Thermal energy storage integration using phase change materials (PCMs) in buildings has great potential for energy conservation and greenhouse gas (GHG) emission reduction. Cutting-edge research and innovative ideas are required when using multilayered PCMs within typical construction materials to take advantage of their heat storage capability over a wide temperature range within buildings. This current study was carried out to experimentally test the efficacy of using dual PCMs RT28HC and RT21HC with different melting temperature ranges (28 °C and 21 °C) under variable thermal loading. The transient thermal response of various PCM-based configurations of concrete and cement blocks at different temperature inputs was obtained to determine the effectiveness of dual PCMs and their optimized configuration under experimental laboratory conditions. The range of the temperature input was varied from 22 °C to 50 °C, suitable for hot climatic conditions such as those in Pakistan. Laboratory a... [more]

Two-dimensional materials have shown great potential for applications in many research areas because of their unique structures, and many 2D materials have been investigated since graphene was discovered. Ultra-thin SiC layers with thicknesses of 8−10 nm and multi-layer SiC films were designed and fabricated in this study. First, the multi-layer SiC films were obtained by the chemical vapor deposition (CVD) method with the addition of boron elements. We found that boron additives showed novel effects in the CVD process. Boron can promote the formation and crystallization of SiC films at low temperatures (1100 °C), resulting in the separation of SiC films into multi-layers with thicknesses of several nanometers. In addition, a formation mechanism for the 2D SiC layers is proposed. The boron mostly aggregated spontaneously between the thin SiC layers. Photoluminescence spectroscopy results showed that the SiC films with multi-layer structures had different bandgaps to normal SiC films. T... [more]

Tandem solar cells have a superb potential to push the power conversion efficiency (PCE) of photovoltaic technologies. They can be also more stable and economical. In this simulation work, an efficient perovskite solar cell (PSC) with Spiro-OMeTAD as a hole transport material (HTM) and with no electron transport material (ETM) to replace the traditional PSC structure is presented. This PSC is then used as a top sub cell together with a copper indium gallium sulfide (CIGS) bottom sub cell to build a tandem cell. The multi-junction solar cell behavior is improved by engineering the technological and physical parameters of the perovskite and HTM. The results show that an n-p heterojunction PSC structure with an ETM free could be a good candidate for the traditional n-i-p structure. Because of such investigations, the performance of the proposed ETM-free PSC/CIGS cell could be designed to reach a PCE as high as 35.36%.

This article includes an overview of the materials and a thorough analysis of the methods that are used to produce dielectric electroactive actuator membranes. The paper also presents extensive results from our experimental studies on two types of addition silicone (Silicone Mold Start 15 and Dragon Skin 10M) that are used to manufacture actuators with different active membranes of thicknesses (165 μm and 300 μm, respectively). This study explored in depth the hardware architectures and methodologies for manufacturing the selected actuators. The displacements of the actuators were compared to their responses to two types of voltage excitation: a step response and a sinusoidal signal with an increasing frequency over time. This paper graphically presents the results that we obtained for all devices, with a particular emphasis on the resonance frequencies. When comparing membranes that had the same thickness (165 μm), it was found that the mean amplitude was higher for silicone membranes... [more]

The transmutation of transuranic (TRU) elements produced by pressurized water reactors (PWRs) can effectively reduce their radioactive hazards. The molten chloride salt fast reactor (MCSFR) is a type of liquid-fueled molten salt reactor (MSR) using fuel in the form of molten chloride salts. The MCSFR utilizing a fast neutron spectrum and high actinide fraction is considered to be a potential reactor type for TRU transmutation. An online refueling and reprocessing scenario is the unique feature of liquid-fueled MSRs. On account of this characteristic, a new fuel management code named ThorNEMFM with a nodal expansion method (NEM) was developed and validated with the molten salt breeder reactor (MSBR) and the molten salt fast reactor (MSFR) benchmarks. Then, the transmutation and breeding performances of the MCSFR were simulated and analyzed with the ThorNEMFM code. The MCSFR adopts TRU elements as initial fissile loads and online feeding fissile materials. The results show that the trans... [more]

Currently, one of the main directions of agricultural development in Poland is the pursuit of sustainable development, rational management of material resources, and striving for energy self-sufficiency, while maintaining low greenhouse gas emissions. It is an alternative to constantly supported coal solutions. Sustainable development in the sense of processes taking place in enterprises affects many key areas of their activity. One of them is the measurement of efficiency, another is the compatibility with nature and the environment, and the perception of humans and their role. Measures of enterprises’ effectiveness should be considered in relation to the objectives of the enterprise. Biorefineries play a special role in shaping the new energy reality, being a system that connects various devices and biomass conversion processes to produce energy, fuel, and other valuable products. The essence of the functioning of biorefineries is as value chains; that is, a series of interrelated ac... [more]

Glycerol, a highly functionalised polyol, can be used as a platform molecule to produce a variety of high-value chemicals. As glycerol production is projected to increase over the coming years, it’s critically important that technology and infrastructure are developed to make use of the inevitable surplus. The catalytic production of ‘green’ mono alcohols from glycerol, in the absence of H2, is an emerging area of research that, in recent years, has generated significant industrial interest. Herein, we provide an update on recent advances in this field and discuss challenges which need to be overcome if this approach is to be considered viable industrially. The economic significance of using crude glycerol as a feedstock for glycerol valorisation strategies is also addressed and suggestions for improving the impact of research conducted in this field are proposed.

TiO2 is seen as a low cost, well-known photocatalyst; nevertheless, its sluggish charge kinetics does limit its applications. To overcome this aspect, one of the recent approaches is the use of its composites with graphene to enhance its photoactivity. Graphene-based materials (nanosheets, quantum dots, etc.) allow for attachment with TiO2 nanostructures, resulting in synergistic properties and thus increasing the functionality of the resulting composite. The current review aims to present the marked progress recently achieved in the use of TiO2/graphene composites in the field of photocatalysis. In this respect, we highlight the progress and insights in TiO2 and graphene composites in photocatalysis, including the basic mechanism of photocatalysis, the possible design strategies of the composites and an overview of how to characterize the graphene in the mixed composites. The use of composites in photocatalysis has also been reviewed, in which the recent literature has opened up more... [more]

Thermal recovery is one of the most effective techniques for viscous oil production, which has been widely used in the heavy oilfield development. The mechanisms and percolation characteristics of thermal recovery have attracted a lot of attention. However, the displacement characteristics and produced oil properties in the steam flood heavy oil process are rarely addressed. In this paper, steam flooding experiments with two heavy oil viscosities under the temperatures from 120 to 200 °C and velocities from 1 to 3 mL/min were carried out to examine the oil displacement efficiency and the produced oil properties. The results show that the majority of the oil is produced in the low water cut stage. Temperature increment is helpful for prolonging the water breakthrough time. The high injection velocity of steam contributes to a high recovery factor, even if it enters into the high water cut stage. The rheology of the produced oils severely changes because the SARA composition changes, and... [more]

The resource orientation of the Iraqi economy implies the development of a competitive advantage of the oil industry through the industry’s infrastructure development. The authors’ assumption is that as a result of the transport and production infrastructures’ development of the extraction, processing and transportation of oil and oil products in the conditions of global economic turbulence and the availability of profitable mineral raw materials, domestic demand is restrained by both “inherited” problems and new challenges for the Iraqi oil industry. A review of changes in oil production over time has been carried out. The following problems have been identified: “inherited” problems of the oil industry’s production infrastructure, insufficient capacities and technologies and unbalanced attraction and use of investments. It has been identified that problems vary with different infrastructures. For transport infrastructure, transportation security threats, the insufficient capacity of... [more]

Recently, as the use of wearable devices and the demand for eco-friendly energy have increased, many studies have been conducted on triboelectric nanogenerators (TENGs), which can economically harvest energy. Paper is considered a promising substrate and frame material that can be used to manufacture self-powered TENGs, owing to its flexibility, low cost, and accessibility. Herein, we present a sandwich-structured foldable paper-based TENG (FP-TENG) that comprises flexible materials and uses paper as a substrate. The FP-TENG can generate up to 572 mW/m2 of power via contact−separation of the triboelectric electrified body at the top and bottom. With more folds of the FP-TENG, the triboelectric cross-sectional area increases, and, thus, the electrical output increases. In addition, the proposed TENG exhibits excellent durability without signal degradation under 5000 cycles of repeated pushing motions. To demonstrate its practicality, the FP-TENG was manufactured in the form of a wristwa... [more]

The huge number of electronic devices called the Internet of Things requires miniaturized, autonomous and ecologically sustainable power sources. A viable way to power these devices is by converting mechanical energy into electrical through electro-active materials. The most promising and widely used electro-active materials for mechanical energy harvesting are piezoelectric materials, where the main one used are toxic or not biocompatible. In this work, we focus our attention on biocompatible and sustainable piezoelectric materials for energy harvesting. The aim of this work is to facilitate and expedite the effort of selecting the best piezoelectric material for a specific mechanical energy harvesting application by comprehensively reviewing and presenting the latest progress in the field. We also identify and discuss the characteristic property of each material for each class to which the material belong to, in terms of piezoelectric constants and achievable power.

This work aims to investigate the influence of temperature and chemical impregnation in the textural and morphological composition of the bio-adsorbent of bio-adsorption via thermal cracking of the seeds of açaí. The experiments were carried out at 400 °C and 450 °C using a pilot scale reactor. The efficiency of the organic process was calculated in terms of liquid and solid products selected with a chemical impregnation process with NaOH, mainly with the liquid that had a greater product conversion. The elementary samples of the solid products occur with the occurrence of carbonization with an increase in the temperature of the process and the presence of impregnation. The textural and morphological characterization occurred with an analysis of FT-IR, SEM/EDS, XRF, and B.E.T. The in-phase product was developed through the creation of açaí seed in nature and impregnated with NaOH solution (2 M) at temperatures of 400 °C and 450 °C. The adsorption kinetics of acetic acid were investigat... [more]

Lignin is the second most abundant renewable natural polymer that occurs on Earth, and as such, it should be widely utilised by industries in a variety of applications. However, these applications and possible research seem to be limited or prevented by a variety of factors, mainly the high heterogeneity of lignin. Selective modifications of the structure and of functional groups allow better properties in material applications, whereas the separation of different qualitative lignin groups permits selective application in industry. This review is aimed at modification of the lignin structure, increasing the hydrophobicity of the produced materials, and focusing on several perspective modifications for industrial-scale production of lignin-based polymers, as well as challenges, opportunities, and other important factors to take into consideration.

Hydrogen peroxide (H2O2) has demonstrated applicability in a wide range of applications, spanning from a bleaching agent in the pulp industry, environmental remediation, and fuel cell technology. Industrial scale synthesis, either by the anthraquinone method or catalytic oxidation of hydrogen gas, has serious drawbacks which are related with energy demanding and multi-step processes. An alternative green strategy involves the photocatalytic synthesis of H2O2. All that is needed is the renewable energy of the sun, a semiconducting species absorbing in the visible region, water, and oxygen. In this minireview, we describe the evolution of research milestones that have been achieved within the recent decades regarding the development of functional photocatalytic systems. In the early studies, back in the 1980’s, TiO2-based systems were mostly investigated. However, due to the large band gap of titania (3.2 eV), alternative semiconductors were studied which strongly absorb in the visible r... [more]

Of the various waste and side streams created in a kraft pulp mill, the biological sludges from the wastewater treatment plant are some of the most problematic to handle. Incineration is becoming a common solution as landfilling is no longer permitted by legislation in many countries, but this is also problematic due to the high moisture content, poor drying characteristics, and high ash content in the solids. This study evaluates the technical potential of mild hydrothermal carbonization (HTC) at 160 °C for 3 h to improve the energy efficiency of on-site incineration as a biosludge handling method. HTC treatment transforms wet organic substrates into a hydrophobic carbonaceous material (hydrochar). The heating value and elemental composition of both the sludge and the hydrochar product were analyzed. Based on this, a hydrothermal carbonization model developed earlier was adjusted for the feedstock, and process integration modelling performed to evaluate the performance impact on the p... [more]

Mechanised plow and shearer systems are widely applied in underground mines all over the world. Both systems are used in the exploitation of hard coal deposited in the form of seams of various thickness. The selection of the appropriate complex depends on the mining and geological conditions and the thickness of the seam. However, with regard to thin and medium seams, these complexes are competitive solutions. Mines usually use either shearer or plow systems. Both have certain advantages and disadvantages resulting from their design and method of operation, which have been demonstrated and presented in many publications. However, in terms of their failure rate comparison, there are no relevant research and analysis results. Only selective studies of individual machines can be found. The article is concerned with the failure frequency of longwalls equipped with plow and shearer systems in the LW Bogdanka coal mine. The analysis covers a period of 13 months of the mine’s operation, durin... [more]

Molybdenum disulfide (MoS2) has attracted great attention from researchers because of its large band gap, good mechanical toughness and stable physical properties; it has become the ideal material for the next-generation optoelectronic devices. However, the large Schottky barrier height (ΦB) and contact resistance are obstacles hampering the fabrication of high-power MoS2 transistors. The electronic transport characteristics of MoS2 transistors with two different contact structures are investigated in detail, including a copper (Cu) metal−MoS2 channel and copper (Cu) metal−TiO2-MoS2 channel. Contact optimization is conducted by adjusting the thickness of the TiO2 interlayer between the metal and MoS2. The metal-interlayer-semiconductor (MIS) structure with a 1.5 nm thick TiO2 layer has a smaller Schottky barrier of 22 meV. The results provide insights into the engineering of MIS contacts and interfaces to improve transistor characteristics.

The paper analyzes the influence of the material from which the ferromagnetic core of a transformer is made on the characteristics of a full-bridge converter. Experimental investigations were carried out for three bridge converters containing transformers with ring cores made of various materials: iron powder, ferrite, and nanocrystalline material. The properties of the aforementioned converters were considered in a wide range of changes of input voltage, load resistance, as well as frequency and the duty cycle of the control signal. Based on the obtained measurements results of the relationship between the parameters of the used transformer core and the obtained values of the output voltage, the energy efficiency of the full bridge converter was discussed. The method of transformer modeling in the SPICE program for the analysis of the considered converter in this program was proposed. The correctness of this model was demonstrated for a converter containing a transformer with a powder... [more]

Pneumatic conveying is widely used in coal mining. As the lowest conveying velocity of materials, the pickup velocity is the key to the study of gas−solid two-phase flow. In this study, the pickup velocity of pebble particles was experimentally investigated. When the particle size is 3−9 mm, the airflow velocity was found to suitably describe the results as a function of the pickup velocity and have a high correlation. When the swirl number is 0.2, the optimal swirl number was found for which the highest particle pickup ratio was observed. Based on four different methods, namely, visual observation, mass weighing, coefficient of difference analysis, and determination of the peak-average ratio of the pressure drop in the flow field to measure the pickup velocity of the spraying material, the results showed that the accuracy of the particle pickup velocity obtained through visual observation was the lowest, and when the mass−loss rate of the particle was selected as the measurement index... [more]

In industrial-scale biogas production from cereal straw, large quantities of solid fiber-rich digestate are produced as residual material. These residues usually contain high amounts of cellulose, hemicellulose and lignin and thus have potential for further utilization. However, they also contain impurities such as ammonia and minerals, which could negatively affect further utilization. Against this background, the present study investigates how this fibrous straw digestate can be fractionated by a combined hydrothermal and enzymatic treatment and what influence the impurities have in this process. Therefore, it is analyzed how the fractions cellulose, hemicellulose and lignin are modified by this two-stage treatment, using either raw digestate (including all impurities) or washed digestate (containing only purified fibers) as the substrate. For both substrates, around 50% of the hemicellulose is solubilized to xylans after 50 min of hydrothermal treatment using steam at 180 ∘C. Furthe... [more]

Harvesting atmospheric water by solar regenerated desiccants is a promising water source that is energy-efficient, environmentally clean, and viable. However, the generated amounts of water are still insignificant. Therefore, more intensive fundamental research must be undertaken involving experiments and modeling. This paper describes several experiments, which were conducted to predict and improve the behavior of water absorption/desorption by the Calcium Chloride (CaCl2) desiccant, where the uncertainty did not exceed ±3.5%. The absorption effect in a deep container was studied experimentally and then amplified by pumping air into the solution. The latter measured water absorption/desorption by a thin solution layer under variable ambient conditions. Pumping air inside deep liquid desiccant containers increased the water absorption rate to 3.75% per hour, yet when using a thin layer of the solution, it was found to have increased to 6.5% per hour under the same conditions. The maxim... [more]

Silica is considered one of the most prevalent components in the Earth’s shell and is synthesized for use in technological applications. Nevertheless, new methods for finding a better, cheaper, and more ecologically friendly supply of silica with less energy consumption are unavoidable. This study investigates whether nanopowders made from waste with a great silica amount (fly ash and glass) can be utilized as fillers in an epoxy glue to enhance its characteristics. Four different contents (5, 10, 15, and 20 wt%) of nano−fly ash, nanoglass, and nanosilica powder were introduced into the samples. Fourier transform infrared analysis, differential scanning calorimetry analysis, viscosity testing, and microhardness testing were conducted for nanoglass/epoxy and nano−fly ash/epoxy samples, which were compared with the silica/epoxy samples. Results indicated that the nanoglass and nano−fly ash powder have the same impact as nanosilica on the characteristics of epoxy. The hardness and viscosi... [more]

Long linear antennas for very low frequency radio transmissions, supported by aerostats, unanchored, and raised to high altitudes, present themselves as slow-moving, highly conductive disturbances in cloud layers, acquiring an electrical charge and being subjected to intense coronae. High electric field strength values around those objects increase the risk of lightning strikes, which could be disastrous to the mechanical structures of the balloon mission (both the antenna and the balloon) and the radio transmitter. This paper aims to investigate the inception of lightning strikes over two essential elements of such missions: a talc-covered latex (balloon material) and the model of the linear antenna, made of different materials. Based on the high-voltage experiments with the recorded electrical discharges, the properties, functions, and possible ameliorations of the talc cover are presented, as well as the basic characteristics of lightning forms around the very long antenna system, w... [more]

This paper introduces a fiber generator using PVDF with a high-performance lead-free piezoelectric ceramic as filler. The piezoelectric ceramic filler was Ba0.84Ca0.16Ti0.90Zr0.10O3 + CuO 0.25 wt% (BCTZC0.25) sintered at 1550 °C. The BCTZC0.25 has an improved high-energy conversion constant (d33 × g33). The fiber generator made of PVDF/BCTZC0.25 composite fiber showed 1.6 times better piezoelectric power generation performance compared to a pure PVDF fiber generator. The PVDF/BCTZC0.25 fiber generator produced an output voltage of 1.9 V at 4 Hz. Hence, we successfully demonstrated that a composite fiber generator that uses piezoelectric ceramics which are harmless to the human body can outperform a pure PVDF fiber generator.