The distribution characteristics and causes of casing deformation during hydraulic fracturing were investigated. Finite element models of a casing−cement sheath-formation assembly, considering a multi-stage fracturing process, were established. The axial displacement law of formation during multi-stage fracturing was analyzed. Furthermore, considering the existence of faults, the mechanism of casing deformation caused by fault slippage due to axial displacement was analyzed. Finally, the influence of fault parameters, as well as the casing’s geometry and mechanical parameters, on casing deformation were clarified. The results show that the casing deformation point is densely located near landing point A and sparsely located near toe point C. The entry of high-pressure fracturing fluid into the formation would reduce the effective stress of the formation and could even change it from compression to tension, which would mean that the formation in the fractured section would be stretched... [more]

The high cost of Lithium-ion battery systems is one of the biggest challenges hindering the wide adoption of electric vessels. For some marine applications, battery systems based on the current monotype topologies are significantly oversized due to variable operational profiles and long lifespan requirements. This paper deals with the battery hybrid energy storage system (HESS) for an electric harbor tug to optimize the size of the battery system. The impact of battery hybridization was investigated on three key performance indicators inclusive of cost, system efficiency, and battery weight. The design life of the battery system is considered to be 10 years, and NMC and LTO cell technologies are used as high-energy (HE) and high-power (HP) battery cells. The HESS design is based on a parallel full-active architecture with a rule-based energy management strategy. The results of this research indicate that battery hybridization can reduce the system cost by around 28% and 14% in comparis... [more]

Proton exchange membrane water electrolyzers (PEMWEs) coupled with renewable energy resources are considered to be a key technology for producing green hydrogen. However, the high current density PEMWE operation features remarkable voltage losses. A significant part of these losses is due to the mass transport resistance in the PEMWE. Even though the importance of mass transport resistance is widely recognized, it is still poorly understood. Currently, the two-phase transport through the anode porous transport layer (PTL) and catalyst layer is considered to be the main cause of the mass transport losses. In this work, a dynamic macroscopic mathematical model, coupling electrochemical reaction with mass transport through the PTL and flow channels, has been developed to study the two-phase flow in the PTL and mass transport losses of a PEMWE. The influence of the current density, inlet water flow rate, PTL structural parameters, and capillary pressure curve was evaluated. The existence o... [more]

Climate change and the energy crisis are two main problems that humanity is currently facing and that require immediate action [...]

Rainfall infiltration is one of the main triggers of inner dump slope failure in the process of mining coal. Changes in water content throughout the process of rainfall infiltration have rarely been studied. The reductions in soil strength due to water migration have seldomly been considered in the existing analytical solution of the safety factor (F.S) for unsaturated inner dump slopes in an open-pit mine. In this work, a new mechanical model was developed by improving the conventional analytical solutions of F.S for unsaturated inner dump slopes to accommodate water-induced degradation in the mechanical strength of waste material. Parameter analysis was carried out via a case study of the Shengli #1 open-pit coalmine. The results showed that the wetting front depth increased with increasing rainfall time, and the increasing rate was constant during the non-compressive infiltration stage, while it decreased gradually in the compressive infiltration stage. The F.S of the transition lay... [more]

Based on CiteSpace software, this paper reviews and analyzes the application articles of acoustic emission in coal from 2010 to 2020. In this paper, CiteSpace software visualizes 453 articles collected in the Web of Science core database. The cooperation networks between different countries, institutions, and authors are used to determine the connection of knowledge in papers. The keyword co-occurrence, keyword co-occurrence time zone map, and keyword clustering are used to determine the hot topics in the field. The cited collaborative network analysis reveals the important literature and the contribution of prominent authors in this area. In the future, for the research of acoustic emission in coal mining, compression tests will still be the main test methods. In terms of time domain parameters of acoustic emission, the application of ring counting, energy, waveform, and signal strength are very mature. The principal problem of acoustic emission location operation will become a focus... [more]

Determining residual oil saturation by the single-well chemical tracer test (SWCTT) is of key importance for assessing the potential of enhanced oil recovery (EOR) and developing EOR pilot projects. However, the test trials conducted since the first injections of tracer compositions until now have not resulted in a detailed analysis of the selection of candidates for single-well tracers and their limits of applicability in various reservoir conditions. The purpose of this study was to consider the influence of the structure on the kinetic and thermodynamic components of tracers to assess their application’s operating intervals. It is shown that the rate of single-phase and two-phase hydrolysis of the primary partitioning tracer makes it possible to predict the shut-in time by calculating when the tracer is injected at the reservoir temperature. The influence of the tracer structure during the extraction process with an increase in the hydrocarbon chain of the ester in a different range... [more]

The number of injector holes and the fuel-injection pressure in an internal combustion engine can affect engine performance and exhaust emissions. Conversion of a port-injection gasoline engine to an HCNG direct-injection engine improves engine performance and exhaust emissions. In addition, increasing the injection pressure helps to increase engine performance. In this study, AVL Fire software was used to perform simulation by certain adjustments. The injection pressure was applied in mods of 15, 20, and 25 bars, the injector holes numbers were 3 and 6, the compression ratio changed from 10:1 to 14:1, and the amount of hydrogen enrichment to natural gas was in mods of 10%, 20%, 30%, and 40%. This paper discusses the items above with regard to power, torque, combustion chamber pressure, fuel conversion efficiency, and exhaust emissions. The result determined that increasing the number of injector holes improves the performance engine and reduces CO emission so that the contour plots co... [more]

The global production and consumption of plastics have continued to increase. Plastics degrade slowly, causing persistent environmental pollution Developed waste plastic recycling methods are discussed in this report, with a focus on the dissolution/reprecipitation technique to restore low-density polyethene (LDPE) wastes. Aspen HYSYS is used to simulate the recycling of waste LDPE. Turpentine/petroleum ether (TURP/PetE) is chosen as solvent/non-solvent with fractions proved efficient through laboratory experiments. PetE is selected to be the non-solvent used for the precipitation of pure LDPE. The feedstock is assumed to be LDPE products containing additives such as dye. The simulation model developed estimated a pure LDPE precipitate recovery with a composition of 99% LDPE with a flowrate of 1024 tonnes per year. In addition, Aspen HYSYS could approximate a rough cost estimate that includes utility cost, installation cost and other factors. Technical challenges were eliminated, and s... [more]

This work focuses on the energy and economic evaluation of a power generation system composed of a downdraft gasifier and gas microturbine. The gasification process was studied using wood pellets as fuel, while the influence of two gasification agents (air and oxygen-enriched air) on parameters, such as low heating value (LHV), composition, and yield of syngas, were analyzed. The syngas produced from oxygen-enriched air gasification in a downdraft gasifier had an LHV higher than 8 MJ/Nm3, being suitable to be supplied in the gas microturbine. Subsequently, syngas use in the gas microturbine was evaluated, and the results demonstrated that microturbine efficiency dropped from 33.00% to 21.35%, while its power decreased from 200 kW to 81.35 kW. The power generation system was modeled using Aspen Plus® v 11.0 software and validated using results obtained from published experimental studies. Accordingly, the integrated generation system presented an overall efficiency of 11.82% for oxygen-... [more]

The vertical heterogeneity of continental shale reservoirs is strong, the difference between lithology and stress between layers is large, the weak interface between layers develops, and the hydraulic fracture penetration and expansion are difficult, resulting in poor fracturing transformation effect. In view of this, based on the finite element and cohesive element method, this paper established a fluid-solid coupling model for the hydraulic fracture propagation through the continental shale and studied the control mechanism and influence law of various geological and engineering parameters on the hydraulic fracture propagation through the continental shale reservoir using single factor and orthogonal test analysis methods. Interfacial cementation strength between high layers, high vertical stress difference, low interlaminar stress difference, low tensile strength difference, low elastic modulus difference, high pressure fracturing fluid viscosity, and high injection displacement are... [more]

Heavy oil and natural bitumen resources in carbonate formations are huge and considered as the promising alternative energy resource to the conventional crude oils. However, the production of such resources is challenging due to the low permeability, high viscosity and significant content of resins and asphaltenes in the composition of heavy oil and natural bitumen. The combination of thermal, chemical and gas enhanced oil recoveries can be a promising method to unlock and upgrade heavy oil and natural bitumen in carbonate reservoirs. In this paper, we propose a novel in-situ liquid-phase oxidation of light hydrocarbons for a revolutionary thermo-gas-chemical enhanced oil recovery method, which can be applied in carbonate heavy oil reservoir formations. It is assumed that the oxidation process is carried out in a downhole well reactor, the products of which are a high temperature mixture of organic carboxylic acids and organic solvents. Here, we present the results of laboratory invest... [more]

Cooling structures of gas turbine blades have become more complex to achieve a better cooling effect. Therefore, heat transfer analysis tools with higher accuracy and efficiency are required to verify the effectiveness of cooling designs and continuously improve the design. In this work, a data-driven method is combined with a decoupled conjugate heat transfer analysis. The analysis object is a typical air-cooled gas turbine first-stage vane with film cooling, impingement cooling, and pin-fin cooling. In addition, a conventional 3-D conjugate heat transfer simulation of the vane was executed for contrast. Results show that this method shortens the time of the heat transfer analysis process significantly and ensures accuracy. It proves that the data-driven method is effective for the evaluation of a modern gas turbine cooling design and is an improvement compared to the traditional three-dimensional heat transfer analysis method.

From the perspective of pollution, economics, and product quality, it is very important to find an efficient way to minimize the sulfur content of petroleum products such as gasoline and diesel. In this work, an effective, inexpensive, and simple oxidative desulfurization system based on hydrogen peroxide activation by three dicarboxylic acids which have different carbon numbers (i.e., malonic acid, succinic acid, and glutaric acid) was utilized for the desulfurization of a real diesel sample with high organic sulfur-containing compounds. The desulfurization process was based on the oxidation of sulfur compounds in diesel fuel to the corresponding sulfones followed by acetonitrile extraction of the sulfones. To select the optimal experimental conditions, the effects of several parameters, including temperature, catalyst H2O2 dosages, and treatment time, were investigated. The results showed that the developed system was effective in desulfurizing real diesel fuel with high sulfur conte... [more]

Guide vanes (GVs) are installed between the runner and the stay vanes for flow guidance and discharge regulation in reversible pump-turbines. The unstable torsional self-excited vibration of the guide vane (GV) may occur when running at small guide vane opening angles during the transient operations involving pump flow. In addition, the double-stage radial vanes may induce complex flow in the vanes and influence the stability of torsional self-excited vibration of the guide vane. In this study, numerical simulations were conducted at small guide vane opening angles in pump mode for two different guide vanes based on the three-dimensional computational fluid dynamics (CFD) method. The flow regime with a deflection was formed on the trailing edge with a circle in the vaneless region that rotated reversely against the runner rotation when operating at smaller guide vane opening angles for both of the two guide vanes. Based on this, the coupling simulations based on the CFD method with a s... [more]

This study presents an approach for targeted comminution of component mixtures within a wet-operated stirred media mill. In the first step, a general understanding of the interactions between individual components on the grinding result with mixtures could be gained with basic experiments and following our former research work. In particular, a protective effect of the coarser particles on the fines could be elucidated. These findings were used to develop a process for the production of a battery slurry containing fine ground silicon particles as well as dispersed carbon black and graphite particles. By a tailored sample preparation applying a combination of particle dissolution and separation, the particle size distributions of carbon black and graphite particles were analyzed separately within the produced battery slurries. Based on the selective particle size analysis, the slurry preparation could be transferred from a complex multistage batch process using a dissolver to a stirred... [more]

Thermally enhanced oil recovery methods, such as in situ combustion and steam injection, are generating considerable interest in terms of improving oil reserve exploitation and satisfying oil demand and economic growth. However, the early breakthrough of the in situ combustion front and the significant amount of heat loss associated with steam injection for deeper reservoir applications are the main challenges that require urgent solutions. Further data collection related to the effects of a reservoir’s physical and chemical properties, temperature, and pressure on in situ combustion front propagation and steam injection heat transfer inefficiency would be needed to achieve better reservoir oil recovery. Most studies have focused on the application of catalytic systems and the investigation of minerals’ effects on combustion front stabilization; however, the effect of clay interlayers’ minerals on the performance of in situ combustion is still poorly understood. This paper takes a new... [more]

The concentration of carbon dioxide in the atmosphere has been increasing since immediately after the boom of industrialization. Novel technologies are required for carbon dioxide (CO2) capture, storage, and its chemical conversion into value-added products. In this study, we present a novel in situ CO2 utilization method via a hydrogenation process in the presence of nickel tallates during steam-based enhanced oil recovery. The light n-alkanes are the preferred products of in situ catalytic hydrogenation of CO2 due to their effective solubility, viscosity-reducing capacity, and hydrogen-donating capacity. A nickel tallate was evaluated for its carbon dioxide hydrogenation and oil-upgrading performance at 300 °C. The results showed that the content of saturated and aromatic fractions increased, while the content of heavier fragments decreased. Moreover, the relative content of normal C10−C20 alkanes doubled after the catalytic hydrogenation of CO2. Despite the noncatalytic hydrogenatio... [more]

is an important microbial organization involved in ethanol synthesis. Mutant strains that can withstand multiple pressures during this process are critical to the industrial development of biofuels. In this study, a dual high-throughput screening method of Triphenyl-2H-tetrazoliumchloride (TTC)-based macroscopic observation and the reaction of ferric nitrate with pyruvate (or pyruvate radical ion) in fermentation broth was used. Using this, an S. cerevisiae mutant library that could tolerate 381 g/L sucrose was established by ARTP random mutation and adaptive evolution to select the best strain; its ethanol yield was increased by an additional 20.48%; and the sucrose utilization rate was 81.64%. This method is specific to the selection of strains with increased ethanol production.

The application of direct injection (DI) technology can effectively improve the atomization effect of heavy fuel to reduce the fuel loss of heavy fuel engines (HFE). The fuel spray characteristics directly affect the combustion performance of the engine. To investigate the atomization process and evaporation characteristics of heavy fuel in-cylinder for an air-assisted direct injection (AADI) engine, a simulation calculation model of AADI HFE was established with the use of a computational fluid dynamics tool. The air-assisted injector model and the one-dimensional performance calculation model were verified by test data. The influences of injection timing and injection pressure on the spray characteristics and mixture formation in the engine cylinder were discussed. The results show that the mixture concentration distribution is uniform after the injection timing is advanced, and the mass fraction of the fuel evaporation increases. The earlier injection timing can provide the fuel wit... [more]

In the present study, the performance of the Savonius wind turbine in designs with dual turbines rotating opposite to each other was examined. To improve the performance of the Savonius wind turbine in the dual turbine design, a triangular plate was placed in front of the turbines. The effects of the geometric parameters of this triangular plate which was placed on the turbine performance were studied. The numerical analyses performed were confirmed by the experimental data of a previous study in the literature. The performance values of Savonius wind turbines were analyzed by numerical analysis, the accuracy of which was proven by experimental data. ANSYS Fluent, a computational fluid dynamics (CFD) program, was used for the performance analysis. In the first stage, the maximum power coefficient (Cp) of the conventional Savonius wind turbine was obtained around 0.17. With the optimum geometric parameter studies, the maximum power coefficient of the Savonius wind turbine in the triangu... [more]

Viscosity, density, and interfacial tension of three binary systems (carbon dioxide−isopropanol, argon−isopropanol, and sulphur hexafluoride−isopropanol) were measured at temperatures of 313.15 K and 333.15 K and at pressures up to 100 bar for carbon dioxide, and for argon and sulphur hexafluoride up to 500 bar. A vibrating tube densimeter method has been used for density measurements and a variable-volume high-pressure optical view cell with some modifications for the other measurements. The results showed that pressure does not have a high impact on viscosity. Density is found to be a linear function of pressure and temperature and the densities of the investigated binary systems increase with pressure and decrease with temperature. Interfacial tension decreased with the elevated pressure at a constant temperature for all the investigated systems. Accurate prediction of thermodynamic and mass transfer data is fundamental in various engineering and industrial operations to design proc... [more]

In this paper, the co-combustion behavior of the walnut shell, biochar, and coal, and the respective binary and ternary blends were investigated by thermogravimetric analysis (TGA) in the oxy-fuel atmosphere (21% O2/79% CO2). The combustion reactivity of coal was similar to biochar but lower than that of the walnut shell. The presence of the walnut shell improved the combustion performance of coal and biochar. The interaction between only biochar and coal was inhibited in the binary blends. The presence of the walnut shell in the ternary blend covered up the inhibition between biochar and coal. The average activation energy of each sample was obtained using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) kinetic models. The results of this study provide a reference for the rational utilization of biomass and biochar and the practical improvement of the thermal conversion efficiency of coal.

More energy-efficient industries could reduce the problems of pollution, global warming, energy security, and fossil fuel depletion, including processing waste into raw materials and more efficient energy cogeneration. This research project considers the novelties of the upgraded electricity cogeneration technique, including one open gas turbine during the high-pressure product reaction loop and a second turbine during the exhaust gas for co-product production with only one compressor. The upgraded electricity cogeneration was carried out in two steps and based on the productive use of otherwise useless polyethylene waste, flue gas, and wood. The first step can simulate the simulation model from the existing product production with well-known technology and process units using the Aspen Plus® simulator. The maximum available electricity cogeneration can previously be determined from the thermodynamics of the products and co-products, and an existing energy unit’s characteristic capacit... [more]

Probability distributions perform a very significant role in the field of applied sciences, particularly in the field of reliability engineering. Engineering data sets are either negatively or positively skewed and/or symmetrical. Therefore, a flexible distribution is required that can handle such data sets. In this paper, we propose a new family of lifetime distributions to model the aforementioned data sets. This proposed family is known as a “New Modified Exponent Power Alpha Family of distributions” or in short NMEPA. The proposed family is obtained by applying the well-known T-X approach together with the exponential distribution. A three-parameter-specific sub-model of the proposed method termed a “new Modified Exponent Power Alpha Weibull distribution” (NMEPA-Wei for short), is discussed in detail. The various mathematical properties including hazard rate function, ordinary moments, moment generating function, and order statistics are also discussed. In addition, we adopted the... [more]