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A comprehensive assessment of alternative absorber-exchanger designs for hybrid PVT-water collectors
摘要： In this paper, 26 alternative absorber-exchanger designs for hybrid PV-Thermal (PVT) solar collectors are proposed and compared against a reference-case, commercial sheet-and-tube PVT collector. The collectors involve different geometric design features based on the conventional sheet-and-tube configuration, and also on a newer flat-box structure constructed from alternative polymeric materials with the aim of maintaining or even improving heat transfer and overall (thermal and electrical) performance while achieving reductions in the overall weight and cost of the collectors. The main contributions of this research include: (i) the development and validation of a detailed 3-D computational finite-element model of the proposed PVT collector designs involving multi-physics processes (heat transfer, fluid dynamics and solid mechanics); (ii) results from comparative techno-economic analyses of the proposed PVT designs; and, (iii) further insights from thermal stress and structural deformation analyses of the proposed collectors, which are crucial for ensuring long lifetimes and especially important in the case of polymeric collectors. The results show that, in general, the flat-box designs (characterised by a thin absorber plate) are not sensitive to the flow-channel size or construction material, at least within the range of investigation. A PVT collector featuring a polycarbonate (PC) flat-box design with 3 × 2 mm rectangular channels appears to be a particularly promising alternative to commercial PVT collectors, achieving a slightly improved thermal performance compared to the reference case (with a 4% higher optical efficiency and 15% lower linear heat-loss coefficient), while also lowering the weight (by around 9%) and investment cost (by about 21%) of the collector. The structural analysis shows that the maximum von Mises stress experienced in the absorber-exchanger of the PC flat-box collector is considerably lower than that in the copper sheet-and-tube collector (< 13% vs. 64% of the material’s yield stress), which is attributed to the larger thermal expansion of the PC absorber-exchanger, that leads to lower stresses. Therefore, the proposed PC flat-box design is not expected to suffer higher strains than the commercially-available PVT collector.
关键词： Cost savings,Hybrid PVT collector,Solar energy,Efficiency,Absorber-exchanger,Structural analysis
更新于2025-09-10 09:29:36
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Apparent delay analysis for a flat-plate solar field model designed for control purposes
摘要： This study presents an analysis of the effect of the transport delay which occurs in solar flat-plate collector fields and how to include its behavior in dynamic models suitable for control purposes. This investigation has been carried out using simplified models based on dynamic energy balances and models based on step response methods and experimental tests. The solar flat-plate collector field encompasses parallel absorber pipes intertwined with pipelines which act as several first-order plus dead time systems in parallel. The effect is an apparent delay observed at the outlet temperature that must be included in the dynamic model in order to reduce the error between the real measurement and the model prediction. The main contribution of this paper is the procedure to evaluate the apparent delay to obtain adequate dynamic models aimed to be used for control purposes.
关键词： Solar energy,Dynamic simulation,Bilinear model
更新于2025-09-10 09:29:36
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Deploying solar energy with community choice aggregation: A carbon fee model
摘要： This article investigates solar photovoltaic deployment through community choice aggregation programs. A case study of a solar energy program facilitated through a public energy council in Southeastern Ohio is highlighted, which used a ‘carbon fee’ model to collect a 0.2 cents per kilowatt hour incremental fee above the standard aggregation rate. This premium funds the development of behind-the-meter solar installations, and may serve as an exemplary approach for other aggregation programs to deploy solar.
关键词： solar energy,electricity,local governance,Ohio,Community choice aggregation
更新于2025-09-10 09:29:36
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Large Errors from Assuming Equivalent DC and High-Frequency Electrical Characteristics in Metal–Multiple-Insulator–Metal Diodes
摘要： Metal-insulator-metal (MIM) tunnel diodes are essential for ultra-high speed rectification. We review an erroneous method for distributing DC voltage drops across multiple insulator layers that is used in all the published literature on these devices. It has resulted in large errors between designed and fabricated multi-insulator diodes. For multi-insulator MIM diodes, voltage division is dependent on both tunneling resistances and oxide capacitances. We demonstrate that correct voltage division at DC is determined by the rectification resistance, as opposed to the commonly used capacitive voltage division. We find that DC characteristics of multi-insulator diodes cannot be used to predict high frequency behavior.
关键词： solar energy,infrared,optical rectenna,Metal/insulator/metal (MIM) diode,tunneling diodes
更新于2025-09-10 09:29:36
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Reference Module in Earth Systems and Environmental Sciences || Solar Distillation and Drying☆
摘要： Fresh water demand is persistently increasing as populations around the world keep growing and as existing fresh water reserves keep declining due to consumption and pollution. Energy demand is also continually increasing due to relentless global industrialization. Fossil fuels remain the primary sources of energy for most of the world; however, their reserves are dwindling, production is peaking, and consumption is harming the environment. Renewable energy sources are continually replenished by cosmic forces and can be used to produce sustainable and useful forms of energy with minimum environmental impact.
关键词： Solar Drying,Solar Distillation,Renewable Energy,Desalination,Solar Energy
更新于2025-09-09 09:28:46
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Reference Module in Earth Systems and Environmental Sciences || Solar Energy in Buildings☆
摘要： Solar Energy can be utilized in many ways (e.g., photovoltaics, solar–thermal–electrical systems, solar ponds, and biomass conversion), but in the current chapter only applications associated with covering the heating and cooling requirements of buildings will be discussed. These applications require low or medium -temperature heat and include water heating, either for domestic hot water systems or swimming pools, space heating, and possibly also space cooling.
关键词： Net Zero Energy Buildings,Economics,Passive Systems,Design Methods,Thermal Behavior of Buildings,Buildings,Solar Energy,Solar Collectors,Space Heating and Cooling Systems,Hot Water Systems
更新于2025-09-09 09:28:46
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Experimental analysis and numerical validation of the solar Dish/Stirling system connected to the electric grid
摘要： The use of solar-powered Stirling engines to convert thermal energy into electricity is a promising and renewable technological solution that can contribute to reducing dependence on fossil fuels for electricity generation. Unfortunately, the lack of experimental performance data and operating parameters for this type of technology limits its detailed characterization, difficult its modeling and design and consequently its utilization. This paper aims to validate the mathematical model of the Dish/Stirling system previously published by Mendoza et al. (2017) with the TRINUM system, installed at the Federal University of Itajubá-Brazil. For nominal conditions, the Dish/Stirling system generates an electric power of 1.00 kW at a solar irradiation of 725 W/m2 with a system overall efficiency of 17.6%. The results show that for solar irradiance values between 520 and 950 W/m2 the experimental tests and the results of the mathematical modeling do not present considerable differences, obtaining an electric power of 1,089 kWe and an efficiency of 17.98%, which represents deviations in the range of 2% to 12%.
关键词： Energy Conversion,Solar Concentrator,Numerical validation,Stirling Engine,Solar Energy,Thermal analysis
更新于2025-09-09 09:28:46
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Energy and exergy performance assessment of a novel solar-based integrated system with hydrogen production
摘要： In this study, a new solar power assisted multigeneration system designed and thermodynamically analyzed. In this system, it is designed to perform heating, cooling, drying, hydrogen and power generation with a single energy input. The proposed study consists of seven sub-parts which are namely parabolic dish solar collector, Rankine cycle, organic Rankine cycle, PEM-electrolyzer, double effect absorption cooling, dryer and heat pump. The effects of varying reference temperature, solar irradiation, input and output pressure of high-pressure turbine and pinch point temperature heat recovery steam generator are investigated on the energetic and exergetic performance of integration system. Thermodynamic analysis result outputs show that the energy and exergy performance of overall study are computed as 48.19% and 43.57%, respectively. Moreover, the highest rate of irreversibility has the parabolic dish collector with 24,750 kW, while the lowest rate of irreversibility is calculated as 5745 kW in dryer. In addition, the main contribution of this study is that the solar-assisted multi-generation systems have good potential in terms of energy and exergy efficiency.
关键词： Exergy,Energy,Solar energy,Heating-cooling,Hydrogen,Multigeneration
更新于2025-09-09 09:28:46
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[ASME ASME 2015 Conference on Smart Materials, Adaptive Structures and Intelligent Systems - Colorado Springs, Colorado, USA (Monday 21 September 2015)] Volume 2: Integrated System Design and Implementation; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting - A Sub-Surface Model of Solar Power for Distributed Marine Sensor Systems
摘要： The capabilities of distributed sensor systems, such as wildlife telemetry tags, could be significantly enhanced through the application of energy harvesting. For animal telemetry systems, supplemental energy would allow for longer tag deployments, wherein more data could be collected, enhancing our temporal and spatial comprehension of the hosts activities and/or environments. There are various transduction methods that could be employed for energy harvesting in aquatic environments. Photovoltaic elements have not been widely deployed in the sub-surface marine environments despite a significant potential. In addition to wildlife telemetry systems, photovoltaic energy harvesting systems could also serve as a means of energy supply for Autonomous Underwater Vehicles (AUVs), as well as submersible buoys for oceanographic data collection. Until now, the use of photovoltaic cells for underwater energy harvesting has generally been disregarded as a viable energy source in this arena, with only one company currently offering solar modules integrated with marine telemetry tags. In this article, we develop a model of power available from photovoltaic cells deployed in a sub-surface marine environment. We cover the methods and tools used to estimate solar energy at depth, including the effects of: latitude and longitude, reflected solar energy off of the oceans surface, solar irradiance lost due to the absorption and turbidity of the sea water, cloud cover, etc. We present the availability of this solar energy source in the context of the energy requirements of some of these sensor systems, such as marine bio-loggers. Additionally, we apply our model to simulate the energy harvested on specific marine species in which high fidelity depth information is known. We also apply our model to simulate solar cells at certain depths under the ocean to gain a general understanding of the solar energy available at these depths.
关键词： sub-surface marine environment,photovoltaic cells,marine telemetry,solar energy,energy harvesting
更新于2025-09-09 09:28:46
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Nanoscale Materials in Water Purification || Photocatalysis of Graphene and Carbon Nitride-Based Functional Carbon Quantum Dots
摘要： Day by day, global energy demands increase due to the rapid consumption of depleting fossil fuels and environmental pollution. This has led to the search for materials capable of both energy conversion and elimination of environmental pollutants through the aid of renewable solar energy. This is a promising approach for meeting future energy requirements and eliminating environmental pollutants. In this pursuit, semiconductor photocatalysts have immense potential for solving both energy and environmental issues. To date, numerous semiconductor materials have been explored, including those of metal oxides, chalcogenides, borates, titanates, tungstates, vanadates, zirconates, oxyhalides, and metal-based interstitial compounds. However, the majority of these suffer from limitations such as complex synthesis procedures, limited light absorption range due to their wide band gap, high cost, and toxicity-related issues. Over the past decade, carbon-based nanomaterials have gained attention in the field of photocatalysis. Many recent articles have placed emphasis upon metal-free carbon-based photocatalytic systems for degradation of organic pollutants and hydrogen production from water splitting. The prime merit of these nanomaterials is that they originate from naturally abundant constituent elements such as carbon, nitrogen, and oxygen, making them more economical than their metal-based counterparts. Most reported carbon-based photocatalysts have tunable band gap energies, enhancing their optical absorption range. Band gap energy can be tuned by varying synthesis conditions and precursors, resulting in the formation of nanomaterials with different morphologies. The preparation procedures for most carbon-based nanomaterials are less complex than those of metal-based materials.
关键词： water splitting,energy conversion,semiconductor photocatalysts,graphene,carbon nitride,quantum dots,carbon-based nanomaterials,hydrogen production,solar energy,environmental pollutants,photocatalysis
更新于2025-09-09 09:28:46