Tight gas reservoirs are finding greater interest with the advancement of technology and realistic prediction of flow rate and pressure from such wells are critical in project economics. This paper presents a modified productivity equation for tight gas horizontal wells by modifying the mechanical skin factor to account for non-uniform formation damage along with the incorporation of turbulence effect in the near-wellbore region. Hawkin’s formula for calculating skin factor considers the radius of damage as a constant value, which is less accurate in low-permeability tight gas reservoirs. This paper uses a multi-segment horizontal well approach to develop the local skin factors and the equivalent skin factor by equating the total production from the entire horizontal well to the sum of the flow from individual segmented damaged zones along the well length. Conical and horn-shaped damaged profiles are used to develop the equivalent skin used in the horizontal well productivity equation.... [more]

In this work, the synthesis of a phosphorylated polyvinyl alcohol (p-PVA)/polyoxometalate (tungsto-phosphate) membrane for the BioGenerator, a bio-electrochemical energy storage technology, is reported. It was shown that bonding of lacunary tungsto-phosphate ions to the carbon skeleton of a polymer matrix results in an increase in proton conductivity of up to 2.7 times, compared to previously studied phosphorylated PVA membranes. Testing of the membrane in an actual Fe3+/H2 electrochemical cell showed that it performs significantly better (0.28 W·cm−2 at 0.79 A·cm−2) than the previously used commercial Selemion HSF (Japan) membrane (0.18 W·cm−2 at 0.60 A·cm−2).

A thermal equilibrium model is established to investigate the heat leak of a space liquid hydrogen tank under different thermal adiabatic structures. The feasibility of the common bulkhead tank in realizing thrust or rotation reorientation by evaporated exhaust gas has been systematically studied. The results indicate that the space radiation heat leak is the primary heat leak in spray-on foam insulation (SOFI) adiabatic tanks. However, the common bulkhead heat leak is dominant in the tank with multilayer insulation (MLI) or self-evaporation vapor cooled shield (VCS). For the continuous stable adiabatic exhaust, the tank with SOFI (over 114 W/m2) could realize reorientation with the acceleration of over 5.5 × 10−4 m/s2 generated by the exhaust. Meanwhile, the tank that adopted MLI or VCS (below 18 W/m2) struggled to achieve gas−liquid separation with the acceleration below 8.7 × 10−5 m/s2 generated by exhausting. The rotational angular velocity of the tank through exhausting increases... [more]

Using nanoindentation technology to analyze the hardness and elastic modulus distributions of the local microzones within materials, it can be determined that the case-carburized specimen is a composite of the carburized case and the pseudo-carburized material in the core. The overall mechanical behavior of the case-carburized material is much closer to that of the completely carburized material, indicating that the carburized case dominates the case-carburized material. Stress fatigue tests conducted on carburized tubular specimens, pseudo-carburized solid specimens, and case-carburized solid specimens showed that the fatigue performance of the completely carburized material is slightly lower than that of the pseudo-carburized specimens due to lower plasticity. However, the fatigue performance of the case-carburized specimens is significantly better than that of the two homogeneous materials. This could be attributed to the graded material behavior and the larger compressive residual... [more]

Using a high proportion of new energy is becoming the development trend of the modern power industry, with broad application prospects and potential threats to power system operation safety. This paper proposes a hybrid adaptive velocity update relaxation particle swarm optimization algorithm (AVURPSO) and recursive least square (RLS) method to quickly estimate the DSSR boundary using hyper-plane expression. Firstly, the operating point data in the high-dimension nodal injection space are analyzed using the AVURPSO algorithm to identify the key generators, equivalent search space, and critical points, which have relatively great effects on transient angle stability. The hyper-plane expression of the DSSR boundary, which matches the critical points best, is finally fitted by the RLS approach. Hence, the adopted algorithm is applied to rapidly approximate the DSSR boundary by hyper-plane expression in power injection spaces. Finally, the proposed algorithm is validated using a simulation... [more]

In this paper, the effect of nano-particles along with EGR rates was experimentally assessed on the performance and emission of a DI diesel engine fueled by biodiesel and ethanol. For this purpose, three levels of TiO2 nanoparticles (0, 40, and 60 ppm) were added to biodiesel/diesel blends in the proportions of 0, 10, and 20% biodiesel with ethanol at levels of 0, 4, and 6%. EGR rates were used at 0, 20, and 30%. A total of 31 fuel samples with different ethanol, biodiesel, TiO2 nano-additives, and EGR rates were tested at different speeds. The equation for this combination is BxEy + EGRw + TiO2z, where x, y, w, and z are the percentages of biodiesel, ethanol, EGR, and TiO2. The results showed that the mixture of B10E4 + EGR20 + TiO260, reduced the amount of NOx, CO, and HC by 10, 12.4, and 17%. Moreover, due to the significant reduction of emissions and performance improvement, the combinatory method of EGR−TiO2 nano-additives can be used as an effective formula for diesel engines fue... [more]

Although many biofuel blends have been proposed recently, comparisons of such blends are rarely investigated. Currently, it is extremely difficult to recommend one biofuel blend over another since comparisons are not carried out under the same engine conditions. In the current study, different biofuel blends in dual and ternary issues are compared together, as well as with conventional gasoline under the same engine conditions. Five different biofuel blends are considered, i-butanol (iB), n-butanol (nB), bio-ethanol (E), n-butanol−bio-ethanol (nBE), and i-butanol−bio-ethanol−gasoline (iBE) blends, at two different engine speeds (2500 and 3500 rpm/min). Additionally, the blends are compared in the average bases through wide engine speeds. The comparisons of blends are carried out via engine performance and emissions. The performance includes engine power, torque, and volumetric efficiency, while the emissions include CO, CO2, and UHC. Results showed that the E blends presented higher pe... [more]

Plasma electrolytic oxidation (PEO) was used to establish a porous metal oxide layer on various titanium and zirconium workpieces in the form of wires, porous tubes, and 3D-printed structures. The ultimate goal of the work was to create a layer with the desired characteristics over a catalyst support or metal membrane structures to improve the performance of the targeted high-temperature catalytic conversion or separation applications. In doing so, it was ensured that the PEO-treated layer could provide the desired morphology, thickness, and porosity needed for the final processing step, which is usually a conventional coating method. This addresses the limitations of ceramic structures, including their mechanical resistance, thermal resistance, and conductivity, and their potential for being functionalized and utilized for high-temperature applications. The entire experimental run was carried out using a 2 kilowatt (maximum output) AC-power source with a maximum current limit of 6.5 A... [more]

The petrochemical industry is a pillar industry for the development of the national economy affecting people’s daily living standards. Crude distillation process is the core and leading unit of the petrochemical industry. Its energy consumption accounts for more than 20% of the total energy consumption of the whole plant, which is the highest energy consumption link. A model based on the long short-term memory network (LSTM) is proposed in this paper to predict and analyze energy efficiency. This model extracts the complex relationship between many process variables and predicts the energy efficiency of the crude distillation process. Firstly, the process simulation of crude distillation is carried out. By adding random disturbance, the data set in different working conditions is obtained, and the difference between the working conditions is expressed with the distance-coded heat map. Secondly, the Savitzky−Golay (SG) filter is used to smooth the data, which preserves the original char... [more]

Improving the thermal efficiency of truck diesel engines requires comprehensive optimization of the engine, exhaust aftertreatment (EAT), and possible waste heat recovery (WHR). Lower exhaust temperature at mid and low working points has caused difficulty in both emission clarification and heat recovery, which requires thermal management. Based on the diesel engine bench test and separate bench tests, this paper focuses on the thermal management strategy optimization, to increase the exhaust temperature at lower working points and optimize the thermal efficiency of the whole system. The test and numerical analysis showed that as exhaust temperature increased from 200~250 °C to 300~350 °C, soot passive regeneration reactions were enhanced, nitrogen oxide emission decreased, and energy recovery was improved. Moderate throttle valve adjustment coupled with early post injection could effectively achieve the required temperature increase. The optimized thermal management strategy increased... [more]

Chemical flooding is important and effective enhanced oil recovery processes are applied to improve the recovery of heavy oil reservoirs. Emulsification occurs during chemical flooding processes, forming an oil-in-water (O/W) emulsion system. In this work, the heavy oil emulsion system is characterized as a three-phase (continuous oil phase, dispersed oil phase, and continuous water phase) system. Based on a capillary tube model, a new relative permeability model is proposed to describe the flow of the emulsion system in porous media quantitatively, considering the physicochemical properties of emulsions and the properties of porous media. A resistance factor is derived in this model to describe the additional resistance to the emulsion flow caused by the interaction between dispersed oil droplets and the pore system. Three dimensionless numbers related to the emulsion porous flow process were proposed and their different effects on the three-phase relative permeability are investigate... [more]

Three-cylinder gasoline engines are increasingly favored by major automobile manufacturers due to their good fuel economy, low manufacturing cost and low fuel consumption. However, the inherent balance problem has an adverse effect on the vibration of the whole engine and even the comfort of the whole vehicle, which limits its application in high-end models. This paper studied the dynamics characteristic of the flexible multi-body system of the three-cylinder gasoline engine crankshaft. A dynamic simulation model of the flexible multi-body system of the three-cylinder gasoline engine crankshaft is established through the flexible treatment of the engine crankshaft. The kinematics and dynamics characteristics of each component of the crankshaft connecting rod system are obtained by analyzing the kinematics and dynamics characteristics of the engine shafting system. The relevant factors affecting the vibration of the engine crankshaft system are studied through the establishment of the a... [more]

Cogeneration, also known as a combined heat and power (CHP) system, produces both power and heat simultaneously. It reduces the operating costs and emissions by utilising waste heat from steam turbines and contributes to incapacitating the intermittency of renewable energy. The CHP-economic dispatch (CHP-ED) is needed to overcome the load dynamics as well as renewable intermittency. In this work, a CHP system connected with a wind power plant is considered for analysing the CHPED within a typical power system area. This study examines, the CHPED with and without a wind integrated energy network. The main objective of this work is to minimise the total operating cost, while meeting the generators’ constraints and prioritising the wind power output. The feasible operating region, valve point loading impact, and prohibited working regions of the CHP plants are taken while finding a CHPED solution with an integrated wind turbine. To find a CHPED solution, an optimisation algorithm was appl... [more]

Mudstone is a widely occurring type of rock in deep mining, and it is crucial to understand its failure mechanisms and strength characteristics under the interaction of water and high stress to ensure the stability of deeply buried engineered mudstone. In this study, the composition and the structure of mudstone were obtained, and triaxial tests were conducted on mudstone under five different water contents and four different confining pressures using a triaxial servo press. The variation rules for the peak strength and residual strength were obtained, and the applicability of the strength criteria was analyzed through fitting. The results showed that both the peak strength and the residual strength decreased linearly with increasing water content, with the peak strength decreasing more rapidly. Both the peak strength and the residual strength increased with increasing confining pressure, with the residual strength increasing more rapidly. The decrease in strength was primarily due to... [more]

A significant effort is required to reduce China’s dependency on fossil fuels while also supporting worldwide efforts to reduce climate change and develop hydrogen energy systems. A hydrogen economy must include renewable energy sources (RESs), which can offer a clean and sustainable energy source for producing hydrogen. This study uses an integrated fuzzy AHP−fuzzy TOPSIS method to evaluate and rank renewable energy sources for developing a hydrogen economy in China. This is a novel approach because it can capture the uncertainty and vagueness in the decision-making process and provide a comprehensive and robust evaluation of the alternatives. Moreover, it considers multiple criteria and sub-criteria that reflect the environmental, economic, technical, social, and political aspects of RESs from the perspective of a hydrogen economy. This study identified five major criteria, fifteen sub-criteria, and six RES alternatives for hydrogen production. This integrated approach uses fuzzy AHP... [more]

Model compounds were used to provide some chemical boundaries for the eight-fraction SAR-ADTM characterization method for heavy oils. It was found that the Saturates fraction consists of linear and highly cyclic alkanes; the Aro-1 fraction consists of molecules with a single aromatic ring; the Aro-2 fraction consists of mostly 2 and 3-ring fused aromatic molecules, the pericondensed 4-ring molecule pyrene, and molecules with 3−5 rings that are not fused; and the Aro-3 fraction consists of 4-membered linear and catacondensed aromatics, larger pericondensed aromatics, and large polycyclic aromatic hydrocarbons. The Resins fraction consists of mostly fused aromatic ring systems containing polar functional groups and metallated polar vanadium oxide porphyrin compounds, and the Asphaltene fraction consists of both island- and archipelago-type structures with a broad range of molecular weight variation, aromaticity, and heteroatom contents. The behavior of the eight SAR-ADTM fractions during... [more]

To solve the problem of deposits formation in the exhaust pipe of a diesel engine SCR (selective catalytic reduction) system, the CFD (computational fluid dynamics) model of the exhaust pipe was established to research the influence of structural parameters on the wall film from the perspective of optimizing the flow field. The solid structure was simplified in the modeling without considering the flow fields inside the catalytic converter. The simulation conditions were obtained through bench tests and vehicle real road tests. The spray and temperature simulation results were verified via high-speed photographic and bench tests under three typical operating conditions. The conclusions are as follows: compared to the case with a step surface, wall film mass was reduced by 48.27~55.4% when the exhaust pipe had no step surface; compared to the case where the nozzle orifices were located 10 mm off center axis, wall film mass reduced by 2.83~6.38% when the nozzle orifices located in the ce... [more]

The pressing problems of water scarcity in many parts of the planet make water desalination one of the technological solutions for guaranteeing the fresh water supply. However, desalination processes require high energy consumption, mainly provided by fossil fuels. The integration of renewable energy sources into desalination processes is a promising option for decarbonizing the desalination sector. As most water-scarce regions with access to seawater frequently have high solar irradiation levels, it seems appropriate to exploit the sun to power the desalination process. This work presents the assessment of two integrated solar power and desalination systems regarding efficiency and water production. Two desalination processes (multi-effect distillation and reverse osmosis) are studied for potential coupling with the combined cycle of a central receiver solar plant to produce electricity and freshwater. In the case of the multi-effect distillation plant, it is integrated by replacing t... [more]

Our world still greatly relies on the combustion process to convert fuel into power and heat for purposes such as gas turbines, internal combustion (IC) engines, jet engines, rockets, boilers, and furnaces [...]

Conventional wastewater treatment plants (CWTPs) are intensive energy consumers. New technologies are emerging for wastewater treatment such as microbial electrolysis cells (MECs) that can simultaneously treat wastewater and generate hydrogen as a renewable energy source. Mathematical modeling of single and dual-chamber microbial electrolysis cells (SMEC and DMEC) has been developed based on microbial population growth in this study. The model outputs were validated successfully with previous works, and are then used for comparisons between the SMEC and DMEC regarding the hydrogen production rate (HPR). The results reveal that the daily HPR in DMEC is higher than in SMEC, with about 0.86 l H2 and 0.52 l H2, respectively, per 1 L of wastewater. Moreover, the results have been used to compare the HPR in water electrolysis (WE) processes and MECs. WE consume 51 kWh to generate 1 kg of hydrogen, while SMEC and DMEC require only 30 kWh and 24.5 kWh, respectively.

This paper proposes a model for determining deformation in the upper 50% of an ice borehole. Based on this model, the borehole deformation of DK-1 at Dome A was studied. Furthermore, the effects of surface temperature, temperature gradient, surface snow density, and drilling fluid density on borehole deformation were investigated. The results showed that borehole shrinking, expansion, and mixed existence occurred simultaneously in DK-1. Borehole deformation increased with increasing surface temperature, while temperature gradient had a minimal effect. Borehole deformation also increased with increasing surface snow density and decreasing drilling fluid density when the borehole shrank; however, the situation was reversed when the borehole expanded. The influence of ice temperature was dominant in deformation. However, when depth exceeded 1200 m, the sensitivity of ice borehole deformation in the direction of the minimum principal stress increased with an increase in drilling fluid dens... [more]

The separation of immiscible liquids is critical in many industrial processes, such as water treatment, different extraction processes, the petroleum industry, food production, and medicine. This work provides an overview of present research on the separation of liquid mixtures. A brief summary of the thermodynamic basis is provided, covering phase equilibrium, phase diagrams, and thermodynamic properties of phases. Additionally, the fundamentals of dispersion, necessary for discussing liquid−liquid separation, are presented. Subsequently, different liquid−liquid separation methods are discussed, highlighting their advantages and limitations. These methods include decanters, coalescers, centrifugal separators, membranes and electro-coalescers for liquid−liquid separation. Phase properties, dispersion formation, and time and space constraints specify the most efficient separation method. Phase recycling is also briefly discussed as a method to reduce the environmental impact of liquid−l... [more]

Improving the accuracy of PV power prediction is conducive to PV participation in economic dispatch and power market transactions in the distribution network, as well as safe dispatch and operation of the grid. Considering that the selection of highly correlated historical data can improve the accuracy of PV power prediction, this study proposes an integrated PV power prediction method based on a multi-resolution similarity consideration that considers both trend similarity and detail similarity. Firstly, using irradiance as the similarity variable, similar-days were selected using grey correlation analysis to form a set of similar data to control the similarity, with the overall trend of the day to be predicted at a macro level. Using irradiance to calculate the similarity at each specific point in time via Euclidean distance, similar-times were identified to form another set of similar data to consider the degree of similarity in detail. The above approach enables the selection of si... [more]

Although desalinations with renewables were introduced some time ago, conventional desalination units are still applied. Conventional desalinations account for 90% of desalinations worldwide. Yet, they have two significant issues: a high demand for energy and a high level of environmental contaminants. Such issues are studied and remedies are suggested in the current study. Varieties of biofuel blends in dual and ternary bases are investigated experimentally for indirect desalination. Results showed that ternary blends can introduce lower desalination potentials than fossil fuels by about 4−7%. The best ternary blends for the indirect desalination process are iBE, followed by niB, and finally EM. The EGT of iBE is greater than niB and EM by about 1.1 and 1.2%, respectively. Both n-butanol/iso-butanol−gasoline dual blends introduced an almost similar desalination potential as the ternary blends (e.g., lower desalination by about 4.4 and 4.7%). Nevertheless, bio-ethanol/bio-methanol−gaso... [more]

Problems such as well loss and collapses in deep shale gas drilling are most often due to the development of cracks in the shale formation, resulting in significant leaks of drilling fluid, the sticking and burrowing of drilling tools, and other engineering accidents. In addition, the horizontal sections of wells are very long and issues of friction, rock transport, and formation contamination loom large. As a result, the performance of drilling fluids directly affects drilling efficiency, engineering accident rates, and reservoir protection effects. We first analyze the mechanisms of each emulsifier in an oil-based drilling fluid formulation and the filtration reduction mechanisms, taking into account the collapse-prone and abnormally high-pressure characteristics of shale formations. We undertake an experimental evaluation and optimization of polymeric surfactants, such as primary and secondary emulsions for high-performance oil-based drilling fluids. The design of rigid and deformab... [more]