On the low-temperature plasma discharge in methane/air diffusion flames

Zare, Saeid; Lo, Hao Wei; Roy, Shrabanti; Askari, Omid

doi:10.1016/j.energy.2020.117185

Cited by 18 publications

(6 citation statements)

References 62 publications

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“…Proper Orthogonal Decomposition of high-speed acquisitions was implemented for a modal Spatio-temporal characterization of the flame, more details are in [16] and [17]. Briefly, the POD extracts an orthogonal basis of eigenvalues from the generic flow data field decoupling the spatial and temporal contributions, that is 𝑔(𝑥; 𝑡) = 𝛴 𝑖 𝑔 𝑖 (𝑥; 𝑡) = 𝛴 𝑖 𝑎 𝑖 (𝑡) 𝜑 𝑖 (𝑥) (6) where the i th temporal eigenfunction represents the i th spatial eigenfunction, and denotes the generic spatial coordinates. The former collects information about the dynamics of the modal coherent structures, the latter consists of a picture of the flow able to capture the scales and shapes of the modal coherent structures.…”

Section: Chemiluminescence Imagingmentioning

confidence: 99%

“…Recently, different plasma generated techniques have been used to improve the flame stabilization and LBO limits such as Zare et. al [6] performed an experimental investigation on lowtemperature plasma introduced in methane/air flames using a coaxial shear injector coupled with a nanosecond pulse generator. It was noticed that ignition characteristics, flame stability, and LBO limits were enhanced.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Flame Behavior and Blowout Limits at Different Air Preheating Temperatures in Plasma Assisted Stabilized Combustor

Giorgi

Mehdi

Bonuso

et al. 2022

Volume 3B: Combustion, Fuels, and Emissions

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This study investigates the flame characterization near to lean blowout (LBO) limits at different pre-heating temperatures in lifted swirl methane-air plasma discharge stabilized flame. The combustor was equipped with a needle-ring type plasma actuator driven by a sinusoidal generator at 20 kHz directly coupled with methane-air premixed flame close to the injector exit. The needle electrode connected with high voltage (HV) and the nozzle acted as a grounded electrode. The electrical characterizations of combustion characteristics and LBO measurements have been carried out at different plasma power, air preheating temperatures, and air mass flow rates. Flame shape and intensity in the flame area have been analyzed based on the images acquired by using a high-resolution camera. Acoustic measurements were performed using high sensitivity microphone. Furthermore, post-processing of the microphone data involved the application of Fast Fourier Transform (FFT) and the wavelet decomposition to identify and characterize any periodic phenomena present in the system. It has been perceived that when the plasma is on, LBO limits were extended significantly. The maximum reduction of equivalence ratio at LBO was noticed in terms of percentage (79.4%) at 40% voltage amplitude, T = 373 K, and ma = 6 m3/h. Proper orthogonal decomposition was implemented on the high-speed chemiluminescence images and the frequency analysis of the time coefficients of the modes of the POD permits the identification of the dominant frequency ranges in the different operating conditions. The results were in good agreement with the findings of the FFT and Wavelet analysis on the microphone measured signals.

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Section: Chemiluminescence Imagingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of Flame Behavior and Blowout Limits at Different Air Preheating Temperatures in Plasma Assisted Stabilized Combustor

Giorgi

Mehdi

Bonuso

et al. 2022

Volume 3B: Combustion, Fuels, and Emissions

View full text Add to dashboard Cite

show abstract

“…In addition, several research programs studied the influence of an electrical discharge on an already existing flame. [13][14][15][16] Lately, the interest in non-equilibrium plasmas has increased. In equilibrium plasmas the electron and heavy particles temperatures are in equilibrium, and ignition is initiated by the high temperature.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of plasma assisted ignition by multi-voltage pulse discharges: A theoretical study

Druker,

Goldwine,

Greenberg

et al. 2024

International Journal of Engine Research

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Currently, compression ignition engine technology is becoming less competitive compared to spark ignition engine technology due to emission standards. Lean combustion strategies are preferable for spark ignition engines, but they require enhanced ignition strategies compared to current stoichiometric spark ignition engines. In this paper, we lay physical foundations for such enhanced ignition strategies that can support lean combustion strategies in spark ignition engines. In this theoretical study, we conduct a preliminary foray into the possibility of controlling the species composition of a cold-plasma kernel as a precursor for an ignition process. We consider a multi-pulse electric source system coupled to a DBD (Dielectric Barrier Discharge) electrode immersed in a dry air medium. The coupled system is designed such that the medium in the electrodes’ gap is subjected to a pulse structure which is composed of a peak voltage followed by a secondary low-voltage pulse. Use is made of a comprehensive mathematical model that includes the electric field, potential and current, with the relevant conservation equations for 24 species and 168 kinetic reactions, while considering different energy modes (rotational, vibrational, electronic excitation, dissociation, and ionization) within the electrodes’ gap. The model was validated against independent published results, and was used to understand the mechanism of energy conversion to species that play a central role in terms of the ultimate ignition dynamics. Various pulse repetition frequencies and different pulse constructions were considered. Special attention was given to the amount of deposited energy, and to the energy channeled to known ignition supportive modes and species. The present results show that the energy deposition can be divided into two main stages which are characterized by high and low voltage levels, respectively. We propose that for more successful ignition, the amount of energy deposition during the second (low voltage) stage should be higher than that during the first (high voltage) stage. During the second stage, the deposition of energy into specific modes can be fine-tuned by setting appropriate voltage levels. Based on these findings, we demonstrate how control of the sequence of voltage pulses can further increase enhancement of ignition and combustion promoting processes.

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“…In this context, we review two types of plasma (i.e. thermal and nonthermal) and a few common sources of ignition such as laser, spark discharge [14,15], nanosecond discharge [16,17], and dielectric barrier discharge (DBD).…”

Section: Introductionmentioning

confidence: 99%

On the ignition kernel formation and propagation: an experimental and modeling approach

Shaffer

Luna

Wang

et al. 2023

J. Phys. D: Appl. Phys.

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The next generation of advanced combustion devices is being developed to operate under ultra-high-pressure conditions. However, under such extreme conditions, flame tends to become unstable and measurement of fundamental properties such as the laminar flame speed becomes challenging. One potential method to resolve this issue is measuring the ignition-affected region during spherically expanding flame (SEF) experiments. Stable flame propagation allows for improved flame measurement, however, the experimentally observed kernel propagation is a function of both inflammation and ignition plasma. Therefore, the goal of the present study is to better understand the plasma formation and propagation during the ignition process. The thermal effect of the plasma is experimentally observed using high-speed Schlieren imaging. The energy dissipated within the plasma is measured electronically and used as an input to numerical modeling. The measured kernel propagation rate is used to assess the accuracy of the model as presented for dry air at 1,3, and 5 atm as well as in CH4-N2 mixtures at 1 atm. The voltage-drop (as the non-thermal loss) is measured to be approximately 330± 5 V (dry air at 1atm) for glow plasma with a large dependency on pressure, gas composition, electrode surface quality, electrode geometry, electrode shape, and current density. The same loss within the arc plasma is measured to be 15± 5 V, however the arc phase loss which agrees with arc propagation is significantly higher (~45 V) which suggest additional unaccounted for phenomena occurring during the arc phase. With these losses, the modeling results are shown to predict the final kernel radius within 10-20% of the observed kernel size. The difference found between the modeling and experimental results is determined to be a result of assuming that the primary loss mechanism (voltage drop across sheath formation) remains constant for the duration of glow discharge.

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On the low-temperature plasma discharge in methane/air diffusion flames

Cited by 18 publications

References 62 publications

Characterization of Flame Behavior and Blowout Limits at Different Air Preheating Temperatures in Plasma Assisted Stabilized Combustor

Characterization of Flame Behavior and Blowout Limits at Different Air Preheating Temperatures in Plasma Assisted Stabilized Combustor

Enhancement of plasma assisted ignition by multi-voltage pulse discharges: A theoretical study

On the ignition kernel formation and propagation: an experimental and modeling approach

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