustion on gasoline components are limited. In the present study, Low‐temperature oxidation behaviors for n‐heptane and iso‐octane in a plasma flow reactor were investigated. Species measurements were performed at room temperature and low pressure of 40 mbar using the electron ionization molecular‐beam mass spectrometry (EI‐MBMS). A total of 72 and 57 species were quantified in n‐heptane and iso‐octane oxidation, respectively. Based on measured species data, reaction networks of n‐heptane and iso‐octane in the plasma system were discussed. Particularly, some typical low‐temperature intermediates, such as cyclic ethers, diones, and ketohydroperoxides, were observed, suggesting the applicability of the classical low‐temperature reaction scheme in the plasma system of large hydrocarbons. The results indicate that the major role of plasma discharge on the low‐temperature oxidation of large hydrocarbons is either to breakdown large fuel molecules or to accelerate the chain initiation reactions. We also investigated the parametric effects of voltage, frequency, and residence time on the species pools, and found that the increase of these parameters leads to higher production of intermediates. The whole system reactivity was most sensitive to the plasma voltage. The difference between plasma frequency and residence time on the species formation was found. Moreover, some highly temperature‐sensitive reactions, such as the RO2 → QOOH, proceed at very low temperatures (around 340 K) in the plasma system, which was potentially attributed to the additional energy from plasma‐generated species.

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Measurements of temperature and hydroxyl radical generation/decay in lean fuel–air mixtures excited by a repetitively pulsed nanosecond discharge

Cited by 83 publications

References 33 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

A review on plasma combustion of fuel in internal combustion engines

MBMS study on plasma‐assisted low‐temperature oxidation of n‐heptane and iso‐octane in a flow reactor

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