Jet Fuel Research Articles

Jet fuel oxidation on conventionally and additively manufactured metallic tubes

In the aviation industry, jet fuel is a propellant as well as a coolant. At elevated temperatures, the jet fuel experiences significant thermal stresses, which leads to the oxidation of hydrocarbons when exposed to the heat exchanger walls. As a result, undesirable insoluble carbon deposits on the internal heat exchanger walls impede the effectiveness of the heat exchanger and the aircraft fuel circulatory system, compromising aircraft safety and performance. Here, we study the jet fuel fouling behavior on additively manufactured tubes created using stainless steel, aluminum alloy, titanium, and Inconel, during autoxidation at elevated temperatures. Additively manufactured materials are tested due to their numerous potential benefits for the aerospace industry, which include design flexibility for the creation of complex and optimized parts that enhance performance and aerodynamics. Experiments were conducted using a fuel-fouling open loop system based on the Jet Fuel Thermal Oxidation Test (JFTOT). Scanning electron microscopy and characterization of the internal surface of the tubes showed that the jet fuel reacts differently with different metals and alloys. Comparisons were made with traditionally manufactured materials and benchmarked with the performance of bare copper tubes. We show that additively manufactured tubes were more prone to fuel fouling due to the larger inherent roughness associated with the additive manufacturing process. We show that applying a thin layer of commercially available Silcolloy 2000 coating onto the internal surface minimizes jet fuel degradation significantly. Our work helps to enable the application of additive manufacturing for aircraft thermal management component manufacture by alleviating concerns related to fuel blockage and performance deterioration stemming from surface deposition.

Interpretable machine learning for predicting the derived cetane number of jet fuels using compact TD-NMR

Interpretable machine learning for predicting the derived cetane number of jet fuels using compact TD-NMR

Comprehensive accurate prediction of critical jet fuel properties with multiple machine learning models

Quantitative structure–property relationship (QSPR) model development driven by emerging machine learning (ML) shows promise for accelerating design and preparation of jet fuels with complex hydrocarbon compositions. In this work, we collected 104 jet fuels from different refineries, determined the detailed components of the fuel composition, and tested the fuel properties (density, viscosity, net heat of combustion, freezing point and flash point) using standard methods to form a database of molecule structure/composition and properties. Subsequently, six mainstream ML algorithms were adopted to establish the QSPR models, in which the prediction accuracy of the best ML models for each property is improved to above 0.93. Finally, the best ML property models are applied to predict unseen RP-3 fuels, and all prediction errors are within acceptable limits. This effort not only provides valuable data for the construction of the jet fuel database, but also provides tools for predicting its critical properties.

Facivitalis istanbulensis gen. nov., sp. nov., a novel member of the family Sphingomonadaceae with the potential for aromatic-degradation isolated from Jet A1 fuel.

A novel gram-stain-indeterminate, rod-shaped, endospore-forming, motile, aerobic bacterium, designated JETA1-E2T, was isolated from aircraft fuel Jet A1 sample. The strain showed high pairwise similarity values of partial 16S rRNA gene sequences to Sphingomonas paucimobilis (MT367853) (99.42%), Sphingomonas sanguinis (MF319771) (99.34%), and Sphingomonas pseudosanguinis (HE716953) (99.27%) within the family Sphingomonadaceae. However, API test results revealed that the strain JETA1-E2T differed from these type strains. The phylogenetic tree based on the whole genome and the phylogenomic tree generated with the UBCG tool showed that the strain JETA1-E2T formed a distinct monophyletic clade within the family Sphingomonadaceae, and clustered distantly with the genera Sphingomonas and Sphingobium. The predominant respiratory quinone is Q-10. The major fatty acids are C16:0 and summed feature 8 (C18:1ω7c and/or C18:1ω6c). C19:0 is present in small amounts. The polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, aminophospholipid, unidentified glycolipid, and two unidentified sphingoglycolipids. The only polyamine is putrescine in minor amounts. The DNA G + C content of the type strain is 66.5mol%. Several unique genes in the strain JETA1-E2T may contribute to fight against various stressors, virulence and pathogenicity, as well as survival in challenging conditions. The strain JETA1-E2T contains 100 of the characterised proteins available in the HADEG database of which 58% of these are involved in metabolic process of aromatics degradation. The findings indicate that the strain JETA1-E2T has the potential to metabolise hydrocarbons such as fuel, especially aromatic compounds. Based on the results of polyphasic taxonomic analyses, the strain JETA1-E2T represents a novel species in a new genus in the family Sphingomonadaceae for which the name Facivitalis istanbulensis gen. nov., sp. nov. is proposed. The type strain of Facivitalis istanbulensis is JETA1-E2T (DSM 117971T = LMG 33634T = KUEN 1206 (B) F3-1-1T).

Elucidating high-pressure chemistry in acetylene oxidation: Jet-stirred reactor experiments, pressure effects, and kinetic interpretation

Acetylene plays a crucial role as an intermediate in the combustion of complex hydrocarbons, such as, e.g., jet fuels. In this study, high-pressure acetylene oxidation has been investigated by a combination of kinetic and experimental methods using a jet-stirred reactor (JSR) in the range of 497–910 K at p = 24 atm. The study covered three fuel-equivalence ratios: φ = 0.5 (fuel-lean), φ = 1.0 (stoichiometric), and φ = 3.0 (fuel-rich). Mole fraction profiles of 10 species, including CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, CH3OH, CH3CHO, and C3H4O, were identified and quantified using gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). A kinetic model for describing the high-pressure chemistry of acetylene oxidation is proposed, which well characterizes important experimental findings, such as the fuel oxidation reactivity and the speciation of crucial products. At high pressures (p = 24 atm), acetylene exhibits a higher fuel consumption than at lower pressures (p = 1 and 12 atm) because of the increased sensitivity of dehydrogenation reactions by OH radicals accelerating the oxidation of the fuel at low temperatures. Furthermore, fuel-specific intermediates are observed, including acetaldehyde, propanal, small alkanes, and alkenes. These species mainly result from H-abstraction reactions by OH following O2-addition reactions from triple carbon bond moieties in acetylene. The formation of further products, such as carbon monoxide and carbon dioxide, is closely related to the consumption of these fuel-specific species. In particular, the formation of aromatics, such as e.g., benzene and toluene, are detected at trace levels in the current experiments due to the rapid formation and decomposition process occurring at high pressures. By analyzing the distinct kinetic behavior, it was found that acetylene was almost completely depleted at higher system pressure (p = 24 atm). Some intermediates are rather active and can react with O2 and peroxides. Consequently, the high-pressure oxidation of acetylene mainly proceeds along the pathway of CC → CHCHOH → HOCHO/OCHCHO → CO → CO2 at the high-pressure chemistry (p = 24 atm). Overall, this study provides valuable insights into the pressure-dependent combustion behavior of acetylene and its implications for optimizing jet fuel combustion processes.

Hydrodeoxygenation of Isoeugenol-Derived Model Compound over Carbon-Supported Pt and Pt-SnS Catalysts for the Production of Sustainable Jet Fuel.

This study focuses on the sustainable production of bio-jet fuel through the catalytic hydrodeoxygenation (HDO) of isoeugenol (IE). Sucrose-based activated carbon supported bimetallic Platinum-Tin metal sulphides (PtO-SnS/AC) catalyst was prepared for HDO process. Physicochemical properties of catalysts with different spraying synthesis methods (in situ and ex situ metal doping) and Pt loading (0.1-1.0 %) were further investigated. The PtO-SnS/AC catalysts were characterised using various techniques such as X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA). Both HRTEM and FESEM results show the successful preparation of a spherical nanoparticles doped over activated carbon, and Pt was dispersed on the outer shell of the particles. The catalytic HDO of IE was evaluated in a batch system and showed a high yield and conversion as follows: IE conversion of 100 %, liquid-phase mass balance of 95.92 %, dihydroeugenol (DH) conversion of 99.32 %, propylcyclohexane (PCH) yield of 88.94 % and 2-methoxy-4-propylcyclohexanol (HYD) yield of 76.19 %. Moreover, the PtO-SnS/AC catalyst exhibited high reusability with low metal leaching and high coke resistance for 10 cycles. The catalyst was evaluated in a continuous flow reactor for 100 h at different reaction temperatures, and interestingly, the catalyst showed low deactivation with a high half-time.

Combustion kinetics of alternative fuels, Part-IV: Extending reaction mechanism “DLR Concise” to include oxygenates components

In our previous work on hydrocarbons (Kathrotia et al., Fuel 2021;302:120736) and jet fuels (Kathrotia et al., Fuel 2021;302:120737) the molecular fuel composition was shown to be an important aspect of understanding the fuel combustion chemistry and, more importantly, the emission behavior. In this extension, we elaborate our high-temperature jet fuel surrogate reaction mechanism (referred hereafter as DLR Concise) to include the chemical class of oxygenated hydrocarbons for transportation fuels. These oxygen containing species have been widely investigated in ground transportation fuels. With DLR Concise we aim for a flexible reaction model for alternative fuel surrogates; a single reaction model with the target application to both aviation- as well as transportation-fuels.The main focus of this work is to describe the reaction kinetics of oxymethylene ethers (OMEx, x = 0–5) in low to high temperatures. OMEs are promising alternative fuels that can be derived from a variety of sustainable sources. The absence or reduction of C-C bonds makes them attractive for the reduction of soot precursors and soot emissions. The reaction model of OMEs presented in this work is extensively validated against wide-ranging experiments both in-house and from literature. The main purpose of the DLR Concise is to provide a reaction mechanism with a large degree in flexibility to simulate various fuel surrogates (existing and new) and predict pollutants for the fuel assessment based on fuel molecular structure.A comprehensive model validation as well as new in-house experimental data set on C1-C4 alcohols and primary reference fuel (PRF90) measured in high-temperature flow reactor is available as supplemental material.

Within-chain parallelization-Giving Stan Jet Fuel for population modeling in pharmacometrics.

Stan is a powerful probabilistic programming language designed mainly for Bayesian data analysis. Torsten is a collection of Stan functions that handles the events (e.g., dosing events) and solves the ODE systems that are frequently present in pharmacometric models. To perform a Bayesian data analysis, most models in pharmacometrics require Markov Chain Monte Carlo (MCMC) methods to sample from the posterior distribution. However, MCMC is computationally expensive and can be time-consuming, enough so that people will often forgo Bayesian methods for a more traditional approach. This paper shows how to speed up the sampling process in Stan by within-chain parallelization through both multi-threading using Stan's reduce_sum() function and multi-processing using Torsten's group ODE solver. Both methods show substantial reductions in the time necessary to sufficiently sample from the posterior distribution compared with a basic approach with no within-chain parallelization.

A Rapid Analysis Method for Determination of Hydrocarbon Types in Aviation Turbine Fuel by Gas Chromatography-Mass Spectrometry.

A rapid analysis method for determination of hydrocarbon types in aviation turbine fuel was investigated in this study. A kind of reversible adsorption material packed as an unsaturated trap was used to separate saturated hydrocarbons and unsaturated hydrocarbons in the GC-MS system. No manual process or organic reagent was needed during the entire analysis process. The contents of 13 kinds of hydrocarbons, including paraffins, monocycloparaffins, dicycloparaffins, tricycloparaffins, monoolefins, cycloolefins, alkylbenzenes, CnH2n-8 aromatics, CnH2n-10 aromatics, naphthalenes, CnH2n-14 aromatics, CnH2n-16 aromatics, and CnH2n-18 aromatics were calculated by the characteristic mass fragments detected by MS with the modified matrices of ASTM D2425. The overall analysis time was less than 10 min. The precision of this test method has been conducted with 8 laboratories attended and 16 samples analyzed. The performance of this new method was demonstrated by comparing the results tested by ASTM D1319, ASTM D2425, and ASTM D6379. This rapid analysis method can provide hydrocarbon compositions of aviation turbine fuels or other liquid hydrocarbon samples within the same distillation range.

Comparative Analysis of Performance and Exhaust Emissions from Jet A1 Blends with Various Aviation Biofuels

The aviation industry is a significant contributor to greenhouse gas emissions. Given the growing demand for air travel and the unsustainable use of fossil fuels, it is crucial to develop and commercialize renewable fuels to reduce these emissions. Conventional jet fuels like Jet A1 release harmful pollutants such as carbon monoxide (CO) and nitrogen oxides (NOx) into the atmosphere. In contrast, biofuels offer a renewable, biodegradable, and non-toxic alternative that emits fewer pollutants, excluding NOx, and is easier to treat than fossil fuels. Due to their eco-friendly characteristics, biofuels have garnered attention in recent years. This study focuses on producing biofuels from jatropha oil and waste cooking oil. Jatropha oil, aside from its medicinal benefits such as antimicrobial and anticancer properties, can be effectively used in industrial applications, particularly for biofuel production. The production of biofuels from jatropha and waste cooking oil is of growing interest due to their environmental and economic benefits. The study investigates the production of these biofuels using appropriate catalysts under controlled experimental conditions, followed by blending the biofuels with Jet A1 fuel to achieve similar engine performance while mitigating the environmental impact of greenhouse gases from petroleum-based fuels.

Burner and Flame Transfer Matrices of Jet-Stabilized Flames: Influence of Jet Velocity and Fuel Properties

Abstract To achieve the decarbonization of electrical power generation, gas turbines need to be upgraded to combust high-hydrogen content fuels reliably. One of the main challenges in this upgrade is the burner design. A promising burner concept for a high-hydrogen fuel mixture are jet burners, which are highly flashback resistant thanks to their high bulk velocity. Due to its nonacoustically compact extension and the presence of hydrogen in the fuel mixture, new challenges arise in assessing the (thermo)acoustic response of this burner design. A burner transfer matrix (BTM) and the flame transfer function (FTF) or transfer matrix (FTM) are typically measured with the multimicrophone method (MMM) to assess the performance of new burner types in relation to thermoacoustic stability. With the switch toward hydrogen, the fuel/air mixture is significantly altered in its properties regarding the speed of sound and density, which are of fundamental importance for acoustic waves propagation and their reconstruction via the MMM, as highlighted in recent work. In this work, we extend this discussion by studying the influence of the gas composition within the burner when measuring BTMs, and its indirect effect on the assessment of FTFs. Experimentally, we achieve this by adapting the preheating temperature during the measurement of the BTM with a nonreactive mixture in order to match the speed of sound of the hydrogen–air mixture required to flow in the burner under reactive conditions. Additionally, we present an analytical model for the jet burner transfer matrix, which is validated against the experimental data. Since the BTM is fundamental for the assessment of the FTM and FTF, the propagation of the error of changing fuel mixtures in the burner is evaluated. The influence of the variation in reactant composition of the BTM on the FTM assessment is noticeable, particularly in the gain of the FTFs. Furthermore, the influence of the total mass flow and, thus, the bulk flow velocity on the FTF is analyzed.

Physiochemical View of Fuel Jet Impingement and Ignition Upon Contact with a Cylindrical Hot Surface

This study delves into ignition and flame dynamics involving a cylindrical hot surface impact. Previous studies have focused on the flat-wall hot surface interacting with fuel spray, leaving gaps in understanding the effects of cylindrical hot surfaces on fuel-air mixing and ignition. Using high-fidelity large-eddy simulations (LES), this study investigates how fluid elements, upon contacting an electronically activated glow plug structure, exhibit mixing and thermochemical properties. The analysis examines how this type of structure enhances fuel-air mixing and subsequently influences the thermochemistry behavior in conjunction with the fuel-specific combustion behavior. The study includes scenarios with free spray and non-thermal deposit cases to assess their mixing impact, alongside testing five different electric voltage inputs to study the thermally assisted ignition process. Results demonstrate that the cylindrical structure hinders flow, reducing its inertia and increasing flow residence time. Moreover, a significant Coandă effect due to the circular wall structure is identified, potentially serving as a mechanism for enhancing flame-holding. Furthermore, varying the input voltage notably affects ignition timing, revealing a non-monotonic ignition delay pattern with lower voltages. Detailed analysis highlights the critical role of negative temperature coefficient (NTC)-driven low-temperature chemistry (LTC) in the ignition process.

Investigating the oxidation characteristic of a hydro-processed bio-jet fuel: Experimental and modeling study

A rapid transition from conventional jet fuels to sustainable aviation fuels (SAFs) is imperative in order to reduce carbon emissions. Hydro-processed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK), as a type of SAF, exhibits broad applications. In this study, a new HEFA-SPK named ZH-HEFA was investigated. The fuel comprises 14% n-alkanes, 85% iso-alkanes and only 1% cycloalkanes by weight, with the majority of alkanes ranging from C9 to C17. Oxidation experiments of the fuel were conducted using an atmospheric pressure flow reactor at temperatures ranging from 550 K to 1075 K under three equivalence ratios (0.5, 1.0 and 1.5). Species mole fraction profiles were measured by an on-line gas chromatographic (GC). For comparison purposes, an experiment was also performed on RP-3, a conventional jet fuel commonly used in China, under the equivalence of 0.5. Compared to RP-3, ZH-HEFA exhibited significantly stronger low temperature reactivity and higher combustion conversion rates while demonstrating considerably lower yields of aromatics at high temperatures. The kinetic simulation of ZH-HEFA was achieved by proposing two surrogates and their corresponding kinetic models. Surrogate S-1 consisted solely of n-dodecane, while S-2 comprised 35% n-dodecane and 65% 2,6,10-trimethyl dodecane by weight. Both surrogate models were validated by the experimental data. S-1 exhibited a closer resemblance to the global oxidation characteristics of ZH-HEFA, whereas S-2 demonstrated improved accuracy in predicting the formation of small hydrocarbon intermediates during the fuel oxidation. Rate of production analysis revealed that the branched alkane component in S-2 possessed more pathways and greater capability than S-1 in generating C3 intermediates, which are important for the generation of aromatics. Furthermore, both models displayed good predictive performance for the auto-ignition properties of HEFA-SPK fuels.-

Biofuel production from palm oil deoxygenation using nickel-molybdenum on zirconia catalyst using glycerol as a hydrogen donor

The growing demand for renewable energy has generated interest in biofuels as alternatives to fossil fuels. Second-generation biofuels, derived from deoxygenating fats and oils, have garnered a higher level of interest from industry and academia due to their potential for direct replacement of diesel and jet fuels. Palm oil, mostly cultivated in Thailand and composed of C16 and C18 fatty acids, is a primary feedstock sought for biofuel production. Palm oil deoxygenation contains several pathways that may or may not require hydrogen gas. This study aimed to produce biofuels in different fuel ranges, such as gasoline, jet fuel, and diesel, through palm oil deoxygenation using glycerol as a hydrogen source. Glycerol, a low-value byproduct, was used as a hydrogen donor, whereas nickel-molybdenum-supported catalysts were chosen for their high efficiency in deoxygenation and cost-effectiveness. The study investigated the impact of reaction time, temperature, and catalyst activation method on palm oil deoxygenation. Catalyst characterization methods, including XRD, SEM, TEM, XPS, FTIR, TGA, and nitrogen-sorption, were employed to understand the role of catalysts’ activity during palm oil upgrading. Findings indicated that alkane hydrocarbons are the major components in liquid products. The presence of excess hydrogen in post reaction gaseous phase proves the hydrogen donation capability of glycerol. Increased reaction time and temperature facilitated the removal of oxygen from palm oil. Nickel-molybdenum on zirconia activated by sulfidation demonstrated higher stability than by reduction activation.

Aircraft performance of a novel SAF: Lower costs, lower environmental impact, and higher aircraft performance

Investing in Sustainable Aviation Fuel (SAF) is crucial for reducing the aviation industry’s carbon footprint and mitigating climate change. As global air travel demand increases, SAF offers a viable solution to significantly lower greenhouse gas emissions and enhance energy security, ensuring a more sustainable future for aviation. Additionally, converting biomass, particularly waste materials, into SAF adds value by turning potential environmental liabilities into valuable energy resources, promoting a circular economy and reducing overall waste. This study evaluates the aircraft performance of a novel sustainable aviation fuel (SAF) derived from multiple feedstocks in a hybrid biorefinery. SAF performance is compared to two conventional jet fuels, specifically a blend of 30% kerosene and 70% gasoline and JET-A1. The results demonstrated that the optimal SAF outperformed conventional fuels in terms of both thrust and range. Specifically, SAF exhibited a 17% increase in thrust and a 10% increase in range compared to conventional Jet A1 fuel. This novel fuel did not only mitigate CO2 emissions and achieve a cost reduction of 0.13 to 8.08%, but also exhibited superior aircraft performance. In addition, this fuel also meets the criteria of a “drop-in fuel” as it does not necessitate significant alterations to the currently existing CFM56-7B turbofan engine. This is due to its similar key thermodynamic indicators, such as heat capacities and combustion temperature, which are comparable to those of conventional jet fuels. In addition, this paper identifies the sensitivity of the CFM56–7B turbofan engine fuelled by the novel fuel.

Furanic jet fuels – Water-free aldol condensation of furfural and cyclopentanone

A method for the water-free, large-scale synthesis of bio-jet fuel precursors, distinct from traditional fossil-based sources, is introduced. This approach involves the aldol condensation of furfural with cyclopentanone, producing C10-C15 fuel precursors eligible for further hydrodeoxygenation to high-performance diesel and jet fuel hydrocarbons. In the context of process integration, aldol condensation reactions were conducted under water-free conditions, utilizing excess furfural as the solvent. Evaluation of various commercial catalysts confirmed the feasibility of running in excess furfural. Both basic and acidic catalysts demonstrated significant activity, with CaO and amorphous silica-alumina achieving ≥80 mol% conversion of cyclopentanone and yielding ≥80 mol% selectivity towards the desired fuel components within 5 h of reaction. However, an overlooked aspect is the notable formation of undesired heavy side products. Observations indicated that the high furfural concentration, combined with the use of strong acidic catalysts, were the primary cause of heavy side product formation. The strong base catalyst, CaO, significantly reduced the formation of these oligomers, but did not appear to stop it completely. Interestingly, water content did not appear to play a major role in byproduct selectivity. To further suppress the formation of oligomers, the use of process-owned intermediates as solvents is proposed.

Towards hydrogen gas turbine engines aviation: A review of production, infrastructure, storage, aircraft design and combustion technologies

This study explores the potential of hydrogen gas turbine engines for sustainable aviation, with a particular focus on their development for low subsonic to transonic flight regimes. Hydrogen offers notable advantages, including zero CO2 emissions and high energy density. However, its widespread adoption is prevented by significant challenges in production, infrastructure, storage, aircraft design, and combustion technology. The limited availability of green hydrogen – the global production totaled only 127 kt in 2023, with 76% produced in China - raises concerns about the feasibility of a rapid shift to hydrogen-powered general aviation. Despite numerous pledges for hydrogen adoption in the Western world, major aircraft manufacturers have primarily engaged in marketing activities rather than substantial product innovation. To date, the only hydrogen aircraft demonstrator from this century is the 2012 Boeing Phantom Eye, which utilized modified hydrogen internal combustion engines rather than a gas turbine engine. The only hydrogen aircraft demonstrator with a gas turbine engine was the 1988 hybrid Tupolev Tu-155 which coupled one hydrogen gas turbine engine to other two jet fuel engines. This paper evaluates the current state of hydrogen gas turbine technology, comparing its combustion characteristics with traditional jet fuels and examining various NOx emission control techniques. It also investigates the potential of micro-mix lean combustion and staged combustion to achieve efficient and low-emission hydrogen combustion in gas turbines. Given the more extensive experience with terrestrial gas turbines compared to their aeronautical counterparts, the review includes insights from terrestrial power generation applications. Additionally, it considers hythane - a blend of hydrogen and natural gas - as a transitional solution for significantly reducing CO2 emissions while progressing towards net-zero targets. The review underscores the urgent need for advancements in green hydrogen production, technology, and infrastructure to overcome existing barriers and enable a more sustainable aviation future powered by hydrogen. Importantly, the review emphasizes the need to move beyond mere virtue signaling and make tangible progress toward a hydrogen economy.

Integrating microwave pyrolysis and hydrotreating for converting low-density polyethylene into jet fuel

With the increasing plastic waste and its environmental impact, finding effective recycling solutions is essential. Cracking plastic waste followed by hydrogenation could be a promising method for producing jet fuels. In the present work, microwave-assisted pyrolysis (MAP) with MgO combined with hydrotreating with a Ni/Biochar catalyst was firstly proposed to convert low-density polyethylene (LDPE) into jet fuel. The pyrolysis process yielded 48.5 wt% of liquid product, with C5−C15 hydrocarbons and olefins accounting for 87.6% and 65.5%, respectively. During the hydrotreating process with 10% Ni/Biochar at 300°C of temperature and 2 MPa of initial H2 pressure, the pyrolysis oil was successfully hydrotreated, resulting in 98.4% paraffins and 1.6% aromatics with liquid yield of 80.6 wt%. Among them, C5−C15 hydrocarbons created 96.1%. The kinetic analysis indicated an activation energy of 89.9 kJ/mol for hydrogenated LDPE pyrolysis oil (HPPO). Characterization of the Ni/Biochar catalyst after reaction showed a BET surface area of 438 m2/g, similar to that of the fresh catalyst, with minimal coke formation noted via XRD, TEM, and TG analyses. XPS and FTIR indicated negligible oxidation of Ni0 during hydroprocessing. After 6 cycles, the catalyst remained high abundance for paraffins and C5−C15 hydrocarbons, namely, 98.4% and 94.0%, respectively, demonstrating its stability.

Comparative analysis of the combustion and emission characteristics of biojet and conventional Jet A‐1 fuel: a review

AbstractConventional jet fuels derived from fossil sources contribute to greenhouse gas emissions and air pollution, leading to climate change. Recent studies have shown that biobased jet fuels from different feedstocks offer a more sustainable alternative to conventional fuels as they are derived from renewable biomass, reducing greenhouse gas emissions. The major feedstocks reviewed are jatropha curcas, camelina, karanja oil, waste cooking oil, and municipal solid waste. They offer diverse benefits for sustainable aviation fuel development. As a comparative analysis, this review examined jet fuel characteristics based on their physicochemical properties, namely energy content, viscosity, calorific value, cetane number, and freezing and flash points. The objective was to understand the influence of the properties on performance evaluation, environmental impact, and combustion characteristics. The properties of biojet fuels are compared with their fossil counterparts to validate their suitability as renewable alternatives and their benefits in terms of emissions reduction and engine performance. Biojet fuels perform better in terms of lower sulfur content, lower soot content, and a lower freezing point, their aromatic content, and their high cetane number. This study enhances the understanding of biojet fuels and their quality, and supports the development of sustainable fuel options. Overall, adherence to the American Society for Testing and Materials (ASTM) D7566‐18 standard is crucial for the acceptance and integration of biojet fuels into the aviation sector. Future research should explore feedstocks such as wood biomass, wastepaper, and agricultural residues for biojet fuels. It should also investigate the combustion and emission characteristics of biosourced aviation fuel at higher blending ratios (>50% by volume) with fossil Jet A‐1.

Fuzzy Rule-based Comparison of Alternative Jet Fuels

In today's aviation alternative jet fuels play an increasingly important role. Their application incurs new engineering and environmental protection challenges. The key properties of their feasibility of integration are from technological point of view aging behavior and applicability as well as from environmental protection point of view the carbon footprint. During the comparison process experts can evaluate the above characteristics with linguistic variables. The application of linguistic variables always results in some degree of uncertainty – by their subjectivities. Fuzzy calculation methods are used to mathematically describe these uncertainties. The purpose of this study as a pilot project is to gain experience in developing a methodology of a multi-level fuzzy rule-based jet fuel qualification process.