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The use of dry methods of processing and beneficiation of mineral raw materials is one of the promising areas, as this approach to concentrate production is less energy-consuming, less labor-intensive, and economically beneficial. The paper presents experimental studies on preliminary dry separation of Arkachan deposit ores to determine the quality of beneficiation of the separation products. The studies on dressability were carried out on pilot plants for dry ore processing and beneficiation: combined impact crusher DKD-300, centrifugal mill TsMVU-800, pneumatic separator POS-2000. Processing of the obtained separation products by pneumatic separation and screening according to the sequential flow chart of crushing and grinding was carried out in laboratory conditions at a gravity concentration table SKO-0.5. The GRG test was performed at an ITOMAK-0.1 centrifugal concentrator using a sequential grinding circuit. The GRG test showed that for more efficient gravity separation of gold, up to total gold recovery of 73.91%, the degree of grinding up to 80% passing 0.071 mm was required, allowing obtaining a gravity concentrate graded at 70.28 g/t gold.

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The Controlled transport of tiny particles in a microfluidic environment has attracted the attention of numerous researchers in the field of lab-on-a-chip. In this work, for the first time, a fully operational microfluidic chip composed of asymmetric magnetic tracks that unidirectionally transport multiple magnetic particles synced with a general tri-axial magnetic field is proposed. In this innovative chip, the particle motion is analogous to the electron transport in electrical diodes, with similar controllability and automation levels not seen in other single-particle manipulation systems. The vertical bias component of the magnetic field by providing a repulsive force between the particles and preventing undesired cluster formation, makes the proposed chip even more similar to the electrical circuits. Additionally, the chip functions as a highly sensitive biosensor capable of detecting extremely low levels of DNA fragments using ligand-functionalized magnetic beads. The uniqueness of the proposed sensor lies in the introduction of a novel particle/analyte concentrator based on the proposed diodes, which enhances its detection sensitivity. This sensitivity is even further enhanced by a single-particle and pair detection image processing code. Furthermore, the background noise is reduced by eliminating the unwanted bead cluster formation commonly observed in previous works. The proposed device serves as a high-throughput unidirectional transport system at the single-particle resolution, offering sensitive bio-detection with many applications in biomedicine. [ABSTRACT FROM AUTHOR]

In recent years, notable advancements have been achieved to increase the kesterite CZTSSe solar cells efficiency. The maximum experimental efficiency measured is approximately 13.6%. Compared to other (TFSCs), the current CZTSSe exhibits a low efficiency caused by a significant shortage in opencircuit voltage, and the power conversion current value is still largely lower than the Shockley-Queisser limit (28%). In this regard, this research paper presents a numerical study of CuZnTnSSe solar cell in concentrator application combined with BSF layer to improve its efficiency by using SCAPS-1D software. The solar cell is composed of ZnO/CdS/CZTSSe/Mo arrangement. Firstly, simulation and experimental published data were used for model validation. SnS layer incorporation as back surface field (BSF) results in enhancing its efficiency from 12.54% to 15.84%. Furthermore, BSF and absorber thickness and doping concentration have been optimized, resulting in an efficiency of 20.17% under ideal circumstances. The improved CZTSSe solar cell efficiency rises from 20.17% to 24.10% at 10 suns concentration when the concentrator effect is further examined. Finally, a practical test using a silicon (Si) solar cell with an 8X concentration Fresnel lens was conducted to validate the simulation approach. A similar pattern is shown under the concentration effect in both the simulation and experimental solar cells. The resultant conclusion offers insightful information about the utilization of CZTSSe solar cells in concentrators applications, especially when combined with (BSF) layer. [ABSTRACT FROM AUTHOR]

The facets of the old Mc Donnell Douglas concentrator of Plataforma Solar de Almería –PSA- SF60 solar furnace were degraded after thirty years of service, which had a great influence on its thermal response and efficiency, as the reflectivity decreased significantly due to the reflective surface being corroded and scratched. That is why, it was decided to replace them by new facets with higher reflectivity and better optical conditions. This paper describes the new facets, as well as the new support structure and the assembly and alignment of the concentrator facets. Finally, the technical characteristics of the new concentrator, and the power, size and flux distribution on the focus, are presented. For the new facets we selected a thin, hexagonal-shaped mirror bonded to an aluminum plate. Therefore, new facets with improved optical conditions were designed and manufactured and, for the assembly a new tubular structure was used to conform the new FAHEX100 concentrator To anticipate the behavior of the new FAHEX100 concentrator, a model was built in Tonatiuh, for which a geometric analysis of the facets was previously performed by means of photogrammetry. Once the facets were mounted on the concentrator, they were aligned by the Reverse Ilumination Method -RIM–, and the flux distribution on the focus was measured with a CCD camera. The performance of the SF60 solar furnace was improved significantly with the new FAHEX100 concentrator, including power, peak concentration, flux distribution on the focus, focus diameter and optical error σopt.

This paper presents a passive concentrator for single-phase inverters with a three-phase output, which uses magnetically coupled reactors. Due to the development of renewable energy systems, the proposed systems may enable the easier integration of converters in the form of inverters with the power system. Two variants of cooperation of the concentrator with single-phase voltage inverters were considered. The first variant proposed a system topology in which three single-phase full-bridge inverters were connected to the concentrator, while the other variant proposed six half-bridge inverters. A control system of the inverters that does not use PWM was developed. A common star point was created for the supply voltages in the form of a capacitive divider covering all the inverters. An analysis of the concentrator system was presented, taking into account the cooperation with inverters. The overall power of the TDSλ system was defined and the relationship for its determination was given. Simulation studies were described, presenting the obtained voltage and current waveforms. The impact of changing the supply voltage of the inverters on the operation of the concentrator and the shape of the output voltages was assessed. The proposed systems allow you to connect 3 or 6 single-phase inverters. The use of magnetically coupled reactors enables the use of a magnetic system of lower power and size. The described concentrators enable the generation of multi-level three-phase output voltage with a low THD content. [ABSTRACT FROM AUTHOR]

Featured Application: Moist air wind tunnels are an unknown tool to test, validate theoretical studies, and improve the design of wind turbines under different weather conditions. The present research work shows how a functional subsonic moist-air wind tunnel has been designed. Although this type of wind tunnel has never been developed to date, it is particularly interesting to develop a satisfactory design of feasibility under moist air conditions. Low-speed vertical-axis wind turbines employ different kinds of rotors, such as Savonius, Darrieus, and H-rotor. All these wind turbines present clear advantages, e.g., the horizontal-axis wind turbines are omnidirectional. This means they can work under different wind directions, need lower maintenance, and begin working under low wind speeds of 3 m/s. Recently, a new application of wind concentrators enabled the vertical-axis wind turbines to improve their performance coefficient based on new concepts like moist air phase change, which are being analysed to improve energy conversion. Thus, expectations were raised to design a suitable wind tunnel that accounts for the relative humidity of moist air. An initial prototype showed that the behaviour of open wind tunnels where the relative humidity of moist air was controlled by an adiabatic evaporative process was satisfactory. However, for such wind tunnels, certain improvements like computer control systems would need to be developed. [ABSTRACT FROM AUTHOR]

In this paper, we presented a simulation method to assess and evaluate the performance of a simple optical design composed of a split spectrum combined with a solar concentrator, both spectrum splitter and solar concentrator, which are commonly numerically designed and optimized on Trace Pro. A comprehensive explanation based on numerical simulation using ray tracing with realistic irradiation conditions is presented to demonstrate the possibility of employing a spectrum-splitting system to improve solar energy conversion and to explain the essential importance of optical concentration in such a system. The analysis demonstrates an increase in electricity efficiency, and the [Yellow Green] spectral range shows the most effective absorption for silicon solar cells compared to [Red Orange] and [Blue Purple] spectral ranges. The solar cells get an additional performance boost from the concentration incorporated. The following approach is expected to result in a more usable design, it allows for more efficient use of solar energy and potentially achieves much higher conversion efficiencies, a way of reducing production costs and increasing the output of the photovoltaic cell. [ABSTRACT FROM AUTHOR]

One of the most important challenges in information networks is to gather data from a larger set of nodes to a smaller set of nodes. This can be done via the use of a concentrator architecture in the connection topology. This paper is a proof-of-concept that demonstrates a quantum-based controller in large interconnection networks can asymptotically perform this task faster. We specifically present quantum algorithms for routing concentration assignments on full capacity fat-and-slim concentrators, bounded fat-and-slim concentrators, and regular fat-and-slim concentrators. Classically, the concentration assignment takes O (n) time on all these concentrators, where n is the number of inputs. Powered by Grover's quantum search algorithm, our algorithms take O (n c ln ⁡ c) time, where c is the capacity of the concentrator. Thus, our quantum algorithms are asymptotically faster than their classical counterparts, when c ln 2 ⁡ c = o (n). In general, c = n μ , satisfies c ln 2 ⁡ c = o (n) , implying a time complexity of O (n 0.5 (1 + μ) ln ⁡ n) , for any μ , 0 < μ < 1. [ABSTRACT FROM AUTHOR]

Introduction: In the field of solar energy utilization, the construction of low cost and easy to process large concentrated photothermal system is a scientific problem to be solved. A linear Fresnel reflection solar concentrator is proposed in this paper.Methods: The position, tilt angle and width of the glass mirrors placed in the same plane are different to ensure that all the reflected light falls on the flat focal plane or cylindrical focal surface. According to the focusing principle of the concentrator, two experimental system platforms ware built. When a flat focal plane is used to receive radiation from the sun, the intensity distribution of focal plane light spot is uniform in theory.Results: The CCD measurement method is used to analyze the concentrated light spot under experimental conditions, and it is proved that the energy flux density on the focal plane is uniform. Placing monocrystalline silicon cells on the focal plane, the experimental results of p-v power generation voltammetry show that the power generation efficiency of monocrystalline silicon cell does not decrease due to the uniform solar energy density, which can reach 17.1%. The photothermal experiment is carried out by using one-dimensional tracking mode of sunlight. The concentrator reflects the sun’s rays onto the vacuum collector tubes, heating the heat conduction oil flow in. The thermocouple measures the temperature of the heat conduction oil at the inlet and outlet of the vacuum collector tubes. The experimental photothermal conversion efficiency of this concentrator was analyzed and calculated through multiple groups of photothermal experiments, and compared with the theoretical concentrator efficiency. With two collector tubes in series, the theoretical photothermal conversion efficiency reaches 0.8 and the experimental photothermal conversion efficiency reaches about 0.74.Discussion: Because of its good concentrating performance and low cost, this type concentrator can be widely used in photothermal and photovoltaic applications.

Classical solar-pumped lasers often demand a significant amount of concentrated solar power for laser emission, which is only attainable under clear sky condition, limiting their applicability. In this research, we report the first solar laser emission at very low threshold solar power under cloudy sky condition by end-side-pumping a 2.5 mm diameter, 25 mm length Ce:Nd:YAG rod at the focus of a parabolic mirror concentrator. The Ce:Nd:YAG solar laser performance was also evaluated under clear sky condition for comparison. Low threshold pump power of 32.4 W for continuous-wave solar-pumped laser was obtained under clear sky condition, being two times lower than the previous record. However, the cloud-filtered infrared sunlight enabled notable improvements in the solar laser performance by lessening the thermal lensing effects in the laser medium. The threshold pump power was further reduced to 29.2 W and maximum solar laser output of 14 W was successfully measured. This nearly doubled the focal slope efficiency from 4.03% during clear weather to 7.71% under a cloudy sky. The solar-to-laser conversion efficiency of 6.32% was nearly tripled compared to the 2.32% on a clear sky, while the solar laser conversion efficiency of 21.47 W/m2 was nearly twice the value of 12.62 W/m2 obtained on a clear day. This demonstrates that a cloudy environment could be an asset for solar laser research. [ABSTRACT FROM AUTHOR]

To improve the concentration performance of the concentrator in the iron ore beneficiation process for iron ore tailings, a coupled simulation analysis of the concentration process was conducted using the discrete element software EDEM (Engineering Discrete Element Method) and the finite element FLUENT software. The volume concentration at the bottom flow outlet of the concentrator was used as the evaluation index. The scraper rotation speed, feed rate, and feed concentration were considered as parameters. Response surface experiments were designed using the Box-Behnken module in Design Expert11 software, and numerical simulations were performed to obtain data. Based on the numerical simulation results, a prediction model was established using the backpropagation neural network (backpropagation neural network, BP-NN) and combined with the genetic algorithm (genetic algorithm, GA) for parameter optimization of the thickener's concentration conditions. The results showed that with a scraper rotation speed of 9.7677 rpm, feed rate of 0.2037 m/s, and feed concentration of 6.5268%, the maximum outlet volume concentration reached approximately 62.00%. The predicted optimal working conditions were validated through physical tests and numerical simulations. The average outlet volume concentration in the physical tests was 60.712% (n = 10) ("n" is the number of experiments), with an error of only 2.077% compared to the predicted value. The middle outlet volume concentration in the numerical simulation experiments was 59.951% (n = 10), with an error of only 3.304% from the expected value. These results demonstrate the feasibility of using a genetic neural network for optimizing the EDEM–FLUENT simulation parameters of the thickener, providing valuable insights for the matching optimization of the thickener's process parameters. [ABSTRACT FROM AUTHOR]

The article proposes a technological scheme for the process of obtaining alternative fuels from local biomass by the method of heliopyrolysis. Besides, the temperature regime in the reactor of the pyrolysis device and the thermal energy savings consumed for the specific needs of the device, as well as the thermal performance of the device are analyzed. It is known that reducing energy consumption in pyrolysis technology is a major challenge because energy (heat) must first be supplied to maintain the reactor temperature regime. Typically, the processes carried out in a pyrolysis unit are carried out at the expense of coal, natural gas or electricity consumption. For the operation very large amount of thermal energy is required to decompose biomass waste, and additional heating of biomass requires excessive energy consumption. To prevent these technological problems, the article proposes a solar concentrator’s heliopyrolysis system to heat the pyrolysis reactor. Applying a solar concentrator to this type of pyrolysis device can achieve a temperature of 400–700 °C. A schematic diagram of the experimental pyrolysis unit of the solar concentrator was developed, and samples of alternative fuels (pyrogas, liquid, solid fuels) were obtained as a result of thermal processing of biomass. Based on the analysis of the material balance of a heliopyrolysis plant with a parabolic-cylindrical solar concentrator, it was found that about 20 % pyrogas, 60 % liquid fuel, 8–20 % solid alternative fuel were obtained during the pyrolysis of cotton stalks with an initial biomass load of 3.76 kg. In order to determine the consumption of thermal energy in the pyrolysis process, as well as for the replaced solar energy, an analysis of the heat balance of the proposed installation was carried out. It is shown that the use of a solar concentrator makes it possible to reduce the specific energy consumption for the pyrolysis process by up to 30 %. The proposed heliopyrolysis device makes it possible to reduce the consumption of thermal energy for own needs, increase the overall efficiency of the installation and ensure a stable temperature regime for pyrolysis.

Abstract Solar energy is an inexhaustible renewable energy resource, which is a potential solution to global warming and aids sustainable development. The use of solar-thermal collectors to harness solar energy facilitates low-cost heat storage and can improve the stability of power grids based on renewable energy. In solar-thermal collectors, traditional concentrators, such as parabolic troughs and dishes, are typically used but inevitably require high-precise supports and complex tracking sun systems, which increase the cost of solar-thermal power stations and hinder their further applications. In contrast, planar meta-lenses (so-called metasurface-based concentrators) consisting of two-dimensional nanostructured arrays are allowed to engineer the frequency dispersion and angular dispersion of the incident light through delicately arranging the aperture phase distribution, thereby correcting their inherent aberrations. Accordingly, the novel meta-lenses offer tremendous potentials to effectively capture broadband, wide-angle sunlight without the extra tracking system. This review summarizes the research motivation, design principles, building materials, and large-area fabrication methods of meta-lens for solar energy harvesting in terms of focusing efficiency, operation bandwidth, and angular dependence. In addition, the main challenges and future goals are examined.

In this paper, the feasibility and performance of using solar arrays equipped with sun concentrators, along with other conventional solar array structures, in CubeSats, is investigated for the first time. For this purpose, seven different structures of solar arrays have been defined and implemented for more than 24 different CubeSat configurations from 0.25U to 27U. Then, by calculating important system-level parameters such as power generation density, power generation cost, reliability of solar arrays, and also a newly proposed parameter, called shape fit factor, the performance of these structures for the introduced configurations are evaluated and compared. To this end, and by considering rational coefficients, a cost function consisting of the four above-mentioned parameters is defined as the degree of merit of different solar array structures used in each CubeSat configuration. The results show that alongside the use of deployable solar arrays, using concentrating solar arrays can provide new capabilities for CubeSats to overcome the challenge of generating sufficient power.

The work is devoted to the solution of the currently topical problem of introduction into mass production and operation of solar energy systems for the primary processing of agricultural products. Technological processes related to the processing of agricultural products are often quite energy-intensive and require significant consumption of thermal and electrical energy, which have a high cost. Therefore, their replacement with solar radiation energy could give a significant economic effect. Solar energy systems are able to satisfy a wide range of consumer needs, primarily in the field of production and processing of agricultural products, such as hot water supply, heating, drying of agricultural products and various materials, etc. However, today, solar power plants are rarely used to provide energy for the aforementioned technological processes. One of the main reasons for this is the absence of a single system of standardization and unification of solar thermal energy systems. In order to solve this problem, this paper proposes a complex of modular solar energy systems intended for energy supply to consumers of the agro-industrial sector of the economy. It is a universal set of unified modules and blocks, by means of which it will be possible to assemble solar energy systems that differ in functional purpose, power, thermal parameters and overall dimensions. A characteristic feature of this complex will be its high mobility, multifunctionalness, a wide range of technological adjustments, convenience and easiness of operation and maintenance, as well as a relatively low cost. Implementation of this complex will allow to: - reduce the production cost of solar energy systems by approximately 50% and increase their economic profitability by approximately the same amount; - simplify their operational maintenance and reduce the labor-intensiveness of installation and dismantling, thus making solar installations mobile; - expand the field of their application; - significantly simplify the task of organizing multi-series production; - create continuous model series of solar energy systems of various purposes, each of which will include several solar power plants that are identical in terms of their functional purpose, but different in terms of mass, dimensions and capacities. Mass use of the proposed solar systems will provide agricultural enterprises and household consumers with a reduction in the consumption of organic fuel and network electricity, which will lead not only to reduction in the cost of processing agricultural products, but also to reduction in harmful emissions into the environment. [ABSTRACT FROM AUTHOR]

Presented is a new cylindrical waveguide (WG) system based on a two-dimensional photoreceptor-conversion scheme (2DPRCS) for lamppost-type solar-cell systems. The optical properties of polydimethylsiloxane (PDMS) were evaluated as the WG material, and we found that the intrinsic optical loss of our PDMS-based waveguide (~3 m−1) is low enough to be used in a 50 mm diameter lamppost 2DPRCS. The reflection solar concentrator (RSC) is also proposed, which can be combined with multijunction Si solar cells for lamppost-type systems that utilize sunlight coming not only from the south side but also from the east and west sides. We believe that, in the near future, this new approach based on 2DPRCS can enable high-efficiency concentrated photovoltaic systems. [ABSTRACT FROM AUTHOR]

This work studied the wind load acting on a point focus solar furnace composed of a 110 m2 heliostat and a 77 m2 concentrator through wind tunnel testing. Based on wind tunnel test data under 305 different working conditions, the variation laws of the wind pressure coefficient, power spectral density, and wind load coefficient of the heliostat and concentrator were analyzed. The results showed that due to the interaction between the concentrator and heliostat, the wind speed near the heliostat and concentrator decreased but the turbulence intensity increased, which caused the peak wind load coefficient to rise slightly. The results suggested that a safety factor of 1.1–1.2 should be considered for structural design and optimization of solar furnaces.

The present experimental study aims to make advancements in the daily production of freshwater by a single solar still, with the ultimate goal of increasing its efficiency. The experiment was carried out in the solar still with and without integration at four different water masses within the basin, and metrics such as water, glass, basin temperature, and drinkable water generated were measured. The results showed that the daily distillate collected from the integrated system using 2.5 kg/h of mass flow in the parabolic concentrator produced 2.99 kg at the minimum water mass of 20 kg placed in the basin. When the flow velocity of water in the parabolic concentrator is raised from 2.5 to 5 kg/h, the amount of freshwater generated decreases from 2.99 to 2.66 kg. Compared to traditional single slope solar still, the potable water generated increases by roughly 18.24, 18.29, and 18.33% for water mass of 30, 40, and 50 kg, respectively, with the mass flow rate of water in the serpentine tubes as 2.5 kg/h. The results also reveals that, in addition to the PTC collector, the mass flowrate of fluid in the serpentine tube arrangement submerged in the basin affects daily solar efficiency. There is a significant reduction of about 1–2.3% in the daily efficiency of the system with increased mass flow rate of fluid in the serpentine tube arrangement. Similarly, the daily efficiency in all the cases reduces with increased water depth. [ABSTRACT FROM AUTHOR]

Due to population growth and technological advancements, the energy demands of countries are increasing every year. Consequently, research and development (R&D) studies in renewable energy have been on the rise in order to meet the growing energy demands. Wind energy is especially crucial in this regard. Wind turbines are capable of producing energy within the wind speed range of 5 m/s to 25 m/s, with a capacity factor of approximately 30–35%. In areas where wind speeds are insufficient, efforts are being made to improve turbine performance for energy production at low wind speeds. One of these studies involves incorporating the turbine into a concentrator to increase the wind speed and subsequently the capacity factor of the turbine for energy production at low wind speeds. In this study, the concentrator of the wind turbine with the SG 6043 blade section is taken into consideration, and the impact of synthetic jet application in the wind turbine concentrator is investigated. An optimization study is conducted to determine the parameters that will maximize the speed increase in the concentrator. The optimum parameters that lead to the maximum wind speed increase in the concentrator are as follows: the velocity of the synthetic jet is 140 m/s, the frequency of the synthetic jet is 58.89 Hz, the angle of the synthetic jet is 26.16º, the position of the synthetic jet is 0.675 m, and the angle of attack is 24.1º at a free wind speed of 5 m/s. The use of synthetic jet application in the wind turbine concentrator results in a 1.33 times increase in free wind speed. Consequently, the concentrator with synthetic jet application can be used in regions with poor wind speed statistics to generate energy from wind and increase the capacity factor of wind turbines. [ABSTRACT FROM AUTHOR]

Metamaterials are artificial materials that can achieve unusual properties through unique structures. In particular, their "invisibility" property has attracted enormous attention due to its little or negligible disturbance to the background field that avoids detection. This invisibility feature is not only useful for the optical field, but it is also important for any field manipulation that requires minimum disturbance to the background, such as the flow field manipulation inside the human body. There are several conventional invisible metamaterial designs: a cloak can isolate the influence between the internal and external fields, a concentrator can concentrate the external field to form an intensified internal field, and a rotator can rotate the internal field by a specific angle with respect to the external field. However, a multifunctional invisible device that can continuously tune across all these functions has never been realized due to its challenging requirements on material properties. Inside a porous medium flow, however, we overcome these challenges and realize such a multifunctional metamaterial. Our hydrodynamic device can manipulate both the magnitude and the direction of the internal flow and, at the same time, make negligible disturbance to the external flow. Thus, we integrate the functions of the cloak, concentrator, and rotator within one single hydrodynamic metamaterial, and such metamaterials may find potential applications in biomedical areas such as tissue engineering and drug release. [ABSTRACT FROM AUTHOR]

The results of testing for light resistance of polymeric materials are given: polyethylene pipe with a diameter of 110 mm; specialized fitting for installation and dismantling; polyethylene tape with a diameter of 22 mm and a wall thickness of 1 mm; and polyethylene geomembrane film. These products are designed for construction work, where they operate under the influence of solar radiation in open air for several years. In real conditions, they are under the influence of the surrounding atmosphere (snow, rain, wind, sunlight, etc.). The strength of polymeric materials is affected by the temperature and humidity of the environment, but in our study, we limited ourselves to studying the light resistance of polyethylene products to the effects of the flux of solar radiation. This study was carried out at the Institute of Materials Science, Uzbekistan Academy of Sciences, on the afocal plane of the Big Solar Furnace with a thermal power of 1000 kW. To perform this study, it was enough to operate 1 of the 62 heliostats of the Big Solar Furnace. In order to avoid overheating of the tested materials, we selected an appropriate heliostat and an afocal zone of the concentrator, where a uniform distribution of the density of weakly concentrated solar radiation is carried out. The necessary values of the density distribution of the concentrated solar radiation were obtained by defocusing the 31 (peripheral) heliostat of the Big Solar Furnace. A calculation estimate of the possible temperature heating of the samples according to the Stefan–Boltzmann formula was carried out. In the process of testing polymeric materials for light resistance, control and measurement of the temperature samples were carried out remotely by using an infrared camera (thermal imager). To assess the strength of polyethylene materials to light radiation, an analysis of crystalline structures was carried out before and after irradiation of the samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of Al-MOF scaffolds with high surface area and voluminous pores. • Al-MOF is uniformly decorated with pomegranate peel extract as a probe receptor. • Al-MOF-PPE sensor offers an exclusive selectivity for Cr(VI) sensing/reduction. • Al-MOF-PPE-Cr(III) material serves as a corrosion inhibitor for Al-air batteries. The growing presence of hexavalent chromium in environmental and industrial settings highlights the importance of developing an eco-benign platform for real-time in-situ sensing/screening and decontamination. This research presents a facile and portable solid-state optical sensor using waste Punica Granatum, i.e., pomegranate peel extract (PPE) adorn onto Aluminium-based Metal-Organic Frameworks (Al-MOFs) for the sensing of carcinogenic Cr(VI) and its decontamination to benign Cr(III). The sensor fabrication entails a hydrothermal synthesis to form Al-MOF scaffolds decorated with PPE through direct immobilization. Al-MOF exhibits a large surface area with well-defined pore channels that facilitate PPE's voluminous/uniform anchoring in restricted orientations to serve as an ion-selective probe for specifically targeting ultra-trace Cr(VI). The surface/structural morphology and porosity of the Al-MOF-PPE material are characterized using scanning/transmission electron microscopy and BET/BJH analysis. The reduction of Cr(VI) by the Al-MOF-PPE is validated by electron spectroscopy for chemical analysis, corroborated by a conspicuous color transition from light yellow to dark brown. The efficient reduction of Cr(VI) by Al-MOF-PPE is achieved at pH 2–3, in the linear response range of 0.3–300 ppb and a detection limit of 0.23 ppb for Cr(VI). The sensory system prefers minimal PPE probe content (4 mg) and sensor dosage (5 mg) for ion-sensing and decontamination studies, highlighting its remarkable operational efficacy. Post Cr(VI) reduction, electrochemical studies confirm the utility of Al-MOF-PPE-Cr(III) as a corrosion inhibitor for metal surfaces. Tafel plots demonstrate that Al-MOF-PPE-Cr(III) exhibits cathodic and anodic inhibition characteristics, ensuring excellent surface protection for aluminum electrodes upto 220 min in Al-air batteries. The proposed Al-MOF-PPE offers dual functionality as a naked-eye platform for Cr(VI) decontamination, and the Al-MOF-PPE-Cr(III) material is an excellent corrosion inhibitor for energy storage devices. [ABSTRACT FROM AUTHOR]

This paper presents a passive concentrator for single-phase inverters with a three-phase output, which uses magnetically coupled reactors. Due to the development of renewable energy systems, the proposed systems may enable the easier integration of converters in the form of inverters with the power system. Two variants of cooperation of the concentrator with single-phase voltage inverters were considered. The first variant proposed a system topology in which three single-phase full-bridge inverters were connected to the concentrator, while the other variant proposed six half-bridge inverters. A control system of the inverters that does not use PWM was developed. A common star point was created for the supply voltages in the form of a capacitive divider covering all the inverters. An analysis of the concentrator system was presented, taking into account the cooperation with inverters. The overall power of the TDSλ system was defined and the relationship for its determination was given. Simulation studies were described, presenting the obtained voltage and current waveforms. The impact of changing the supply voltage of the inverters on the operation of the concentrator and the shape of the output voltages was assessed. The proposed systems allow you to connect 3 or 6 single-phase inverters. The use of magnetically coupled reactors enables the use of a magnetic system of lower power and size. The described concentrators enable the generation of multi-level three-phase output voltage with a low THD content.

The present research work shows how a functional subsonic moist-air wind tunnel has been designed. Although this type of wind tunnel has never been developed to date, it is particularly interesting to develop a satisfactory design of feasibility under moist air conditions. Low-speed vertical-axis wind turbines employ different kinds of rotors, such as Savonius, Darrieus, and H-rotor. All these wind turbines present clear advantages, e.g., the horizontal-axis wind turbines are omnidirectional. This means they can work under different wind directions, need lower maintenance, and begin working under low wind speeds of 3 m/s. Recently, a new application of wind concentrators enabled the vertical-axis wind turbines to improve their performance coefficient based on new concepts like moist air phase change, which are being analysed to improve energy conversion. Thus, expectations were raised to design a suitable wind tunnel that accounts for the relative humidity of moist air. An initial prototype showed that the behaviour of open wind tunnels where the relative humidity of moist air was controlled by an adiabatic evaporative process was satisfactory. However, for such wind tunnels, certain improvements like computer control systems would need to be developed.

Solar energy is an inexhaustible renewable energy resource, which is a potential solution to global warming and aids sustainable development. The use of solar-thermal collectors to harness solar energy facilitates low-cost heat storage and can improve the stability of power grids based on renewable energy. In solar-thermal collectors, traditional concentrators, such as parabolic troughs and dishes, are typically used but inevitably require high-precise supports and complex tracking sun systems, which increase the cost of solar-thermal power stations and hinder their further applications. In contrast, planar meta-lenses (so-called metasurface-based concentrators) consisting of two-dimensional nanostructured arrays are allowed to engineer the frequency dispersion and angular dispersion of the incident light through delicately arranging the aperture phase distribution, thereby correcting their inherent aberrations. Accordingly, the novel meta-lenses offer tremendous potentials to effectively capture broadband, wide-angle sunlight without the extra tracking system. This review summarizes the research motivation, design principles, building materials, and large-area fabrication methods of meta-lens for solar energy harvesting in terms of focusing efficiency, operation bandwidth, and angular dependence. In addition, the main challenges and future goals are examined. [ABSTRACT FROM AUTHOR]

A combined solar phase-change thermal-storage heating system is proposed, wherein erythritol is used as the phase-change material (PCM) used to fill the thermal-storage device, and the storage cavity is heated and stored with a disc concentrator. The Solidification/Melting, Volume-of-Fluid (VOF) model of ANSYS Fluent software was used to simulate the phase-change process of erythritol inside the thermal-storage device. The thermal-storage device was designed based on our numerical calculations, and its performance was tested. We found that larger PCM-volume fractions correlated with lower PCM volume-expansion rates and longer total melting times during the heat storage process. When the φ value equaled 80%, the PCM solid–liquid-phase interface and temperature distribution were most uniform and showed the best heat storage. In addition, the size of the heat-storage device affected the heat-exchange area, and the total melting time of the PCM decreased and then increased as the width-to-height ratio (I) increased. With this design capacity, the late stage of the charging process of the heat-storage device accounted for 70% of the total time, and the heat energy-utilization rate during the boiling process was 66.3%. Overall, this combined heating system can be considered a very efficient solar energy-utilization terminal for basic domestic energy needs. [ABSTRACT FROM AUTHOR]

Assembled yurt has the characteristics of easy construction, convenient relocation and transportation, and can dynamically adapt to the changing climate of the grassland, actively adapt to the climate change, and more suitable for the modern grassland living environment, so it has become a residential type suitable for the grassland lifestyle. But the winter energy suppling of assembled yurts in cold regions mostly adopts biomass combustion and electric heating, which cannot meet the requirements of energy distributed utilization and green low-carbon sustainability. In order to solve the above problems, this paper proposes a novel solar multi-surface concentrated heating technology applied in solar assembled yurt energy suppling. It has several characteristics such as the solar thermal energy ‘relay’ transport, small heat transfer resistance, solar heating collection system integrated with enclosure of yurt and positive buoyancy gradient heat transfer. The technical operation principle and the structural curve of the multi-surface concentrator are introduced. The optical performance of the concentrator with time is analyzed with the optical simulation software TracePro. Under actual weather conditions, the effects of positive buoyancy gradient heat transfer and negative buoyancy gradient heat transfer on the thermal performance of the outlet temperature and heating collection in the concentrator are compared and studied. The results show that with the increase of the radial incidence angle, most of the incident and reflected light is received by the receiver, and less light escapes. When incidence angle is 0, the light receiving rate and concentrating efficiency of the concentrator are 95.00% and 76.96%, respectively. When the radial incidence increases to 15°, the light receiving rate and concentrating efficiency of the concentrator are 89.50% and 72.14%, respectively, and when the axial incidence angle increases to 30°, the light receiving rate and concentrating efficiency of the concentrator are 83.47% and 67.99%, respectively. In addition, the concentrating efficiency of adjacent concentrators with different orientations is superimposed at about 10:30 and 13:30, so these two moments can be used as three groups of concentrators start switching time, achieving energy supply of system stably and continuously. In winter sunny days, the outlet temperature of the concentrator with positive buoyancy gradient heat transfer and negative buoyancy gradient heat transfer has the same variation trend, which increases first and then decreases with the test time. However, due to the combined influence of the axial incidence angle and the heat transfer mode, the time of the concentrator with positive buoyancy gradient heat transfer and negative buoyancy gradient heat transfer to reach the maximum outlet temperature is inconsistent. The maximum outlet temperature and heating collection of the concentrator with positive buoyancy gradient heat transfer is about 21.3 ℃ and 787.29 W, which is 9.3℃ and 59.30% higher than that of the concentrator with positive buoyancy gradient heat transfer, and the total heating collection of the concentrator with positive buoyancy gradient heat transfer is about 5.46 MJ, 31.10% higher than that of the concentrator with negative buoyancy gradient heat transfer. In addition, the photothermal conversion efficiencies of the concentrator with positive buoyancy gradient heat transfer and negative buoyancy gradient heat transfer are 46.81% and 35.71%, respectively. This provides a reference for the matching of assembled yurt and energy supplying concentrator. [ABSTRACT FROM AUTHOR]

The application of compound parabolic concentrator (CPC) in photovoltaic/thermal (PV/T) system increases the thermal and electrical energy gain, and the phase change material (PCM) helps cool down the operating temperature of cells. In this study, an open-air experiment is constructed to compare the overall performance of conventional flat photovoltaic (FPV), concentrating photovoltaic/thermal (PV/T-CPC) and concentrating photovoltaic/thermal phase change (PV/T-CPCM) system. The maximum PV backplane temperature is 69.9 °C in PV/T-CPC, 59.2 °C in PV/T-CPCM and 36.7 °C in FPV system respectively, and the PV temperature distribution non-uniformity in PV/T-CPC is 1.5 times higher than that in PV/T-CPCM system, showing the application of concentrator enhances the useful thermal energy and meanwhile the PCM effectively improves the local overheating and temperature distribution non-uniformity problem. The average thermal energy and efficiency of PV/T-CPCM are over 2462.0 kJ and 9.0% higher than those of PV/T-CPC system respectively. Besides, the electrical power/total exergy of PV/T-CPCM system are over 1.3/4 and 1.6/2 times of FPV and PV/T-CPC system respectively. Results present that the PV/T-CPCM system owns superior thermal, electrical and exergy performance among the three systems, and the application of CPC and PCM has great advantages in improving the overall performance of the PV/T unit. [ABSTRACT FROM AUTHOR]

In this study, a thermodynamic model for concentrated semi-transparent-photovoltaic thermoelectric generator (CSPV-TEG) hybrid power generation system has been developed. Using the model, solar cell temperature, exergy and electrical efficiency of the hybrid system, temperature difference across TEG, power output and photovoltaic conversion efficiency of the PV module and the electrical efficiency of the TEG module have been calculated. The simulation of the system, using MATLAB, was conducted for clear day in May for New Delhi by varying the concentration ratio (C) and the number of p-n thermocouples (N). The results illustrate that for the hybrid system, maximum power output of 219.75 W was obtained for C = 2 N = 200 case and peak electrical efficiency of 10.44% was obtained for C = 1 N = 200 case. The peak value of the exergy efficiency of the hybrid system exceeded the peak value of electrical efficiency of the hybrid system by 1.33%.

The article describes technique for modelling of ultrasonic vibrations amplifiers, which are implemented in the form of non-uniform ring-shaped waveguides, based on application of harmonic balance method. Bending vibrations of the waveguide are described by means of non-uniform integral and differential equations equivalent to Euler–Bernoulli equations in order to simplify calculation of amplitude-frequency characteristics of vibrations, particularly, to exclude the need of working with singular matrices. Using harmonic balance method, equations of vibrations are reduced to overdetermined non-uniform linear system of algebraic equations, which least-squares solution is determined by means of pseudo-inverse matrix. On the basis of analysis of numerical example possibility of existence of variable-sign and constant-sign vibration modes of the waveguide is shown and it is determined that for realization of amplifying function it is necessary to use waveguide at constant-sign vibration mode. The constant-sign vibration modes are combinations of bending defor-mation and extensional deformation of central line of the waveguide and they are detected due to accounting extensibility of the central line in equations of vibrations. Validity of the obtained results is confirmed by comparing them to the results of modelling by means of finite element method.

To improve the concentration performance of the concentrator in the iron ore beneficiation process for iron ore tailings, a coupled simulation analysis of the concentration process was conducted using the discrete element software EDEM (Engineering Discrete Element Method) and the finite element FLUENT software. The volume concentration at the bottom flow outlet of the concentrator was used as the evaluation index. The scraper rotation speed, feed rate, and feed concentration were considered as parameters. Response surface experiments were designed using the Box-Behnken module in Design Expert11 software, and numerical simulations were performed to obtain data. Based on the numerical simulation results, a prediction model was established using the backpropagation neural network (backpropagation neural network, BP-NN) and combined with the genetic algorithm (genetic algorithm, GA) for parameter optimization of the thickener’s concentration conditions. The results showed that with a scraper rotation speed of 9.7677 rpm, feed rate of 0.2037 m/s, and feed concentration of 6.5268%, the maximum outlet volume concentration reached approximately 62.00%. The predicted optimal working conditions were validated through physical tests and numerical simulations. The average outlet volume concentration in the physical tests was 60.712% (n = 10) (“n” is the number of experiments), with an error of only 2.077% compared to the predicted value. The middle outlet volume concentration in the numerical simulation experiments was 59.951% (n = 10), with an error of only 3.304% from the expected value. These results demonstrate the feasibility of using a genetic neural network for optimizing the EDEM–FLUENT simulation parameters of the thickener, providing valuable insights for the matching optimization of the thickener’s process parameters.

Presented is a new cylindrical waveguide (WG) system based on a two-dimensional photoreceptor-conversion scheme (2DPRCS) for lamppost-type solar-cell systems. The optical properties of polydimethylsiloxane (PDMS) were evaluated as the WG material, and we found that the intrinsic optical loss of our PDMS-based waveguide (~3 m−1) is low enough to be used in a 50 mm diameter lamppost 2DPRCS. The reflection solar concentrator (RSC) is also proposed, which can be combined with multijunction Si solar cells for lamppost-type systems that utilize sunlight coming not only from the south side but also from the east and west sides. We believe that, in the near future, this new approach based on 2DPRCS can enable high-efficiency concentrated photovoltaic systems.

Manipulating transient mass transfer plays a crucial role in physics, chemistry, biology, and other fields. One typical example is chemical waves, whose concentration profiles have spatiotemporal variations. Based on a general model associated with the advection‐diffusion equation, an optimized transformation‐mass‐transfer theory is proposed to flexibly control transient mass transfer. As an example application, a class of separators is theoretically designed to achieve the separation of chemical waves. Meanwhile, three typical types of devices for cloaking, concentrating, and rotating chemical waves are proposed successfully, thus offering more versatile control methods. Such theoretical analysis is well confirmed by the computer simulations. These results provide insights into novel manipulation of chemical waves associated with biochemical reactions and promote potential applications for transient mass diffusion. [ABSTRACT FROM AUTHOR]

In this paper, it presents a detailed analysis of the use of the parabolic solar concentrator in heating and boiling water, as the parabolic solar concentrator was manufactured with a diameter of (96 cm), the focal length of the dish is (72 cm), and the focus depth of the dish is (8 cm). It was made using a parabolic dish with a diameter of (96 cm) and using glossy aluminum foil as a reflective sun ray after being cut into strips 10 cm wide and glued to the inner surface of the dish. Metal tin cans with two capacities (1L and 2L) were used as the absorbent receiver. Experiments were conducted to boil water from the roof of the house in Nassiriya city. The study calculated the optical efficiency of the equivalent solar concentrator, the amount of heat output as a result of the fall of concentrated solar radiation on the receiver, the amount of useful heat gained, the thermal losses from the receiver, the collector efficiency. Many tests were conducted in Nassiriya city weather conditions. The results of the experiments showed that the efficiency of the solar center mainly depends on the diameter of the concentrator dish, the quality of the reflector used, the time of heating the water, and the closing to midday. While the high ambient air velocity leads to a decrease in the receiver temperature by increasing the heat loses to ambient air by convection, thus reducing the efficiency of the solar concentrator; as well as the accuracy of directing the dish towards the sun and determining the focus accurately also affects the efficiency of the solar concentrator. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate a combination of two large Fresnel lenses and six segmented mirrors for concentrating sunlight efficiently within a common area throughout the day without mechanical tracking the sun. The proposed system was used for efficient solar thermal power generation, i.e., efficient heating of water. The angular position of two lenses is designed and mounted in such a way that the lenses are in direct line-of-sight with the sun for efficient sunlight collection during early morning, mid-day and for evening hours. Further, the height gap between Fresnel lenses and receiver unit is sufficient enough such that there is no shadow effect on the receiver unit hence the receiver unit is also exposed to direct sunlight rays throughout the day. Due to concentration of sunlight throughout the day the efficiency of solar thermal system is significantly enhanced. This is due to the fact that with the help of the proposed system, apart from concentrated sunlight made incident on to the solar thermal receiver it is also exposed to direct sunlight. The thermal receiver unit is placed in the common area and fluid is heated very fast. The design of system using ray optics in ZEMAX and experimental study of the direct and collected incident sunlight radiations using the proposed concentrating system on the receiver unit is analyzed. The thermal performance of the proposed system is compared with combination of single large Fresnel lens and segmented mirrors. The instantaneous thermal efficiency of the proposed system is around 20% or more in comparison to single lens concentrating system. The result shows that this type of system is highly efficient, and very much useful for countries where sunlight is available in plenty. Therefore, the proposed system is very much helpful for sustainable development of country. • Dual large Fresnel lens and segmented mirrors based efficient solar concentration system. • Non-mechanical tracking solar concentrator. • Collection of direct and concentrated sunlight rays on solar thermal collector unit. • Comparison of performance of dual lens and single lens optical concentration system for thermal energy. [ABSTRACT FROM AUTHOR]

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