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About one-third of world energy production is destined to the industrial sector, with process heat accounting for about 70% of this demand; almost half of this quota is required by endothermic processes operating at temperatures above 400 °C. Concentrated solar thermal technology, thanks to cost-effective high-temperature thermal energy storage solutions, can respond to the renewable thermal energy needs of the industrial sector, thus supporting the decarbonization of hard-to-abate processes. Particularly, parabolic trough technology using binary molten salts as heat transfer fluid and storage medium, operating up to 550 °C, could potentially supply a large part of the high-temperature process heat required by the industry. In this work, four industrial processes, representative of the Italian industrial context, that are well suited for integration with molten salt concentrators are presented and discussed, conceiving for each considered process a specific coupling solution with the solar plant, sizing the solar field and the thermal storage unit, and computing the cost of the process heat and its variation with the storage capacity. Considering cost data from the literature associated with the pre-COVID-19 era, an LCOH comprising the range 5–10 c€/kWhth was obtained for all the cases studied, while taking into account more updated cost data, the calculated LCOH varies from 7 to 13 c€/kWhth. [ABSTRACT FROM AUTHOR]

Volume Phase Gratings (VPG) are often recorded using holographic emulsions such as photopolymer, Dichromated Gelatin (DCG), and silver halide. We employed silver halide emulsion to record the VPG in monochromatic red wavelength for solar concentration purposes. According to the Braggs condition, the recorded VPG's diffraction efficiency reaches its peak at the recorded angle and wavelength. For solar applications, we needed high diffraction efficiency over a wide angle and wavelength range. So, we captured multiplexed single VPG in our own panchromatic silver halide emulsion. The procedure of making panchromatic silver halide emulsion is described in depth. This technique is unique in that it achieves peak diffraction efficiency at broad wavelength and wide angle in a single multiplexed VPG. The panchromatic multiplexed VPG produced a high diffraction efficiency in wide-angle response with overall visible wavelengths. This study describes the high diffraction efficiency multiplexed VPG in its own manufactured panchromatic silver halide emulsion for solar concentrating applications. [ABSTRACT FROM AUTHOR]

Increasing global economic development leads to a continuous increase in energy demand, considering the limited conventional resources of energy as well as the impact on the environment associated with its use. The primary disadvantage of solar energy is that it is only accessible during the day. Thermal energy storage systems can overlook this flaw since they can store energy throughout the day for use at night. This paper presents a new cooling technique for low-concentration parabolic collectors with microchannel and Phase Change Material (PCM). A test model consisting of a parabolic concentrator was designed and fabricated to test the parabolic concentrator with and without PCM in Baghdad city during January, March, and July. The solar receiver is an essential component of a solar-powered system and was manufactured from Aluminum metal with 44 microchannels (0.3 m in length, 0.02 m in width, and 0.009 m in height), where the receiver consisted of four rows of microchannels, each row consisting of 11 channels is constructed with velocity and temperature measurement facilities to achieve the experimental results. The results show that the PCM will store the energy roughly three hours after sunset at a flow rate of 0.009339 kg/s. Also, the result indicated that the two-axis tracking system would increase thermal efficiency.

The global challenge of sustainable and affordable wastewater treatment technology looms large as water pollution escalates steadily with the rapid pace of industrialization and population growth. The photocatalytic wastewater treatment is a cutting-edge and environmentally friendly technology that uses photons from light source to degrade and remove organic and inorganic contaminants from water. Thus, utilizing solar energy for photocatalytic wastewater treatment holds great promise as a renewable solution to alleviate pressures on the global water crisis. Employing solar concentrators to intensify sunlight for photocatalysis represents a promising avenue for future applications of a low-cost and rapid sustainable wastewater purification process. This groundbreaking approach will unveil fresh technological avenues for a cost-effective, sustainable, and swift wastewater purification process utilizing sunlight. This review article explores diverse solar concentrating systems and their potential applications in the wastewater treatment process. [ABSTRACT FROM AUTHOR]

Over the past few years, there has been a growing interest in renewable energy sources. Among them, photovoltaic (PV) technology is advancing rapidly. Solar insolation is the most crucial factor for PV installations. Various solutions, such as tracking mechanisms, hybrid systems, and new materials, can enhance the efficiency of PV systems. Concentrators focus solar light onto the surface of solar modules, increasing production of electricity. Implementing such solutions can reduce the number of silicon cells in installations, leading to a decrease in waste generated during production. Dye concentrators have a positive impact on the performance of silicon systems. A two-stage study on the effect of dye concentrator application on PV cell efficiency is carried out. In the first stage, specific types of dye concentrators are tested for their interaction with the silicon system. Tinted and luminescent acrylic glass (polymethyl methacrylate, PMMA) in yellow and red are used as dye concentrators. The experiment included multiple measurement calibrations, such as the temperature of the tested silicon cell and the intensity of illuminance. Results showed absolute increase of efficiency in solar cells ranging from 0.05% to 1.42%, depending on the type of concentrator used. The most significant improvements were observed with luminescent red PMMA, averaging at 1.21%. The potential of this concentrator was further explored in the second stage of the study, investigating the relationship between the surface involvement of the silicon cell and the dye concentrator. Test results indicated the potential of dye concentrators for integrating luminescent dye concentrator technology into PV systems. The effect of this integration is increase in the efficiency of the PV cell. On the other hand, it should be noted that replacing the PV cell with a dye concentrator reduces the efficiency of the entire photovoltaic system. Hence, the use of a PV cell and concentrator system is recommended especially for photovoltaic systems with a large area. As dye concentrators have the ability to operate without direct irradiance, they are also recommended for regions where natural light is dispersed. [ABSTRACT FROM AUTHOR]

The purpose of this article is to evaluate the performance of a prototype parabolic trough collector for three proposed scenarios, where geometric designs with optical characteristics are tested according to the appropriate technological paradigm; low cost of maintenance and implementation, intensive local labor, materials and resources of the implementation area. The device was developed by the Energy, Automation and Control Systems Research Group GISEAC of the Unidades Tecnológicas de Santander for low-cost water heating; using materials and labor for its fabrication easily available locally. Monte Carlo ray tracing methodology was applied using the open-access software SolTrace and Tonatiuh. To select the geometric scenario to be simulated, the edge angle and the width of the primary reflection system of the device were varied. The results obtained showed that the aperture of the parabola has a direct impact on the drop in the concentration ratio (CR) percentage value and the performance of the prototype. [ABSTRACT FROM AUTHOR]

Solar-thermal biomass conversion using both direct and indirect concentrated solar thermal energy is an emerging approach that combines two renewable energy sources to enhance energy efficiency and enable sustainable processing. This review paper provides a comprehensive examination of various types of solar concentrators and reactors, showcasing the diversity of available technologies and their roles in enhancing conversion efficiency. The paper focuses on the reported studies on biomass solar-thermal conversion through gasification and pyrolysis processes, critically discussing the integrated process operating conditions and the quality of the products (biofuels). These analyses affirm the technical viability, emphasizing the relatively low energy investment required for pyrolysis compared to the total energy output from biomass feedstock. This points to the substantial promise of solar thermal biomass conversion as a sustainable and efficient renewable energy solution. The conclusion highlights the importance of ongoing research, technological advancements, and policy support to fully realize the potential of solar-thermal conversion of biomass.

Concentrated solar power is a promising technique enabling renewable energy production with large scale solar power plants in the near future. Estimating quantitatively the reflectivity of a solar concentrator is a major issue, since it has a significant impact on the flux distribution formed at the solar receiver. Moreover, it is desirable that the mirrors can be measured during operation in order to evaluate environmental factors such as day/night thermal cycles or soiling and ageing effects at the reflective surfaces. For that purpose, a backward gazing method that was originally developed to measure mirror shape and misalignment error was developed. The method operates in quasi real-time without disturbing the heat production process. It was successfully tested at the Themis solar tower power plant in Targasonne, France. Its basic principle consists in acquiring four simultaneous images of a Sun-tracking heliostat, captured from different observation points located near the thermal receiver. The images are then processed with a minimization algorithm allowing the determination of the reflectance and slopes errors of the mirrors. In this communication, it is shown that the algorithm allows one to get quantitative reflectivity maps at the surface of the heliostat. The measurement is fully remote and is used to evaluate surface reflectivity that depends on optical coatings quality and soiling effects. Preliminary results obtained with a Themis heliostat are presented. They show that reflectivity measurements can be carried out within repeatability about ± 5% Peak-to-Valley (PTV) and 1% RMS. Ways to improving these numbers are discussed in the paper.

Over the past few years, there has been a growing interest in renewable energy sources. Among them, photovoltaic (PV) technology is advancing rapidly. Solar insolation is the most crucial factor for PV installations. Various solutions, such as tracking mechanisms, hybrid systems, and new materials, can enhance the efficiency of PV systems. Concentrators focus solar light onto the surface of solar modules, increasing production of electricity. Implementing such solutions can reduce the number of silicon cells in installations, leading to a decrease in waste generated during production. Dye concentrators have a positive impact on the performance of silicon systems. A two-stage study on the effect of dye concentrator application on PV cell efficiency is carried out. In the first stage, specific types of dye concentrators are tested for their interaction with the silicon system. Tinted and luminescent acrylic glass (polymethyl methacrylate, PMMA) in yellow and red are used as dye concentrators. The experiment included multiple measurement calibrations, such as the temperature of the tested silicon cell and the intensity of illuminance. Results showed absolute increase of efficiency in solar cells ranging from 0.05% to 1.42%, depending on the type of concentrator used. The most significant improvements were observed with luminescent red PMMA, averaging at 1.21%. The potential of this concentrator was further explored in the second stage of the study, investigating the relationship between the surface involvement of the silicon cell and the dye concentrator. Test results indicated the potential of dye concentrators for integrating luminescent dye concentrator technology into PV systems. The effect of this integration is increase in the efficiency of the PV cell. On the other hand, it should be noted that replacing the PV cell with a dye concentrator reduces the efficiency of the entire photovoltaic system. Hence, the use of a PV cell and concentrator system is recommended especially for photovoltaic systems with a large area. As dye concentrators have the ability to operate without direct irradiance, they are also recommended for regions where natural light is dispersed.

Today, concerns regarding global warming resulting from fossil fuel usage and the depletion of these resources have led individuals to consider alternative, clean energy sources. Renewable energies such as solar energy are non-polluting, inexhaustible resources, serving as an excellent alternative to fossil fuels. Solar concentrate sunlight, directing it towards the solar oven. Utilizing renewable energy for cooking not only saves time and money but also ensures safety and security. The aim of this research is to construct and assess a solar oven equipped with a point Fresnel lens. The evaluations were conducted over a three-day period in March 2023. The maximum total thermal efficiency obtained for heating the milk for three days with different radiation intensity, wind speed and ambient temperature tested was 45%, 72.7% and 90%, respectively. The findings indicated that the solar oven could raise the milk temperature to 80℃ within one hour. The maximum attainable performance of this system was 90%.

About one-third of world energy production is destined to the industrial sector, with process heat accounting for about 70% of this demand; almost half of this quota is required by endothermic processes operating at temperatures above 400 °C. Concentrated solar thermal technology, thanks to cost-effective high-temperature thermal energy storage solutions, can respond to the renewable thermal energy needs of the industrial sector, thus supporting the decarbonization of hard-to-abate processes. Particularly, parabolic trough technology using binary molten salts as heat transfer fluid and storage medium, operating up to 550 °C, could potentially supply a large part of the high-temperature process heat required by the industry. In this work, four industrial processes, representative of the Italian industrial context, that are well suited for integration with molten salt concentrators are presented and discussed, conceiving for each considered process a specific coupling solution with the solar plant, sizing the solar field and the thermal storage unit, and computing the cost of the process heat and its variation with the storage capacity. Considering cost data from the literature associated with the pre-COVID-19 era, an LCOH comprising the range 5–10 c€/kWhth was obtained for all the cases studied, while taking into account more updated cost data, the calculated LCOH varies from 7 to 13 c€/kWhth.

Today, concerns regarding global warming resulting from fossil fuel usage and the depletion of these resources have led individuals to consider alternative, clean energy sources. Renewable energies such as solar energy are non-polluting, inexhaustible resources, serving as an excellent alternative to fossil fuels. Solar concentrate sunlight, directing it towards the solar oven. Utilizing renewable energy for cooking not only saves time and money but also ensures safety and security. The aim of this research is to construct and assess a solar oven equipped with a point Fresnel lens. The evaluations were conducted over a three-day period in March 2023. The maximum total thermal efficiency obtained for heating the milk for three days with different radiation intensity, wind speed and ambient temperature tested was 45%, 72.7% and 90%, respectively. The findings indicated that the solar oven could raise the milk temperature to 80? within one hour. The maximum attainable performance of this system was 90%. [ABSTRACT FROM AUTHOR]

The global challenge of sustainable and affordable wastewater treatment technology looms large as water pollution escalates steadily with the rapid pace of industrialization and population growth. The photocatalytic wastewater treatment is a cutting-edge and environmentally friendly technology that uses photons from light source to degrade and remove organic and inorganic contaminants from water. Thus, utilizing solar energy for photocatalytic wastewater treatment holds great promise as a renewable solution to alleviate pressures on the global water crisis. Employing solar concentrators to intensify sunlight for photocatalysis represents a promising avenue for future applications of a low-cost and rapid sustainable wastewater purification process. This groundbreaking approach will unveil fresh technological avenues for a cost-effective, sustainable, and swift wastewater purification process utilizing sunlight. This review article explores diverse solar concentrating systems and their potential applications in the wastewater treatment process.

Concentrating photovoltaic (CPV) systems have emerged as a transformative technology that incorporates radiation concentrators into the photovoltaic system to enable radiation to be concentrated onto a receiver—the solar cells. Different concentrator configurations have different impacts on the performance of the solar photovoltaic system. This research work aims to analyze the impact of different concentrators, comparing and identifying the most efficient structures for capturing and concentrating solar energy. Aiming at a deep analysis and comparison among concentrators shapes, this research work presents a unique investigation and revision among different structures such as flat, triangular, LFR, and parabolic concentrators. Moreover, since, in the UV–visible–NIR region, metals’ reflectance varies with the incident wavelength, five metals were considered: aluminum, gold, platinum, copper, and silver. Additionally, the research focuses on studying the effects of parameters critical to the quality of the concentration on the power obtained and on the uniformity of the radiation distribution on the surface of the receiver, as well as on the number of solar rays that reach the receiver. The power on the receiver increases proportionally with the number of reflector concentrators in the system and their reflectance. For parabolic geometries, the optical efficiency is affected by the receiver’s shadow on the concentrator and, in the case of the LFR, by a non-ideal alignment of the reflectors in relation to the receiver. However, in parabolic concentrator geometries, uniformity is usually lower, since in these configurations, the radiation is focused on specific areas of the receiver, usually the central zone.

An integrated light pipe receiver and thermal energy storage (TES) architecture is proposed for solar process heat applications. Simulations demonstrate the benefits of increased heat transfer area to a low conductivity TES medium and reduced surface radiation losses. When compared against a baseline design with a hemispherical absorber, the integrated light pipe receiver enables up to a factor of three higher energy storage for distributed absorption relative to localized absorption at the top of the TES. For a lower thermal conductivity TES medium or baselining to a flat-top absorber, an increase in thermal energy storage up to a factor of five results.

Researchers from Université de Sherbrooke have developed a new generation of high efficiency Solar Microreactor to harvest the power of the sun for hydrogen production. This paper presents the architecture, the manufacturing and assembly of this highly integrated system that incorporates in a monolithic block the heat exchangers, catalytic bed and manifolds. Miniaturization of the system provides high heat and mass transfer capabilities and can easily be assembled into a matrix to cover the focal point of any Solar Concentrator. Performances of the Microreactor is first investigated in a laboratory using a high flux solar simulator to plot an efficiency map for a dry methane reforming test under different combinations of reagent mass flow and reaction temperatures. This map is then used as a benchmark for outside tests in order to evaluate the real-condition efficiency of such microreactor matrix. Outside tests were performed with the Université de Sherbrooke’s 100 kW SpaceWatt solar concentrator. It is estimated that the efficiency reaches up to 54 % for the matrix of reactor in real condition operation for an estimated heat flux of 520 kW/m2 compared to the measured value of 71% in laboratory conditions for a single reactor with a heat flux of 800 kW/m2.

To improve the output power of solar-pumped lasers, we propose a new configuration of solar disk laser. A rotating parabolic reflector acts as the primary concentrator with top and bottom radii of 1600 and 600 mm, respectively. The incident sunlight is reflected by the primary concentrator to the inlet of the heteromorphic compound parabolic concentrator (HCPC) and is absorbed by the gain medium after multiple reflection. The diameter, thickness, and doping concentration of the Nd :YAG disk are 20 mm, 1 mm, and 1.0 at.%, respectively. The two surfaces of the disk are cooled by heavy water. Owing to the increased surface area of the disk for receiving sunlight, solar absorption by the gain medium is greatly improved. Ray tracing shows that maximum absorbed solar power by the Nd :YAG disk can reach 446 W through optimizing the HCPC. Solving rate equations, we obtain the laser output power in the TEM00 mode as high as ∼123 W, with a conversion efficiency of ∼27%. In addition, we analyze the temperature distribution of the solar-pumped Nd :YAG disk laser. The design of this solar concentrating system and the over-hundred-watts disk laser provides a new idea for further scaling the output power of solar-pumped solid-state lasers. [ABSTRACT FROM AUTHOR]

Solar concentration is the ability to harness solar radiation in order to increase the temperature of a receiver. The receiver is a component into which a heat transfer fluid can flow in an ORC system, which produces electricity, or it can be used for high-temperature thermal storage or even to implement thermochemical cycles. The choice of material is critical to ensure optimal performance and long-lasting operation. It is also essential that such material can operate at high temperatures and high thermal gradients. In short, material identification involves high thermal stresses that result in structural deformation. Different metal alloys were used to verify that the yield strength limit was not exceeded due to thermal stress induced by concentrated solar radiation. Starting with the general heat equation, the problem was implemented in Matlab. The purpose was to test whether thermal stress exceeds the yield strength, which is the condition in which elastic bonds in the material are changed, causing deformation. This condition, if exceeded, is sufficient to discard the material; otherwise, it is a necessary but not sufficient condition to resist over time. The best material identified was Inconel 740H, which had a high yield strength value and the lowest temperature difference. Under extreme working conditions, it withstood induced thermal shocks. [ABSTRACT FROM AUTHOR]

Due to decrease of oil reserves, the international commitment for the reduction of pollutant emissions and environmental protection, renewable energy sources are intensively studied, including solar energy applications. However, solar energy is not constant and one possible alternative are solar hybrid thermosolar power plants. A hybrid solar gas turbine has three subsystems: a solar concentrator with heliostat field and central tower receiver, a combustion chamber, and a regenerative gas turbine. A previous thermodynamic analysis allowed shows an energy and exergy study of the plant, from a thermodynamic model of the system that has a method of solar resource estimation. However, this analysis did not allow evaluation of the energy losses in the system components, although the original model considered the typical irreversibilities of these cycles. This work aimed to develop a thermodynamic model that estimates the energy losses in the subsystems and the solar hybrid gas turbine components from a few parameters. The model estimated the energy losses for a Brayton cycle hybrid solar thermal plant throughout the day July 20 in Barranquilla, Colombia. A Dymola compiler in Modelica language was used to evaluate the model, which facilitates the estimation of the results at different times of the day. In this case, the computations were performed hourly throughout the day. In the results, energy losses were 16 % in the solar concentrator when the solar resource was the maximum at noon and close to 1 % in the combustion chamber. Therefore, the hybrid solar Brayton cycle system is technically feasible and reduces fuel consumption. Consequently, it is important to continue developing concentration systems and reduce their energy losses. [ABSTRACT FROM AUTHOR]

This study presents a solar-powered parabolic dish desalination system with a solar tracking system and conical receiver. It efficiently transforms solar radiation into heat and evaporates saltwater, producing fresh water. The system is sustainable and affordable, making it a viable solution for water desalination in areas with limited access to fresh water. It achieves a high conversion rate from saltwater to fresh water, while consuming minimal energy. The results indicate that the system effectively utilizes solar energy, exhibiting high efficiency levels ranging from 78.56% to 82.77%, with an average efficiency of 80.79%. This system offers an effective solution to meet the growing demand for fresh water in water-scarce regions.

Polymers have become a major pollutant worldwide because their excessive use and poor disposal handling. Therefore, a system with selective solar concentration is proposed to solve this problem. This system is composed of a solar concentrator and a filter with upconversion nanoparticles made of rare earths. These materials can be obtained by the co-precipitation method. The materials are designed with a matrix of NaYF4 codoped by Yb3+ and Tm3+ so the upconversion process is carried out. This phenomenon helps to take advantage of the infrared radiation of the sun rays, converting it into UV radiation to improve the degradation efficiency in the solar concentrator system. The high density of the UV radiation concentrated on the polymer surface should promote a super accelerated degradation since the UV frequency is capable to break-down polymeric chains. It is expected that this strategy would be a sustainable option to reduce the impact of the polymeric waste. [ABSTRACT FROM AUTHOR]

Experimental investigation is performed to evaluate the thermal performance of a parabolic reflector concentrator using water as heat transfer medium. Experiments are performed on 16 m2 paraboloidal solar dish reflector concentrated with a biaxial solar monitoring system. Readings are taken for a period of 25 days between 10.00am to 3.00pm. The variation in the sun intensity (Ibn) was order of 550 to 1000 W/m2 during the experimentation. Radiation intensity was measured by using ASTM standards. The calculated system efficiency is a function of solar radiation, pressure, temperature and heat transfer to the circulating fluid. The optical efficiency is kept constant as 85%. The result shows that the thermal performance of the system is maximum (50.68%) at temperature 154.7oC and incident beam radiation of 666 W/m2. Heat loss calculations were performed to analyse the effect of conductive, convective and radiative heat losses. It was observed that convection is the dominant mode of heat loss affecting the thermal efficiency significantly. Uncertainty analysis is performed to predict the uncertainty in the results. The overall uncertainty is 0.75%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Computational Systems & ICTs is the property of ECORFAN-Mexico S.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the large carbon emissions of facility agricultural heating in severe cold regions in winter, a compound parabolic concentrator based soil heating system was presented. The system integrated with novel trough compound parabolic concentrator and was used for soil heating in facility agriculture. Following the structure of the compound parabolic concentrator, TracePro software was selected to trace the light in the compound parabolic concentrator. The variation trend of the light escape rate of the compound parabolic concentrator with the different incident angles was analyzed. Based on the calculation results, the performance of the solar collector system was investigated, and the impact of circulating air velocity on the photo-thermal performance of the solar collector system was explored. Research results indicate that when the circulating air velocity is 1.4 m/s and the average ambient temperature is about 28.9 °C, the temperature of the system outlet is up to 90.9 °C. The average instantaneous heat collection, maximum photo-thermal conversion efficiency, and unit area heat collection of the system are 740.6 W, 27.83%, and 0.8 MJ/m², respectively. This research can effectively promote the efficient integration of the solar collector system in facility agriculture. [ABSTRACT FROM AUTHOR]

Daylighting plays an important role in decreasing power usage in office buildings and enhancing indoor environments. Reducing the use of energy and producing energy from renewable sources will result in lower greenhouse gas emissions. Daylighting is a method of providing light indoors through the use of windows, solar panels, optical fibers, parabolic mirrors and other forms of daylight technologies. The proposed fiber optic daylighting system will illuminate the light uniformly in interior space. Parabolic mirror and Frensnel lens are two different efficient approaches available for fiber-based day lighting system. Captured light is passed via concentrator, fiber and lenses. Uniform lighting at the capture point eliminates the heat problem when incorporating optical plastic fiber is critical in making the device cost-effective. Collimated light increases device performance helping to inject full light into the optical fibres. From simulation setup will verify that uniform intensity of light will be illuminated to different regions of buildings by the fiber optic bundle. Collimated lighting and reduction of shadows caused by mechanical parts and the convex reflector will enhances the system's efficiency. Uniform illumination will be given at all time by using hybrid system. Using solar day lighting in homes and offices via optical fibre cables is a potential way to reduce the energy used for artificial lighting while also improving visual comfort and human health. Analysis and discussion have been conducted on the impact of optical fibre diameter on the brightness and homogeneity of light. This efficient technology can lower energy costs and also helps in climate change challenges. [ABSTRACT FROM AUTHOR]

This paper presents studies of the optical-energy characteristics of a parabolic solar collector for production of thermal energy for heating a building. The results of calculations, three-dimensional and topological distribution of energy in the focal zone of a solar concentrator with a diameter of 6.36 m installed at the Institute of Materials Science, Academy of Sciences of the Republic of Uzbekistan are presented. A mathematical model of the thermal regime of a solar concentrator is proposed, calculations are carried out to determine the operating temperature and the efficiency of the receiver. For efficient conversion of concentrated solar radiation, a receiver was developed from a solid copper pipe with a diameter of 12 mm in the form of a single cylindrical spiral. The outlet diameter of such a receiver was D = 200 mm. To reduce the loss from the outside, the receiver is covered with asbestos material and cement with a thickness of 20 mm. The degree of geometric concentration of the solar concentrator is 2126; the power is 18.03 kW at 800 W/m2 of solar radiation. Calculations show that the average daily thermal efficiency of the concentrator across the seasons of the year remains high (over 25%), and the system can also be operated for heating buildings. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to fabricating a low-cost solar parabolic dish concentrator with one-meter-long glass/silver mirrors on the reflecting surface. The concentrator's parabola curve is made of four layers of fiberglass needle felt and polyester resin. The parabolic dish surface is mirrored vertically with 2 mm thickness glass/silver mirrors with a width of 5 cm and a length of one meter attached with silicone glue. The system is assembled and tested at the Sharif University of Technology in Tehran, Iran. Energy and exergy efficiencies are calculated using cylindrical water heater receiver data. These data are used to calculate the receiver's absorbed energy and losses. Test results show that the major energy loss is due to convection. The average energy efficiency and the maximum exergy efficiency of the concentrator are 57% and 67%, respectively. The maximum power absorbed by the water is 1656.8 W at midday, and the maximum temperature observed on the receiver is 540 °C. Finally, a discussion is held to propose ideas to improve the fabrication process of the designed parabolic dish concentrator. This type of fabrication is suitable for regular thermal applications. However, several deficiencies are detected, and a few solutions are suggested. Mirror edges and flexibility are two of the parabolic dish's major defects. [ABSTRACT FROM AUTHOR]

Analytical and empirical models analyze complex and non-linear interactions between the input–output parameters of the system. This is very important in the case of photovoltaic systems to understand their real performance potential. On the other hand, manufacturers of photovoltaic panels rate the maximum performance of the system under fixed lab conditions as per standard testing conditions (STCs) or nominal operating cell temperature (NOCT) standards of IEC. These ratings do not provide the actual production potential of the system in a field with fluctuating conditions of irradiance and temperature. For the case of a concentrated photovoltaic (CPV) system, utilizing multi-junction solar cells (MJCs), there is no commercial tool available to analyze the performance and production, despite some recent empirical models that also require post-processing of experimental data to be used in conventional models. In this study, an artificial neural network (ANN)-based performance model is presented for a multi-junction solar cell, which is not only convenient to apply but can also be easily expanded to predict the real-field performance of the CPV system of any designed size. In addition, the ANN-based model showed a high accuracy of 99.9% in predicting the performance output of MJCs as compared to diode-based empirical models available in the literature. The irradiance concentration at the cell area and the cell temperature are taken as inputs for the neural network. If both of these parameters are known, then the cell efficiency as an output can accurately predict the CPV performance for a field operation.

Static solar devices have advantages over solar tracking systems. In pure reflective systems, solar reception is limited by the entry angle of the reflector. Many reflective systems are based on mirror Compound Parabolic Concentrators. The solar collection can be improved by placing a lens on top of the reflector. In this work, a static system is proposed, consisting of a mirror funnel concentrator with a prism on top. The system is designed using ray-tracing software and is subsequently built and experimentally evaluated. The system designed for an effective concentration factor of 4× reaches an effective concentration of 3.2× at 11:30 a.m. and has an acceptance angle of 60°. Considering the time interval from 8 a.m. to 4 p.m., the system harvests 30.7% more energy than the flat surface. If the time interval considered is from 9:30 a.m. to 2:30 p.m., the increase in harvest is ∼77%. The incorporation of the prism represents an increase of ∼6% compared to the bare reflective system. [ABSTRACT FROM AUTHOR]

• Newly identified high-concentration linear solar concentrator configurations. • Analytic evaluation of all optical losses for linear dual-mirror aplanats. • Superior intercept factors and concentration compared to prior studies. • Rapid capability for optical evaluations and hence ascertaining optimal designs. • Practical high-performance optics. Linear Aplanatic Fresnel Reflectors (LAFRs) were recently presented as a novel and viable dual-mirror solar concentrator. Within a vast parameter space, a few promising designs were identified and evaluated via raytracing. This cumbersome, time-intensive exploration left unresolved whether configurations with superior optical performance remained undiscovered. Here, we present analytic methods for all inherent optical losses for the LAFR - results that are equally valid for almost all sources of optical loss in all linear Fresnel reflector solar concentrators. The loss modes include the separate contributions linked to the transverse and longitudinal projected incidence angles. This permits exact rapid comparisons among the wide range of possible aplanatic designs in a physically transparent manner that quantifies each mode of optical loss. These analytic derivations subsume blocking of rays reflected from the primary mirror segments, radiation that misses the primary and strikes the ground, shading of the primary by the secondary, end losses, and rays reflected from the primary that either miss the secondary (spillage) or enter it and miss the absorber tube (ray rejection). LAFR designs superior to those determined previously, in terms of higher intercept factor and higher concentration, are found and evaluated. [ABSTRACT FROM AUTHOR]

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The continuous growth in energy demand requires researchers to find new solutions to enlarge and diversify the possible ways of exploiting renewable energy sources. Our idea is the development of a solar concentrator based on trapping the luminous radiation with a smart window. This system is able to direct light towards the photovoltaic cells placed on window borders and produce electricity, without any movable part and without changing its transparency. Herein, we report a detailed study of cellulose ethers, a class of materials of natural origin capable of changing their state, from transparent aqueous solution to scattering hydrogel, in response to a temperature change. Cellulose thermotropism can be used to produce a scattering spot in a window filled with the thermotropic fluid to create a new kind of self-tracking solar concentrator. We demonstrate that the properties of the thermotropic fluid can be finely tuned by selecting the cellulose functionalization, the co-dissolved salt, and by regulating their dosage. Lastly, the results of our investigation are tested in a proof-of-concept demonstration of solar concentration achieved by thermotropism-based light trapping. [ABSTRACT FROM AUTHOR]

Efficient management of solar radiation through architectural glazing is a key strategy for achieving a comfortable indoor environment with minimum energy consumption. Conventional glazing consisting of a single or multiple glass pane(s) exhibits high visible light transmittance and solar heat gain coefficient, which can be a double-edged sword, i.e., it allows sufficient sunlight to enter the building interior space for passive heating and lighting; on the other hand, it can cause glare discomfort and large cooling energy consumption. Among the various advanced glazing technologies being developed, Building Integrated Photovoltaic (BIPV) glazing has a prominent position due to its ability to reduce cooling load and visual discomfort while simultaneously generating electricity from sunlight. Recent years have witnessed remarkable advances in low-concentration optics such as Dielectric based Compound Parabolic Concentrators (DiCPCs), with a growing interest in the development of Building Integrated Concentrating Photovoltaic (BICPV) glazing to improve light harvesting and electric power output. One of the challenges faced by traditional BIPV glazing systems is the lack of dynamic control over daylight and solar heat transmission to cope with variations in weather conditions and seasonal heating/cooling demands of buildings. A promising solution is to integrate an optically switchable smart material into a BIPV glazing system, which enables dynamic daylighting control in addition to solar power conversion. Thermotropic (TT) hydrogel materials such as poly(N-isopropylacrylamide) (PNIPAm) and Hydroxypropyl Cellulose (HPC) are potential candidates for hybrid BIPV smart glazing applications, due to their unique features such as high visible transparency (in the clear state), strong light-scattering capability (in the translucent state) and large solar energy modulation. This paper reviews various types of electricity-generating glazing technologies including BIPV glazing and BICPV glazing, as well as smart glazing technologies with a particular focus on TT hydrogel integrated glazing. The characteristics, benefits and limitations of hybrid BIPV smart glazing are also evaluated. Finally, the challenges and research opportunities in this emerging field are discussed. [ABSTRACT FROM AUTHOR]

Solar-thermal biomass conversion using both direct and indirect concentrated solar thermal energy is an emerging approach that combines two renewable energy sources to enhance energy efficiency and enable sustainable processing. This review paper provides a comprehensive examination of various types of solar concentrators and reactors, showcasing the diversity of available technologies and their roles in enhancing conversion efficiency. The paper focuses on the reported studies on biomass solar-thermal conversion through gasification and pyrolysis processes, critically discussing the integrated process operating conditions and the quality of the products (biofuels). These analyses affirm the technical viability, emphasizing the relatively low energy investment required for pyrolysis compared to the total energy output from biomass feedstock. This points to the substantial promise of solar thermal biomass conversion as a sustainable and efficient renewable energy solution. The conclusion highlights the importance of ongoing research, technological advancements, and policy support to fully realize the potential of solar-thermal conversion of biomass. [Display omitted] • The use of solar-thermal energy for biomass conversion is thoroughly reviewed. • Solar concentrators, reactors and state-of-the-art technologies are discussed. • The potential of large-scale implementation of solar-thermal pyrolysis is discussed. • Latest studies on integrated solar-thermal pyrolysis and gasification are reviewed. • Solar-thermal biomass holds high potential as a sustainable energy solution. [ABSTRACT FROM AUTHOR]

Solar concentration is the ability to harness solar radiation in order to increase the temperature of a receiver. The receiver is a component into which a heat transfer fluid can flow in an ORC system, which produces electricity, or it can be used for high-temperature thermal storage or even to implement thermochemical cycles. The choice of material is critical to ensure optimal performance and long-lasting operation. It is also essential that such material can operate at high temperatures and high thermal gradients. In short, material identification involves high thermal stresses that result in structural deformation. Different metal alloys were used to verify that the yield strength limit was not exceeded due to thermal stress induced by concentrated solar radiation. Starting with the general heat equation, the problem was implemented in Matlab. The purpose was to test whether thermal stress exceeds the yield strength, which is the condition in which elastic bonds in the material are changed, causing deformation. This condition, if exceeded, is sufficient to discard the material; otherwise, it is a necessary but not sufficient condition to resist over time. The best material identified was Inconel 740H, which had a high yield strength value and the lowest temperature difference. Under extreme working conditions, it withstood induced thermal shocks.

In recent years, the technology of waveguide-based planar solar concentrators has been getting more attention in the Concentrated Photovoltaics (CPV) sector due to its compact design and performance versatility and its extended potential applicability from large power plants to built environments, such as Building Integrated Photovoltaics (BIPV). Within the last two decades, geometric design-based Planar Light Concentrator (PLC) and diffraction grating-based PLC have been developed with versatile design architectures along with luminescent PLC, which relies primarily on the development of concerned luminescent optical materials. However, congregating and evaluating the technical advancement gained in the field seems challenging due to the segregated state-of-the-art approaches. Hence, this review attempted to organise the present state of waveguide-based PLC in the frame of reference of PLC optics and optical material design. A systematic comparison of optics and optical material design parameters and the merit of the different PLC systems have been explored within this review to serve as a ready reference for its adoption to develop compact planar waveguide-based CPV systems.

The present research aims at promoting the stability and applicability of a hybrid daylighting system combining daylight and artificial light, which eventually enables a constant and pleasant luminous flux of the mixed light delivered by a terminal device installed indoors. That is, the present system allows a constant amount of luminous flux through its terminal device similar to an electric lamp, demonstrating its energy efficiency as well as comfortableness. The system effectively combines two different types of light, as solar rays are collected by a solar tracking sun light collector. The mixed light is transmitted indoors by optical fiber cables all the way to terminal devices installed indoors and discharged as needed. This feature enables the utilization of daylight to its full capacity, promoting solar availability. In this study, the photometry of hybrid lighting was experimentally measured and analyzed by using a spectrometer for different portions of sunlight when maintaining a constant luminous flux of mixed light. The effectiveness of hybrid lighting was explored for a number of cases in actual conditions, and the system was capable of delivering a constant illuminance of 1200 lux on a plane located 1.1 m away from the terminal device (light emitter). Finally, the system was installed in a test cell to verify its effectiveness for indoor illumination. [ABSTRACT FROM AUTHOR]

• Concentration ratio formula for a circular concentrator with flat receiver is presented. • Development reveals existence of two concentration ratio regimes. • One regime relies on the caustics while the other relies on the rays from the rim. • The circle can match the concentration of the parabola for large acceptance angles. We present a simple analytical formula for the geometric concentration ratio of a circular trough optical concentrator coupled to a flat (planar) receiver. The receiver is sized to achieve full collection (no spillage) for any combination of acceptance and rim angle. The development reveals the existence of two concentration ratio regimes, one controlled by the edge ray caustics, and the other controlled by the intersection of the edge rays from the rim alone. Notably, we show that in the latter rim ray regime, the circular trough achieves the exact same geometric concentration ratio as a parabolic trough. The provided formula fills a gap towards the development of a complete catalogue of concentration ratio formulas for different concentrator/receiver geometries. [ABSTRACT FROM AUTHOR]

The parabolic trough collector provides an extensive range of solar heating and electricity production applications in solar power plants. The receiver tube of the parabolic trough collector has a vital role in enhancing its performance by using different inserts inside it. In the present work, outdoor experimental tests were conducted to study the performance of a small-scale parabolic trough collector equipped with a centrally placed rotating helical shaft. Three cases were studied: a parabolic trough collector without helical shaft insert, a parabolic trough collector with stationary helical shaft insert, and a parabolic trough collector with a rotating helical shaft insert. The experiments are performed for different shaft rotational speeds (4, 11, and 21 RPM) and various flow rates (0.5, 1, 1.5, 2, and 2.5 LPM) of water as a heat transfer fluid. The fluid flow and heat transfer parameters (friction factor, Reynolds number, Nusselt number, and thermal enhancement factor) and performance parameters (thermal, overall, and exergetic efficiencies) are studied. The results indicated that the helical shaft insert had increased the required pumping power for the same flow rate. However, the parabolic trough collector thermal performance has enhanced with the shaft rotational speed. For all cases, the parabolic trough collector efficiency increases with the flow rate of the heat transfer fluid, but the percentage enhancement in efficiency decreases. Using a shaft rotational speed of 21 RPM and heat transfer fluid flow rates of 0.5 LPM leads to maximum thermal efficiency enhancement and a maximum friction factor ratio of 46.47% and 7.7 times, respectively, compared to plain tube. A comparison based on the same pumping power (thermal enhancement factor) shows that the maximum enhancement occurs at a flow rate of 1 LPM, and the efficiency enhancement is about 37% at a shaft rotational speed of 21 RPM. From an economic point of view, using a rotating helical shaft produces the lower annual cost of useful heat per kWh. [ABSTRACT FROM AUTHOR]

Imaging concentrators like the parabolic trough solar concentrators have been widely employed for energy production in solar power plants. The conventional imaging solar concentrators form a non-uniform Gaussian distribution on receiving absorbers yielding the highest temperatures. The traditional CSP system normally truncated a peripheral region of heat flux to better use the central part. CPV/T systems using the waste heat recovery method can largely improve the total efficiency. However, for the CPV module, the coolant temperature was usually below 80 °C, which limited the applications of the thermal cycle such as the ORC system. In this article, a novel trough-type free-form secondary solar concentrator (TFSC) for PV/Thermal hybrid application has been proposed. Different from other CPV/T concepts using a combined PV panel and cooling tunnel/tube, the current concept separates the receiver in two parts. The secondary free-form reflector is generated by the geometric construction method, resulting in uniform heat flux in the edge region and high concentration in the central region. Through the ray tracing method, the optical properties have been verified. Sensitivity analysis of the concentrating structure is also conducted. The results provide supports for the design and applications of novel CPV/T systems. [ABSTRACT FROM AUTHOR]

Solar concentrator collectors have the potential of meeting the medium- and high-temperature thermal energy demands of the world. A heat transfer fluid (HTF) is a vital component of a concentrating system to transfer and store thermal energy. This paper presents the design development of a solar paraboloidal dish concentrator (SPDC) and a study of selected HTFs using the storage receiver system of the concentrator. The locally designed SPDC (diameter 1.21 m and height 0.20 m) has features like light weight, effortless tracking, convenient transportation along with high optical and thermal performance. Three HTFs, silicone oil (SO), engine oil (EO) and ethylene glycol (EG), are selected based on their favorable properties for medium temperature (150–300 °C) applications. The characteristic parameters of HTFs, heating rate (Rh), instant thermal efficiency (ηith) and the overall heat loss coefficient (UL), are illustrated and determined experimentally. A new characteristic parameter, the normalized maximum fluid temperature (Tnf), is also introduced in the paper. In the heating test, the maximum attained temperatures by fluids, SO, EO and EG are found to be 240 °C, 180 °C and 160 °C, respectively. The thermal efficiencies of SO, EO and EG are determined to be 45, 36 and 31%, respectively. The heating rate of 6.56 °C/s is found to be the maximum for SO. Through the cooling test, the overall heat loss coefficient (UL) is computed to be 14 W/mK, which is the least among the three fluids compared. The high thermal performance, environmental safety and chemical stability of silicone oil make it suitable for use in concentrators for medium-temperature heat transfer and storage applications. [ABSTRACT FROM AUTHOR]

One of the modern methods for enhancing the efficiency of photovoltaic (PV) systems is implementing a solar tracking mechanism in order to redirect PV modules toward the sun throughout the day. However, the use of solar trackers increases the system's electrical consumption, hindering its net generated energy. In this study, a novel self-tracking solar-driven PV system is proposed. The smart solar-driven thermomechanical actuator takes advantage of a solar heat collector (SHC) device, in the form of a parabolic trough solar concentrator (PTC), and smart shape memory alloy (SMA) to produce effective mechanical energy for solar tracking applications from sun rays. Furthermore, a thermal–optical analysis is presented to evaluate the performance of the solar concentrator for the simulated weather condition of Dammam City, Saudi Arabia. The numerical results of the thermal and optical analyses show the promising feasibility of the proposed system in which SMA springs with an activation temperature between 31.09 °C and 45.15 °C can be utilized for the self-tracking operations. The work presented adds to the body of knowledge an advanced SMA-based SHC device for solar-based self-actuation systems, which enables further expansions within modern and advanced solar thermal applications. [ABSTRACT FROM AUTHOR]