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.

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.

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 Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: results from the EFEU campaign

2007 ◽  
Vol 7 (4) ◽  
pp. 12657-12686 ◽  
Author(s):  
K. Hungershöfer ◽  
K. Zeromskiene ◽  
Y. Iinuma ◽  
G. Helas ◽  
J. Trentmann ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Absorption Efficiency ◽  
Max Planck ◽  
Fresh Biomass ◽  
Biomass Burning Aerosol ◽  
Smoke Chamber ◽  
The Impact ◽  
Mass Absorption Efficiency

Abstract. A better characterisation of the optical properties of biomass burning aerosol as a function of the burning conditions is required in order to quantify their effects on climate and atmospheric chemistry. Controlled laboratory combustion experiments with different fuel types were carried out at the combustion facility of the Max Planck Institute for Chemistry (Mainz, Germany) as part of the 'Impact of Vegetation Fires on the Composition and Circulation of the Atmosphere' (EFEU) project. Using the measured size distributions as well as mass scattering and absorption efficiencies, Mie calculations provided mean effective refractive indices of 1.60−0.010i and 1.56−0.010i (λ=0.55 μm) for smoke particles emitted from the combustion of savanna grass and an African hardwood (musasa), respectively. The relatively low imaginary parts suggest that the light-absorbing carbon of the investigated fresh biomass burning aerosol is only partly graphitized, resulting in strongly scattering and less absorbing particles. While the observed variability in mass scattering efficiencies was consistent with changes in particle size, the changes in the mass absorption efficiency can only be explained, if the chemical composition of the particles varies with combustion conditions.

Physical a priori solar radiation pressure models for GNSS satellites with the focus on BDS

2021 ◽  
Author(s):  
Bingbing Duan ◽  
Urs Hugentobler ◽  
Inga Selmke ◽  
Stefan Marz
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Thermal Radiation ◽  
Radiation Pressure ◽  
Total Mass ◽  
A Priori ◽  
Solar Radiation Pressure ◽  
The Other ◽  
Time Range ◽  
Satellite Attitude

<p>A physical a priori box-wing solar radiation pressure (SRP) model is widely used by most analysis centers for Galileo and QZSS (Quasi-Zenith Satellite System) satellites, complemented by an ECOM or ECOM2 (Empirical CODE Orbit Model) model. For the other constellations, for instance GPS and GLONASS satellites, optical properties of satellite surfaces are not publicly available, especially for GPS Block IIF and GLONASS satellites. By fixing satellite surface areas and total mass to the values from some unpublished documents, we estimate satellite surface optical properties based on true GNSS measurements covering long time periods (typically this should be longer than a full beta angle time range to reduce correlations between parameters). Meanwhile, various physical effects are considered, such as yaw bias, radiator emission and thermal radiation of solar panels. We find that yaw bias of GPS Block IIA and IIR satellites does not dominate the Y-bias, it is likely that heat generated in the satellite is radiated from louvers or heat pipes on the Y side of the satellite. It is also noted that the ECOM Y0 estimates of both GPS and GLONASS satellites show clear anomaly during eclipse seasons. This indicates that the radiator emission is present when the satellite crosses shadows. Since satellite attitude during eclipse seasons could be different from the nominal yaw, potential radiator effect in the –X surface could be wrongly absorbed by the ECOM Y0 as well. By considering all the estimated parameters in an a priori model we observe clear improvement in satellite orbits, especially for GLONASS satellites. China’s Beidou-3 satellites are now providing PNT (positioning, navigation and timing) service globally. Satellite attitude, dimensions and total mass are publicly available. Also, the absorption optical properties of each satellite surface are given. With all this information, we estimate the other optical properties of Beidou satellites considering similar yaw bias, radiator and thermal radiation effects as those in GPS and GLONASS satellites.</p>

scholarly journals Modelling the Optical Properties of Soot Particles under Various Aging Conditions

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 86
Author(s):  
Kangwei Li ◽  
Mingming Yan ◽  
Jiandong Shen ◽  
Xin Zhang ◽  
Chunmei Geng ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Species ◽  
Absorption Efficiency ◽  
Optical Characteristics ◽  
Core Shell ◽  
Mixing State ◽  
Coating Materials ◽  
Soot Particles ◽  
The Core ◽  
Aging Conditions

As atmospheric fresh soot particles age, they become coated with other chemical species. This transforms their physicochemical properties and affects their optical characteristics, which is of great importance to air quality, the environment and climate change. One of the predominantly occurring states of soot particles in the ambient environment is the core-shell mixing state. In this study, we used the core-shell model to calculate the optical absorption, scattering and extinction efficiency, absorption proportion and absorption exponent of coated soot particles. We then investigated the effects of different core sizes (D0), incident wavelengths (λ), coating materials and coating thicknesses on these optical characteristics. Absorption efficiency and absorption proportion of soot particles decreased as the coating became thicker, at core sizes of D0 = 20, 50 and 100 nm and λ = 405, 532 and 781 nm, regardless of the type of coating material. As the coating thickness increased, the absorption exponent (β) of inorganic-coated soot particles tended to rise and then fall, while the β value of organic-coated soot particles kept increasing. Our results advance our scientific understanding of the interaction of optical properties with chemical composition, mixing state, and aging processes of soot particles in the atmosphere.

scholarly journals Effect of Solar Radiation on the Optical Properties and Molecular Composition of Laboratory Proxies of Atmospheric Brown Carbon

2014 ◽  
Vol 48 (17) ◽  
pp. 10217-10226 ◽  
Author(s):  
Hyun Ji (Julie) Lee ◽  
Paige Kuuipo Aiona ◽  
Alexander Laskin ◽  
Julia Laskin ◽  
Sergey A. Nizkorodov
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Molecular Composition ◽  
Brown Carbon

scholarly journals Aerosol–Cloud Closure Study on Cloud Optical Properties using Remotely Piloted Aircraft Measurements during a BACCHUS Field Campaign in Cyprus

2019 ◽  
Author(s):  
Radiance Calmer ◽  
Gregory C. Roberts ◽  
Kevin J. Sanchez ◽  
Jean Sciare ◽  
Karine Sellegri ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Shortwave Radiation ◽  
Cloud Base ◽  
Field Campaign ◽  
Aerosol Cloud ◽  
Remotely Piloted Aircraft ◽  
Aerosol Cloud Interactions ◽  
The Impact ◽  
Adiabatic Case

Abstract. In the framework of the EU-FP7 BACCHUS project, an intensive field campaign was performed in Cyprus (2015/03). Remotely Piloted Aircraft System (RPAS), ground-based instruments, and remote-sensing observations were operating in parallel to provide an integrated characterization of aerosol-cloud interactions. Remotely Piloted Aircraft (RPA) were equipped with a 5-hole probe, pyranometers, pressure, temperature and humidity sensors, and measured updraft velocity at cloud base and cloud optical properties of a stratocumulus layer. Ground-based measurements of dry aerosol size distributions and cloud condensation nuclei spectra, and RPA observations of vertical wind velocity and meteorological state parameters are used here to initialize an Aerosol–Cloud Parcel Model (ACPM) and compare the in situ observations of cloud optical properties measured by the RPA to those simulated in the ACPM. Two different cases are studied with the ACPM, including an adiabatic case and an entrainment case, in which the in-cloud temperature profile from RPA is taken into account. Adiabatic ACPM simulation yields cloud droplet number concentrations at cloud base (ca. 400 cm−3) that are similar to those derived from a Hoppel minimum analysis. Cloud optical properties have been inferred using the transmitted fraction of shortwave radiation profile measured by downwelling and upwelling pyranometers mounted on a RPA, and the observed transmitted fraction of solar radiation is then compared to simulations from the ACPM. ACPM simulations and RPA observations show better agreement when associated with entrainment compared to that of an adiabatic case. The mean difference between observed and adiabatic profiles of transmitted fraction of solar radiation is 0.12, while this difference is only 0.03 between observed and entrainment profiles. A sensitivity calculation is then conducted to quantify the relative impacts of two-fold changes in aerosol concentration, and updraft velocity to highlight the importance of accounting for the impact of entrainment in deriving cloud optical properties, as well as the ability of RPAs to leverage ground-based observations for studying aerosol–cloud interactions.

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