SU415563A1 - - Google Patents

Description

one

The invention relates to the field of determining the thermophysical characteristics (thermal conductivity, temperature, heat capacity) of solid, e.g. building, materials.

Methods are known for determining the thermophysical characteristics of solid materials by creating a heat pulse in a stack of plates of the test and reference materials, measuring the temperature of the heater over time and temperature differences in the plates, and then calculating the coefficients of thermal conductivity, thermal diffusivity and heat capacity from one experiment.

These methods do not provide sufficient accuracy in determining the thermophysical properties in the presence of cryogenic phase transformations in the material under study, because without quantifying the latter, it is not possible to set the optimal heat pulse due to the resolution of measuring devices and the magnitude of heat sources caused by cryogenic phase transitions during the heat pulse .

To improve the accuracy of determining the thermophysical characteristics in the presence of cryogenic phase transformations in the material, a method is proposed by which, before applying a heat pulse, an electrical parameter, such as resistance, of the plates of the material under test is measured, then the ratio of water phases in the material under study is determined the time of the experiment and according to this ratio set the mo1, the capacity of the heat pulse.

The proposed method consists of the following operations.

A package of plates of the investigated n reference materials is placed in a thermostat, in which in the range of positive and negative temperatures: it is necessary to set the required temperature of the air environment. Once the set thermostat temperature has been reset, and this temperature has been evenly distributed throughout the package, which is controlled by differential thermocouple values, the electrical parameter, such as resistance, of the plates of the material under investigation is measured at the given moisture content and temperature. As such a parameter, it is possible to measure the capacity of the test material. The results of measuring the electrical parameter at positive temperatures are used to build a mathematical model that depends on the dependence of the measured electrical parameter on the state of the system (the wet test material), but on the results

measuring the specified parameter at negative temperatures, using the previously obtained mathematical model, determine the amount of unfrozen water and ice in the hole space of the plates of the material under study.

Then, using a flat electric pulse heater, a thermal impulse is created in the package, and the temperature of the heater and the temperature in the plane of contact between the studied and reference nlastins are also fixed in time. On the basis of the obtained experimental data, the coefficients of thermal and thermal diffusivity and ten-intensity of the material are calculated. The magnitude of the heat pulse in the region of negative temperatures is selected according to the conditions mentioned above.

Subject invention

The method for determining the tenlophysical characteristics of building materials by creating a tenl pulse in a stack of plates of the test and reference materials, measuring the temperature of the heater and the lag of temperatures in the plates, and then calculating the thermal conductivity, thermal diffusivity and heat capacity coefficients, in order to improve the accuracy of determination in the presence of cryogenic phase changes in the material, before applying a heat pulse, an electrical parameter is measured, nap Emer resistance, plates of the material, and then can, using the known techniques, determining the ratio of water phase in the material and this sootnoscheniyu

set the power of the tenl pulse.