In Situ Measurements of Spectral Emissivity of Materials for Very High Temperature Reactors

Cao, Guoping; Weber, S. J.; Martin, S.O.; Malaney, Tamara L.; Slattery, Stuart R.; Anderson, Mark; Sridharan, Kumar; Allen, Todd R.

doi:10.13182/nt11-a12317

Cited by 24 publications

(7 citation statements)

References 4 publications

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“…Measurement systems have also been developed using a solar simulator as the heater for measuring the emittance of a cobalt chromium-nickel alloy and pure niobium at high temperatures for the Solar Orbiter mission [52] or the emittance of lunar soils [56]. In another study, Cao et al [57] constructed an instrument for gas-cooled, high-temperature reactor materials using a rotating sample holder with seven sample holes and one blackbody hole to achieve fast switching between the reference and sample measurements. Gorewoda and Scherer [58,59] devised a measurement setup to study the emittance of carbonates and sulfates in coal ashes from oxyfuel combustion.…”

Section: Direct Measurementsmentioning

confidence: 99%

Spectral emittance measurements of micro/nanostructures in energy conversion: a review

et al. 2020

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Micro/nanostructures play a key role in tuning the radiative properties of materials and have been applied to high-temperature energy conversion systems for improved performance. Among the various radiative properties, spectral emittance is of integral importance for the design and analysis of materials that function as radiative absorbers or emitters. This paper presents an overview of the spectral emittance measurement techniques using both the direct and indirect methods. Besides, several micro/nanostructures are also introduced, and a special emphasis is placed on the emissometers developed for characterizing engineered micro/nanostructures in high-temperature applications (e.g., solar energy conversion and thermophotovoltaic devices). In addition, both experimental facilities and measured results for different materials are summarized. Furthermore, future prospects in developing instrumentation and micro/nanostructured surfaces for practical applications are also outlined. This paper provides a comprehensive source of information for the application of micro/nanostructures in high-temperature energy conversion engineering.

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Section: Direct Measurementsmentioning

confidence: 99%

Spectral emittance measurements of micro/nanostructures in energy conversion: a review

et al. 2020

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“…In the step two characteristic of standard calibration procedures, complex emissivity tests [8][9][10][11][12][13][14][15][16] have to be conducted in order to calculate the correction factor for (Eq. 7) needed to obtain the real surface temperature ( in Eq.…”

Section: A) Basmentioning

confidence: 99%

Design of the Experimental Campaign on Variable Transpiration Cooling for Reusable Thermal Protection Systems

Gulli¹,

Maddalena²,

Moghadam

et al. 2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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Reusable thermal protection systems are one of the key technologies that have to be improved in order to enable long-duration hypersonic flights and a more affordable access-to-space by means of single-stage-toorbit vehicles. The transpiration cooling has been demonstrated to be one of the most promising cooling techniques in terms of coolant mass saving and minimum disturbances of the external flow. The coupling of the boundary layer with the thermal response of selected porous materials plays a crucial role in enabling the practical use of the transpiration cooling technique for reusable thermal protection systems. Numerical studies conducted by the authors, on the aforementioned coupling, have introduced the new concept of the variable transpiration cooling which allowed identifying a particular cooling strategy (i.e. saw-tooth wall velocity distribution) able to reduce the total amount of coolant used by 37% with respect to other cooling strategies explored. The current capability of manipulating the natural properties of porous materials (e.g. porosity, permeability and thermal conductivity) renewed the interest on demonstrating experimentally the cooling potential of the transpiration strategies simulated numerically. The design phase of the experimental campaign on variable transpiration cooling for testing a full-scale thermal protection system in the 1.6 MW arc-heated wind tunnel located at the University of Texas at Arlington is presented in this work. The prototype thermal shield to be used for the experiments is an axisymmetric carbon-carbon cone having tailored porosity and variable thickness prescribed at the manufacturing level in order to reproduce a variable blowing profile. An innovative calibration procedure of the infrared camera used to map the temperature of the external surface, which is based on simultaneous measurements of the local temperature and intensity of radiation, is described in detail. The results obtained in this work highlight the potential of using the calibration methodology proposed for retrieving the surface temperatures without using blackbody radiators/cavities and without relying on elaborated tests for emissivity characterization which are both needed in standard calibration procedures for infrared camera systems. A preliminary analysis of the optical properties of the plasma flow is also provided in order to assess the impact of the plasma's emissivity on the surface temperature map that will be obtained during the final experiment on transpiration cooling.

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“…18 Generally, ceramic coatings, which are known to possess high-emissivity values, are widely coated on metallic radiators to enhance radiative heat dissipation. 19−24 For instance, a nanoporous anodic oxidation Al 2 O 3 layer was employed to improve the radiative heat dissipation of aluminum alloy by enhancing the emissivity value in wavelengths of 5−20 μm, 4 30 Although some literature indicates SiC could enhance the emissivity values apparently, the difficult preparation of SiC coating limited by the high-temperature process, tedious procedure, and high cost hinders large-scale industrial productions and applications. Besides, the radiative heat dissipation performance of SiC coating related to high infrared emissivity value has been rarely investigated.…”

Section: Introductionmentioning

confidence: 99%

Facile One-Step Fabrication of Multilayer Nanocomposite Coating for Radiative Heat Dissipation

Zou

Wang

Wei

et al. 2019

ACS Appl. Electron. Mater.

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To enhance the radiative heat dissipation in thermal management of electronic and optical devices, a novel structural nanocomposite coating was fabricated via facile onestep liquid-phase plasma assisted electrophoresis and sintering (LPES) technique. The results indicate that the larger amount of SiC addition in the electrolyte results in more nanoparticles being incorporated into the coating. When the concentration increased to 8 g/L, the saltation of that formation of a multilayer structure occurred for the nanocomposite coating. According to transmission electron microscopy, scanning electron microscopy, glow discharge optical emission spectroscopy, and energy dispersive spectroscopy results, a speculated mechanism model was proposed to reveal the LPES process. Furthermore, the nanocomposite coating improved the emissivity value, especially in the range of 3−8 μm, where the value was up to 0.86. Compared with the bare aluminum substrate, the coating formed with 8 g/L SiC addition enables the temperature drop by 10.0 and 15.8 °C for 1 and 5 W power LED, which yields the highest cooling efficiency of 19.1% and 21.0%, respectively. The simple and scalable nanocomposite coating fabrication approach by one-step LPES method exhibits excellent passive heat dissipation performance, which has potential applications in large power radiators of the electronic industry.

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In Situ Measurements of Spectral Emissivity of Materials for Very High Temperature Reactors

Cited by 24 publications

References 4 publications

Spectral emittance measurements of micro/nanostructures in energy conversion: a review

Spectral emittance measurements of micro/nanostructures in energy conversion: a review

Design of the Experimental Campaign on Variable Transpiration Cooling for Reusable Thermal Protection Systems

Facile One-Step Fabrication of Multilayer Nanocomposite Coating for Radiative Heat Dissipation

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