DE1950448A1 - Switchable heat pipe - Google Patents

Abstract

The heat pipe features heat absorbing and heat dissipating surfaces with vapour condensation at the cooled end. The condensate is returned by the capillaries in the pipe liner, and the externally switched diaphragm is in contact with an heat insulating layer of the pipe.

Description

BROWN, BOVERI & CIE · AKTIENGESELLSCHAFT

MANNHEIM BROWN BOVERI

Mp.no. 658/69 Mannheim, September 25, 1969

Pat / P / Bu.

"Switchable heat pipe"

The invention relates to a switchable heat pipe with a first section which absorbs heat from the outside and in which the working fluid evaporates ("hot point") and one to the outside heat-emitting second section in which the steam condenses ("cold spot"), the two sections for the Working fluid combined to form a closed circuit and for the return of the condensate conductive medium in the form of Capillaries are provided.

Hit heat pipes can generate large amounts of heat per unit area be transported. The heat pipes are independent of position and usable in a wide temperature range if you have the; Selects the working medium accordingly. Heat pipes are special has been proposed which, depending on needs, a very large one or to be able to transfer a very small amount of heat, the object being achieved in different ways.

A first possible solution is to use it a working fluid with a large change in vapor pressure. This ensures that the thermal conductivity changes greatly as a function of the temperature (P 19 37 728.3). '' The transition from high to low thermal conductivity or vice versa is therefore associated with a change in temperature, v / au is disadvantageous in some cases.

In addition, the temperature is used as a parameter eliminated by ordering control means that the

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Condensate in the second section, i.e. at the cooled point, held back and thus the cycle of the working fluid • interrupt or release again.

According to the second proposal, the condensed working medium is retained in a cold finger when the system is switched off. _R by a D ehung the heat pipe working fluid flows into the actual heat pipe, whereby the heat transfer wfeder used. However, the rotation required for the switching process makes the installation of the heat pipe more difficult (P 19 43 122.2).

According to the third proposal, there is a displacement body in the heat pipe, which is raised from the outside or into the Condensate can be lowered. In the latter case, the condensate comes in with the capillary structure of the heat pipe jacket Contact, in the first place. Therefore, in the latter case, working fluid and therefore heat are transported, in the first case Do not fall. The displacement body, however, creates additional heat transfer problems between it and the working fluid below and above it. The storage of the condensate until the final Interruption of the heat transport takes some time (P 19 43 122.2). An immediate shutdown of the heat pipe can be achieved Achieve interruption of the condensate return as described in To a certain extent by lifting the displacement body described from the stored condensate happens. In the Condensate return can intervene if the capillary structure is interrupted at one point, which, however technically difficult to accomplish.

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The invention aims, however, an immediate shutdown and the possibility of rapid commissioning of the heat pipe without the need for extensive mechanical aids and largely independent of the temperature.

The solution is based on a heat pipe of the type described at the beginning Genus and consists according to the invention that A screen is built into the heat pipe through which the heat transport due to the interruption of the steam flow can be reduced and switched off. The screen can be built into the heat pipe as a whole and can be externally e.g. operated electromagnetically. The main advantage of the invention lies in the immediate shutdown of the heat transport, because the jacket of the heat pipe does not transfer any heat if it is at least partially made of heat-insulating material Material.

If the steam flow is interrupted by means of the diaphragm, so Theoretically, the sections in front of and behind the panel can act individually as a heat pipe. According to the invention, however Means are provided that avoid or reduce this undesirable effect. The aperture consists of, one heavy wettable material and is extremely smooth (see, "Chemical Engineer Technology", Volume 39, 1967, issue 1, pp. 13-20, especially p. 13 and the same magazine, volume 35, 1963, issue 11, p. 775-784, especially p. 775). The diaphragm is homogeneously hydrophobic, e.g. when using V / ater as the working fluid. she is also arranged in such a way that it practically does not absorb any condensate that may still flow back. The shape of the aperture can can be very different, e.g. it can be arranged to be rotatable or composed of sliding individual pieces (bellows) be. In the immediate vicinity of the panel, the wall of the heat pipe can be made of heat-insulating material.

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hen so that no heat is conducted through the wall into the heat-emitting part of the heat pipe (after the diaphragm).

Heat can be transported between the diaphragm and the heat-emitting section because of the advantageous measures provided switch off or largely reduce it and control it to a small extent by means of the aperture setting.

In the drawings, an embodiment of the invention is shown, which is described below. Bs show:

1 shows a cut-open heat pipe with an electromagnetically switchable diaphragm for the vapor barrier;

FIG. 2 shows an exemplary capillary structure according to FIG section line indicated in FIG. 1;

A heat pipe 1 with a heat-absorbing side 2 and a heat-emitting side 3, on which a heat sink (not shown) is arranged, has a on its inner wall Capillary structure 4. Schematically is an elei ·; i; ro table rotatable panel shown. In the immediate vicinity the cover 5, the jacket of the heat pipe 1 consists of a heat-insulating in relation to the usual wall material Material 6.

The mode of operation of the exemplary embodiment is based on the above Description.

In addition to the interruption of the steam flow, of course, in an extended embodiment of the invention, the The switching options described at the beginning must be used:

Condensate storage and sudden change in steam pressure as a function on the temperature.

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Claims (4)

- 5 -. 658/69 Claims (1. jSchalfbaren heat pipe with a heat absorbing from the outside ^ - ^ the first section, in which working fluid ver » steams ("hot" point) and a second section that emits heat to the outside, in which the steam condenses ("cold" Place), with the two sections for the working fluid combined into a closed circuit and conducting means in the form of capillaries are provided for the return of the condensate, characterized in that that in the heat pipe (1) an aperture (5) is installed through which due to the interruption of the steam flow the heat transport can be reduced or switched off. 2. Switchable heat pipe according to claim 1, characterized in that the diaphragm (5) from the outside electromagnetically is operated. 3. Switchable heat pipe according to claim 1 and claim 2, characterized in that the diaphragm (5) has a Bellows is operated mechanically. 4. Schaltbareu heat pipe according to claim 1 and claim 2, characterized in that the wall of the heat pipe zürn.indent in the immediate vicinity of the cover made of heat-insulating Material (6) consists. b. So durable3 heat pipe according to claim 1 to claim 4, characterized in that the screen (5) consists of a material which is poorly wettable by the working fluid and that the screen is arranged separately from the condensate flowing back in the capillaries. BATH ORIGINAL ~ 1-0-9-Ä4-6X1-24-6 - Empty ropes