SU402759A1 - DEVICE FOR TEMPERATURE MEASUREMENT - Google Patents

Description

The invention can be used to measure the surface temperature of various bodies, including parts and assemblies of nuclear power facilities.

Devices for measuring temperature, e.g., nuclear reactor piping, linking channels to group collectors, comprising an overlay housing on the pipe and a thermometer are known.

However, in a number of cases, the use of these devices does not give the desired effect due to various physical, technological and operational reasons (the presence of so-called "critical insulation thickness, limitation of dimensions, requirements for ease of maintenance, etc.).

In order to improve the measurement accuracy in the proposed device, a heat shield made of heat-conducting material, covering the case and the item being inspected, is fixed on the overlay body through the thermal insulation layer.

FIG. 1 shows a variant of the proposed device; in fig. 2 - its thermophysical scheme.

The device is a laid-on housing 1 placed on the pipe 2 and covered with a layer of thermal insulation 3. A thermometer 4 is installed in the opening of the housing 1. A screen 5 of highly heat-conducting material, such as aluminum, fastened with screws 6 is located above the pipe 2 and insulation 3.

Since the laid-on body 1 is made of highly heat-conducting material, to simplify the analysis of the heat transfer process, the temperatures throughout the cross-section of the body 1 can be assumed to be the same.

The specific heat flux from the surface of housing I to the environment with temperature is determined by the formula (in the absence of a screen):

(one),

where K is the heat transfer coefficient lf- +

Chi,

a - heat transfer coefficient

from broke: Noah surface

isolation to the surrounding

Wednesday,

A is the insulation thickness, and Кn is the thermal conductivity coefficient of the insulation material.

Formula (1) allows analytically to investigate ways to reduce heat leaks from the surface shell, which determine the dimension of the temperature measurement of HopiHocTb.

Since the coefficient a in typical cases (as insulation material is considered asbofluoroplast) is approximately an order of magnitude less than the AI / ZI value, reducing the leakage of tenl only by increasing the thickness of the insulation layer is ineffective. Decrease another parameter, tempera M i, -to

This may be due only to an increase in temperature f.

Since it does not make sense to consider the issue of raising the temperature of the whole room, it seems most appropriate to create a microclimate in the zone near the insulation, so that the temperature in this zone is higher than the ambient temperature and as close as possible to the temperature of the part being monitored. To do this, it is enough to close the insulation 3 with a continuous heat shield 5 connected (in the thermal sense) to the hot surface.

for example, pipes 2, whose temperature is measured.

It is obvious that the use of high heat-conducting materials (for example, aluminum) increases the average temperature of the screen and increases the efficiency of the design.

Screen 5 can also be used as an element for insulating ankle and a surface housing on the part being inspected.

Subject invention

A device for measuring temperature, for example, pipelines of a nuclear reactor, comprising an overlay housing, a housing attachment unit and a thermometer, characterized in that, in order to improve the measurement accuracy, a heat shield made of ten-conductive material, enclosing the housing and monitored, is attached to the patch root. detail.

Aa

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