An experimental and modeling study on auto-ignition of ammonia in an RCM with N2O and H2 addition

Liao, Wanxiong; Chu, Zhaohan; Wang, Yiru; Li, Shuiqing; Yang, Bin

doi:10.1016/j.proci.2022.07.264

Cited by 25 publications

(2 citation statements)

References 40 publications

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“…Aganesyan and Nalbandyan reported the effect of NH 3 addition on the first ignition limit for H 2 /O 2 mixtures in a batch reactor. The structure of premixed NH 3 /H 2 /O 2 flames was investigated in a series of papers by Vandooren, − while flame speed measurements are available from several research groups. ,− Also the stability and extinction of flames fueled by NH 3 /H 2 mixtures have been evaluated. − Ignition delay times have been reported from rapid compression machine (RCM) studies at medium temperatures and elevated pressure − and from shock tube work at higher temperatures. − The oxidation behavior of NH 3 /H 2 mixtures have been studied in flow reactors − and recently also in jet-stirred reactors. − …”

Section: Introductionmentioning

confidence: 99%

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

Alzueta,

Mercader,

Cuoci

et al. 2024

Energy Fuels

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Hydrogen-assisted oxidation of ammonia under flow reactor conditions was investigated through experiments and chemical kinetic modeling. Novel experiments, conducted in a tubular laminar flow reactor as a function of the NH 3 /H 2 ratio, stoichiometry, and temperature (725−1475 K), were analyzed along with literature results from tubular and jet-stirred flow reactors. Ignition and oxidation of NH 3 is strongly promoted by the presence of H 2 under all conditions investigated. In general, the behavior is captured well by the kinetic model. With an increasing fraction of H 2 in the fuel mixture, the generation of chain carriers gradually shifts from being controlled by the amine reaction subset to being dominated by the oxidation chemistry of H 2 , which is known more accurately. However, under reducing conditions, the H 2 consumption rate is strongly underpredicted. This shortcoming suggests that the thermochemistry of amine radicals and/or the formation of higher amines need further assessment. The present analysis shows that for lean oxidation of NH 3 /H 2 mixtures in tubular flow reactors, data obtained at higher temperatures, particularly for NO formation, may be strongly affected by the reaction during preheating or by mixing (dependent on reactor design) in the inlet section prior to the isothermal zone. Modeling predictions for the high pressure, medium-temperature ignition conditions in a large diesel engine indicate that NH 3 /H 2 fuel mixtures may still require a cofuel to secure stable ignition.

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Section: Introductionmentioning

confidence: 99%

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

Alzueta,

Mercader,

Cuoci

et al. 2024

Energy Fuels

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show abstract

“…Nonetheless, ammonia combustion is still impeded by challenges such as poor ignition quality, low burning velocity, and high nitrogen oxide (NOx) emissions, necessitating further research to address these issues. For better understanding of the ammonia reaction mechanisms, laser absorption spectroscopy (LAS) has been successfully employed in shock tube experiments [4][5][6] to achieve time-resolved measurements of temperature and species concentration [7][8][9][10]. However, the lack of spatial resolution of LAS has limited its application mostly to uniform or bulk measurement cases, and the demands to study more complex combustion phenomena such as reaction-flow coupling in turbulent flames call for non-intrusive diagnostic techniques with both temporally and spatially resolving capabilities.…”

Section: Introductionmentioning

confidence: 99%

Non-uniform Line-of-Sight Measurements of Nitric Oxide Mid-infrared Faraday Rotation Spectroscopy

Chao,

Zhu,

Song

et al. 2024

Preprint

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Traditional absorption spectroscopy relies on detecting intensity variations along the line-of-sight to gauge average concentration and temperature. While methods like profile fitting and temperature binning offer insights into the non-uniformity of the path, they fall short of accurately capturing the precise spatial distribution with a single line-of-sight measurement. We propose a novel measurement scheme for non-uniformly distributed concentration of nitric oxide along the line-of-sight utilizing a single laser and path, by incorporating Faraday rotation spectroscopy with magnetic fields changing over time and space. We validate the proposed scheme by measuring a path of two regions in series with different NO concentrations and comparing the measurement results with direct absorption spectroscopy of each respective region. The average relative uncertainty in the concentration measurement for each region is estimated to be within 1.5%.

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Comparison of chemical mechanisms for the oxidation of hydrogen/ammonia mixtures based on different evaluation methods

Yuan,

Yang,

Deng

et al. 2024

Int J of Chemical Kinetics

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For net‐zero carbon emissions, hydrogen/ammonia blends have drawn considerable attention for the application in industrial combustion devices. Various chemical mechanisms have been developed to describe the oxidation and combustion of hydrogen/ammonia mixtures at certain conditions. A comprehensive evaluation and comparison of the performance of these mechanisms is thus of high interest, especially in terms of their application for particular computational studies. Thus, this work aims to compare the existing chemical mechanisms in terms of their performance for the combustion of hydrogen/ammonia mixtures over a wide range of experimental conditions. In addition to previous literature studies, the model performance is evaluated by using two different methods for the assessment of prediction accuracy. Besides the conventional measure of point‐wise differences between model and data, the curve‐matching method is also applied, which quantifies the dependence of model response on physical conditions additionally, by comparing the similarity between the curve shapes of the predicted and measured results. Extensive experimental data are taken into account in the model evaluation, including 136 datasets obtained from various facilities in the past 10 years. Nineteen mechanisms are compared, which were published in recent five years. It is revealed that these models give strongly different numerical results for combustion targets, such as laminar burning velocities, ignition delay times, and species concentrations. The chemical mechanisms of Zhang et al. (2021), Han et al. (2023), Mei et al. (2019), Li et al. (2019), and Stagni et al. (2020) show relatively satisfactory performance over the entire investigated domain. Moreover, it is found that the estimated prediction accuracy of chemical mechanisms is highly sensitive to model evaluation methods.

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An experimental and modeling study on auto-ignition of ammonia in an RCM with N2O and H2 addition

Cited by 25 publications

References 40 publications

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

Non-uniform Line-of-Sight Measurements of Nitric Oxide Mid-infrared Faraday Rotation Spectroscopy

Comparison of chemical mechanisms for the oxidation of hydrogen/ammonia mixtures based on different evaluation methods

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