SU1582101A1 - Method of measuring contact thermal resistance of heterogeneous materials - Google Patents

Abstract

The invention relates to thermal tests, namely to the field of contact thermal resistance measurements. The purpose of the invention is to improve the accuracy and expand the scope. Between the source of heat and identical heat sinks are placed two packages, recruited from the contacting with each other samples of two types. The total thermal resistances of the packages are equal to each other, which is ensured by an equal number of contact planes of dissimilar materials and equal total thermal resistances of samples of each type in the packages. The value of the heat flux between the source and the heat sink is measured, as well as the temperature difference between the points in different packages. These points are separated from the heat source by equal thermal resistances, but different numbers of contact planes. According to the obtained data consider the desired value. Compared to the prototype method, accuracy is improved by eliminating the contribution to the result of calculating the thermal resistance of the sample layer between the temperature measurement point and the contact plane. In addition, the scope is expanded by eliminating the constraint on the ratio of the desired thermal resistance to the thermal resistance of one of the samples. 1 il.

Description

The invention relates to thermal tests, namely to measurements of contact thermal resistances.

The purpose of the invention is to improve the accuracy and expand the scope.

The drawing shows a diagram of the device that implements the method.

The device consists of a source of heat 1, effluent 2, 3 of heat, between which two packages of test samples are placed, each of which consists of three samples 4-6 of the first type and two samples 7, 8 of the second type. In samples 8, a differential thermocouple 9 junction is mounted, which is connected to the secondary device 10 by output. A heat source is connected to the current source 11 circuit together with a wattmeter 12, which measures the power of the heat generated. In this case, signals from the secondary device 10 and the wattmeter 12 are fed to the ratio meter 13, to the output of which indicator 14 is connected, which serves to register the desired value. To reduce heat leaks, the elements of the device are provided with thermal insulation 15. Sample packages are compressed by metered load mechanisms 16, 17.

The number of samples of each type and the total thermal resistances in the two packages located between the source and the heat sinks are equal to each other, and the number of contacts of dissimilar materials in the packages is equal. With source

SP

oo to

heats contact samples of the same type. Due to this, the heat fluxes between the source and the heat sink in two packages are equal to each other. The measurement points of the temperature difference in two packages are arranged in sections separated from the source of heat by equal total thermal resistances of the samples and different numbers of contacting resistances. Due to this, the temperature difference is associated with the desired value and can be calculated with a known value of the heat flux. The formula is:

 dg / f,

where D71 is the temperature difference;

F is the heat flux density. Compared with the prototype method, the proposed method provides improved accuracy by eliminating the effect on the calculation result of the thermal resistance of the sample layer between the temperature gauge and the contact surface. In addition, the field of application of the method is expanded by eliminating the restriction on the ratio of the values of the desired thermal resistance and thermal resistance of one of the types of test samples.

Example. The heat source is made in the form of an electric heater, made of a constantan wire, wound with a step of 1 mm and placed between two layers of a dacron film. The test specimens of the first type are cylinders with a diameter of 15 mm, four of which are 5 thick, and two are 10 mm thick. The samples of the second type studied are cylinders with a diameter of 15 mm, two of which are 10 thick, and two 20 mm thick. In the last two samples, channels 1 mm in diameter and 8 mm deep are drilled at one end of the specimens.

The junctions in them (thermocouples ni; are made in the form of cylindrical chambers with an outer diameter of 15 mm through which water flows at a constant temperature. A chromel-alumel thermocouple with an electrode diameter of 0.2 mm is used as a temperature meter; second type with a height of 20 mm.

The invention can be used in measuring contact thermal resistance between different materials in heat engineering, reactor engineering, aviation and space technology.

Claims (1)

Invention Formula 0 five five The method of measuring the contact thermal resistance of dissimilar materials, which consists in the fact that two packages of different thicknesses of two types are placed in parallel between the source and the drain of heat, the total package. each type of samples and the number of cots in two packages of each type are equal, samples of the same type are brought into contact with the heat source, the heat flow between the heat source and the cooler and the temperature difference between the points in the two packages are measured, on the basis of which about the desired value, characterized in that, in order to increase the accuracy and broaden the scope of application, the samples of the first type perform unequal thickness, measure the temperature difference between points on the axes of different sample packages, and the sum The thickness of the specimens of the first type and the total thickness of the specimens of the second type are the same, and the number of sample contacts between them is different for different sample packs.