SU1745138A3 - Cooling device manufacturing technique - Google Patents

Abstract

The invention relates to a device for cooling a structure subjected to an intense heat flux, which is continuous, discontinuous or pulsed, by means of fluid-circulation pipes arranged in channels made in the said structure. According to the invention, a flexible material 4 which is a good heat conductor is interposed in the compressed state between the structure 1 to be cooled and each pipe 3. The invention also relates to a method of cooling a structure subjected to an intense heat flux, which is continuous, discontinuous or pulsed, by means of fluid-circulation pipes 3 which are arranged in channels made in the said structure, according to which method each pipe 3 is surrounded beforehand with a layer of flexible material 4, after which each pipe is inserted into the channels 2 and the pipes 3 are expanded under pressure so as to compress the flexible material between the pipe 3 and the channels 2 to a level equal to at least 10 kPa. Application to the cooling of the first wall of a thermonuclear fusion reactor. <IMAGE>

Description

The invention relates to heat engineering and can be used, for example, in the manufacture of chemical, nuclear or thermal reactors, combustion devices, continuous casting of molten metals, targets exposed to x-ray, laser and other radiation.

In the manufacture of cooling devices for structures exposed to intense heat flux of continuous, intermittent or pulsed type, there is a need to

ensuring thermal contact with a high heat transfer coefficient between its elements, which can be made of materials with different thermal expansion coefficients, such as carbon-containing materials, ceramics and metals or alloys.

Elements of dissimilar materials are difficult to assemble with good thermal contact.

From the prior art, a method of manufacturing a graphite heat exchanger is known, consisting of

GJ 00

 WITH

in the graphite block channels, installing metal pipes in them to circulate the working medium and sealing the pipes by pouring graphite powder into the gaps between the pipes and the block.

The disadvantage of this method is that the graphite powder used as a gasket does not provide a high heat transfer coefficient between the walls of pipes and channels. In addition, the reliability of thermal contact between these walls is low due to the likelihood of cavities being formed when the powder is filled.

The purpose of the invention is to increase the heat transfer coefficient and ensure reliable thermal contact.

The goal is achieved by using flexible carbonaceous material as a material for heat-conducting gaskets, gaskets are placed on the outer surface of each pipe before installing it into the channel, and after installing the pipes in the gasket channels, they are compressed with a pressure of at least 10 kPa by expanding the corresponding pipes. At the same time, expanded graphite, carbonaceous or graphite fabrics or felt with filler in the form of metal powder or without it are used as a flexible carbonaceous material.

The choice of expanded graphite gaskets as a material is due to the following circumstance. Expanded graphite is produced by abrupt heating of lamellar graphite to a temperature of 1000 ° C, which leads to the formation of exfoliated graphite, the density of which is about 0.002. This graphite can be re-pressed to a greater or lesser extent into blocks with a density of 0.02-2 or rolled in sheets with a thickness of 0.1–2 mm with a density of up to 1. Graphite treated in this way has a high thermal conductivity in the plane of compression and is relatively low in the perpendicular direction. At the same time it is flexible and elastic. These properties allow expanded graphite to provide good thermal contact between parts of dissimilar materials even with their strong thermal deformations.

Heat transfer coefficients are very sensitive to the state of the surface of elements and difficult to reproduce, which is very inconvenient. Expanded graphite, being placed between the surfaces of the elements, after compression provides reliable thermal contact in any condition of these surfaces, and the introduction of fillers in the form of metal powder into the expanded graphite improves its thermal conductivity.

The advantage of expanded compacted graphite is the anisotropy of its thermal conductivity, which ensures the propagation of a portion of the heat flux in a direction that is perpendicular to the direction of its transfer. Thus, the local thermal maximum on the outer surface of the cooled structure extends to the extended peripheral zone of the cooling pipe, which improves the heat transfer.

Carbon or graphite fabrics and felts, both with and without metal powder filler, also have a fibrous structure due to their fibrous structure.

5 substantially anisotropic thermal conductivity, which makes it possible to use them as gaskets.

The results of the tests showed that the preferred value

0 pressure or compression of expanded graphite gaskets must be at least 10 kPa, which provides a coefficient of heat O

transfer at least 10 W m

TO

-one

The method is implemented as follows.

In the body of the cooled structure, channels are made on the outer surface of each pipe made of a material with a thermal expansion coefficient different from the coefficient of thermal expansion of the material of the body of the structure, a pad of flexible carbonaceous material is placed, then pipes with gaskets are introduced into the channels and subjected to their expansion for example, under the action of hydraulic pressure,

so as to ensure the compression of gaskets at a level of at least 10 kPa.

The proposed method of making a cooling device for a structure exposed to intense

heat flux, provides a high coefficient of heat transfer between structural elements and coolant.

Claims (3)

Invention Formula 1, A method of manufacturing a cooling device for a structure exposed to an intense heat flux of continuous, intermittent or pulse type, by making channels in the body structure, installing last tubes for circulating coolant made of a material with a thermal expansion coefficient different from the coefficient of thermal expansion of the material of the body of the structure, and placing heat-conducting gaskets from the outer surface of the pipes and the inner surface of the channels including carbon, about tl and h ay u and so that, in order to increase the heat transfer coefficient and ensure reliable thermal contact, as e gasket material using a flexible carbonaceous material pads arranged on the outer surface of each tube before placing it into the channel, and after the pipe laying channels in compressed pressure of at least 10 kPa by expanding respective pipes. 2. A method according to claim 1, characterized in that expanded graphite with a metallic filler is used as a flexible carbonaceous material. powder or without it. 3. The method according to claim 1, characterized in that, as a flexible carbonaceous material, carbonaceous or graphite fabrics or felt with filler in the form of metal powder or without it.