DE102005040239A1 - Weight-optimised heating pipe has thin walls together with container and cylinder and is set in support profile that is made from a light metal - Google Patents

Abstract

The weight-optimised heating pipe is made from a thin-wall and has a light container (1) that is set in a support profile (7) made from a light metal. The heating pipe container may be made up of a thin-walled smooth cylinder with an inner-lying capillary structure as well as a rippled thin walled pipe. The material used for the heating pipe container may be a metal with a high specific weight or a layer of heat conducting plastic. The support profile may be made, preferably, from a light metal and have different cross section with integrated flanges and may be combined with a second hollow profile.

Description

The The invention relates to a weight-optimized heat pipe according to the preamble of claim 1, wherein the heat pipe from a thin-walled, hermetically sealed container that consists in a support structure profile is embedded in light metal.

heat pipes (also known as heat pipes) have been around for several decades used in terrestrial applications as well as in space. heat pipes are closed mostly cylindrical vessels, in which one of the working temperature appropriate heat transfer fluid introduced which saturates a capillary structure on the insides of the vessel. Leading the heat pipe Heat too, evaporates the heat transfer fluid out of the capillary structure. By heat removal at another Point of the heat pipe condenses the resulting vapor and condensate is then passed through the capillary force of the mentioned Capillary structure promoted back to the evaporation zone. This process requires that the capillary structure is open, since the resulting from the heat supply Steam in the steam room escape and the condensate back into the Capillary structure must occur. Through the described process will heat transferred from the evaporation zone to the condensation zone, the heat of vaporization of the used heat carrier corresponds. As evaporation and condensation of the heat carrier at about the same temperature take place, lets heat transmitted with very low temperature differences. External energy supply to maintain the Circulation is not required.

basics Interpretation criteria for a heat pipe are the use of a suitable open capillary structure with high Capillarity, the choice of a heat transfer fluid with suitable thermodynamic properties in the desired Working temperature range and chemical compatibility of both Substances. For all heat pipes Care is taken to ensure that the heat transfer fluid used only with a structural material comes in contact to avoid corrosion problems. In many Applications are today used aluminum tubes with narrow axial grooves, which are advantageously produced by an extrusion process. The axial grooves are trapezoidal, to a close groove opening to obtain high capillarity and one possible huge Liquid cross section to To achieve reduction of the pressure drop. These heat pipes are usually made with ammonia operated, the cheap thermic Properties in the range of about -40 ° C and + 80 ° C and with aluminum and its alloys is compatible.

Especially at future Space applications, however, are heat pipes for higher working temperatures and also higher transmission powers needed for the Ammonia is no longer applicable. As an alternative, here is the known material combination copper / water. A major disadvantage these heat pipes is its high weight, caused by the three times higher density of the copper opposite Aluminum.

It gives more recent considerations, Plastics as heat pipe material while trying to reduce the low thermal conductivity of these materials by admixtures of metallic fibers or metal powder too improve.

It are copper / water heat pipes known, especially in the manufacturing process and in the design distinguish the capillary structure. This is therefore important for copper heat pipes since the known production of axial groove capillary through a Strangpressverfah reindeer with copper virtually impossible to accomplish is. In the known embodiments However, it is not addressed to a weight reduction of the container.

In US 6,293,333 B1 describes a heat pipe in which the capillary structure consists of closely meshed, corrugated wire mesh. The capillary structure is embedded in a smooth profile with a shrink fit. The heat transfer fluid is located on both sides of the corrugated capillary structure and wets the container wall. For a water / copper heat pipe, therefore, both the capillary structure and the container must be made of copper. Suggestions for reducing the weight of the container are not described.

A corrugated copper capillary structure is also in US 6,216,343 B1 described, wherein the corrugated structure consists of impermeable sheet material and is soldered to the container wall. Again, both the capillary structure and the container wall is wetted, so that both components must be made of copper. Suggestions for reducing the weight of the container are not described.

task

The present invention relates to a weight-optimized heat pipe, the weight reduction is achieved in that the actual heat pipe consists of very thin-walled heavy metal or plastic, which are embedded in a support profile of light metal. The thin-walled container for weight reasons, the working pressures during the heat pipe operation alone can not withstand, is held by the light metal support profile, so that a total of a weight Opti mated overall construction results.

Quoted writings

patent literature

• US 6,293,333 B1 Micro Channel Heat Pipe Having Wire Cloth Wick and Method of Fabrication
• US 6,216,343 B1 Method of Making Micro Channel Heat Pipe Having Corrugated Fin Elements

detailed Description of the invention

embodiments The invention are illustrated in drawings and will be described in more detail below.

It demonstrate

1 Cross section of the heat pipe container with two different capillary structures

2 : Heat pipe containers taken in various light metal support profiles

3 : Designs for the integration of the heat pipe container in the support profile

4 : Closure of the heat pipe container and the support profile

The inventive arrangement of a weight-optimized heat pipe, 1 consists of a mostly cylindrical, hermetically sealed and thin-walled container ( 1a . 1b ), which represents the actual heat pipe. This heat pipe container is embedded in differently designed support profiles made of light metal, 2 ( 6 to 9 ). For heat pipes which, for reasons of compatibility with the heat transfer fluid, must consist of high-density materials (eg copper / water), the walls ( 2a . 2 B ) of the container as thin as possible. Thin container walls are also suitable for heat pipes made of plastic, as this reduces the thermal resistance through the wall. On the inside of the container walls differently designed capillary structures are attached. Such capillary structures can pass through the thin wall (FIG. 2a ) itself so that axial capillary grooves ( 3a ) or a porous (eg sintered) material layer ( 3b ) is placed on the inner surface of the smooth container ( 2 B ) applied. The pores of the saturated with the heat transfer capillary structures are to the interior ( 4 ) of the heat pipe open to allow escape of the steam. In the following, the description of the arrangement according to the invention is based on the example of the axial groove tube (FIG. 1a ).

In 2 be made of light metal existing support profiles ( 6 to 9 ) with different cross sections and partly with integrated flanges, in which the heat pipe is embedded. Such a support profile is necessary because the thin-walled container alone only limited mechanical loads, especially pressure differences can accommodate. In order to produce lightweight support profiles, the material aluminum and its alloys are particularly suitable because of the low density of these materials, the various embodiments (US Pat. 6 to 9 ) are produced by the known extrusion process. Alternatively, for example, magnesium or beryllium and their alloys can be used. In a special form of the support profile ( 9 ) a second hollow profile ( 9a ) in order to bridge the height of the structure when embedding the heat pipes in sandwich structures. The advantage of the arrangements shown according to the invention lies in the fact that thin-walled heat pipe containers consisting of metals with high density, eg copper, or of poorly heat-conducting plastics are combined with a support profile made of light metal with correspondingly low weight. This results in a low total weight of the heat pipe.

In 3 Embodiments for admitting the thin-walled heat pipe containers ( 1 ) in the support profiles ( 6 to 9 ). In one method, the support profile ( 10 ) made of one piece, for example as an extruded profile, but which is open on one side to the heat pipe container ( 1 ). Then the profile ( 10 ) and the resulting seam ( 11 ) closed with a suitable method (eg laser beam or electron beam welding process). In another embodiment, the support profile consists of two halves ( 12a and 12b ), which, after the heat pipe container is inserted, are compressed. There are two seams ( 13a and 13b ), which are also closed by suitable joining methods. The outer diameter of the container and the inner diameter of the closed support profile are tuned so that both a good thermal contact is formed as well as the lubricity of both elements is ensured with each other to compensate for thermo-mechanical stresses due to the different thermal expansion coefficients. Thermal contact and sliding properties can be improved by using thermal grease.

In 4 Embodiments for closing the heat pipe container ( 1 ) as well as the Stitzprofils ( 7 ). Thereafter, the heat pipe container at both ends with a lid ( 15 ), wherein a lid is a filling tube ( 16 ) contains. Lid and filling tube are made with the container advantageous by a process without additives joined to prevent contamination in the interior of the heat pipe. In one embodiment, the support profile (FIG. 7 ) remain open at the sides, so that the outer surface of the heat pipe container is exposed to the ambient pressure. Should the internal pressure of the heat pipe be too high, the external grooves of the embodiment ( 1 ) of the container are filled with material (eg light structural foam). In another embodiment, the support profile with welded or soldered lids ( 14 ) so that the profile is hermetically sealed from the environment. In the cavity of the support profile either vacuum can be introduced, so that even at low internal pressures of the heat pipe, a good thermal contact between container ( 1 ) and support profile ( 7 ), or the cavity is depressed with a gas, so that at high internal pressures in the heat pipe, a corresponding external pressure prevails, which limits the burden on the thin-walled container.

Claims (17)

Weight-optimized heat pipe, characterized in that the actual heat pipe consists of a thin-walled and therefore light container, which is embedded in a support profile made of light metal, and thereby a total of a weight-optimized heat pipe is formed because the proportion of the container material is reduced and replaced by light metal of the support profile , heat pipe according to claim 1, characterized in that the heat pipe container both from a thin-walled smooth cylinder with internal capillary structure as well from a corrugated thin-walled Tube exists. heat pipe according to claim 2, characterized in that the material of the heat pipe container preferably of metals of high specific gravity or of poorly heat-conductive Kuststoff consists. heat pipe according to claim 2, characterized in that the effective pores the capillary structure to the interior of the heat pipe are open. heat pipe according to claim 1, characterized in that the support profiles preferably made of lightweight metal and different cross-sections also with integrated flanges. heat pipe according to claim 5, characterized in that the support profile combined with a second hollow profile. heat pipe according to claim 5, characterized in that the support profile as a laterally open structure is made to the heat pipe container introduce. heat pipe according to claim 7, characterized in that the support profile after inserting the heat pipe container is compressed and the resulting seam with a solder or welding processes is closed. heat pipe according to claim 5, characterized in that the support profile from two halves is produced, assembled after inserting the heat pipe container and through a suitable soldering or welding process getting closed. heat pipe according to claim 2 and claim 5, characterized in that the outer diameter of the heat pipe container and the inner diameter of the support profile are coordinated so that both a good thermal Contact as well as the lubricity the two elements are guaranteed to each other. heat pipe according to claim 10, characterized in that to improve the thermal contact as well as the lubricity of a thermal grease is used. heat pipe according to claim 2, characterized in that the heat pipe container is closed on both sides with a lid, in a lid a filling tube is integrated. heat pipe according to claim 12, characterized in that cover and filling tube with a joining process without additives. heat pipe according to claim 2 and claim 5, characterized in that the support profile is open at the side and the outside of the heat pipe container communicating with the environment. heat pipe according to claim 2, characterized in that the outer grooves of the corrugated heat pipe container be filled with a suitable material. heat pipe according to claim 5, characterized in that the support profile with inserted heat pipe hermetically sealed by end caps Environment is closed. heat pipe according to claim 16, characterized in that in the cavity of the support profile Vacuum prevails or a predetermined gas pressure can be set can.