Counterflow flame extinction of ammonia and its blends with hydrogen and C1-C3 hydrocarbons

Alfazazi, Adamu; Es-sebbar, Et-touhami; Zhang, Xiaoyuan; Dally, Bassam B.; Abdullah, Marwan; Younes, Mourad; Sarathy, S. Mani

doi:10.1016/j.jaecs.2022.100099

Cited by 4 publications

(6 citation statements)

References 38 publications

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“…Moreover, these reactions compete with reactions that produce OH, i.e., O 2 + H = OH + O (reaction R1) and NH 2 + NO = NNH + OH (reaction R1449). The findings are consistent with ref . This justifies the lower OH production for the NH 3 flames than the N 2 flames and, thus, the lower extinction limits.…”

Section: Discussionsupporting

confidence: 92%

“…For the chemical effect, the combined effects of NO reburn reactions and branching reactions involving HNO that compete for OH and H radicals highly influence the extinction limits of NH 3 flames. 24 Despite the findings, Ku et al 4 and Choi et al 23 highlighted the vast discrepancies between the measured and predicted extinction strain rates, highlighting our lack of understanding of NH 3 combustion. Indeed, to the best of authors' knowledge, studies on the effect of NH 3 substitution on extinction limits of counterflow diffusion flames are still very limited and the blend components are limited to CH 4 4,22 and hydrogen.…”

Section: Introductionmentioning

confidence: 97%

“…However, Ku et al reported that, for CH 4 –NH 3 counterflow diffusion flames, the reduction in the temperature is not remarkable. For the chemical effect, the combined effects of NO reburn reactions and branching reactions involving HNO that compete for OH and H radicals highly influence the extinction limits of NH 3 flames . Despite the findings, Ku et al and Choi et al highlighted the vast discrepancies between the measured and predicted extinction strain rates, highlighting our lack of understanding of NH 3 combustion.…”

Section: Introductionmentioning

confidence: 99%

“…Past studies showed that adding NH 3 to fuels with high reactivity leads to lower extinction limits of counterflow diffusion flames. ,,, Numerical studies suggested that the reduction is likely due to thermal and chemical effects. ,, For the thermal effect, the maximum flame temperature decreases as the amount of NH 3 increases, reducing the concentration of light radicals and, hence, the overall reactivity . However, Ku et al reported that, for CH 4 –NH 3 counterflow diffusion flames, the reduction in the temperature is not remarkable.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to fuel components, extinction limits are also affected by other boundary conditions, i.e., pressure, reactant temperature, and oxygen content. , Thus, while it has benefits in reducing emissions, exhaust gas recirculation (EGR), which mixes CO 2 -rich exhaust gas with fresh intake air, also affects the extinction limits. Increasing the CO 2 content in the oxidizer reduces extinction limits , as a result of the radiative heat loss, dilution, and chemical effects. , However, past studies have focused on conventional fuels.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Chu,

Scialabba,

Liu

et al. 2023

Energy Fuels

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The global extinction limits of non-premixed nitrogen/ammonia-substituted methane− and ethylene−air counterflow flames were experimentally evaluated. In comparison to nitrogen substitution, ammonia substitution reduced the extinction strain rates more. Measurements of OH* chemiluminescence, of which the intensity correlates with extinction limits, suggest that ammonia substitution reduces OH* production. The effects of transport, thermal and chemical properties on flame extinction of the ammonia-substituted flames were assessed, and it was found that their lower extinction limits were due to reactions that consume radicals, which hinder the chain-branching reactions. To mimic the effect of exhaust gas recirculation on the extinction limits of ammonia-substituted flames, carbon dioxide was added to the oxidizer stream. Lower extinction limits were observed with carbon dioxide addition as a result of thermal and chemical effects. Carbon dioxide addition lowered flame temperatures and, like ammonia substitution, introduced reactions that consume radicals. Nitric oxide (NO) production was quantitatively analyzed by simulations. It was found that, for ammonia flames, NO production was promoted by ammonia oxidation with OH, whereas for carbon dioxide addition, NO production was suppressed by the reduction of OH production.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Chu,

Scialabba,

Liu

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

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Flame stabilization and pollutant emissions of turbulent ammonia and blended ammonia flames: A review of the recent experimental and numerical advances

Ahmed,

Xu,

Bai

et al. 2024

Fuel Communications

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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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Counterflow flame extinction of ammonia and its blends with hydrogen and C1-C3 hydrocarbons

Cited by 4 publications

References 38 publications

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Effects of Ammonia Substitution in the Fuel Stream and Exhaust Gas Recirculation on Extinction Limits of Non-premixed Methane– and Ethylene–Air Counterflow Flames

Flame stabilization and pollutant emissions of turbulent ammonia and blended ammonia flames: A review of the recent experimental and numerical advances

Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures

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