The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Lidong Chen - One of the best experts on this subject based on the ideXlab platform.
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thermoelectrics direct solar thermal energy conversion
Mrs Bulletin, 2008Co-Authors: Terry M Tritt, H Bottner, Lidong ChenAbstract:Focus The Sun's radiation can be modeled as a 6,000-K Blackbody Radiator. Whereas photovoltaics (PV) can convert the part of the Sun's spectrum to electrical energy, over 40% of that spectrum, namely, the infrared (IR) range, is lost as heat. In solar thermoelectrics (TE), the thermal energy from the IR range is converted directly into electricity. Therefore, a solar PV–TE hybrid system would have access to the entire spectrum of the Sun. Synopsis With respect to solar energy conversion, PV devices utilize the UV region, whereas TE devices utilize the IR region (which is waste heat with respect to the PV devices) to generate electricity. In a solar PV–TE hybrid system, a high-efficiency solar collector would turn the sunlight (from the IR spectrum) into heat that would then be transformed by TE devices into usable electricity. In addition, the solar thermal energy could be stored in a thermal bath, or TE devices could be used to charge batteries that could then provide electricity when the Sun was not shining. Such a TE system would need to operate at around 1,000 K (~700 °C), and the materials would need to exhibit high ZT values around this temperature.
Terry M Tritt - One of the best experts on this subject based on the ideXlab platform.
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thermoelectrics direct solar thermal energy conversion
Mrs Bulletin, 2008Co-Authors: Terry M Tritt, H Bottner, Lidong ChenAbstract:Focus The Sun's radiation can be modeled as a 6,000-K Blackbody Radiator. Whereas photovoltaics (PV) can convert the part of the Sun's spectrum to electrical energy, over 40% of that spectrum, namely, the infrared (IR) range, is lost as heat. In solar thermoelectrics (TE), the thermal energy from the IR range is converted directly into electricity. Therefore, a solar PV–TE hybrid system would have access to the entire spectrum of the Sun. Synopsis With respect to solar energy conversion, PV devices utilize the UV region, whereas TE devices utilize the IR region (which is waste heat with respect to the PV devices) to generate electricity. In a solar PV–TE hybrid system, a high-efficiency solar collector would turn the sunlight (from the IR spectrum) into heat that would then be transformed by TE devices into usable electricity. In addition, the solar thermal energy could be stored in a thermal bath, or TE devices could be used to charge batteries that could then provide electricity when the Sun was not shining. Such a TE system would need to operate at around 1,000 K (~700 °C), and the materials would need to exhibit high ZT values around this temperature.
Alexander H Slocum - One of the best experts on this subject based on the ideXlab platform.
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optical properties of high temperature molten salt mixtures for volumetrically absorbing solar thermal receiver applications
Solar Energy, 2017Co-Authors: Melanie Tetreaultfriend, Luke A Gray, Shapagat Berdibek, Thomas J Mckrell, Alexander H SlocumAbstract:Abstract Molten salts are promising candidates for liquid volumetric absorbers in concentrated solar power systems. To characterize absorption and heat transfer performance in high temperature applications, their optical properties are required. Thus a method for experimentally determining the absorption coefficient of non-scattering high temperature semi-transparent liquids for large (∼1 m-deep) direct absorption solar receiver applications was developed. It was used to measure the absorption coefficient in liquids over a broad spectral range and temperatures up to 800 °C in a 40 wt.% KNO 3 :60 wt.% NaNO 3 binary nitrate molten salt mixture (solar salt) and a 50 wt.% KCl:50 wt.% NaCl binary chloride molten salt mixture. The binary nitrate and binary chloride both demonstrated well distributed solar absorption (>95% absorption through 1 m and 2 m, respectively). At 400 °C, the binary nitrate is optically thick in its re-emission spectrum and behaves as a Blackbody Radiator. The effects of thermal decomposition were also shown to have significant consequences on the overall performance of the binary nitrate mixture, transforming it into an opaque surface absorber following thermal degradation (>95% in
J Hollandt - One of the best experts on this subject based on the ideXlab platform.
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radiation thermometry and emissivity measurements under vacuum at the ptb
International Journal of Thermophysics, 2009Co-Authors: C Monte, B Gutschwager, S P Morozova, J HollandtAbstract: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.
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traceability in fluorometry part i physical standards
Journal of Fluorescence, 2005Co-Authors: J Hollandt, R D Taubert, J Seidel, Ute Reschgenger, A Gugghelminger, Dietmar Pfeifer, Christian Monte, Walter PilzAbstract:The inter-instrument, inter-laboratory, and long-term comparability of fluorescence data requires the correction of the measured emission and excitation spectra for the wavelength- and polarization-dependent spectral irradiance of the excitation channel at the sample position and the spectral responsivity of the emission channel employing procedures that guarantee traceability to the respective primary standards. In this respect the traceability chain of fluorometry is discussed from a radiometrist’s point of view. This involves, in a first step, the realization of the spectral radiance scale, based on the Blackbody Radiator and electron storage ring, and the spectral responsivity scale, based on the cryogenic radiometer and their control via key comparisons of the national metrology institutes. In a second step, the characterization including state-of-the art uncertainties of the respective source and detector transfer standards such as tungsten strip lamps, integrating sphere Radiators, and trap detectors used to disseminate these radiometric quantities to users of spectroscopic techniques is presented.
Peter Reinartz - One of the best experts on this subject based on the ideXlab platform.
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Adaptive Shadow Detection Using a Blackbody Radiator Model
IEEE Transactions on Geoscience and Remote Sensing, 2011Co-Authors: Aliaksei Makarau, Rupert Müller, Rudolf Richter, Peter ReinartzAbstract:The application potential of remotely sensed optical imagery is boosted through the increase in spatial resolution, and new analysis, interpretation, classification, and change detection methods are developed. Together with all the advantages, shadows are more present in such images, particularly in urban areas. This may lead to errors during data processing. The task of automatic shadow detection is still a current research topic. Since image acquisition is influenced by many factors such as sensor type, sun elevation and acquisition time, geographical coordinates of the scene, conditions and contents of the atmosphere, etc., the acquired imagery has highly varying intensity and spectral characteristics. The variance of these characteristics often leads to errors, using standard shadow detection methods. Moreover, for some scenes, these methods are inapplicable. In this paper, we present an alternative robust method for shadow detection. The method is based on the physical properties of a Blackbody Radiator. Instead of static methods, this method adaptively calculates the parameters for a particular scene and allows one to work with many different sensors and images obtained with different illumination conditions. Experimental assessment illustrates significant improvement for shadow detection on typical multispectral sensors in comparison to other shadow detection methods. Examples, as well as quantitative assessment of the results, are presented for Landsat-7 Enhanced Thematic Mapper Plus, IKONOS, WorldView-2, and the German Aerospace Center (DLR) 3K Camera airborne system.