Because of the social, economic, and environmental issues linked with fossil resources, there is a global interest in finding alternative renewable and sustainable resources for energy and materials production. Biomass could be one such renewable material that is available in large quantities. However, biomass physicochemical properties are a challenge for its industrial application. Recently, the torrefaction process was developed to improve the fuel characteristics of biomass. However, in recent days, energy production has slowly been shifting towards solar and wind, and restrictions on thermal power plants are increasing. Thus, there will be a need to find alternative market opportunities for the torrefaction industry. In that regard, there is a quest to find alternative applications of torrefaction products other than energy production. This paper presents a couple of alternative applications of torrefied biomass. Torrefaction process can be used as a biomass pretreatment option fo... [more]

The production of biochar from biomass and industrial wastes provides both environmental and economic sustainability. An effective way to ensure the sustainability of biochar is to produce high value-added activated carbon. The desirable characteristic of activated carbon is its high surface area for efficient adsorption of contaminants. Feedstocks can include a number of locally available materials with little or negative value, such as orchard slash and crop residue. In this context, it is necessary to determine and know the conversion effects of the feedstocks to be used in the production of activated carbon. In the study conducted for this purpose; several samples (piñon wood, pecan wood, hardwood, dried grass, Wyoming coal dust, Illinois coal dust, Missouri coal dust, and tire residue) of biomass and industrial waste products were investigated for their conversion into activated carbon. Small samples (approximately 0.02 g) of the feedstocks were pyrolyzed under inert or mildly oxi... [more]

This paper presents a prototype of a low-cost two-phase axial-gap transverse flux generator, in which the magnetic and electric circuits have been made of reused materials, and the stator housing has been manufactured by 3D printing of plastic. Therefore, this work presents as a novelty the combination of the novel transverse flux topology and two challenging trends in electrical machines manufacturing, such as reusing of components and additive manufacturing. Axial-gap transverse flux machines potentially enable the combination of two of the main advantages of axial flux machines and transverse flux machines, i.e., short axial length and a high number of poles. The two-phase arrangement with shared air gap is of great interest in order to reduce further the axial length while avoiding the use of magnetic materials in the rotor, such as iron or soft magnetic composites. However, the equivalent air gap might be large, with significant leakage and fringing effects as the magnetic flux cl... [more]

A sustainable approach to ensuring the thermal regulation of space is reliable with phase change materials (PCMs) operating at 15−25 °C. Henceforth, there is a need of a search of binary and ternary eutectic PCMs operating at desirable phase transition temperatures of 15−25 °C, high energy storage enthalpy (180−220 J/g), improved thermal conductivity and better absorptivity of solar energy. In this current research, we developed a ternary eutectic inorganic salt hydrate PCM intended for a low-temperature thermal regulation system. Based on the eutectic melting point theory, the phase transition temperature and proportion of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD) and sodium sulphate decahydrate (SSD) were determined. As per the calculated proportion, ternary eutectic PCM was experimentally prepared. Furthermore, to enhance the thermal property, graphene nanoplatelets (GNP) were dispersed at weight concentrations of 0.4%, 0.7% and 1.0%. The prep... [more]

A proton exchange membrane fuel cell (PEMFC), as an efficient energy conversion device, has many advantages, such as high energy conversion efficiency and environmentally friendly zero emissions, and is expected to have great potential for addressing the uneven distribution of global green energy. As a core component, the performance of the proton exchange membrane (PEM) directly affects the overall output of the fuel cell system. At present, Nafion membranes with good, comprehensive properties are the most widely used commercial proton exchange membrane materials. However, Nafion membranes demonstrate a great inadaptability with an increase in operating temperatures, such as a rapid decay in proton conductivity. Therefore, enhancing the overall performance of Nafion membranes under high temperatures and low relative humidity (RH) has become an urgent problem. Although many efforts have been made to solve this problem, it is difficult to find the balance point between high-temperature... [more]

In a casing-cement sheath-formation system, the cement−formation interface is usually weakly cemented for the residual of drilling mud, in which a leakage path would easily form, threatening the safe operation of underground energy exploitation and storage. To evaluate the compressive and shear mechanical behavior of the cement−formation interface, cement−rock composite cylindrical specimens were prepared. Uniaxial and triaxial compression and direct shear tests were implemented. The flushing efficiency of the rock surface, compressive strength, interface incompatible deformation, parameters of shear strength, and morphology of shear failure surface were acquired and analyzed. Results show that the flushing efficiency of shale surface decreases from 76.7% to 64.2% with the surface roughness increasing from 0 to 2 mm. The flushing efficiency of sandstone is only 44.7%, remarkably lower than that of shale. With the stress condition transforming from uniaxial to triaxial compression, the... [more]

The present study is focused on the synthesis of zirconium dioxide (ZrO2) nanomaterials using the hydrothermal method assisted by microwave irradiation and solution combustion synthesis. Both synthesis techniques resulted in ZrO2 powders with a mixture of tetragonal and monoclinic phases. For microwave synthesis, a further calcination treatment at 800 °C for 15 min was carried out to produce nanopowders with a dominant monoclinic ZrO2 phase, as attested by X-ray diffraction (XRD) and Raman spectroscopy. The thermal behavior of the ZrO2 nanopowder was investigated by in situ XRD measurements. From the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, the presence of near spherical nanoparticles was clear, and TEM confirmed the ZrO2 phases that comprised the calcinated nanopowders, which include a residual tetragonal phase. The optical properties of these ZrO2 nanopowders were assessed through photoluminescence (PL) and PL excitation (PLE) at room temp... [more]

This work aimed to synthesize biodiesel from Ricinus communis L., using calcium oxide (CaO) nanoparticles as a catalyst. The CaO nanoparticles were examined by scanning electron microscopy (SEM) and X-Ray Diffraction (XRD). The physico-chemical properties of biodiesel were studied through H and C-NMR, GC-MS, FT-IR, and fuel properties were studied according to ASTM and EN standard methods. The oil content of the feedstock was 53.7% with a free fatty acid (FFA) content of 0.89 mg KOH/g. The suitable condition for the optimum yield (89%) of biodiesel was 1:15 of oil to methanol using 20 mg of catalyst at a temperature of 60 °C for 80 to 100 min of reaction time. The H and C-NMR confirm the biodiesel synthesis by showing important peaks at 3.661, 2.015−2.788, 24.83−34.16 and 174.26 and 130.15 ppm. Similarly, GC-MS spectroscopy confirmed 18 different types of fatty acid methyl esters (FAME) in the biodiesel sample. FT-IR spectroscopy confirmed the synthesis of biodiesel by showing characte... [more]

Most power transformers are oil-immersed transformers for which its insulation system consists of oil and cellulosic solid. The insulation liquid impregnates the solid-covering air spaces, which improves the efficiency of the insulation system. Not only does the oil ensure electrical insulation but it also works as coolants transferring the heat generated during transformer operation to the exterior of the transformer. Throughout normal operation conditions, transformers experience multiple stresses that degrade their insulation. Since the lifetime of oil-immersed transformers is defined mainly by the state of the insulation paper, it is critical to understand the behavior and degradation mechanisms of new insulation systems that try to overcome the drawbacks of mineral oil as well as to improve power transformer performances. The current increased prevalence of the nonlinear loads additionally stresses power transformers, which generates their premature ageing or even failure. Consequ... [more]

The anchoring quality of bolts is related to roadway safety and the surrounding rock stability. Due to the limitations of conventional monitoring methods in capturing strain, there still exists a gap in the real-time perception of the mechanical properties of bolts at the micro-scale. This paper proposes a new approach to detecting bolts’ anchoring qualities based on the fiber Bragg grating sensing principle. Moreover, it studies the strain transmission mechanism between the surface-bonded fiber Bragg grating and the bolt. A fiber-optic monitoring test platform of anchor bolt anchoring quality is built. The full-length anchor bolt’s strain evolution law and axial force distribution characteristics are studied during the pull-out test. The study results have shown that the theoretical value of the fiber strain transfer coefficient can be used to calculate the strain of the bolt. The bolt pull-out test verified the accuracy of using the fiber Bragg grating bolt axial force characterizati... [more]

The liquid chemical hydrogen storage technology has great potentials for high-density hydrogen storage and transportation at ambient temperature and pressure. However, its commercial applications highly rely on the high-performance heterogeneous dehydrogenation catalysts, owing to the dehydrogenation difficulty of chemical hydrogen storage materials. In recent years, the chemists and materials scientists found that the supported metal nanoparticles (MNPs) can exhibit high catalytic activity, selectivity, and stability for the dehydrogenation of chemical hydrogen storage materials, which will clear the way for the commercial application of liquid chemical hydrogen storage technology. This review has summarized the recent important research progress in the MNP-catalyzed liquid chemical hydrogen storage technology, including formic acid dehydrogenation, hydrazine hydrate dehydrogenation and ammonia borane dehydrogenation, discussed the urgent challenges in the key field, and pointed out t... [more]

The conventional fracture in shale hydraulic fracturing belongs to the type-I fracture, and the size of the fracture process zone (FPZ) is an important index to measure the fracability of rock mass. This index is also one of the feasible entry points to study the complexity of the fracture network. In order to visually observe the type-I FPZ at the tip of shale fractures, and to study the relationship between the mechanical properties, the shape and size of the FPZ, and the bedding structure, Notched Semi-Circular Bend (NSCB) tests were conducted with three typical fracture direction-bedding orientations (splitter, arrester, divider). The digital image correlation (DIC) method was used to realize the intuitive observation of the real fracture process and the FPZ near the fracture tip. The test found that the FPZ of shale is narrow and long as a whole and is “flame-like”. The height-to-length ratio of the FPZ at the fracture tip determines whether bending and deflection happen between t... [more]

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]