Search Results (212)

This research considers a preliminary comparative technical evaluation of two micro-gas turbine (MGT) systems in combined heat and power (CHP) mode (100 kWe), aimed at supplying heat to a residential community of 15 average-sized buildings located in Central Europe over a year. Two systems were modelled in Ebsilon 15 software: a natural gas case (benchmark) and an ammonia-fueled case, both based on the same on-design parameters. Off-design simulations evaluated performance over variable ambient temperatures and loads. Idealized, unrecuperated cycles were adopted to isolate the thermodynamic impact of the fuel switch under complete combustion assumption. Under these assumptions, the study shows that the ammonia system produces more electrical energy and less excess heat, yielding marginally higher electrical efficiency and EUF (26.05% and 77.63%) than the natural gas system (24.59% and 77.55%), highlighting ammonia’s utilization potential in such a context. Future research should target validating ammonia combustion and emission profiles across the turbine load range, and updating the thermodynamic model with a recuperator and SCR accounting for realistic pressure losses. Full article

In response to increasingly stringent emission regulations, low-carbon fuels have received significant attention as sustainable energy sources for internal combustion engines. This study investigates four representative low-carbon fuels, methane, methanol, hydrogen, and ammonia, by systematically summarizing their combustion characteristics and emission profiles, along with a review of existing after-treatment technologies tailored to each fuel type. For methane engines, unburned hydrocarbon (UHC) produced during low-temperature combustion exhibits poor oxidation reactivity, necessitating integration of oxidation strategies such as diesel oxidation catalyst (DOC), particulate oxidation catalyst (POC), ozone-assisted oxidation, and zoned catalyst coatings to improve purification efficiency. Methanol combustion under low-temperature conditions tends to produce formaldehyde and other UHCs. Due to the lack of dedicated after-treatment systems, pollutant control currently relies on general-purpose catalysts such as three-way catalyst (TWC), DOC, and POC. Although hydrogen combustion is carbon-free, its high combustion temperature often leads to elevated nitrogen oxide (NO_x) emissions, requiring a combination of optimized hydrogen supply strategies and selective catalytic reduction (SCR)-based denitrification systems. Similarly, while ammonia offers carbon-free combustion and benefits from easier storage and transportation, its practical application is hindered by several challenges, including low ignitability, high toxicity, and notable NO_x emissions compared to conventional fuels. Current exhaust treatment for ammonia-fueled engines primarily depends on SCR, selective catalytic reduction-coated diesel particulate filter (SDPF). Emerging NO_x purification technologies, such as integrated NO_x reduction via hydrogen or ammonia fuel utilization, still face challenges of stability and narrow effective temperatures. Full article

Mathematical modeling and computer visualization of hazardous zones of toxic substance cloud spread that occur during different accidents at industrial enterprises located near residential areas are in high demand to support the operational planning of evacuation measures and accident response. The possible chain-like nature of fires and explosions of containers with toxic substances inside increases the importance of predicting changes in hazardous zone parameters in real time. The objective of this study is to develop algorithms for the development of a mathematical model of a hazardous zone during an explosion and fire at an enterprise. The subject of this study is a software tool created for the visualization of hazardous substance emission zones in real time, superimposed onto a development map to determine potential damage to human health and for the operational planning of evacuation measures. The proposed model takes into account variables such as the air temperature, wind speed and direction, the mass of the substance at each explosion and fire site, etc. C# and Visual Studio 2022 languages and an SQL database were used to create a software tool for visualizing the hazardous area. The testing of the calculation model and software used for the visualization of the hazardous zones of toxic substance cloud spread are presented on the basis of explosion cases involving a railway tank containing ammonia and the combustion of polyvinyl chloride at a chemical industry enterprise. The results confirmed the operability of the software and the prospects of its use in regard to the mitigation of the consequences of human-made accidents. Full article

Due to the unique physicochemical properties of ammonia fuel, any leakages in the engine room will inevitably endanger ship safety. This study focuses on investigating the diffusion behavior of ammonia fuel within the engine room during ship navigation after leakage, aiming to identify hazardous points and implement measures, such as installing air-blowing and extraction devices, to mitigate the risks. To address potential leakage risks in ammonia-fueled ships, a simplified three-dimensional computational model was developed based on ship design drawings and field investigations. ANSYS Fluent software (2024 R2) was employed to simulate ammonia fuel leakage from pipelines and equipment, analyzing the diffusion patterns of leakage at different locations and evaluating the impact of adding air-blowing and extraction devices on leaked fuel in the engine room. The simulation results demonstrate that leakage at point 3 poses the greatest operational hazard, and ammonia fuel leakage during navigation generates combustible gas mixtures within the explosion limit range around the main engine, severely threatening both vessel safety and crew lives. Installing air-blowing and extraction devices in high-risk areas effectively reduces the explosion limit range of ammonia fuel, with air outlet 3 showing optimal mitigation effectiveness against ammonia fuel leakage during ship transportation. Full article

This study investigates the impact of different combustion control strategies on marine engine combustion and emission characteristics at a high ammonia energy ratio. Compared to the strategy of maintaining a constant fuel injection duration, the strategy of keeping the fuel injection pressure constant allows the kinetic energy of diesel to remain at a higher level. This results in an increase in combustion efficiency and indicated the thermal efficiency of the engine, while also reducing CO₂ and soot emissions. However, when the ammonia energy ratio increases to more than 50%, the indicated thermal efficiency starts to decrease along with the increase in the emissions of N₂O and unburned ammonia. To address these issues, one of the potential means is to improve the in-cylinder combustion environment by increasing the in-cylinder gas temperature. This can enhance combustion efficiency and ultimately optimize the performance and emission characteristics of dual-fuel engines, which results in an increase in the combustion efficiency to 98% and indicated thermal efficiency to 54.47% at a relatively high ammonia energy ratio of 60%. Emission results indicate that N₂O emissions decrease from 1099 ppm to 25 ppm, while unburned ammonia emissions drop from 16016 ppm to 100 ppm. Eventually, the greenhouse gas emissions were reduced by about 85.3% in comparison with the baseline case. Full article

This paper analyzes the influence of the number of ignition coils and spark discharge energy on the Coefficient of Variation of Indicated Mean Effective Pressure (COV_IMEP) of an SI internal combustion piston engine. A modern electronically controlled induction ignition system is used during the test. Two fuels are used in the experiment. The reference fuel is gasoline and the tested fuel is ammonia. For the traditional fuel, using an additional ignition coil does not improve COV_IMEP. This parameter for gasoline has an almost constant value for different ignition system charging times. The situation is different for ammonia. This fuel requires high ignition energy. The use of one ignition coil demands a long charging time. For short charging times, unrepeatability of the engine cycles is unacceptable. The use of an additional ignition coil allowed to the charging coil timing to be shortened and the unrepeatable engine cycles to be reduced. This paper determined the maximum charging time of the used ignition coil, above which the spark parameters are worse. In addition, the influence of charging time and number of ignition coils on total spark energy, spark discharge duration, maximum spark power, and voltage during spark discharge for ammonia is presented. The data presented in this paper are developed based on measurements of current and voltage in the secondary winding of the ignition coil. A self-developed electronic device enabling the change in spark energy is used to control the ignition system. This paper also presents the construction of modern ignition systems, describes the functions of selected components, and briefly discusses their diagnostics. Full article

Ammonia is increasingly recognised as a promising carbon-free fuel and hydrogen carrier due to its high hydrogen content, ease of liquefaction, and existing global infrastructure. However, its direct utilisation in combustion systems poses significant challenges, including low flame speed, high ignition temperature, and the formation of nitrogen oxides (NO_X). This review explores catalytic ammonia cracking as a viable method to enhance combustion through in situ hydrogen production. It evaluates traditional catalytic burner designs originally developed for hydrocarbon fuels and assesses their adaptability for ammonia-based applications. Special attention is given to ruthenium- and nickel-based catalysts supported on various oxides and nanostructured materials, evaluating their ammonia conversion efficiency, resistance to sintering, and thermal stability. The impact of the main operational parameters, including reaction temperature and gas hourly space velocity (GHSV), is also discussed. Strategies for combining partial ammonia cracking with stable combustion are studied, with practical issues such as catalyst degradation, NO_X regulation, and system scalability. The analysis highlights recent advancements in structural catalyst support, which have potential for industrial-scale application. This review aims to provide future development of low-emission, high-efficiency catalytic burner systems and advance ammonia’s role in next-generation hydrogen energy technologies. Full article

The combustion of biomass fuels releases alkali metals, which induce severe catalyst deactivation due to alkali metal (K) poisoning in low-temperature ammonia selective catalytic reduction (NH₃-SCR) systems. To address this issue, this study developed a series of heteropoly acid (HPA)-modified Ce/AC catalysts prepared via incipient wetness impregnation. The low-temperature NH₃-SCR performance (80–200 °C) of these catalysts was systematically evaluated, with particular emphasis on their denitrification activity and K-poisoning resistance. The silicotungstic-acid (TSiA)-modified Ce/Ac (TSiA-Ce/AC) catalyst showed an improvement (>20%) in NO conversion activity under the K poisoning condition. The superior K-poisoning resistance of the TSiA-Ce/AC catalyst was attributed to the high density of Brønsted acidic sites and the strong K binding affinity of TSiA, which together protected active sites and preserved the standard SCR reaction pathway under K contaminations. This study proposes a novel strategy for enhancing catalyst K resistance in low-temperature NH₃-SCR systems. Full article

Challenges associated with the homogeneous charge combustion ignition (HCCI) concept include combustion phasing control and a narrow operating window. To address the HCCI engine developmental needs, chemical kinetic solvers have been recently included in the commercial engine simulation toolchains like GT-Suite v2024 upward. This study investigates the feasibility of ammonia (NH₃) and hydrogen (H₂) as dual fuels in homogenous charge compression ignition (HCCI) engines, leveraging chemical kinetics modeling via GT-Suite software v2024. A validated baseline model was adapted with NH₃/H₂ injectors and simulated across varying blending ratios (BR), compression ratios (CR), air–fuel equivalence ratios (ER), and engine speeds. Results reveal that adding 10% H₂ to NH₃ significantly improves ignition. Optimal performance was observed at a CR of 20 and a lean mixture, achieving higher indicated thermal efficiency (about 40%), while keeping the intrinsic advantages of zero-carbon fuel. However, NOx emissions increased with higher ER due to elevated combustion temperatures. The study emphasizes the trade-offs between efficiency and NOx emissions under tested conditions. Finally, despite the single-zone model limitations in neglecting thermal stratification, this study shows that kinetic modeling has great potential for effectively predicting trends in HCCI, thereby demonstrating the promise of NH₃/H₂ blends in HCCI engines for cleaner and efficient combustion, paving the way for advanced dual-fuel combustion concepts. Full article

This paper explores cleaner and techno-economically viable solutions to provide electricity, heat, and cooling using green hydrogen (H₂) and green ammonia (NH₃) across the entire decarbonized value chain. We propose integrating a 100% hydrogen-fueled internal combustion engine (e.g., Jenbacher JMS 420) as a stationary backup solution and comparing its performance with other backup technologies. While electrochemical storage systems, or battery energy storage systems (BESSs), offer fast and reliable short-term energy buffering, they lack flexibility in relocation and typically involve higher costs for extended backup durations. Through five case studies, we highlight that renewable-based energy supply requires additional capacity to bridge longer periods of undersupply. Our results indicate that, for cost reasons, battery–electric solutions alone are not economically feasible for long-term backup. Instead, a more effective system combines both battery and hydrogen storage, where batteries address daily fluctuations and hydrogen engines handle seasonal surpluses. Despite lower overall efficiency, gas engines offer favorable investment and operating costs in backup applications with low annual operating hours. Furthermore, the inherent fuel flexibility of combustion engines eventually will allow green ammonia-based backup systems, particularly as advancements in small-scale thermal cracking become commercially available. Future studies will address CO₂ credit recognition, carbon taxes, and regulatory constraints in developing more effective dispatch and master-planning solutions. Full article

The ammonia energy ratio (AER) is a critical parameter influencing the performance of ammonia/diesel dual-fuel engines. In this study, a numerical simulation was conducted based on a high-pressure dual-fuel (HPDF) direct injection ammonia/diesel engine to investigate the impact of the AER on combustion and emissions under two distinct combustion modes. By adjusting the ammonia start of injection timing (ASOI), the combustion mode was transitioned from diffusion combustion (HPDF1) to partially premixed combustion (HPDF2). The results show that under the HPDF1 mode, a three-stage heat release pattern is observed, and the evolution curves of NO and NO₂ exhibit fluctuations similar to the heat release process. As the AER increases, the second heat release stage is suppressed, the high-temperature region narrows, the ignition delay is extended, and the CA10–CA50 interval shortens, leading to a higher maximum pressure rise rate (MPRR) at a high AER. Conversely, in the HPDF2 mode, the combustion process is characterized by a two-stage heat release. With an increasing AER, the high-temperature region expands, the ignition delay and CA10–CA50 interval are prolonged, while the CA50–CA90 interval shortens, and the MPRR becomes the lowest at a high AER. For both combustion modes, total greenhouse gas (GHG) emissions decrease with an increasing AER. However, in the HPDF2 mode with an AER = 95%, N₂O accounts for up to 78% of the total GHG emissions. Additionally, a trade-off relationship exists between NOx emissions and indicated thermal efficiency (ITE). When the ASOI is set to −8°CA ATDC, the engine operates in a transitional combustion mode between HPDF1 and HPDF2. At this point, setting the AER to 95% effectively mitigates the trade-off, achieving an ITE of 53.56% with NOx emissions as low as 578 ppm. Full article

Gas turbines are widely used in power generation due to their reliability, flexibility, and high efficiency. As the energy sector transitions towards low-carbon alternatives, hydrogen and ammonia are emerging as promising fuels. This study investigates the thermodynamic and combustion performance of a GE LM6000 gas turbine fueled by methane/hydrogen and methane/ammonia fuel blends under varying levels of oxygen enrichment (21%, 30%, and 40% $O_2$ by volume). Steady-state thermodynamic simulations were conducted using Aspen HYSYS, and combustion modeling was performed using ANSYS Chemkin-Pro, assuming a constant thermal input of 102 MW. Results show that increasing hydrogen content significantly raises flame temperature and burning velocity, whereas ammonia reduces both due to its lower reactivity. Net power output and thermal efficiency improved with higher fuel substitution, peaking at 43.46 MW and 42.7% for 100% $N{H}_3$. However, $N{O}_{\mathrm{x}}$ emissions increased with higher hydrogen content and oxygen enrichment, while $N{H}_3$ blends exhibit more complex emission trends. The findings highlight the trade-offs between efficiency and emissions in future low-carbon gas turbine systems. Full article

Piston engines used for powering automobiles as well as machinery and equipment have traditionally relied on petroleum-derived fuels. Subsequently, renewable fuels began to be used in an effort to reduce the combustion of hydrocarbon-based fuels and the associated greenhouse effect. Researchers are currently developing technologies aimed at eliminating fuels containing carbon in their molecular structure, which would effectively minimize the emission of carbon oxides into the atmosphere. Ammonia is considered a highly promising carbon-free fuel with broad applicability in energy systems. It serves as an excellent hydrogen carrier (NH₃), free from many of the storage and transportation limitations associated with pure hydrogen. Safety concerns regarding the storage and transport of hydrogen make ammonia an increasingly important fuel also due to its larger hydrogen storage capacity. This manuscript investigates the use of ammonia for powering a dual-fuel engine. The results indicate that the addition of ammonia improves engine performance; however, it may also lead to an increase in NO_x emissions. Due to the limitations of ammonia as a fuel, approximately 40% of the energy input must still be provided by diesel fuel to achieve optimal engine performance and acceptable NO_x emission levels. The presented research findings highlight the significant potential of NH₃ as an alternative fuel for compression-ignition engines. Proper control of the injection strategy or the adoption of alternative combustion systems may offer a promising approach to reducing greenhouse gas emissions while maintaining satisfactory engine performance parameters. Full article

The urgent need to mitigate climate change and reduce greenhouse gas emissions has accelerated the search for sustainable and scalable energy carriers. Among the different alternatives, ammonia stands out as a promising carbon-free fuel, thanks to its high energy density, efficient storage, and compatibility with existing infrastructure. Moreover, it can be produced through sustainable, green processes. However, its application in internal combustion engines is limited by several challenges, including low reactivity, narrow flammability limits, and high ignition energy. These factors can compromise combustion efficiency and contribute to increased unburned ammonia emissions. To address these limitations, hydrogen has emerged as a complementary fuel in dual-fuel configurations with ammonia. Hydrogen’s high reactivity enhances flame stability, ignition characteristics, and combustion efficiency while reducing emissions of unburned ammonia. This review examines the current status of dual-fuel ammonia and hydrogen combustion strategies in internal combustion engines and summarizes the experimental results. It highlights the potential of dual-fuel systems to optimize engine performance and minimize emissions. It identifies key challenges, knowledge gaps, and future research directions to support the development and widespread adoption of ammonia–hydrogen dual-fuel technologies. Full article

Ammonia combustion has garnered increasing attention due to its potential as a carbon-free fuel. Globally swirling flow in a rectangular furnace generates flameless conditions by high flue gas recirculation. The reverse air injection (RAI) technique enabled stable swirling flameless combustion of pure ammonia without auxiliary methods. Experiments with pure ammonia combustion in a swirling flameless furnace demonstrated an operable equivalence ratio (ER) range of 0.3–1.05, extending conventional flammability limits of pure ammonia as a fuel. NO emissions were reduced by 40% compared to conventional combustion, with peak concentrations of 1245 ppm at ER = 0.71 and near-zero emissions at ER = 1.05. Notably, flameless combustion exhibited lower temperature sensitivity in NO formation; however, the ER has a serious effect. Developing a simplified reaction model for ammonia combustion is crucial for computational fluid dynamics (CFD) research. A reduced kinetic mechanism comprising 36 reactions and 16 chemical species was introduced, specifically designed for efficient and precise modeling of pure ammonia flameless combustion. Combustion simulation using the eddy dissipation concept (EDC) approach confirmed the mechanism’s predictive capability, maintaining acceptable accuracy across the operating conditions. Full article