In this study, the water absorption, mechanical properties, and energy evolution characteristics of sandstone were examined through experimental and theoretical analysis. The P-wave velocity was found to initially decrease, then increased with immersion time and water content. The water absorption rates of three sandstone specimens decreased with immersion time and water content. The post-peak deformation of the sandstone changed from brittle failure to strain softening. With the increase in water content, the peak strength and loading Young’s modulus per cycle decreased. The loading Young’s modulus showed that the unloading stress and increment of unloading stress nonlinearly increased with the number of cycles and decreased before peak strength. With the increase in the number of cycles, residual strains of the sandstone specimens decreased slightly initially and then increased, while the elastic strains increased before peak strength and then decreased at the post-peak stage. With t... [more]

In this study, we assessed the unconventional reservoir characteristics of the Lower Turonian carbonates from the southeastern Constantine Basin. We integrated petrography, petrophysical, and rock-mechanical assessments to infer formation properties and unconventional reservoir development strategies. The studied fossiliferous argillaceous limestones are rich in planktonic foraminifera, deposited in a calm and low energy depositional condition, i.e., deep marine basinal environment. Routine core analysis exhibits very poor porosity (mostly < 5%) and permeability ( 0.48) and fracability (FI > 0.5) indices compared to the lower interval. Borehole breakouts indicate ~N-S SHmax orientation and a normal to strike-slip transitional stress state has been constrained based on a geomechanical assessment. We analyzed safe wellbore trajectory and minimum mud weight requirements to ensure stability in the deviated and horizontal wells required for field development. At the present stress state,... [more]

Half Heusler materials are promising thermoelectric materials with potential application in generators at medium range temperatures. Solid solutions are typically prepared by arc melting, presenting interesting properties. In this work, the effect of Hf incorporation and the formation of solid solutions is discussed. More specifically, Ti1−xHfxNiSn and (Ti0.4Zr0.6)1−yHfyNiSn half Heusler materials were synthesized via mechanical alloying and consolidated via hot press sintering. Hf incorportation in the lattice strongly affected the lattice thermal conductivity due to the large mass fluctuation. The power factor and thermoelectric figure of merit was optimized via Sb doping the values of 34 μW/cmK2 and 38 μW/cmK2; 0.72 and 0.76 at 762 K for Ti0.4Hf0.6NiSn0.985Sb0.015 and (Ti0.4Zr0.6)0.7Hf0.3NiSn0.98Sb0.02, respectively, were reached.

Most old oil and gas fields worldwide are depleted, making drilling in these sedimentary zones extremely difficult, especially in complex pore pressure regimes when they are accompanied by over-pressure zones. Considering that typical wellbore stability studies provide a conservative mud density curve to prevent wellbore failure, dynamic geomechanical approaches are required to provide more flexible and manageable drilling in such complex cases in order to address anticipated drilling obstacles. This study aims to apply the more dynamic concept, known as “depth of damage” (DOD), in the El Morgan oil field, Gulf of Suez Basin, to deliver a more optional mud density window that helps in the safe drilling of different pore pressure regimes within the area, as well as the implications of applying this drilling strategy in the studied basin. In this paper, well logging and downhole measurements were used to develop a 1D geomechanical earth model and infer the in situ stresses in the studied... [more]

In this paper, based on the study of hydrogen accumulation in the electrodes of nickel−cadmium batteries, a high-capacity hydrogen storage system (HSS) is proposed. It has been experimentally proven that hydrogen accumulates in the electrodes of nickel−cadmium batteries in large quantities over the course of their operation. It has been shown that hydrogen accumulates in metal−ceramic matrices of sintered oxide−nickel electrodes in the form of metal hydrides. The gravimetric capacity of the nickel matrix is 20.3 wt% and the volumetric capacity is 406 kg m−3. The obtained gravimetric capacities for metal−ceramic matrices exceed almost four times the criteria for onboard hydrogen storage systems established by the US Department of Energy (DOE), as well as previously obtained results for any reversible hydrogen accumulation materials. In addition, in our previous papers, it was proved that if we use thermal runaway for the desorption of hydrogen from metal hydrides then the kinetic and th... [more]

High-temperature superconducting materials have shown great potential for the design of large-scale industry applications. However, they are complicated under AC conditions, resulting in penalties such as power loss or AC loss. This loss has to be considered in order to design reliable and efficient superconducting devices. Furthermore, when superconductors are used in rotating machines, they may be exposed to rotating magnetic fields, which is critical for the design of such machines. Existing AC loss measuring techniques are limited to measuring under one-dimensional AC magnetic fields or transport currents. Therefore, it is essential to develop and investigate robust experimental techniques to investigate the loss mechanism in HTS machines. In this paper, a new and novel experimental technique has been presented to measure AC loss in rotating magnetic field conditions. The loss under rotating magnetic fields is measured and compared by numerical modeling methods, and the results sho... [more]

Although it is well known that the magnetic properties of electrical steel can be deeply affected by the cutting process, it is still not clear how to accurately evaluate these effects on a prototyped machine on its final shape, especially at a high frequency or a high power rating. This research provides a more practical method for accurate measurement of magnetic losses in electrical steel with consideration of material degradation effects due to the cutting process. Unlike other similar studies, these investigations are conducted not only on a few laminations but also on a complete electrical machine core. For a fair comparison between both cases, backlack bonding is used for lamination stacking since it is the most non-damaging joining technique. Two different test setups are used to measure the steel performance at a wide range of frequency and input power. Furthermore, a full axial length stator of a switched reluctance machine (SRM) is used as a case study to identify the magnet... [more]

Straw bale building construction is attracting a revived public interest because of its potential for reduced carbon footprint, hygrothermal comfort, and energy savings at an affordable price. The present paper aims to summarize the current knowledge on straw bale construction, using available data from academic, industry, and public agencies sources. The main findings on straw fibers, bales, walls, and buildings are presented. The literature shows a wide variability of results, which reflects the diversity of straw material and of straw construction techniques. It is found that the effective thermal conductivity, density, specific heat, and elastic modulus of straw bales used in construction are in the range 0.033−0.19 W/(m·K), 80−150 kg/m3, 1075−2000 J/(kg·K), and 150−350 kPa respectively. Most straw-based multilayered walls comply with fire resistance regulations, and their U-value and sound reduction index range from 0.11 to 0.28 W/m2 K and 42 to 53 dB respectively, depending on th... [more]

Most cathode materials for Li-ion batteries exhibit a low electronic conductivity. Therefore, a considerable amount of conductive additives is added during electrode production. A mixed phase of carbon and binder provides a 3D network for electron transport and at the same time improves the mechanical stability of the electrodes. However, this so-called carbon binder domain (CBD) hinders the transport of lithium ions through the electrolyte and reduces the specific energy of the cells. Therefore, the CBD content is an important design parameter for optimal battery performance. In the present study, stochastic 3D microstructure modeling, microstructure characterization, conductivity simulations as well as microstructure-resolved electrochemical simulations are performed to identify the influence of the CBD content and its spatial distribution on electrode performance. The electrochemical simulations on virtual, but realistic, electrode microstructures with different active material cont... [more]

One of the key areas of the UN’s sustainable development goals is growing affordable and clean energy. Utilizing solar energy that is now accessible will significantly lessen the demand for fossil fuels. Around the world, cooking is a crucial activity for homes and uses a lot of non-renewable energy. Uncontrolled firewood usage results in deforestation, whereas using biomass-related fuels in inefficient stoves can result in smoke emanating from the kitchen and associated health issues. The benefits of solar cooking include reducing smoke-related problems and saving on fossil fuels and firewood. Applying thermal storage systems in cooking helps households have all-day cooking. This review article presents the research and development of a solar cooking system that transfers solar energy into the kitchen and integrates with the thermal energy storage system, finding the factors affecting indoor solar cooking performance. Adding portable cooking utensils helps in improved solar indoor coo... [more]

A systematic study of the influence of synthesis conditions on the structural, morphological, and electrical properties, as well as the electrochemical performance of hemp fiber-derived carbon materials was performed. An analysis of the capacitive response of carbons obtained under various activation conditions with additional treatment with HNO3 and annealing was completed. The contribution of the formation of an electrical double layer at the outer electrode−electrolyte interface, as well as on surfaces inside micropores, has been studied and analyzed in terms of the effect of the turbostratic carbon properties (average lateral size of graphite crystallites, pore size distribution, BET surface area).

Thermal management of electronic components is critical for long-term reliability and continuous operation, as the over-heating of electronic equipment leads to decrement in performance. The novelty of the current experimental study is to investigate the passive cooling of electronic equipment, by using nano-enriched phase change material (NEPCM) with copper foam having porosity of 97%. The phase change material of PT-58 was used with graphene nanoplatelets (GNPs) and magnesium oxide (MgO) nanoparticles (NPs), having concentrations of 0.01 wt.% and 0.02 wt.%. Three power levels of 8 W, 16 W, and 24 W, with corresponding heating inputs of 0.77 kW/m2, 1.54 kW/m2 and 2.3 kW/m2, respectively, were used to simulate the heating input to heat sink for thermal characterization. According to results, at 0.77 kW/m2 heating input the maximum base temperature declined by 13.03% in 0.02 wt.% GNPs-NEPCM/copper foam case. At heating input of 1.54 kW/m2, the maximum base temperature reduction of 16% w... [more]

Integrating a solar water heater (SWH) with a phase change material (PCM)-based latent heat storage is an attractive method for transferring load from peak to off-peak hours. This transferring load varies as the physical parameters of the PCM change. Thus, the aim of this study is to perform a parametric analysis of the SWH on the basis of the PCM’s thermophysical properties. A mathematical model was established, and a computation code was developed to describe the physical phenomenon of heat storage/release in/from the SWH system. The thermal energy stored and the energy efficiency are used as key performance indicators of the new SWH−PCM system. The obtained numerical results demonstrate that the used key performance indicators were significantly impacted by the PCM thermo-physical properties (melting temperature, density, and latent heat). Using this model, various numerical simulations are performed, and the results indicate that, SWH with PCM, 20.2% of thermal energy on-peak perio... [more]

Hydraulic fracturing is an important technology for the stimulation of oil and gas reservoirs. Conventional fracturing technology based on “sand-carrying” faces some challenges such as sand plugs; incompatibility with the well completion method; damage to the reservoir caused by the incomplete gel-breaking of the fracturing fluid; solid proppants inefficiently turning the corner in complex fracture networks, and so on. In this paper, a novel self-generated proppant fracturing fluid system is proposed to solve the above problems caused by “sand-carrying”. The advantage of the fracturing fluid system is that in the whole process of fracturing, no solid proppants will be injected. The fracturing fluid itself will transform into solid proppants in the induced fractures under high temperatures to resist fracture closure stress. The fluid system consists of two kinds of liquids. One is the phase change liquid (PCL), which occurs as a liquid−solid phase change at high-formation temperatures t... [more]

Existing building carbon emissions contribute to global climate change significantly. Various Green Building Rating Systems (GBRS) have considered low-carbon requirements to regulate the emissions. Low-carbon retrofitting is an important way to reduce existing building CO2 emissions. However, low-carbon retrofitting of existing public buildings is not sufficient and systematic, and there is a lack of research on low-carbon retrofitting from the perspective of GBRS. The purpose of this study is to propose a carbon emission control framework for existing public buildings based on GBRS analysis and guide the low-carbon retrofitting. This study makes comparisons among the Leadership in Energy and Environmental Design (LEED), Building Research Establishment Environmental Assessment Method (BREEAM), Green Mark (GM), and Assessment Standard for Green Retrofitting of Existing Buildings (ASGREB). A low-carbon retrofit pathway for existing public buildings is proposed from the GBRS research for... [more]

An experimental study was carried out on the ignition characteristics of the HAN/(Emim)(EtSO4) (hydroxylammonium nitrate and 1-ethyl-3-methyl-imidazolium ethyl sulfate) dual-mode ionic liquid monopropellant in chemical propulsion mode in model thrusters. Firstly, a model thruster with a detachable convergent nozzle was designed and fabricated. Secondly, catalytic ignition experiments at different flow rates were carried out in atmosphere and in high chamber pressure environment, respectively, using a model thruster, with and without the convergent nozzle. During the catalytic ignition process, measurement methods such as thermocouple, pressure sensor, and flue gas analyzer were employed to obtain the temperature at different depths of the catalytic bed, the pressure of the combustion chamber, and the concentration variations of gaseous products CO, CO2, CH4, SO2, NO, and NO2. Then the three characteristic stages of water evaporation, HAN decomposition, and (Emim)(EtSO4) combustion were... [more]

Changes observed in the Polish energy sector, including the demand for and use of heat, require the introduction of appropriate measures aimed at diversifying the available heat sources, increasing the share of renewable and low-emission sources in heat production, and increasing waste heat recovery and its usage. There is an increasing emphasis on issues such as reducing the carbon footprint, reducing pollution, reducing the use of raw materials, reducing waste heat, and improving the energy efficiency of businesses. Increasingly, the question arises—what technologies can be used as an answer to the identified problems and needs. The solution proposed in this publication to support these needs is the use of mobilized thermal energy storage (M-TES) technology. The use of this technology has great potential, but also involves a number of conditions that need to be taken into account when undertaking the design, construction, and use of this type of technology. The primary purpose of thi... [more]

Performed gels are widely used in fields to support profile modification and Enhance Oil Recovery. Previous studies of profile modification of performed gels mainly used the index of pressure, resistance factor, or residual resistance factor to represent their ability. However, there is a lack of methods available to directly study their modification ability. In this article, the preformed gels with fluorescence properties, CQDs@PPG, would provide a new way to explore the profile modification of preformed gels. This paper uses poly (acrylamide, sodium p-styrene sulfonate), carbon quantum dots, and N,N-methylenebisacrylamide to prepare the CQDs@PPG via inverse emulsion polymerization. The morphology, size distribution, structure, fluorescence characteristics, surface potential thermal stability, viscosity changes, and viscoelastic properties of CQDs@PPG were analyzed. Moreover, the fluorescence properties of CQDs@PPG under different temperature, salinity, and pH were examined. Results i... [more]

Transparent conducting materials (TCMs) are essential components for a variety of optoelectronic devices, such as photovoltaics, displays and touch screens. In recent years, extensive efforts have been made to develop TCMs with both high electrical conductivity and optical transmittance. Based on material types, they can be mainly categorized into the following classes: metal oxides, metal nanowire networks, carbon-material-based TCMs (graphene and carbon nanotube networks) and conjugated conductive polymers (PEDOT:PSS). This review will discuss the fundamental electrical and optical properties, typical fabrication methods and the applications in solar cells for each class of TCMs and highlight the current challenges and potential future research directions.

Due to the recent surge in silicon demand for solar modules, thin-film photovoltaic (PV) modules have a potential to penetrate the market in significant numbers. As an alternate candidate, thin film technologies in PVs have the ability to achieve better performance. The competing thin-film PV technologies have the flexibility to adapt to any sort of curvature compared to rigid solar cells (SCs). Due to the peculiar characteristics of newer solar materials, stability issues, reflection losses, advancements in electrode materials and dopant materials with a photoactive layer are current challenges driving the industrial-academic voyage of development of solar materials for the betterment of Photo-conversion Efficiency (PCE). Based on the photoactive materials used over time, SC evolution was broadly classified into first, second and third generation SCs. In this review, the basic working mechanisms, various materials used, drawbacks and stability issues of different SCs are discussed ext... [more]

It is extremely dangerous for a turbocharged boiler to have a leakage fault in its vaporization tube. However, early detection and fault diagnosis of micro-leakage faults are very difficult. On the one hand, there are few fault samples that lead to a difficult and intelligent diagnosis. On the other hand, the system fault response characteristics of the characterization parameters in the process are complex and easily confused with the load-changing characteristics. In order to obtain fault samples and identify fault characteristics, a fault simulation model for the micro-leakage of the boiler evaporation tube is established based on the dynamic mathematical model of all working conditions. The model’s effectiveness is verified by typical fault experiments. The dynamic simulation experiments of three kinds of micro-leakage and four kinds of load changing were carried out. Through the analysis of combustion equilibrium and vapor-liquid equilibrium of 14 groups of characterization parame... [more]

The performance of sodium-ion batteries largely depends on the presence and properties of passive films formed on the electrode/electrolyte interfaces. Passive films on negative electrodes inevitably result from the reduction in electrolyte components (solvent and salt anion). They have the properties of a solid electrolyte with sodium ion conductivity and are insulators in terms of electronic conductivity. Usually, they are called SEI—solid electrolyte interphase. The formation of SEI is associated with the consumption of a certain charge, which is an irreversible capacity. Passive films on the surface of positive electrodes (CEI—cathode electrolyte interphase) arise as a result of electrolyte oxidation. The present review summarizes the literature of the recent 15 years concerning the effects of electrode nature (hard carbon, other carbon materials, various metals, oxides, chalcogenides, etc.), electrolyte composition, and other factors on composition and properties of SEIs in sodium... [more]

The catalytic conversion of lignin model compounds was performed using Ru/C catalysts and an autoclave reactor. The Ru/C catalysts were prepared by the impregnation method using highly porous homemade activated carbon and characterized by XRD, SEM, and specific surface area. The catalytic reactions were performed in a high pressure/temperature reactor at different temperatures and with different solvents. The results showed that the novel Ru/C catalysts prepared from carbon supports activated by the KOH agent showed higher catalytic activity than the commercial catalyst. Ethanol and 2-propanol were suitable solvents for the cleavage of the β−O−4 ether bond of 2-phenoxy-1-phenyl ethanol (~65−70% conversion) over a Ru/C-KOH-2 catalyst at 220 °C in comparison to tert-butanol and 1-propanol solvents (~43−47% conversion of 2-phenoxy-1-phenyl ethanol). Also, the increase in reaction temperature from 200 °C to 240 °C enhanced the cleavage of the ether bond with an increase in phenol selectivi... [more]

Due to increased energy demand, it is vital to enhance the recovery from existing oilfields. Polymer flooding is the most frequently used chemical enhanced oil recovery (cEOR) method in field applications that increases the oil sweep and displacement efficiencies. In recent years, there has been growing interest to assess the use of polymer flooding in an increasing number of field applications. This is due to the improved properties of polymers at high-salinity and high-temperature conditions and an increased understanding of the transport mechanisms of water-soluble polymers in porous media. In this review, we present an overview of the latest research into the application of polymers for cEOR, including mechanisms of oil recovery improvement and transport mechanisms in porous media. We focus on the recent advances that have been made to develop polymers that are suitable for high-salinity and high-temperature conditions and shed light on new insights into the flow of water-soluble p... [more]

Thermal energy storage (TES) is the most suitable solution found to improve the concentrating solar power (CSP) plant’s dispatchability. Molten salts used as sensible heat storage (SHS) are the most widespread TES medium. However, novel and promising TES materials can be implemented into CSP plants within different configurations, minimizing the TES costs and increasing the working temperature to improve the thermal performance of the associated power block. The first objective of this review is to provide an overview of the most widespread CSP technologies, TES technologies and TES-CSP configurations within the currently operational facilities. Once this information has been compiled, the second aim is to collect and present the existing European and North American TES-CSP Research and Development (R&D) projects within the last decade (2011−2021). Data related to these projects such as TES-CSP configuration path, TES and CSP technologies applied, storage capacity, power block associat... [more]