Laser flash method-based thermal diffusion coefficient test device and method

Abstract

The invention provides a laser flash-based thermal diffusion coefficient test device and method. The laser flash-based thermal diffusion coefficient test device comprises a laser conductometer, a base which is fixed on the laser conductometer, a sample vessel which is arranged at the top of the base and a cover covering the sample vessel, wherein a cut-through degassing hole is formed in the side wall of the sample vessel; the cover consists a first section, a second section and a third section, the diameters of which are gradually decreased; the bottom surface of the first section leans against the top surface of the sample vessel; an overflow space is formed between the outer surface of the third section and the inner surface of the sample vessel; the overflow space is communicated with the external environment through the degassing hole. According to the laser flash-based thermal diffusion coefficient test device, the overflow space formed between the outer surface of the third section and the inner surface of the sample vessel leaves a warming inflation space for samples, so that the samples are prevented from overflowing out of the sample vessel to influence the test result. In the test process, the gas in the samples is discharged from the overflow space to the external environment through the degassing hole, so that isotropic and uniform samples can be prepared.

Description

technical field [0001] The present invention relates to the test of thermal diffusivity, more specifically to a thermal diffusivity test device and method based on laser flash method. Background technique [0002] Thermal diffusivity is the ratio of the thermal conductivity of a substance to its specific heat capacity and density, which characterizes the ability of heat transfer in an object and is an important physical parameter of unsteady heat conduction. Specific heat capacity and density are the properties of the substance itself, and the test method is very mature. Therefore, as long as the thermal diffusivity of the substance is tested, the thermal conductivity can be determined. Thermal diffusivity / thermal conductivity is of great significance in chemical engineering, engineering thermophysics, mechanical engineering, cryogenic engineering, metrology, materials science and other disciplines. Studying the thermal diffusivity / thermal conductivity of fluids is not only...

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Problems solved by technology

For example, although the hot wire method mentioned above is simple and convenient, the error caused by the severe shunt phenomenon caused by the conductivity of the molten salt increases with the temperature is 20%; the hot plate method can reduce the ionization degree of the molten salt, However, there are few available container materials and the design is complicated; the radiative heat loss of the periodic heat flow method is small, but the evaluation of hydraulics and the length of the thermal inlet brings errors, and the error is 20%.

In the 1960s, the Oak Ridge National Laboratory of the United States proposed a variable gap method aimed at measuring the thermal conductivity of molten salt, but actual thermal calculations show that the error of this method is larger, and the experimental error can reach 400%.

[0005] However, for the laser flash method, the inhomogeneity of the sample itself will cause large errors

Since the density of molten salt decreases with the increase of temperature, it is impossible to obtain isotropic molten salt by directly setting the molten salt in the existing sample dish and using the existing laser flash method for testing, and it is also impossible to obtain accurate test results

Therefore, the test method of molten salt thermal diffusivity based on the laser flash method has not been reported yet.

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