scholarly journals Spectral Radiative Properties of a Liquid n-Octane Droplet in the Midinfrared Region

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Liang Zhao ◽  
Chaoyu Jing ◽  
Yu Jin ◽  
Jiangping Chen ◽  
Ke Yin ◽  
...  
Keyword(s):  
Refractive Index ◽  
Wavelength Range ◽  
Optical Constants ◽  
Absorption Efficiency ◽  
Efficiency Factor ◽  
Radiative Properties ◽  
Droplet Radius ◽  
Scattering Efficiency ◽  
Scattering Coefficients ◽  
Increasing Temperature

The optical constants of a liquid hydrocarbon such as liquid n-octane are basic material properties that may be used to evaluate their thermal radiation transfer capabilities. In this study, the ellipsometry method was used to measure the optical constants of liquid n-octane in the midinfrared wavelength range of 2.0–16.0 μm at temperatures of 20, 50, and 80°C. Experimental analyses indicate the significant effect of temperature on the refractive index, although it has little effect on the absorption index. With increasing temperature, the refractive index shows a linear decrease, and reduced density leads to weaker absorption intensities. The radiative properties of n-octane droplets, including the absorption and scattering efficiency factors of single droplets with droplet radii r = 10, 20, 50, and 100 μm and the absorption and scattering coefficients in a droplets-air system of droplet volume fractions fv = 2%, 3%, and 4%, were calculated using Mie theory. The numerical results indicate that, with increasing temperature, the absorption efficiency factor slightly decreases, and the variation trend of the scattering efficiency factor is more complicated. With increasing droplet radius, the absorption efficiency factor increases within the studied wavelength range, except for certain absorption peaks, but the scattering efficiency factor tends to decrease. While the absorption is greater, the scattering is weaker for a given droplet radius. With an increasing volume fraction of n-octane droplets, the absorption and scattering coefficients increase linearly within the studied wavelength range.

Radiative Heating of Semi-Transparent Diesel Fuel Droplets

2004 ◽  
Vol 126 (1) ◽  
pp. 105-109 ◽  
Author(s):  
S. S. Sazhin ◽  
W. A. Abdelghaffar ◽  
E. M. Sazhina ◽  
S. V. Mikhalovsky ◽  
S. T. Meikle ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Diesel Fuel ◽  
Absorption Efficiency ◽  
Efficiency Factor ◽  
Radiative Heating ◽  
Droplet Radius ◽  
Polynomial Functions ◽  
Gas Temperature ◽  
Fuel Droplets ◽  
Temperature Ranges

Absorption spectra of four types of diesel fuel are studied experimentally in the range between 0.2 μm and 6 μm. The ageing process of fuels is simulated by prolonged boiling. The average absorption efficiency factor of droplets is assumed to be proportional to ardb, where rd is the droplet radius, and a and b are polynomial functions of external gas temperature. Explicit expressions for a and b are derived for diesel fuel droplets in various realistic droplet radii and external gas temperature ranges for all four types of fuel.

scholarly journals The Influence of Chemical Component Distribution on the Radiometric Properties of Particle Aggregates

2019 ◽  
Vol 9 (7) ◽  
pp. 1501 ◽  
Author(s):  
Yizhan Chai ◽  
Zhen Yang ◽  
Yuanyuan Duan
Keyword(s):  
Refractive Index ◽  
Minor Component ◽  
Absorption Efficiency ◽  
Chemical Component ◽  
Spherical Particles ◽  
Chemical Components ◽  
Scattering Efficiency ◽  
Component Distribution ◽  
Extinction Efficiency ◽  
Particle Aggregates

The radiometric properties, including the extinction efficiency, absorption efficiency, scattering efficiency, and asymmetric parameter values of particle aggregates consisting of multiple chemical components are critical in industry and nature. This article aims to analyze the influence of chemical component distribution on these radiometric properties. The particle aggregates are generated by a diffusion-limited aggregate method by which spherical particles are stuck together randomly. The particle aggregates have two components with a major component of a fixed refractive index and a minor component of a changed refractive index. The radiometric properties are calculated using a multi-sphere T-matrix (MSTM) method for particle aggregates with different particle radii and with refractive indices, distributions of components, and volume fractions of the minor component. The results show that the chemical component distribution influences the radiometric properties of the particle aggregate. Evenly spreading the strong absorptive minor component into each particle, compared to concentrating it in a few particles, can raise the absorption efficiency, reduce the scattering efficiency, and ultimately reduce the extinction efficiency of the aggregate. For aggregates with major and minor components in different particles, a similar effect is shown when spreading the minor component particles evenly in the aggregate relative to gathering them in one part of the aggregate.

scholarly journals A detailed characterization of the Saharan dust collected during the Fennec Campaign in 2011: <i>in situ</i> ground-based and laboratory measurements

2017 ◽  
Author(s):  
Adriana Rocha-Lima ◽  
J. Vanderlei Martins ◽  
Lorraine A. Remer ◽  
Martin Todd ◽  
John H. Marsham ◽  
...  
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
Mineral Dust ◽  
Chemical Properties ◽  
Single Scattering ◽  
Absorption Efficiency ◽  
Saharan Dust ◽  
Low Density ◽  
Scattering Coefficients

Abstract. Millions of tons of mineral dust are lifted by the wind from arid surfaces and transported around the globe every year. The physical and chemical properties of the mineral dust are needed to better constrain remote sensing observations and are of fundamental importance for the understanding of dust atmospheric processes. Ground-based in situ measurements and in situ filter collection of Saharan dust were obtained during the Fennec campaign in the central Sahara in 2011. This paper presents results of the absorption and scattering coefficients, and hence, single scattering albedo (SSA), of the Saharan dust measured in real time during the last period of the campaign, and subsequent laboratory analysis of the dust samples collected in two supersites, SS1 and SS2, in Algeria and in Mauritania, respectively. The samples were taken to the laboratory where their size and aspect ratio distributions, mean chemical composition, spectral mass absorption efficiency and spectral imaginary refractive index were obtained from the ultraviolet (UV) to the near infrared (NIR) wavelengths. At SS1 in Algeria, the time series of the scattering coefficients during the period of the campaign show dust events exceeding 3500 Mm−1 and a relatively high mean SSA of 0.995 at 670 nm was observed at this site. The laboratory results show for the fine distributions in both sites a spectral dependence of the imaginary part of the refractive index Im(m) with a bow-like shape, with increased absorption in ultraviolet and also in the shortwave infrared. The same signature was not observed, however, in the mixed size distribution in Algeria. Im(m) was found to range from 0.011 to 0.001i for dust collected in Algeria and 0.008 to 0.002i for dust collected in Mauritania over the wavelength range of 350–2500 nm. Differences in the mean elemental composition of the dust collected in the supersites in Algeria and in Mauritania and between fine and mixed modes distributions were observed from EDXRF measurements, although those differences cannot be used to explain the optical properties variability between the samples. Finally, particles with low-density typically larger than 10 μm in diameter were found in some of the samples collected at the supersite in Mauritania, but these low-density particles were not observed in Algeria.

Absorption/Scattering Coefficients and Scattering Phase Functions in Reticulated Porous Ceramics

1996 ◽  
Vol 118 (1) ◽  
pp. 79-87 ◽  
Author(s):  
T. J. Hendricks ◽  
J. R. Howell
Keyword(s):  
Wavelength Range ◽  
Phase Function ◽  
Theoretical Models ◽  
Porous Ceramics ◽  
Physical Structure ◽  
Radiative Properties ◽  
Discrete Ordinates ◽  
Scattering Coefficients ◽  
Scattering Phase ◽  
Phase Functions

Spectral absorption and scattering coefficients and spectral scattering phase functions have been derived for partially stabilized zirconia (PS ZrO2) and oxide-bonded silicon carbide (OB SiC) reticulated porous ceramics (RPCs) across the wavelength range 0.4–5.0 μm. These spectral radiative properties were investigated and quantified for 10 ppi (pores/inch), 20 ppi, and 65 ppi materials. Radiative properties were recovered from spectral hemispherical reflectance and transmittance measurements using inverse analysis techniques based upon discrete ordinates radiative models. Two dual-parameter phase functions were investigated for these materials: one based on the physical structure of reticulated porous ceramics and the other a modified Henyey–Greenstein phase function. The modified Henyey–Greenstein phase function provided the most consistent spectral radiative properties. PS ZrO2 radiative properties exhibited strongly spectrally dependent behavior across the wavelength range studied. OB SiC radiative properties exhibited radiative behavior that was relatively independent of wavelength across the wavelength spectrum studied. OB SiC also demonstrated consistently higher absorption coefficients than PS ZrO2 at all wavelengths. Spectral scattering albedos of PS ZrO2 were discovered to be in the range 0.81–0.999 and increased as ppi rating increased, while those for OB Sic were lower in the range 0.55–0.888 and decreased as ppi rating increased. The average extinction efficiencies for 0.4–5.0 μm were discovered to be 1.45 for Ps ZrO2 and 1.70 for OB SiC. Extinction coefficients were discovered to correlate well with geometric optics theoretical models and electromagnetic wave/fiber interaction models based on independent scattering and absorption mechanisms.

Study the Effect of Heat Treatment and Pressure on some the Optical Properties of the Pure PVA Nano Polymer

2021 ◽  
Vol 900 ◽  
pp. 16-25
Author(s):  
Tabarak Mohammed Awad ◽  
May A.S. Mohammed
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Polyvinyl Alcohol ◽  
Complex Dielectric Constant ◽  
Different Temperatures ◽  
German Origin ◽  
Increasing Temperature

In this study, some optical properties were studied of the pure vinyl polyvinyl alcohol (PVA) nanopolymer (German origin). Under the influence of different temperatures and pressures of PVA. Where 25 samples were prepared for the purpose of conducting the research. Which studied the study of these samples was done by recording the absorbance and transmittance spectra of the wavelengths (200-900) nm. From them, absorbance, transmittance, reflectivity, absorption coefficient, refractive index, extinction coefficient, complex dielectric constant were calculated. At different temperatures (25,40, 80, 120, 160)°C. And with different pressures within the range (7.5,8,8.5,9,9.5) MPa. The results are that the permeability of the polymer (PVA) at different temperatures for each pressure decreases with increasing temperature, and that all other calculated optical properties increase with increasing temperature.

Optical Diagnostics and Radiative Properties of Simulated Soot Agglomerates

1991 ◽  
Vol 113 (4) ◽  
pp. 953-958 ◽  
Author(s):  
J. C. Ku ◽  
K.-H. Shim
Keyword(s):  
Optical Diagnostics ◽  
Forward Scattering ◽  
Radiative Properties ◽  
Weak Effect ◽  
Radiative Transport ◽  
Fractal Aggregates ◽  
Scattering Coefficients ◽  
Primary Particles ◽  
Accurate Relation ◽  
Number Of Particles

The effect of agglomeration on the optical diagnostics and radiative properties of simulated soot agglomerates is investigated, using results from the Jones solution. It is found that agglomeration has a very strong effect on scattering, but only a weak effect on extinction (≅ absorption). An accurate relation has been developed, based on near-forward scattering coefficients, for inferring the number of primary particles in soot agglomerates. General models for both total and differential scattering coefficients have also been established. These results are in general agreement with those predicted for fractal aggregates having a large number of particles. Because of the effect of agglomeration, scattering may not be negligible in treating radiative transport from soot agglomerates.

Sign in / Sign up

Export Citation Format

Share Document