Investigation of nanofluids circulating in a volumetric solar receiver

2020 ◽  
pp. 1-39
Author(s):  
Emanuele Zanetti ◽  
Simone Dugaria ◽  
Francesca Biscaglia ◽  
Filippo Agresti ◽  
Laura Fedele ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Ad Hoc ◽  
Low Cost ◽  
Absorption Efficiency ◽  
Limited Information ◽  
Carbon Nanohorns ◽  
Novel Approach ◽  
Experimental Apparatus ◽  
Single Wall Carbon Nanohorns

Abstract Single-Wall-Carbon-Nanohorns (SWCNHs) based nanofluids have been proven to be promising media for the direct absorption of solar radiation due to their favourable optical properties and potential low cost. Still, their stability in real working conditions is an open issue because they have been studied mainly under stagnant conditions while limited information is available on the performance of these nanofluids during circulation in real systems. In the present work, the optical behaviour of SWCNHs based nanofluids has been investigated with the aim of detecting possible effects of circulation and exposure to radiation, avoiding other effects such as thermal instability. An ad-hoc experimental apparatus has been realized to check the stability of the circulating fluids in-situ using a novel approach based on the use of pyranometers. Three suspensions are tested, two are surfactant-stabilized and one is based on pre-oxidised and functionalised SWCNHs. Efficiency values higher than 90 % were measured for more than 65 hours of circulation. The effects of fluid circulation and exposure to solar radiation have been addressed, finding that the absorption efficiency decreases during tests due to the degradation of the optical properties and the nanofluid circulation is the main responsible for such degradation.

Large Scale and Low Cost Production of Pristine and Oxidized Single Wall Carbon Nanohorns as Material for Hydrogen Storage

2012 ◽  
Vol 4 (2) ◽  
pp. 160-164 ◽  
Author(s):  
Cesare Pagura ◽  
Simona Barison ◽  
Cecilia Mortalò ◽  
Nicola Comisso ◽  
Mauro Schiavon
Keyword(s):  
Hydrogen Storage ◽  
Large Scale ◽  
Low Cost ◽  
Single Wall Carbon ◽  
Carbon Nanohorns ◽  
Single Wall Carbon Nanohorns

scholarly journals Анализ оптических свойств однородных металлических, окисных наночастиц и двухслойных наночастиц с металлическим ядром и окисной оболочкой с целью эффективного поглощения солнечной радиации

2019 ◽  
Vol 126 (3) ◽  
pp. 374
Author(s):  
Л.Г. Астафьева ◽  
В.К. Пустовалов ◽  
В. Фритче
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Absorption Efficiency ◽  
Nickel Titanium ◽  
Substantial Contribution ◽  
Oxide Shell ◽  
Spectral Interval ◽  
Nanoparticle Radius ◽  
Spectral Coefficients ◽  
Molybdenum Nanoparticles

AbstractProblems related to using nanoparticles for absorption of solar radiation and photothermal nanotechnologies are now being actively studied. The efficiency of using nanoparticles as photothermal agents for solar energy is determined by their spectral optical properties. We performed computer simulation of optical properties of homogeneous metal (nickel, titanium, and molybdenum) nanoparticles and their oxides, along with nanoparticles consisting of a metal core and an oxide shell, with radii in the range from 50 to 100 nm in the spectral interval between 200 and 2500 nm. The influence of nanoparticle radius, the type of metal and its oxide on spectral coefficients of efficiency absorption ( K _abs) and scattering ( K _sca) of radiation by nanoparticles is investigated. The type of nanoparticles suitable for absorption of solar radiation was chosen based on a comparative analysis of the wavelength dependences of absorption efficiency coefficients K _abs, intensity of solar radiation I _ S , and parameter P _1 = K _abs/ K _sca. Spherical double–layer nanoparticles consisting of nickel or titanium core and oxide shells with a radius of 75 or 100 nm can be used in the spectral interval from 200 to 2500 nm for efficient absorption of solar radiation. These results are a substantial contribution to the investigation of optical properties of nanoparticles that can be used in systems of thermal energy.

scholarly journals In-line measurement of absorbed solar irradiance using nanofluids

2021 ◽  
Vol 2116 (1) ◽  
pp. 012118
Author(s):  
E Zanetti ◽  
A Berto ◽  
M Meneghetti ◽  
D Del Col
Keyword(s):  
Solar Radiation ◽  
Solar Irradiance ◽  
Absorption Rate ◽  
Optical Behaviour ◽  
Carbon Nanohorns ◽  
Novel Technique ◽  
Line Measurement ◽  
Combined Use ◽  
Single Wall Carbon Nanohorns ◽  
Solar Receiver

Abstract In this paper a novel technique for the in-line evaluation of the absorption rate of solar radiation by nanofluids in a volumetric solar receiver is presented. This method allows to experimentally investigate the optical behaviour of a nanofluid when circulating in a volumetric solar receiver under non-concentrated solar irradiance and it is based on the combined use of pyranometers. This technique is used in the present work to study the absorption capability of a Single-Wall-Carbon-NanoHorns (SWCNHs) based nanofluid. From the experiments, it can be seen that after some hours of circulation, the absorption rate of the nanofluid decreases, due to a loss of nanoparticles in the suspension.

Using Low Temperature, Cost-effective and Green Methods to Carbon Nanohorn Synthesis

2019 ◽  
Vol 9 (2) ◽  
pp. 157-160
Author(s):  
Ali Hasani
Keyword(s):  
Laser Ablation ◽  
Melting Point ◽  
Palm Olein ◽  
Arc Discharge ◽  
Low Cost ◽  
The Other ◽  
High Yield ◽  
Reaction Field ◽  
Carbon Nanohorns ◽  
Graphite Rod

Background: Laser ablation method has high-yield and pure SWCNHs. On the other hand, arc discharge methods have low-cost production of SWCNHs. However, these techniques have more desirable features, they need special expertness to use high power laser or high current discharge that either of them produces very high temperature. As for the researches, the temperatures of these techniques are higher than 4727°C to vaporize the graphite. So, to become aware of the advantages of SWCNHs, it is necessary to find a new way to synthesize SWCNHs at a lower temperature. In other words, reaction field can be expandable at a moderate temperature. This paper reports a new way to synthesize SWCNHs at an extremely reduced temperature. Methods: According to this study, the role of N2 is the protection of the copper holder supporting the graphite rod by increasing heat transfer from the holder. After the current of 70 A was supplied to the system, the temperature of graphite rod was raised to 1600°C. It is obvious that this temperature is somehow higher than the melting point of palladium, 1555°C, and much lower than graphite melting point, 3497°C. Results: Based on the results, there are transitional precursors simultaneous with the SWCNHs. This composition can be created by distortion of the primary SWCNTs at the higher temperature. Subsequently, each SWCNTs have a tendency to be broken into individual horns. With increasing the concentration of the free horns, bud-like SWCNHs can be produced. Moreover, there are individual horns almost separated from the mass of single wall carbon nanohorns. This structure is not common in SWCNHs synthesized by the usual method such as arc discharge or laser ablation. Through these regular techniques, SWCNHs are synthesized as cumulative particles with diameters about 30-150 nm. Conclusion: A simple heating is needed for SWCNTs transformation to SWCNHs with the presence of palladium as catalyst. The well-thought-out mechanism for this transformation is that SWCNTs were initially changed to highly curled shape, and after that were formed into small independent horns. The other rout to synthesize SWCNHs is the pyrolysis of palm olein at 950°C with the assistance of zinc nitrate and ferrocene. Palm olein was used as a promising, bio-renewable and inexpensive carbon source for the production of carbon nanohorns.

scholarly journals UV-A Treatment of ZrO2 Thin Films Fabricated by Environmental Friendlier Water-Based Solution Processing: Structural and Optical Studies

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 821
Author(s):  
Aneeqa Bashir ◽  
Mehwish Farooq ◽  
Abdul Malik ◽  
Shahzad Naseem ◽  
Arshad Saleem Bhatti
Keyword(s):  
Optical Properties ◽  
Low Cost ◽  
Annealed Film ◽  
Optical Transmittance ◽  
Amorphous Structure ◽  
Solution Processing ◽  
Vis Spectroscopy ◽  
Water Based ◽  
Free Films ◽  
Quartz Substrates

An environmentally friendlier solution processing has been introduced to fabricate zirconium oxide (ZrO2) films on quartz substrates, using spin coating of simple water-based solution. The films cured with UV-A = 330 nm for different times (40, 80, 120 min) were investigated for structural and optical properties and compared with thermally annealed film (at 350 °C). XRD and Raman spectroscopy showed amorphous structure in all the samples with no significant phase transformation with UV-A exposure. AFM microscopy showed smooth and crack free films with surface roughness ≤2 nm that reduced with UV-A exposure. Ultraviolet-visible (UV–Vis) spectroscopy demonstrated optical transmittance ≥88% and energy band gap variations as 4.52–4.70 eV. Optical constants were found from spectroscopic ellipsometry (SE). The refractive index (n) values, measured at 470 nm increased from 1.73 to 2.74 as the UV-A exposure prolonged indicating densification and decreasing porosity of the films. The extinction coefficient k decreased from 0.32 to 0.19 indicating reduced optical losses in the films under the UV-A exposure. The photoluminescence (PL) spectra exhibited more pronounced UV emissions which grew intense with UV-A exposure thereby improving the film quality. It is concluded that UV-A irradiation can significantly enhance the optical properties of ZrO2 films with minimal changes induced in the structure as compared to thermally treated film. Moreover, the present work indicates that water-based solution processing has the potential to produce high-quality ZrO2 films for low cost and environmental friendlier technologies. The work also highlights the use of UV-A radiations as an alternate to high temperature thermal annealing for improved quality.

scholarly journals Optimal design of the solar tracking system of parabolic trough concentrating collectors

2020 ◽  
Vol 15 (4) ◽  
pp. 613-619
Author(s):  
Li Kong ◽  
Yunpeng Zhang ◽  
Zhijian Lin ◽  
Zhongzhu Qiu ◽  
Chunying Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Radiation ◽  
Tracking System ◽  
Low Cost ◽  
Parabolic Trough ◽  
The North ◽  
Tracking Mode ◽  
Solar Tracking ◽  
East West

Abstract The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking > north-south Earth’s axis tracking > north-south tilt tracking (β = 15°) > north-south tilt tracking (β = 45) > north-south horizontal tracking > east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

Effect of Functional Groups at Hole Edges on Cisplatin Release from Inside Single-Wall Carbon Nanohorns

2006 ◽  
Vol 110 (11) ◽  
pp. 5773-5778 ◽  
Author(s):  
Kumiko Ajima ◽  
Masako Yudasaka ◽  
Alan Maigné, ◽  
Jin Miyawaki ◽  
Sumio Iijima
Keyword(s):  
Functional Groups ◽  
Single Wall Carbon ◽  
Carbon Nanohorns ◽  
Single Wall Carbon Nanohorns

scholarly journals Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

2010 ◽  
Vol 10 (12) ◽  
pp. 5391-5408 ◽  
Author(s):  
J. Jung ◽  
Y. J. Kim ◽  
K. Y. Lee ◽  
M. G. -Cayetano ◽  
T. Batmunkh ◽  
...  
Keyword(s):  
Optical Properties ◽  
Long Range ◽  
Atmospheric Chemistry ◽  
Light Attenuation ◽  
Measurement Data ◽  
Absorption Efficiency ◽  
Asian Dust ◽  
Urban Site ◽  
Long Range Transport ◽  
Range Transport

Abstract. As a part of the IGAC (International Global Atmospheric Chemistry) Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57° N, 126.94° E) in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC) ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (babs) from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, σabs (=babs/EC) at 550 nm was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m2 g−1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m2 g−1. Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA) with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP) events. Satellite aerosol optical thickness (AOT) and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

scholarly journals Optimal Design Strategy of a Solar Reflector Combining Photovoltaic Panels to Improve Electricity Output: A Case Study in Calgary, Canada

2021 ◽  
Vol 13 (11) ◽  
pp. 6115
Author(s):  
Moon Keun Kim ◽  
Khalid Osman Abdulkadir ◽  
Jiying Liu ◽  
Joon-Ho Choi ◽  
Huiqing Wen
Keyword(s):  
Solar Radiation ◽  
Electricity Generation ◽  
Low Cost ◽  
Design Strategy ◽  
Numerical Approach ◽  
Optimal Shape ◽  
Energy Technology ◽  
Experimental Database ◽  
Pv Panel

This study explores the combination of photovoltaic (PV) panels with a reflector mounted on a building to improve electricity generation. Globally, PV panels have been widely used as a renewable energy technology. In order to obtain more solar irradiance and improve electricity output, this study presents an advanced strategy of a reflector combining PV panels mounted on a building in Calgary, Canada. Based on an experimental database of solar irradiances, the simulation presents an optimal shape designed and tilt angles of the reflector and consequently improves solar radiation gain and electricity outputs. Polished aluminum is selected as the reflector material, and the shape and angle are designed to minimize the interruption of direct solar radiation. The numerical approach demonstrates the improvement in performance using a PV panel tilted at 30°, 45°, 60°, and 75° and a reflector, tilted at 15.5° or allowed to be tilted flexibly. A reflector tilted at 15.5° can improve solar radiation gains, of the panel, by nearly 5.5–9.2% at lower tilt angles and 14.1–21.1% at higher tilt angles. Furthermore, the flexibly adjusted reflector can improve solar radiation gains on the PV panel, by nearly 12–15.6% at lower tilt angles and 20–26.5% at higher tilt angles. A reflector tilted at 15.5° improves the panel’s output electricity on average by 4–8% with the PV panel tilted at 30° and 45° respectively and 12–19 % with the PV panel tilted at 60° and 75°, annually. Moreover, a reflector that can be flexibly tilted improves electricity output on average by 9–12% with the PV panel tilted at 30° and 45° and 17–23% with the PV panel tilted at 60° and 75°. Therefore, the utilization of a reflector improves the performance of the PV panel while incurring a relatively low cost.

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