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Nondestructive steady-state thermal conductivity measurement method

A measurement method and technology of thermal conductivity, which is applied in the field of non-destructive steady-state thermal conductivity measurement, can solve the problems of limited engineering field application, complex measurement device, and long time, and achieve the effects of shortened measurement time, wide measurement range, and low preparation requirements

Active Publication Date: 2018-11-30
SHANGHAI UNIV OF ENG SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The advantage of the steady-state measurement method is that the mathematical model is simple, but it takes a long time for the sample to reach a thermal steady state during the measurement, so the entire measurement process takes a long time (about tens of minutes)
At the same time, the measurement device corresponding to the steady-state thermal conductivity measurement method is complicated, and the sample needs to be processed into a specified shape, which limits its engineering field application

Method used

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Embodiment 1

[0061] In this embodiment, the temperature field on the surface of the sample is characterized by measuring the temperature difference between any two points on the heated surface of the sample. Select two measured points with different spatial positions near the heating point, and measure the temperature difference between them, and obtain the temperature rise of the two measured points as:

[0062] T 1 –T 0 =Q·F 1 / κ

[0063] T 2 –T 0 =Q·F 2 / κ

[0064] The temperature T of these two points 1 , T 2 It is obtained at the same time, not the temperature difference between a certain point before and after heating; and the spatial position of the two points is very close to the heating point, and the influence of the environment (convection effect, etc.) on the heating point and the measurement point can be ignored, effectively avoiding the environment during outdoor measurement influences. Sample thermal conductivity κ and temperature difference ΔT between two points ...

Embodiment 2

[0069] The method can be used to non-destructively detect the composition and distribution of heterogeneous materials. In this embodiment, the method and device are used to scan the variation of the thermal conductivity of the cement brick surface with the spatial position, such as Figure 4 As shown, it can be used to assist in characterizing the distribution of different components in cement bricks.

Embodiment 3

[0071] The method can be used to detect cracks in materials non-destructively. In this embodiment, there are cracks on the surface or shallow surface of the cement brick, and the cracks can be considered as filled with air, without heat absorption, so there is no obvious temperature rise, and the equivalent thermal conductivity of the cracks changes abruptly, as shown in Figure 5 As shown, the peak position in the figure represents the crack, and this method can be applied to the non-destructive detection of voids and cracks on the front surface of engineering materials.

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Abstract

The invention relates to a nondestructive steady-state thermal conductivity measurement method. The method comprises the following steps: 1) for a bulk material, the surface of a sample is heated by apoint heating method by means of a heating source, and for a film material, the sample and a comparative material with a known thermal conductivity are heated by a zone heating method; 2) when the sample reaches a thermal steady state, for the bulk material, the temperature field of the sample surface is characterized by measuring the temperature change at any point on the heating surface of thesample or the temperature difference between any two points, for the film material, the temperature change at any point in the heating zone of the sample and the comparative material can be measured for characterization; and 3) the thermal conductivity of the sample is obtained by a physical model of the thermal conductivity of the sample and the temperature field of the sample surface. Compared with the prior art, the method has the following advantages: 1) same side heating and detection of the sample can be realized, the method can be applied to non-destructive measurement; 2) sample preparation and measurement equipment can be simplified, and measurement time can be shortened; and 3) the environment influence is small, and the method can be used for measuring the heat conductivity under a plurality of environment.

Description

technical field [0001] The invention relates to a material thermal conductivity measurement technology, in particular to a nondestructive steady-state thermal conductivity measurement method. Background technique [0002] Thermal conductivity is an important thermophysical property parameter of materials, and rapid and simple thermal conductivity measurement technology has become very important at present. In the existing thermal conductivity measurement technology, according to the physical model of the measurement method, it can be roughly divided into a steady-state thermal conductivity measurement method and a transient thermal conductivity measurement method. Common steady-state thermal conductivity measurement methods include hot wire method (Searle’s barmethod) and hot disc method (Lee’s disc method). The hot wire and hot plate methods are suitable for the measurement of thermal conductivity of materials with high thermal conductivity and materials with low thermal c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N25/18G01N25/20
CPCG01N25/18G01N25/20
Inventor 徐屾张恒运王信伟高楷然
Owner SHANGHAI UNIV OF ENG SCI
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