Unsteady-state measuring device and method of heat conduction performance of multi-phase porous material

Abstract

The invention relates to an unsteady-state measuring device and a method of heat conduction performance of a multi-phase porous material. The device comprises a sample heating device, a data acquisition system and a computer processing system. The invention is characterized in that the sample heating device consists of four parts, namely a heating circuit, a preheating circuit, a sample and a background material, wherein the sample consists of a measured multi-phase porous material and a laminated material (organic glass), and the organic glass is selected as a first background material and asecond background material for measurement, thus forming the important advantage of the invention that various multi-phase porous materials from low volume density to high volume density can be measured. The testing method can be divided into three major parts, namely preparation of the sample and the background materials, temperature data acquisition and data post processing, and comprises six specific steps. The device can measure heat conduction coefficients, heat diffusion coefficients and volume heat capacity of the multi-phase porous sample, and is especially applicable to the multi-phase porous materials with low volume density. The device is simple and the testing speed is fast and can be finished only by minutes.

Description

technical field [0001] The invention relates to an unsteady-state measuring device and method for the thermal conductivity of multiphase porous materials, which are used for measuring the thermal conductivity, thermal diffusivity and volumetric heat capacity of multiphase porous sample materials. Background technique [0002] In the actual use of various multiphase porous materials, the thermophysical properties of the material determine its thermal insulation and thermal insulation effects. Accurate measurement of thermophysical properties is of great significance for the selection of reasonable multiphase porous materials. [0003] The test method for the thermal conductivity of multiphase porous materials widely used at home and abroad is the steady state method. The principle of the steady-state heat conduction test method is: firstly, a constant temperature difference is formed between the two surfaces of the tested sample. The heat flow through each position in the in...

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Problems solved by technology

[0004] Based on the characteristics of the steady-state heat conduction test principle, there are several factors that will affect the accuracy and credibility of the test results of this method: 1) Since the thermal diffusivity of most multiphase porous materials is very small, in order to make the multiphase porous materials test If a stable temperature difference is formed on both sides of the sample, it will take a long test time to reach the steady-state heat conduction state, and the long-term test will cause the liquid phase inside the multi-phase porous material to evaporate a large amount of water, which will distort the test results; 2) The measured thermal physical property index is single, only the thermal conductivity coefficient of the sample can be measured, and other indicators such as thermal diffusivity cannot be measured, and thermal diffusivity is a very important thermal physical property parameter in the process of unsteady heat conduction; 3) The temperature difference between the two sides of the sample to be tested is 10-20°C. In the heat transfer process of the test, heat conduction, heat convection and heat radiation often act together, so the thermal conductivity of heat conduction cannot be accurately obtained; 4) In order to make the heat flow one-way For one-dimensional flow, the test device must be equipped with a good thermal insulation layer, and the thermal physical properties of the multiphase porous material to be tested are not much different from those of the thermal insulation layer, and the heat leakage at the boundary will affect the test results; 5) In order to maintain the two The temperature difference on the surface is constant, and the test device must have a good constant temperature system, which makes the test device a complex system

[0005] Due to the above shortcomings, for multi-phase porous materials, such as textile materials, it is impossible to use the steady-state method to obtain accurate test results

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