Gaseous Conductivity Study on Silica Aerogel and Its Composite Insulation Materials

2010 ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xiaoze Du ◽  
Xinxin Zhang
Keyword(s):  
Experimental Study ◽  
Atmospheric Pressure ◽  
Silica Aerogel ◽  
Calcium Silicate ◽  
Experimental Results ◽  
Insulation Materials ◽  
Transient Hot Strip ◽  
Hot Strip ◽  
Aerogel Composite ◽  
Micro Level

This paper presented theoretical and experimental study on gaseous conductivity of silica aerogel and it’s composite insulation materials. The samples of silica aerogel, xonotlite-type calcium silicate, xonotlite-aerogel composite and ceramic fibre-aerogel composite insulation materials were prepared firstly. The gaseous conductivities of the prepared samples were measured from 0.045 Pa to atmospheric pressure with the transient hot-strip (THS) method. The gaseous conductivity expressions based on the kinetic theory were then compared with the experimental results. It is shown that both the gaseous conductivity of xonotlite-type calcium silicate and silica aerogel decreases significantly with the drop of pressure. The gaseous conductivity of xonotlite-type calcium silicate reaches to zero at about 100 Pa and the gaseous conductivity of silica aerogel reaches to zero at about 104 Pa. The theoretical gaseous conductivity expressions match well with the experimental results of xonotlite-type calcium silicate and silica aerogel respectively, but do not match with the experimental results for the composite insulation materials. It indicates that the aerogel does not fill the two kinds of composite insulation materials entirely, and some micro level pores still exist in them.

Gaseous Conductivity Study on Silica Aerogel and Its Composite Insulation Materials

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xiaoze Du ◽  
Xinxin Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Silica Aerogel ◽  
Calcium Silicate ◽  
Experimental Results ◽  
Ceramic Fiber ◽  
Insulation Material ◽  
Insulation Materials ◽  
Transient Hot Strip ◽  
Hot Strip ◽  
Aerogel Composite

This paper presents a theoretical and experimental study on gaseous conductivity of silica aerogel and composite insulation materials. First, the insulation material samples (including silica aerogel, xonotlite-type calcium silicate, xonotlite-aerogel composite, and ceramic fiber-aerogel composite) were prepared. Next, the gaseous conductivities of the prepared samples were measured from 0.045 Pa to atmospheric pressure using the transient hot-strip (THS) method. The gaseous conductivity expressions obtained based on the kinetic theory were then compared with the experimental results. It is shown that the gaseous conductivity of both xonotlite-type calcium silicate and silica aerogel decreases significantly with decreasing pressure. The gaseous conductivities of xonotlite-type calcium silicate and silica aerogel reach zero at about 100 Pa and 104 Pa, respectively. The theoretical gaseous conductivity expressions match well with the experimental results of xonotlite-type calcium silicate and silica aerogel but not with the experimental results for the composite insulation materials. This mismatch indicates that the aerogel does not totally fill the original interspace of the xonotlite-type calcium silicate and ceramic fiber in the two kinds of composite insulation materials.

Thermal Radiation in Silica Aerogel and its Composite Insulation Materials

2011 ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xinxin Zhang ◽  
Xiaoze Du
Keyword(s):  
Thermal Radiation ◽  
Extinction Coefficient ◽  
Silica Aerogel ◽  
Extinction Coefficients ◽  
Ceramic Fibre ◽  
Insulation Materials ◽  
Hot Strip ◽  
Aerogel Composite ◽  
Infrared Spectrometer ◽  
Spectral Extinction Coefficient

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.

Experimental Analysis on Thermal Conductivity of Rock

2013 ◽  
Vol 438-439 ◽  
pp. 318-320
Author(s):  
Mei Yan Wang ◽  
Xin Xin Lin ◽  
Zhao Jun Mo ◽  
Lu Lu Pan
Keyword(s):  
Thermal Conductivity ◽  
Experimental Study ◽  
Experimental Analysis ◽  
Rock Stratum ◽  
Transient Hot Strip ◽  
Strip Method ◽  
Hot Strip ◽  
Transient Hot Strip Method ◽  
Thermal Conductivity Of Rock

This paper carried out the experimental study on the thermal conductivity of rock in different depth by transient hot-strip method and the analysis on the reliability of the data. The results show that thermal conductivity of pelitic siltstone has been less affected by the varying versus depth of the rock stratum than tuff, but the thermal conductivity of tuff slightly higher than pelitic siltstone.

scholarly journals Experimental study of the $ \gamma p \rightarrow K^{0}\Sigma^{+}$, $ \gamma n \rightarrow K^{0} \Lambda$, and $ \gamma n \rightarrow K^{0} \Sigma^{0}$ reactions at the Mainz Microtron

2019 ◽  
Vol 55 (11) ◽  
Author(s):  
C. S. Akondi ◽  
K. Bantawa ◽  
D. M. Manley ◽  
S. Abt ◽  
P. Achenbach ◽  
...  
Keyword(s):  
Experimental Study ◽  
Cross Sections ◽  
Differential Cross ◽  
Legendre Polynomials ◽  
Neutral Kaon ◽  
Experimental Results ◽  
Differential Cross Sections ◽  
Theoretical Predictions ◽  
Photoproduction Reactions ◽  
Insight Into

Abstract.This work measured $ \mathrm{d}\sigma/\mathrm{d}\Omega$dσ/dΩ for neutral kaon photoproduction reactions from threshold up to a c.m. energy of 1855MeV, focussing specifically on the $ \gamma p\rightarrow K^0\Sigma^+$γp→K0Σ+, $ \gamma n\rightarrow K^0\Lambda$γn→K0Λ, and $ \gamma n\rightarrow K^0 \Sigma^0$γn→K0Σ0 reactions. Our results for $ \gamma n\rightarrow K^0 \Sigma^0$γn→K0Σ0 are the first-ever measurements for that reaction. These data will provide insight into the properties of $ N^{\ast}$N* resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the $ \pi N$πN channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions.

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