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1.
2.
《Measurement》2016
The application of non-intrusive optical devices, such as infrared pyrometers able to measure the temperature of surfaces, makes possible the evaluation of emissivity curve of the tested materials at different temperature values. In this paper the authors propose a methodology for the spectral emissivity measurement by means of a single color pyrometer providing a semi-empirical formula, obtained experimentally at CIRA’s laboratory. The semi-empirical formula allows to know the actual emissivity value of the sample’s surface for whatever emissivity value set up on the pyrometer. The agreement between the experimental emissivity and the emissivity predicted by semi-empirical formula was verified. 相似文献
3.
G. Britto Joseph G. Mageshwaran Jeya Jeevahan R. B. Durai Raj A. Poovannan 《国际自然能源杂志》2019,40(4):388-392
The properties of emissivity (?) and absorptivity (α) of the surface of the material is an essential output for the solar collector. This paper highlights the work based on the RSM design expert, to study the effect of parameters’ temperature and time when the surface is exposed to sunlight and absorbing the properties of emissivity and absorptivity of the material SS 304. The temperature range of the SS 304 varied from 20°C to 356°C for various time intervals from 90 to 1100?h. From this experimental work, it is clearly seen that the emissivity rate increased when the surface is focused onto sunlight beyond the saturated level. The absorptivity of the surface of SS 304 increases till the optimum level and reaches the saturated level. As a result, after the optimum level, emissivity rate of the surface increases, and absorptivity of the surface decreases when it is focused onto sunlight. 相似文献
4.
燃气辐射供暖系统辐射管发射率对室内热环境的影响研究 总被引:2,自引:0,他引:2
在对物理模型合理简化的基础上,对燃气辐射供暖空间温度场的分布进行了模拟,指出辐射管不同发射率对空间温度场的影响,指出提高辐射管黑度可强化燃气辐射供暖技术。 相似文献
5.
Changes in the temperature of nanocrystalline SiC film surface were measured during film growth by direct deposition of carbon and silicon ions onto substrates at ∼800 °С. It has been found that the initial stage of the film growth is characterized by uncontrolled variations of the surface temperature, which are observed for constant values of the deposition parameters. The energy components of the temperature balance on the film surface during its growth under conditions of direct ion deposition are analyzed. It is shown that magnitudes of temperature variations depend on the energy and current density of the deposited ions and on the ratio of the emissivity coefficients of the substrate material and silicon carbide. If this ratio is 1:6, the temperature rise at the initial growth stage reaches 160 °С when using 120 eV ion energy. For ion deposition onto silicon carbide substrates these uncontrolled temperature deviations at the initial stage of film growth were not observed. 相似文献
6.
Olivier Rozenbaum Domingos De Sousa Meneses Patrick Echegut 《International Journal of Thermophysics》2009,30(2):580-590
Thermal and optical properties of ceramics are dependent on radiation scattering and cannot be determined by a knowledge of
their chemical composition alone, as for single crystals. In this paper, extrinsic effects, such as roughness, porosity, and
texture, on the spectral emissivity of alumina ceramics are investigated. Roughness effects have an influence mainly in the
opaque zone; an important porosity dependence and the presence of a critical porosity threshold were observed in the semitransparent
zone. Furthermore, it was shown that two ceramics with similar total porosities, but with different textures, possess radically
different emissivities, showing that grain size, pore size, and spatial repartition of the grains are also crucial for an
understanding of the thermal properties of the ceramics.
This study was performed at CEMTHI laboratory. 相似文献
7.
C. Monte B. Gutschwager S. P. Morozova J. Hollandt 《International Journal of Thermophysics》2009,30(1):203-219
A new experimental facility was realized at the PTB for reduced-background radiation thermometry under vacuum. This facility
serves three purposes: (i) providing traceable calibration of space-based infrared remote-sensing experiments in terms of
radiation temperature from −173 °C to 430 °C and spectral radiance; (ii) meeting the demand of industry to perform radiation
thermometric measurements under vacuum conditions; and (iii) performing spectral emissivity measurements in the range from
0 °C to 430 °C without atmospheric interferences. The general concept of the reduced background calibration facility is to
connect a source chamber with a detector chamber via a liquid nitrogen-cooled beamline. Translation and alignment units in
the source and detector chambers enable the facility to compare and calibrate different sources and detectors under vacuum.
In addition to the source chamber, a liquid nitrogen-cooled reference blackbody and an indium fixed-point blackbody radiator
are connected to the cooled beamline on the radiation side. The radiation from the various sources is measured with a vacuum
infrared standard radiation thermometer (VIRST) and is also imaged on a vacuum Fourier-transform infrared spectrometer (FTIR)
to allow for spectrally resolved measurements of blackbodies and emissivity samples. Determination of the directional spectral
emissivity will be performed in the temperature range from 0 °C to 430 °C for angles from 0° to ±70° with respect to normal
incidence in the wavelength range from 1 μm to 1,000 μm.
References to commercial products are provided for identification purposes only and constitute neither endorsement nor representation
that the item identified is the best available for the stated purpose. 相似文献
8.
Xiaogang Sun Peng Xiao Guibin Yuan Jingmin Dai 《International Journal of Thermophysics》2009,30(1):249-256
The temperatures and emissivities of the metallic thermal protection blanket at (900–1,300) °C are investigated experimentally
by using a multi-wavelength pyrometer. A linear relation between the emissivity and true temperature at different wavelengths
is assumed. Based on this assumption, the true temperatures and spectral emissivities of the metallic thermal protection blanket
at the two temperature measurement points can be calculated simultaneously. Some experimental results for the practical data
processing of measurements performed on the metallic thermal protection blanket show that the difference between the calculated
temperature and the temperature measured by a standard thermocouple is within ± 10°C. 相似文献
9.
V. B. Khromchenko S. N. Mekhontsev L. M. Hanssen 《International Journal of Thermophysics》2009,30(1):9-19
To complement existing water bath blackbodies that now serve as NIST primary standard sources in the temperature range from
15 °C to 75 °C, a gallium fixed-point blackbody has been recently built. The main objectives of the project included creating
an extended-area radiation source with a target emissivity of 0.9999 capable of operating either inside a cryo-vacuum chamber
or in a standard laboratory environment. A minimum aperture diameter of 45 mm is necessary for the calibration of radiometers
with a collimated input geometry or large spot size. This article describes the design and performance evaluation of the gallium
fixed-point blackbody, including the calculation and measurements of directional effective emissivity, estimates of uncertainty
due to the temperature drop across the interface between the pure metal and radiating surfaces, as well as the radiometrically
obtained spatial uniformity of the radiance temperature and the melting plateau stability. Another important test is the measurement
of the cavity reflectance, which was achieved by using total integrated scatter measurements at a laser wavelength of 10.6 μm.
The result allows one to predict the performance under the low-background conditions of a cryo-chamber. Finally, results of
the spectral radiance comparison with the NIST water-bath blackbody are provided. The experimental results are in good agreement
with predicted values and demonstrate the potential of our approach. It is anticipated that, after completion of the characterization,
a similar source operating at the water triple point will be constructed.
Certain commercial equipment, instruments, or material are identified in this paper to specify the experimental procedures
and result adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute
of Standards and Technology, nor is it intended to imply that material or equipment identified are necessarily the best available
for the purpose. 相似文献
10.
In the last years many studies have been carried out on the possible improvements of the in situ thermal conductance measurement; as well known, this has to be derived by recorded values of temperatures and heat fluxes. A big effort has been addressed in the implementation and comparison of different analysis methods. The aim of this paper is to widen the existent literature in the study of the influence of different kinds of input data on the final result. First the problem of analysing input data with significant drift in temperature is considered, adopting both nominal clean and noise affected data. Then the effect due to the presence of the Heat Flux Meter (HFM) on the thermal field of the testing element has been analysed, as well as the possibility of recording HFM surface temperature. These studies are based on Finite Element Method (FEM) simulations; both nominal clean and noise affected data have been considered as input. Finally, a difference in emissivity between the heat flux meter and internal plaster surface has been analysed by means of FEM simulations based on nominal clean data. An overall estimation of the occurred deviations in the different cases is shown. 相似文献