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Heat Transfer Research
Fator do impacto: 0.404 FI de cinco anos: 0.8 SJR: 0.264 SNIP: 0.504 CiteScore™: 0.88

ISSN Imprimir: 1064-2285
ISSN On-line: 2162-6561

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Heat Transfer Research

DOI: 10.1615/HeatTransRes.2019027800
Forthcoming Article

MODELING EFFECT OF THE SURFACE OXIDIZATION ON THE NORMAL EMISSIVITY OF RED COPPER T1 at A WAVELENGTH OF 1.5 ?m AND TEMPERATURE RANGE FROM 800 TO 1100 K

Deheng Shi
Henan Normal University
Shan Sun
Henan Normal University
Zunlue Zhu
Henan Normal University
Jinfeng Sun
Henan Normal University

RESUMO

This work endeavors to study the effect of surface oxidization on the normal spectral emissivity of red copper T1 samples at 1.5 μm. The normal emissivity is measured over a temperature range from 800 to 1100 K during a 6-h heating period. The radiance emitted by the specimens is received by an InGaAs photodiode detector, which works at 1.5 μm with a bandwidth of approximately 20 nm. The temperature of sample surface is obtained by averaging the readings of two thermocouples, which are symmetrically welded in the front surface of specimens near the measuring area. The strong oscillation of emissivity appears only during the initial heating period at each temperature, which is affirmed to be connected with the thickness of oxide layer. The interference effect is discussed between the radiation stemming from the oxide layer and the radiation from the underlying metal substrate, which is responsible to the strong oscillation. The uncertainty of emissivity yielded only by the surface oxidization is approximately 2.9% to 14.3%. The temperature uncertainty generated only from the surface oxidization is approximately 2.5 to 8.8 K. The models of normal emissivity with heating time are evaluated at a certain temperature. A simple functional form is found to reproduce well the variation of normal emissivity with heating time, including the reproduction of strong emissivity oscillation occurring during the initial heating period.