Extinction strain rates of premixed ammonia/hydrogen/nitrogen-air counterflow flames

Richter, Marie; Schultheis, R.; Dawson, James; Gruber, Andrea; Dreizler, Andreas; Geyer, D.

doi:10.1016/j.proci.2022.09.011

Cited by 17 publications

(2 citation statements)

References 19 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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“…However, it faces challenges, including storage issues, safety concerns related to abnormal combustion, and incomplete infrastructure for hydrogen refueling stations [9][10][11]. In contrast, ammonia, as a product of nitrogen and hydrogen synthesis, can be liquefied and stored under standard conditions (liquefaction can be achieved at −33 • C under atmospheric pressure or at atmospheric temperature with 0.8~1.0 MPa pressure) [12]. Therefore, ammonia serves as an excellent carrier for hydrogen, offering advantages such as high energy density, ease of liquefaction and transportation.…”

Section: Introductionmentioning

confidence: 99%

Simulation Study on Combustion Performance of Ammonia-Hydrogen Fuel Engines

Zhao,

Gao,

et al. 2024

Energies

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Ammonia is a very promising alternative fuel for internal combustion engines, but there are some disadvantages, such as difficulty in ignition and slow combustion rate when ammonia is used alone. Aiming to address the problem of ammonia combustion difficulty, measures are proposed to improve ammonia combustion by blending hydrogen. A one-dimensional turbocharged ammonia-hydrogen engine simulation model was established, and the combustion model was corrected and verified. Using the verified one-dimensional model, the effects of different ratios of hydrogen to ammonia, different rotational speeds and loads on the combustion performance are investigated. The results show that the ignition delay and combustion duration is shortened with the increase of the hydrogen blending ratio. The appropriate amount of hydrogen blending can improve the brake’s thermal efficiency. With the increase in engine speed, increasing the proportion of hydrogen blending is necessary to ensure reliable ignition. In conclusion, the ammonia-hydrogen fuel engine has good combustion performance, but it is necessary to choose the appropriate hydrogen blending ratio according to the engine’s operating conditions and requirements.

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Stochastic Modeling of Partially Stirred Reactor (PaSR) for the Investigation of the Turbulence-Chemistry Interaction for the Ammonia-Air Combustion

Yu,

Cai,

Chen

2023

Flow Turbulence Combust

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The Partially Stirred Reactor (PaSR) model is carried out for the ammonia-air combustion system by means of stochastic modeling, namely by solving the transport equation for the joint Probability Density Function (PDF). The turbulent mixing is accounted for by the Linear Mean-Square Estimation (LMSE) mixing model. Notwithstanding the simplified nature of the PaSR modeling, the transported-PDF method enables capturing the effect of mixing frequency on the combustion system, especially the NOx emission. Since the chemical source term is in a closed form in the transported-PDF method, it allows us to apply different chemical mechanisms to explore, whether the set of elementary reactions that are identified as important for the prediction of NOx in the PaSR model is sensitive to the choice of chemical mechanisms. Furthermore, the effect of the residence time in the PaSR model has also been studied, and compared with those in the Perfectly Stirred Reactor (PSR) model (infinite large mixing frequency). Moreover, since the ammonia under oxygen enrichment shows some similar combustion behaviors in terms of e.g. laminar burning velocity as the ammonia under hydrogen enrichment, how large the difference of thermo-kinetic states (e.g. temperature and NOx emission) predicted by PaSR models and in laminar premixed flame configuration is also investigated. A further discussion focuses on the effect of thermal radiation, where the radiative heat loss roles in the prediction of NOx for the turbulent simulation is examined. By using the optically thin approximation model, it is shown that the thermal radiation exhibits little effect on the considered combustion systems within a typical turbulent time-scale.

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Extinction strain rates of premixed ammonia/hydrogen/nitrogen-air counterflow flames

Cited by 17 publications

References 19 publications

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

Simulation Study on Combustion Performance of Ammonia-Hydrogen Fuel Engines

Stochastic Modeling of Partially Stirred Reactor (PaSR) for the Investigation of the Turbulence-Chemistry Interaction for the Ammonia-Air Combustion

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