Building cooling and heating, solar-powered energy production, energy recovery, and other energy-consuming industries have all seen an increase in the use of cold/hot latent thermal energy storage (LH-TES). Through energy recovery, LH-TES that uses phase-change materials (PCMs) as a storage medium helps to close the energy supply and demand gap and raises the possibility of energy savings. However, the stability, thermal, physical, and chemical properties of the PCM play a major role in how effectively it can be used. In recent years, adding gelling and thickening agents (GTAs) has gained popularity apart from the nanoparticles (NPs) and nucleating triggers (NTs), particularly for the creation of stable PCMs. Therefore, the current work’s goal is to provide an overview of how GTAs are used in the process of developing reliable PCMs for TES applications. It has been found that using GTAs not only increased stability but also decreased sedimentation, leakage, and the supercooling degree... [more]

A BiF3 powder sample was prepared from the purchased Bi2O3 powder via the precipitation route. The photocatalytic performance of the prepared BiF3 powder was compared with the Bi2O3 powder and recognized as superior. The prepared BiF3 powder sample was added in a plaster of Paris (POP) matrix in the proportion of 0%, 1%, 5%, and 10% by wt% to form POP−BiF3(0%), POP−BiF3(1%), POP−BiF3(5%), and POP−BiF3(10%) composite pellets, respectively, and activated the photocatalytic property under the UV−light irradiation,in the POP. In this work, Resazurin (Rz) ink was utilized as an indicator to examine the photocatalytic activity and self-cleaning performance of POP−BiF3(0%), POP−BiF3(1%), POP−BiF3(5%), and POP−BiF3(10%) composite pellets. In addition to the digital photographic method, the UV−visible absorption technique was adopted to quantify the rate of the de-colorization of the Rz ink, which is a direct measure of comparative photocatalytic performance of samples.

This paper contains a comprehensive study regarding the synthesis and physicochemical properties of new hexasubstitued benzene derivatives. In this work, three compounds of this type (including two electropolymerisable monomers) were synthesized in a one-step reaction with good yields ranging from 34% to 56%. A thermal investigation shows that this type of compound is stable up to 360 °C (10% weight loss temperature). The influence of the substituents in the first and second position of the central benzene on the stability, luminescence, and (spectro)electrochemical behavior was thoroughly studied with the aid of theoretical calculations. In each case, strong blue shifting of the π-π* transition (according to 1,4-disubstitued analogs) was observed, proving this moieties’ orthogonal orientation. In the case of derivatives with a Bt-core-Bt formula (where Bt = 2,2′-bithiophene-5-yl), an electrochemical oxidation process transformed them into conducting polymers. The polymer presents extr... [more]

The research on pore structure and heterogeneity of shale reservoirs has always been a hotspot in the study of unconventional reservoir characteristics. China is a country dominated by continental shale. Compared with marine shale, continental shale has lower maturity and stronger reservoir heterogeneity. In this study, Sha-4 shale in the Liaohe Western Depression was selected for low-temperature nitrogen adsorption, scanning electron microscopy and other experiments revealing the pore structure and fractal characteristics of continental low mature organic-rich shale. The fractal dimension was calculated by the FHH model and the effects of TOC and mineral composition on pore structure and fractal characteristics were discussed. The results show that the Sha-4 shale in the study area is mainly mesoporous and the main pore types are inorganic pores with relatively large pore diameters, such as intergranular pores and inter-crystalline pores. The pore morphology is very complex, mainly na... [more]

Low field pulse nuclear magnetic resonance (LF-NMR) was used to analyze the effects of a polymeric ion retarder and the amount of acryloxyethyl trimethylammonium chloride (DMC) in the retarder on the distribution of T2, thickening property, and strength of cement paste. The effect of pressure and temperature on the thickening curve was investigated, and the hydration products were analyzed using XRD. The result shows that the wrapped water of the precipitation is the main reaction aqueous phase of cement slurry in the hydration, with short T2 time and a large relaxation peak area. The retarder weakens the van der Waals force and electrostatic adsorption force between the water and cement particles, reducing the hydration rate of cement particles. An appropriate increase in the cationic content of polymeric ion retarder can improve the early strength of cement slurry.

Large quantities of gas resources have been found in the Paleo-Mesozoic carbonate rocks in the Sichuan Basin. However, many wells cannot obtain high production in deep low porosity-permeability reservoirs. For this contribution, we provide a steerable pyramid method for identifying the fault damage zone in the Kaijiang−Liangping platform margin, which is infeasible by conventional seismic methods. The results show that steerable pyramid processing could enhance the seismic fault imaging and a series of NW-trending strike-slip faults are found along the trend of the carbonate platform margin. The steerable pyramid attribute presents distinct vertical and horizontal boundaries of the fault damage zone, and heterogeneous intensity of an un-through-going damage zone. The width of the fault damage zone is generally varied in the range of 100−500 m, and could be increased to more than 1000 m in the fault overlap zone, intersection area, and fault tips. Further, the fault damage zone plays a... [more]

Liquid dielectrics are different from each other, but are used to perform the same tasks in high-voltage electrical equipment, especially transformers. In similar conditions, the insulation performance of transformer oils under different types of voltage will provide dielectric resistance. In this study, three different dielectric liquids applied in transformers, namely mineral oil, natural ester and synthetic ester, were tested. Tests under AC and negative DC voltage were performed at electrode gaps of 2.5 mm, 2 mm and 1 mm using disk and VDE type electrodes as per ASTM D1816-84A and ASTM D877-87 standards, respectively. In turn, the impulse voltage tests were performed under an electrode configuration suggested by the IEC 60897 standard. The current data of 500 ms prior to breakdown under AC electrical field stress was decomposed using the empirical mode decomposition (EMD) and variational mode decomposition (VMD) methods. These analyses were conducted before the full electrical brea... [more]

Aiming at obtaining the application characteristics of more nanofluidic stuffing to enrich the database of nanofluidic packer rubber, three zeolite-based nanofluidic types of stuffing with water, glycerin, and a saturated aqueous solution of KCl (hereinafter referred to as saturated KCl solution) as the functional liquids were studied using experiments. The results showed that all the three zeolite-based nanofluidic stuffing types could be applied as stuffing for nanofluidic packer rubber. The setting pressure ranges for zeolite/water, zeolite/glycerin, and zeolite/saturated KCl solution stuffing were 21.71 to 30.62 MPa, 15.31 to 23.57 MPa, and 27.50 to 38.83 MPa, and the specific deformation quantities of the three stuffing types were 72.76, 102.07, and 77.54 mm3∙g−1, respectively. In zeolite/saturated KCl solution stuffing, the number of liquid molecules retained in the nanochannels was the minimum; thus, this stuffing type was the most stable during application. The order of the equ... [more]

In order to study the effect of device structures and silicon wafer positions on light-induced degradation (LID) and regeneration, five groups of industrial PERC and Al-BSF solar cells were fabricated by using silicon wafers from different positions of a B-doped Czochralski silicon (Cz-Si) ingot. Then, the cells were subjected to a dark annealing (200 °C, 30 min), the first LID (45 °C, 1 sun, 12 h), an electrical injection regeneration (175 °C, 18 A, 30 min) and the second LID (45 °C, 1 sun, 12 h) in order, and the variations of performance of the cells with processing time were measured. It was found that after the electrical injection regeneration, the efficiency losses of PERC cells decreased from 1.28−1.76solute in the first LID to 0.09−0.16solute in the second LID, while those of Al-BSF cells decreased from 0.3−0.66solute in the first LID to 0 in the second LID. The efficiency losses of PERC cells during the first LID were caused by the co-action of B-O-defect-induced LID (BO-LID)... [more]

Accurate forecast results of medium and long-term wind power quantity can provide an important basis for power distribution plans, energy storage allocation plans and medium and long-term power generation plans after wind power integration. However, there are still some problems such as low forecast accuracy and a low degree of integration for wind power physical processes. In this study, the Multi-step Informer network is proposed to add meteorological parameters to wind power generation forecast and make network interpretable. The Multi-step Informer network uses Informer to obtain the initial training model according to the historical data of wind power generation, introduces the Informer model of wind speed and air pressure training involved in the dynamic pressure model, and compares the historical data of wind power generation to obtain model modification, so as to further improve the forecast accuracy of Multi-step Informer network. The backpropagation process of the pre-trained... [more]

In order to investigate the effect of rock surface roughness on the occurrence state of shale oil, muscovite mica was firstly characterized by performing atomic force microscopy (AFM). Two-dimensional (2D) images and the three-dimensional (3D) structure of the mica surface were obtained. Wettability of the micas was measured according to the sessile drop method using shale oil, collected from a lacustrine shale oil well drilling through the Yanchang Formation, Ordos Basin. Then, the adhesion forces between shale oil and mica surface with a different roughness were finely measured using AFM mounted with the shale oil modified probe tips. The adhesion force curves at the approaching and retract modes were obtained. The results show that the average roughness value of the mica samples was about 1 nm, while the maximum height was up to 4 nm. The contact angle between shale oil and mica ranged from 128.73° to 145.81°, and increased with increasing surface roughness, which can be described b... [more]

Permeability prediction in hydrocarbon production is an important task. The decrease in permeability due to depletion leads to an increase in the time of oil or gas production. Permeability models usually are obtained by various methods, including coreflooding and the field testing of wells. The results of previous studies have shown that permeability has a power-law or exponential dependence on effective pressure; however, the difficulty in predicting permeability is associated with hysteresis, the causes of which remain not fully understood. To model permeability, as well as explain the causes of hysteresis, some authors have used mechanical reservoir models. Studies have shown that these models cannot be applied with small fluctuations in effective pressures in the initial period of hydrocarbon production. In this work, based on the analysis of well test data, we came to the conclusion that in the initial period of production under constant thermobaric conditions, the permeability o... [more]

This paper investigates high-maturity organic matter-rich shales with high clay mineral contents in the Qingshankou Formation, in the Gulong Depression of the Songliao Basin, at a sub-millimeter scale, using a new laminar division method based on XRF data. The influence of laminar structure on reservoir quality is examined using a combination of geochemistry, mineralogy, and pore structures. Explanatory models are established. Three types of laminar units are distinguished in the study area based on differences in pore structure. These are clay mineral laminae (UA), clay mineral-Ostracod laminae (UB), and clay mineral-felsic laminae (UC). UA has illite intergranular pores, micro-fractures, and organic pores, with diameters of 0.5~2 μm. UB primarily contains Ostracod shell margin fractures, pyrite intergranular pores, and chlorite intragranular pores. UC contains albite and illite intergranular pores. Nitrogen adsorption tests show that UA has the highest clay content and the best speci... [more]

Utilizing sintered ore catalysts (SOC), which are used in the sintering industry for NH3-SCR denitration, is a feasible and economical way to reduce NOx emission in sintering flue gas. Therefore, in order to enhance the denitration efficiency of SOC, sintered ore modified by sulfuric acid and sulfated sintered ore catalysts (SSOC-5) were prepared. Kinetic analyses of these two catalysts for denitration were carried out in this study. On the basis of eliminating the influence of internal and external diffusion, the relationship between reactants and reaction rate was studied by a power function kinetic model. This clarified that the adsorption ability of the acid-modified catalyst for reaction gas adsorption was stronger than that of sintered ore catalysts, and the reaction rate was also accelerated. The NO, NH3 and O2 reaction orders of SOC were 1, 0.3 and 0.16 at 250~300 °C, while these values of SSOC-5 were 0.8, 0.06 and 0.09, respectively. The apparent activation energy of SOC was 8... [more]

A two-step process using colloid milling (CM) and hot water (HW) treatment was evaluated for its ability to improve xylose recovery and the enzymatic digestibility of oak wood. In the first step, CM pretreatment was applied at a milling (feeding) speed of 100 mL/min with four different milling times (3, 6, 9, and 12 h), and the enzymatic digestibility and physical properties of each substrate were measured. In the second-step, the HW pretreatment was applied to enhance the enzymatic digestibility and xylan recovery at various reaction severities (Log R0) from 2.07 to 4.43 using 12 h colloid-milled (CM-treated) oak wood. Compared with untreated oak wood, CM not only significantly disrupted the structure of oak wood but also increased its Brunauer−Emmett−Teller surface area (42-fold) and pore volume (28-fold). The crystallinity of two-step-treated oak wood was decreased to 34.8, while the enzymatic digestibility of 12 h CM-treated oak wood was increased to 58.1% at enzyme loading of 30 f... [more]

The behavior of convective boundary conditions is studied to delineate their role in heat and mass relegation in the presence of radiation, chemical reaction, and hydro-magnetic forces in three-dimensional Powell−Eyring nanofluids. Implications concerning non-Fourier’s heat flux and non-Fick’s mass flux with respect to temperature nanoparticle concentration were examined to discuss the graphical attributes of the principal parameters. An efficient optimal homotopy analysis method is used to solve the transformed partial differential equations. Tables and graphs are physically interpreted for significant parameters.

More and more attention is being paid to the solar reflectance of built-up surfaces due to its influence on the summer heating of buildings and urban areas and the consequent effects on energy needs for air conditioning, as well as on the peak load of the electric grid. Several standard test methods are available for measuring solar reflectance in the laboratory or in the field, based on different devices and approaches. A convergence of some methods has been achieved by rating programs in the U.S. and, more recently, in Europe and other areas. However, laboratory or field measurements are impractical for characterizing a large number of urban surfaces—whether it is for identifying critical issues, developing policies, or verifying compliance with building requirements. In this regard, satellite remote sensors have recently become available, through which it is possible to estimate the reflectance of roof and pavement surfaces thanks to a spatial resolution that is suitable for identif... [more]

We study the wave anelasticity (attenuation and velocity dispersion) of a periodic set of three flat porous layers saturated by two immiscible fluids. The fluids are very dissimilar in properties, namely gas, oil, and water, and, at most, three layers are required to study the problem from a general point of view. The sequence behaves as viscoelastic and transversely isotropic (VTI) at wavelengths much longer than the spatial period. Wave propagation causes fluid flow and slow P modes, inducing anelasticity. The fluids are characterized by capillary forces and relative permeabilities, which allow for the existence of two slow modes and the presence of dissipation, respectively. The methodology to study the physics is based on a finite-element uspcaling approach to compute the complex and frequency-dependent stiffnesses of the effective VTI medium. The results of the experiments indicate that there is higher dissipation and anisotropy compared to the widely used model based on an effect... [more]

The manufacturing of thermally stable solar coatings with high photo-thermal performance represents a key factor for the further deployment of the CSP technology. Since 2005, ENEA has been developing solar coatings suitable for medium and high temperature applications based on the technology of double nitride cermet, by employing silver and tungsten as infrared reflectors, respectively. Thanks to the high infrared reflectance of silver, the corresponding coatings have better optical performance than those with tungsten; however, the high diffusivity of silver compromises its use at high temperature. In order to improve the structural and chemical stability at medium and high temperature of coatings based on silver, this infrared reflector was placed between compact and uniform layers of metal and cermet manufactured by using high-energy and fast deposition processes. In particular, an Unbalanced Magnetron cathode was adopted to promote an ion-assisted deposition process that improved u... [more]

This study is related to the heat energy transfer during 3D nanofluid (water-based) motion over a rotating surface by incorporating the combined impacts of thermal radiations and couple stress. The flow is modeled by a set of non-linear coupled PDEs, which is converted to a set of coupled non-linear ODEs by using suitable similarity transformations. The transformed equations are solved with the built-in NDSolve command. The effects of relevant interesting parameters on the nanofluid velocity components and temperature distribution are explained through various graphs. It is found that the velocity component f(η) is increased with higher values of γ and A0 while it drops with an increasing rotation parameter and nanoparticle volume fraction. The fluid temperature increases with higher αnf, Rd, ϵ2, ϵ3, A1 and drops with increasing Pr, ϵ1 and couple stress parameter (A0). The Nusselt number remains constant at a fixed Pr and Rd, whereas it increases with increasin... [more]

The aim of the work was to evaluate the possibility of using commercial and modified activated carbons for the removal of oxytetracycline from aqueous solutions. The kinetics and statics of adsorption as well as the effect of the activated carbon dose and solution pH on the efficiency of the oxytetracycline adsorption were analyzed. Based on the study of oxytetracycline adsorption isotherms, the activated carbons were ranked in the following order: F-300 > WG-12 > Picabiol > ROW08 > WACC 8 × 30 > F-100 > WAZ 0.6−2.4. The most effective activated carbons were characterized by large specific surfaces. The best matching results were obtained for: Redlich−Peterson, Thot and Jovanovic models, and lower for the most frequently used Freundlich and Langmuir models. The adsorption proceeded better from solutions with pH = 6 than with pH = 3 and 10. Two ways of modifying activated carbon were also assessed. A proprietary method of activated carbon modification was proposed. It uses the heating o... [more]

When gas hydrates dissociate into gas and liquid water, many gas bubbles form in the water. The large bubbles disappear after several minutes due to their buoyancy, while a large number of small bubbles (particularly sub-micron-order bubbles known as ultra-fine bubbles (UFBs)) remain in the water for a long time. In our previous studies, we demonstrated that the existence of UFBs is a major factor promoting gas hydrate formation. We then extended our research on this issue to carbon dioxide (CO2) as it forms structure-I hydrates, similar to methane and ethane hydrates explored in previous studies; however, CO2 saturated solutions present severe conditions for the survival of UFBs. The distribution measurements of CO2 UFBs revealed that their average size was larger and number density was smaller than those of other hydrocarbon UFBs. Despite these conditions, the CO2 hydrate formation tests confirmed that CO2 UFBs played important roles in the expression of the promoting effect. The ana... [more]

In this study, magnetic steel slag biochar (MSSB) was synthesized from low-cost steel slag waste to investigate the effectiveness of steel slag biochar composite for NH4-N removal and magnetic properties in aqueous solution. The maximum adsorption capacity of NH4-N by MSSB was 4.366 mg/g according to the Langmuir model. The magnetic properties of MSSB indicated paramagnetic behavior and a saturation magnetic moment of 2.30 emu/g at 2 Tesla. The NH4-N adsorption process was well characterized by the pseudo-second order kinetic model and Temkin isotherm model. This study demonstrated the potential of magnetic biochar synthesized from steel slag waste for NH4-N removal in aqueous solution.

This paper reports the results of a study concerned with air−water and air−oil two-phase flow in channels packed with open-cell metal foams. The research was conducted in horizontal channel with an internal diameter of 0.02 m and length of 2.61 m. The analysis applied three metal foams with pore density 20, 30, and 40 PPI and porosity typical for industrial applications, changing in the range of 92−94%. The experimental data were used to develop a new method for predicting void fraction in two-phase gas−liquid flow in channels packed with metal foams. A new gas void fraction calculating method based on drift-flux model was developed. This model gives a correct representation of changes in the gas void fraction value and good prediction accuracy. The average relative error in calculating the air void fraction in two-phase flow is less than 13%, and 86% of experimental points is characterized by an error less than 20%.

Here, we demonstrate the fabrication of a flexible and transparent micro-supercapacitor (MSC), using colorless polyimide (CPI) via a direct laser writing carbonization (DLWC) process. The focused laser beam directly carbonizes the CPI substrate and generates a porous carbon structure on the surface of the CPI substrate. Fluorine, which is one of the chemical compositions of CPI, can enhance the specific area and the conductivity of the carbon electrode by creating micropores in carbon structures during carbonization. Thus, the fabricated carbonized CPI-based MSC shows enhanced specific capacitance (1.20 mF at 10 mV s−1) and better transmittance (44.9%) compared to the conventional PI-based MSC. Additionally, the fabricated carbonized CPI-based MSC shows excellent cyclic performance with minimal reduction (<~10%) in 3000 cycles and high capacitance retention under mechanical bending test conditions. Due to its high flexibility, transparency, and capacitance, we expect that carbonized... [more]