Experimental and numerical study of product gas and N2O emission characteristics of ammonia/hydrogen/air premixed laminar flames stabilized in a stagnation flow

Hayakawa, Akihiro; Hayashi, Masao; Ковалева, М. А.; Gotama, Gabriel Jeremy; Okafor, Ekenechukwu C.; Colson, Sophie; Mashruk, Syed; Valera‐Medina, Agustin; Kudo, Taku; Kobayashi, Haruo

doi:10.1016/j.proci.2022.08.124

Cited by 27 publications

(14 citation statements)

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“…The emission of N 2 O was also observed in a liquid NH 3 spray combustion experiment . The production and reduction mechanisms of N 2 O were discussed in ref , based on the reaction kinetics developed by Nakamura et al, and the production and reduction mechanisms of N 2 O in NH 3 -H 2 -air premixed flames are summarized in Figure . It should be noted that the relative importance of these reactions may differ across various chemical kinetic models.…”

Section: Fundamental Flame Characteristics Of Nh3mentioning

confidence: 81%

“…Figure shows a schematic of the N 2 O profile in the flame region. According to the discussion in ref and based on the reaction kinetics developed by Nakamura et al, important reactions for N 2 O production and reduction from NH 3 -H 2 flames occurs mainly through 3 reactions below: N H + N O ⇄ N 2 O + H N 2 O + H ⇄ N 2 + O H N 2 O false( prefix+ normalM false) ⇄ N 2 + O false( prefix+ normalM false) …”

Section: Fundamental Flame Characteristics Of Nh3mentioning

confidence: 99%

“…The trade-off characteristics between NO, unburnt NH 3 , and H 2 production in rich conditions were also observed in this experiment. Hayakawa et al 74 performed emission measurements for NH 3 -H 2 -air premixed flames at various equivalence ratios. In their study, it was found that a large amount of N 2 O was produced around an equivalence ratio of approximately 0.6, with the concentration reaching several hundred ppm.…”

Section: Emission Characteristicsmentioning

confidence: 99%

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Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Guiberti,

Pezzella,

Hayakawa

et al. 2023

Energy Fuels

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Ammonia is a molecule that has been essential to human activities for centuries. It is widely used as a feedstock for fertilizers, industrial chemicals, and emissions after-treatment systems. The properties of ammonia have led to its interest as a carrier for hydrogen in energy applications. The combustion of ammonia for power and propulsion offers direct applications of this molecule in energy and transportation applications. However, there are significant challenges related to ammonia combustion, including low flammability and potentially high emissions. Blending of ammonia with hydrogen or hydrocarbons offers opportunities to improve combustibility. This mini review discusses challenges related to ammonia combustion and current state-of-the-art approaches to overcoming these challenges with research into chemical kinetics, laminar and turbulent flames, and engine and turbine systems. This paper seeks to introduce and summarize recent results on ammonia combustion by highlighting pertinent aspects of this rich and rapidly increasing body of information.

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Section: Fundamental Flame Characteristics Of Nh3mentioning

confidence: 81%

Section: Fundamental Flame Characteristics Of Nh3mentioning

confidence: 99%

Section: Emission Characteristicsmentioning

confidence: 99%

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Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Guiberti,

Pezzella,

Hayakawa

et al. 2023

Energy Fuels

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“…Similar observations are made when the oxidizer is diluted, as will be discussed in Section . In gas turbines, low concentrations of N 2 O are achieved when there is a sufficient amount of atomic hydrogen available and high temperatures, allowing contributions from thermal dissociation . This implies that the increased N 2 O emissions in dual-fuel ammonia engines , originate from phenomena that occur during ignition interruption, flame extinction, or reactions at low temperatures.…”

Section: Resultsmentioning

confidence: 99%

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NO_x, N₂O, and Soot Formation

Pedersen,

Lewandowski,

Schulze-Netzer

et al. 2023

Energy Fuels

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The combustion of ammonia in internal combustion engines (ICE) releases nitrogen-related exhaust emissions. Numerous studies have shown that the increased formation of nitrous oxide (N 2 O) may offset ammonia's carbon-free advantages, leading to a higher greenhouse gas potential than fossil fuels. Moreover, nitrogen contained in ammonia further promotes an increase in NO x formation. This study aims to expand the understanding of emission formation in dual-fuel ICEs when using ammonia as a fuel. By constant-pressure reactor simulations coupled with detailed reaction kinetics, the concept of equivalence ratio−temperature diagrams was employed to characterize conditions featuring high NO x , N 2 O, and soot concentrations. The diagrams were obtained for pure ammonia, pure n-heptane, and three blends with ammonia energy shares (AES) of 20, 50, and 80%. Our findings strengthen the perception that high concentrations of N 2 O in ICEs are related to incomplete combustion. A higher AES leads to increased N 2 O concentration during the ignition, going from single-digit ppm levels for pure n-heptane to conditions featuring levels 3 orders of magnitude higher for pure ammonia. In fully burned mixtures, N 2 O emissions feature a low fuel dependency and single-digit concentration levels only at low equivalence ratios and high temperatures. Further, varying contributions from the fuel NO, prompt NO, and thermal De-NO x mechanisms were observed with fuel composition; however, the thermal NO contribution led to a fuel-independent behavior for NO x emissions at temperatures above 2600 K. The soot concentration decreases as the carbon content in the fuel decreases. In our configuration, the lowest equivalence ratio at which the 0.1% soot yield limit was observed was 2.20 for pure n-heptane, 2.65 for AES of 20%, 5.05 for 50% AES, and not attained for higher AES. Ultimately, it was found that in fuel-rich regimes and at fully burned conditions, low concentrations of NO x and N 2 O emissions are observed.

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“…With respect to this third constraint, we constrained exit H 2 values to 1.25 times its equilibrium value at the combustor exit temperature (the exact value of this multiple generally has a negligible impact on results). Note that NH 3 and N 2 O levels themselves are in the parts per billion (ppb) level because of rapid decomposition at flame temperatures . Indeed, if NH 3 or N 2 O levels were used as the constraint, it is very possible to have significant levels of unburned fuel in the form of H 2 , while having NH 3 or N 2 O emissions in ppb levels.…”

Section: Theoretical Analysis and Numerical Frameworkmentioning

confidence: 99%

Air Quality Implications of Using Ammonia as a Renewable Fuel: How Low Can NO_x Emissions Go?

Gubbi,

Cole,

Emerson

et al. 2023

ACS Energy Lett.

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In addition to their lifecycle carbon emissions, another important issue with decarbonized energy pathways is their air quality, water, or land use implications. This paper considers the air quality issue for ammonia combustion. When directly combusting ammonia, reactions of its N atom with atmospheric oxygen lead to NO x emissions that are O(103) ppm, 2 orders of magnitude higher than EPA limits or the amount emitted by current natural-gas-fired technologies. In order to provide guidance to policymakers and technologists on what is fundamentally possible, this Perspective analyzes the fundamental minimum NO x emissions that can be produced from ammonia combustion. The analysis shows that it is possible to achieve quite low NO x emission levels of O(10) ppm, but these designs differ markedly from those used in today’s lean, premixed combustion systems.

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Experimental and numerical study of product gas and N2O emission characteristics of ammonia/hydrogen/air premixed laminar flames stabilized in a stagnation flow

Cited by 27 publications

References 23 publications

Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NO_x, N₂O, and Soot Formation

Air Quality Implications of Using Ammonia as a Renewable Fuel: How Low Can NO_x Emissions Go?

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Experimental and numerical study of product gas and N2O emission characteristics of ammonia/hydrogen/air premixed laminar flames stabilized in a stagnation flow

Cited by 27 publications

References 23 publications

Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Mini Review of Ammonia for Power and Propulsion: Advances and Perspectives

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NOx, N2O, and Soot Formation

Air Quality Implications of Using Ammonia as a Renewable Fuel: How Low Can NOx Emissions Go?

Contact Info

Product

Resources

About

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NO_x, N₂O, and Soot Formation

Air Quality Implications of Using Ammonia as a Renewable Fuel: How Low Can NO_x Emissions Go?