Method for measuring heat conduction coefficient by using positive and negative bidirectional heat flow method

Abstract

The invention discloses a method for measuring heat conduction coefficients by using a positive and negative bidirectional heat flow method and provides a method for measuring the heat conduction coefficients with high precision by using the positive and negative bidirectional heat flow and constant temperature testing on the basis of American National Standard ASTME1225. According to the testing method, a symmetry testing structure with upper and lower positive and negative bidirectional heat flows is adopted, a high precision temperature sensor is adopted to carry out the bidirectional heat flow testing so as to eliminate error items of each temperature sensor, and the transverse heat flow loss is reduced by combining a controllable temperature heat radiation prevention screen with auxiliary measures, thereby achieving the purpose of measuring heat conduction coefficients of a tested piece with high precision.

Description

technical field [0001] The invention belongs to the field of measuring thermal conductivity, in particular relates to a method for measuring thermal conductivity, and at the same time relates to a device which can be used to accurately measure the thermal conductivity of solid matter. Background technique [0002] The determination of thermal conductivity can be roughly divided into steady-state method and unsteady-state method. The so-called steady-state method is to measure a constant temperature difference of the substance to be measured, and then measure the heat flow formed under the given temperature difference, and the thermal conductivity of the substance can be obtained by Fourier's heat conduction law; the so-called unsteady-state method generally adopts A transient heat source is used for heating, and then the dynamic temperature response of the substance to be determined is measured, and the thermal conductivity of the substance is obtained by analyzing the relat...

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Problems solved by technology

[0003] For the unsteady state measurement method of solid matter, the hot wire method is generally used to measure the thermal conductivity of liquid matter, and the one-dimensional heat conduction inverse problem parameter identification method can usually only obtain analytical solutions under very simple boundary conditions, so it is usually necessary to use The discretized numerical method is used to solve the problem, but for the measurement of one-dimensional temperature difference, it is necessary to ensure the measurement accuracy of temperature, response time and physical properties of materials and other parameters, and it is difficult to guarantee the measurement accuracy of thermal conductivity of materials

In order to form a constant and measurable temperature difference in the steady-state method to determine the thermal conductivity, it needs to be heated for a long time, and there are inevitably different contact thermal resistances between multiple temperature measurement sensors and the test piece, that is, the test piece The temperature of the actual measurement point is necessarily inconsistent with the measured value. Neither the steady-state method nor the unsteady-state method has a good solution to this problem, which affects the measurement accuracy of the thermal conductivity.

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