JP2004506092A - Heat exchanger manufacturing method and heat exchanger obtained by this method - Google Patents

Abstract

The present invention relates to a method of manufacturing a heat exchanger, and more particularly to those used in the fields of electronics, telecommunications, aviation and / or space. For example, heat exchangers for onboard electronics, or heat discharge for onboard electronics, deployable or non-expandable radiators, or heat pipes, or fluid loops, or finned hollow cooling plates, etc. May be involved. The method comprises the steps of fabricating a core (1) according to a geometry adapted to assist in circulating the fluid and to assist heat exchange between the fluid and the environment of the heat exchanger; Inserting the material into the material of the base (8) in powder form; compressing the material of the base (8) around the core (1); selecting the core (1) by chemical means Dissolving in water.

Description

[0001]
The present invention relates to the field of heat exchanger manufacturing methods and the field of heat exchangers themselves.
[0002]
In particular, it may involve heat exchangers used in the fields of electronics, telecommunications and aerospace. For example, heat exchangers for on-board electronics, or cases for on-board electronics, or heat-dissipating, on-board or off-board radiators, or heat pipes, or fluid loops for on-board electronics Or a finned hollow cooling plate.
[0003]
In the field of space, as in the field of telecommunications, some electronic components and devices emit more and more heat. Extraction and removal of such heat fluxes by heat dissipation requires not only new materials with higher performance in terms of assembly with the divergent elements, but in particular the use of more sophisticated cooling and heat control techniques. For example, the heat output density emitted within a satellite can reach several kilowatts, so that forced or unforced circulation (fluid loops, heat pipes, etc.) and deployment of single or two-phase coolants It requires the use of cooling technology that utilizes a radiator.
[0004]
Cooling and heat control techniques are used in heat transport and heat exchangers that require complex and expensive processing and assembly techniques for fabrication. This is because these devices must exhibit good thermodynamic performance, as well as high airtightness levels. In addition, the demand for heat exchangers with ever greater exchange capacity has also resulted in increased fixed or deployed surface area. Such surface areas make the fabrication of these devices even more complex and expensive if high reliability is to be maintained.
[0005]
One object of the present invention proposes a simpler and therefore cheaper method of heat storage, heat transport and heat exchanger production than the prior art, while maintaining or even improving the reliability of the heat exchanger. That is.
[0006]
According to the invention, this object is achieved in a method of manufacturing a heat exchanger,
Fabricating the core according to a geometry adapted to store and circulate the fluid and further to assist heat exchange between the fluid and the environment of the heat exchanger;
Inserting the core into a base material in powder form;
Compressing the base material around the core;
・ Process of selectively dissolving the core by chemical means:
This is achieved by the method characterized by comprising:
[0007]
According to one characteristic unique to the invention, the base material is beryllium.
[0008]
According to another characteristic of the invention, the base material is made of beryllium or of an aluminum-beryllium alloy.
[0009]
According to an additional feature of the invention, the step of compressing the base material is produced by a heat-balancing press.
[0010]
According to another feature of the invention, the base material is extruded or co-extruded around the core.
[0011]
According to another feature of the invention, the core is made of a material compatible with the method of compression of the core, in particular copper for extrusion and steel for equilibrium pressing.
[0012]
According to an additional feature of the present invention, a core machining step is included to form the filaments on the outer surface.
[0013]
According to another characteristic unique to the invention, after the co-extrusion and removal of the core, a linear hollow profile of the heat pipe type is formed.
[0014]
According to an additional feature of the invention, the process of selectively dissolving the core by chemical means removes the core without eroding the base material and / or based on a micro-sized highly porous surface. It is manufactured in turn with one or more different solutions for the purpose of intentionally manufacturing on the inner or outer structure of the material.
[0015]
According to another feature of the invention, only the inner material, which is composed of two separate concentrically arranged materials and is centrally located, is selectively removed by chemical means and circulated in the piping network. A core composed of a plurality of different material assemblies is used, such as a tubular core, which leaves another material of the core to serve as an internal protection of the base material in the event of incompatibility with the incoming fluid.
[0016]
The meaning of the name core is that it is inserted into the base material before compression by means of an equilibrium press or extrusion, and its complementary shape is subsequently removed by selective chemical means into the base material. Means any remaining elements.
[0017]
Thus, according to the manufacturing method of the present invention, the heat transport and the heat exchanger are manufactured industrially by a very simplified processing and assembling process.
[0018]
Because the base material can be compressed around the entire core and in the form of a continuous mass, using a core creates a hollow interior structure without having to assemble the machined parts to form the interior structure be able to.
[0019]
It is the core itself that needs to be machined, which is easily accessible because it is accessible from the periphery, but not always easy inside the hollow structure.
[0020]
Manufacturing costs are reduced because the process of processing and assembling the different parts of the heat exchanger can be limited or even eliminated. However, in addition, the assembly surface is reduced or even eliminated, thus making the device more reliable. At this time, the heat exchanger manufactured by applying the present invention exhibits better mechanical and airtight properties.
[0021]
By creating a hollow internal structure directly during the compression of the material making up the heat exchanger, it is possible to obtain better reliability and higher cost / performance ratio due to the simplicity of the manufacturing method of the present invention become.
[0022]
The term "heat exchanger" includes elements that perform a function of storing, transporting, evaporating or flocculating a fluid as well as a combination thereof. These heat exchange functions are realized through conduction and heat dissipation. These functions are particularly well fulfilled by the thermal properties and surface coating of a composite of a metal matrix such as aluminum-beryllium.
[0023]
Aluminum-beryllium is a metal matrix composite in the sense that it is in the form of an aluminum matrix with beryllium particles dispersed therein. Therefore, strictly speaking, it is not the alloy itself.
[0024]
The production method according to the invention is therefore particularly advantageous, because aluminum-beryllium is very interesting because of its thermodynamic properties, but very difficult to process and assemble. In order to use it, special techniques, often expensive, such as brazing and welding, such as by laser or electron irradiation, must be used.
[0025]
Aluminum-beryllium is widely used in the thermal field, including in satellites, because it offers very high performance thermodynamic properties (very high stiffness at a density close to 2, very close to 240 W / m ゜, very high High thermal conductivity, and also particularly low coefficient of thermal expansion).
[0026]
In fact, this substance has its own properties:
Mechanical properties equivalent to, for example, alloy 6061;
・ Three times higher rigidity than aluminum alloy:
-24% lighter than aluminum alloy:
-Thermal conductivity is 25% higher than aluminum alloy:
-Thermal expansion coefficient is 40% lower than aluminum alloy:
-Specific heat is 75% higher than aluminum alloy:
• Very suitable for undergoing thermo-optic processing.
[0027]
Thus, an advantageous base material is a metal structure composite such as aluminum-beryllium, especially AlBeMet 162, a material developed by BRUSH WELLMAN.
[0028]
Its use is facilitated by the manufacturing method according to the invention, which fully meets the new demands of thermal relations in the space field. This is because the mass / performance ratio is decisive in the application field using the mounting device.
[0029]
By using an aluminum-beryllium composite material, the manufacturing method according to the invention can ensure that the following requirements are met in a reliable manner and without complex processing: inherent hermeticity, high mechanical strength, large Structural rigidity, and lightweight.
[0030]
By using the manufacturing method according to the present invention, the heat exchanger for the case for the on-board electronic device, the mouth of the case for the on-board electronic device, the heat discharge for the on-board electronic device, the radiator, the heat pipe, the fluid loop, the fin type Industrial production of a heat exchanger such as a hollow cooling plate becomes possible.
[0031]
It should be noted that the characteristics of the aluminum-beryllium composite material can be advantageously used for manufacturing an extremely lightweight heat sink.
[0032]
The production method according to the invention has the following advantageous features, alone or in combination:
An operation consisting of compressing the base material is produced by means of a heat-balancing press and / or extrusion;
The core is advantageously made of mild steel for equilibrium pressing and of copper for extrusion.
[0033]
The unique features of the hollow interior are given by the shape and cross section of the core, which is unique to the application in question. Thus, the core has a complementary shape of the desired internal structure. This shape is determined by the needs of the field of use. For example, the core can be solid or hollow, spherical, parallelepiped, or conical, triangular, star-shaped, with a cross-section that includes specific processing of grooves, filaments, and the like. The core may be formed to have linear and / or curved (eg, coiled) sections. The cores can also be interconnected or isolated, or arranged to form a two- or three-dimensional structure. The dimensions of the core are arbitrary and can be millimeters or meters, or sub-millimeters due to the precision of processing. The core can be made by any processing, molding or assembling method in a material that is compatible with the task of removing the core by a heat-balancing press (and / or extrusion) method and a selective chemical method.
[0034]
The cores can be subjected to specific surface treatments, preparations or specific assemblings (temperature, pressure, etc.) that make them compatible with the use of equipment in the manufacturing method according to the invention.
[0035]
Another object of the present invention is to provide a heat storage, transport and exchanger that has at least the same mechanical and thermal performance and hermetic levels as those of the prior art, but is less expensive.
[0036]
Another object of this is a heat exchanger formed by a base material compressed from powder, which corresponds to a mold in which a core selectively dissolved in the compressed base material remains. This is achieved by a heat exchanger characterized by including an internal structure.
[0037]
The heat exchanger according to the invention advantageously advantageously comprises the following features separately or in combination:
-The base material is aluminum-beryllium composite material;
・ Equipment listed in the table including the heat exchanger of the case for the mounted electronic device, the mouth of the case for the mounted electronic device, the heat discharge for the mounted electronic device, the radiator, the heat pipe, the fluid loop, and the fin type hollow cooling plate Corresponding to;
Having a hollow interior structure having at least one section corresponding to a core type having a particular processing, such as a filament;
Having a hollow internal structure with a pattern of sub-millimeter dimensions;
-It has an internal structure that is developed in three dimensions.
[0038]
According to a particular feature of the invention, the heat exchanger formed by the base material compacted from the powder corresponds to a mold in which the core selectively melted in the compressed base material remains. It has a hollow internal structure.
[0039]
According to another particular feature of the invention, the heat exchanger is an aluminum-beryllium composite.
[0040]
According to additional features of the invention, the heat exchanger is a heat exchanger for an on-board electronics case, a mouth of an on-board electronics case, a heat exhaust for an on-board electronics, a radiator, a heat pipe, a fluid loop, and a fin type. It corresponds to the device described in the list including the hollow cooling plate.
[0041]
According to another particular feature of the invention, the heat exchanger comprises a hollow internal structure having at least one section corresponding to a type of core having a specific processing, such as a filament.
[0042]
According to an additional feature of the invention, the heat exchanger has a hollow interior having a pattern of sub-millimeter dimensions.
[0043]
According to another particular feature of the invention, the heat exchanger has a three-dimensionally deployed internal structure.
[0044]
According to an additional feature of the invention, the base material has a thermal property and a heat exchange surface area of the beryllium particles of at least superficially to achieve a porous structure of micropores exhibiting excellent capillary retention properties. It is constituted by an aluminum-beryllium composite material increased by selective erosion.
[0045]
The present invention may be better understood with reference to the accompanying drawings.
FIG. 1 is a schematic view of the different steps (FIGS. 1a, b, c, d) of an embodiment of the manufacturing method according to the invention;
Fig. 2 shows an example of the geometry of the machined core (Fig. 2a) and a cross section of the hollow internal structure (Fig. 2b) left after removing this core;
FIG. 3 is another example of a heat exchanger obtained by the production method of the present invention shown in FIG. 1;
FIG. 4 shows an example of a cross section of a heat pipe having a plurality of radial flakes;
FIG. 5 is a diagram of the porous microstructure in the area of the heat pipe of FIG. 4 near the flakes.
[0046]
The production method according to the invention is described in detail below in a specific, non-limiting embodiment. According to this embodiment, a deployable radiator with an integrated serpentine network is achieved.
[0047]
As shown in FIG. 1, according to this embodiment, the manufacturing method according to the present invention has four steps.
[0048]
In a first step, a core 1 is prepared and processed (FIG. 1a). In this case, the core is made of copper, but other materials can be used. The core 1 is formed in a serpentine tube as shown in FIG. 1a. The core 1 is hollow tubular and has a longitudinally extending filament 2 on its outer surface (FIG. 2a). The outer diameter of the core 1 is about several millimeters (for example, 6 mm). The filament 2 forms a structure having a triangular cross section and a radially extending tip. Machining the filament 2 is easier than machining the filament on the inner surface of the cylindrical cavity, as would be the case if one did not attempt to fabricate its complementary shape directly on the base material.
[0049]
In the second step, the core 1 is embedded in the powder 4 of the base material (FIG. 1b). This material is aluminum-beryllium. The powder 4 is placed in a mold 6 and then subjected to a heating equilibrium press (FIG. 1b).
[0050]
After this process, a block 8 is obtained whose geometrical shape, determined by the shape of the mold 6, is advantageously already very close to the shape that the radiator will take in the final production.
[0051]
According to a third step, the block 8 is machined in order to reveal the point 10 of the core 1 (FIG. 1c).
[0052]
Advantageously, this process is facilitated by pre-orienting these tips 10 with X-ray imaging.
[0053]
In the fourth step, the core 1 is chemically eroded. To this end, an erosion liquid is circulated in the core and the core is dissolved by chemical erosion inside the block 8. The erosion liquid allows for selective ion transfer, for example, by perchloric acid tracks. This erosion liquid makes it possible to selectively dissolve the core 1 without eroding the block 8 and, in a more longitudinal counterpart, the hollow internal structure corresponding to the type of core 1 in this block 8. (See FIGS. 1d and 2b). It should be noted that under this condition, the erosion liquid does not come into contact with the material of the base 8 unless the entire core is almost dissolved. At this stage, the erosion rate ratio (e.g.,> 300) is such that the material of the base 8 is hardly eroded, making it possible to produce very fine geometric shapes.
[0054]
Depending on the type and function of the particular application area of interest, the core may be provided with a specific coating, for example a diffusion barrier to be compatible with different types of methods and the compression temperature of the base 8 material.
[0055]
Block 8 can then be machined from the outside if necessary.
[0056]
The manufacturing method according to the invention makes it possible to produce a large number of geometries of a particular piping network and arrangement in an inexpensive industrial manner.
[0057]
FIG. 3 shows another example of the heat exchanger to which the present invention is applied. This is a finned hollow plate 12, which is also referred to by those skilled in the art as "Finned Hollow Core Cold Plate". The plate 12 has a groove 14 of rectangular cross section (e.g., less than one square millimeter) extending longitudinally parallel to its major surface 16. The long side of the rectangular cross section is perpendicular to the main surface 16. These grooves 14 are typically separated from one another by a distance of a millimeter.
[0058]
FIG. 4 shows a heat pipe made in a specific longitudinal section of the radial flake type, made in an aluminum-beryllium block.
[0059]
FIG. 5 illustrates the details of the porous microstructure of the fin. The microscopic high porosity of this heat pipe profile makes it possible to create a dramatic increase in the heat exchange area by evaporation and to create an exceptional capillary action for the cooling fluid.

Claims (17)

In the method for manufacturing a heat exchanger,
Fabricating the core (1) according to a geometry adapted for storage and circulation of the fluid and further to assist heat exchange between the fluid and the environment of the heat exchanger;
Inserting the core (1) into the material of the base (8) in powder form;
Compressing the material of the base (8) around the core (1);
-Process of selectively dissolving the core (1) by chemical means:
A manufacturing method characterized by comprising: The method according to claim 1, wherein the material of the base (8) is beryllium. The method according to claim 2, wherein the material of the base (8) is made of beryllium or an aluminum-beryllium alloy. The method according to claim 1, wherein the step of compressing the material of the base is performed by a heating equilibrium press. 5. The method according to claim 1, wherein the material of the base is extruded or co-extruded around the core. 6. The core according to claim 1, wherein the core is made of a material compatible with the method of compressing the core, in particular copper for extrusion and steel for equilibrium pressing. Production method described in 1. 7. The method according to claim 1, further comprising the step of machining the core to form the filament on the outer surface. The method according to any one of claims 5 to 7, wherein after the co-extrusion and removal of the core, a heat pipe type linear hollow shape is formed. The process of selectively dissolving the core by chemical means removes the core without eroding the base (8) material and / or provides a micro-sized highly porous surface inside the base (8) material. 9. A method according to claim 1, characterized in that it is made using one or more different solutions for the purpose of making it intentionally on the outer structure. . Consisting of two separate materials arranged concentrically, only the centrally located internal material is selectively removed by chemical means, making it difficult to achieve compatibility with the fluid circulating in the pipeline. A core composed of an assembly of a plurality of different materials, such as a tubular core leaving another material of the core to play the role of protecting the material of the base (8), characterized in that it is used. 10. The production method according to any one of 1 to 9. In a heat exchanger formed by the base (8) material compressed from powder, a hollow corresponding to the mold in which the core (1) selectively melted in the compressed base (8) material remains. A heat exchanger comprising an internal structure. The heat exchanger according to claim 11, wherein the material of the base (8) is an aluminum-beryllium composite material. Compatible with devices listed in the table, including the heat exchanger for on-board electronics, the mouth of on-board electronics, heat dissipation for on-board electronics, radiators, heat pipes, fluid loops, and finned hollow cooling plates The heat exchanger according to claim 11, wherein the heat exchanger is used. 14. A hollow internal structure having at least one section corresponding to a type of core (1) having a specific processing, such as a filament (2). A heat exchanger according to item 1. 15. The heat exchanger according to any one of claims 11 to 14, characterized in that it has a hollow internal structure with a pattern (2) with dimensions of millimeters or less. The heat exchanger according to any one of claims 11 to 15, wherein the heat exchanger has an internal structure developed in three dimensions. The material of the base (8) is aluminum whose thermal properties and heat exchange surface area have been increased by selective erosion of beryllium particles to produce, at least on the surface, a microporous structure exhibiting excellent capillary retention properties. The heat exchanger according to any one of claims 11 to 16, characterized in that the heat exchanger is composed of a beryllium composite material.