Fuel Communications最新文献

Chemical activation was employed to convert algal biochar obtained from hydrothermal carbonization of lipid-extracted algae (LEA) to activated carbon. Potassium hydroxide, previously utilized on cellulosic biomass but not on algal biomass, was employed as activating agent and the impact of the activation conditions, namely temperature, activation time, and amount of activating agent, were investigated. The yield of activated carbon from biochar ranged from 28 % to 52% and decreased as the temperature was raised from 400 to 600 °C, the residence time from 30 to 60 min, and the KOH/biochar mass ratio from 0.25 to 1.0. In contrast, surface area increased by 2.1-fold when the activation temperature was raised to 600 °C and by 1.5-fold when the KOH: biochar ratio was raised to 1.0. Maximum BET surface area of 847 m²/g was achieved at 600 °C after 30 min at a mass ratio of 1:1. The integrated hydrothermal carbonization and activation process of LEA was simulated in Aspen Plus® and the technoeconomic feasibility was assessed based on our experimental data at 1,000 and 10,000 acres of cultivation area. For the latter, net present value analysis determined a minimum selling price of $2,200/ton for algal activated carbon with a financial breakeven achieved in 3.5 years. This is cost-competitive with the current price of commercial fossil-derived activated carbon, which is $1,543-$2,645/ton. Sensitivity analysis showed that the minimum selling price is significantly affected by algal biomass yield during cultivation and is more sensitive to the operating expenses than to the capital investment.

Nanoparticles are being used as additives for solid and liquid fuels owing to their high specific surface area (high reactivity) and potential ability to store energy in surfaces. The use of nanoparticles in diesels, biodiesels, and their blends is a novel area with unrealised potential owing to the higher catalytic activity of nanoparticles compared with that of micro-sized materials Nanoparticles have been shown to disperse more evenly in fuels and exhibit high stability. In addition, nanoparticles in similar media burn faster than micro-sized particles. The addition of nanoparticles into diesel, biodiesels, and their blends affect the physicochemical properties of the fuels such as kinematic viscosity, density, flash point, and cetane number. Studies have shown that nanoparticles affect the brake specific fuel consumption, brake specific energy consumption, and brake thermal efficiency, depending on the dosage and type of nanoparticles. Studies have also shown that the addition of nanoparticles affect carbon monoxide, carbon dioxide, nitrogen oxide, and unburned hydrocarbon emissions, along with smoke opacity. This review presents the application of various types of nanoparticles in diesel, biodiesels, and their blends to enhance the physicochemical properties of the fuels, combustion efficiency, and engine performance, and reduce harmful exhaust emissions. It is believed that this review will be beneficial to scholars, researchers, and industrial practitioners looking forward to improve diesel engine performance and reduce exhaust emissions by exploiting nanotechnology.

Cogongrass (Imperata cylindrica) can be processed into a positive electrode as a battery component to generate electricity by utilizing its carbon element. This study used various activators, KOH and H₃PO_4, and characterized using XRD, FTIR, and SEM-EDX and electrical tests with electric conductivity analysis. The analysis results using XRD diffraction showed that when using both KOH and H₃PO₄ activators, Cogongrass carbon has graphite (C) and silicon (Si) crystals but at different peaks. The carbon has the same functional groups for both activators: OH-bending, C=C-bending, C-O-bending, and C=C-bending. Cogongrass carbon with KOH activator has a pore size of 235-980 nm with a percentage of carbon atoms of 71.29%, while with H₃PO₄ activator has a pore size of 110-960 nm with a higher percentage of carbon atoms of 75.04%. The elements contained in carbon are the same for both activators, namely carbon, oxygen, silicon, indium, potassium, calcium, iron, chlorine, phosphorus, magnesium, and sodium. EC analysis showed that carbon from Cogongrasss showed electric conductivity reaching 140 µs/cm at 60 minutes pyrolysis time.

The addition of hydrogen in ammonia/air mixtures can lead to the onset of intrinsic flame instabilities at conditions of technical relevance. The length and time scales of intrinsic instabilities can be estimated by means of linear stability analysis of planar premixed flames by evaluating the dispersion relation. In this work, we perform such linear stability analysis for hydrogen-enriched ammonia/air flames (50%H2-50%NH3 by volume) using direct numerical simulation with a detailed chemical kinetic mechanism. The impact of pressure and the inclusion of the Soret effect in the governing equations is assessed by comparing the resulting dispersion relation at atmospheric pressure and 10 atm. Our data indicate that both pressure and the Soret effects promote the onset of intrinsic instabilities. Comparisons with available numerical literature data as well as theoretical models are also discussed.

Unique fatty acid methyl esters (FAME) containing β‑hydroxy esters were produced using an engineered microorganism by glucose fermentation. This study investigated the properties of the unique FAME mixture both neat and in blends with conventional diesel, as well as properties of β‑hydroxy esters. The unique FAME blend contained relatively shorter-chain FAME (average fatty acid chain carbon number 14.6) with 58 % monounsaturated fatty acids and 9 % saturated and monounsaturated β‑hydroxy acid chains. The unique FAME had significantly lower distillation T90 (321 °C versus 352 °C) and higher cetane number (56.7 versus 52) compared to soy biodiesel. Cloud points were within method repeatability. Unexpectedly (because of the lack of methylene-interrupted double bonds), the unique FAME had low oxidation stability (1.5 h) as determined by Rancimat induction period. Stability could be improved through addition of commonly used antioxidants. We speculate that monounsaturated β‑hydroxy FAME may be the source of this instability. Blends with conventional diesel up to 50 vol% showed similar kinematic viscosity (within method repeatability) as blends of conventional FAME. The unique FAME had no effect on distillation T90 even at the 80 % blend level. A 30 vol% blend into conventional diesel had a Rancimat induction period of only 2 h, very nearly the same as the neat unique FAME sample. The addition of antioxidants produced blends of acceptable stability. Based on an assessment of the properties of individual β‑hydroxy FAME molecules, they have higher boiling point, higher cloud point, lower cetane number, and potentially lower storage stability than analogous FAME not having the β‑hydroxy group. Removing them from the fuel product in the production process may result in a biodiesel product with superior properties to what is on the market today.

A multi-agency effort is underway to decarbonize the aviation industry by 2050 and replace current fossil fuels such as Jet A. Carbon-free hydrogen-based technologies are a long-term opportunity for some markets, but the introduction of new sustainable aviation fuels (SAF) is necessary for a fleet-wide transition. These biofuels are synthesized to meet specific aviation fuel requirements; thus, they may be used in current jet engines without major modifications (i.e., drop-in SAF), accelerating the transition to net-zero carbon emissions by focusing on the life cycle of the biofuel (i.e., circular economy). Given the increased costs associated with the SAF certification process, a deeper understanding of the biofuel behavior at relevant operating conditions, ranging from take-off to high-altitude relight, becomes necessary to define the best candidates. This work investigates the performance of a real-fluid model (RFM), built upon cubic equations of state, in predicting the relevant fuel properties that dictate the atomization, evaporation, and combustion processes. The simpler composition spectrum of SAFs compared to current fuels justifies the development of this modeling approach targeting its application to computational fluid dynamics (CFD) solvers as a more detailed alternative to typical surrogate mixing rules and tabulated properties. The study showcases the capabilities of the RFM using National Jet Fuels Combustion Program's (NJFCP) Category C fuels and offers guidelines toward the development of reliable and robust fluid-dynamics models to support the adoption of SAF in a broad range of conditions, including transcritical regimes. Here, the behavior of the mixtures challenges the validity of ideal fluid models and, therefore, the proposed formulation allows for a realistic fuel characterization at high-pressure and high-temperature conditions, and to explore beyond the currently available experimental datasets.

This study delves into the combustion characteristics of diesel-vegetable oil blends using an industrial fuel burner, shedding light on essential factors that impact the viability of these alternative fuels in industrial applications. Viscosity, a key concern in vegetable oil-based fuels, can be effectively mitigated by blending with diesel. This viscosity reduction enhances fuel atomization, optimizing combustion efficiency and mitigating nozzle blockages. The study also explores the density variation in these blends, indicating potential implications for combustion kinetics and injection dynamics. Furthermore, the research addresses the trade-off between energy content and viscosity reduction as the calorific value decreases with an increasing volume ratio of vegetable oil. Flame behavior, crucial for combustion system design, exhibits an inverse relationship with the volume ratio of vegetable oil, resulting in shorter and less intense flames at higher vegetable oil content. Through comprehensive experiments, the study demonstrates that increased vegetable oil content leads to reduced flame length and stability, primarily attributed to the elevated density and viscosity of vegetable oil. A comparative analysis highlights the similarity in combustion properties between a 40 % vegetable oil and a 60 % diesel blend, which exhibited a kinematic viscosity of approximately 1.58 cP emphasizing the potential of vegetable oil as a viable substitute for diesel in industrial fuel burners.

The significant rise in plastic consumption and waste generation, coupled with the urgent need for sustainable energy solutions, has led to innovative research seeking to convert plastic waste into valuable resources. This review focuses on the application of hydrothermal carbonization as a promising technique for transforming plastic waste into valuable products. It highlights the suitability of hydrothermal carbonization for plastic waste conversion, and presents recent reports showing promising results, prospects, and a range of potential hydrochar applications, including solid recovered fuels, catalysts, direct carbon fuel cells and supercapacitors. This review further presents the challenges in utilizing plastic hydrochar across different applications, which include feedstock variability, contamination, scalability, material properties, and environmental considerations. The need for optimized synthesis methods, stable performance, and long-term sustainability is also emphasized. The critical evaluation of the applications of hydrothermal carbonization can contribute to advancing sustainable waste management and renewable energy production.

This paper reports an investigation on the long-term storage stability of high percentage and reformulated biodiesel-diesel blends for the success of renewable energy initiatives. This study mainly focuses on the Indonesian context, where the mandated B30 biodiesel faces stability and hygroscopicity challenges. A novel approach incorporated hydrotreated vegetable oil (HVO) to mitigate instability while increasing the biodiesel percentage and was analyzed during storage stability over six months in highland and coastal areas. A comprehensive analysis evaluates physicochemical properties, including water content, kinematic viscosity, total acid number, oxidation stability, and microbial growth. Based on the results, biodiesel-diesel blends (B30, B40, and B30D10) revealed robust stability and quality under highland and coastal conditions. Acid numbers exhibited a slight upward trend during storage but stayed within specified limits, emphasizing limited oxidative changes. Oxidation stability surpassed standard limits for blends, highlighting the blends' resistance to oxidation, even in higher concentrations. Water content increased over time, reflecting biodiesel's hygroscopic nature, but all blends met diesel fuel standards after 6 months. Furthermore, the investigation provided valuable insights into biodiesel-diesel blends' stability, quality, and potential enhancements, contributing to informed decision-making in fuel formulation and quality control.

This work investigates the performance of a community microgrid (C-$\mu$Grid) in an islanded mode of operation. A control structure has been developed, which focuses on transient stability of the primary controllers (PCs) of individual distributed energy resources (DERs) in the community, and also when the DERs work in tandem to balance load and generation. This approach shows a method for decoupling the state vectors of a highly coupled system, so that the system parameters can be regulated separately with accuracy, speed and stability. This work also demonstrates a technique for analysing and minimizing the impact of communication delays, which may exist between two controllers at different hierarchies. Besides, our analysis shows that power transferred between the multiple buses of a C-$\mu$Grid causes voltage variation that is different from traditional power distribution. Accordingly, a power transfer method has been proposed. These aforementioned control designs have been modeled for a C-$\mu$Grid structure that forms part of a modified IEEE 13 bus system, and simulated in real-time using OPAL-RT. A comparative analysis has been performed between DER voltage references provided by traditional optimal power flow (OPF) and our proposed method of power transfer. The simulation results show stable system operation during normal condition, and post delay recovery, when our developed control and power transfer methods are used. However, certain combinations of voltage references provided by OPF destabilizes the PCs and degrades the quality of power injection into the grid. These results have been utilized to characterize the functional requirements of a C-$\mu$Grid Central/Distributed Controller.