Fuel Gas Research Articles

Two- and Three-Stage Natural Gas Combustion System—Experimental Comparative Analysis

The use of fuels with tendencies to reduce carbon dioxide emissions, particularly gaseous fuels, and improve combustion systems is one of the directions for increasing an internal combustion engine’s attractiveness as a power source. This article presents the effects of combining natural gas combustion with a multi-stage combustion system. A two- and three-stage lean charge combustion system was proposed in order to increase the energy system efficiency. In order to achieve this, a single-cylinder test engine was used, with two interchangeably implemented combustion systems. The tests were carried out with two values of the excess air coefficient (λ = 1.3 and λ = 1.5), as well as two different fuel dose values (qo = 0.35 and 0.55 mg/inj), injected into the prechamber at the same indicated mean effective pressure value (IMEP = 6.5 bar) and the same engine speed (n = 1500 rpm). Based on the obtained research results, it was found that the use of a three-stage system limited the maximum combustion pressure and heat release rate due to the increased resistance of flows between the chambers. At the same time, it was found that the increase in the engine’s indicated efficiency took place in a two-stage system, regardless of the excess air coefficient. Changing the dose of fuel fed into the prechamber significantly affects the engine performance (and efficiency) but only in the two-stage combustion system.

Green synthesis of Cu-Mo promoted Fe catalyst for production of the gaseous and liquid fuels through Fischer-Tropsch synthesis

Designing a novel Fe catalyst with improved selectivity to light olefins and heavier hydrocarbons attracts great attention for Fischer-Tropsch synthesis (FTS) as an alternative clean energy resource. In this work, a highly efficient Cu-Mo promoted Fe catalysts supported on activated carbon with engineered features from biomass were synthesized and tested for FTS under relevant industrial conditions (300 °C, 2 MPa, and 2000 h−1). Optimization of the Fe, Mo, and Cu loadings led to a significant increase in CO conversion (from 46.7% for unpromoted to 78.8% for Cu-Mo promoted catalysts). Light olefin selectivity for the promoted catalysts was remarkably enhanced to 33.2% and 25.0% for Cu and Mo-promoted catalysts, respectively. The improved selectivity to light olefin can be attributed to the weakened basicity of iron sites for promoted catalysts. Improved C5+ selectivity on the other hand, can be assigned to the contribution of Fe carbides with higher C:Fe ratio in the structure of the optimized catalyst. The presence of Mo carbides was confirmed by XPS, XRD, and XANES results, manifesting the contribution of Mo in the catalytic activity of the optimized catalyst. The superior selectivity to both light olefins and C5+ hydrocarbons disclosed that the prepared catalyst could be an ideal candidate for industrial iron-based FTS catalyst in future to modulate the products distribution.

Overview of Energy Harvesting Technologies Used in Road Vehicles

Road transport is one of the most important factors for the national economy due to its universality and comprehensive possibilities of transporting people and goods. Unfortunately, from the energy point of view, it is also the most cost-intensive and has a negative influence on the natural environment. For these reasons, issues related to limiting the use of conventional fuels are very important, which results in reducing emissions from this sector, as well as reducing transport costs. This article presents currently used energy sources for propulsion of road vehicles, including fossil and alternative fuels, gaseous fuels and other energy sources such as fuel cells. The following section presents technologies that allow to recover some of the energy lost in motor vehicles and internal combustion engines used for their propulsion. The principle of operation of these solutions, their structure and their main features are presented. The last part focuses on discussing and identifying the most universal technologies for energy harvesting in vehicles and showing further directions of energy development in the automotive sector.

Effect of water acidity on the growth performance, survival, and hematology condition of the barramundi fish Lates calcarifer (Bloch, 1790) fingerling

Global warming is caused by increased carbon emissions into the atmosphere resulting from burning oil, gas, and other fossil fuels. Subsequently, the carbon gas enters the waters through a diffusion process facilitated by the concentration of gases in the air, which is higher than in the waters. The outcome of this process is a decrease in water acidity, leading to a lower pH, which can disrupt the life of aquatic biotas. Therefore, this study aims to analyze the effect of decreasing of pH on the growth, survival, and physiological conditions of barramundi (Lates calcarifer). To achieve this objective, seven pH levels were tested, namely pH of 7.24 (control), pH 6.74, pH 6.24, pH 5.74, pH 5.24, pH 4.74, and pH 4.24. Every treatment was performed with four replications, and the fish was reared for 30 days in the respective tested pH. The reared madia is sea water with a salinity of 22 ppt. The experiment was conducted in the laboratory of fish breeding Faculty of Marine and Fisheries, Universitas Syiah. The results showed that a decreasing in pH had a significant effect on the growth performance and hematological condition of barramundi (P0.05), but its had no significant effect on survival (P0.05). The experimental fish could survive at pH 4.24, but their growth and hematological conditions were disrupted below 6.24. Therefore, it was concluded that the lower threshold value of pH for barramundi was 6.24.Keywords:Global warmingOcean aciditypHFisheries productionPhysiological disturbance

Real-Time Simulation of CNG Engine and After-Treatment System Cold Start Part 1: Transient Engine-Out Emission Prediction Using a Stochastic Reactor Model

<div class="section abstract"><div class="htmlview paragraph">During cold start of natural gas engines, increased methane and formaldehyde emissions can be released due to flame quenching on cold cylinder walls, misfiring and the catalyst not being fully active at low temperatures. Euro 6 legislation does not regulate methane and formaldehyde emissions. New limits for these two pollutants have been proposed by CLOVE consortium for Euro 7 scenarios. These proposals indicate tougher requirements for aftertreatment systems of natural gas engines.</div><div class="htmlview paragraph">In the present study, a zero-dimensional model for real-time engine-out emission prediction for transient engine cold start is presented. The model incorporates the stochastic reactor model for spark ignition engines and tabulated chemistry. The tabulated chemistry approach allows to account for the physical and chemical properties of natural gas fuels in detail by using a-priori generated laminar flame speed and combustion chemistry look-up tables. The turbulence-chemistry interaction within the combustion chamber is predicted using a K-k turbulence model. The optimum turbulence model parameters are trained by matching the experimental cylinder pressure and engine-out emissions of nine steady-state operating points.</div><div class="htmlview paragraph">Subsequently, the trained engine model is applied for predicting engine-out emissions of a WLTP passenger car engine cold start. The predicted engine-out emissions comprise nitrogen oxide, carbon monoxide, carbon dioxide, unburnt methane, formaldehyde, and hydrogen. The simulation results are validated by comparing to transient engine measurements at different ambient temperatures (-7°C, 0°C, 8°C and 20°C). Additionally, the sensitivity of engine-out emissions towards air-fuel-ratio (λ=1.0 and λ=1.3) and natural gas quality (H-Gas and L-Gas) is investigated.</div></div>

Reaction kinetics for hydrothermal liquefaction of Cu-impregnated water hyacinth to bio-oil with product characterization

Hydrothermal liquefaction is a promising technology for the conversion of biomass to bio-oil and gaseous fuels. In the present work, isothermal hydrothermal liquefaction experiments of Cu-impregnated water hyacinth were conducted at 280 °C and investigated the effect of reaction time (10 min to 45 min) on bio-oil, carbon hybrids, aqueous products, and gas yields. A short residence time of 15 min was found to be optimum to achieve a maximum total bio-oil yield of 34.82% and analyzed by GC-MS and NMR for identification of compounds. Solid residues were analyzed by FESEM, XPS, XRD, and BET for morphological study, Cu loading, and its transition in the hydrothermal environment. Based on experimental data, reaction kinetics was developed and compared for hydrothermal liquefaction of Cu-impregnated water hyacinth with raw water hyacinth to predict the influence of Cu metal on reaction rate constants during hydrothermal liquefaction. From the kinetic modeling, it was found that the presence of Cu promoted the biomass conversion to bio-oil with light oil to heavy oil ((k4) 0.24404 min−1) conversion being the dominating reaction path. In contrast to catalytic degradation, the light oil conversion to aqueous phase components with a rate constant of 0.26323 min−1 is the most prevailing step for non-catalytic hydrothermal liquefaction.

Study of the Technical-Economic Feasibility of a Pyrolysis/Gasification Plant for the Generation of Liquid Gas Fuels from Plastic Waste

Pyrolysis can offer a practical environmental solution for recycling plastic waste, converting it into liquid and gaseous fuels of high commercial value. This article proposed the simulation in Aspen Plus® of a pyrolysis/gasification plant, having plastic residues and residual soybean oils as raw material. The products generated in the gasifier are bio-oil and synthesis gas, which can be converted into ethylene and gasoline in reactors. To calculate the plant’s cost of capital, the Lang Method was used. The economic indicators NPV, IRR, PI, and Payback determined the project’s viability. The works show that the current scenario studied has economic viability, but better results can be achieved with increasing project maturity.

The Influence of Heat Recirculation Segment of Meso-Scale Combustor o Gas and Liquid Fuel Inside Microscale Combustor

This study aims to determine the effect of heat recirculation segments configuration on the stability of the flame. Mesoscale combustor used is made from duralumin-quart glass tube, and Ø 3.5 mm diameter combustion chamber. The heat recirculation segments part is made of duralumin as a segment of evaporation and air-fuel mixing. Combustor A has heat recirculation segments length of 7 mm, while combustor B has a heat recirculation segments length of 10 mm. The fuel used is liquid hexane and butane gas fuel. The results showed, the stability of hexane flame in combustor A between the equivalent ratio of ɸ 0.73-1.28 temperature can reach 803.8oC. Combustor B is stable at an equivalent ratio of ɸ 0.76-0.98 to a temperature of 580.9oC. Furthermore, for butane flames; combustor A, stable in the range of ɸ 0.68-1.31 temperature to 931.3oC. Combustor B has a stability range of ɸ 0.79-1.41 temperature reaches 857.2oC. Combustor A with a 7 mm heat recirculation segments length is proven to produce wider flame stability, using both liquid fuel and gas. So, combustor A can be recommended to be applied to micro power generators. It should be noted that butane flames appear to have more flame stability than hexane flames. This is because gaseous fuels are more homogeneous (gaseous) so they are more quickly mixed with air.

Characteristics and circumstances of volatile solvent misuse-related death in Australia, 2000–2021

Introduction Volatile solvent misuse-related death is associated with neuropsychiatric, cardiovascular, respiratory and renal pathology, as well as sudden death. The study aimed to determine: (1) the circumstances of death and case characteristics of volatile solvent misuse-related death in Australia, 2000–2021; (2) the toxicological profile of cases; and (3) the major autopsy findings. Methods Retrospective study of volatile solvent misuse-related death in Australia, 2000–2021 retrieved from the National Coronial Information System. Findings One hundred and sixty-four cases were identified, 79.9% male, mean age 26.5 years (8.5% aged 40 years or older). Circumstances of death were unintentional toxicity (61.0%), unintentional asphyxia (20.1%), intentional self-harm (12.2%) and traumatic accident (6.7%). The most commonly reported acute presentation prior to death was sudden collapse (22 of 47 witnessed events). The most frequently used solvents at the fatal incident were gas fuels (35.4%), gasoline (petrol) (19.5%) adhesives/paints (19.5%), aerosol propellants (12.8%), and volatile anaesthetics (12.8%). The most commonly detected volatile substances were butane (40.7%), toluene (29.6%), and propane (25.9%). Cannabis was present in 27.6% and alcohol in 24.6%. The prevalence of acute pneumonia amongst autopsied cases was low (5.8%) which, together with reports of sudden collapse, suggests that in many cases, death was extremely rapid. There were low levels of major organ pathology. Conclusions While the average age of volatile solvent misuse-related death was in the mid-twenties, a substantial proportion occurred amongst people aged 40 years or older. Reflecting availability, gas fuels predominated. In many cases, death appeared to have been rapid.

Design of the shattered pellet injection system for ASDEX Upgrade

A new shattered pellet injection system was designed and built to perform disruption mitigation experiments on ASDEX Upgrade. The system can inject pellets with diameters of 1, 2, 4, or 8 mm with variable lengths over a range of L/D ratios of ∼0.5–1.5. By using helium or deuterium as propellant gas, the pellets can be accelerated to speeds between 60 and 750 m/s. The velocity range slightly depends on the pellet mass. The injection system is capable of preparing three pellets in separate barrels at the same time. Once accelerated by the propellant gas pulse, the pellets travel through one of three parallel flight tubes. Each flight tube is separated into three sections with increasing diameters of 12, 14, and 16 mm. Two gaps between the sections allow for removal of the propellant gas by expansion into two separate expansions tanks (0.3 and 0.035 m3), pellet observation in the first gap and the torus gate valve in the second. Each flight tube end is equipped with an exchangeable shatter head with different shatter angles, square or circular cross-section, and different lengths. The gas preparation and control systems allow highly automated pellet generation for precision of the pellet composition and an excellent reproducibility of shattered pellet experiments.

Molecular dynamics simulation of the gun barrel material erosion by propellant gas

The mechanisms of propellant gas chemical erosion on gun barrel materials are discussed creatively from a microscopic perspective of molecular diffusion and intermolecular interaction. The influence of high-temperature and high-pressure propellant gas atoms on the shallow surface microstructure of the barrel material is theoretically analyzed using the molecular dynamics simulation method, which can be used as a new idea for further study of the gun barrel erosion mechanism. The results show that the diffusion of the propellant gas atoms into the barrel material can be characterized by the significant longitudinal distribution characteristics of propellant gas atoms and the normal stress distribution characteristics in the surface layer of the barrel. Moreover, the diffusion ability of the propellant gas atoms in the surface of the barrel material decreases gradually with the increasing diffusion depth. Under the action of propellant gas atoms, the dislocation structure dominated by face-centered cubic structure (FCC) forms in the shallow surface of the barrel material. The production of initial erosion in the shallow surface of barrel materials can be predicted by the continual growth of the new structure and the stress distribution characteristics of the material. In addition, the temperature variation of the propellant gas contributes significantly to barrel material erosion.

Electrochemical production of hydrogen in reactors with reduced energy costs

To reduce climate change and carbonization of the atmosphere, today it is proposed to switch to green energy and use hydrogen as an energy source. When hydrogen burns, water forms, and carbon oxides are not released. Methods for processing solid, liquid, and gaseous fuels, as well as water electrolysis, are proposed for hydrogen production. The electrolysis of water ensures the production of chemically pure hydrogen. Its disadvantage is significant energy consumption and, as a result, high cost. The condition for the economically beneficial use of hydrogen is to reduce its cost to $1/kg. The existing designs of reactors and technologies for producing hydrogen do not allow achieving such efficiency, which is limited by the thermodynamics of the process. To reduce energy consumption, this paper proposes designs of reactors in which the process of oxygen evolution is replaced by the process of dissolving anodes made from production waste - iron and aluminium scrap. As a result of the measures taken, it is possible to reduce the voltage on the electrolyzers from 1.8 V to 0.5-0.6 V. This makes the hydrogen production process economically viable.

A Chamber Pressure Prediction Method Based on Strain Measurement of Composite Barrel Recoilless Guns

To predict the chamber pressure of positions corresponding to the strain data of the gun barrel’ outside walls, this study measures the chamber pressure and strain of different positions in a recoilless gun, and proposes a chamber pressure calculation method which is based on strain measurement of cylinder walls using the single-layer thin-walled cylinder theory and the plane strain-elastic stress solution for multi-layer orthotropic cylinders. Experimental results showed that the deformation of the recoilless gun at different positions was caused by varying factors. Specifically, chamber deformation was attributed to the expansion of high-pressure propellant gas, showing a strain curve similar to that of chamber pressure. The deformation of the barrel part between the chamber throat and the muzzle was first caused by band engraving and then by the expansion of high-pressure propellant gas. If the effect of band engraving was neglected, the changes of chamber pressure there were found to be well in line with the chamber deformation caused by propellant gas expansion. The calculation results revealed that the relative errors between the chamber pressure values predicted by the proposed method and the measured ones were in the range of 0.82%-7.88%, suggesting that the proposed method can effectively predict chamber pressure. The calculation error at the chamber position was large, reaching 7.88%, due to the neglect of the gap between the cartridge case and the chamber’s inside walls. The pressure in the barrel part between the chamber throat and the muzzle was satisfactorily predicted, with a minimum error of 0.82% and a maximum error of only 5.89% at the muzzle.

Effect of Rifling Height on Convective Heat Transfer Flux and Erosion for Cannon Barrel

The effect of rifling height on erosion for cannon barrel was studied in this paper. An erosion velocity kernel function which is an Arrhenius type function revealing thermal and chemical effects is proposed. The erosion function is employed in numerical simulations to obtain the erosion depth after several rounds for two kinds of gun barrels at commencement of full rifling. By comparing final erosion depths obtained by numerical simulations and firing tests, it can be concluded that heat transfer flux between propellant gas and barrel with different rifles are absolutely different. Then the effect of rifle height on convective heat transfer flux is discussed in this paper.

Predicting NOx Distribution in a Micro Rich–Quench–Lean Combustor Using a Variational Autoencoder

Micro gas turbines are widely used in distributed power generation systems. However, the combustion of gas turbine combustors produces a large amount of nitrogen oxides (NOx), which pollute the environment and endanger human life. To reduce environmental pollution, low-emission combustors have been developed. In recent years, there has been an increasing focus on the use of low-heat-value gas fuels, and it is necessary to study the NOx emissions from low heat value gas fuel combustors. Data-driven deep learning methods have been used in many fields in recent years. In this study, a variational autoencoder was introduced for the prediction of NOx production inside the combustor. The combustor used was a micro rich-quench-lean combustor designed by the research group using coal bed gas as a fuel. The internal NO distribution contour was obtained as the dataset using simulation methods, with a size of 60 images. The model architecture parameters were obtained through hyperparameter exploration using the grid search method. The model accurately predicted the distribution of NO inside the combustor. The method can be applied in the prediction of a wider range of parameters and offers a new way of designing combustors for the power industry.

Investigation of pressure gain characteristics of RDE with Tesla valve inlet scheme

Total pressure gain is one of the most significant performance metrics for rotating detonation engines. In this study, a Tesla valve is introduced with the intention of suppression of pressure feedback to improve the total pressure gain of RDE. A Tesla RDE has larger total pressure gain than a baseline RDE in some cases of 1.3Kg/s and 1.0Kg/s for A8/A3.2 of 0.25 because it can delay the onset of Longitudinal pulsed detonation (LPD). Compared with published data, kerosene/oxygen-enriched achieves slightly higher total pressure gain than gaseous fuels. The maximum total pressure gain measured using the Equivalent available pressure (EAP) is −6.84%. As injection stiffness decreases, total pressure gain increases towards zero. Injection stiffness tends to decrease with increasing velocity for the given mass flow rates of air and nozzle. The pressure of the combustor inlet is positively correlated with the product of the detonation wave velocity and the mass flux of the nozzle outlet. Values of outlet total pressure calculated using EAP and Mach corrected static pressure (MCSP) are nearly the same, and deviations of them are summarized. When the Mach number of the nozzle outlet and total pressure recovery coefficient are taken into consideration, MCSP decreases while EAP increases.

Development of electromagnetic pellet injector for disruption mitigation of tokamak plasma

Disruption remains to be a serious threat to large tokamaks like the International Thermonuclear Experimental Reactor (ITER). The injection speed of disruption mitigation systems (DMS) driven by high pressure gas is limited by the sound speed of the propellant gas. When extrapolating to ITER-like tokamaks, long overall reaction duration and shallow penetration depth due to low injection speed make it stricter for plasma control system to predict the impending disruptions. Some disruptions with a short warning time may be unavoidable. Thus, a fast time response and high injection speed DMS is essential for large scale devices. The electromagnetic pellet-injection (EMPI) system is a novel massive material injection system aiming to provide rapid and effective disruption mitigation. Based on the railgun concept, EMPI can accelerate the payload to over 1000 m/s and shorten the overall reaction time to a few milliseconds. To verify the injection ability and stability of the EMPI, the prototype injector EMPI-1 has been designed and assembled. The preliminary test has been carried out using a 5.9 g armature to propel a dummy pellet and the results suggest that the EMPI configuration has a great potential to be the DMS of the large scale fusion devices.

Development and approbation of an analytical method for the quantitative determination of carbon tetrachloride in freons used in the composition of medicines in the form of an aerosol

Aim to develop and test an analytical method for the quantitative determination of carbon tetrachloride in freons used in the composition of medicines in the form of an aerosol.
 Material and methods. Carbon tetrachloride (tetrachloromethane, Freon-10) - CCl4, M.m. = 153.81, heavy, colorless, volatile liquid with a sweet smell reminiscent of chloroform. Melting point - 22.96 С, boiling point - 76.75 C, relative density at 20 - [d]420 1.595. Poorly soluble in water (0.5 g/l), unrestrictedly miscible with alcohol, ether, acetone, benzene (chemically pure grade).
 To determine the tests for the presence and quantitative determination of carbon tetrachloride in propellant gases used in medicinal preparations, we chose the drug "Salbutamol-Pharmstandard". To identify and quantify carbon tetrachloride in propellants used in medicinal products, the gas-liquid chromatography method with electron capture detection with a capillary column was applied.
 Results. The developed method was used to determine carbon tetrachloride in the test preparation "Salbutamol". The results were statistically processed and showed that the content of carbon tetrachloride in the test preparation was 0.01580.0007 mg/l. The error of a single experiment with a confidence probability P = 95% was 4.42%
 Conclusion. We proposed a method for estimating the content of carbon tetrachloride impurities in aerosol dosage forms by gas-liquid chromatography with an electron capture detector. The technique involved the gas chromatographic separation of a sample, taken from an aerosol can, on a capillary chromatographic column. The most appropriate detector in this case turned out to be an electron capture detector.

Influence of pressure and sunflower husks ash as catalyst on tire-char steam gasification

Catalytic gasification of low-reactive waste fuels, like tire-char, with the use of a different type of waste as a cheap and efficient catalyst seems to be an up-and-coming solution; however, requiring selecting appropriate process conditions. Therefore, this study aimed to assess the effect of various amounts (0, 5, 10, 15 wt%) of waste-based catalyst (sunflower husks ash, SHA) and pressure on tire-char gasification with steam. Feedstock and catalyst were characterised, then physically mixed, and the prepared samples were subjected to steam gasification. The gasification measurements were performed at 800, 850, 900 and 1000 °C and the pressures of 0.5 and 1 MPa, using the thermovolumetric method based on an analysis of the composition of the resulting gas (this research focused on the main gas components, i.e. CO and H2). The obtained results showed that the selected tire-char was characterised by a high calorific value; however, it contained a high content of carbon and catalytically inert ash, which may affect its reactivity. In turn, sunflower husk ash selected as catalyst consisted mainly of catalytically active compounds of alkali and alkaline earth metals (in particular K2O), while at the same time a low content of acid components that inhibit the process. The gasification measurements proved that the character of curves of formation rates of CO and H2 differed, indicating different formation mechanisms. Moreover, pressure and catalyst addition affected the gasification process, especially at low temperatures (∼800–850 °C). In this temperature range, an increase in pressure, catalyst addition, and increasing its loading improved the conversion reaction rate and maximum carbon conversion, as well as hydrogen yields. In turn, an increase in pressure and the addition of catalyst positively affected the yield of carbon monoxide in almost the entire range of analysed temperatures, whereas the effect of catalyst was not significant. Finally, the analysis of kinetic parameters of carbon conversion reaction during steam gasification showed that the addition of catalyst reduced both activation energy and pre-exponential factor (the most significant reduction was observed when using 5 wt% of SHA), while the increase in pressure had an inverse effect on these parameters. Nevertheless, the obtained results show that steam gasification of tire-char at low temperatures, the pressure of 1 MPa and in the presence of 15 wt% of SHA may be an attractive way to efficiently obtain gas rich in hydrogen — one of the most promising future fuels.

Investigation of Biomass Fouling on Screw Feeder in Preconversion of Pyrolysis

Biomass is a source of renewable energy and can undergo thermochemical processes to be converted into gaseous and liquid fuels. Thermal decomposition-induced biomass fouling on the screw feeder is a major challenge in preconversion of pyrolysis, leading to plugging of the feed line. This work intends to gain fundamental understanding of the biomass fouling phenomena across the heat gradient on the screw feeder via a combination of materials characterization and thermal simulation. An actual screw feeder that failed because of biomass fouling was examined to reveal the deposit’s morphology, composition, and mechanical properties. Thermal simulations were developed for both the screw feeder and the wood particles being transported using a combined analytical and numerical approach. The simulated temperature profiles correlated well with the deposit observations, based on which potential mitigations were proposed from both the operation and screw design perspectives and supported by preliminary experimental validation.