System and method for testing low-temperature hemispherical emissivity of material

Abstract

The invention relates to the technical field of material emissivity measurement, in particular to a system and a method for testing low-temperature hemispherical emissivity of a material. The system for testing the low-temperature hemispherical emissivity of the material comprises a testing device, a vacuum pump, a refrigerating device and a temperature control device, the vacuum pump and the refrigerating device are connected with the testing device, and the testing device comprises a vacuum cover, a shielding cover, a radiation screen cover and a sample table hung in the radiation screen cover. The sample table comprises an electric heating sheet and two metal sheets which are respectively arranged on two sides of the electric heating sheet, a tested sample coating is respectively arranged on one side, opposite to the electric heating sheet, of each metal sheet, a thermometer is respectively arranged on each metal sheet, and the electric heating sheet and each thermometer are respectively connected with the temperature control device. The system for testing the low-temperature hemispherical emissivity of the material provided by the invention can realize continuous measurement of the average hemispherical emissivity of the material from 10K to 300K, and the measurable temperature range is larger, so that the measurement accuracy is improved.

Description

technical field [0001] The invention relates to the technical field of material emissivity measurement, in particular to a test system and method for low-temperature hemispherical emissivity of materials. Background technique [0002] Radiation heat transfer is the main heat transfer mode in low temperature environment, and thermal emissivity is an important parameter to characterize the thermal radiation characteristics of materials. Thermal emissivity at low temperatures is often required to calculate radiant energy and infrared background radiation. The radiation of an actual object is different from that of a black body. As long as the surface temperature of the object is higher than 0K, it will emit radiation energy of different wavelengths in different directions in the hemispherical space above the surface, and will also absorb radiation energy from all directions. The emissivity of a material is defined as the ratio of the total energy emitted by an actual object to...

AI Technical Summary

Problems solved by technology

However, it is a great challenge to accurately measure the low-temperature thermal emissivity of metals and coatings, because the wavelength of thermal radiation at low temperature is mainly above 20 μm, and the background radiation will bring great uncertainty

[0004] At present, in the existing technology, the measurable temperature range of emissivity is narrow, and it is impossible to measure the average hemispherical emissivity when the sample temperature drops to 10K, and the measurement is heavily dependent on the cooling of cryogenic liquids such as liquid helium and liquid nitrogen, resulting in Waste of cryogenic liquid, cumbersome test process

In addition, the sample size is fixed and the area is relatively large in the existing measurement device, which is not conducive to the average hemispherical emissivity measurement of scarce and expensive sample materials

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