Related references
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Article
Energy & Fuels
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Summary: This study aimed to investigate the injection strategy of ammonia/hydrogen dual fuel engine, optimize the engine performance, and find the optimal combination of compression ratio and injection timing. The results showed that delaying the injection timing could reduce power performance but improve NOx emissions, while increasing the compression ratio greatly improved power performance but slightly increased emissions. Under certain combinations, the NOx emissions could meet Tier II or Tier III emission standards.
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Summary: This study investigates the effect of varying ammonia blending hydrogen ratio on the combustion performance of a diesel engine. The results show that a 30% hydrogen blending ratio leads to increased explosion pressure, improved power, reduced fuel consumption, and decreased ammonia escape and soot emissions.
Review
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Lianwei Kang et al.
Summary: This article reviews various methods to enhance NH3 combustion, including oxygen-enriched combustion and plasma-assisted combustion. The combustion velocity and emissions of NH3 blended with other fuels are analyzed, as well as the combustion of NH3 mixed with liquid fuels and NOx emissions of NH3-fueled gas turbines. The study suggests that rich-lean staged combustion is currently the most desirable approach.
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Kacper Kuta et al.
Summary: This study tested a dual fuel CI engine running on a mixture of ammonia and diesel fuel, aiming to utilize the potential of ammonia in diesel engines. By using the port injection strategy for ammonia and direct injection of diesel oil, a set of different ammonia-diesel mixtures were tested. The composition of the fuel and exhaust species changed due to the partial substitution of diesel fuel by ammonia. The study also investigated the possibility of using residual ammonia to activate the selective catalytic reduction (SCR) system in different engine operating points. The numerical model of the SCR system developed in the research was validated by experimental results.
Article
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Akihiro Hayakawa et al.
Summary: To achieve carbon neutrality, the use of ammonia as a fuel for power generation is expected. A binary fuel of ammonia and hydrogen can address the weak flame characteristics of ammonia. A study investigated the product gas characteristics of ammonia/hydrogen/air flames, finding a trade-off between NO and unburnt ammonia under slightly rich conditions. At lean conditions, NO reached a maximum value of 8,700 ppm, larger than that of pure ammonia/air flames. The study also revealed the important reactions for N2O production and reductions, as well as the influence of flame temperature and equivalence ratio.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Review
Thermodynamics
Paivi T. Aakko-Saksa et al.
Summary: The impact of ship emission reductions can be maximized by considering climate, health, and environmental effects simultaneously and using solutions fitting into existing marine engines and infrastructure. Carbon-neutral fuels, including low-carbon and carbon-negative fuels, could resemble current marine fuels and their carbon-neutrality depends on their emissions of greenhouse gases such as CO2, CH4, N2O, and non-gaseous BC emissions. Harmful emissions like NOx, SOx, ammonia, formaldehyde, PM, PN, polyaromatic hydrocarbons (PAHs), and heavy metals need to be removed using fuel, engine, or exhaust aftertreatment technologies. The combination of carbon-neutral drop-in fuels and efficient emission control technologies could enable (near-)zero-emission shipping.
PROGRESS IN ENERGY AND COMBUSTION SCIENCE
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Xiao Cai et al.
Summary: The role of differential diffusion in highly turbulent premixed flames was investigated using NH-PLIF diagnostics. The study found that subunity Lewis number flames have a higher global consumption speed than super-unity Lewis number flames at high Karlovitz number, indicating the significant role of differential diffusion in highly turbulent flames. Although the flame surface density and area ratio are similar for flames with different Lewis numbers, the stretch factor of sub-unity Lewis number flames is significantly larger than that of super-unity cases. The enhanced global consumption speed of sub-unity Lewis number flames is suggested to be attributed to the promotion of local burning rates by the combined effect of differential diffusion and turbulent flame stretch.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Energy & Fuels
Ping Chen et al.
Summary: Through an experiment with high-temperature furnace, XPS testing, and quantum chemical theory calculations, this study explores the N oxidation mechanism in ammonia-coal co-firing. The results show that both temperature and ammonia mixing ratios significantly affect NO formation. The XPS testing confirms the presence of N atoms in the char resulting from ammonia-coal co-firing. Theoretical calculations reveal that amino groups in the system can be oxidized to produce NO, NO2, and HNO via different paths. This work lays a foundation for understanding the N migration and transformation mechanism in ammonia-coal co-firing and provides theoretical support for achieving low nitrogen combustion.
Article
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Zongkuan Liu et al.
Summary: This study applies the pre-chamber turbulent jet ignition (TJI) technology to address the challenges faced by ammonia-based internal combustion engines (ICEs) such as difficult ignition, combustion instability, and reduced engine performance. Two TJI modes based on a self-designed scavenging pre-chamber were proposed and tested in engine experiments. The results showed that the TJI system optimized combustion stability, improved the burning rate, and reduced emissions of the ammonia engine. This study provides valuable insights into achieving zero-carbon emissions with the TJI ammonia engine.
Article
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Yang Wang et al.
Summary: As global efforts to reduce carbon emissions intensify, the development of alternative fuel combustion solutions for engines shows promise. Ammonia and hydrogen fuels have their own advantages and disadvantages, but their mixture demonstrates good compatibility. However, current ammonia-hydrogen mixture combustion faces limitations in spark ignition or compression ignition, particularly in large-bore marine engines. A proposed scheme of igniting ammonia fuel with a hydrogen jet flame effectively achieves normal full-load power output for marine low-speed engines. The jet flame brings the necessary temperature and reactivity atmosphere, especially the high concentration of H radicals, facilitating the establishment of OH and O radicals conditions needed for combustion and promoting early ammonia combustion. Furthermore, by optimizing the ignition timing of the hydrogen jet flame, NOx emissions can meet the tier III standard in some cases. This scheme shows potential for emissions control while offering relatively better power output and engine performance.
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Summary: The present work provides new insight into the NH3-NO interaction under low-temperature conditions. Experimental investigation was conducted on the oxidation process of neat NH3 and NH3 doped with NO in a Jet Stirred Flow Reactor. A detailed kinetic model was developed to capture the reaction kinetics and species profiles. The role of ammonia as a third-body species and NH2 recombination reactions were found to be essential for predicting the formation of NO and H2.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
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Alessandro Stagni et al.
Summary: Unraveling the low-temperature chemistry of ammonia is a challenge in combustion kinetics. This study investigates the H-abstraction reactions from H2NO by O2, NO2, NH2, and HO2. The predicted rate constants deviate significantly from the commonly adopted rates, highlighting the need for further refinement of the kinetic model.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
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Seif Zitouni et al.
Summary: Ammonia shows promise as a hydrogen-energy carrier and carbon-free fuel, but there is limited research on ammonia combustion under turbulent conditions. This study examines the turbulent flame speeds of ammonia/air, ammonia/methane, and ammonia/hydrogen using a spherically expanding flame configuration. The results show that the flame propagation speed of ammonia/air increases exponentially with increasing hydrogen amount, and that the turbulent to laminar flame speed ratio increases with turbulence intensity. Flame morphology and stretch sensitivity analysis indicate that flame curvature remains relatively similar for pure ammonia and ammonia-based mixtures, and the wrinkling ratio increases with both increasing ammonia fraction and turbulent intensity.
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(2023)
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Xinyi Zhou et al.
Summary: The decarbonization of global shipping is crucial in mitigating climate change, and ammonia has been identified as a sustainable and zero-carbon fuel for the maritime industry. Despite existing studies primarily focusing on automotive engines, research on marine low-speed engines is limited. This paper establishes numerical models for a pilot diesel-ignited ammonia dual-fuel engine, utilizing a commercial low-speed marine diesel engine as a prototype. The models are validated with experimental data, and engine performance and emissions are studied and optimized under both premixed and high-pressure spray combustion modes.
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Shangkun Zhou et al.
Summary: The oxidation of neat NH3 and co-oxidation of NH3 with H2/CO/CH4 were investigated experimentally and numerically. Results showed that H2 can promote NH3 reactivity below 950 K, while CO/CH4 can promote it below 1175 K. HO2 radical was found to be an important intermediate for NH3 oxidation. As temperature increased, the oxidation of NH3 was dominated by independent interactions between fuels and H/OH/O radicals. In stoichiometric conditions, NO formation mainly depended on NH radicals, while in lean conditions, it depended on the conversion of NH2 to NO through HNO intermediate.
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Jizhen Zhu et al.
Summary: This study explores the emission reduction potential of NH3/diesel dual-fuel combustion strategy in large marine engines using computational fluid dynamics modeling coupled with chemical kinetics. The results show that NH3 injection has an inhibiting effect on diesel autoignition and the dual-fuel combustion mode exhibits a two-stage heat release shape. The NOx emission decreases with increasing NH3 substitution ratio, while CO2 emission decreases monotonically with increasing NH3 substitution ratio. There is a trade-off relationship between NOx and N2O emissions, and optimizing injection timing can reduce unburned NH3 and N2O emissions.
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Seong-il Kim et al.
Summary: The optimal operating conditions for ammonia co-firing need to be determined through analyzing boiler performance. It was found that ammonia co-firing can decrease radiation and convective heat transfer rates, resulting in changes in flue gas composition and increased moisture loss, leading to decreased plant efficiency.
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Mehrdad Kiani et al.
Summary: This paper studies the non-preheated MILD combustion behavior of landfill/ammonia mixtures and finds that MILD combustion can provide a uniform temperature distribution and lower pollutant emissions. The results also show that the variation of equivalence ratio has a significant impact on temperature structure and pollutant emissions, while CO2 dilution reduces the furnace's temperature but increases NO generation.
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Cristian D. Avila et al.
Summary: This study investigates the performance of a commercial micro gas turbine when fueled by ammonia-methane blends instead of natural gas. The results show that stable operation is possible until the volume fraction of ammonia reaches 0.63. However, emissions of carbon monoxide, unburned hydrocarbon, and NOx increase significantly above a fraction of 0.22, leading to a drop in combustion efficiency and thermal efficiency. The study suggests that hardware modifications are necessary to comply with NOx regulations and reduce N2O emissions.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
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Yasuhisa Ichikawa et al.
Summary: To reduce greenhouse gas emissions from the maritime sector, there is a need for NH3 fueled marine engines. A new NH3 spray combustion concept called NH3 stratified injection has been proposed for large two-stroke marine engines. This concept utilizes a three-layer stratified fuel injection for better combustion support and has been investigated through various experiments.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
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Andras Gyorgy Szanthoffer et al.
Summary: A possible solution to improve ammonia's combustion properties is blending it with other fuels such as hydrogen and syngas. This study collected extensive experimental data on the combustion of neat NH3, NH3/H2, and NH3/syngas fuel mixtures to investigate the chemistry of co-combustion. The performances of various reaction mechanisms were assessed, and the results showed the need for further mechanism development to accurately reproduce the measurements.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Review
Thermodynamics
A. Alnasif et al.
Summary: Ammonia (NH3) has been proposed as a potential fuel for achieving zero carbon emissions, but its suitability and performance for large-scale applications need careful study. Existing chemical reaction mechanisms for modeling these applications are still being developed. This review examines the current mechanisms and their impact on reaction rates, revealing that most mechanisms have limitations in predicting key combustion characteristics of ammonia flames. The prediction performance of different mechanisms varies with operating conditions, mixing ratios, and equivalence ratios.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
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Alka Karan et al.
Summary: The study focuses on testing laminar flame speed data for ammonia combustion at elevated conditions, with a literature review and sensitivity analysis conducted.
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Gabriel J. Gotama et al.
Summary: The study focuses on the chemical kinetics of NH3/H-2/air flames at rich conditions and elevated pressures, validating a new detailed kinetics mechanism that accurately predicts flame speed.
COMBUSTION AND FLAME
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Shixing Wang et al.
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COMBUSTION AND FLAME
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Haiyang Shi et al.
Summary: NH3 MILD combustion can significantly reduce NOx emissions, and the impact of NH3 flow rate and equivalence ratio on NO emissions in NH3 MILD combustion were analyzed in detail.
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Gu Xin et al.
Summary: This experimental study investigates the suppression of heat release rate in a hydrogen-fueled engine through the addition of ammonia. The results show that adding small amounts of ammonia decreases the combustion rate, prolongs flame development and propagation durations, reduces pressure and heat release rate peaks, and increases peak effective pressure and thermal efficiency. However, it also leads to increased nitrogen oxide emissions.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
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Carlos Gervasio Rodriguez et al.
Summary: The environmental impact of shipping is a significant challenge in today's world. Decarbonizing marine fuels is a key priority in achieving climate neutrality. Free-carbon fuels, especially in dual-fuel mode, are of particular interest for marine engines. This study examines the possibilities of ammonia in marine diesel engines and finds that increasing the proportion of ammonia can lead to significant reductions in carbon emissions, but at the same time, it increases nitrogen oxide (NOx) emissions. To address this issue, the study proposes a second ammonia injection during the expansion stroke to further reduce NOx emissions.
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Qingshuang Fan et al.
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COMBUSTION AND FLAME
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Summary: This study investigates the oxidation of ammonia and proposes a chemical kinetic model for ammonia oxidation. The results show that ammonia oxidation is highly reactive under ultralean conditions, with lower temperatures and higher rates of oxidation. However, this reactivity diminishes rapidly with an increase in equivalence ratio, resulting in similar ammonia oxidation characteristics at equivalence ratios of 0.5 and 1.0. The study also analyzes the reaction pathways for different equivalence ratios and oxidation temperatures.
COMBUSTION AND FLAME
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Ping Chen et al.
Summary: This study investigates the mechanism of ammonia promoting NO reduction in coal-fired boilers through experiments and mathematical calculations, revealing that NH3 co-firing synergistically promotes char's reduction of NO and enriches the research on nitrogen migration and transformation mechanisms under co-firing conditions.
COMBUSTION AND FLAME
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Amin Yousefi et al.
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Energy & Fuels
Ryuhei Kanoshima et al.
Summary: The study focused on investigating the laminar burning velocities and Markstein lengths of ammonia/air mixtures under high-temperature and high-pressure conditions, and compared the effects with methane/air mixtures. Results showed that temperature exponent of ammonia flames was larger and had greater impact on reaction rate compared to methane flames, while pressure exponent of ammonia flames was closer to zero.
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Energy & Fuels
Amin Yousefi et al.
Summary: This study investigates the effect of split diesel injection strategy on an ammonia/diesel dual-fuel engine under medium load conditions. Results show that the use of split diesel injection strategy increases the thermal efficiency and reduces the unburned ammonia emissions. Two optimized split diesel injection strategies are suggested to reduce greenhouse gas emissions while improving combustion efficiency, although they result in higher nitrogen oxides emissions.
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Gu Xin et al.
Summary: This study investigates the effect of different volume fractions of added ammonia on the combustion characteristics of hydrogen internal combustion engines. The addition of ammonia changes the combustion characteristics of hydrogen, but has little effect on nitrogen oxide emissions.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
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Amirreza Mohammadpour et al.
Summary: Numerical study of pure ammonia MILD combustion in a furnace reveals that lowering the furnace wall temperature and diluting the inlet air with nitrogen can improve the characteristics of the reaction zone, reduce fuel and oxidizer consumption rates, increase turbulent Reynolds number, and decrease exhaust emissions.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
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Shixing Wang et al.
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Giovanni Battista Ariemma et al.
Summary: Ammonia is considered a valuable energy vector in the shift towards Renewable Energy Sources. This study investigates the combustion characteristics of ammonia/methane blends under MILD Combustion conditions, revealing that the use of blends expands the operational range of the system but leads to higher NOx emissions.
COMBUSTION AND FLAME
(2022)
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Hongchao Dai et al.
Summary: This study presents the accurate laminar burning velocity, turbulent burning velocity, and their correlations for ammonia/methane/air propagating spherical flames. The results indicate that the turbulent burning velocity decreases with the ammonia content, while the normalized turbulent burning velocity increases. It is also found that the turbulent burning velocity of ammonia flame can be expressed using the correlation of Karlovitz and Damkohler numbers.
COMBUSTION AND FLAME
(2022)
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Qiangxiang Wang et al.
Summary: This paper numerically studies the fuel-NO formation characteristics under CH4/NH3 MILD combustion and finds that the initial NH3 concentration has an impact on NO emissions. In a specific reversed flow furnace, there exists a critical value where MILD combustion cannot reduce NO emissions. Under traditional combustion, enhanced NO reduction via CHi reburning and NO2 interconversion routes can lower NO emissions from NH3 doped fuels.
Article
Energy & Fuels
Jingji Zhu et al.
Summary: Co-firing ammonia promotes devolatilization of coal and release of volatiles, affects the conversion of volatiles into soot, and changes the flame radiation properties. In fuel-lean conditions, co-firing ammonia increases the number density and size of soot particles, while in fuel-rich conditions, they decrease.
Article
Energy & Fuels
Ebrahim Nadimi et al.
Summary: This study investigates the use of ammonia as a primary fuel with biodiesel in a dual-fuel mode. The results show that up to 69.4% of the input energy can be provided by ammonia, but increasing the ammonia mass flow rate slightly decreases the brake thermal efficiency. Furthermore, increasing the ammonia load contribution significantly reduces CO2, CO, and HC emissions, but increases NO emissions. Ammonia delays the start of combustion and decreases the combustion duration compared to pure biodiesel operation.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
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Chemistry, Physical
M. H. Dinesh et al.
Summary: This paper investigates the effects of hydrogen blending on internal combustion engine performance under variable compression ratio and different speeds. The results show that increasing compression ratio and hydrogen fraction can improve combustion and fuel efficiency, but it also leads to higher exhaust temperature and increased NOx emissions.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Review
Green & Sustainable Science & Technology
Yang Wang et al.
Summary: The shipping industry has shown unprecedented concern for reducing emissions and pollution, with the International Maritime Organization enacting regulations on ship emissions. The industry has been focusing on the development and application of low-carbon marine fuels, with liquefied natural gas, liquefied petroleum gas, and methanol being mature technologies for ships in the short term, while biodiesel, hydrogen, and ammonia are expected to become the mainstream alternative fuels in the long term. Challenges such as leakage, low calorific value, and storage difficulties exist for these alternative fuels.
SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS
(2022)
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Wubin Weng et al.
Summary: Ammonia has the potential to reduce carbon dioxide emissions in solid fuel combustion. In this study, the participation of alkali and sulfur species in ammonia conversion in a post-flame environment was characterized. The results showed that alkali metals and sulfur significantly affected the conversion and decomposition of ammonia.
COMBUSTION AND FLAME
(2022)
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Sechul Oh et al.
Summary: The full load performance and emission characteristics of a natural gas-ammonia dual fuel engine were investigated in this study. Experimental results showed that the existing fuel supply system could not provide the required brake torque, leading to increased instability and unburned fuel. The introduction of ammonia resulted in dominant fuel NOx emissions.
Article
Energy & Fuels
Seyed Mahmood Mousavi et al.
Summary: This paper examines the behavior of reacting NH3/H2/CH4 mixtures in moderate or intense low oxygen dilution (MILD) condition. It is observed that addition of NH3 to MILD combustion leads to markedly different behaviors compared to that in conventional combustion, affecting flame lift-off and increasing process reactivity. Additionally, NH3 addition in MILD condition does not increase the emission of NO, while slightly decreasing the mass fraction of NO2.
Article
Energy & Fuels
Davide Lanni et al.
Summary: The use of ammonia in energy systems has gained increasing research interest. This study evaluates the performance and operating limits of a downsized SI engine fueled with pure ammonia using a 1D numerical approach, and verifies the reliability of the model using a 3D approach. The results show that the slow combustion speed of ammonia-air mixtures leads to longer combustion durations, but knock phenomena are avoided.
Article
Thermodynamics
Yasuhisa Ichikawa et al.
Summary: A unique liquid NH3 spray combustion concept is proposed for a large two-stroke marine engine, which applies a three-layer stratified fuel injection and effectively ignites and burns NH3, reducing N2O production.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2022)
Article
Thermodynamics
Akihiro Hayakawa et al.
Summary: The product gas characteristics of ammonia/air premixed laminar flames were investigated experimentally and numerically under various equivalence ratios up to elevated pressure conditions. Experimental results showed that the maximum NO mole fraction was about 3,500 ppmv at an equivalence ratio of 0.9 and decreased with increasing equivalence ratio. The study also found that updating reaction models may be necessary for accurate prediction of product gas characteristics of ammonia/air flames.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Ekenechukwu C. Okafor et al.
Summary: The study investigates the influence of wall heat loss on ammonia-air swirling flames, finding that heat loss strongly affects the flames, leading to flame quenching and increased emissions of unburned NH3, while also promoting the extension of fuel-rich stabilization limit.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Krishna Prasad Shrestha et al.
Summary: This study experimentally investigated the laminar flame speeds of ammonia and ammonia-hydrogen blends under different temperature, pressure, and oxygen content conditions, and developed a new kinetic model for predicting the oxidation mechanisms, considering the formation and reduction of nitrogen oxides. The results showed that the laminar flame speed increases with increasing initial temperature, fuel hydrogen content, or oxidizer oxygen content, but decreases with increasing initial pressure. The proposed kinetic model predicts the same trends as experiments and highlights the importance of N2H2 formation under rich conditions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Suphaporn Arunthanayothin et al.
Summary: Experimental and numerical studies investigated the influence of ammonia addition on methane oxidation, showing that NH3 promoted CH4 reactivity at temperatures below 1200K but had less impact at higher temperatures. A kinetic model helped explain the underlying causes of methane reactivity at low temperatures and the significant role of NOx. The reactivity at higher temperatures was mainly governed by H-abstractions on both fuels.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Charles Lhuillier et al.
Summary: The study aims to elucidate the combustion characteristics of ammonia blends under engine-relevant turbulent conditions, finding that the effects of hydrogen or methane enrichment observed in SI engines cannot be fully explained by the measured laminar burning velocities. The combustion regimes studied are at the boundary between thin and broken reaction zones, influenced by flame-turbulence interactions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Xiaoyuan Zhang et al.
Summary: This study investigates the oxidation of ammonia/hydrogen mixtures at intermediate temperatures using experimental and modeling approaches. The results show that hydrogen blending enhances the oxidation reactivity of ammonia, leading to increased OH radical production and accelerated ammonia consumption. Non-monotonous trends in NOx formation are observed at 99% conversion of ammonia, influenced by the competition between dilution and chemical effects of hydrogen addition.
COMBUSTION AND FLAME
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Shangkun Zhou et al.
Summary: Ammonia (NH3) plays a crucial role in large-scale storage and long-distance transportation of renewable energy. Co-firing with syngas and bio-syngas, along with increasing the initial temperature of reactants, are effective methods to enhance the reactivity of NH3 flames. However, current kinetic models lack accuracy in temperature dependence, indicating a need for further research in this area.
COMBUSTION AND FLAME
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D. Pugh et al.
Summary: This study evaluates different fuel delivery concepts and compares the storage/transport characteristics of NH3 with combustion research challenges. Chemiluminescence intensities are used to study changes in flame topology and their impact on emission concentrations. The study thoroughly considers the influence of primary airflow and staged introduction of secondary air on NOx production, as well as the use of reactant humidification for reducing NOx emissions.
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME
(2021)
Review
Energy & Fuels
A. Valera-Medina et al.
Summary: Ammonia as a fuel vector has been gaining interest and efforts are being made to find new methods to reduce carbon emissions. The current need to decarbonize the economy makes ammonia a viable fuel option, with economic implications being significant.
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Green & Sustainable Science & Technology
Meng-Choung Chiong et al.
Summary: The study reviews the performance results and evaluation of alternative fuel engines under low-medium speed operation in the shipping industry. Neat waste plastic oil and tyre pyrolysis oil showed poorer emissions performance than diesel, while blending TPO with biodiesel improved engine performance significantly. Ammonia is a promising candidate due to its carbon-free composition, but technology is needed to address high NOx emissions. Diesel-like fuel derived from waste lubricant oil demonstrated notably better engine performance than fossil diesel.
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
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Green & Sustainable Science & Technology
Joao Sousa Cardoso et al.
Summary: Ammonia and hydrogen are carbon-free fuels with great potential for energy systems. While hydrogen has high expectations for a carbon-free economy, challenges in storage, distribution, and infrastructure delay its full implementation. Ammonia, on the other hand, delivers high energy density with an established infrastructure, making it a sustainable fuel solution. Constraints in using pure ammonia have led to the development of new strategies for application.
JOURNAL OF CLEANER PRODUCTION
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Bowen Mei et al.
Summary: This study investigates laminar flame propagation of partially cracked NH3/air mixtures and analyzes the effects of equivalence ratio, cracking ratio, and pressure on combustion performance. Results show that in the partial fuel cracking strategy, thermal effect plays a minor role while chemical effect is significant for enhanced laminar flame propagation.
COMBUSTION AND FLAME
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Meng-Choung Chiong et al.
Summary: Ammonia has become an attractive alternative fuel for power generation, showing potential in internal combustion engines and gas turbines. Different optimization strategies may be needed for different types of engines, such as increasing hydrogen mass fraction or utilizing multiple fuel injections. Partial premixed combustion has gained considerable interest in gas turbine research for its ability to operate at low equivalence ratios.
ENERGY CONVERSION AND MANAGEMENT
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Pragya Berwal et al.
Summary: Ammonia is being explored as a potential fuel with its 17.6% hydrogen content making it a carbon-free emission option. Various studies on its applications as a fuel are discussed, along with suggestions for overcoming drawbacks such as lower burning velocities and high NOx emissions.
JOURNAL OF THE ENERGY INSTITUTE
(2021)
Review
Energy & Fuels
Hookyung Lee et al.
Summary: With the establishment of an international carbon-neutral framework, interest in reducing greenhouse gas emissions is growing. Ammonia, as a carbon-free fuel and effective hydrogen energy carrier, is gaining traction in various applications, particularly in power generation systems like gas turbines and coal-fired power plants. Research and technology advancements in utilizing ammonia as fuel are gradually progressing.
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Ekenechukwu C. Okafor et al.
Summary: The development of liquid ammonia spray combustion technology has the potential to reduce costs and sizes of gas turbines, but flame stabilization remains a challenge. This study investigated the flame stability and emissions control in liquid ammonia spray combustion for the first time, showing that the cooling effect of liquid ammonia spray enhances flame blowoff. Emissions analysis revealed that two-stage rich-lean combustion can effectively control emissions, but further enhancements in the primary combustion zone are needed.
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