Apparent directional spectral emissivity determination of semitransparent materials

Niu, Chun-Yang; Qi, Hong; Ren, Yukun; Ruan, Li-Ming

doi:10.1088/1674-1056/25/4/047801

Cited by 15 publications

(3 citation statements)

References 35 publications

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“…The above-listed qualities of sapphire allow it to retain all the optical properties and make it an indispensable material for working at high temperatures. Considering the spectral range of the IR camera lens and the steady transmittance of sapphire at wavelengths in the range of 3–5 μm, the level of transmission is 85%. , …”

Section: Methodsmentioning

confidence: 99%

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Temperature Profile Mapping over a Catalytic Unit of a Hydrogen Passive Autocatalytic Recombiner: An Experimental and Computational Fluid Dynamics Study

et al. 2020

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Passive autocatalytic recombiners (PARs) are used for the removal of accidentally released hydrogen inside confined spaces. The high catalyst surface temperature is an important safety issue to be considered in the use of a PAR. The ability to predict the catalyst surface temperature could be very useful in preventing the self-ignition and explosion of hydrogen inside the PAR. This study seeks to investigate the changes in temperature profiles of the PAR catalytic section upon variation of the inlet hydrogen concentration. Experiments were conducted on a small-scale test setup. The catalytic section comprised cylindrical ceramic elements arranged in parallel and held upright by a stainless-steel frame. The temperature profiles were measured with a high-resolution infrared camera. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used as a numerical tool for modeling the gas mixture flow inside the experimental setup and the chemical reaction kinetics. The results of numerical studies are presented and compared with experimental results. The presented CFD-based approach and software offer an appropriate numerical tool for the investigation of hydrogen safety issues. Finally, the catalyst was subjected to a prolonged high-temperature combustion fatigue procedure to determine its stability. The surface of the fatigued catalyst was evaluated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was found that decomposition of the protective surface layer occurred at elevated temperatures; the catalytic activity was unaffected by this. In addition, a relatively uniform reactive metal particle size was maintained over the entire temperature range, suggesting that no aggregation occurred.

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Section: Methodsmentioning

confidence: 99%

“…Considering the spectral range of the IR camera lens and the steady transmittance of sapphire at wavelengths in the range of 3−5 μm, the level of transmission is 85%. 31,32 2.3. Set of Input Parameters.…”

Section: Methodsmentioning

confidence: 99%

Temperature Profile Mapping over a Catalytic Unit of a Hydrogen Passive Autocatalytic Recombiner: An Experimental and Computational Fluid Dynamics Study

et al. 2020

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“…[11][12][13][14][15] Thus, various optimization methods with anti-ill-posedness are developed. Heuristic algorithms [7,[16][17][18][19] and gradient algorithms, [20][21][22] as the typical inverse methods, are widely used to solve the inverse problems. For the IHTPs, Vakili and Gadala [23] used particle swarm optimization (PSO) algorithm to estimate the boundary conditions with different dimensions.…”

Section: Introductionmentioning

confidence: 99%

Model predictive inverse method for recovering boundary conditions of two-dimensional ablation*

Wang¹,

Zhang²,

Chen³

2021

Chinese Phys. B

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A model predictive inverse method (MPIM) is presented to estimate the time- and space-dependent heat flux on the ablated boundary and the ablation velocity of the two-dimensional ablation system. For the method, first of all, the relationship between the heat flux and the temperatures of the measurement points inside the ablation material is established by the predictive model based on an influence relationship matrix. Meanwhile, the estimation task is formulated as an inverse heat transfer problem (IHTP) with consideration of ablation, which is described by an objective function of the temperatures at the measurement point. Then, the rolling optimization is used to solve the IHTP to online estimate the unknown heat flux on the ablated boundary. Furthermore, the movement law of the ablated boundary is reconstructed according to the estimation of the boundary heat flux. The effects of the temperature measurement errors, the number of future time steps, and the arrangement of the measurement points on the estimation results are analyzed in numerical experiments. On the basis of the numerical results, the effectiveness of the presented method is clarified.

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Radiation heat transfer during hypersonic flight: A review of emissivity measurement and enhancement approaches of ultra‐high temperature ceramics

Saad

Martínez

Trice

2023

Int J Ceramic Engine & Sci

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Emissivity as a function of wavelength, direction, and temperature correlates to a material's efficiency in radiating thermal energy. Knowledge of emissivity is essential for designing and developing radiation-cooled thermal protective systems for hypersonic applications. It is desirable to achieve a high emissivity (with a value close to 1) to maximize heat radiation from a hot surface of a hypersonic vehicle's leading edge during atmospheric re-entry. With the goal of providing the hypersonic materials community with this necessary knowledge, this article offers a basic understanding of thermal radiation, methods for measuring emissivity at high temperatures, and a comprehensive overview of the emissivity of ultra-high temperature ceramics.

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Apparent directional spectral emissivity determination of semitransparent materials

Cited by 15 publications

References 35 publications

Temperature Profile Mapping over a Catalytic Unit of a Hydrogen Passive Autocatalytic Recombiner: An Experimental and Computational Fluid Dynamics Study

Temperature Profile Mapping over a Catalytic Unit of a Hydrogen Passive Autocatalytic Recombiner: An Experimental and Computational Fluid Dynamics Study

Model predictive inverse method for recovering boundary conditions of two-dimensional ablation*

Radiation heat transfer during hypersonic flight: A review of emissivity measurement and enhancement approaches of ultra‐high temperature ceramics

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