Analytical Monte Carlo Ray Tracing simulation of radiative heat transfer through bimodal fibrous insulations with translucent fibers

Arambakam, R.; Tafreshi, H. Vahedi; Pourdeyhimi, Behnam

doi:10.1016/j.ijheatmasstransfer.2012.07.049

Cited by 24 publications

(8 citation statements)

References 39 publications

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“…Thermal properties of composite nonwovens Arambakam et al (2012) studied the steady-state radiative heat transfer through bimodal fi brous media with translucent fi bres using a Monte Carlo Ray Tracing (MCRT) simulation technique. It was observed that an increase in either fi brediameter dissimilarity or the mass fraction of coarser fi bres resulted in a slight increase in thermal conductivity through the media and thus also a reduced temperature gradient across the thickness of the media.…”

Section: 4mentioning

confidence: 99%

Properties of composite nonwovens

Das

2014

Composite Non-Woven Materials

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Section: 4mentioning

confidence: 99%

Properties of composite nonwovens

Das

2014

Composite Non-Woven Materials

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“…In characterization of optical properties of a scattering particle, three important aspects have to be taken into consideration: complex refractive index of the particle ( N ), particle size relative to the wave length of radiation, which is express as particle size parameter ( x = 2πr/λ), and the wavelength of incident electromagnetic wave (λ). In this respect, for large particles, in which, particle size is much larger than the radiation wavelength ( x ≫ 1), scattering is a reflection process and can be calculated using geometric optic approximation (GOA) . For small particles, irradiated by the electromagnetic wave, whose length is much greater than the size of the particle, the Rayleigh scattering approximations can be used.…”

Section: Introductionmentioning

confidence: 99%

“…In this respect, for large particles, in which, particle size is much larger than the radiation wavelength (x ) 1), scattering is a reflection process and can be calculated using geometric optic approximation (GOA). [8][9][10] For small particles, irradiated by the electromagnetic wave, whose length is much greater than the size of the particle, the Rayleigh scattering approximations can be used. According to Rayleigh's theory, the scattering crosssection in far-field is proportional to x 4 , where, x is the light frequency.…”

Section: Introductionmentioning

confidence: 99%

The relationship between refractive index and optical properties of absorbing nanoparticle

Piri

Shams‐Nateri

Mokhtari

2015

Color Research & Application

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This article represents an analytical formulation for optical properties of absorbing metallic nanoparticles in visible region of electromagnetic spectrum based on Mie theory, in order to find a clear relationship between fundamental characteristics of nanoparticles with their spectral behavior and color coordinate in CIE-LAB color space. Calculations were performed on nanoparticles with various diameters (d 5 50, 100, and 200 nm), as well as complex refractive index with different real (n 5 1.5, 2.0, 2.5, and 3.0) and imaginary (k 5 0.001 and 0.1) parts. Obtained results reveal that scattering phenomena in nanoparticles are strongly linked to the particle size parameter and complex index of refraction. The results indicate that the reflectance and lightness (L*) of nanoparticles increases as a result of increase in their size and real part of complex refractive index and decrease with increasing the imaginary part of complex refractive index. The CIELAB colorimetric system was used for analysis the color of nanoparticles. According to obtained results, all nanoparticles have greenish-blue color, and undergo color change as a result of varying in their size and the complex refractive index.

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“…Earlier investigations of radiative transfer in fibrous media focused mainly on infinitely long fibers with sizes comparable or smaller than the radiation wavelengths (e.g. [19][20][21][22][23][24][25] ) while few studies focused on radiative characteristics of optically large fibers [29][30][31][32][33] . Recent works of Dauvois et al [33] focused on the implementation of the multiple intensities approach in order to study radiative transfer in a felt of fibers applied as insulation in high-temperature systems.…”

Section: Introductionmentioning

confidence: 99%

Radiative characterization of random fibrous media with long cylindrical fibers: Comparison of single- and multi-RTE approaches

Randrianalisoa

Haussener

Baillis

et al. 2017

Journal of Quantitative Spectroscopy and Radiative Transfer

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a b s t r a c tRadiative heat transfer is analyzed in participating media consisting of long cylindrical fibers with a diameter in the limit of geometrical optics. The absorption and scattering coefficients and the scattering phase function of the medium are determined based on the discrete-level medium geometry and optical properties of individual fibers. The fibers are assumed to be randomly oriented and positioned inside the medium. Two approaches are employed: a volume-averaged two-intensity approach referred to as multi-RTE approach and a homogenized single-intensity approach referred to as the single-RTE approach . Both approaches require effective properties, determined using direct Monte Carlo ray tracing techniques. The macroscopic radiative transfer equations (for single intensity or two volume-averaged intensities) with the corresponding effective properties are solved using Monte Carlo techniques and allow for the determination of the radiative flux distribution as well as overall transmittance and reflectance of the medium. The results are compared against predictions by the direct Monte Carlo simulation on the exact morphology. The effects of fiber volume fraction and optical properties on the effective radiative properties and the overall slab radiative characteristics are investigated. The single-RTE approach gives accurate predictions for high porosity fibrous media (porosity about 95%). The multi-RTE approach is recommended for isotropic fibrous media with porosity in the range of 79 −95%.

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Analytical Monte Carlo Ray Tracing simulation of radiative heat transfer through bimodal fibrous insulations with translucent fibers

Cited by 24 publications

References 39 publications

Properties of composite nonwovens

Properties of composite nonwovens

The relationship between refractive index and optical properties of absorbing nanoparticle

Radiative characterization of random fibrous media with long cylindrical fibers: Comparison of single- and multi-RTE approaches

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