Method for determining the thermal conductivity of insulation bricks

In the field of construction, insulation bricks have become an important material for building envelope structures due to their excellent thermal insulation performance. The thermal conductivity, as a core parameter for measuring the performance of insulation bricks, directly affects the energy consumption and indoor thermal environment quality of buildings. But how to accurately measure the thermal conductivity of insulation bricks is of great significance for building energy-saving design, insulation material research and development, and quality control.

　　1、 Definition of thermal conductivity of insulation bricks

　　1.1 What is thermal conductivity?　

Thermal conductivity refers to the energy transferred through an area of 1m under stable heat transfer conditions, with a temperature difference of 1k between the two sides of a 1m thick material, in W/(m * k) within 1 second. It reflects the ability of the material to conduct energy, and the smaller the thermal conductivity, the better the insulation performance of the material.

　　1.2 Factors affecting the thermal conductivity of insulation bricks

1.1.1 Composition and structural composition of materials. The type, proportion, and internal pore structure of insulation bricks have a significant impact on their thermal conductivity.

1.1.2 Temperature. In general, with the increase of temperature, the molecular thermal motion inside the insulation brick is intense, and the thermal conductivity will significantly increase.

1.1.3 Humidity. The invasion of moisture will fill the gaps inside the insulation brick, and the thermal conductivity of water is much higher than that of air, causing an increase in the thermal conductivity of the thermal insulation brick.

　2、 Experimental steps　

　　2.1 Preparation before Inspection　

Sample preparation: We select a piece of insulation brick with a smooth and flat surface, and a specification of not less than 100mm * 100mm * 10mm for testing.

　　2.2 Measurement Methods　

This experiment used the transient heat source method, which determines the thermal conductivity by measuring the temperature change of the material during instantaneous heating or cooling.

　 2.3 Experimental Equipment

DZDR-S Thermal Conductivity Tester (produced by Nanjing Dazhan Instrument).

　　2.4 Experimental steps　

2.4.1 Equipment calibration: Before the experiment begins, the thermal conductivity meter needs to be calibrated to ensure the accuracy of the test results. The calibration steps include coefficient calibration to ensure that the instrument can stably and accurately record data during the testing process.

2.4.2 Place the sample between the upper and lower fixtures (as shown in the figure below) and adjust the required parameters according to the operating instructions, such as time (160), probe, power, and reference.

2.4.3 Conduct software data collection, fill in power and probe resistance for thermal conductivity calculation, and obtain accurate data results. Then perform two parallel verifications of the repeatability of the results, as shown in the following figure.

Di test result: 0.132934

Second test result: 0.139070

The repeatability of the two test results is good, and the results are relatively parallel. This test has a reliable experimental basis for the thermal conductivity of the insulation brick.

　2.5 Experimental analysis

The indoor temperature fluctuates, and as the temperature increases, the thermal conductivity will significantly increase. The difference in pore size, normally speaking, insulation bricks with high porosity and small pore size will have lower thermal conductivity when tested. When the humidity increases, the thermal conductivity of the insulation brick will also significantly increase.

　2.6 Experimental Conclusion

The thermal conductivity of insulation bricks is a key indicator for measuring their insulation performance, and the lower the thermal conductivity, the better the insulation performance. Accurately measuring the thermal conductivity of insulation bricks through a thermal conductivity tester can provide a visual understanding of their insulation performance, thereby determining whether the insulation brick meets relevant quality standards and requirements, and providing important basis for engineering material selection.