Combustion Performance Research Articles

Numerical Simulation Study on the Stable Combustion of a 660 MW Supercritical Unit Boiler at Ultra-Low Load

To investigate the safe, stable, and economically viable operation of a boiler under ultra-low-load conditions during the deep peaking process of coal-fired units, a numerical simulation study was conducted on a 660 MW front- and rear-wall hedge cyclone burner boiler. The current research on low load conditions is limited to achieving stable combustion by adjusting the operating parameters, and few effective boiler operating parameter predictions are given for very low-load conditions, i.e., below 20%. Various burner operation modes under ultra-low load conditions were analyzed using computational fluid dynamics (CFDs) methods; this operation was successfully tested with six types of pulverized coal combustion in this paper, and fitting models for outlet flue gas temperature and NOx emissions were derived based on the combustion characteristics of different types of pulverized coal. The results indicate that under 20% ultra-low-load conditions, the use of lower burners leads to a uniform temperature distribution within the furnace, achieving a minimum NOx emission of 112 ppm and a flue gas temperature of 743 K. Coal type 3, with the highest carbon content and a calorific value of 22,440 kJ/kg, has the highest average section temperature of 1435.76 K. In contrast, coal type 1 has a higher nitrogen content, with a maximum cross-sectional average NOx concentration of 865.90 ppm and an exit NOx emission concentration of 800 ppm. The overall lower NOx emissions of coal type 3 are primarily attributed to its reduced nitrogen content and increased oxygen content, which enhance pulverized coal combustion and suppress NOx formation. The fitting models accurately capture the influence of pulverized coal composition on outlet flue gas temperature and NOx emissions. This control strategy can be extended to the stable combustion of many kinds of coal. For validation, the fitting error bar for the predicted outlet flue gas temperature based on the elemental composition of coal type 6 was 8.09%, whereas the fitting error bar for the outlet NOx emissions was only 1.45%.

Flame Speed Measurements of Ammonia–Hydrogen Mixtures for Gas-Turbines

Abstract Recent findings from the U.S. Energy Information Administration project an increase in domestic fossil fuel consumption (e.g., petroleum and natural gas) and global greenhouse gas emissions through 2050 (Nalley, S., 2021, “International Energy Outlook 2021 (IEO2021),” IEO2021 Release, CSIS, Center for Strategic and International Studies, Washington, DC, Technical Presentation, pp. 2–12). Consequently, advanced combustion research aims to identify fuels to mitigate fossil fuel consumption while minimizing exhaust emissions. Ammonia (NH3) is one of these candidates, as it has historically been shown to provide high energy potential and zero-carbon emission (CO and CO2) (Hayakawa, A., Goto, T., Mimoto, R., Arakawa, Y., Kudo, T., and Kobayashi, H., 2015, “Laminar Burning Velocity and Markstein Length of Ammonia/Air Premixed Flames at Various Pressures,” Fuel, 159, pp. 98–106). As a hydrogen (H2) carrier, NH3 serves as a possible solution to the U.S. Department of Energy's Hydrogen Program Plan by providing efficient H2 storage and conservation capabilities (U.S. Department of Energy, 2020, “Department of Energy Hydrogen Program Plan,” U.S. Department of Energy, Washington, DC, Report No. DOE/EE-2128). As a result, applied turbine-combustion research of NH3 and H2 fuel has been conducted to identify combustion performance parameters that aid in the design of sustainable turbomachinery (Chiong, M.-C., Chong, C., Ng, J., Mashruk, S., Chong, W., Samiran, N., Mong, G., and Medina, A., 2021, “Advancements of Combustion Technologies in the Ammonia-Fuelled Engines,” Energy Convers. Manage., 244, p. 114460). One of these key combustion parameters is the laminar burning speed (LBS). While abundant literature exists on the combustion of NH3 and H2 fuels, there is not sufficient evidence in high-pressure environments to provide a comprehensive understanding of NH3 and H2 combustion phenomena in turbine-combustor settings. To advance the state of the knowledge, NH3 and H2 mixtures were ignited in a spherical chamber across a range of equivalence ratios at 296 K and 5 atm to understand their flame characteristics and LBS which was determined using a multizone constant volume method. The experimental conditions were selected according to primary turbine-combustor conditions, as much research is needed to support NH3–H2 applicability in turbomachinery for power generation. The effect of H2 addition to NH3 fuel was observed by comparing the LBS for various NH3–H2 mixture compositions. Experimental results revealed increased LBS values for H2 enriched NH3, with the maximum LBS occurring at stoichiometry. The experimental data were accurately predicted by the University of Central Florida (UCF) NH3–H2 mechanism developed for this investigation, while NUI 1.1 simulations overestimated recorded LBS data by a significant margin. This study demonstrates and quantifies the enhancing effect of H2 addition to NH3 fuels via LBS and strengthens the literature surrounding NH3–H2 combustion reactions for future work.

Simplified mathematical model of oxy-fuel combustion of municipal solid waste in the grate furnace: effect of different flue gas recirculation rates and comparison with conventional mode

Bioenergy carbon capture technology (BioCCS or BECCS) plays a key role in the European Green Deal, which aims to decarbonize industry and energy sectors, resulting in the production of energy with negative CO2 emissions. Due to the biogenic origin of carbon contained in municipal solid waste (MSW), the application of carbon capture in waste incinera-tion plants can be classified as BioCCS. Thus, this technology has attracted scientists' attention recently since it reduces excessive waste and emissions of carbon dioxide. Currently, there are four incineration plants in the Netherlands, Norway and Japan, in which CO2 capture is implemented; however, they are based on the post-combustion technique since it is the most mature method and not requires many changes in the system. Nevertheless, the separation of CO2 from the flue gas flow, which contains mostly nitrogen, is complex and causes a large drop in the total performance of the system. Oxy-fuel combustion technology involves the replacement of air as an oxidizer into high purity oxygen and recirculated exhaust gas. As a result, CO2-rich gas is produced that is practically ready for capture. The main goal of the study is to develop a math-ematical model of oxy-waste combustion to answer the research questions, such as how the composition of oxidant that is supplied to the process affects the combustion performance. The model includes all important processes taking place within the chamber, such as pyrolysis, char burnout and gas combustion over the grate. The results of the work will contribute to the development of oxy-waste incineration plants and will be useful for design purposes.

Assessment of the use of biochar from the slow pyrolysis of walnut and almond shells as an energy carrier

ABSTRACT This study explores the energy applications and combustion kinetics of biochar produced from walnut and almond shells through pyrolysis. Using macro-thermogravimetric analysis at heating rates of 10, 15, and 20 K min−1, a multi-step mechanism involving two parallel reactions was used to model thermal decomposition. Bioenergy indices revealed that walnut shell-based biochar (WSB) produced at 773 K and 873 K displayed superior biofuel potential due to its high energy density and low ash content, while almond shell-based biochar (ASB) at 673 K demonstrated the best overall bioenergy performance. Among the tested heating rates, 15 K min−1 provided optimal results for ignition, combustion, and burnout indices, with WSB showing the highest overall combustion performance. Kinetic analysis using the Coats-Redfern method demonstrated the highest R2 values and minimized RMSE and SSE. The activation energy for the first pseudo-component ranged from 54.91 to 129.84 kJ mol−1 for ASB and from 61.71 to 141.85 kJ mol−1 for WSB. For the second pseudo-component, the activation energy ranged from 25.21 to 159.32 kJ mol−1 for ASB and 25.63 to 96.25 kJ mol−1 for WSB. These findings emphasize the potential of WSB and ASB biochar for bioenergy applications, with WSB exhibiting the best combustion characteristics.

Research on the implementation of free piston engine generator at various compression ratios and combustion performance of multiple fuels

The Free Piston Engine Generator (FPEG) is a novel energy conversion system that directly couples a free piston engine with a linear generator. Its ability to adjust the compression ratio over a wide range without complex auxiliary structures and its adaptability to different fuels have garnered significant attention. To improve the efficiency and cleanliness of FPEG, This study employs an FPEG prototype test bench, using ethanol and n-propanol as raw materials, mixed with aviation kerosene (RP-3) at volume ratios of 20 %, 40 %, and 60 %, respectively. It investigates the impact mechanisms and operating characteristics of different running parameters on the compression ratio of FPEG when using different fuels, and to analyze the combustion and emission characteristics of FPEG under various compression ratio conditions. The results show that compared to gasoline, the alcohol/RP-3 mixtures (with alcohol content >40 %) have higher brake thermal efficiency and significantly reduced CO emissions. As the compression ratio increases, the brake thermal efficiency of alcohol/RP-3 mixtures further improves, while CO and HC emissions decrease. At higher compression ratios, the n-propanol/kerosene blends show higher efficiency and lower CO and HC emissions. These findings provide important insights into the multi-fuel application of FPEG and the potential for cleaner energy conversion.

Numerical Investigation of CO and NO Production From Premixed Hydrogen/Methane Fuel Blends

Abstract There is significant interest in utilizing hydrogen as an energy carrier in a net-zero carbon energy economy. A variety of fundamental and practical issues associated with premixed hydrogen/methane combustion must be addressed, particularly flame flashback, combustion instabilities, and NOx emissions. Significantly less attention has been given to CO emissions from hydrogen blending. However, recent H2 blending engine tests have clearly noted major reductions in CO emissions, reductions which substantially exceed what would be expected based upon C atom mass balances in the fuel. Moreover, NOx, CO, and combustor operability always tradeoff with each other, and so, for example, these CO reductions can also enable operational or design modifications to reduce NOx emissions and/or wider operability windows. This paper addresses H2 blending effects on CO emissions, addressing both the direct influences on CO emissions, as well as how it influences NOx–CO tradeoffs. The paper presents computations that differentiate between the kinetic and equilibrium effects of H2 blending, as well as how H2 blending can lead to reductions in both NOx and CO by moving the Pareto front downward. Finally, this work suggests that H2 blending, in addition to its CO2 reductions, can also increase plant operational flexibility and so provide additional value propositions to an evolving electricity market.

The Effect of Bioalcohol Additives on Biofuel Diesel Engines

This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the focus was placed on investigating the specific impacts of ethanol and n-butanol additives on diesel engine performance. Research shows that a fuel mixture consisting of 70% diesel, 10% biodiesel, and 20% ethanol reduced NOx emissions by 5.56% compared to pure diesel at 75% load. Furthermore, this study explores the combustion performance of diesel/biodiesel blended with butanol/ethanol. The findings indicate that n-butanol improves thermal efficiency, particularly at 100% load, with the D70B10E20 and D70B10BU20 blends demonstrating thermal efficiencies of 9.94%and 8.72% higher than that of diesel alone, respectively. All mixed fuels exhibited reduced hydrocarbon and CO emissions under different loads, with a notable reduction in hydrocarbon emissions of 34.4% to 46.1% at 75% load.

Combustion performance of an evaporative flameholder under subsonic-supersonic mixing inflow

The combustion process in rocket-assisted subsonic ramjet engines represents a key advancement in integrated aerospace propulsion, particularly for embedded rocket-based systems. These engines offer the potential to improve combustion performance at altitudes of 25–35 km. However, the significant temperature and velocity differentials between the rocket jet and the subsonic ramjet flow restrict heat and mass transfer. Investigating the relationship between combustion performance and inlet parameters under subsonic-supersonic mixing conditions offers a promising approach to enhancing thrust performance. This study introduces subsonic and supersonic airflow mixing via a flat-plate shear layer in a rectangular channel, with an evaporative flameholder placed centrally to assess combustion. Results reveal that combustion efficiency decreases as the equivalence ratio exceeds 0.2, while the static temperature ratio has minimal impact on efficiency but strongly influences the maximum flame stabilization limit. As the temperature ratio increases from 1.30 to 1.80, the flame limit narrows from 1.656 to 0.237. Higher pressure ratios initially enhance combustion efficiency and flame coverage but eventually cause a decrease. The flame limit broadens from 0.900 to 1.626 as the pressure ratio increases from 1.12 to 1.50. While Mach number changes have little effect on efficiency, the flame limit exhibits an initial rise followed by a drop. Novel findings include an asymmetrical flame pattern and a “Z” shaped outlet temperature distribution, contributing to optimized combustion strategies for combined-cycle engines.

In situ iron coating of amorphous boron and characterization of its energy release behavior

Boron was widely employed as metal fuel in solid propellants for its higher gravimetric and volumetric combustion enthalpies. However, the low melting point and high boiling point of B2O3 on the surface of boron particles significantly hinder its ignition and combustion performance, seriously preventing the full realization of its thermodynamic potential. To address this issue, B@Fe composite fuels with different iron contents from 1.59 % to 7.09 % were prepared via liquid phase reduction in this paper and the quasi-static high temperature oxidation, ignition and combustion reaction characteristics and corresponding mechanism were studied, in order to provide effective modification techniques in supporting the large-scale engineering application of boron as metal fuel. The study results show that B@Fe can effectively reduce the ignition temperature and maximum heat flow temperature of amorphous boron, and increase the maximum mass gain rate. The ignition temperature and maximum heat flow temperature have an exponential function with the iron coating content. Iron coated amorphous boron can effectively shorten the laser ignition delay time by more than 50 %, and significantly change the flame structure, flame evolution process and combustion duration. Both amorphous boron and iron-coated amorphous boron flame showed a multi-layer structure, including the outer green flame, the middle yellow flame and the central incandescent flame. However, with the increase of the iron coating content, the flame height increased from 5.5 cm to 6.3 cm, the flame structure changed from mushroom type to triangle type, and the central incandescent flame area increased significantly. The equivalent combustion duration increased from 975 ms to 1997 ms, and the flame temperature increased from 1288 to 1505 °C. The emission spectra of BO2 and BO lines are captured during combustion. B@Fe with the increase of iron content, a large number of small diameter micropores appear in the condensed combustion products(CCPs) of composite fuels, and a grid-like structure was formed. With the increase of iron coating content, the boron content of condensed combustion products decreases, and the oxygen content increases. The main components of CCP include B, B2O3, B6O, FeB, Fe2B and Fe3B. Based on the ignition combustion experiment of B@Fe composite fuel, ignition combustion analysis model of B@Fe composite fuel was established.

Bioenergy and bioexergy analyses with artificial intelligence application on combustion of recycled hardwood and softwood wastes

Novel biomass bioenergy-bioexergy analyses via thermogravimetry analysis and artificial intelligence are employed to evaluate the three biofuels from wood wastes (softwood-SW, hardwood-HW, and woods blend-WB). The chemical characterization of SW has the highest bioenergy (higher heating value – HHV: 18.84 MJ·kg-1) and bioexergy (specific chemical bioexergy – SCB: 19.65 MJ·kg-1) with the SCB/HHV ratio of wood waste as about 1.043-1.046. The high C-element has a significant influence on the HHV-SCB. The SCB/HHV ratio of wood waste is recognized as about 1.043-1.046. The three distinct zones of wood waste combustion are identified: moisture evaporation (Zone I, up to 110 °C), combustion reaction – degradation of three major lignocellulosic components (hemicelluloses, cellulose, and lignin) at Zone II, 110-600 °C, and ash remains (Zone III, 600-800 °C). The ignition (Dig=0.01-0.04) and fuel reactivity (Rfuel=3.82-6.97 %·min-1·°C-1) indexes are evaluated. The comprehensive combustion index (Sn:>5×10-7%2·min-2·°C-3) suggests that wood waste has a better combustion performance than bituminous coal. The statistical evaluation presents that the highest HHV-SCB values are obtained by performing combustion for SW-250 μm at 15 °C·min-1. The S/N ratio and ANOVA results agree that the wood waste type and particle size denote the most influential parameters. The artificial neural network prediction shows an excellent result (R2=1) with 1 hidden layer and 5 neuron configurations.

Enhancing energy release and controlled combustion of B-based MICs by the synergistic effect between polyvinyl pyrrolidone and nitrocellulose

To enhance energy release of boron-based metastable intermixed composites (MICs), a series of B-based MICs were constructed successfully by a facile one-step sol-freeze-drying (SFD) method, where copper oxide (CuO) was employed as oxidant. The structure, morphology, chemical state and specific surface area of B-based MICs were investigated by several characterization technologies, and their reactivity and combustion performance were further studied by various experimental tests. The results reveal that B and CuO nanoparticles were dispersed evenly on a nest network braided by the molecular interaction between polyvinyl pyrrolidone (PVP) and nitrocellulose (NC), and the constant volume combustion heat of B-based MICs even reaches 8956.6 ± 76.6 J·g−1 when PVP (1.25 wt%) and NC (5.0 wt%) were added into B/CuO. The heat value is about 1.7 times as big as pristine B/CuO (5345.5 ± 36.1 J·g−1) and approaches to that of raw B NPs (10335.5 ± 507.8 J·g−1). Moreover, the condensed phase residues of three composites were confirmed to be Cu and Cu2O, while the smallest particle size distribution of product proves that the combustion of B/CuO/NC(NC: 5.0 wt%, PVP: 1.25 wt%) is most complete. So the unique nest network can eliminate particle aggregation, shorten the transfer distance of mass and heat and improve the “solid − solid” thermite reaction. This work will provide a new strategy for promoting the application of boron

Effect of swirler geometry on the outlet temperature profile performance of a model gas turbine combustor

Effect of swirler geometry on the outlet temperature profile performance of a model gas turbine combustor

Combustion Characteristics and Performance of Nanoflower Structure AlB2@AP Energetic Composites

ABSTRACT Boron-based solids have garnered significant attention due to their high calorific value. However, during combustion, the formation of boron oxide (B₂O₃) on the surface hinders the interaction between the oxidizing components and the internal active boron (B), thereby limiting its reactivity and combustion efficiency. Modifying boron-based solids represents an effective strategy for overcoming the limitations associated with fuel energy release efficiency. In this study, a shell-structured AlB₂@AP composite was designed and fabricated utilizing etching and recrystallization methods. The structure comprises AlB₂ as the core, B as the middle shell, and AP as the embedded outer shell. The key strategy involves employing an etching process to augment the reactive surface area of boron on the aluminum diboride surface, while also coating it with ammonium perchlorate (AP) to enhance the composite particles. This innovative approach demonstrates that the etching method can effectively utilize the boron present in AlB₂. The composite particles were characterized and analyzed for morphology employing a scanning electron microscope and X-ray techniques. Thermal analysis indicated that the decomposition stage of AP facilitated the oxidation of etched AlB₂, moreover, as the AP coating content increased, the temperature at which vigorous reactions initiated occurred earlier. In combustion experiments, the maximum combustion temperatures of AlB₂@10AP, AlB₂@20AP, and AlB₂@30AP increased by 36.4%, 15.1%, and 3.8%, respectively. The combustion formulation prepared with elemental boron exhibited different characteristics. The average combustion temperatures increased by 33.1%, 23.4%, and 14.4%, respectively. The combustion durations were reduced by 60.8%, 33.7%, and 31.7%, respectively. AlB2@AP is anticipated to further enhance its applications in propellants, explosives, and pyrotechnics.

Operation parameters investigation on combustion and emission of a non-road diesel engine based on orthogonal experiment design at different altitudes

For improving the combustion and emission performance of engines operating at high altitude regions, a two OED optimization method was proposed. The influence of each factor on the target was analyzed and discussed through a primary OED. Based on the primary OED test, factors with less influence were excluded to reduce factors in the secondary OED test. The results showed that low intake pressure led to poor spray mixing, prolonged ignition delay, and incomplete combustion, resulting in deteriorated power output, fuel economy, and emission characteristics. After two OED optimizations, The NOx emissions increased significantly by 40.5 % and 122.5 % in the first and second optimization, respectively, however, the ISFC decreased by 13.4 % and 25.2 %, and CO decreased by 13.0 % and 25.2 % in the first and second optimization, respectively, as well as ultra-low carbon smoke emissions was achieved. The related theories and methods' advantage can be extended to engineering applications and has good practical value.

Laminar burning characteristics of ammonia and hydrogen blends at elevated initial pressures up to 2.5 MPa

Ammonia is a highly promising alternative fuel, and blending it with hydrogen can mitigate its poor combustion performance. However, the combustion mechanism of ammonia-hydrogen mixtures requires further validation through measurements of laminar burning velocity, particularly under high-pressure conditions relevant to practical combustors. Experimental data at high initial pressures (>1.0 MPa) are notably scarce. In this study, experiments were conducted using an outwardly propagating spherical flame in a high-pressure, high-temperature, constant-volume combustion chamber to determine the laminar burning velocities of ammonia-hydrogen blends at elevated initial pressures. The effects of different equivalence ratios (0.6 ∼ 1.4), volumetric hydrogen ratios (0.1 ∼ 0.6), and initial pressures (0.1 ∼ 2.5 MPa) were evaluated. Chemical kinetics of ammonia and hydrogen combustion was investigated at high pressures. The experimental results were compared with the simulation results under a wide range of conditions using several existing mechanisms to evaluate their applicability. The results show that the laminar burning velocity increases first and then decreases as the equivalence ratio (ϕ) increases and reaches a maximum value around ϕ of 1.1. The laminar burning velocity increases non-linearly with the volumetric hydrogen ratio, with more pronounced acceleration at higher hydrogen ratios. In contrast, the laminar burning velocity decreases non-linearly with the increasing initial pressure, and this reduction becomes progressively slower as the initial pressure rises. The predictive performance of the mechanisms by Okafor et al. and Gotama et al. is relatively satisfactory under certain conditions, but further optimization based on experimental data is necessary. Additionally, reaction pathway analysis of ammonia-hydrogen combustion indicates that introducing hydrogen increases the concentration of active radicals such as OH, O, and H, thereby enhancing ammonia combustion. Sensitivity analysis of the laminar burning velocity identified the critical elementary reactions across varying pressures, providing strong support for optimizing ammonia-hydrogen chemical kinetics models and developing simulation models for practical combustion systems.

Experimental study on the thermal insulation performance of semi-transparent materials based on convection heating method

Radiation heat transfer inside the aerogel materials belongs to medium radiation, so different heating methods have different measurement results of thermal conductivity. For aerogel materials applied in high temperature air flow environment (aerospace field), since the real boundary conditions of aerogel materials during operation can be simulated by convection heating method (CHM), the combustion-gas wind tunnel device based on two-stages atomization, two-stages combustion/mixing mode is constructed, and the performance test is conducted. The operation safety and combustion performance of the device meet the test requirements, so the thermal conductivity test of aerogel materials can be carried out. When the average temperatures are 469 K, 622 K and 763 K respectively, the effective thermal conductivity (ETC) measured by the CHM is smaller than that measured by the thermal conduction heating method (TCHM), which decreases by 2.7 %, 7.84 % and 9.23 % respectively. The CHM solves the limitations of the TCHM, so the ETC of aerogel materials measured by CHM is more valuable for the design of thermal protection system.

Study on combustion characteristics of ammonium perchlorate enhanced hydroxylamine nitrate-based electronically controlled solid propellant

Electrically controlled solid propellants (ECSPs) have attracted significant attention as a novel class of solid propellants owing to their unique electrochemical properties. In this study, a series of ECSP formulations composed of hydroxylammonium nitrate (HAN), ammonium perchlorate (AP), and polyvinyl alcohol (PVA) were prepared and experimentally investigated to understand the effect of applied voltage on their combustion characteristics, and their combustion behavior was systematically characterized. The results demonstrated that the addition of AP decreased the initial conductivity of the ECSP; however, the average combustion rate during steady-state burning increased significantly, along with a corresponding increase in the combustion temperature. This effect became more pronounced with increasing AP concentration. The dissolved AP in the system acts as an efficient charge carrier, whereas the undissolved AP enhances the combustion performance by producing oxygen through thermal decomposition. Furthermore, even under atmospheric pressure conditions, the combustion of the ECSP can be effectively controlled by adjusting the applied voltage, with combustion ceasing upon removal of the voltage. The mechanism by which AP enhances combustion was analyzed, providing new insights for the optimization of ECSP formulations.

Ideal Co-NiO solid solution with excellent low-temperature propene catalytic combustion performance

Doping engineering of transitional metal oxides offers a great opportunity to further optimize the performance of corresponding catalysts. Here, we presented a solid-state co-precipitation routine to synthesize the Co-NiO ideal solid solution, where Co atoms achieved nearly atomically isolation in the NiO lattice matrix. Remarkably a clear correlation was established between the reactivity for propene combustion and the Co dopant amounts, with the propene combustion rate increasing proportionally to the Co dopant amounts. The homogeneously dispersed Co single atoms or tiny CoOx nanoclusters ensure this linear relationship. More importantly, due to the emergence of Co single atoms and CoOx nanoclusters with a lower coordination number, significant propene adsorption and subsequent C = C bond dissociation were observed in this Co-doped NiO, which improved the propene combustion reaction rate. Therefore, this solid-state co-precipitation strategy provides an effective doping route for building an ideal doped solid solution.

Precise fabrication and superior combustion properties of n-B pomegranate microspheres based on a new dissolution-dispersion-coating method

To enhance the reactivity and combustion efficacy of boron powders, a new dissolution-dispersion-coating (DDC) method of fabricating nano-boron (n-B) pomegranate microspheres were developed. Metal nanoparticles were uniformly encapsulated within n-B microspheres, which varied in size from 2 to 500 μm. The spheroidization mechanism of microsphere structure was investigated. Subsequently, the ignition and combustion performance of the prepared pomegranate microspheres were evaluated by combustion tests at 0.2 and 0.5 MPa, respectively. The results demonstrated that the n-B microspheres of F5 (75 wt% n-B@17 wt% NC@8 wt% n-Ti) exhibited superior performances, achieving the largest flame area, minimal ignition delay time and combustion time. The combustion thermal value and combustion residue analysis indicated that the content of available boron in the F5 microspheres exceeded 72.6 % and the combustion was complete. This study provides a novel approach to enhance the ignition and combustion efficiency of n-B powders.

Direct near-infrared laser ignition of CL-20 by introducing DATNBI as a bi-functional additive: Energetic photosensitizer and self-assembly stimulator

The ignition strategy of energetic materials using low-energy near-infrared (NIR) laser has garnered significant attention due to its enhanced safety and reliability. This study explores the use of a relatively photosensitive but mechanical insensitive energetic material, DATNBI, to facilitate the self-assembly of nano-CL-20 crystals into polycrystalline particles though solvothermal induction, yielding a rough structure conducive to NIR laser ignition. The findings demonstrate that by adjusting the content of DATNBI, it is possible to achieve micro-nano controllable spherical CL-20/DATNBI (C/D) particles, with CL-20 as the primary component and DATNBI as the auxiliary component. The incorporation of DATNBI and the rough surface structure enhance the light absorption of C/D particles in the NIR band. Additionally, the unique synergistic effect between CL-20 and DATNBI during thermal decomposition further promotes NIR laser ignition. As expected, the C/D particles achieved self-sustained combustion and exhibited excellent combustion performance under a 1064 nm laser, which is challenging to be achieved with raw CL-20 or raw DATNBI. Furthermore, the relatively insensitive DATNBI and spherical structure reduced the impact sensitivity of the C/D particles. This multifunctional material strategy, integrating energy, safety environment-friendliness, and laser ignition performance, offers a novel approach for laser ignition of energetic materials.