Mixed Fuels Research Articles

Evaluation of Fuel and Air Mixing in a Scramjet Engine Using an Asymmetric Strut-Based Fuel Injection Using CFD

ABSTRACT In this paper, a new asymmetric strut-based fuel injection is proposed and investigated for enhanced fuel-air mixing and combustion in supersonic combustors. The strut configuration is re-designed from a general symmetric strut to asymmetric strut such that asymmetry in the strut creates the vortices along the Z-axis (longitudinal) after the flow crosses over the lip of the strut. In the downstream of the combustor, the flow circulation grows resulting in improved mixing of fuel and air. The fuel is injected from the strut about the centerline of the combustor. Due to the presence of vortices inside the combustor, the air and fuel mixes properly which significantly increases the mixing and combustion efficiency. Various performance parameters are compared with a symmetric strut case to present a quantitative comparison between two injection schemes to show the advantages of enhanced mixing due to the application of asymmetric struts in supersonic combustors.

Evaluation of a potential reintroduction of nuclear energy in Italy to accelerate the energy transition

Nuclear energy was adopted in Italy in the past to deal with the insufficient fossil fuels on the national territory. After a public vote subsequent to the Chernobyl accident, Italy abandoned the use of nuclear energy and nowadays adopts a mix of fossil fuels and renewable energy sources for electricity production. However, the urging environmental pollution and climate change issues are forcing Italy to realize a so-called “energy transition” towards a more sustainable energy production and consumption system. In this framework, following the examples of other countries, it could be re-evaluated the adoption of nuclear to reduce the consumption of fossil fuels. In the present paper, it is presented an overview of the nuclear energy history in Italy and the current and projected electricity demand and supply. Then, with reference to the Italian framework and policies, the main advantages and disadvantages of a hypothetical reintroduction of nuclear energy are presented. The analysis shows that the adoption of nuclear energy would bring several advantages in terms of lower emissions, higher security of supply and enabling of possible other technologies; the main disadvantages are related to the opposing public opinion and the nuclear waste management.

Moisture content thresholds for ignition and rate of fire spread for various dead fuels in northeast forest ecosystems of China

Fuel moisture content is one of the important factors that determine ignition probability and fire behaviour in forest ecosystems. In this study, ignition and fire spread moisture content thresholds of 40 dead fuel were performed in laboratory experiments, with a focus on the source of ignition and wind speed. Variability in fuel moisture content at time of ignition and during fire spread was observed for different fuels. Matches were more efficient to result in ignition and spread fire with high values of fuel moisture content compared to the use of cigarette butts. Some fuels did not ignite at 15% moisture content, whereas others ignited at 40% moisture content and fire spread at 38% moisture content in the case of matches, or ignited at 27% moisture content and spread fire at 25% moisture content using cigarette butts. A two-way ANOVA showed that both the source of ignition and the wind speed affected ignition and fire spread threshold significantly, but there was no interaction between these factors. The relationship between ignition and fire spread was strong, with R2 = 98% for cigarette butts, and 92% for matches. Further information is needed, especially on the density of fuels, fuel proportion (case of mixed fuels), fuel age, and fuel combustibility.

The Influence of Water and DEE as Additives with Diesel Fuel in a Light Duty Diesel Engine Generator-An Experimental Investigation

Currently, our global environment has been affected due to the air pollution caused by many sectors (such as automotive, industrial, transportation) in higher magnitudes. Many environmentalists, scientists, researchers and engineers have contributed their efforts to eradicate the air pollution. It is well known noted that most of the harmful pollutants were evolved from diesel engine power engines/plants. Considering the objective of enhancing performance and reducing harmful emissions of diesel engine, the current research work has been conducted on mixing DEE (Di-Ethyl Ether) and normal water with normal diesel fuel in definite quantities. Five stages of investigations were carried out to perform the task of blending water and DEE with the normal diesel fuel. In the first stage, to obtain the baseline readings, normal diesel fuel was experimented in a light duty constant speed diesel engine. Normal water (2% & 4% by vol.) was combined with the normal diesel fuel with the aid of emulsifiers (Span80 & Tween80) and mechanical stirrer (speed of 3000 rpm) to obtain the water blended diesel emulsion fuels in the second stage. In the third stage, DEE was mixed with water-emulsion fuels which were prepared in the second stage. The stability and properties of fuels was determined in the fourth stage. In the fifth stage, the prepared stable DEE-water-diesel emulsion fuels were tested in a light duty constant speed diesel engine generator and eventually compared to those readings of normal diesel fuel. Experimental outcome from all the tested fuels revealed that water and DEE mixed emulsion fuels reflected better performance and reduced harmful emission attributes.

Analysis of Mo-99 production as function of CAMOLYP reactor power

CAMOLYP or critical assembly for molly production is a nuclear reactor based on mixed uranium thorium fuels, which is currently being developed in BATAN Yogyakarta. This study aims to know how much the amount of 99Mo isotope production can be achieved on 6 days reactor operation as function of different power levels. The method is a calculation of reactor physics simulation by using MCNPX computer code. The calculation is done for the reactor core configuration of 23 thorium dioxide fuel rods in the outer ring with the total mass of 73.12 kg and 1.706 kg of 235U in the annulus. The analysis result shows that the CAMOLYP’s 99Mo production can be formulated as linear function of the reactor power level in watt. From the analysis result, it can be concluded that the CAMOLYP reactor can produce 39.91 curie 99Mo at 1000 watts and 6 days operations. This analysis result indicates that the CAMOLYP reactor as a low power reactor has succeeded in producing 99Mo isotope which is sufficient for domestic needs.

THE EFFECT OF FUEL MIX, MODERATED BY INDONESIA CRUDE PRICE AND FOREIGN EXCHANGE, AND POWER LOSSES ON PROFITABILITY OF PT PLN (PERSERO)

Like any other corporate, state owned enterprises (SOE) main objective is to achieve optimum profit to ensure its sustainability. In Indonesia, electricity business in run by PT PLN (Persero), a corporate owned 100% by Government of Indonesia. Thus, PLN should maximize its effort on cost reduction and sales volume optimization to ensure its profitability growth. Looking at the structure of operational cost and revenue, this study aims to explore the effect of fuel mix and power losses on profitability (operating profit/loss) of PLN, where the moderating role of Indonesia crude price (ICP) and exchange rate on fuel mix effect toward profitability also take into account. By using moderated regression analysis (MRA), this study found out that the effect of fuel mix on profitability, and power losses on PLN’s profitability exist negatively. ICP and exchange rate also strengthen the effect of fuel mix on PLN’s profitability. This study suggested PLN to continue exploring ways to optimize its fuel mix and power losses, as well as increasing sales volume. This could not be done without Government intervention that favors PLN i.e., tariff adjustment or incentives, especially when exchange rate and ICP value worsen. This is to ensure that PLN has a healthy financial sustainability. Keywords: PT PLN (Persero), Electricity Tariff, Fuel Mix, Indonesia Crude Price , Exchange Rate, Power Losses, Profitability JEL Classifications: E3, L11, M11, R32, G39 DOI: https://doi.org/10.32479/ijeep.9575

Ignition of Hydrogen–Hydrocarbon (C1–C6)–Air Mixtures over the Palladium Surface at 1–2 Atm

In this paper, we report the results of studying the combustion characteristics of fuels containing a hydrogen–hydrocarbon (C1–C6, as in CH4, C2H6, C3H8, C4H10, C5H12, and C6H14) mixture with a fuel fraction of 0.6–1.2 in a mixture with air above the palladium surface at a total pressure of 1–2 atm. The propagation features of the flame front in mixed fuels are revealed, and the temperature dependences of the ignition limit over the palladium surface are determined. The observed separation of the CH and Na emission bands in time during the combustion of the 30% propane + 70% H2 + air mixture (the fuel fraction in the mixture with air is unity) was established to be caused by the occurrence of hydrodynamic instability of the flame when it touches the end of a cylindrical reactor.

Model for calculating the characteristics of fuel injection and atomization in diesel when working on alcohol-fuel emulsions

The solution to the problem of air pollution can be the transfer to alternative mixed fuels based on alcohol with the specified physical and chemical characteristics of power engines installed on vehicles and running on oil fuel, which will significantly expand the raw material base for obtaining motor fuels. The mechanisms of crushing a drop burning in an open atmosphere are considered, taking into account the repeated crushing of an emulsion drop as a result of boiling of intra-phase water inclusions and the model of evaporation of the drop in the absence of intensive internal circulation, when the rate of fractional evaporation of each component is determined by its mass fraction.

Investigation on the characteristics of pyrolysates during co-pyrolysis of Zhundong coal and Changji oil shale and its kinetics

Xinjiang province, China, contains abundant Manasi coal and Changji oil shale resources. While, Manasi coal is rich in AAEMs and Changji oil shale has low oil yield. Therefore, the co-pyrolysis technique of Manasi coal and CJR oil shale is adopted to achieve the purpose of increasing the pyrolysis oil and gas yields. The results revealed that oil and gas yields were improved during co-pyrolysis, and when the proportion of Manasi coal was 5%, the oil and gas yields were increased by 8.20% and 2.65%, respectively. The concentrations of H2 and CH4 in the co-pyrolysis gas were higher than the weighted values. And, the relative content of short-chain aliphatic hydrocarbons increased in the pyrolysis oil of mixed fuels, leading to the conversion from heavy oil to light oil. The prediction model of oil yield during co-pyrolysis was proposed. When the proportion of Manasi coal was 10%, the synergistic index of co-pyrolysis was the highest. In addition, the synergy during co-pyrolysis occurred when the temperature exceeded 455 °C, which originated from the catalytic effect of AAEMs. When the conversion rate exceeded 0.5, the E values of MF1 and MF2 were lower than individual fuels during pyrolysis, and synergistic and catalytic effect occurred.

Research of the influence of alternative fuels on diesel engine noise level

One of the advantages of using alternative fuels in internal combustion engines is the possibility of reducing noise. The article presents the methodology and some results of the research of structure-borne noise of internal combustion engines related to the working process. The main characteristics of alternative fuels allowing reduction of the noise level by modifying parameters of the heat release law and reducing the pressure growth rate are analyzed. The results of calculated and experimental research of the diesel engine structure-borne noise during its operation on gas and mixed fuels are presented. The research showed that the greatest effect is achieved when converting diesel engine to spark ignition gas engine. For gas-diesel engines, noise reduction of the working process is much lower because a high compression ratio is preserved. The use of mixed fuel revealed a need to correct the injection advance angle to reduce the noise level.

Berkut Code Validation on Post-Reactor Studies of Irradiated Bn-600 Fuel Rods with Mixed Uranium-Plutonium Nitride Fuel

An advanced version of the BERKUT-U/V2.1 code intended for modeling the behavior of fuel rods with oxide or nitride fuel in standard and emergency operating regimes of fast reactors with liquid-metal coolant is being developed at the Nuclear Safety Institute, Russian Academy of Sciences (IBRAE RAS), as part of the project Next-Generation Codes of Project Proryv (Breakthrough). The present work reports the results of the validation of an advanced version of the code based on post-reactor studies of BN-600 fuel rods (KETVS-1, -6) and BREST-OD-300 fuel rods (ETVS-5) with mixed uranium-plutonium nitride fuel, irradiated in the BN-600 reactor.

Synthesis of yellow persistent phosphor garnet by mixed fuel solution combustion synthesis and its characteristic

Persistent phosphor Gd3Al2Ga3O12:Ce3+-Cr3+ (GAGG:Ce3+-Cr3+) has been synthesized by solution combustion synthesis (SCS) incorporating mixed organic fuels of glycine and urea at 773 K. Using only single fuel can lead to incomplete combustion and amorphous products. Without additional heat treatment, a porous and pulverized GAGG:Ce3+-Cr3+ powders can be obtained when the fuel ratio ϕ = 1. The products exhibited yellow color emission in visible light photoluminescence. This emission is originated from Ce3+. Photoluminescence excitation spectra indicated that GAGG:Ce3+-Cr3+ can be well excited by blue light, marking its potential for white LED lights application. In comparison with green luminescence Y3Al2Ga3O12 doped with Ce3+-Cr3+ (YAGG:Ce3+-Cr3+), the yellow color in GAGG:Ce3+-Cr3+ is due to crystal field splitting when Y is substituted by Gd. Also, electron energy-loss spectroscopy measurement using scanning electron microscopy (STEM-EELS) showed that the band gap decreased in 6.14 eV, 6.05 eV and 5.93 eV order when Ga content (x = 2.5, 3, 3.5) increased. The bandgap change showed that the trap level produced by Cr3+ ions affected the persistent luminescence. In this study, when Ga content x = 3, Gd3Al5-xGaxO12:Ce3+-Cr3+ exhibited the longest persistent luminescence.

Evaluation of combustion properties and pollutant emission characteristics of blends of sewage sludge and biomass

The combustion and emission characteristics of sludge, biomass (rice husk, peanut husk, pine sawdust) and their blends were studied by non-isothermal thermogravimetry, tube oven method and SEM. The results showed that the combustion process of sludge, biomass and their blends could be divided into three stages: the evaporation of water, the release and combustion of volatile, combustion of char. Combustion characteristics of 80% biomass +20% sludge were improved compared with the theoretical value. NOx and SO2 emission of 80% biomass +20% sludge was lower than that of sludge combustion. There was synergistic effect between sludge/biomass combustion. Comparing combustion and emission characteristics comprehensively, the mixed fuels of 80% biomass +20% sludge could promote combustion and reduce emissions, which was a better method to treat municipal sludge.

CO2-to-Fuels Renewable Gasoline and Jet Fuel Can Soon Be Price Competitive with Fossil Fuels

Download : Download high-res image (69KB) Download : Download full-size image Rob McGinnis, PhD, is an inventor and entrepreneur. He is the founder and CEO of Prometheus, a company that is developing technology to remove carbon dioxide from the air and turn it into fuels. He previously founded Mattershift, where he developed large-scale carbon nanotube membranes. Rob was previously founder of Oasys Water, a company focused on developing forward osmosis technologies for water purification. Rob received his PhD in Engineering from Yale University.

Effect of injection position on fuel spray and mixture preparation of a free-piston linear engine generator

Fuel spray and mixing in linear engines is coupled by dynamics, combustion, and gas exchange, which differs from that in conventional engines. This work presents a system simulation to reveal the multi-process coupling effect of injection position on the fuel spray and mixing of a free piston linear diesel engine (FPLE). A full-cycle fuel spray model which couples with dynamic, combustion, and gas exchange is established to predict the coupled effect on mixture formation. The results indicate that the variable injection position changes the FPLE motion through multi-process coupling effect, resulting in different boundary conditions for fuel spray and mixing. Relatively large injection advance position leads to more residual gas, fast speed, intense turbulence, low gas pressure, and temperature at the moment of injection for mixture formation. The earlier fuel injection generally makes the longer spray penetration, smaller Sauter mean diameter of droplets, less fuel impingement, faster fuel evaporation rate, and more evaporated fuel mass. However, too early injection does not support the above results. Suggesting that in order to achieve homogeneous combustion mode, the large injection advance position injection schedule operation is a good choice for the FPLE due to its long ignition delay duration for fuel atomization, evaporation, and mixing.

An extensive study on skeletal mechanism reduction for the oxidation of C0–C4 fuels

The AramcoMech 3.0 mechanism containing 581 species and 3037 reactions for oxidation of hydrocarbon and oxygenated C0C4 fuels is reduced using six direct relation graph (DRG) related methods for the following fourteen fuels: hydrogen, carbon monoxide, methane, formaldehyde, methanol, acetylene, ethylene, ethane, acetaldehyde, ethanol, propene, 1,3-butadiene, isobutene and 2-butene. Maximum error on ignition delay times increases sharply when certain species is removed from skeletal mechanisms in skeletal reduction and it is difficult to achieve compact skeletal mechanisms for some fuels. This indicates that some important species are identified as redundant species with these methods. A fixed species scheme (FS) is proposed in skeletal reduction, where these species are regarded as important species and are retained in the skeletal mechanism. Smaller skeletal mechanisms can be achieved with this FS method given a certain maximum error. Skeletal mechanisms for each of the fourteen fuels with a maximum ignition delay time error of less than 10% are obtained. A comprehensive skeletal mechanism including 149 species and 925 reactions with a maximum error of 15% on ignition delay times is further achieved using the sensitivity analysis method starting from the union of the skeletal mechanisms for the fourteen fuels. The 149-species comprehensive skeletal mechanism and fourteen skeletal mechanisms are shown to provide reasonably key combustion characteristics for single-component fuels, including the laminar flame speeds, ignition delay times, and major species mole fraction profiles under a wide range of pressures, temperatures and equivalence ratios compared with experimental data and those of the detailed mechanism. Moreover, the 149-species skeletal mechanism can reproduce the combustion properties of some multi-component mixed fuels. The comprehensive skeletal mechanism can be employed as a core reaction base for developing mechanisms of other large hydrocarbon and oxygenated fuels.

Structural and optical properties of ZnAl2O4 powders synthesized by solution combustion method: Effects of mixture of fuels

Solution combustion method was used for synthesis of ZnAl2O4 powders by zinc nitrate and aluminum nitrate as oxidant using various amounts of glycine-urea mixed fuels. The combustion behavior was evaluated in open and closed systems. Thermal analysis, X-ray diffractometry, electron microscopy, and diffuse reflectance and photoluminescence spectroscopy techniques were used for evaluating phase evolution and characterization of microstructure, and optical properties. Single phase ZnAl2O4 powders were prepared using higher amounts of fuel following calcination at 700 °C. The powders synthesized in a closed system showed larger band gap energy (3.90 eV) in comparison with open system (3.52 eV). The blue emission was disappeared in the closely combusted ZnAl2O4 powders due to their normal spinel structure.

Conditions and characteristics of mixed fuel granules ignition based on coal and finely dispersed wood

Analysis of the possibility of lumber waste disposal via combustion in a mixture with coal has been conducted. Conditions and characteristics of pellets ignition of fuel mixtures based on coal dust and grounded wood at various mass concentrations of the components have been experimentally determined. Fuel pellets were made by cold pressing on a hydraulic press. The experiments were performed in a medium of still air heated to high (from 600 °C to 800 °C) temperatures. Record of heating processes of the researched promising for thermal power engineering granules of mixed fuels, their subsequent ignition and combustion has been conducted using a high-speed video camera (image format - 1024 × 1024 pixels, frame rate - up to 100000 per second), which provides high discretization of registration results of processes characteristic times. It has been established that an increase in the proportion of wood components in the fuel granule significantly reduces values of ignition delay times of all researched mixtures based on 2B and 3B brown coal. The limit of stable ignition of such fuels has been determined. It is shown that ignition delay times of fuel pellets with characteristic sizes up to 8 mm (height) with diameter of 8 mm even at relatively low temperatures of the combustion medium do not exceed 16 s, which illustrates the promising application of such fuels even in small-scale power engineering.

The study of the performance of a diesel nozzle on mixed fuels with insufficient low-temperature properties

Today, the properties of rapeseed oil, affecting the fuel supply processes in a tractor diesel, are density, kinematic and dynamic viscosity, as well as surface tension. The purpose of this research is to expand the limits of the fuel base of tractor diesel engines by using mixed fuels with insufficient low-temperature properties. In this regard, the determination of the optimal composition of mixed fuel for the operation of the fuel supply equipment of tractor diesels is a very urgent task. To solve this problem, theoretical studies were conducted to determine the effect of rapeseed oil additives on the properties of mixed fuels, as well as testing a diesel fuel injector. As a result of the studies, the dependences of the viscosity of the mixed fuel, the pressure of injection beginning, the tightness of the locking cone, and the hydro-density of the spray nozzle on the addition of rapeseed oil with an additive were determined. Based on theoretical calculations, the value of the viscosity of mixed fuel that meets the requirements of the manufacturer's specifications for fuel injectors is obtained. An analysis of the experimental dependences showed that with an increase in the proportion of rapeseed oil in mixed fuel from 0 to 100 %, there increased: the pressure at the beginning of injection from 20,88 to 21,08 MPa, the time until a drop of fuel comes off from the nozzle of the spray from 18 to 104 s, and pressure reduction time decreased from 5,2 to 11,3 s. Tests shown that for all mixed fuel compositions, the injection start pressure, tightness on the locking cone, spray water density and spray needle mobility meet the requirements of GOST 10579-2017, however, the spray quality corresponds to mixed fuel compositions with rapeseed oil up to 60 %. Thus, the use of the proposed fuel compositions will improve the low-temperature properties of mixed fuels with additives of rapeseed oil, and thus expand the fuel base of tractor diesels.

Serious game for modelling neighbourhood energy supply scenarios

Scientific evidence suggests that in developing neighbourhoods, which are under-serviced by centralised energy distribution grids, the reasonable solution is a mix of grid and off-grid energy provision, as well as a mix of fossil fuels and renewable energy sources. The assumption shapes a theoretical foundation for a serious game, Energy Game, which emerged as a result of an international interdisciplinary student collaboration. The aim of the Game, on the one hand, is the simulation of user behaviour choosing between various energy options based on their cost efficiency, and on the other hand, the education of design and engineering students, as well as other interested parties, about neighbourhood energy production and delivery. The outcome of the Game represents a distribution of various energy options across the neighbourhood, and may potentially inform planning decisions about neighbourhood energy provision. The results of game sessions with students indicate the viability of the Game for education, energy demand and supply modelling, as well as highlighted the requirements for enhancing the playfulness of the Game and, apart from costs, the need to include the environmental impact of energy provision options into game mechanics.