This study investigates the proficiency of employing solar energy in a novel setup geared towards simultaneous production of desalinated water and hydrogen wielding parabolic trough solar collectors ...(prime mover) in three solar radiation approaches; low radiation, high irradiation and no radiation. Targeted for coastal areas, this setup generates electricity using an organic Rankine cycle; utilizing its waste heat, a desalination unit applying humidification and dehumidification processes, yields desalinated water. Subsequently, hydrogen is produced through exploiting a proton exchange membrane electrolyser as a low temperature electrolyser fed by electricity and water. One of the cardinal points of this system is the production of hydrogen by means of electricity and desalinated water obtained from previous stages. With the purpose of determining the efficiency of this setup, a parametric study has been conducted grounded on the effect of important parameters on production rates and different efficiencies. Ensuing, multi-objective optimization is set forth by implementing a genetic algorithm in order to effectuate the optimal design state. The results indicated that the desalination rate in the three solar radiation approaches mentioned are 1.76 kg/s, 1.07 kg/s and 1.36 kg/s, respectively, and the hydrogen production rate are 4.33 g/s, 2.62 g/s and 3.54 g/s, correspondingly.
•Producing desalinated water and hydrogen from seawater using solar energy.•Performing a multi-objective optimization to achieve the highest performance.•Considering low, high, and no solar radiation operational modes during a day.•Producing 4.33, 2.62, and 3.54 g/s of hydrogen for mentioned modes, respectively.•Attaining 81.5%, 27.9% and 50.61% of energy efficiency for mentioned modes, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•For any particular working fluid, there is an optimum mass flow rate which maximizes the collector efficiency.•The highest heat absorption by the collector occurs at different mass flow rates for ...water and CuO nonofluid.•Nanoparticles often enhance the thermal characteristics of the base fluid.•An optimum value of the mass flow rate may be obtained in each individual condition.
Solar water heating is an effective method for heat demands in domestic applications. Solar collector is a main component of any solar water heating system. In this work, the effect of CuO–water nanofluid, as the working fluid, on the performance and the efficiency of a flat-plate solar collector is investigated experimentally. The volume fraction of nanoparticles is set to 0.4% and the mean particle dimension is kept constant at 40nm. The working fluid mass flow rate is varied from 1 to 3kg/min. The experiments are conducted in Mashhad, Iran with the latitude of 36.19°. The experimental results reveal that utilizing the nanofluid increases the collector efficiency in comparison to water as an absorbing medium. The nanofluid with mass flow rate of 1kg/min increases the collector efficiency about 21.8%. For any particular working fluid, there is an optimum mass flow rate which maximizes the collector efficiency. Adding nanoparticles to a base fluid produces a nanofluid which has enhanced thermal characteristics compared with its base fluid.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The present work demonstrates prototypes of highly efficient flat plate solar thermal collectors prototypes based on transparent insulation materials (TIM) technology for efficiency improvement and ...an overheating protection system. The design and optimization of the collectors have been numerically carried out using a previously developed simulation tool based on an in-house software platform (NEST) capable of simulating all the entities constituting the system as a whole and using efficient coupling between the elements. Three design variants for the demonstration have been previously tested under laboratory conditions. These collectors are then mounted on the roof of a hospital building. Their performance is comparatively tested along with a conventional flat plate solar collector, under actual meteorological conditions and during long periods. The energy collected is about 2.5 and 1.4 times higher than standard collectors in winter and spring. Thus, due to the long-term exposure of the collectors, aspects such as reliability, durability, energy performance, and correct functioning of the protection system have been analyzed to improve the detected shortcomings for the future generations of the present design.
•High efficiency, flat plate solar collectors based on TIM installed in demo site.•Energy collected about 2.5 times higher respect standard collector in winter.•Energy collected about 1.4 times higher respect standard collector in spring.•Estimated costs about 30%–40% higher than a conventional flat plate collector.•Overheating protection system must improve reliability to reach commercialization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, an experimental and numerical investigation of eight geometrical configurations of evacuated tube solar collectors was conducted. The configurations were tested simultaneously in ...outdoor installation under the same operational conditions. Parameters such as collector eccentricity, solar concentration, vacuum, collector absorber, and cover tube materials were investigated. The numerical model developed in MATLAB was validated with experimental results. The results show that the eccentricity and the absorptivity of the material of the absorber are the parameters that have the highest influence on the collector performance. Using reflective film in the eccentric solar collector configurations can increase efficiency by 33%. The vacuum presented an efficiency increase variation between 1 and 4% in the eccentric tube collectors. For the concentric collectors configurations, the use of the vacuum between the tubes can reach an increase of 9% in its performance. The eccentricity of the collector using reflective film and vacuum allows an effective solar concentration in the collector absorber and presents a 26% higher efficiency when compared with the concentric collector. The numerical results show that Makrolon can used as a sub for the usual glass cover, and the selection of the solar absorption for the absorber has the highest impact on the collector efficiency. Using steel black chrome for the absorber reached a maximum efficiency of 82%. These results can be used to support the design of future solar collectors.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
With growing interest in the use of solar thermal applications to produce renewable and sustainable energy, coupled with the remarkable progress being made in nanotechnology, many innovative ...solutions have been proposed to improve the performance of solar energy harvesting technologies. Plasmonic nanofluids based on noble metallic nanoparticles are promising media for direct absorption solar collectors, which exploit localized surface plasmon resonance to enhance absorptivity within the solar spectrum. Plasmonic nanofluids can be used to control spectral absorption and scattering efficiencies by tailoring the morphologies of plasmonic nanoparticles. The absorption characteristics can be tuned to match the incident solar radiation, which boosts energy conversion efficiency, even at very low concentrations of nanoparticles. This reduces the collector's pumping power. The spectral absorption characteristics can also be exploited in photovoltaic/thermal systems by increasing the nanofluid transmissivity only in the photovoltaic working bands. This paper presents a comprehensive review of plasmonic nanofluids for solar thermal applications, including the design and development methods of new plasmonic materials. Understanding solar simulator concepts is also crucial for verifying and validating the use of spectral selective plasmonic materials in volumetric absorption solar collectors under normal or high flux irradiance. The optical characteristics of plasmonic nanofluids are reviewed along with the latest developments in conventional and novel materials for various solar thermal applications.
•Plasmonic nanofluids have great potential for direct absorption solar collectors.•Plasmonic nanofluids result in high photothermal conversion efficiencies.•Plasmonic nanoparticles exploit the localized surface plasmon phenomenon.•Absorption of plasmonic nanoparticles within the solar spectrum can be fine-tuned.•Blending different plasmonic nanoparticle morphologies will further boost efficiency.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hydrogels are investigated broadly in flexible sensors which have been applied into wearable electronics. However, further application of hydrogels is restricted by the ambiguity of the sensing ...mechanisms, and the multi-functionalization of flexible sensing systems based on hydrogels in terms of cost, difficulty in integration, and device fabrication remains a challenge, obstructing the specific application scenarios. Herein, cost-effective, structure-specialized and scenario-applicable 3D printing of direct ink writing (DIW) technology fabricated two-dimensional (2D) transition metal carbides (MXenes) bonded hydrogel sensor with excellent strain and temperature sensing performance is developed. Gauge factor (GF) of 5.7 (0 - 191% strain) and high temperature sensitivity (-5.27% °C
) within wide working range (0 - 80 °C) can be achieved. In particular, the corresponding mechanisms are clarified based on finite element analysis and the first use of in situ temperature-dependent Raman technology for hydrogels, and the printed sensor can realize precise temperature indication of shape memory solar array hinge.
Sustainable energy generation is one of the most important challenges facing society today. Solar energy is one of the best sources of renewable energy with minimal environmental impact which offers ...a solution. The present work investigates the heat transfer performance and entropy generation of forced convection through a direct absorption solar collector. The working fluid is Cu–water nanofluid. The simulations focus specifically on the effect of solid volume fraction of nanoparticle and Reynolds number on the mean Nusselt number, mean entropy generation, Bejan number and collector efficiency. Also Isotherms and heatfunction are presented for various solid volume fraction and inertia force. The governing partial differential equations are solved using penalty finite element method with Galerkins weighted residual technique. The results show that both the mean Nusselt number and entropy generation increase as the volume fraction of Cu nanoparticles and Reynolds number increase. The results presented in this study provide a useful source of reference for enhancing the forced convection heat transfer performance while simultaneously reducing the entropy generation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The effect of the riser to header diameter ratio and total cross-sectional area ratio on the flow distribution and thermal performance of flat-plate solar collectors is investigated. An analytical ...model based on the mass and momentum conservation equations is developed to determine the pressure drop and flow distribution in flat plate collectors. A numerical model is also developed to the assess the thermal effects of flow maldistribution. The accuracy of both models is verified against comparison with experimental measurements taken from the open literature. The use of the models is then extended to cover the flow distribution in solar collector networks. It is found that for laminar and turbulent conditions, cross-sectional area ratios and diameter ratios equal or lower than 0.75 and 0.25 respectively, minimize flow nonuniformity and reduce thermal imbalances. The results can be used for design purposes.
•Influence of free flow area parameters on flow maldistribution in flat plate solar collectors is studied.•Tube to header total free flow area ratio and diameter ratio are shown to have a major impact on flow non-uniformity.•Results provide design recommendations for the reduction of flow maldistribution.•Recommended free flow area and diameter ratios apply to both single and networks of solar collectors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•The effects of concentration and collector depth on receiver efficiency are studied.•The uniform temperature can be achieved by the magnetic force convection system.•This system ...improves the receiver efficiency of collectors from ~42.1% to ~57.9%.•This method paves a new avenue to improve receiver efficiency of solar collectors.
The concentration of nanofluids and receiver depth are important factors that significantly affect the efficiency of direct absorption solar collectors. In the current work, the impact of the two factors is investigated using reduced graphene oxide/ethanol glycol nanofluids. The results show uneven temperature distribution in the receiver at high nanofluid concentration or when the receiver is deep. To overcome these issues, a forced convection nanofluid absorption system using α-Fe2O3 magnetic nanoparticles as the nano-rotor, and driven by an external rotating magnetic field, was designed. The mechanism of the new system is compared with the conventional one in detail. The photothermal conversion efficiency of the binary nanofluids (α-Fe2O3–graphene oxide/ethanol glycol nanofluids) in the new system reaches 56.8%, which is 14.5% higher than non-external rotating magnetic field nanofluids, for an RGO content of 0.007 wt%. This enhancement is ascribed to two effects of α-Fe2O3: improving the optical absorption capacity of binary nanofluids and acting as a nano-rotor. The optimum photothermal conversion efficiency is achieved at an RGO/α-Fe2O3 ratio of 3 in the current system.
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IMTLJ, KILJ, KISLJ, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
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•Ultrastable solar nanofluids with broadband photothermal absorption were prepared.•A stabilization technique circumventing any need for free surfactants was developed.•Colloidal ...stability was maintained for 16 months, a new record for solar nanofluids.•Long-term storage, incremental heating, and increased loading tests were conducted.•Nanofluid-specific design vectors were optimized for efficient solar conversion.
Nanofluids used in low-flux direct absorption solar collectors (DASCs) typically encounter critical stability issues due to long-term storage, elevated temperatures, high particle concentrations, and fouling from free surfactants. Here, we developed ultrastable nanofluids, and their properties were used to computationally optimize DASC designs. Broadband photothermal absorption was achieved using citrate- (CIT-) and polyethylene glycol-coated (PEG-) gold nanoparticles, circumventing the need for free surfactants. The nanofluids were subjected to long-term ambient storage, high particle concentrations, and incremental heating to analyze their stability and utility in DASCs. Electrosteric stabilization (PEG + CIT) provided superior colloidal stability and more consistent optical properties; chemical and colloidal stability was verified for 16 months, the longest demonstration of stable nanofluids under ambient storage in the solar literature. Optical measurements of the stabilized solar nanofluids were fed into a DASC optimization model. A constrained generalized pattern search (GPS) algorithm simultaneously maximized collector thermal power-gain and minimized nanoparticle mass loading, while maintaining a collector temperature-gain target. Ultimately, by simultaneously developing ultrastable solar nanofluids, minimizing nanoparticle loading requirements, and maximizing collector thermal power gain, the outcomes from this study are considered significant steps towards deploying efficient and reliable low-flux, nanofluid-based DASCs in field applications.
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