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The present study successfully synthesized MnWO4@g-C3N4 and CuWO4@g-C3N4 nanocomposites which demonstrated high efficiency and recoverability as a robust catalyst for ODS of model (DBT) and real fuel oil (kerosene and diesel). The manufactured composites were thoroughly characterized using XRD, TGA, FTIR, SEM and EDX confirming its physicochemical properties. The SEM results revealed that MnWO4 and CuWO4 nanoparticles were well organized on the exterior of g-C3N4 forming interesting spherical particle morphology. Under optimized conditions, the nanocomposites MnWO4@g-C3N4 and CuWO4@g-C3N4 exhibited an impressive 98 and 98.5% removal of DBT, respectively from the model fuel (100 mg/L) within 180 min at a temperature of 45 °C using 1 mL of oxidant and 0.1 g of catalyst amount. Furthermore, the catalytic activity of composites was investigated for real fuel desulfurization and promising results were achieved. Moreover, the fuel properties were in accordance with ASTM specifications. The study found that the desulfurization reaction followed the pseudo 1st order kinetic models and the negative ∆G indicated a spontaneous method. The nanocomposites exhibited promising reusability as it could be used up to five times without significantly reducing their ability to desulfurize fuel oil. The study highlights its potential for practical applications in reducing sulfur content in fuel oils contributing to cleaner and environment friendly energy production and utilization. [ABSTRACT FROM AUTHOR]

Turbine engines are currently one of the most important and expensive aircraft components. Both for economic and safety reasons, high engine reliability is required. Therefore, sophisticated methods are needed to determine their current condition. Diagnostics of turbine engines allow for the detection of faults before they lead to damage. The article presents methods and results of vibroacoustic diagnostics of a miniature GTM400 jet engine adapted to kerosene and hydrogen fuel supply. During thermal and vibroacoustic tests of engine parameters powered by hydrogen fuel supply, the engine seized up in the initial start-up phase due to improper control and rapid thermal changes in the gas line. The cause of the undesirable technical condition of the engine was a significantly higher temperature of gases (exhaust gases) affecting the working elements of the engine (turbine shaft, rotor, and blades), which consequently led to engine damage. This phenomenon and the results obtained from the unexpected technical condition constitute a valuable premise for considering the issue of proper operation of the turbojet engine during fuel changes, especially following current trends related to the decarbonization of the aviation sector. The obtained research results and the resulting observations and conclusions make it necessary to perform technical analyses and pre-implementation tests each time before allowing the use of a conventional engine if it undergoes the process of reconstruction in terms of using a new fuel (especially if its technical parameters are different from the originally used one). The presented method of conducting tests allows for a detailed determination of the causes of damage to the cooperating elements of the engine structure under the influence of changes in operating parameters. [ABSTRACT FROM AUTHOR]

This paper describes the pulse injection of kerosene fuel in a kerosene-fueled supersonic combustor at a Mach number of 3. A high-flow mechanical pulsed injector was utilized to inject kerosene at frequencies ranging from 40 to 212 Hz in experiments. High-speed Schlieren images and wall pressure were employed to analyze the influences of various injection frequencies on the wave family and kerosene combustion performance. Initially, the pulsed injection causes intermittent changes in the wave family after kerosene ignition, leading to combustion instability. However, an optimal injection frequency of 143 Hz stabilizes the wave family. Additionally, pulsed injection reduces the kerosene ignition delay time, with the most notable reduction occurring at 113 Hz. Finally, the average combustion intensity of kerosene with pulse injection is lower than that of steady injection. However, the instantaneous combustion intensity at 143 Hz is similar to steady injection, which constitutes a significant portion of the overall combustion process. In summary, pulse injection of kerosene at 143 Hz could achieve efficient and stable combustion at a Mach number of 3. • Pulse injection of kerosene results in intermittent changes in the flow field. • An optimal injection frequency contributes to a continuous flow field. • Pulse injection can shorten the ignition delay time of kerosene. • An optimal injection frequency can enhance kerosene combustion efficiency. [ABSTRACT FROM AUTHOR]

Background: Cooking using open fires or inefficient stoves fuelled by kerosene, biomass (wood, animal dung and crop waste) and coal generates harmful household air pollution. This study tried to estimate the proportion of Households with primary reliance on clean fuels and technology for cooking in India and determine the factors associated with it using the National Family Health Survey (NFHS) 5 data. Materials and methods: We used data from the 2019–2021, National Family Health Survey (NFHS-5) household level data. Clean cooking fuel was considered as household’s who are using electricity, LPG, biogas, natural gas and unclean cooking fuel was considered as any other fuel other than clean fuel. Multivariate logistic regression was performed to estimate the determinants of usage of unclean cooking fuel. Results: Total 6,36,699 households were included in final analysis. The national level proportion of household’s using clean fuel for cooking was 53%. Muslims, Sothern states, households with male Head of the Family (HoF), richest wealth index households, HoF with higher education status were more likely using clean fuels. Whereas Rural households, scheduled tribe households, households with kutcha houses, non-nuclear families and unmarried Hof were more likely using unclean fuels. Conclusions: More than 50 percentage of households do not have access to clean fuels and technologies for cooking. Focus should be on providing access to North Indian states, rural households, households with female as head of the family (HoF), HoF with poor education, non-nuclear families and Scheduled tribe households to fill the gap to achieve Sustainable Development goals (SDG) target by 2030. [ABSTRACT FROM AUTHOR]

In this study, an organic ligand ADCTP (Ammonium O, O dicetyl dithiophosphate) was synthesized and used as an antistatic additive for the first time in the kerosene fuel. The ignition hazard assessment of the ADCTP dispersed kerosene fuel was evaluated from three aspects: Physical phase structure analysis, thermal analysis and process safety parameters analysis. The physical state and thermal analysis were characterized using experimental techniques such as UV visible spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FTIR), Nuclear magnetic resonance (NMR) and Thermogravimetric analysis (TGA). In order to determine the process safety parameters, the antistatic doped fuel was manifested in terms of electrical conductivity, thermal conductivity, viscosity, stability, aging, and relaxation time. The results indicated an enhancement of electrical conductivity of the kerosene fuel up to 790 pS/m for 1000 ppm addition of ADCTP ligand and it will dissipate the generated and accumulated static charges. The ADCTP dispersed fuel was found to be thermally stable up to 200 °C. A laudable reduction in the relaxation time of static charges from 3 sec to 0.04 sec was also observed. This study revealed that, the organic ligand ADCTP is found to be a potential additive to reduce the ignition hazards. [ABSTRACT FROM AUTHOR]

The aerosol emission measurement at sources is crucial for effective environmental regulations and upgradation to global air quality standards. In the present study a Versatile Source Sampling System (VS3) has been designed, fabricated and evaluated to capture emissions from various sources. This study addresses key operational challenges such as isokinetic conditions for aerosol collection, mimicking rapid exhaust and zero-air mixing for gas-to-particle partitioning, and maintaining uninterrupted power supply. Depending upon the emission source, i.e., area, line or point, the aerosol sampling probes and a portable ejector dilutor with dilution tunnel were designed and evaluated in the laboratory and on-field for mixing and particle losses at three dilution ratios 20:1, 30:1, and 40:1. Particle loss experiments were done with sodium chloride and polystyrene latex aerosols. The on-field measurements were carried out with diesel generator, truck and light motor vehicle-goods. The overall particle losses were found to be 8% in the inlet designed for area source measurement, 1-3% for the ejector with dilution tunnel, and 9% and 13% for line and point source sampling inlets, respectively. There was no significant change (p-value > 0.05) in the average particle geometric mean diameter inside the dilution tunnel at different dilution ratios indicating no coagulation. For the first time, this study has reported the PM2.5 (particles with aerodynamic diameter <2.5 µm) emission factor of kerosene fuel used in diesel generator in rural areas for commercial use with values identified between 44 ± 16 gkg−1 accounting 30% Organic Carbon (OC) and 16% Elemental Carbon (EC). [ABSTRACT FROM AUTHOR]

This study introduces a novel approach to analysing the combustion process using a high-speed, non-contact, optical fibre-coupled Si avalanche photodiode (APD)-based infrared radiation thermometer (IRT). The Si APD-IRT, combined with an optimised field-programmable gate array (FPGA)-based digital design, achieves a response time of 1 µs, faster than commercially available instruments. Our instrument captures the entire ignition and reignition cycle of a Jet A kerosene droplet with high temporal precision within a combustion chamber, a feat impossible with traditional thermocouples. The FPGA module was validated with a 1 µs data acquisition time, using a 40 MHz onboard clock, achieving throughput of 0.64 Gbps with efficiencies of 0.062 Mbps/slice in lookup tables (LUTs), confirming a low-area design compared to conventional FPGAs. The IRT achieves a root mean square (RMS) noise specification of 0.5 °C at a 1 µs acquisition time and a target temperature of approximately 1000 °C. A measurement uncertainty of within ±0.25% °C + 2 °C confirms that it lies within the bounds of commercial instrumentations. Our instrument was demonstrated to capture transient temperature fluctuations during combustion and characterises Jet A kerosene fuel droplets, laying the foundation for understanding sustainable aviation fuels (SAFs) and their role in transitioning from aviation fossil fuels, enabling effective research and development. [ABSTRACT FROM AUTHOR]

In order to determine the optimal wall pressure location as the controlled parameter for kerosene-fueled scramjet, a combined approach of numerical simulation and experimental analysis was employed. The results indicate that with an increase in the equivalence ratio of kerosene, the combustor exhibits consecutive modes, including pure scramjet mode, dual-mode scramjet mode, dual-mode ramjet mode, and pressure disturbance to the isolator inlet mode. The peak pressure ratios corresponding to the mode transition boundaries are 1.95, 3.26, and 3.57, with respective isolator outlet Mach numbers of 1.62, 1.0, and 0.74. The equivalence ratio corresponding to mode transition increases with an increase in the combustor inlet total temperature. Considering the dynamic characteristics of wall pressures at different locations, the position at x/L = 0.46 demonstrates the best linearity, highest sensitivity, and greater stability. Hence, it is the most suitable choice as the controlled parameter for fuel flow in this kerosene-fueled scramjet. [ABSTRACT FROM AUTHOR]

The aim of this work is to describe an approach to the formulation of surrogates of hydrocarbon fuels, taking into account the properties related to atomization, heating, evaporation and combustion behaviors. These properties include the density, viscosity, lower calorific value, distillation curve, saturated vapor pressure, heat capacity, thermal conductivity, surface tension, molar ratio of hydrogen to carbon, molar mass, derived cetane number, and threshold soot index. Three diesel surrogates were developed using the proposed approach. Methods for calculating the physicochemical properties of both individual hydrocarbons and their mixtures are presented. The discrepancy between calculated results and experimental data for all properties is shown not to exceed 3%. Experimental studies were carried out in a lab-scaled combustion chamber, in which the properties of one of the three developed surrogates, DSSU3, were compared with those of diesel fuel. Also, the simulation results for DSSU3 were compared with published experimental data. It is shown that the properties of DSSU3 are a good match for those of diesel fuel. In addition, a kerosene surrogate was formed using the proposed approach. This allowed us to conclude that this approach to determining the properties of multi-component fuels is suitable for the formulation of both kerosene and diesel fuel surrogates. [ABSTRACT FROM AUTHOR]

The characteristics of the multi-strut equipped large aspect ratio supersonic combustor fueled with liquid kerosene were observed to deepen understanding of the combustion characteristics. Some numerical simulations and experiments have been carried on at the condition of Tt = 1680K, Pt = 1.68Mpa, and Ma = 2.8. The mixing and combustion performances of liquid kerosene under the different fuel injection methods are studied by numerical calculation. The results show that with the multi-struts injection method, the fuel distribution can be optimized, and combustion performance is improved by 60%. Then, three different strut arrangement schemes are proposed by designing the relative position between the leading edge shock wave of the ignition strut and the injection strut. The shock field structure and total pressure loss in different cases are discussed, and a low-resistance strut arrangement scheme is obtained. The mixing efficiency of the liquid fuel is discussed, and the effect of the shock wave on the fuel vaporization process is analyzed by using the two-phase flow model. The results show that the process of fragmentation and atomization of the gaseous fuel is promoted by the shock wave, which improves the mixing efficiency. The influence of the arrangement scheme of the multi-struts on the combustion efficiency is analyzed. The degree of flame overlap increases rapidly at a small distance between struts, which makes the combustion efficiency drop by 30%. Finally, combined with the research contents of this paper, a design method of the multi-strut arrangement scheme is proposed, and the feasibility of the design method is verified by experiments. The results of this paper are beneficial for the future performance optimization of multi-strut combustors using liquid kerosene as fuel. [ABSTRACT FROM AUTHOR]

Hydrocracked kerosene represents an additional source of jet fuel in oil refineries. The objective of this study was to re-distill hydrocracked kerosene (distillation range of 155-211 °C) into narrow cuts (distillation range of 10 °C) and to determine the dependence of the critical parameters of jet fuel, i.e., density, aromatics, smoke, and freezing point on the mean boiling point (tmean) of these cuts, utilizing modern and well established analytical methods. Re-distillation yielded seven narrow cuts composed of hydrocarbons with maximally three different carbon numbers. The analyzed properties deteriorated significantly with increasing tmean of cuts. Already the cuts with tmean of 190 °C + did not meet the jet fuel specification for aromatics and the 210 °C + cut did not meet any of the studied properties. Aromatics were crucial in controlling the distillation range and this provided an explanation for why hydrocracked jet fuel can be produced only as a narrow fraction. Since a low freezing point characterized all narrow cuts, this property represents a crucial synergy of blending of the hydrocracked kerosene with a straight-run kerosene or SAF. Overall, we demonstrated that narrow-cut research provides new insights into the characteristics of the hydrocracked kerosene. [ABSTRACT FROM AUTHOR]

The ignition and flame propagation process within the centrally staged annular combustor is considerably intricate, particularly under low pressure conditions. Experiments with kerosene as fuel were conducted under varying pressures ranging from 30 to 90 kPa. A high-speed camera was employed to capture images of the ignition process. The experiments illustrate that the fuel–air ratio at the ignition boundary initially decreases and then increases with increasing pressure drop at different inlet pressures. The ratio increases as the pressure decreases at a constant pressure drop, exhibiting a more pronounced effect, particularly at lower pressures. The flame propagation time of annular combustion is shortened by the increase in the fuel–air ratio. Moreover, an increase in pressure drop enhances flame propagation speed and reduces flame propagation time. Under identical working conditions and parameters, lower inlet pressures result in longer flame propagation time. Additionally, asymmetry is observed in circumferential flame propagation within the annular combustor. Since the swirl flow direction exhibits faster propagation speeds, the ratio of propagation speeds remains nearly constant across different directions. Furthermore, distinct flame propagation paths are identified in various directions. Three different flame propagation patterns were observed, including "archlike-axial," "entrainment-rotation," and "sweep-transverse." Fuel–air ratio and pressure drop serve as primary parameters governing flame propagation patterns. The flame propagation pattern exhibits similarities to that of atmospheric conditions, with the exception of the inhibition observed in the entrainment-rotation pattern. Notably, compared to the ignition between two adjacent burners, ignition in the middle of a certain burner shows a higher probability of successful ignition. [ABSTRACT FROM AUTHOR]

In this study, the differences in the combustion process of ammonia-premixed ignition with conventional diesel and kerosene as pilot fuels were investigated based on flame chemiluminescence, and further study on the effects of ammonia ratio (AMR) and direct injection timing (DIT) on the ammonia-kerosene dual-fuel combustion (AKDC) process was carried out. The results show that the kerosene with stronger volatility is more conducive to promoting rapid and stable combustion of ammonia. A composite flame structure is observed in dual-fuel modes. With the increase of AMR, the capacity to ignite ammonia is lessened, the flame area and luminosity are stabilized and then reduced, and the flame hue is transformed from blue-green to yellow. Higher combustion rates are observed when the DIT lies between −9° and −12° CA ATDC, resulting in higher flame area and luminosity. The overly advanced or delayed DIT leads to the deterioration of ammonia combustion. • An optical study of the AKDC and ADDC mode was conducted. • A composite flame structure is observed in AKDC and ADDC modes. • Kerosene is more conducive to the ignition of ammonia than diesel. • As AKDC phases are roughly the same, the combustion state of pilot fuel dominates. • Adjusting the phase of AKDC towards TDC via DIT helps the rapid combustion of it. [ABSTRACT FROM AUTHOR]

In order to study the effect of coal-based kerosene on physical and chemical properties of jet fuel, the coal-based kerosene has been added to jet fuel, and the more than 20 kinds of physical and chemical properties of jet fuel have been tested according to national standard«No.3 jet fuel» (GB 6537). The results show that the physical and chemical properties of jet fuel containing coal-based kerosene meet the requirements of national standard «No. 3 jet fuel» (GB 6537). When the volume content of coal-based kerosene increases, 11 kinds of properties of the jet fuel behave monotonic variation, 13 kinds of properties keep unchanged. It can be seen that jet fuel containing coal-based kerosene still meets the requirements of national standard «No. 3 jet fuel» (GB 6537), whereas the coal-based kerosene has different influence on properties of jet fuel. [ABSTRACT FROM AUTHOR]

This study investigates the performance and environmental impact of n-butanol blended with Jet-A fuel in turbo engines, aiming to assess its viability as a sustainable aviation fuel (SAF). The research involves the experimental testing of various blends, ranging from low to high concentrations of n-butanol, to determine their effects on engine performance and emissions. The experimental setup includes comprehensive measurements of engine parameters such as thrust, fuel consumption rates, and exhaust gas temperatures. Emissions of sulfur dioxide (SO2), and carbon monoxide (CO) are also analyzed to evaluate environmental impacts. Key findings indicate that n-butanol/Jet-A blends can significantly enhance combustion efficiency and reduce emissions compared to conventional Jet-A fuel. Higher n-butanol concentrations lead to improved thermal efficiency and lower SO2 and CO emissions. This study underscores the potential of n-butanol as an SAF for turbo engines, highlighting its ability to mitigate environmental impacts while maintaining or improving engine performance. This research supports the feasibility of integrating n-butanol into Jet-A blends for turbo engine applications, emphasizing their role in achieving more environmentally friendly aviation operations. [ABSTRACT FROM AUTHOR]

This study explores the sorption capacity and field application of activated carbons (ACs) derived from plant residues for the remediation of oil-contaminated soils. ACs were prepared from rice husks, reed stalks, pine sawdust and wheat straw using two-stage pyrolysis and chemical activation with potassium hydroxide. The structural and physicochemical properties of these ACs were analyzed using BET surface area measurements, SEM analysis, Raman spectroscopy and FTIR spectroscopy. Sorption experiments at room temperature demonstrated that AC from rice husks (OSL) exhibited the highest sorption capacities for gasoline, kerosene and diesel fuel, with values of 9.3 g/g, 9.0 g/g and 10.1 g/g, respectively. These results are attributed to the well-developed microporous and mesoporous structures of OSL, as confirmed by SEM images and a BET surface area of 2790 m2/g. Field tests conducted at the "Zhanatalap" oil deposit showed that the ACs effectively reduced the oil content in contaminated soils from 79.2 g/kg to as low as 2.6 g/kg, achieving a purification degree of up to 67% within 16 days. This study highlights the critical role of structural properties, such as porosity and graphitization degree, in enhancing the sorption efficiency of ACs. [ABSTRACT FROM AUTHOR]

Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to structural simplification of the reciprocating piston internal combustion engines under a micro space constraint but has not been adequately verified at the millimeter scale. The study used a millimeter-scale HCCI reciprocating piston internal combustion engine fueled by a mixture of kerosene, ether, castor oil, and isopropyl nitrate for combustion investigation. The test engine with a displacement of 0.547 cc is the smallest reciprocating piston internal combustion engine known to have undergone in-cylinder combustion diagnosis. It is observed that the HCCI combustion mode at the millimeter scale can realize stable combustion with excellent cooperation for the thermodynamic cycle under appropriate structural and operating conditions, which is essentially not inferior to those in conventional-sized reciprocating piston internal combustion engines. This finding helps the next step of scaling down reciprocating piston internal combustion engines. [ABSTRACT FROM AUTHOR]

In experiments on a dual-mode scramjet combustor utilizing kerosene fuel, closed-loop control tests are conducted using the resistance-heated pure air supersonic combustion test equipment with the wall pressure or the pressure ratio as controlled parameters. The results revealed faster response to changes in the kerosene flow rate when controlling the wall pressure downstream of the injection point as compared to the near injection point. The closed-loop control scheme achieved objectives with the error smaller than 2% for various parameters, demonstrating the repeatability and the broad applicability. During the hydrogen-single combustion phase, the combustor operated in the supersonic combustion mode, while during the mixed combustion phase of hydrogen and kerosene, the combustor operated in the subsonic combustion mode. The backpressure caused by combustion affects the isolator inlet, and during the kerosene-single combustion phase, the combustor operates in the subsonic combustion mode. [ABSTRACT FROM AUTHOR]

Aviation kerosene is a high-density, high-calorific value fuel widely used in high-velocity oxygen fuel (HVOF) thermal spraying. However, incomplete combustion of aviation kerosene generates CO2, CO, and unburned hydrocarbons, which are not conducive to sustainable development for industry. Research on new HVOF processes using clean fuels is significant for energy conservation and emission reduction. In this study, a two-dimensional numerical model of JP-8000 spray gun flow field was established based on the computational fluid dynamics method, and the ethanol was blended into aviation kerosene fuel to reduce carbon emissions during spraying. Ethanol-kerosene premixed fuel and WC-12Co particles were injected into spray gun in discrete phase form. The KHRT method and O 'Rourke method in the discrete phase model were used to deal with the breakup and coalescence of fuel droplets. Lagrange tracking method was used to capture the flight trajectory of fuel droplets and sprayed particles, and the gas–liquid–solid coupling calculation of spraying flow field was realized. The results show that adding ethanol to aviation kerosene fuel can effectively reduce CO2 emissions. When the ethanol proportion is 10%, CO2 emissions decrease by nearly 30%. Ethanol pyrolysis leads to a slight increase in CO emissions, which can be effectively reduced by appropriately increasing the oxygen/fuel ratio. This study provides an important theoretical basis for the spraying practice of HVOF mixed fuel for energy saving and environmental protection and offers new insights for further optimizing the spraying process. [ABSTRACT FROM AUTHOR]

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In this work, for the first time, various surfactants such as oleic acid, oleylamine, Tween 20 and Span 20 were used as static dissipating additives (SDA) for kerosene fuel to enhance their electrical conductivity. The ability of the surfactant dispersed kerosene fuel to store, transport, and process was revealed in terms of process safety parameters such as electrical conductivity, retention period, and viscosity. The results indicated an enhancement of the electrical conductivity of the kerosene fuel up to 1689 pS/m for a 500 ppm addition of surfactants. The surfactant dispersed fuel was measured for electrical conductivity with a varying temperature range from 30 to 70 °C. The addition of 0.05% by weight surfactants increased the viscosity of the kerosene fuel by 20.7%, however, without degrading the fuel quality. A laudable reduction in the retention period of 10 days was also observed. This study revealed that the surfactants selected in this study are found to be potential additives to reduce the ignition hazards of kerosene fuels. [ABSTRACT FROM AUTHOR]

Relative humidity with respect to ice (RH i) is a key variable in the formation of cirrus clouds and contrails. We document its probability density function (PDF) using long-term Measurements of Ozone, Water Vapour, Carbon Monoxide and Nitrogen Oxides by In-Service Airbus Aircraft (MOZAIC) and the In-service Aircraft for a Global Observing System (IAGOS) observations over the period 1995–2022 in the upper troposphere (UT) and the lower stratosphere (LS) between 325 and 175 hPa. The characteristics of the RH i PDF differ in the UT and in the LS of the high-latitude regions (HLs) and mid-latitude regions (MLs) of the Northern Hemisphere. In the LS, this PDF decreases exponentially with increasing RH i. In the UT, it first increases exponentially in subsaturated conditions and then decreases exponentially in supersaturated conditions. Because of these different behaviors, the PDF for the combined UT and LS is bimodal. In contrast to the HLs and the MLs, the RH i PDF in the tropical troposphere decreases exponentially with increasing RH i. The different forms of PDF, in the tropics and in the higher-latitude regions, lead to a global PDF of RH i in subsaturated tropospheric conditions that is almost uniform. These findings invite caution when using MOZAIC and IAGOS measurements to calibrate large-scale simulations of RH i. The variability in RH i properties associated with that of temperature also has implications for the formation of contrails. We examined the impact of switching fuel (from kerosene to bioethanol or liquid hydrogen) on the frequency of contrail formation using the Schmidt–Appleman criterion. We show that bioethanol and, to a larger extent, liquid hydrogen would produce more contrails. The impact of a potential change from kerosene to these alternative fuels decreases with decreasing pressure but increases when moving from the higher latitudes of the Northern Hemisphere to the tropics. Finally, we emphasize that investigations of the impact on contrail occurrence frequency as a result of switching from fossil kerosene to more sustainable fuels must be carried out in various meteorological conditions. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impact of diesel and kerosene on the transient processes occurring in a micro-turbojet aviation engine. The experiments were conducted under two distinct ambient temperature conditions, 0 and 20 °C. Specifically, we analyzed the starting phase of the micro-engine while operating with kerosene and diesel at both ambient temperature settings. Comparative graphs were generated, and the starting time was meticulously examined. Subsequently, we constructed performance maps for the engine using both fuels and across the two ambient temperature scenarios. We then executed a transient process, comprising sudden acceleration and deceleration, under the aforementioned ambient temperature conditions and with both fuels. The fluctuations in temperature within the combustion chamber, thrust force, and fuel consumption are presented for both rapid acceleration and deceleration events. Furthermore, we conducted comparisons between the thrust force, fuel flow rate, combustion chamber temperature, and specific fuel consumption for the two fuels tested and under the two ambient temperature conditions, both during idle and at higher engine regimes. In the idle regime at 0 °C, the kerosene flow is about 0.78% higher than diesel, with the kerosene thrust approximately 1.92% greater. At 20 °C, the kerosene consumption rises by roughly 5.56% compared to diesel, while the thrust increases by about 1.38%. It was observed that at the maximum operating regime, at 0 °C, the kerosene flow exceeds diesel by around 6%, with the kerosene thrust slightly higher, by about 0.63%. At 20 °C, the kerosene consumption rises by roughly 13.19% compared to diesel, while the thrust increases by about 5.91%. In higher regimes, the kerosene consumption surpasses diesel, but the thrust increase is not significant. Thus, diesel's use as a fuel for the microturbo engine is justified due to its lower consumption at both 0 °C and 20 °C. [ABSTRACT FROM AUTHOR]

The application of hydrogen for fuel enrichment and blending has recently gained importance. The sustainability and performance enhancement through hydrogen addition in flameless combustion mode for liquid fuels needs further investigation to enhance our understanding. Therefore, the present study reports the effect of hydrogen addition on the flameless combustion of a kerosene-fired 30 kW swirl combustor with hydrogen addition. A divergence-shaped conical combustor with tangential air injection and asymmetric fuel injection scheme is adopted. The liquid fuel was injected using a solid-cone swirl nozzle with 34 μm Sauter Mean Diameter. The hydrogen addition was varied from 0 to 20% on a thermal input basis, and the thermal input of liquid fuel was maintained at a 30 kW level. Computational studies helped understand the flow physics behavior within the combustor volume. The hydrogen addition was observed to improve the reactant dilution ratio (R dil). The maximum values of the R dil increased from 4.47 to 5.44 with hydrogen addition. Hydrogen addition further helped extend the flameless combustion regime to φ = 0.3 without any air preheating. A uniformly distributed reaction with a reduced-temperature gradient is observed with extended combustion stability limits. A marginal increase in NO x emissions was observed with hydrogen addition, albeit within permissible limits, accompanied by ∼8–20 dB reduction in acoustic emissions. [Display omitted] • Effect of H 2 addition in flameless combustion is studied with kerosene. • H 2 in flameless combustion, enhancing sustainability via wider flammability limits. • H 2 improves temperature uniformity, minimizing temperature gradients. • H 2 addition reduced the CO emissions. [ABSTRACT FROM AUTHOR]

The dynamically growing sustainable aviation fuel (SAF) industry and the implemented European policy create the need for conducting research on the actual benefits of using alternative fuels in aviation. The aim of this research was to assess the impact of HEFA (hydroprocessed esters and fatty acids) fuel on the particulate matter emission indicators of an aircraft engine. This article presents the results of the measurements of particle emissions from a jet engine fueled by a blend of aviation kerosene and HEFA fuel (with HEFA content at 5%, 20%, and 30% by volume). A positive effect of HEFA on both the number and mass indices of particles was observed. The use of SAF fuel led to a reduction in the particulate number index by 90% and the particulate mass index by 75%. The Particle Number Emission Index (EIN) for an engine fueled with Jet A-1 exhibited values ranging from 5.23 × 1016 to 1.33 × 1017 particles per kilogram. The use of HEFA fuel (30% content) allowed for a reduction in the EIN to the range of 2.83 × 1015 to 1.04 × 1016 particles per kilogram. A detailed analysis of particle size distribution (PSD) for both the number and volume of particles was conducted. It was noted that neither the fuel composition nor the engine operating parameters significantly affected the shape of the PSD, but the use of HEFA fuel distinctly reduced the values of the number-based PSD. It was observed that the volume-based PSD had a bimodal shape, indicating a significant contribution of particles larger than 100 nm, forming the so-called soot mode. Our findings suggest that even a small amount of HEFA fuel yields satisfactory results in reducing particulate matter emissions. [ABSTRACT FROM AUTHOR]

In this numerical study, the heat transfers of two types of fuels, namely kerosene and gasoline, were studied within a wavy channel with pulsed flow. The CFD module at COMSOL Multiphysics was used in this study. Several variables were used and applied to both types of fuel and compared between them. These variables included the values of Reynolds numbers between 200 to 800, as well as several values of Strouhal Numbers between 0 to 0.25. Different variable values were also used for the wavy channel, including the wave numbers (0, 2, 4, 6, 8, 10) as well as variable values of the wave amplitude (0, 0.1, 0.2, 0.3). Through this study, it was observed that as Strouhal Numbers increase, there is an increase in the Nusselt Number value. It was also observed that as the number of waves increases, there is an improvement in the heat transfer values. The numerical results showed that the values of heat transfer improved with an increase in the amplitude of the wave.. [ABSTRACT FROM AUTHOR]

The aviation industry uses heavy hydrocarbon fuels, which release carbon-based emissions upon combustion and could suffer from flame stabilization issues due to their high Lewis numbers at lean conditions. Hydrogen is emerging as an alternative fuel which can help mitigate these issues. A viable strategy is to blend liquid hydrocarbons with hydrogen, which could strengthen the flame in positively stretched regions and help reduce carbon-based emissions. In order to investigate this, we carry out a numerical study for different blends of n-dodecane, which is a surrogate fuel for kerosene and jet fuel, with hydrogen in air. Equivalence ratios and unburnt temperatures of different blends are selected such that the laminar burning velocity remains the same. This condition allows for a more precise characterization of Lewis number effects manifested at the flame base and tip. It is found that up to 60 % addition of H 2 into n-dodecane by volume, no major difference is observable with respect to the flame stabilization process. The positively curved flame base burns weakly while the negatively curved flame tip is strengthened due to thermal diffusivity being greater than mass diffusivity. With a further increase in the percentage of hydrogen, the flame base starts to burn stronger with the flame moving closer to the flame holder. However, the flame tip does not become weak as n-dodecane continues to burn there. As positive stretch and negative curvature increase the consumption rate for H 2 and n-dodecane flames, respectively, for the blend with 95 % hydrogen and 5 % n-dodecane, a flame is observed with the flame base and the flame tip both burning strong. Overall, this demonstrates that introducing hydrogen at concentrations exceeding 60 % by volume significantly enhances flame stabilization by bringing the flame closer to the flame holder, potentially expanding flame stabilization boundaries. [Display omitted] • Addition of hydrogen into n-dodecane numerically analyzed for multi-slit flames. • Mixtures with the same burning velocity were selected for a fair comparison. • n-dodecane flames remain unaffected till 60 percent of hydrogen addition. • For higher hydrogen content, the flame base starts to burn strong due to Le < 1 effects. • The addition of hydrogen can help in the stabilization of n-dodecane flames. [ABSTRACT FROM AUTHOR]

In this CFD study conducted with the geometry of a mini gas turbine engine using kerosene as fuel, colorless distributed combustion conditions were achieved by increasing the N 2 ratio in the air. Then, H 2 was added to the kerosene fuel in order to increase the combustion performance and the combustion chamber temperature distributions, NO x , CO, and CO 2 values were examined. In the simulations using the simplified GTM-120 geometry, the combustion chamber outlet temperatures at 80 k, 100 k, and 120 k rpm were compared with the experimental results in the literature by changing the ratio of fuel and air for the validation study. Standard k-ε and Discrete Ordinates were chosen for turbulence and radiation models, respectively. In the study conducted with the non-premixed combustion model, simulations were made at O 2 rates of 21%, 19%, 17%, and 15% for the formation of colorless distributed combustion conditions. For enrichment with hydrogen, H 2 was added from 0% to 50% with 10% increments. HEF (Hydrogen energy fraction) has been used as the hydrogen addition rate. In light of the analyses made, it was seen that the colorless distributed combustion regime reduced the flame temperature from 2292 K to 1912 K and the NOx amount from 2.85 ppm to 0.0086 ppm. On the other hand, it is seen that this regime increased the CO emissions from 6.9 ppm to 38.67 ppm and the mole ratio of CO 2 from 6.25% to 6.94%. It was observed that these findings prepared the ground for increasing the amount of hydrogen in the fuel, which increases the flame temperature and, accordingly, NO x emissions. By adding 50% H 2 to kerosene under standard atmospheric conditions, the average NO x emission at the combustion chamber outlet increased from 2.85 ppm to 7.97 ppm, while the average CO emission decreased from 6.9 ppm to 1.08 ppm. As a matter of fact, by the addition of 50% H 2 to the kerosene with air that contains 15% O 2 , which is the most extreme combustion situation in this study, the flame temperature decreased to 1912 K, and NO x rose to 0.0713 ppm. However, the CO emissions at the combustion chamber outlet decreased to 1.83 ppm and the CO 2 ratio to 3.48%. Thus, with this study, it has become possible to use hydrogen as an alternative fuel in a real engine geometry by using CDC and hydrogen enrichment together, both in terms of pollutant emissions and combustion performance. • Colorless distributed combustion has been studied in a mini jet engine. • The effect of hydrogen addition on pollutant emissions was investigated. • Uniform thermal fields in the combustion chamber and ultra-low NO x emissions at the outlet have been obtained under CDC conditions. • In combustion with pure kerosene under CDC conditions, the mean NO x 0.0086 ppm and the mean CO 38.67 ppm were found at the combustion chamber outlet. • It has been observed that the addition of hydrogen reduces CO and CO 2 emissions. • By adding 50% H 2 to the kerosene with air containing 15% O 2 , the mean NO x 0.0713 ppm and mean CO 1.83 ppm were found at the combustion chamber outlet. [ABSTRACT FROM AUTHOR]

A comprehensive CFD model is developed to predict soot for a turbulent kerosene-air diffusion flame. The method of moments (MOM) soot model has better prediction capability with meaningful soot behavioral predictions than semi-empirical models. The coupled model is primarily validated with experimental measurements from the literature in the form of major species concentration, flame temperature, and soot volume fraction. A surrogate mix comprising 80% n-decane and 20% toluene on a liquid volume basis constitutes kerosene fuel. The 20% aromatic content is able to reproduce the sooting behavior with considerable accuracy. The model can replicate CO, CO2, CH4, C2H2, C2H4, and C6H6 concentrations, flame temperature, soot volume fraction, and soot aggregation parameters for a laminar JetA-1 flame at atmospheric pressure. The reproduction of flame temperature and major species concentrations for a laminar kerosene flame validates the applicability of the gas-phase kinetic mechanism and PAH formation pathway for the reacting flow system. The model also performs appreciably for measurements of a turbulent kerosene flame at higher operating pressures up to 6.44 bar. The peak soot volume fraction matches significantly well with the measurements for all the flames. The predicted peak soot volume fractions are 8.8, 27.3, 68, and 82 ppm compared to measured values of 9.3, 28.3, 63, and 67 ppm at pressures 1, 2.7, 4.81, and 6.44 bar, respectively. However, the location of the peak soot has a slight discrepancy at low pressures till 2.7 bar, showing the predicted peak earlier compared to a later appearance in the measurements. The simulated peak flame temperatures are 1377, 1393, 1412, and 1477 K as operating pressure increases from 1 to 2.7, 4.81, and 6.44 bar. The thermal absorbance from soot and species radiation plays a vital role in predicting the flame temperature. Soot radiation reduces flame temperature by ~ 500 K compared to gaseous radiation (CO2, H2O, CO, CH4, etc.), reducing approximately 100 K. The predictive soot number density, mean diameter, surface area, primary particle count in soot aggregates, and primary particle diameter carry a substantial dependency on the operating pressure. [ABSTRACT FROM AUTHOR]

Background Unclean cooking fuels (ie, polluting fuels including kerosene/paraffin, and solid fuels) are a major contributor to diseases and mortality, specifically in low- and middle-income countries. Methods This review aimed to identify potential mechanisms, public health implications, and future directions of unclean cooking fuel use and health outcomes in older adults. Results There is an expanding body of literature to demonstrate associations between unclean cooking fuel use and multiple mental and physical health outcomes in older adults. Two key mechanisms likely driving such associations include inflammation and oxidative stress. Conclusions Considering that inflammation and oxidative stress have been implicated in multiple other health conditions (eg, arthritis and osteoporosis) in addition to those investigated to date on this topic it would be prudent to continue investigation of unclean cooking fuel use and with yet to be studied health outcomes. Moreover, future research is indeed now required to identify pathways to eliminating unclean cooking fuel globally to better the health of an aging global population and to support the implementation of Sustainable Development Goal 7. [ABSTRACT FROM AUTHOR]

The lean blowout (LBO) limit is crucial for gas turbine combustor in the aero engine. The effect of atomization of liquid fuels on the LBO limit is needed to be further studied. On the other hand, the effects of atomization on the LBO limit can be neglected if gas fuels are utilized in a combustor. Thus, the comparative experiment between liquid fuel and gas fuel can be utilized to study the effects of atomization performance of liquid fuels on the LBO limit. In this paper, the LBO limit for a gas turbine combustor utilizing methane is studied experimentally. Seven kinds of combustor configurations are chosen for the experimental test. The LBO limits are obtained for all the chosen combustors. The variation of the LBO limit with the combustor configuration for both methane and aviation kerosene exhibits the similar tendency, i.e., the LBO limits utilizing methane are slightly larger than those utilizing aviation kerosene for the same combustor. Further, the atomization performance has little effects on the LBO limits for the present combustor configurations at the present operating conditions where the SMD for the fuel atomizer utilizing aviation kerosene is about 10 μm. [ABSTRACT FROM AUTHOR]

This study deals with the design of a suitable configuration of jet deflector for supersonic exhaust gases from a semi-cryogenic launch vehicle engine using computational fluid dynamics. Computational model of combustion in semi-cryogenic engine, with kerosene as fuel and liquid oxygen as oxidizer, was developed in which exhaust gases from engine were impinged on the deflector surface. Different design configurations of deflector structure, obtained by the combination of various impingement angles of 15°, 20°, 25°, 30°, and 45°, and different exit radii of 5000, 10 000, and 20 000 mm, were used in the developed computational models to analyze impingement, deflection, and associated flow properties of exhaust gases, such as acoustics, force on deflector imparted by jet, temperature, and Mach number of flow field. A new ablation model was developed based on Vieille's law to determine the amount of refractory material ablated from deflector structure for different configurations. The developed models of ablation, combustion, and flow impingement were also validated with existing literature. It was found that the configuration with 20° impingement angle and 10 000 mm exit radius had ablation, acoustics, force, and flow properties in desired limit. Furthermore, to find the optimum uplift angle for designing jet deflector, configurations with uplift angles of 0°, 5°, 15°, and 25° were studied using the computational models developed in the study. It was observed that the configuration with 20° impingement angle, 10 000 mm exit radius, and 15° uplift angle was best suited for impingement and deflection of exhaust jet from the specified semi-cryogenic engine. [ABSTRACT FROM AUTHOR]

In this study, numerical simulations based on an Eulerian-Lagrangian framework are conducted to investigate the liquid-fueled rotating detonation engine (RDE) with heterogeneous kerosene-hydrogen-air mixtures. The hydrogen addition is implemented for combustion enhancement of the liquid kerosene and helps to ignite and achieve a self-sustained two-phase rotating detonation wave (RDW). The effects of droplet evaporation at various initial droplet sizes and kerosene mass flow rates on the structure and propagation of the two-phase RDW are analyzed. Results suggest that with smaller droplet sizes, the structure of the RDW is analogous to that of a gaseous RDW, and a comparison with experimental data suggests that the estimated detonation speed and thrust performance (fuel-based specific impulse) are within the reasonable ranges. However, as the droplet size or the mass flow rate of kerosene increases, the two-phase RDW exhibits characteristic features such as the dual-front laminated structure, micro-explosions and secondary transverse waves. • Rotating detonation engines (RDEs) with a heterogenous kerosene-hydrogen-air mixture are investigated. • Numerical simulations based on an Eulerian-Lagrangian two-way coupled framework are conducted. • A dual-front rotating detonation wave (RDW) caused by droplet evaporation is explained. • Micro-explosions and secondary RDWs are captured at higher kerosene mass flow rates. [ABSTRACT FROM AUTHOR]

Addressing the burgeoning issue of polymer waste management and disposal, chemical recycling, specifically the production of highquality oil, presents an enticing solution. This research paper delves into the process of plastic waste pyrolysis, focusing on polypropylene, and thoroughly examines the physico-chemical properties of the resulting pyrolytic oil. The oils, obtained from waste plastic pyrolysis (referred to as WPPO), are then blended with kerosene and utilized as fuel for a gas turbine engine. The primary objective of this investigation is to ascertain how the blend composition influences the performance and emission parameters of the micro gas turbine. In our findings, it was observed that all tested waste plastic pyrolysis blends displayed a trend towards escalating regulated emissions such as nitrogen oxides (NOx) with an average increase of 26% for polypropylene pyrolysis oil (PPO). The emission index (EI) for carbon monoxide (CO) was found to be relatively consistent across all fuel blends tested in this study. Interestingly, when considering the thrust specific fuel consumption (TSFC) within the EI calculation, blends of aviation kerosene and plastic oil showed lower values in comparison to the pure Jet A-1 fuel. Furthermore, an augmentation in the proportion of WPPO in the blends consequently led to an elevation in the exhaust gas temperature (an average increase of 8.7% for PPO). Interestingly, the fuel efficiency of the Jet engine, expressed as TSFC, demonstrated a decrease, with an average reduction of 13.8% observed for PPO. [ABSTRACT FROM AUTHOR]

In this paper, the effects of the Tesla valve intake structure with or without bypass manifold on suppressing pressure feedback and combustion product backflow in rotating detonation engine fueled by kerosene and enriched air with 29% oxygen content are investigated, with the configuration of convergent–divergent intake without bypass manifold being used for comparison. The working range, detonation wave propagation characteristics, and propulsion performance for the three configurations are evaluated. It is found that the Tesla valve intake structure can effectively improve the suppression of pressure feedback and combustion product backflow through the diversion function of the Tesla valve bypass channel and that the addition of the bypass manifold further improves the suppression of pressure feedback. The Tesla valve intake with bypass manifold configuration has the best ability to suppress pressure feedback, with a minimum value of pressure feedback percentage of about 6.5% and a minimum value of air plenum pressure fluctuation percentage of about 6.7%. By comparison, the minimum value of pressure feedback percentage of the convergent–divergent intake without bypass manifold configuration is about 29.8%, and its minimum value of pressure feedback percentage is about 7.8%. The Tesla valve intake without bypass manifold configuration is most effective in suppressing combustion product backflow, with the effective inlet area ratio of about 95.7%. Under the same conditions, the minimum effective inlet area ratio of the convergent–divergent intake without bypass manifold configuration is about 90.2%. Ultimately, optimizing the engine structure leads to a broader working range and higher propulsion performance. The Tesla valve intake structure broadens the working range by suppressing the generation of the longitudinal pulsed detonation mode. When the bypass manifold is incorporated, some combustible reactants directly enter the rear of the combustion chamber from the head of the chamber, and the working range is reduced. Compared with the convergent–divergent intake without bypass manifold configuration, the working range of the Tesla valve intake with bypass manifold configuration is widened by 383.3%, and that of the without bypass manifold configuration by 700%. Both the Tesla valve intake and bypass manifold increase the strength of detonation waves and improve propulsion performance. The Tesla valve intake with bypass manifold configuration has the highest specific thrust, at about 90.1 N s3/(kg·m). This is increased by an average of 10% compared with the Tesla valve intake without bypass manifold configuration, and by an average of 30.1% compared with the convergent–divergent intake configuration. • Tesla valve inlet and bypass manifold are used to suppress feedback. • Two quantitative evaluation parameters of pressure feedback are established. • The degree of combustion product backflow is evaluated. • The optimized structure can effectively improve the propulsion performance. [ABSTRACT FROM AUTHOR]

By 2050, aviation-related carbon emissions are expected to quadruple to over 3000 million tonnes of carbon dioxide, so finding sustainable alternative solutions to minimise pollution is a key scientific challenge. Aviation gasoline and kerosene are currently used to power most jet engines. While battery-powered planes and planes that could utilise a cleaner fuel, such as hydrogen, are possible, the time scale required to improve and implement these technologies is distant, with air fleet turnover taking some 30 years. Existing jet engines could be modified to run on biodiesel, and considering the close similarity in fuel density to kerosene, could be a less disruptive approach to the industry. The sheer volume of biodiesel required remains a challenge, and certainly, using plant-derived oils grown on arable land is not acceptable, as it competes with food production. However, high-lipid-yielding microalgae (where productivity is an order of magnitude greater than oilseeds), grown on marginal land, such as desert or semi-desert areas of the world, could be possible. Indeed, to replace 30% of fossil fuel with algal-derived biodiesel would require 11,345 km2 of land. Biodiesel preparation is well understood, but what is lacking is proven technology aimed at optimising microalgal production of oil at a much larger scale. Here, a synergic review of the current state-of-the-art in algal production, that includes strain selection, possible production sites, culturing costs, and harvesting to identify the bottlenecks in meeting the ASTM specifications for the aviation industry, is presented. [ABSTRACT FROM AUTHOR]

The search for renewable, affordable energy alternatives has gained momentum in light of dwindling fossil fuel reserves. Biofuels, particularly those derived from plant sources, present a viable solution to both the energy crisis and environmental degradation. This study focuses on the implementation of olive oil methyl ester (OME) biofuel in micro gas turbine engines. Biofuel blends, with volumetric OME concentrations ranging from 20% to 80% in standard kerosene, were prepared and tested on a GT 85-2-H micro gas turbine unit. The engine's performance and exhaust emissions were evaluated under two different operational parameters: constant speed and constant load. The use of an 80% OME biofuel blend resulted in an 8.7% reduction in overall efficiency and a 13.1% increase in specific fuel consumption (SFC) under an 80% load. However, it also led to a significant improvement in exhaust emissions, with reductions of 28.8%, 39%, and 33.8% recorded for carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx), respectively. Similarly, under a constant speed test at 20000 rpm, an 80% OME blend caused a 10.5% reduction in overall efficiency and a 13.6% increase in SFC. Nevertheless, the same blend improved the CO, HC, and NOx emissions by 38%, 41.4%, and 36%, respectively. The findings confirm the potential of OME as a biofuel in micro gas turbine engines, underlining its effectiveness in reducing harmful emissions. This research emphasizes the feasibility of biofuels derived from olive oil in addressing future energy demands while mitigating environmental impact. [ABSTRACT FROM AUTHOR]

Studies of the influence of hydrocarbon rocket fuel kerosene T-1 on the physical and geochemical properties were carried out in laboratory circumstances on different types of soils: brown semi-desert soil designated as zone (U-25) located in Central Kazakhstan, mountainous brown desert soil zone (U-30) located in East Kazakhstan, and a model soil standard (control soil). The soil was treated with various concentrations (0.002–150.0 g/kg) of hydrocarbon rocket fuel kerosene T-1, while the contact time was 3, 10, and 30 days. Pollution with kerosene T-1 in concentrations 5.0–15.0 g/kg affects the hydraulic characteristics of soils from the U-25 zone, and the filtration rate decreases by 4–5 times. For the mountainous brown desert soil from the U-30 zone, the concentration of kerosene up to 15.0 g/kg does not affect the mechanical composition of the soil, as well as the availability of the main nutrients (potassium, phosphorus, nitrogen). According to the mechanical composition, both soils belong to medium loamy soils. It has been established that when soil is contaminated from the U-25 zone in concentrations 15.0–150.0 g/kg, the fraction from 1.0 to 0.05 mm increases by 4–5%, and the silty and clay fractions in the soil decrease. [ABSTRACT FROM AUTHOR]

Present work performs a comparative study of two medium-range commercial jets with future airframe and propulsion technologies powered by hydrogen and kerosene fuel to achieve a substantial reduction in overall aviation emissions. The study aims to investigate the cumulative effect of different energy networks combined with airframe efficiency gains achieved by aircraft-related technologies to suggest a better option for the potential next-generation commercial aircraft similar to the Airbus A320. Advanced airframe and engine technologies include laminar flow control, active load alleviation, new materials and structures, and ultra-high bypass ratio turbofan engines. Two aircraft with hydrogen and kerosene propulsion systems were sized to compare their performance characteristics, equivalent CO2 emission, and direct operating costs. The design was performed using a multi-fidelity approach and included the effects of future airframe technologies and the hydrogen propulsion system. The design comparison showed a significant contribution of airframe and propulsion technologies in achieving more environmentally friendly aircraft. The green hydrogen option showed a 41–63% reduction in overall emissions compared to the kerosene aircraft depending on flight conditions while the blue hydrogen variant achieved a 21–26% reduction level. A rather optimistic price scenario shall be met to enable an operational benefit of green hydrogen while the blue hydrogen variant has more potential of being economically acceptable by the market. In circumstances when operating costs drive the decision-making more than emissions, kerosene may be a more favorable option as a compromise between emission and costs, given the positive effect of airframe and propulsion technologies. [ABSTRACT FROM AUTHOR]

In this study, a large-scale kerosene-fueled oblique detonation engine with a design point of Mach 10 is proposed. The flow combustion characteristics and the propulsive performance considering the wall viscous drag of the detonation engine are investigated using numerical simulation methods with a detailed combustion mechanism. The accuracy of the numerical results is verified by comparing it with the detonation wave pole curve of kerosene fuel. The result demonstrates that the combined injection method consisting of wall and center-strut injectors can meet the requirements of fuel mixing in the oblique detonation engine and a stabilized oblique detonation wave is successfully formed in the combustor. The decrease in the fuel equivalent ratio leads to an increase in the non-uniformity of the temperature distribution behind the detonation wave and the decrease in the wave angle. The advantage of the oblique detonation wave in hypersonic propulsion is its easy adjustment and can achieve flight over a wide-speed range. The combustion heat release behind the wave is closer to the upper part of the wave surface as the incoming Mach number decreases. The oblique detonation engine proposed in this study can still generate stable net specific impulse at non-design point flow Mach numbers. The net specific impulse can reach 715 s at a non-design point speed of Mach 8. It proves the feasibility of wide-speed range flight applications of oblique detonation engines. [ABSTRACT FROM AUTHOR]

Catalysts play a vital role in petroleum and chemical reactions. Intensified concerns for cleaner air with strict environmental regulations on sulfur content in addition to meet economic requirements have generated significant interests for the development of more efficient and innovative oxidative catalysts recently. In this study, a novel homemade nano catalyst (manganese oxide (MnO2) over tin (IV) oxide (SnO2)) was used for the first time as an effective catalyst in removing dibenzothiophene (DBT) from kerosene fuel using hydrogen peroxide (H2O2) as oxidant in catalytic oxidative-extractive desulfurization process (OEDS). The catalyst was prepared by impregnation method with various amount of MnO2 loaded on SnO2. The oxidation step was carried out at different operating parameters such as reaction temperature and reaction time in batch reactor. The extractive desulfurization step was performed by using acetonitrile as solvent under several operating conditions (agitation speed and mixing time). The activity of MnO2/SnO2 catalyst in removing various sulfur compounds from kerosene fuel at the best operating conditions was investigated in this work. The results of the catalyst characterization proved that a high dispersion of MnO2 over the SnO2 was obtained. The experiments showed that the highest DBT and various sulfur compounds removal efficiency from kerosene fuel under the best operating conditions (oxidation: 5% MnO2/SnO2, reaction temperature of 75 °C, and reaction time of 100 min, extraction: acetonitrile, agitation speed of 900 rpm, and mixing time of 30 min) via the catalytic oxidative-extractive desulfurization process was 92.4 and 91.2%, respectively. Also, the MnO2/SnO2 catalyst activity was studied after six consecutive oxidation cycles at the best operating conditions, and the catalyst prove satisfactory stability in terms of sulfur compounds removal. After that, the spent catalyst were regenerated by utilizing different solvents (methanol, ethanol and iso-octane), and the experimental data explained that iso-octane achieved highest regeneration efficiency. [ABSTRACT FROM AUTHOR]

Self-immolation is the act of setting fire to oneself. Recent spikes in self-immolation events have been noticed in the Arab world, specifically in the aftermath of the Arab Spring in 2011. We aimed to examine the literature assessing the characteristics and patterns of suicide by self-immolation in the Arab world. We registered our systematic review in Prospero. We searched PubMed, Medline, PsycInfo, Embase, and Scopus databases from inception until 9 July 2022, along with other sources, following the PRISMA 2020 guidelines. We collected relevant articles tackling suicide by self-immolation in the Arab world via title and abstract screening followed by full-text screening. We then conducted a narrative synthesis of the results. Out of 326 records from databases and 17 additional records identified through other sources, 31 articles (27 quantitative and 4 qualitative) were included. The studies came from Iraq (n = 16), Tunisia (n = 6), Kingdom of Saudi Arabia (n = 3), Jordan (n = 2), Libya (n = 2), Bahrain (n = 1), and Egypt (n = 1). The quantitative studies had a sample size ranging from 22 to 600 self-inflicted burn victims. Studies showed that self-immolators were mostly married women with low educational level and low socioeconomic status. Self-immolation was more likely to happen at home, usually following marital conflicts. Kerosene was the accelerant used the most. Depression was the most comorbid mental health diagnosis. Studies highlighted that self-immolation was being increasignly used as a form of protest. Self-immolation is not uncommon in the Arab world. Specific interventions directed at the population at risk are warranted. • Self-immolation victims were commonly married females. • The most common triggers for self-immolation were familial and marital conflicts. • Either Kerosene or fuel was commonly used as accelerants. • The prevalence of mental illness among victims ranged from 5 % to 40 %. • The most reported psychiatric diagnoses were depression and schizophrenia. [ABSTRACT FROM AUTHOR]

Spark ignition (SI) engines fueled with kerosene have broad application prospects in unmanned aviation vehicles. The knock phenomenon of kerosene in SI engines is a huge challenge, leading to a much lower power output than gasoline engines. In this context, the combustion characteristics of kerosene blending with hydrogen are analyzed numerically regarding the working conditions of an SI engine. First, the ignition delay time of a kerosene/hydrogen mixture is estimated for temperatures of 600–1000 K and pressures of 15–35 bar using the Tay mechanism. The effects of hydrogen addition are evaluated with a ratio of 0–0.4. The sensitivities of the main reactions that affect the ignition delay time are discussed. Then, the laminar flame speed is predicted using the HYCHEM-SK mechanism, and the effects of hydrogen addition on the net reaction rates of the main reactions are analyzed. The results indicate that the ignition delay time is shortened and the laminar flame speed is increased as the hydrogen addition ratio rises. Meanwhile, the ignition delay time decreases except for the NTC range, and the laminar flame speed increases evidently as the temperature rises. In addition, the ignition delay time decreases obviously as the pressure increases with a temperature greater than 750 K. However, the laminar flame speed declines at 600 K and 800 K, while an opposite trend exhibits at 1000 K as the pressure rises. The laminar flame speed increases by 23.85–24.82%, while the ignition delay time only decreases by 4.02–3.59% at 1000 K as the hydrogen addition ratio rises from 0 to 0.4, which will be beneficial for knock suppression. [ABSTRACT FROM AUTHOR]