Fuel Air Research Articles

The end of business-as-usual? – A critical review of the air transport industry's climate strategy for 2050 from the perspectives of Degrowth

In discourses around sustainability, increasing eco-efficiency through technological developments are highly popular as they promise the continuation of business-as-usual and appeal to economic actors whose primary motivation is to follow the paths of economic growth. Dominant narratives and visions about the bioeconomy also fit into this line of thinking by giving a central role to technological problem solving and decoupling, the opportunities of sustaining economic growth and advancing the extended use of renewable resources. In 2020, major actors of the air transport industry under the frame of the Air Transport Action Group issued Waypoint 2050 a global, sector wide strategy to tackle climate change and halve CO 2 emissions by the middle of this century. As we will establish in this paper, their sustainability strategies strongly rely on bioeconomic solutions such as sustainable air fuels and renewable energy, while their need to grow remains unquestioned. However, achieving sustainability is a wicked problem that needs clumsy solutions. And clumsy solutions only come about when highly different viewpoints are put on the table. Degrowth perspectives can most certainly enrich dialogues on sustainability transitions such as the current challenges the air transport industry faces. This paper aims to provide a critical review of Waypoint 2050, underlining why it is important for economists and policymakers to shift their understanding from pursuing endless growth toward Degrowth perspectives. We use the main arguments of Degrowth to interpret and analyse the air transport industry's climate strategy and reframe the discussions around sustainable aviation. Our goal is to show that Degrowth approaches can contribute to positively influencing the discourses of air transport by assessing the consequences of the sector and its reform strategy through diverse lenses. The discourse reflected in this paper would also be appropriate when applied to other top carbon producing industries and our assessment of air transport is not a directed criticism but rather an example on why business-as-usual scenarios need to be revisited.

Numerical Study of Radiation and Fuel–Air Unmixedness on the Performance of a Dry Low NOx Combustor

Abstract The development of gas turbine combustors is expected to consider the effects of radiation heat transfer in modeling. However, this is not always the case in many studies that neglect this for adiabatic conditions. The effect of radiation is substantiated here, concerning the impact on the performance, mainly the emissions. Also, the fuel–air unmixedness (mixing quality) influenced by the combustor design and operational settings has been investigated with regard to the emissions. The work was conducted with a Mitsubishi-type dry low NOx combustor developed and validated against experimental data. This 3D computational fluid dynamics study was implemented using Reynolds-averaged Navier Stokes simulation and the radiative transfer equation model. It shows that NO, CO, and combustor outlet temperature reduce when the radiative effect is considered. The reductions are 17.6% and below 1% for the others, respectively. Thus, indicating a significant effect on NO. For unmixedness across the combustor in a non-reacting simulation, the mixing quality shows a direct relationship with the turbulence kinetic energy (TKE) in the reacting case. The most significant improvements in unmixedness are shown around the main burner. Also, the baseload shows better mixing, higher TKE, and lower emissions (particularly NO) at the combustor outlet, compared to part-load.

Non-Premixed Liquid Fuel Air Flame in a Miniature Combustor with Modified Flow Aerodynamics

ABSTRACT This study determines the effect of flow aerodynamics modification on the combustion characteristics of a new miniature combustor. The n-heptane was injected into the combustor at a flow rate of 1.0 ml/min to 2.5 ml/min, and the airflow rate varied between 7.0 l/min and 20.0 l/min at a successive fuel flow rate to maintain the equivalence ratio. The flame was confined in the combustor in the lean fuel regime. The modified combustor stabilized and sustained the flame at a high Reynolds number. This study used a numerical simulation of the isothermal flow to explain the results of the experiment. The recirculation zone at the sidewall bottom chamber extends the combustor operating regime to the higher Reynolds number. This recirculation balanced the flame propagation and flow velocity at higher Reynolds numbers and strengthen the flame anchoring inside the bottom chamber. The modified flow aerodynamics enhanced the combustion sustainability of the miniature combustors. It is a critical parameter in designing new combustors with a wide range of operation regimes at a small scale.

Analysis of Air Flow, Air and Fuel Induction for Internal Combustion Engine

In an internal combustion engine, performance, efficiency and emission formation depends on the formation of air-fuel mixture inside the engine cylinder. The fluid flow dynamics plays an important role for air-fuel mixture preparation to obtain the better engine combustion, performance and efficiency. This review article discuss the rotating flow (swirl and tumble) in premixed spark-ignition engine and its effect on turbulence generation and flame propagation. Rotating flow can substantially increase turbulence intensity for the duration of the combustion period. This review paper discusses the in-cylinder swirl and tumble flow that affects air induction during the combustion process in internal combustion engine. Alternatively, this study using computer simulation (Computational Fluid Dynamic, CFD) which offer the opportunity to carry out repetitive parameter studies. An integration-type flowmeter (IFM) also has been used which consists of ultrasonic flowmeter, that integrates the flowrate during the intake process, gives accurate measurements regardless of sampling time and frequency. Research parameter in this study was swirl and tumble that represents the fluid flow behavior occurred inside combustion chamber. Fuel injection and air mass also were the important parameters that have been discussed about in air induction process. The results obtain from the numerical analysis can be employed to examine the homogeneity of air-fuel mixture structure for better combustion process and engine performance.

Fuzzy Logic Control System for Fuel Mixture Quality in Spark Ignition Engines.(Dept.M)

Spark ignition engine performance and exhaust emissions are strongly affected by the fuel/air ratio used. A considerable amount of investigations have been carried out by engine manufacturers to control engine performance and meet exhaust emission standards of governmental agencies by developing control systems for some operating variables such as ignition timing(IT), Fuel Air Ratio(FAR), and Exhaust Gas Recirculation (EGR) This paper presents a fuzzy control system that measures exhaust temperature and operates a needle valve on the engine earburetor jet that enables the fuel to air ratio lo oscillate about a desired value. A group of experiments have been carried out to obtain the relationship between fuel to air ratio or (ɸ), Exhaust temperature and exhaust emissions. A group of fuzzy logic rules which relate exhaust temperature, to the desired speed with the position of a needle valve actuated by a stepping motor are prop osed. A beneficial of fuzzy control method was that the rules determined the characteristics of control system are interpreted by the operator. Experimental and simulated results show that the prop osed fuzzy system improves the fuel/air mixture quality.

Fuel consumption and air emissions in one of the world's largest commercial fisheries.

The little information available on fuel consumption and emissions by high seas tuna fisheries indicates that the global tuna fleet may have consumed about 2.5Mt of fuel in 2009, resulting in the production of about 9Mt of CO2-equivalent greenhouse gases (GHGs), i.e., about 4.5-5% of the global fishing fleet emissions. We developed a model of annual fuel consumption for the large-scale purse seiners operating in the western Indian Ocean as a function of fishing effort, strategy, and vessel characteristics based on an original and unique data set of more than 4300 bunkering operations that spanned the period 2013-2019. We used the model to estimate the total fuel consumption and associated GHG and SO2 emissions of the Indian Ocean purse seine fishery between 1981 and 2019. Our results showed that the energetic performance of this fishery was characterized by strong interannual variability over the last four decades. This resulted from a combination of variations in tuna abundance but also changes in catchability and fishing strategy. In recent years, the increased targeting of schools associated with fish aggregating devices in response to market incentives combined with the IOTC management measure implemented to rebuild the stock of yellowfin tuna has strongly modified the productivity and spatio-temporal patterns of purse seine fishing. This had effects on fuel consumption and air pollutant emissions. Over the period 2015 to 2019, the purse seine fishery, including its support vessel component, annually consumed about 160,000t of fuel and emitted 590,000t of CO2-eq GHG. Furthermore, our results showed that air pollutant emissions can be significantly reduced when limits in fuel composition are imposed. In 2015, SO2 air pollution exceeded 1500t, but successive implementation of sulphur limits in the Indian Ocean purse seine fishery in 2016 and 2018 have almost eliminated this pollution. Our findings highlight the need for a routine monitoring of fuel consumption with standardized methods to better assess the determinants of fuel consumption in fisheries and the air pollutants they emit in the atmosphere.

Partitioning behaviors of zinc in eight coal-fired power plants with different fueled coals and air pollution control devices.

Emissions from coal-fired power plants (CFPPs) have a negative impact on the environment and metals are one of the categories of substances that have received considerable attention. In the present study, atmospheric zinc (Zn) emissions from eight CFPPs with different kinds of boilers and air pollution control devices (APCDs) in Guizhou Province, Southwest China, were investigated as well as the partitioning of this metal among boilers and APCDs. During the investigation of a CFPP, samples were taken of input and output materials during the same period. Our results give a Zn content of 32-165 mg kg-1 for feed coal, 52-237 mg kg-1 for bottom ash, 108-725 mg kg-1 for fly ash, 1.2-6.0 mg kg-1 for limestone, 1.6-7.3 mg kg-1 for gypsum, and 1.39-7.06 μg Nm-3 for stack gas. Most of the zinc content in the feed coal goes with the flue gas after combustion and amounts to 94.2-96.1% and 60.5-78.1% for pulverized coal-fired boilers (PC) and circulating fluidized bed boilers (CFB), respectively. Based on input Zn, a larger share (80.8-96.4%) ends up the captured fly ash of PC boilers than the case of CFB boilers (66.1-73.6%). In turn, a minor portion is captured into the flue gas desulfurization gypsum, while we found a maximum of 0.05‰ is emitted into the atmosphere. The atmospheric emission factors (EMFs) of Zn for the eight CFPPs are 7.55-57.22 mg ton-1 coal, 4.17-22.75 μg (kWh)-1, or 0.39-2.36 g TJ-1 using different benchmarks. Overall, the calculated emission factors here are distinctively low with the upgrading of APCDs in recent years. An estimation of 1276 ± 1047 kg year-1 (range: 498-3777 kg year-1) of Zn is emitted into the atmosphere from the CFPPs of Guizhou Province in 2017 by coupling the EMFs obtained from this study and the coal consumption by this category of power plants.

Bahaya Kesehatan dan Keselamatan Kerja Penggunaan Kompor Gas Dua Tungku Pada Industri Berskala Kecil Menggunakan Metode FMEA (Failure Modes and Effects Analysis)

Penggunaan bahan kompor gas bermanfaat dari sisi ekonomi dan efisiensi, namun di sisi yang lain meninggalkan permasalahan terutama pada aspek Ksehatan dan Keselamatan Kerja. Kasus kegagalan pada pemanfaatan kompor gas yang menyebabkan ledakan dan kebakaran disebabkan oleh berbagai faktor. Usaha telaah kritis terkait risiko dalam pemanfaatan dapat dilakukan dengan menggunakan penilaian risiko yang sistematis terkait kegagalan sistem pemanfaatan suatu alat yaitu FMEA (Failure Modes and Effects Analysis). Tujuan penelitian ini adalah untuk lakukan analisis risiko bahaya kesehatan dan keselamatan kerja penggunaan kompor gas dua tungku sehingga mendapatkan prioritas masalah yang perlu diwaspadai. Penelitian ini merupakan penelitian deskriptif dengan pendekatan kuantitatif. Penelitian dilakukan di Industri berskala kecil di Kabupaten Jember, Provinsi Jawa Timur di bulan Maret-Mei 2020. Analisis dan pengolahan data serta penentuan prioritas risiko dilakukan dengan pedoman FMEA. Hasil penelitian menunjukkan bahwa kompor gas dua tungku terdiri dari empat sistem yaitu sistem rangka kompor, sistem penyalaan burner dan pengaturan api. Sistem bahan bakar dan sistem pengaturan udara, dengan 12 subsistem dalam empat sistem tersebut. Penelitian ini menyimpulkan bahwa terdapat tiga risiko bahaya kesehatan dan keselamatan kerja pada penggunaan kompor gas dua tungku pada industri berskala kecil yaitu pertama bahaya pada sistem bahan bakar tepatnya subsistem regulator kompor, kedua bahaya kesehatan dan keselamatan kerja pada sistem bahan bakar tepatnya subsistem katup tabung gas dan ketiga bahaya kesehatan dan keselamatan kerja pada sistem kerangka kompor tepatnya pada sub sistem pan support. Saran yang diberikan kepada industri berskala kecil dan masyarakat pengguna kompor gas dua tungku adalah berperilaku aman dan selalu menjaga kondisi kompor agar tetap aman dengan memperhatikan hasil analisis bahaya yang telah dilakukan.

Analysis of the performance of a low-power atmospheric burner for gas appliances for households and their impact on the emission and stability of the burner

The paper presents results of theoretical numerical research dealing with CO and NOx emission performed in the process of optimization of the performance of low-power atmospheric burners. The theoretical part of this paper, whose main goals were better understanding of the complex issues of methodology and establishment of performance prediction and optimization of low-power atmospheric gas burner included numerical variation of independent parameters, such as burner geometry, the coefficients of primary and secondary air and different gaseous fuels including biogas. The findings of theoretically obtained performance prediction and optimization of atmospheric burners were experimentally investigated in purpose built test rigs for a number of variable parameters. The obtained results fully justified the proposed models of performance prediction and burner optimization.

Studying the influence of single droplets on fuel/air ignition in a high-pressure shock tube.

The interaction of fuel and lubricant droplets with gaseous fuel/air mixtures close to autoignition is relevant in the context of unwanted early autoignition in spark-ignition internal combustion (IC) engines. To study the influence of droplets on the ignition of fuel/air mixtures independent from the in-cylinder pressure/temperature history, the shock-tube technique in combination with an injection system was established, which enables the generation and injection of single droplets or droplet clusters of n-dodecane and lubricant base oil behind reflected shock waves at pressures and temperatures representative for the compression phase of IC engines. Injected droplets were imaged by high-repetition-rate laser-induced fluorescence. The ignition process was observed by imaging in the visible and UV simultaneously through the shock-tube end wall with a combination of color- and UV-sensitive high-repetition-rate cameras. It was found that the amount and composition of the injected liquid are important factors determining the extent of the interference with the ongoing autoignition of the premixed fuel/air bath gas. For a stoichiometric mixture of primary reference fuels (PRF95) in air, the droplets significantly accelerate ignition especially in the negative temperature coefficient regime at around 760 K. The comparison of the timing of local ignition and the occurrence of volumetric ignition indicates that only in cases where the surrounding gas is close to autoignition, the droplets can trigger early autoignition. This required temporal and spatial coincidence might explain the high level of randomness of early autoignition in engines.

Influence of Gaseous Hydrogen Addition on Initiation of Rotating Detonation in Liquid Fuel–Air Mixtures

Hydrogen is the most common molecule in the universe. It is an excellent fuel for thermal engines: piston, turbojet, rocket, and, going forward, in thermonuclear power plants. Hydrogen is currently used across a range of industrial applications including propulsion systems, e.g., cars and rockets. One obstacle to expanding hydrogen use, especially in the transportation sector, is its low density. This paper explores hydrogen as an addition to liquid fuel in the detonation chamber to generate thermal energy for potential use in transportation and generation of electrical energy. Experiments with liquid kerosene, hexane, and ethanol with the addition of gaseous hydrogen were conducted in a modern rotating detonation chamber. Detonation combustion delivers greater thermal efficiency and reduced NOx emission. Since detonation propagates about three orders of magnitude faster than deflagration, the injection, evaporation, and mixing with air must be almost instantaneous. Hydrogen addition helps initiate the detonation process and sustain continuous work of the chamber. The presented work proves that the addition of gaseous hydrogen to a liquid fuel–air mixture is well suited to the rotating detonation process, making combustion more effective and environmentally friendly.

Optimal Falling Track Design for Twice detonating Fuze of Double event Fuel air Explosive with High Speed

To prevent the initiation failure caused by the uncontrolled fuze and improve the weapon reliability in the high-speed double-event fuel-air explosive (DEFAE) application, it is necessary to study the TDF motion trajectory and set up a twice-detonating fuze (TDF) design system. Hence, a novel approach of realising the fixed single-point center initiation by TDF within the fuel air cloud is proposed. Accordingly, a computational model for the TDF motion state with the nonlinear mechanics analysis is built due to the expensive and difficult full-scale experiment. Moreover, the TDF guidance design system is programmed using MATLAB with the equations of mechanical equilibrium. In addition, by this system, influences of various input parameters on the TDF motion trajectory are studied in detail singly. Conclusively, the result of a certain TDF example indicates that this paper provides an economical idea for the TDF design, and the developed graphical user interface of high-efficiency for the weapon designers to facilitate the high-speed DEFAE missile development.

Combustion characteristics of mixtures of certain hydrocarbon fuels in air

A theoretical study of the combustion of hydrocarbon fuel mixtures in water heating unit was carried out. The effect of hydrogen impurities and propane-butane fuel on the optimal (α = 1) combustion of natural gas in air is established.

CFD Analysis of the Fuel–Air Mixture Formation Process in Passive Prechambers for Use in a High-Pressure Direct Injection (HPDI) Two-Stroke Engine

The research on two-stroke engines has been focused lately on the development of direct injection systems for reducing the emissions of hydrocarbons by minimizing the fuel short-circuiting. Low temperature combustion (LTC) may be the next step to further improve emissions and fuel consumption; however, LTC requires unconventional ignition systems. Jet ignition, i.e., the use of prechambers to accelerate the combustion process, turned out to be an effective way to perform LTC. The present work aims at proving the feasibility of adopting passive prechambers in a high-pressure, direct injection, two-stroke engine through non-reactive computational fluid dynamics analyses. The goal of the analysis is the evaluation of the prechamber performance in terms of both scavenging efficiency of burnt gases and fuel/air mixture formation inside the prechamber volume itself, in order to guarantee the mixture ignitability. Two prechamber geometries, featuring different aspect ratios and orifice numbers, were investigated. The analyses were replicated for two different locations of the injection and for three operating conditions of the engine in terms of revolution speed and load. Upon examination of the results, the effectiveness of both prechambers was found to be strongly dependent on the injection setup.

The Influence of Fuel–Air Mixture Preparation Quality in the Burner on the Fuel Combustion’s Completeness in the GTU Combustion Chamber

A method for determining the fuel and air mixing quality at the combustion chamber’s (CC) burner outlet in a natural gas fired, power-generating gas turbine unit is developed. Three types of burners differing from one another in the nozzle head design are experimentally investigated. The investigation was carried out on a facility in which carbon dioxide was used to simulate fuel. The field of СО2 concentrations in different sections was determined during the investigations. An experimental data-processing procedure for determining the mixing quality is developed. Firing tests of three burners in a single-burner compartment simulating the combustion liner were carried out. The experimental setup on which the tests were carried out and the single-burner compartment design are described. The concentrations of final gas mixture components, in particular, the concentrations of CO, О2, and СН in the combustion products, were determined using a Testo 350 gas analyzer. The obtained concentrations were used as the initial data for calculating the fuel combustion’s completeness. Based on comparison of the obtained experimental data, a dependence characterizing the effect of fuel-mixing quality on the fuel combustion completeness has been derived.

Photocatalytic oxidative desulfurization and denitrogenation for fuels in ambient air over Ti3C2/g-C3N4 composites under visible light irradiation

MXene Ti3C2 modified g-C3N4 composites were prepared and used in photocatalytic oxidative denitrogenation and desulfurization under visible light. The photocatalysis system adapted to oxidation of small molecular pyridine and thiophene for fuels in the ambient air without adding extra H2O2 or pure O2 oxidants. Structural and photoelectric properties of the photocatalysts were characterized and compared. In an optimal composite, g-C3N4 nanosheets were successfully intercalated by Ti3C2 layers to form an interfacial effect and heterojunction. Intercalation effect accelerated the photogenerated electrons transferring from g-C3N4 to Ti3C2, and inhibited the recombination of electron-hole pairs. Ti3C2/g-C3N4 composite exhibited enhanced photocatalytic performance, high mineralization efficiency, and good recyclability in the removal of pyridine and thiophene. Mechanism and DFT studies proposed that the holes acted as the major active species for the photocatalysis procedures to form the reactant intermediates, while the electrons and O2 generated superoxide radicals provided a promotion effect on the final conversions.

Prediction of Explosion Power of Fuel Air Mixture in Coal Mine by Improved BP Neural Network

In order to improve the feasibility and accuracy of predicting the explosion power of fuel air mixture, a method of BP neural network prediction is proposed by combining factor analysis method with BP neural network. Using factor analysis method, the original data of 9 fuel air mixture explosion power factors were processed by dimensionality reduction data, 2 common factors were obtained, and 2 common factors were substituted for 9 fuel air mixtures as input layer parameters of BP neural network. A prediction model of coal and gas outburst with the combination of factor analysis method and BP Neural network is established to predict the explosion power of fuel air mixture. The prediction model of the explosion power of the fuel air mixture is selected to verify the improved BP neural network prediction models, and the final results are as follows: The relative error range of four prediction samples is 0.16%-7.58%, all less than 10%. The improved BP neural network prediction method is used to solve the problem of the traditional BP neural network because of the excessive number of input layer parameters, low data processing efficiency, slow iteration rate and low precision, which provides a new research way for predicting the explosion power of fuel air mixture.

Numerical investigation of a confined diffusion flame in a swirl burner

In this study, combustion in confined burners, with confinement ratios equal to 1, 1.5, 2, and 3 were numerically investigated. A non-premixed swirling flame was generated by supplying the fuel, i.e. methane or propane, to a central gas outflow while air was supplied through screw-type swirl generator with six opening lobes. Swirling flame was confined inside a long confinement tube with various confinement diameters. Flame structure, fuel–air mixing efficiency, NOx and CO emissions were investigated in wide ranges of equivalence ratios (0.68–0.82), momentum ratios (0.002–0.006), and air flow Reynolds numbers (5400–6450). Fuel–air reaction was modelled using a 2-step reaction approach. The results showed that confinement ratio and momentum ratio played important roles in determining recirculation zone size and shape. For small confinement ratio, the central fuel jet penetrated the central recirculation zone while for confinement ratio equal to 3, this behaviour did not happen. Because of the high confinement and the partial combustion of the fuel, two streams occurred in the confinement tube—an outer stream with high oxygen content and an inner stream with high concentration of CO. It found that propane flame released more NOx and CO emissions than methane flame did, and NOx and CO concentrations at the burner exit were dependent on momentum ratio rather than confinement ratio. Increasing air flow, i.e. increasing Reynolds number, led to a reduction of NOx due to the formation of a stronger recirculation zone.

Combine Harvester Fuel Consumption and Air Pollution Reduction

Agricultural production has a major impact on the environment. Indeed, the emissions from agricultural machinery have a significantly negative impact on ambient air, thereby contributing to Climate Change. This study analyses combine harvesters and justifies their optimization in order to increase resource efficiency as well as reduce any negative impact on the environment. Data from 90 combine harvesters in Lithuania and Latvia from 2016 to 2018 is collected using telematics, and the parameters that directly influence engine exhaust emissions are analyzed, such as operation time, grain unloading method, fuel consumption, and auto-steering, according to the engine-operating modes of harvesting, transportation, and idling. Statistically reliable strong correlations can be found between harvesting time and idling time, as well as between fuel consumption during harvesting and idling modes. On average, roughly 20% of the operating time consists of idling and roughly 15% of transportation; moreover, roughly 14% of the diesel fuel is used per year in the aforementioned engine modes. In addition, the auto-steering function enables the efficient use of diesel fuel (average cost per combine harvester is reduced by 0.2 t year⁻¹), thereby reducing air pollution (pollution per combine harvester is reduced on average by 0.6 t year⁻¹). The results suggest telematics system data can be effectively used for data analysis, problem identification, and decision-making with respect to pollution prevention and optimizing combine harvester operation. Graphical Abstract

Experimental study on combustion characteristics of a CI engine runs on a renewable fuel

ABSTRACT Currently, the world is focusing on utilising biofuels as much as possible for internal combustion (IC) engine applications. Several strategies are being employed to improve fuel efficiency and decrease exhaust emissions of compression ignition (CI) engines which run on different biofuels. Fuel air mixture formation is one of the key aspects that influence engine behaviour in terms of combustion, emission, and performance of CI engines. In this research work, an attempt was made to induce air motion in a CI engine which was operated with an orange oil diesel (O-D) blend. For this purpose, a single cylinder, 4-stroke, air-cooled, direct injection (DI) diesel engine producing power of 4.4 kW at a constant speed of 1500 rpm was used. The piston of the engine was modified by two means to create turbulence; (i) piston with micro holes, and (ii) piston with micro holes and spiral grooves. The combustion characteristics of the test engine run on the O-D blend, without and with the change in piston geometries were evaluated, compared with the baseline diesel fuel operation, and presented in this paper.