Search

In this research, thermal modeling has been done to investigate the effect of nanofluid on the performance of the linear parabolic collector. Therminol vapor/liquid phase fluid (VP-1) has been used as a base fluid; iron oxide nanoparticles have been used to produce mono-nanofluid; and iron oxide multi-walled carbon nanotubes nanocomposite has been used as nanoparticles to produce hybrid nanofluid. The fluid flow inside the absorber tube of the collector is assumed to be turbulent. The results show that when hybrid nanofluid and mono-nanofluid are used, the energy and exergy efficiencies of the collector are higher than those for the conditions of using the base fluid, but their amount is slightly lower with the use of hybrid nanofluid than when the working fluid is mono-nanofluid. According to the obtained results, the highest energy efficiency of the linear parabolic collector using nanofluid and mono-nanofluid is 70.2% and 70.4%, respectively, and the highest exergy efficiency is 35.7% and 35.9%, respectively. Despite this, the friction coefficient of mono-nanofluid compared to hybrid nanofluid was obtained on average about 9% higher. The results showed that the criterion for evaluating the performance of the collector (hydrodynamic thermal efficiency) when hybrid nanofluid is used is more than when mono-nanofluid is used. [ABSTRACT FROM AUTHOR]

The present study investigates the viability of employing Solar parabolic trough collectors (PTC) and parabolic dish collectors (PDC) integrated with thermal energy storage (TES) as the primary heat source for a steam-powered Rankine cycle, aimed to produce 5500 kW power for green hydrogen generation. A techno-economic analysis finds the system's overall efficiency (solar input to generator output) as 15.06% with PTC and 18.80% with PDC. Besides, incorporating PTC with binary and ternary salts in the proposed system yields approximately 22.7 % lower capital costs and a 7.8 % shorter payback period than solar PDC. Likewise, the levelized hydrogen cost with these options is around 12.3 % lower than those of PDC across all zones. However, to sustain a maximum annual hydrogen production of 238.38 tonne, equivalent to an annual electricity generation of 11180.07 MWh in each zone, the required PTC area is approximately 24.85% larger than PDC area. • Concentrated Solar Power (CSP) technologies with TES systems are utilized for hydrogen production. • System's overall efficiency (solar to electric) is found to be 14.68 % with PTC and 18.33% with PDC. • The economic analysis compares the system's capital cost, payback period, and the levelized cost hydrogen production. • Month-wise hydrogen production is presented in the different Indian climatic zones. [ABSTRACT FROM AUTHOR]

The demand for efficient applications of solar energy and nanomaterials has grown significantly in recent years due to industrial needs and the desire to minimize energy consumption and costs. However, the efficiency of photovoltaic cells and solar-powered ships is highly dependent on solar radiation. In this study, a model for the installation of a parabolic trough surface collector (PTSC) was developed to achieve high temperatures on solar-powered ships. The current study analyzed the thermal characterization function in solar-powered ships under the effect of heat radiation, magnetic field, and viscous dissipation by employing hybrid magnetite particles (Fe3O4) and silver (Ag). The Cattaneo–Christov model has been used to assess heat flux in the thermal boundary layer. The Galerkin weighted residual method (GWRM) has been employed to solve the ordinary differential equations using MATHEMATICA 11.3 software. The findings showed that the thermal efficiency of the hybrid nanofluid was significantly enhanced by 56.3% relative percentage. The motto of the current investigation is developing a model for the installation of PTSC on solar-powered ships under various provided assumptions. [ABSTRACT FROM AUTHOR]

Concentrated solar power (CSP) has gained traction for generating electricity at high capacity and meeting base-load energy demands in the energy mix market in a cost-effective manner. The linear Fresnel reflector (LFR) is valued for its cost-effectiveness, reduced capital and operational expenses, and limited land impact compared to alternatives such as the parabolic trough collector (PTC). To this end, the aim of this study is to optimize the operational parameters, such as the solar multiple (SM), thermal energy storage (TES), and fossil fuel (FF) backup system, in LFR power plants using molten salt as a heat transfer fluid (HTF). A 50 MW LFR power plant in Duba, Saudi Arabia, serves as a case study, with a Direct Normal Irradiance (DNI) above 2500 kWh/m2. About 600 SM-TES configurations are analyzed with the aim of minimizing the levelized cost of electricity (LCOE). The analysis shows that a solar-only plant can achieve a low LCOE of 11.92 ¢/kWh with a capacity factor (CF) up to 36%, generating around 131 GWh/y. By utilizing a TES system, the SM of 3.5 and a 15 h duration TES provides the optimum integration by increasing the annual energy generation (AEG) to 337 GWh, lowering the LCOE to 9.24 ¢/kWh, and boosting the CF to 86%. The techno-economic optimization reveals the superiority of the LFR with substantial TES over solar-only systems, exhibiting a 300% increase in annual energy output and a 20% reduction in LCOE. Additionally, employing the FF backup system at 64% of the turbine's rated capacity boosts AEG by 17%, accompanied by a 5% LCOE reduction. However, this enhancement comes with a trade-off, involving burning a substantial amount of natural gas (503,429 MMBtu), leading to greenhouse gas emissions totaling 14,185 tonnes CO₂ eq. This comprehensive analysis is a first-of-a-kind study and provides insights into the optimal designs of LFR power plants and addresses thermal, economic, and environmental considerations of utilizing molten salt with a large TES system as well as employing natural gas backup. The outcomes of the research address a wide audience including academics, operators, and policy makers. [ABSTRACT FROM AUTHOR]

This paper proposes the Hybrid desalination and power generation through parabolic trough collectors. This study aims to examine the feasibility, performance optimization, and economic viability of power-generation plant and hybrid-desalination using multi-stage flash (MSF) and reverse osmosis (RO) technologies assessed by using the parabolic trough collectors (PTC). The objective is to discover the posibilities of this innovative approach in addressing water scarcity and clean energy demands. The studies usually focus on several key aspects. Firstly, it resolves the technical feasibility of integrating MSF and RO technologies with parabolic-trough-collectors to optimize energy efficiency and freshwater production. This involves evaluating the system design, heat transfer mechanisms, and operational parameters.Secondly, performance optimization is a key area of investigation. By optimizing these parameters the aim is to maximize freshwater production while minimizing energy consumption. Thirdly, the economic viability of the hybrid plant will be assessed. This involves considering capital investment, conducting a comprehensive cost analysis, maintenance costs, and operational expenses. The study also evaluates the potential for revenue generation through the sale of excess electricity produced by the system. The potential outcomes of this research include demonstrating the technical-feasibility as well as economic-viability of the hybrid desalination and power generation plant. The findings may indicate that this approach can effectively address water scarcity challenges while contributing to clean energy production. The study may also highlight the environmental benefits of integrating renewable energy sources (RESs) and decreasing greenhouse gas emissions compared to traditional desalination methods.The proposed method is executed in MATLAB platform and compared to various existing approaches. [ABSTRACT FROM AUTHOR]

Optical Wireless Communications (OWCs) are capable of handling large data rates in the Internet of Underwater Things (IoUT) at low latency to be suitable for real-time image and video applications. This paper presents communication link feasibility via link budget to determine the link communication range for three types of line-of-sight link configurations: point-to-point, diffused, and modulating retro-reflector link. The main aim of this paper is to present a more realistic power link budget which is developed to take into account the following: LED Photo Source Lambertian radiation model, Beer-Lambert pass loss model that includes absorption and scattering effects of water types, Spherical wave propagation model, photodetector which is modeled by active area model, transmitter projection optics (PO) gain and receiver collection optics (CO) gain. Moreover, this paper considers the effects of aquatic channels 'scattering and absorption by using intensity modulation direct detection IM-DD OOK, LED and LD–PS based transmitter, and SiPM-PD based receiver. The impact of different underwater environments, transmitter, and receiver parameters will be investigated on the communication link range. Its communication range on the order of tens of meters could be achieved by the three-link configurations. It is concluded from the analysis; that the line-of-sight point-to-point provides more communication range than a diffused line of sight. A diffused line of sight is used when it is required to multicast from a node to several nodes. Modulating retro-reflector provides moderate communication range and it is used when one party has more resources than the other one on the communication link. Medium distances are achieved by up to a hundred meters by placing multiple relay nodes between the source node and the destination node. The communication range is increased as increasing the active physical area of the photodetector and the transmitted power of the photo source. The communication range in both clear sea water and clear ocean water is higher than turbid water which is less since optical water suffers from higher attenuation. By using the multi-hop concept, an extended communication link range can be achieved. [ABSTRACT FROM AUTHOR]

This work introduces an innovative methodology to enhance the efficiency of solar Parabolic Trough Collectors by integrating corrugated tube receivers accompanied by conical strip inserts. Conventional optimization techniques involving adjustments in size, material composition, and insert configurations often necessitate supplementary energy input. A concept centered around augmenting turbulence was introduced, employing corrugated tube receivers to address this challenge. The study encompassed empirical investigations employing three corrugated copper tube receivers, each possessing distinct pitches (8 mm, 10 mm, and 12 mm) while maintaining uniform corrugation heights (2 mm). These experiments were conducted within a regime of laminar flow conditions characterized by Reynolds numbers spanning from 700 to 2000. The primary objective was to identify the most favorable absorber geometry, subsequently coupled with three varying pitches of conical strip inserts (20 mm, 30 mm and 50 mm) to intensify heat transference. The findings unveiled that the corrugated tube with an 8 mm pitch and 2 mm corrugation height, combined with a conical strip insert possessing a pitch of 20 mm, exhibited promising results. This specific amalgamation yielded remarkable enhancements in the augmented Nusselt number (132%), friction factor (38%), and thermal efficiency (9%) in contrast to the unadorned tube operating under analogous conditions. These outcomes underscore the substantial potential of this pioneering approach in significantly elevating the overall performance of solar parabolic trough collectors. [ABSTRACT FROM AUTHOR]

Present paper aims to investigate effects of nanoparticle addition to thermal oil of parabolic trough collectors which are integrated to Kalina cycle for electricity generation to run an alkaline electrolyzer for hydrogen production. Thermodynamic models for Kalina cycle, thermal model for parabolic collectors and electrochemical models for water electrolyzer are developed for overall plant modeling. Three types of nanoparticles including: copper oxide, alumina and titanium oxide are considered and overall plant performance is investigated using these nanoparticles and is compared with basefluid. The nanofluid thermophysical properties are evaluated as a function of nanoparticles' properties, volume fraction and the base fluid properties. The effects of key variables such as nanoparticle volume fraction, collector inlet temperature, evaporation pressure and ammonia concentration of Kalina system were evaluated on hydrogen production as well as exergetic efficiencies. Results revealed greater positive influence for CuO compared to TiO 2 and Al 2 O 3 on performance improvement for both hydrogen generation and its exergetic efficiency. Also, compared to basefluid (without nanoparticles) case, it was found that CuO particles result in a solar-to-H 2 exergy efficiency improvement by 4.7%. Using this nanofluid with a volume fraction of 5%, the H 2 production rate enhances from 0.633 kg / h to 0.664 kg / h , indicating 4.9 % improvement. • An alkaline electrolyzer-based hydrogen production plant powered by PTC is modeled. • Three types of nanoparticles are employed for hydrogen production enhancement. • Copper oxide nanoparticles are found to be better than titanium oxide and alumina. • Nanoparticles are applied to enhance the PTC thermal performance. • Hydrogen production rate can be enhanced by 4.9 % using CuO nanoparticles. [ABSTRACT FROM AUTHOR]

The environmental impact caused by the intensive exploitation of fossil fuels to generate heat and electricity has already reached a critical level. Also, as the industrial sector is the largest energy consumer, mainly in the form of heat, it has then become compulsive to implement the use of renewable solar heat in industrial processes, such as those found in the food processing and beverages industries, which do not require high temperatures. Consequently, this study examines the viability of supplying heat as hot water at 80 °C and saturated steam at 160 °C to a medium-sized brewery factory through a hybrid solar plant composed of flat plate and parabolic trough collectors and sensible thermal energy storage. The study was conducted numerically using the meteorological conditions of a city different from that where the factory is located because it benefits from higher insolation levels. The mean annual solar fractions achieved were 49.9% for hot water production and 37.3% for steam generation, at a levelized cost of heat of 0.032 USD/kWh, which can be considered competitive if compared against the values reported in other similar solar projects. Also, the decrease in fossil fuel consumption allowed an annual reduction of 252 tons of carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

Today, the world is turning to use renewable energy to solve the problems of fuel shortage and pollution due to CO2 emissions from the use of fossil fuels. In this study, parabolic trough solar collectors (PTC) with two types of heat transfer fluids HTF are used to investigate the performance of a retrofitted steam power plant using solar energy. A thermo-economic analysis was performed for a 10 MW simple steam power plant with different boiler pressure from 10 to 100 bar and located in the city of Basra in Iraq which receives high levels of solar radiation. Basra's weather conditions are used to simulate the solar-assisted regenerative system using a parabolic trough collector (PTC). According to the system analysis, it was found that increasing the boiler pressure reduces the area required for the PTC heater for constant power output. For 10 bar operating pressure the required PTC area is 64233,562 m² while for 100 bar operating pressure the required PTC area is 42907.59 m². Also, it was estimated that the Levelized Cost of Energy (LCOE) decreased with increasing operating pressure. The decrease in LCOE for PV1 heating fluid is 43.25% and the decrease in LCOE is 43.16% for the pressure range from 10 to 100 bar. [ABSTRACT FROM AUTHOR]

In order to reduce greenhouse gas emissions and achieve global decarbonisation, it is essential to find sustainable and renewable alternatives for electricity production. In this context, the development of distributed generation systems, with the use of thermodynamic and photovoltaic solar energy, wind energy and smart grids, is fundamental. ORC power plants are the most appropriate systems for low-grade thermal energy recovery and power conversion, combining solar energy with electricity production. The application of a micro-scale ORC plant, coupled with Parabolic Trough Collectors as a thermal source, can satisfy domestic user demand in terms of electrical and thermal power. In order to develop a micro-scale ORC plant, a commercial hermetic scroll compressor was tested as an expander with HFC-245fa working fluid. The tests required the construction of an experimental bench with monitoring and control sensors. The aim of this study is the description of the scroll performances to evaluate the application and develop optimization strategies. The maximum isentropic effectiveness is reached for an expansion ratio close to the volumetric expansion ratio of the scroll, and machine isentropic effectiveness presents small variations in a wide range of working conditions. The filling factor is always higher than one, due to leakage in the mechanical seals of the scroll or other inefficiencies. This study demonstrates that using a commercial scroll compressor as an expander within an ORC system represents a valid option for such applications, but it is necessary to improve the mechanical seals of the machine and utilize a dedicated control strategy to obtain the maximum isentropic effectiveness. [ABSTRACT FROM AUTHOR]

The aim of this experimental and modeling work is to compare the thermal efficiency of two identical parabolic trough solar collector systems under weather conditions in Amman, Jordan, using a hybrid nanofluid of MWCNTs and Y2O3 with gum Arabic surfactant, and distilled water as the heat transfer fluid (HTF). One parabolic trough collector (PTC) uses a hybrid nanofluid at four different volumetric concentrations (0.01, 0.025, 0.05, and 0.1%), while the other uses water as a HTF. To prepare the nanofluids and check their stability, the thermal efficiency of the PTC was examined for different hybrid nanofluid concentrations compared to distilled water. The results showed that the 0.1% MWCNTs and Y2O3 hybrid nanofluid had the highest thermal efficiency of 44.24%, while water had a thermal efficiency of 19.32%. In addition, increasing the concentrations resulted in an improvement in the maximum optical efficiency. The maximum efficiency of 45% was obtained using 0.1% Vol. The Solidworks model was created according to experimental setup parameters and dimensions. The simulation was conducted under steady-state operating conditions, incorporating dimensional governing equations (continuity, momentum, and energy). A uniform heat flux was applied with two primary boundary conditions: the first one was at the receiver inlet where the fluid inlet temperature and mass flow rate were specified, whereas the second one was at the receiver outlet, where the outlet pressure was equivalent to the atmospheric pressure. The obtained experimental results have been compared using the Solidwork simulation model, which was created to determine the PTC's outlet temperature and thermal efficiency. The comparative results demonstrated remarkable precision with an average outlet temperature of 0.03% and thermal efficiency of 0.9%. [ABSTRACT FROM AUTHOR]

In pursuit of sustainable development and mitigation of the intermittency challenge associated with solar energy, this study proposes a hybrid solar system integrating waste heat incineration alongside solar power generation and distinct heat provision. Leveraging the superior energy efficiency of the organic Rankine cycle (ORC) in medium- and low-temperature scenarios, a parabolic trough collector (PTC) is selected for its cost-effectiveness and long-term operational reliability. Dowtherm A and toluene are identified as the optimal working fluids for the PTC and ORC, respectively. To optimize this complex system, a combination of artificial neural networks (ANNs) and multi-objective optimization via non-dominated sorting genetic algorithm II (NSGA-II) is employed, streamlining the optimization process. Thermal dynamic simulations are executed using Engineering Equation Solver (EES, V11) to validate the proposed system's performance. TOPSIS is employed to identify the optimal solution from the Pareto frontier. The results indicate that the hourly cost of the system stands at USD 43.08, with an exergy efficiency of 22.98%. The economic analysis reveals that the solar collector constitutes the most significant portion of the total initial cost, representing 53.2%, followed by the turbine, thermoelectric generator (TEG), and waste heat incineration, in descending order of costliness. [ABSTRACT FROM AUTHOR]

This paper aims to compare the performance and efficiency of fluid-driven (FD) and solid-state (SS) systems, which are used for solar heating using parabolic trough. Sodium nitrite (NaNO2) was considered as phase change material (PCM) and both storages had the same storage capacity. To evaluate system performance, constant heating of 1 kW was provided to both systems to replicate solar energy. The fluid-driven system showed maximum efficiency of around 47% as compared to 20% of solid-state system. Although the operating temperature of FD is higher than SS, as temperature increases flow rate of fluid also increases in FD which results in reducing the melting time of PCM. FD shows potential for providing better efficiency and can help utilize solar energy during evening/night when no sun is present. [ABSTRACT FROM AUTHOR]

This study marks the pioneering utilization of thermal efficiency involving non-Newtonian Carreau nanofluids within parabolic trough solar collectors (PTSCs). The research delves into nanofluids encompassing copper-engine oil, copper (II) oxide-engine oil, and iron (II, III) oxide-engine oil Carreau nanofluids within PTSCs. Evaluation of PTSC's heat efficiency encompasses a spectrum of physical phenomena, including porous medium effects, slanted magnetic fields, non-uniform heat sources/sinks, thermal radiation, viscous dissipation, and thermophoresis. Additionally, the study investigates the influence of several parameters governing nanofluid flow on velocity, temperature, entropy generation, skin friction coefficient, and local Nusselt number of the Carreau nanofluids within PTSC setups. The research adopts a theoretical model that represents the flow and thermal dynamics of PTSCs integrated into a solar-powered aircraft, highlighting the pivotal role of nanoparticle thermal conductivity. Numerical results reveal substantial enhancements in heat efficiency within engine-oil Carreau nanofluids, encompassing copper, copper (II) oxide, and iron (II, III) oxide. These enhancements translate to relative increments of 68.490%, 50.292%, and 42.013% in maximum heat performance, underscoring the potential of Carreau nanofluids to elevate PTSC efficiency, suggesting a theoretical model for their potential application in solar-powered aircraft. Overall, this study holds promise for cleaner and more sustainable energy applications in the realms of solar energy and solar-powered aircraft. The execution of intricate engineering simulations falls beyond the scope of our current study. [ABSTRACT FROM AUTHOR]

Textile industry wastewater containing toxic dyes and high COD poses environmental hazards and requires treatment before discharge. This study addresses the challenge of treating complex textile wastewater using a novel integrated system. The system combines sedimentation, screening, adsorption, and an optimized solar photo-Fenton process to provide a sustainable treatment solution. A novel parabolic collector with a larger absorber tube diameter enhances solar radiation utilization at lower catalyst concentrations. This design is versatile, treating all types of wastewaters, especially those that contain colors, smells, solid and suspended materials, in addition to its importance for the treatment of difficult substances that may be present in industrial and sewage wastewaters that are difficult to dispose of by traditional treatment methods. Multivariate experiments optimized key photo-Fenton parameters (pH, catalyst dose, etc.) achieving significant pollutant removal (85% COD, 82% TOC, complete color) under specific conditions (pH 3, 0.2 g/L Fe(II), 1 mL/L H2O2, 40 °C and 100 L/h flow rate after 60 min irradiation). Kinetic modeling revealed second-order reaction kinetics, and multivariate regression analysis led to the development of models predicting treatment efficiency based on process factors. The key scientific contributions are the integrated system design combining conventional and advanced oxidation technologies, novel collector configuration for efficient utilization of solar radiation, comprehensive process optimization through multivariate experiments, kinetic modeling and predictive modeling relating process factors to pollutant degradation. This provides an economical green solution for textile wastewater treatment and reuse along with useful design guidelines. The treatment methodology and modeling approach make valuable additions for sustainable management of textile industry wastewater. [ABSTRACT FROM AUTHOR]

These days, thermal power and industrial processing rely heavily on solar energy. This study examines the heat dispersion in Casson nanofluid flow across an expanding cylinder by considering nano aggregate kinematics. Ethylene glycol-Cu nanofluid is deemed to boost the heat transfer competence of parabolic trough collector (PTSC). A stable magnetic field is used in the radial direction in the appearance of asymmetrical heat source/sink, radiative, and Joule heats. A mathematical model was developed and resolved using the Keller-box approach. Results are deliberated through pictorial and numerical evaluations for aggregation and non-aggregation cases. The improvement of the thermal field caused by nanoparticle aggregation is proven. It is also found that the surface drag and thermal transfer rate can be controlled by increasing the Darcy parameter. [ABSTRACT FROM AUTHOR]

This paper is a summary of the last ten years of work on the study of parabolic trough collectors (PTCs) and compound parabolic collectors (CPCs) coupled to photovoltaic and thermal solar receiver collectors (SCR-PVTs). While reviewing the state of the art, numerous review papers were found that focused on conventional solar receiver collector (SRC) technology for solar thermal generation. However, there is a lack of review papers summarizing SRC-PVT hybrid technology for solar electric/thermal generation, which would be beneficial for researchers interested in this area of research. This paper provides a review of SRC-PVT hybrid technologies. The theoretical foundations for analyzing and modeling PTC and CPC concentrators coupled to SRC-PVT are described, with an emphasis on modeling through thermal resistances and energy balances. Additionally, this section provides a concise overview of previous studies that have addressed the modeling of PTC and CPC collectors coupled to SCR-PVT, as well as experimental information useful for the validation of new mathematical models of SRC-PVT. [ABSTRACT FROM AUTHOR]

Combination of different power cycle scenarios is of prime importance in achieving maximum energy utilization from solar‐driven multigeneration systems. To fulfill such objective, the present article proposes a novel energy distribution system, leveraging a combination of direct‐fed organic Rankine cycle (ORC) and a bottom‐cycled arrangement of Kalina cycle system (KCS) and double‐effect absorption refrigeration cycle (DEARC) within a parabolic trough solar collector powered trigeneration system. The study explores three different ORC configurations: simple ORC; ORC equipped with internal heat exchanger (ORC‐IHE) and regenerative ORC (RORC). It is shown that although higher efficiencies are achievable from a larger portion of PTSC energy absorbed by the ORC, the ORC energy absorption is limited by ORC evaporator temperature differences, and there is unused energy that can be recovered by the KCS, based on the proposed energy system. The results indicate that the addition of bottoming KCS leads to a considerable increase in the exergy efficiency of ORC, ORC‐IHE and RORC‐based systems by 11.7%, 30.7% and 32.6%, respectively. The impact of different ORC configurations, key ORC parameters and various organic working fluids on the energetic/exergetic efficiencies is also examined to find the optimal configuration. In terms of overall energetic/exergetic efficiencies, the highest performance belongs to ORC (78.4%/30.4%) while the lowest energetic and exergetic efficiencies belong to ORC‐IHE and RORC, respectively (56.3% and 25.65%). On the basis of a comparative study with the available literature, these values are higher than what is already reported for similar solar‐driven multigeneration systems. Appropriate thermal match and lower exergy destruction in the KCS, and bottoming cycle arrangement of the DEARC are the main reasons for such enhanced performance. This research not only contributes valuable insights into efficient solar‐driven systems but also sets a new benchmark for performance metrics in the existing literature. [ABSTRACT FROM AUTHOR]

Parabolic trough collectors (PTCs) have came out as a promising technology for harnessing solar energy for various applications including electricity generation and thermal heating. However, improving their thermal performance remains a critical challenge to maximize energy conversion efficiency. This paper presents a mathematical model for enhancing the thermal performance of PTCs by using a curved Fresnel lens as a second collector over the top side of the receiver. This enhancing has taken advantage of the space above the top side of receiver and increased the thermal efficiency of PTCs. The unsteady heat transfer equations with one dimension are used to simulate the effect of Fresnel lens on the receiver components beside the heat transfer fluid and compared with that without Fresnel lens. The results of this model are based on parameters of LS-2 model and environment of installation place whereas the water was chosen as heat transfer fluid with physical properties depending on Temperature. Albaydha city in Yemen is chosen as an installation place taking in consideration the variation of environment temperature in each month of the year and the inlet temperature of water and receiver's components are taken as the minimum temperature of the air. [ABSTRACT FROM AUTHOR]

This research investigates the incorporation of solar power systems into buildings to meet the energy needs of near-zero-energy buildings. The study focuses on a complex buildings in Shiraz City, Iran. The primary objective of this case study is to integrate an innovative method of hydrogen production known as thermochemical hydrogen production methods to fulfill the building's energy demands. Solar energy is utilized to generate heat by parabolic trough collectors, which is the sole energy source required for the V–Cl thermochemical cycle. Consequently, hydrogen is produced and stored during the day for use at night when there is no solar radiation. To address this, a novel component has been developed for the vanadium chlorine cycle (V–Cl) within the TRNSYS software. The energy system was simulated using the TRNSYS software, a powerful transient simulation tool. Despite the numerous advantages offered by TRNSYS's energy system simulation, it lacks optimization capabilities. The use of a neural network-genetic algorithm optimization approach allows for the calculation of an optimized area for collectors and the power output of fuel cells for the building complex. The optimum configuration results in minimum installation cost, lowest CO 2 emissions, and the highest power supply renewable (PSR). The results reveal that the installation of collectors with a surface area of 70 m2 and the utilization of fuel cells with a power output of 345 kW lead to a total carbon dioxide (CO 2) generation of 10.31 tons per year, a PSR of 1.21, and a cost of $4.915 per hour. • Modeling and investigation of a building complex consisting of restaurants. • Solar energy system to provide the power requirements of a building using TRNSYS. • Using vanadium chlorine thermochemical cycle to produce and store hydrogen. • A neural network-genetic algorithm technique for optimization. • System development to find the optimal balance between cost and emissions. [ABSTRACT FROM AUTHOR]

Solar energy is a natural renewable energy source. The sunlight that spreads the earth's atmosphere is sufficient to power all of our essentials. The real-world usage of solar energy is critical to fulfilling current and future needs. This article focuses on the vital use of solar energy by utilizing the nanoaggregation concept. A suitable mathematical model is established by considering the flow slip, hydrodynamics, Ohmic, and radiative heats. The modeled problem was resolved using R-K-based shooting process. Simultaneous outcomes are obtained for the aggregation and nonaggregation cases. This study is a practical application of enhanced heat transport in Parabolic Trough Solar Collector (PTSC). It is found that nanoparticle aggregation aids in enlarging the thermal conduction rate of PTSC. This helps with the practical usage of solar energy. [ABSTRACT FROM AUTHOR]

The primary scope of the present work is the comprehensive investigation of a novel multigeneration system that exploits renewable energy sources, i.e. solar energy, geothermal energy, and biomass, and produces four useful outputs, i.e. electricity, heating, cooling, and green hydrogen. Solar irradiation is the primary energy source, which is exploited by parabolic trough collectors and powers a supercritical CO 2 regenerative Brayton cycle, while a biomass boiler serves as an auxiliary energy input. In addition, the whole installation includes a proton exchange membrane water electrolyzer, a water heater, as well as an absorption chiller, where a geothermal well is used for heat rejection. Apart from the thermal energy storage tank, which is coupled with the collectors, hydrogen production is used as a secondary energy storage method, as the excess produced renewable electricity feeds the electrolyzer. Consequently, the installation is examined parametrically, and optimized on steady-state conditions. Then, a dynamic simulation study is conducted for the climate data of Athens, Greece. According to the results, at the optimum operation point on steady-state conditions, the energy efficiency is determined at 37.89%, and the exergy efficiency at 20.86%. Moreover, the annual energy and exergy efficiencies are defined at 32.52%, and 18.51%, respectively. The economic evaluation analysis indicates that the payback period is about 11 years, while the internal rate of return, and the net present value are determined at 10.62% and 7,753,905 €, respectively. In addition, the system is estimated to save 3072.6 tons of CO 2 equivalent per annum. In conclusion, the proposed multigeneration system can address the various energy needs and recent environmental challenges, as a totally renewable, economically feasible, and environmentally friendly solution. • A multigeneration system that produces four useful outputs is examined. • The unit exploits three renewable sources, solar, biomass, and geothermal. • Both steady-state and dynamic analyses are carried out. • The annual energy and exergy efficiencies are defined at 32.52% and 18.51%. • The system payback period is found at 11 years, while it saves 3072.6 tn CO2-eq. [ABSTRACT FROM AUTHOR]

This paper proposes a novel solar-based polygeneration system for simultaneous power generation, desalination, hydrogen-production, and refrigeration. The system integrates parabolic trough solar collectors, multi-effect distillation, polymer electrolyte membrane electrolyzer, Kalina cycle, organic Rankine cycle, Brayton cycle, and ejector cooling. Solar energy and waste heat from the Brayton cycle provide energy input. Power generation is achieved via the Brayton, Kalina, and organic Rankine cycles. The multi-effect distillation unit produces freshwater while the electrolyzer generates hydrogen. The ejector system supplies cooling. A comprehensive steady-state energy and exergy analysis evaluates the thermodynamic performance. The system attains 32.269 MW net power output and ejector COP of 0.3193. The overall energy and exergy efficiencies are 38.45% and 35.64%, respectively. The combustion chamber exhibits maximum exergy destruction. Exergoeconomic analysis determines associated costs and investment feasibility. Integrating multiple technologies into a system with solar input enhances efficiency, sustainability, and environmental benefits. • Presents novel solar multi-generation system integrating power, hydrogen, water and cooling generation • Validated methodology analyzes thermodynamic performance providing insights on efficiencies • Exergy destruction analysis identifies optimization opportunities in integrated solar systems • Showcases potential of intricate integration of solar, desalination, hydrogen and power for sustainable energy • Modular and scalable system design enables flexibility for different applications and demands [ABSTRACT FROM AUTHOR]

The paper offers innovative cooking utensil designs for remote, isolated, and even peri-urban communities at a low price, with high reliability and simple construction. It can alleviate energy poverty and improve food security. This utensil uses only local solar energy directly and allows comfortable indoor cooking. This paper provides the design principles of a solar cooker/frying pan or generic heater, based on a PV panel or a plurality of them, which are directly connected to a plurality of Positive Thermal Coefficient (PTC) resistors to match the power. PTCs are nowadays produced in massive quantities and are widely available at low cost. The proposed device does not require an electronic controller or a battery for its operation. The aim is for family use, although the design can be easily scaled to a larger size or power, maintaining its simplicity. Electric heating inside or attached to the cooking pot, plus the temperature self-limiting effect of PTCs, allows for thermally insulating the cooking pot from its outside using ordinary materials. Insulation enhances energy efficiency during cooking and keeps cooked food warm for a long time. Clean development would receive a significant impulse with its application. A simple mathematical model describes its functioning and states guidelines for adequate design. Its results indicate a successful proof of concept and high efficiency both for water and oil as representatives of cooking. [ABSTRACT FROM AUTHOR]

This research entails the simulation and thermodynamic evaluation of a combined solar‐powered system that is intended to achieve the energy necessary to construct factories in areas where other sources of energy are not available. The system comprises five major circuits: (1) a parabolic trough that collects solar energy and passes it to downstream circuits via an evaporator, (2) an organic Rankine cycle that generates electricity for devices and factories, (3) a proton exchange membrane electrolysis unit that produces hydrogen from pure water, (4) a methanation unit that produces gas by combining hydrogen and carbon dioxide, and (5) a reverse osmosis (RO) unit that purges seawater to produce freshwater. This investigation studies the efficiency of energy and exergy, the destruction rate of exergy, and the economic value of system components as a whole. The system is represented by the technical equation solver, and the results are obtained as a result. This research employs the genetic algorithm and Technique for Order of Preference by Similarity to Ideal Solution method to locate the most effective point. The achieved outcomes include a maximum total system efficiency of 54.935% and a minimum total cost of 2.578 $/GJ. Dated to the optimal point, the power generated is 305.5 kW, the required power of a single‐cell electrolyzer is 293.8 W, the mass flow rate of methane and hydrogen production is 448.92 kg/hr ${kg}/{hr}$ and 225.64 kg/h, respectively. The water volume generated by RO is 35.25 m3/h, and the total cost of the investment is 85.57 $/h. [ABSTRACT FROM AUTHOR]

To enhance the performance of the parabolic trough solar collector (PTSC) and mitigate the circumferential temperature gradient within the absorber tube, a numerical simulation investigation was conducted involving the implementation of vortex generators. The vortex generator was composed of a ring belt and four ribs, and four types of vortex generators M1, M2, M3 and M4 were proposed. The flow and heat transfer of the absorber tube were analyzed at Reynolds numbers ranging from 10000 to 35000 and inlet temperatures between 373.15 K and 473.15 K, using the shear stress transport (SST) k-ω turbulence model. The results show that the four kinds of vortex generators—M1, M2, M3 and M4—can induce longitudinal vortices in the heat transfer fluid (HTF) within the absorber tube. These longitudinal vortices diminish the thermal boundary layer's thickness, expedite the mixing of cold and hot fluids, and enhance the overall heat transfer efficiency. Vortex generators M1 and M3 arranged in the reverse direction produce two pairs of reverse rotating longitudinal vortices, while vortex generators M2 and M4 arranged in the same direction form one pair of longitudinal vortices, so the flow resistance in M1 and M3 is slightly larger than M2 and M4. However, from the perspective of heat transfer enhancement effect and comprehensive performance, the vortex generator M3 has the best effect. In M3, the Nu/Nu0 reached the highest value of 1.238, and the performance evaluation criteria (PEC) for M3 exceeded 1, reaching a maximum of 1.11. [ABSTRACT FROM AUTHOR]

The main source of thermal energy is the sun, and with the increase in solar technology, it is now being utilized in many devices such as sun-based panels, photovoltaic cells, batteries and lights, solar fabric, solar water pumping, etc. Nowadays, improvement in flight effectiveness of solar aircraft by utilizing solar energy and nanotechnology is being studied by many scientists. This article is also based on studying the effectiveness of solar aircraft based on solar energy and nanotechnology. For this purpose, few properties of heat transfer among symmetrical wings will be analysed such as porous surface, thermal radiation, convective condition and heat source/sink. It is considered that the ternary hybrid nanofluid moves through the internal side of parabolic trough solar collector. The current study examines the radiative flow of a Carreau tri-hybrid nanoliquid across a convectively heated stretching surface in porous media. Also entropy generation on Carreau fluid is analysed in this work. Energy equation is modelled through heat source/sink and thermal radiation. The well-established numeric technique BVP4c has been used to solve the system of differential equations in the form of concentration, energy and momentum. Several flow variables on fluid velocity, temperature, drag friction, the Nusselt, entropy generation and Bejan number are described in figures and tables. The main outcomes of the current investigation are that the velocity and temperature lowered with augmenting values of Weissenberg number We . Results will prove that THNF is larger in the case of HNF and NF. Further, the drag friction and thermal efficiency of Thnf ( MoS 2 + SiO 2 + Fe 3 O 4 /EG ), Hnf ( MoS 2 + SiO 2 /EG ) and Nf ( MoS 2 /EG ) are computed in percentage with numerous values. The second finding is the addition of entropy due to the increasing magnitude of radiative flow, Carreau fluid variable. When comparing the current results to the reported results, we get a close match. [ABSTRACT FROM AUTHOR]

In areas with unreliable electricity, the absorption system serves as a crucial, eco-friendly refrigeration technology. This study addresses the system's performance gaps, evaluating the 100 W NH3-H2O absorption cooling system under various conditions. The focus is on its suitability for electricity-challenged areas, employing theoretical and experimental methods. Two configurations are tested based on input heat sources, using bifacial Photovoltaic (PV) or solar parabolic troughs integrated with the absorption chiller. The Engineering Equation Solver (EES) program determines thermodynamic properties, with the model split into sections--one with the solution heat exchanger (SHX) excluding the liquid-vapor heat exchanger (LVHX) and the other incorporating both. The findings indicate a direct correlation between higher evaporator and generator temperatures and an increase in the Coefficient of Performance (COP). The theoretical and experimental cooling COP values reach 0.62 and 0.63, respectively, at 7℃ evaporator temperature and 85℃ generator temperature. Similarly, at 95℃ generator temperature, the COP values are 0.629 and 0.637 for the same evaporator temperature. The theoretical maximum COP at 3℃ evaporator temperature is 0.512 at 90℃ generator temperature, with experimental COP approaching 0.52 at generator temperatures of 96℃, 98℃, and 100℃. The integration of an LVHX into the chiller module demonstrates a notable improvement in cycle performance, enhancing efficiency by approximately 7-7.5%. In conclusion, this study offers crucial insights into optimizing the NH3-H2O absorption cooling system for off-grid scenarios, contributing to a broader understanding of absorption refrigeration technology in diverse environmental conditions. [ABSTRACT FROM AUTHOR]

Combined concentrated solar power with photovoltaics can provide electricity and heat at the same system while maximizing the power output with reduced losses. Spectral splitting is required in such systems to separate the infrared part of the solar spectrum towards the thermal system, while the visible and near-infrared radiation can be converted by the photovoltaic solar cell. The performance of concentrated solar power plants comprising reflective beam splitters for combined generation of electricity and heat is presented in this work. A 50 MW power plant is considered in this work as a case of study in Southern Crete, Greece. The solar power plant consists of parabolic trough collectors and utilizes beam splitters with varying reflectivity. The dynamic performance of the power plant is modeled, and the annual energy yield can be calculated. Up to 350 MWt of thermal power can be delivered to the photovoltaic system utilizing a 50% reflecting splitter. The penalty to the high-reflectivity system is limited to 16.9% and the annual energy yield is calculated as 53.32 GWh. During summer months, a higher energy yield by up to 84.8 MWh/month is produced at 80% reflectivity compared to 90% as a result of the number of parabolic troughs. The reported energy yields with reflectivity by dynamic modeling can highlight discrete points for improvement of the performance in concentrated solar power photovoltaics. [ABSTRACT FROM AUTHOR]

Steam cooking using parabolic trough collectors is a well-established sustainable technology. The augmentation of a thermal energy storage (TES) system with such a sustainable system will make the technology completely reliable on the renewable energy source. However, there are limited research findings to improve the thermal performance of the TES heat exchangers by adopting non-structural and non-elemental modifications. In this article, experimental studies have been performed on a TES shell and tube heat exchanger that could be envisaged for steam cooking applications. Erythritol was used as the phase change material. The heat exchanger was operated in two modes: progressive and impulsive. From the observations, the performance of the impulsive mode was better than the progressive mode. The impulsive mode of functionality witnessed a 32% decrease in the charging duration, 2.5% increase in the energy stored and 50% increase in the charging rate in comparison to the progressive mode. [ABSTRACT FROM AUTHOR]

This work researches producing electricity and hydrogen production performance of a solar pond integrated with parabolic trough solar collectors. The system consists of parabolic trough solar collectors and a solar pond with a surface area of 100 m2 and 200 m2, an organic Rankine cycle operating with n-butane for electricity production, a proton exchange membrane for generating hydrogen, and a mushroom production unit. The system was operated for five mass flow rates m ˙ 1 = 0.350 k g / s , m ˙ 2 = 0.355 k g / s , m ˙ 3 = 0.360 k g / s , m ˙ 4 = 0.365 k g / s , m ˙ 5 = 0.370 k g / s. To improve the overall system performance, n-butane is selected as the operating fluid in the organic Rankine cycle and the waste heat of the organic Rankine cycle was used to heat the mushroom production unit. In addition, the preheating water produced by the solar pond was transferred to the parabolic trough solar collectors via a pump. The temperature of this preheated water was quickly raised by the parabolic trough solar collectors and pumped to the organic Rankine cycle. Thus, the organic Rankine cycle's electricity generation performance was also tried to be increased. With efficient electricity produced, the hydrogen production performance of the proton exchange membrane was improved. Thus, the amount of hot water, electricity, and hydrogen produced in the integrated system, the organic Rankine cycle, the parabolic trough solar collectors, and the energy and exergy efficiencies of the entire system were determined daily for five different masses. As a result, for five different masses, it was found in which mass the system performed the best. The whole system was analyzed with the engineering equation solver program. It was found that the system performs best at noon for all mass flow rates. It was also found that the performance of the system, the amount of electricity, and the hydrogen it produced increased as the amount of mass decreased. It was seen that hydrogen can be produced as 534.32 g and 519.06 g for m ˙ 1 and m ˙ 5 in a day, respectively. The energetic and exergetic efficiencies of the system were also found to be a maximum of 13.77% and 5.79% for m ˙ 1. • Hydrogen production of a different solar integrated system. • Thermodynamic performances of the parts of the system and overall system. • The comparison of the hydrogen production for five different mass flow rates. • The effect of thermal energy on hydrogen production in a day. [ABSTRACT FROM AUTHOR]

A cogeneration of power and hydrogen plant driven by clean solar energy is developed, analyzed and optimized in this paper. For hydrogen production in the suggested plant, a thermochemical cycle with Vanadium–Chlorine (VCl) working pair is integrated with parabolic trough collectors and an auxiliary heater to provide the required temperature level. For power generation, however, an organic Rankine cycle is applied to generate electricity from extra heat which is not utilized in VCl thermochemical cycle. For performance improvement of developed cogeneration framework, nanoparticles are applied for enhancing thermal behavior of collector field. A comprehensive analysis is conducted to determine system performance enhancement with nanufluid as compared to basefluid case in thermal loop of collectors. Thermodynamic investigations paying more attention on exergy evaluations are carried out along with economic considerations to assess system performance. Furthermore, to address the proposed plant's environmental impacts, the overall plant's performance and carbon dioxide emission reduction are estimated. Parametric appraisal is implemented to specify operating factor impacts on power and hydrogen production and unit cost of product. Also, multi-objective optimization is performed based on cost and efficiency indices. It is found that, addition of nanoparticles to basefluid can enhance system performance roughly by 3 − 5 %. The nanofluid based framework attains efficiency of 40.16% and unit product cost of 39.93 $/GJ under optimum conditions. Finally, based on the findings of the environmental impact analysis, the designed system in cogeneration mode was able to mitigate CO 2 emissions by 1173 kg/h. • Parabolic trough solar collectors are coupled with thermochemical hydrogen production. • Nanoparticles are used to enhance thermal performance of solar loop. • Improvement of 3–5% is found with nanoparticles' utilization on overall system. [ABSTRACT FROM AUTHOR]

Recently, research and development on progressive and efficient hydrogen production methods has been paid lots of attention due to carbon-free feature of hydrogen. Application of nanoparticles to enhance an integrated solar-based hydrogen production unit is suggested and investigated in this work. The integrated plant consists of parabolic trough collectors coupled with a Kalina cycle for electricity generation to be consumed in a polymer electrolyte membrane electrolyzer for hydrogen production. The system performance is apprised for nanofluid as the heat transfer media for solar collectors and is compared with the pure basefluid case. Thermal model for parabolic trough collectors as well as thermodynamic models for Kalina cycle and electrolyzer are developed and validated. Also, thermo physical properties of nanofluid is assessed based on volume fraction of the nanoparticles. Parametric analyses are implemented for system performance assessment in which influence of design variables related to solar collectors, nanoparticels as well as the Kalina cycle are appraised. The effect on the hydrogen rate and solar-to-hydrogen exergy efficiency of design variables are comprehensively examined and discussed. According to the obtained results, the η e x , S T H is found to be 9.19% for the case with basefluid (without nanoparticles), whereas it can be improved to 9.63% with employment of 5% volume fraction of CuO nanoparticles. Such an efficiency improvement is due to the increment of hydrogen production from 0.669 kg/h to 0.702 kg/h using CuO-based nanofluid. • Effect of nanoparticles are evaluated in a PTC unit applied for hydrogen production. • Kalina cycle and PEM electrolyzer is used for electricity and hydrogen production. • Thermal and exergetic evaluations are carried out for performance investigation. • The CuO is found as the best nanoparticle among the three considered types. • Performance enhancement of around 5% is found with nanoparticle incorporation. [ABSTRACT FROM AUTHOR]

Waste incineration is a potent technique, that deals with the waste generated in a sustainable way to properly manage and reduce the generated waste and produce useful energy simultaneously. However, the waste-to-electrical efficiency of incineration plants is less (20–22) % because of the high moisture content of waste and flue gas heat losses. In the present study, a tri-generation system consisting of a solar parabolic trough collector integrated with a waste-to-energy plant, a liquefied natural gas (LNG), and a hydrogen production system is proposed and thermodynamically investigated. Parabolic trough collectors serve as a secondary heating source to the steam coming out of the incineration boiler. The useful heat collected by the parabolic trough solar field is provided to the fluid exiting the incineration boiler and entering into the steam turbine to improve the steam condition, while LNG is vaporized by the energy of exhaust flue gas and produces power for the PEM electrolyzer. Waste-to-energy incineration facility is capable of operating with a feed rate of 350 tons/day, producing 6.3 MW of power at an inlet temperature of 400 °C of the turbine. However, the net power produced is increased to 7.72 MW with increase in turbine inlet temperature to 515 °C. Results of the study conclude that the energetic and the exergetic efficiencies of the incineration plant are found to be 27.93 % and 26.51 %, respectively. In addition, both the first and second law efficiencies are observed as 21.51 % and 25.74 %, respectively, while the rate of hydrogen production is 7.72 kg/h. The cumulative exergy destruction rate of the system is 29.3 MW and the WtE boiler shares the maximum portion (58.14 %) of the exergy destruction. • Sustainable approach to simultaneously manage the waste along with useful outputs. • A novel solar integrated waste-to-energy plant for performance enhancement is proposed. • Power, regasified LNG, hydrogen and fresh water are produced concurrently. • Waste heat recovery sufficiently improves the system performance. [ABSTRACT FROM AUTHOR]

Photocatalysis, a promising semiconductor-based technology activated by free and eternal solar energy, has great potential for addressing environmental remediation and energy conversion challenges. Concentrated solar power (CSP) technologies, namely parabolic trough reflectors, solar power towers, parabolic dish reflectors and linear Fresnel reflectors, exhibited excellent feasibility for boosting solar-driven photocatalytic processes. Based on the structural characteristics of CSP technologies, the CSP-based photocatalytic reactors could be divided into concentrated types and non/low-concentrated types. This academic review comprehensively investigated the integration of CSP technology in photocatalysis, emphasizing the feasibility of sunlight as an ideal energy source. Additionally, considering the optimal light irradiance and reaction temperature demands for achieving efficient photocatalytic processes, the significance of introducing CSP into solar light-driven photocatalytic reactions was highlighted. Moreover, the current challenges that exist in CSP-based photoreactors were identified, and potential solutions were proposed accordingly. This work hopes to provide some references for the future study of CSP-based photocatalytic reactors under the theme of sustainable development. [ABSTRACT FROM AUTHOR]

The modernization, efficiency, and decarbonization of the energy supply systems are among the new challenges to be faced in the coming decades to achieve the targets and objectives dictated by European strategic policies. Despite the countless benefits related to renewable energy sources (RES) integration, this brings key challenges to the power system, such as the risk of imbalance between energy generation and demand, sudden changes in flows in transmission lines with a need for expensive and time-consuming upgrades, and the withdrawal of conventional generation systems with consequent demands for new solutions and innovation to support grid services. A potential solution to limit the huge intermittence and fluctuation in power generation from RES is Concentrated Solar Power (CSP) technology integrated with thermal energy storage. The aim of this paper is to discuss the potential benefits related to the use of CSP technology by presenting innovative industrial solutions developed in the Italian SOLARGRID Project, namely the hybridization of CSP–PV systems and the solar thermo-electric system developed by MAGALDI, the parabolic trough collector of Eni, and the new linear Fresnel reflector configuration of IDEA S.r.l. These plant and component solutions are developed for improving the technical performance of CSP technology and reducing the levelized cost of electricity, thereby fostering an effective and massive deployment and encouraging the creation of new business models. [ABSTRACT FROM AUTHOR]

Platinum (Pt) nanoparticles decorated titanium dioxide (Pt/TiO 2) is considered a multifaceted catalyst owing to its wide applicability from photo to thermo-catalysis, as compared to other engineered materials i.e., noble metals supported metal oxide. In this context, the present article provides an in-depth discussion for application of Pt 2.5 /TiO 2 for photocatalytic hydrogen (H 2) production under stimulated laboratory (indoor) and natural sunlight (outdoor) condition. It demonstrated the promising method for utilising the light and heat of full solar energy spectrum in tandem with photocatalyst (photo-thermocatalysis) to create hydrogen from waste water. However, its underlying mechanism remains elusive and contentious. The discussion is covered in more details to address the effects of various factors on its performance, including physicochemical characteristics of as-synthesized photocatalyst (e.g., optical absorptivity, morphology, and surface functionalities), water splitting evaluation parameters (e.g., catalyst dose, concentration of sacrificial donors, effect of various sacrificial donors, and illumination sources), and underlying mechanisms. The as-synthesized Pt 2.5 /TiO 2 photocatalyst have shown promising hydrogen production rate of 9 mmol h−1 and exhibited unprecedented stability of 24h using Na 2 S/Na 2 SO 3 as sacrificial agent. This study will aid in the search for stable photocatalysts to recover hydrogen from sulphide wastewater. [Display omitted] • Pt 2.5 /TiO 2 photocatalyst used for photocatalytic (PC) and photothermal H 2 production. • Sulphides based donor was screened for photo-thermocatalytic (PTC) H 2 production. • HER of 9 (PC) and 5.5 (PTC) mmols.h−1 obtained with Pt 2.5 /TiO 2 – S2−/SO 3 2− system. • Photolysis of S2−/SO 3 2− shuttle showed HER of 4.2 (PC) and 3.1 (PTC) mmols.h−1. • Pt 2.5 /TiO 2 catalyst exhibited stability of 24 h for water splitting reaction. [ABSTRACT FROM AUTHOR]

The catalyst packed bed structure plays an important role in the promising solar-driven catalyst packed bed based thermochemical hydrogen production systems. However, corresponding accurate yet efficient numerical methods for characterizing and optimizing the catalyst packed bed structure as well as the whole complex solar-driven thermochemical process is still urgently needed. In this paper, a novel three-dimensional comprehensive model is proposed for the hydrogen production of methanol steam reforming reaction (MSRR) in parabolic trough solar receiver-reactors (PTSRR). A relatively realistic porosity distribution obtained by the discrete element method was combined with the optical-thermal-chemical coupling model. The proposed model was validated, proved to improve the accuracy of numerical predictions in a more efficient way. Moreover, it was effectively applied to tune the overall energy flow of the complex optical-thermal-chemical process of PTSRR-MSRRs for better performance, by optimizing the catalyst packed bed structure in aspects of catalyst sizes and packing methods. The results revealed that single packed beds of larger catalyst particles show better performance within the selected catalyst size range. The radial layered packing method of larger particle-to-particle diameter ratios can bring higher energy conversion efficiency and lower flow resistance, as compared to the single packing method and fully mixed packing method. This study could provide an efficient numerical modelling method and significant guidance for other similar solar-driven thermochemical applications of catalyst packed beds. • A novel time-saving optical-thermal-chemical CFD model is proposed for PTSRR-MSRRs. • A relatively more realistic porosity distribution can be coupled into CFD by DEM. • It has advantages of both the porous media model and the particle-resolved model. • It can efficiently study different catalyst particle characteristics and packed beds. • The layered composite packing method is recommended for better performance. [ABSTRACT FROM AUTHOR]

In this paper, a parabolic trough humidifying solar collector-based solar still (PHSC-SS) is proposed. Its purpose is to apply some important performance improvement techniques to the flat plate humidifying solar collector-based solar still (flat plate HSC-SS), to significantly improve overall system performance. These included the use of parabolic trough solar concentrators and the design of humidifying solar collectors from evacuated tube collectors. The results reveal that, unlike flat plate HSC-SS, which must operate with a turbulent airflow regime to achieve optimum overall performance, PHSC-SS must operate with a laminar airflow regime and high inlet and outlet temperatures of air (at least 55 °C and less than 100 °C, at atmospheric pressure) in the heat collector element. For 900 W/m2 of incident solar irradiance, 2 m2 of solar collector area, and 0,00042 kg/s of air flow rate, the maximum energy efficiency, exergy efficiency and daily freshwater productivity of PHSCSS were found to be 68,12%, 14,87% and 1,697 kg/h, respectively. Whereas for the same incident solar irradiance and solar collector area, and 0,1 kg/s of air flow rate, those of the flat plat HSC-SS were 72,9%, 1,12%, and between 1,07 - 2,923 kg/h (for inlet and outlet temperatures of air less than 30 °C, at atmospheric pressure), respectively. Although in some extreme cases freshwater productivity of flat plate HSC-SS can be higher than that of PHSC-SS, it should be noted that laminar airflow regime confers great advantages to PHSC-SS. These are higher air temperatures at condenser inlet (which ease water condensation process), no need of an auxiliary cooling device (needed in the flat plate HSC-SS), less mechanical vibrations of system, reduced condenser size, and less energy consumed by air blowers. Furthermore, the upper limit of the PHSC-SS is a PHSC-SS that operates without air flow, but rather by vaporization of water droplets at boiling point from absorber, followed by their suction to condenser, similarly to a flash evaporation. [ABSTRACT FROM AUTHOR]

A small-scale solar parabolic trough collector system coupled with a jacketed vessel was designed and evaluated for its performance and quality of the products manufactured in it. The prototype having a 7.026 m2 aperture and 88.38° rim angle was installed in Mehsana, Gujarat, India. The study was conducted in May–June 2022 at different flow rates of sigma therm-k. The useful heat rate ranged from 567.82 W to 861.25 W. The daily average thermal efficiency was obtained in the range of 9.81–14.61% and maximum thermal efficiency achieved during the milk trials was 31.51%. Similarly, maximum absorber temperature achieved during stagnation was 193.4°C and during absorber fluid flow condition was 146.5°C. The maximum convective heat transfer coefficient of 49.5 W/m2 K was calculated at Reynold number 1822 and Nusselt number 24.12. It was found that the quality parameters of manufactured milk products were at par with domestic food safety standards. Direct normal irradiance was found to be the most influencing factor followed by the initial milk load. The present system is a potential substitute for various small-scale Indian traditional heat-desiccated milk products, where higher thermal efficiency is not the primary requirement and emphasis is more on the importance of ease of operation. [ABSTRACT FROM AUTHOR]