Study of mechanism of ammonia decomposition and oxidation: From NOx reduction to ammonia auto-ignition problem

Bykov, Viatcheslav; Stein, Marcus; Maas, Ulrich

doi:10.1016/j.proci.2022.07.048

Cited by 6 publications

(5 citation statements)

References 25 publications

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“…This caused the in-cylinder combustion temperature, particularly in the overly rich mixture region, to increase considerably and increase NO x formation. Another reason could be that ammonia has a nitrogen atom in its structure, and thereby combustion of ammonia produces nitrogen oxide emissions. , The ammonia fuels NO x in the oxidation through the reaction radicals formed by H-abstraction (NH 2 , NH, and N) reactions with O radicals to produce NO …”

Section: Resultsmentioning

confidence: 99%

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Investigation on Ammonia–Biodiesel Fueled RCCI Combustion Engine Using a Split Injection Strategy

Ramachandran,

Krishnaiah,

Perumal Venkatesan

et al. 2023

ACS Omega

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Advanced combustion concepts in compression ignition are emerging as one of the most promising solutions to reduce nitrogen oxides (NO x ) and particle emissions without sacrificing fuel efficiency. Among many advanced combustion concepts, reactive controlled compression ignition (RCCI) can achieve a wider working range. In this study, to implement RCCI operation, ammonia gas is introduced through the manifold as a low-reactive fuel, and biodiesel is injected directly as a high-reactivity fuel with a 40:60 energy ratio. The effect of biodiesel split ratio in a split injection strategy (pre- and main injections) is examined under varied load conditions, and the results are compared with ammonia/biodiesel single injection. Results indicate that the use of the 45% biodiesel split ratio at full load boosts the peak in-cylinder pressure and heat release rate and shifts the peak occurrence toward the top dead center (TDC). An increase in brake thermal efficiency (BTE) to 36.22% and reduced brake specific energy consumption (BSEC) to 8.75 MJ/kWh are 12.33% higher and 19.31% lower than ammonia/biodiesel single injection. Emissions of HC, CO, and smoke opacity were reduced to 50 ppm, 0.098% vol, and 15.6%, which are 34.21, 39.13, and 33.89% lower, while the emission of NO x was increased to 615 ppm, which is 36.06% higher than the single-injection ammonia/biodiesel RCCI combustion.

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Section: Resultsmentioning

confidence: 99%

“…Another reason could be that ammonia has a nitrogen atom in its structure, and thereby combustion of ammonia produces nitrogen oxide emissions. 52 , 53 The ammonia fuels NO x in the oxidation through the reaction radicals formed by H-abstraction (NH 2 , NH, and N) reactions with O radicals to produce NO. 54 …”

Section: Resultsmentioning

confidence: 99%

Investigation on Ammonia–Biodiesel Fueled RCCI Combustion Engine Using a Split Injection Strategy

Ramachandran,

Krishnaiah,

Perumal Venkatesan

et al. 2023

ACS Omega

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“…Flame combustion, on the other hand, is a simple, direct, and rough heating method with high combustion temperature but low combustion efficiency. Current research on NH 3 flame combustion primarily concentrates on the stability of NH 3 combustion (including pure NH 3 combustion [55,160,161], mixed combustion [162][163][164], and auxiliary combustion [31,165]) and reducing NO x emissions [166][167][168][169]. The chemical reaction process in direct NH 3 FCs and IA-PEMFCs is illustrated in Figure 22.…”

Section: Research Routes Of Ia-pemfcsmentioning

confidence: 99%

Application of NH3 Fuel in Power Equipment and Its Impact on NOx Emissions

Hu,

Liu,

et al. 2024

Energies

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Due to high greenhouse gas emissions, countries worldwide are stepping up their emission reduction efforts, and the global demand for new, carbon-free fuels is growing. Ammonia (NH3) fuels are popular due to their high production volume, high energy efficiency, ease of storage and transportation, and increased application in power equipment. However, their physical characteristics (e.g., unstable combustion, slow flame speed, and difficult ignition) limit their use in power equipment. Based on the structural properties of the power equipment, NH3 fuel application and emissions characteristics were analyzed in detail. Combustion of NH3 fuels and reduction measures for NOx emissions (spark plug ignition, compression ignition, and gas turbines) were analyzed from various aspects of operating conditions (e.g., mixed fuel, fuel-to-exhaust ratio, and equivalence ratio), structure and strategy (e.g., number of spark plugs, compression ratio (CR), fuel injection, and ignition mode), and auxiliary combustion techniques (e.g., preheating, humidification, exhaust gas recirculation, and secondary air supply). The performance of various NH3 fuel cell (FC) types was analyzed, with a focus on the maximum power achievable for different electrolyte systems. Additionally, the application and NOx emissions of indirect NH3 FCs were evaluated under flame and catalytic combustion conditions. The system efficiency of providing heat sources by burning pure NH3, anode tail gas, and NH3 decomposition gas was also compared. Based on a comprehensive literature review, the key factors influencing the performance and emissions of NH3-powered equipment were identified. The challenges and limitations of NH3-powered equipment were summarized, and potential strategies for improving efficiency and reducing emissions were proposed. These findings provide valuable insights for the future development and application of NH3 FCs.

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“…In our previous papers, different algorithms including global analysis [7], local analysis [12], and the combination of both [15] have been proposed and validated for different reaction systems. The interested readers are referred to the references mentioned.…”

Section: Generation Of the Gql Linearization Matrixmentioning

confidence: 99%

Autoignition Problem in Homogeneous Combustion Systems: GQL versus QSSA Combined with DRG

Yu,

Shashidharan,

et al. 2023

Modelling

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The global quasi-linearization (GQL) is used as a method to study and to reduce the complexity of mathematical models of mechanisms of chemical kinetics. Similar to standard methodologies, such as the quasi-steady-state assumption (QSSA), the GQL method defines the fast and slow invariant subspaces and uses slow manifolds to gain a reduced representation. It does not require empirical inputs and is based on the eigenvalue and eigenvector decomposition of a linear map approximating the nonlinear vector field of the original system. In the present work, the GQL-based slow/fast decomposition is applied for different combustion systems. The results are compared with the standard QSSA approach. For this, an implicit implementation strategy described by differential algebraic equations (DAEs) systems is suggested and used, which allows for treating both approaches within the same computational framework. Hydrogen–air (with 9 species) and ethanol–air (with 57 species) combustion systems are considered representative examples to illustrate and verify the GQL. The results show that 4D GQL for hydrogen–air and 14D GQL ethanol–air slow manifolds outperform the standard QSSA approach based on a DAE-based reduced computation model.

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Study of mechanism of ammonia decomposition and oxidation: From NOx reduction to ammonia auto-ignition problem

Cited by 6 publications

References 25 publications

Investigation on Ammonia–Biodiesel Fueled RCCI Combustion Engine Using a Split Injection Strategy

Investigation on Ammonia–Biodiesel Fueled RCCI Combustion Engine Using a Split Injection Strategy

Application of NH3 Fuel in Power Equipment and Its Impact on NOx Emissions

Autoignition Problem in Homogeneous Combustion Systems: GQL versus QSSA Combined with DRG

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