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Magnetically separable nanocomposites based on ZnO and their applications in photocatalytic processes: A review
摘要： Among the most challenging problems that human beings appear to face are depleting energy sources and increasing environmental pollutions. Heterogeneous photocatalytic processes are the most rewarding technology to generate renewable energy and degrade environmental pollutants. In these processes, semiconductors are used as photocatalysts. ZnO is a widely used photocatalyst, because of its strong oxidation ability, cost effectiveness, non-toxicity, versatility in synthesis, abundance in nature, and ease of crystallization. However, pure ZnO has some drawbacks, due to its wide band gap, poor solar-light utilization, and rapid recombination of the photoinduced charge carriers. Modification of ZnO using different strategies including coupling with narrow band gap semiconductors, noble metal deposition, surface sensitization by organic dyes, and elemental doping can easily address these shortcomings. In addition, separation of photocatalysts from the treated systems limits their broad applications. Incorporation of photocatalysts in magnetic materials will help their recycling using external magnetic field. This combination leads to a new generation of photocatalysts, known as magnetically separable photocatalysts. The present review provides helpful insights into preparation of magnetically separable photocatalysts based on ZnO and their applications for degradations of different pollutants.
关键词： water pollutants,Magnetic photocatalysts,solar-energy conversion,ZnO-based nanocomposites
更新于2025-09-23 15:21:01
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Selected methods of converting solar energy into electricity - comparative analysis
摘要： This article presents selected methods of converting solar energy into electricity: photovoltaic cells (PV), converters which use photon-enhanced thermionic emission (PETE), and near-field enhanced thermionic energy conversion systems (NETEC). PETE and NETEC systems are innovative solutions that use the thermionic emission phenomenon and can replace photovoltaic generation of electricity. We did a comparative analysis of such issues as: structure, principle of operation, - efficiency. working A comparison of these parameters is shown in the graphs and summarized in the table. Based on the analysis, we have drawn conclusions about previous achievements and development perspectives in the field of converting methods.
关键词： solar energy,PETE,NETEC,conversion efficiency,thermionic emission,photovoltaic cells
更新于2025-09-23 15:21:01
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[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Application of Nanofluid-Based Direct Absorption Solar Collector in Once-Through Multistage Flash Desalination System
摘要： Multistage ?ash (MSF) desalination technique is one of the simplest of thermal desalination methods which requires thermal energy in order to desalinate seawater. This thermal energy can be provided by solar energy harnessed by a direct absorption solar collector (DASC) in which a nano?uid while ?owing through the collector absorbs the incident irradiation directly and gets heated to higher temperatures. These collectors are having a relatively higher thermal ef?ciency (10% higher) as compared to conventional surface-absorption-based solar collectors. In this study, a direct absorption solar collector (DASC) has been used as a heat source for multistage ?ash (MSF) desalination system having once-through (OT) con?guration, and these two systems are coupled using a counter?ow type heat exchanger. This direct absorption collector is replaced by surface-absorption-based collector in order to prevent the degradation of thermal performance of surface-absorption-based collector due to high salinity of seawater as in the present case seawater ?ows through heat exchanger and is getting heated by the nano?uid ?owing through direct absorption collector. The aim of the present study is to evaluate the thermal performance of the combined system which is represented by a quantity known as gained output ratio (GOR). The thermal performance or ef?ciency of the solar collector depends upon various parameters such as thickness of nano?uid layer inside DASC (H), length of the collector (L), particle volume fraction of nanoparticles (fv), and incident solar energy (q) which will affect the performance of the MSF system also. Hence, the performance of the combined system will be evaluated as a function of the collector parameters mentioned above. The gained output ratio is also evaluated as a function of brine rejection temperature (Tb) and feed seawater temperature (Tf) which are parameters associated with the MSF desalination system. The fresh water production rate (m?d) has also been evaluated as a function of the abovementioned parameters related to the collector and MSF system. A numerical model has been prepared to solve the temperature pro?le of the DASC system which is solved using ?nite difference implicit method (FDM) with the help of MATLAB. The numerical model for MSF desalination system is also prepared and solved in MATLAB.
关键词： Nano?uid,Once-through,Solar energy,Desalination,Multistage ?ash
更新于2025-09-23 15:21:01
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Optimization of solar photovoltaic efficiency using angular inclination: Effect on surface temperature distribution
摘要： Temperature distribution over the surface of a solar photovoltaic (PV) panel is essential as over heating lowers the efficiency of the PV module. There have been multiple solutions towards cooling the PV surface during extremely hot sunshine. The mechanism is envisaged to be expensive to construct and maintain. In this research the PV panel was inclined at various degree to determine the best inclination that would allow convective cooling. It was observed that at an inclination of 45o, the convective cooling from surrounding wind was able to regulate the surface temperature. Hence, the sinusoidal trend of thermal heating was distorted significantly-signifying that the convective wind was able to mitigate the PV surface heating.
关键词： temperature,energy,renewable energy,solar energy,solar
更新于2025-09-23 15:19:57
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Optimization of solar photovoltaic efficiency using angular inclination: Effect on voltage output
摘要： The physical optimization processes of maximizing the solar photovoltaic (PV) panel via the angular adjustment of PV inclination to the sun were examined. The efficiency may vary within geographic locations. In this study, the measured dataset of a location in the tropical region of Nigeria was examined with the inclination ranging from 0o to 45 o. It was observed that at 30 o in the south –east direction yielded a more stable result that is essential basically for the stability of the solid state content of the PV panel. Though there were spikes of higher voltage in the 30 o, it is recommended that PV users in the region to adopt 30 o to enhance efficiency and longevity of the PV panel.
关键词： energy,renewable energy,solar energy,solar,voltage output
更新于2025-09-23 15:19:57
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Thermodynamic efficiency comparison between thermal and electric storage for photovoltaic-driven chilling system
摘要： Faced with the ever-increasing pressures from climate change and environmental pollution, stand-alone photovoltaic (PV) power generation is promising in providing electricity to the air conditioners. However, the solar energy is usually susceptible to the weather changes, making the power supply unreliable. To mitigate the e?ects caused by the solar intermittency, additional energy storage bu?er is necessary. In this paper, stand-alone PV chilling systems with water tank thermal energy storage (TES) and battery electric energy storage (EES) strategies are quantitatively compared by evaluating the thermodynamic e?ciency, respectively. A chiller model is ?rstly built, based on which the initial steady states are derived. Secondly, the EES and TES system models are built based on the compressor speed control strategy and refrigeration cycle model. The resulting chilled water temperature ?uctuation curves in TES and EES PV chillers are subsequently obtained. Quantitative comparative results in this paper are threefold. i) The average chilled water temperature of the TES strategy is 11.08% lower than that in the EES strategy; ii) The average cooling energy amount stored in the TES strategy is 43.6% larger than that in the EES strategy, indicating that the chilled water tank has a better energy storage potential in the given PV chiller system; iii) The water volume of TES is optimized to derive the maximum cooling energy storage rate which is 76.92% larger than that in the EES system.
关键词： Chilling system,Thermal energy storage,Electrical energy storage,Solar energy
更新于2025-09-23 15:19:57
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Concentrated photovoltaic and thermal system application for fresh water production
摘要： This study was conducted to investigate the performance of Concentrated Photovoltaic/Thermal system (CPV/T) coupled with direct contact membrane distillation (DCMD) for saline water desalination. A numerical heat and mass flux model was constructed to investigate the feasibility of freshwater production. The average electrical efficiency was found to be about 18%, while thermal efficiency increased to an average of 25% and the total efficiency reached an average of 71%. The CPV/T efficiency with the cooling loop reached 19.26% at the peak time of the process. Eventually, the DCMD produced 3 kg/m2/h of fresh water and consumed thermal energy of about 9200 kJ/kg water. Moreover, the water mass flux decreased from 3 L/m2/h to 1.8 L/m2/h in a nonlinear manner. When the gain output ratio (GOR) of the system reaches 2.6 efficiency value or greater, the water outlet temperature from the CPV/T can increase along with the water permeate flux produced by the coupled system. In contrast, if the temperature of the outlet water from the CPV/T system is low, the feed water temperature in the heat exchanger also decreases. As a result, a significant decrease is observed in the feed inlet temperature of the DCMD module.
关键词： Membrane distillation,Solar desalination,Concentrated flat plate solar photovoltaic–thermal,Solar energy,Water desalination
更新于2025-09-23 15:19:57
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Analysing consequence of solar irradiance on amorphous silicon solar cell in variable underwater environments
摘要： Harvesting underwater Solar energy using photovoltaic (PV) technology leads to an innovative approach to utilize it in monitoring various underwater sensors, devices, or other autonomous systems using modern-day power electronics. Another huge advantage of placing PV cells underwater comes from the fact that the water itself can provide cooling and cleaning for the cells. Such advantages come with many challenges and constraints due to the underwater spectral change and decrease in Solar radiation with an increase in water depth. In this work, an experimental set-up has been realized to create an underwater environment and further characterized in the indoor environment using the Solar simulator. Moreover, the transfer of Solar radiation through water and the performance of amorphous silicon Solar cell underwater up to 0.2 m has been analysed in changing underwater environments. This investigation shows a better understanding of solar radiation underwater and the amorphous silicon solar cell underwater at shallow depths with considering the water depth up to 0.2 m, salinity 3.5%, total dissolved salts, and other impurities affecting the solar radiation and the performance of amorphous silicon Solar cell in underwater conditions. In addition to that, the maximum power output Pmax of amorphous silicon Solar cell is 0.0367 W at 0.2 m in the case of DI water. In contrast, in real seawater and artificial seawater with 3.5% salinity, it shows 0.0337 W and 0.0327 W, respectively.
关键词： water salinity,amorphous silicon Solar cell,photovoltaic (PV) technology,underwater Solar energy,Solar radiation,PDMS (polydimethylsiloxane)
更新于2025-09-23 15:19:57
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Experimental and theoretical analysis of hybrid concentrated photovoltaic/thermal system using parabolic trough collector
摘要： In the current work, a hybrid concentrated photovoltaic thermal system was designed and coupled with a parabolic trough collector and investigated theoretically and experimentally for combined heat and power output. In the design, a photovoltaic module was mounted on a flat surface of parabolic trough absorber tube having semi cylindrical shape. A provision was made to cool photovoltaic panel from both the surfaces by flowing water through the absorber tube as well as the annulus of between absorber tube and glass cover. The model was developed using first law of the thermodynamics and then validated using experimental data generated through the fabricated setup. During the experimentation, the annulus flow rate was varied from 0.008 kg/s, 0.017 kg/s and 0.025 kg/s and inner flow rate was varied from 0.075 kg/s, 0.083 kg/s and 0.091 kg/s. The field testing results showed the mean overall efficiency of system obtained as 61.42%, 64.61% and 66.36% for inner tube flow rate of 0.075 kg/s, 0.083 kg/s and 0.091 kg/s respectively for annulus flow rate of 0.008 kg/s. The theoretical results of hybrid system obtained from the simulation are in good agreement with the experimental data. In the end environmental cost analysis was also carried out for the proposed system.
关键词： Hybrid system,Concentrated Photovoltaic/thermal,Parabolic trough collector,Renewable energy,Solar energy
更新于2025-09-23 15:19:57
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Direct vs Delayed Triplet Energy Transfer from Organic Semiconductors to Quantum Dots and Implications for Luminescent Harvesting of Triplet Excitons
摘要： Hybrid inorganic-organic materials such as quantum dots (QDs) coupled with organic semiconductors have a wide range of optoelectronic applications, taking advantage of the respective materials strengths. A key area of investigation in such systems is the transfer of triplet exciton states to and from QDs, which has potential applications in the luminescent harvesting of triplet excitons generated by singlet fission, in photocatalysis and photochemical upconversion. While the transfer of energy from QDs to the triplet state of organic semiconductors has been intensely studied in recent years, the mechanism and materials parameters controlling the reverse process, triplet transfer to QDs have not been well investigated. Here, through a combination of steady state and time-resolved optical spectroscopy we study the mechanism and energetic dependence of triplet energy transfer from an organic ligand (TIPS-tetracene carboxylic acid) to PbS QDs. Over and energetic range spanning from exothermic (-0.3 eV) to endothermic (+0.1 eV) triplet energy transfer we find that the triplet energy transfer to the QD occurs through a single step process with a clear energy dependence that is consistent with an electron exchange mechanism as described by Marcus-Hush theory. In contrast, the reverse process, energy transfer from the QD to the triplet state of the ligand does not show any energy dependence in the studied energy range, interestingly a delayed formation of the triplet state occurs relative to the quantum dots decay. Based on the energetic dependence of triplet energy transfer we also suggest design criteria for future materials systems where triplet excitons from organic semiconductors are harvested via QDs, for instance in light emitting structures or the harvesting of triplet excitons generated via singlet fission.
关键词： singlet fission,quantum dots,solar energy,photon multiplication,triplet energy transfer
更新于2025-09-23 15:19:57