Anaerobic digestion (AD), microalgae cultivation, and microbial fuel cells (MFCs) are the major biological processes to convert organic solid wastes and wastewater in the agricultural industry into biofuels, biopower, various biochemical and fertilizer products, and meanwhile, recycle water. Various nanomaterials including nano zero valent irons (nZVIs), metal oxide nanoparticles (NPs), carbon-based and multicompound nanomaterials have been studied to improve the economics and environmental sustainability of those biological processes by increasing their conversion efficiency and the quality of products, and minimizing the negative impacts of hazardous materials in the wastes. This review article presented the structures, functionalities and applications of various nanomaterials that have been studied to improve the performance of AD, microalgae cultivation, and MFCs for recycling and valorizing agricultural solid wastes and wastewater. The review also discussed the methods that have b... [more]

Nonlinear composite materials serve to homogenize electric fields and can effectively improve the local concentration of the electric field in power systems. In order to study the nonlinear surface conductivity properties of micro-nano epoxy composites, two types of epoxy micro-nano composite specimens were prepared in the laboratory using the co-blending method. The surface conductivity of the composites was tested under different conditions using a high-voltage DC surface conductivity test system. The results show that the surface conductivity of micro-nano structured composites increases and then decreases with the rise of nanofiller doping concentration. The nonlinear coefficient was 1.781 at 4 wt% of doped nanostructured SiC, which was the most significant nonlinear coefficient compared to other doping contents. For the same doping concentration, the micro-nano structured composites doped with nanostructured SiC have more significant surface conductivity at the same test temperatu... [more]

Conducting polymers, such as polyaniline (PANi) and polypyrrole (PPy), and their nanocomposites, are desired in a wide range of applications, including supercapacitors, lithium ion battery, chemical sensors, biosensors, barrier thin films, and coatings, because of their interesting electrical and electrochemical properties. It is well known that the properties of polymer nanocomposites depend on their chemical structure, as well as their microstructure, yet scientists and engineers have not fully understood how to properly control the structure of polymer nanocomposites. In this study, it is shown that the structure of polyaniline−montmorillonite clay nanocomposites (PACN) can be controlled by varying the ammonium persulfate (APS, oxidant) concentration. The structure of polyaniline and Cloisite 20A clay are, therefore, profoundly affected during the synthesis of PACN nanocomposites. The thickness of polyaniline crystal decreased with increasing oxidant concentration. Fourier transform... [more]

Nanostructured materials remarkably improve the overall properties of thermoelectric devices, mainly due to the increase in the surface-to-volume ratio. This behavior is attributed to an increased number of scattered phonons at the interfaces and boundaries of the nanostructures. Among many other materials, nanostructured Si was used to expand the power generation compared to bulk crystalline Si, which leads to a reduction in thermal conductivity. However, the use of nanostructured Si leads to a reduction in the electrical conductivity due to the formation of low dimensional features in the heavily doped Si regions. Accordingly, the fabrication of hybrid nanostructures based on nanostructured Si and other different nanostructured materials constitutes another strategy to combine a reduction in the thermal conductivity while keeping the good electrical conduction properties. This review deals with the properties of Si-based thermoelectric devices modified by different nanostructures and... [more]

In this paper, a new type of microencapsulated phase change materials (MPCMs) with docosane as the core and titanium dioxide (TiO2) as the shell was prepared by in situ polymerization. Its phase transition temperature was approximately 40 °C, and it can be used as a phase change material (PCM) in a low-temperature solar heat collection system. The properties of the new material were examined including the microstructure, the chemical elements on the surface of the microcapsules, and thermal conductivity. In addition, to obtain the optimized formula of the microcapsules, single-factor analysis on the emulsifier type, its mass fraction, ultrasonic oscillation time, pH, and core−shell ratio were performed. The results showed that the MPCMs prepared in this paper had a particle size of 2−5 μm and were spherical. Its surface was uniform and smooth without cracks, and the TiO2 was well dispersed around the docosane, completely coating the docosane without impurities. The MPCMs had good perfo... [more]

Thermal insulation bio-composites made of plant origin by-products as bio-aggregates are one of the ways to decrease the impact of the building and construction sector on CO2 emissions. In this study, three bio-aggregates were analysed for their potential use in the production of bio-composites with potato starch binder. Technologically important properties, such as particle size, shape and compacted bulk density, as well as properties of the resulting bio-composites were identified. The main characteristics of the aggregates are relatively similar: density of 80−100 kg/m3, thermal conductivity of 0.042−0.045 W/m∙K, specific heat capacity of 1240−1330 J/g∙K, kinetic water absorption from 456−584%. This leads to similar basic properties of the produced bio-composites: density around 200 kg/m3, thermal conductivity 0.053−0.062 W/m∙K, specific heat capacity 1250−1450 J/kg∙K, with a difference in compressive strength ranging from 0.2 to 0.8 MPa. Created starch binder and agricultural by-pr... [more]

This investigation shows the results of a coupled numerical and experimental study on the solidification and melting of spherical capsules and the development of correlations for solidification time and melting time with parameters that impact the complete phase change time of nanofluids and water with and without polyethylene glycol inside plastic spherical capsules. Experiments included the investigation of different configurations of plastic spherical capsule diameters, external temperature, the initial temperature of phase change material (PCM), and PCMs. The PCMs used were water, water with a concentration of polyethylene glycol from 10% to 50%, and multi-wall carbon nanotubes functionalized with carboxylic acid group (COOH-MWCNT) with MWCNT at 0.125, 0.25, 0.5, and 1.0%. The simplified model was validated with available experimental results from the present work and from the literature, showing maximum deviations in the range of 0.25 to 12%. The simulation results showed that the... [more]

The furniture industry is one of the most dynamically developing sectors of the Polish economy. Unfortunately, due to national law, it involves producing a significant amount of wood-based waste, which can only be incinerated in installations that meet the requirements for waste incineration or co-incineration plants. This is due to the presence of various types of chemical additives in post-production residues, which increases the emission of hazardous compounds into the atmosphere during combustion. This article presents an analysis of the impact of the use of catalytic additives on the amount of emissions produced from the combustion of wood-based waste. For this purpose, the analyzed material was pelletized by mixing it with the DESONOX catalyst or by spraying the fuel with the DESONOX + H2O solution in a 1:1 ratio. Catalytic substances were introduced into the fuel until a concentration of 0.1% of its mass was obtained. The use of catalysts has significantly reduced CO and NOX emi... [more]

Electric motors play a crucial role in modern industrial and domestic applications. With the trend of more and more electric drives, such as electric vehicles (EVs), the requirements for electric motors become higher and higher, e.g., high power density with good thermal dissipation and high reliability in harsh environments. Many efforts have been made to develop high performance electric motors, such as the application of advanced novel electromagnetic materials, modern control algorithms, advanced mathematical modeling, numerical computation, and artificial intelligence based optimization design techniques. Among many advanced magnetic materials, soft magnetic composite (SMC) appears very promising for developing novel electric motors, thanks to its many unique properties, such as magnetic and thermal isotropies, very low eddy current loss, and the prospect of low-cost mass production. This paper aims to present a comprehensive review about the application of SMC for developing vari... [more]

Two immiscible fluids flows are materialized in science and technology; the combined convection of the two immiscible fluids in a square conduit is reviewed in this study. The nanofluid and pure viscous fluid which do not mix are discussed, and both layers saturated with a porous matrix have different permeabilities. The Dupuit−Forchheimer and Tiwari−Das models are applied to outline the permeability of the layer and nanofluids, respectively. The finite difference method is utilized to find the solutions of conservation equations along with suitable boundary and interface conditions. The boundary condition for the velocity is no slip at all the boundaries, while continuity of velocity and shear stress are used at the interface. The left and right walls are kept at constant but different temperatures, the top and bottom walls are isolated, and the continuity of temperature and heat flux is assumed at the interface. Grashof number, Brinkman number, Darcy number, inertia parameter, permea... [more]

Generally, the unit cell in a proton exchange membrane fuel cell (PEMFC) stack is divided into different zones according to the characteristics of the bipolar plate. There is a zone that has been neglected, which we define as the “neck zone” for the first time in this work. Uneven stress and deformation are prone to appearing in the neck zone due to its unique structure. A three-dimensional finite element model was applied to study the influence of the membrane electrode assembly (MEA) frame materials on the mechanical characteristics of the neck zone. In addition, the sealing and the water−gas transport performances of the neck zone were evaluated via the stress fluctuation and deformation. It was found that even with the commercial polyethylene naphthalate (PEN) frame, a leak point would be generated at the region with the lowest stress, reducing the performance and even causing safety hazards. The invasion rate was proposed to assess the water−gas transport ability. When an inapprop... [more]

The Russian invasion of Ukraine and the resulting warfare within direct proximity to the European Union (EU) have significantly changed the conditions of Europe’s energy policy. Consequently, the energy security agencies and governments have been deliberating over an energy trilemma: the problem of balancing affordability, security, and environmental considerations, with much greater ramifications than before the breakout of the current military conflict. The past structural similarities and differences of the EU member states’ dependence on Russian energy raw materials, and the factors that might have determined those differences, may be among the key drivers of future energy policy choices in Europe and the prospective paths of the European Green Deal (EGD). Historical convergence might encourage an EGD consensus, while divergent past patterns might not allow for such a single direction throughout the EU. The multifaceted research proposed in this paper, from descriptive statistics t... [more]

To address the problem of winding turn-to-turn breakdown faults in 35 kV dry-type transformers in wind farms under overvoltage conditions, this paper establishes a simulation model based on the structural dimensions and material parameters of the transformer windings. The winding distribution parameters were calculated using the finite element method. The transient processes inside the high-voltage coil were calculated by constructing a multi-conductor transmission line model (MTL) that took into account the influence of the secondary winding. The voltage distribution of the winding was analysed for both lightning shock and extra-fast transient overvoltage conditions. The simulation results show that the maximum overvoltage between turns of the transformer winding under lightning shock is 5.282 kV; the maximum overvoltage between turns of the winding under very fast transient overvoltage is 11.6 kV, which occurs between the first 2−3 layers of the section, close to the insulation break... [more]

Insulation cellulose paper is a basic measure for a power transformer’s remaining useful life, and its advantageous low cost, electrical, and mechanical properties have made it an extensive insulation system when impregnated in a dielectric liquid. Cellulose paper deteriorates as a result of ageing due to some chemical reactions like pyrolysis (heat), hydrolysis (moisture), and oxidation (oxygen) that affects its degree of polymerization. The condition analysis of cellulose paper has been a major concern since the collection of paper samples from an operational power transformer is almost impossible. However, some chemicals generated during cellulose paper deterioration, which were dissolved in dielectric liquid, have been used alternatively for this purpose as they show a direct correlation with the paper’s degree of polymerization. Furthermore, online and non-destructive measurement of the degree of polymerization by optical sensors has been proposed recently but is yet to be availab... [more]

The phase change material is a hot research topic in solar thermal storage systems. However, the thermal conductivity of pure phase change materials is usually low, which hinders its application in facilities. In this study, copper foam is used to increase the thermal characteristics of the paraffin. Simulations are conducted to compare the melting characteristics of the pure paraffin and the paraffin/copper foam composite phase change material. A visualized experimental device was designed and built, and the copper foam composite phase change material, with a volume fraction of 15%, was prepared by filling part of the copper foam in the phase change material. The simulation results agree well with the experimental results. The root mean square errors of the temperature for the pure paraffin and the composite phase change material are 0.0223 and 0.0179, respectively. The experimental results show that the copper foam can enhance thermal conductivity and decrease melting time. It takes... [more]

The wheel was the first form of transportation developed by early people. Increasing population, longer distances, and shorter travel times need more cheap, faster modes of transportation. Environmental issues were never taken into account when choosing the most cost-effective mode of public transportation. Consequently, in the face of global pollution and warming restrictions, all stakeholders choose modes of transportation with little environmental impact. This has led to the development of sustainable transportation infrastructure, particularly in a country as rapidly developing as India. This paper examines the present situation, legislation, and grading systems for sustainable transportation in India and other developing nations. Furthermore, comparisons of India with developing nations of various continents in different aspects are also present. The difference in cost between a private car and a public vehicle indicates which form of transportation should be chosen. The challenge... [more]

The work presented here investigates the risk of interstitial condensation between the existing masonry and the insulation using several materials and evaluates the water content inside the insulation (WCI) through various simulations in dynamic mode onto existing buildings located in different countries in Europe. The insulation materials considered are specifically: natural fibre materials, mineral fibre materials, and artificial materials. The scenarios were chosen considering different climate zones, according to the Köppen climate classification, and the analysed buildings were taken from the TABULA database in the years of construction from 1945 to 1969. The building typologies are single-family houses, where in each building system the insulation was placed towards the warm side with a fixed thickness of 5 cm. The simulations concerned: (a) the application scenario, (b) the type of stratigraphy chosen, and (c) the exposure of the existing building system. The outputs generated b... [more]

Energy storage is becoming a critical issue due to the diminishing availability of fossil fuels and the intermittent nature of current renewable energy sources. As a result, thermal management (TM) and thermal energy systems have gained significant attention due to their crucial roles in various industries. Among the different TM materials, MXenes, a member of the transition metal carbide/nitride family, have emerged as a promising material due to their unique 2D nanostructure, changeable surface chemistry, high electrical/thermal conductivity, light absorptivity, and low infrared emissivity. This review outlines the synthesis methods of MXenes and their various features and applications in thermal management. These 2D materials exhibit outstanding optical and thermal properties, making them suitable for thermal energy generation and storage. The study also covers the potential applications of MXene in the desalination industry, hybrid photovoltaic thermal systems, solar energy storage... [more]

Daytime passive radiative cooling (DPRC) has remained a challenge over the past decades due to the necessity of precisely defined materials with a significantly high emissivity of thermal radiation within the atmospheric transparent window wavelength range (8−13 μm) as well as high reflectivity in the solar spectrum (0.2−3 μm). Fortunately, recent advances and technological improvements in nanoscience and metamaterials are making it possible to create diverse metamaterials. This enables the production of DPRC in direct solar irradiation. The development of a material that is appropriate for effective DPRC is also a noteworthy development in this field of technology. This review gives a thorough introduction and discussion of the fundamental ideas, as well as the state-of-the-art and current trends in passive radiative cooling, and describes the cutting-edge materials and various photonic radiator structures that are useful in enhancing net cooling performance. This work also addresses... [more]

Domestic water heating accounts for 15% to 27% of the total energy consumption in buildings in Australia. Over the past two decades, the latent heat thermal energy storage (LHTES) system has been widely investigated as a way to reduce fossil fuel consumption and increase the share of renewable energy in solar water heating. However, the research has concentrated on the geometric optimisation of the LHTES heat exchanger for the past few years, and this might not be sufficient for commercialisation. Moreover, recent review papers mainly discussed the development of a particular heat-transfer improvement technique. This paper presents perspectives on various solar hot water systems using LHTES to shift focus to on-demand performance studies, as well as structure optimisation studies for faster commercialisation. Future challenges are also discussed. Since the topic is an active area of research, this paper focuses on references that showcase the overall performance of LHTES-assisted solar... [more]

For this study, we conducted a systematic review of the literature on digitalization in energy production, distribution, and consumption over a sufficiently long period in order to reveal the trends and particularities of this phenomenon at the sectoral level. For the systematic review of the literature, representative articles on the subject indexed in the Web of Science and Scopus databases were selected using the PRISMA 2020 flow diagram. As a result of the systematic review of the literature, a significant number of articles on the subject of digitalization in the energy sector were found—both over the entire period considered and especially in the last five years—indicating the magnitude of the digitalization process in this field. The impacts of digitalization in the energy production, distribution, and consumption sectors materialized in the aspects of health, safety, and environmental improvement; process improvements; and cost reductions. The most important technologies used i... [more]

The fabrication of high-capacity, binder-free Li−ion battery anodes using a simple and efficient manufacturing process was reported in this research. The anode material for lithium−ion batteries utilized is a combination of two-dimensional (2D) carbon nanowalls (CNWs) and Cu nanoparticles (improved rate performance and capacity retention) or Si (high capacity) nanoparticles. A methane (CH4) and hydrogen (H2) gas mixture was employed to synthesize CNWs on copper foil through microwave plasma-enhanced chemical vapor deposition (PECVD). The Cu or Si nanoparticles were then deposited on the CNW surface using an RF magnetron sputtering equipment with four-inch targets. To analyze the electrochemical performance of the LIBs, CR2032 coin-type cells were fabricated using anode materials based on CNWs and other components. It was confirmed that the Cu−CNW demonstrates improved rate performance, increased specific capacity, and capacity retention compared with traditional anodes. Additionally, C... [more]

Organic solar cells (OSCs) represent a promising emerging photovoltaic technology offering such benefits as light weight, mechanical flexibility, semitransparency, environmental friendliness and aesthetic design of solar panels. Furthermore, organic solar cells can be produced using scalable and high-throughput solution-based printing and coating technologies, which are expected to lead to very low product costs. Fullerene derivatives have been used as acceptor materials in virtually all efficient organic solar cells for more than two decades, following the demonstration of the first proof-of-concept devices in the middle of 1990s. Still, the power conversion efficiencies of fullerene-based organic solar cells became stuck at around 12% due to the suboptimal optoelectronic properties of conventional fullerene acceptors. Therefore, the latest efficiency records (>18%) for organic solar cells were set using different types of non-fullerene acceptor (NFA) materials with tailorable propert... [more]

This perspective article aims to identify key research priorities to make the waste-to-energy sector compatible with the societal goals of circularity and carbon neutrality. These priorities range from fundamental research to process engineering innovations and socio-economic challenges. Three focus areas are highlighted: (i) the optimization of flue gas cleaning processes to minimize gaseous emissions and cross-media, (ii) the expansion of process control intelligence to meet targets for both material recovery and energy recovery, and (iii) climate neutrality, with the potential for negative emissions via the removal of atmospheric carbon dioxide across the full cycle of the waste resource. For each area, recent research trends and key aspects that are yet to be addressed are discussed.

The concern with the best energy performance of buildings is a current theme, and construction materials that bring improvements to the performance of buildings and their surroundings are in demand. Façades play a crucial role in regulating the temperature within buildings by permitting or obstructing the transfer of heat and also affect the ambient temperature. Light-colored façades help maintain environments with milder temperatures, but pollution, rain, and other degrading agents darken the colors of the façades, reducing their capacity of sunlight reflection. In this scenario, the present study analyzed the addition of different types of titanium dioxide, anatase and rutile, in cement tiles for building façades, combining the ease and speed of assembly with the self-cleaning effects of photocatalysis. The 1 cm thick tiles were produced with a 1:3 mortar ratio (cement:sand/dry aggregate) with a 0.5 water:cement ratio and the addition of 0.3% polypropylene fiber. Different admixture... [more]