CA2898052A1

CA2898052A1 - Heat-wing

Info

Publication number: CA2898052A1
Application number: CA2898052A
Authority: CA
Inventors: Yue Zhang
Original assignee: SHANGHAI DAZHI HEAT DISSIPATION TECHNOLOGY Co Ltd
Current assignee: SHANGHAI DAZHI HEAT DISSIPATION TECHNOLOGY Co Ltd
Priority date: 2013-01-16
Filing date: 2013-01-16
Publication date: 2014-07-24
Also published as: WO2014110746A1; RU2629805C2; AU2013374153A1; RU2014133102A; DE212013000272U1

Abstract

A heat fin comprises two side panels, a frame for connecting the two side panels, a capillary structural layer, and a phase change working medium, wherein the two side panels and the frame form a hollow thin-plate casing; the capillary structural layer is closely attached to an inner wall of the casing; the phase change working medium is sealed in the casing; a part of an edge of each side panel or a part of the frame serves as an evaporation area; and the rest part of each side panel or the rest part of the casing serves as a condensation area. Due to the adoption of the heat fin, the area of a steam conveying passage, the reflux width of the liquid working medium, and the direct heat dissipation area of the condensation area are increased, the distance from the center of the evaporation area to the edge of the evaporation area is shortened, the heat conduction limit is greatly improved, and a higher heat flow density is obtained.

Description

English translation of PCT/CN2013/070572 HEAT-WING
TECHNICAL FIELD
The present invention relates generally to phase-change heat exchangers, and particularly to a heat-wing.
BACKGROUND
Compared to high thermal conductivity solid metal blocks, phase-change heat exchangers have higher equivalent thermal conductivities and better heat dissipation performance.
They are widely used because of a variety of advantages, such as a high thermal conductivity and good temperature uniformity. These advantages are realized by liquid working media sealed in the heat exchangers, on the phase transition of which the heat exchangers rely for heat transfer. Currently, heat pipes and vapor chambers are two types of commonly used phase-change heat exchangers.
Referring to FIG. 1, a typical heat pipe is composed of a housing 11, a capillary structure 12 and a phase-change working medium 13 hermetically sealed in the housing. Fabrication of the heat pipe generally includes: vacuuming the housing and partially filling the housing with the working medium 13;
impregnating the capillary structure 12, which is closely attached to an inner surface of the housing 11, with the working medium 13; and sealing he housing. One end of the heat pipe serves as an evaporator section 14, while the other end acts as a condenser section 15. When the evaporator section 14 is being heated, the working liquid medium 13 in the capillary structure 12 vaporizes into a vapor working medium 16. The vapor working medium subsequently flows through ducts 17 under the action of a differential pressure and enters the condenser section 15, where it condenses back to the liquid working medium 13, releasing the heat. Thereafter, the restored liquid working medium 13 flows along the capillary structure 12 under a capillary pressure and returns to the evaporator section 14. With the 'repetition of this cycle, heat 18 is continuously transferred from the evaporator section 14 to the 'condenser section 15 and thereby realizes heat dissipation. However, as the heat pipe has a relatively ,small diameter, the vapor transport occurs therein in a nearly one-dimensional, linear manner. Moreover, limited by the narrow ducts for vapor transport and a minimal flow-back passage width of the liquid working medium, the heat pipe tends to reach its heat transfer limit before operating at the optimal performance level. As an improved type of heat pipe, a vapor chamber generally includes a base plate, a cover, a capillary structure and a working medium. A central area of the base plate serves as the evaporator section and the cover as the condenser section. In the vapor chamber, vapor is transported in English translation of PCT/CN2013/070572 a nearly two-dimensional, planar manner. Compared with heat pipe, the vapor chamber provides a larger vapor passage area and a larger liquid working medium flow-back passage width, thus ensuring better temperature uniformity than that of a heat pipe. However, as a relatively large evaporator center-to-edge distance tends to lead to early dry-out of the evaporator section, the vapor chamber is also associated with the low heat transfer limit problem. Therefore, there exists a need for a novel phase-change heat exchanger with a large vapor passage area, large working medium flow-back passage width and short evaporator center-to-edge distance.
SUMMARY OF THE INVENTION
Technical Problem As a heat pipe has a relatively small diameter, the vapor transport occurs therein in a nearly one-dimensional, linear manner. Moreover, limited by the narrow ducts for vapor transport and a minimal flow-back passage width of the liquid working medium, the heat pipe tends to reach its heat transfer limit before operating at the optimal performance level. As a relatively large evaporator center-to-edge distance tends to lead to early dry-out of the evaporator section, a vapor chamber is also associated with the low heat transfer limit problem. Therefore, there exists a need for a novel phase-change heat exchanger with a large vapor passage area, large working medium flow-back passage width and short evaporator center-to-edge distance.
Solution for Addressing the Problem Technical Solution It is therefore an objective of the present invention to provide a phase-change heat exchanger with a large vapor passage area, large working medium flow-back passage width, short evaporator center-to-edge distance, large condenser heat dissipation area and high heat transfer limit.
In pursuit of the above objective, the present invention provides a heat-wing, which includes: two plates and a frame connecting the two plates, the two plates and the frame constituting a thin plate-shaped hollow housing; a capillary structure layer attached to an inner surface of the housing; and a phase-change working medium sealed in the housing.
Wherein, a portion of a periphery of one of the two plates or a portion of the frame serves as an evaporator

2 English translation of PCT/CN2013/070572 section of the heat-wing, and the rest portion of the housing serves as a condenser section of the heat-wing.
In one preferred embodiment, materials that the housing can be fabricated from include copper, aluminum, stainless steel metal and alloys thereof, and other high conductivity materials.
In another preferred embodiment, the capillary structure layer may be a single-or multi-layer structure made of sintered powder(s), wire lattices, grooves etched into the shell, fibers, coated or grown carbon nanowalls, carbon nanotubes or carbon nanocapsules, other coated or grown nano-or micro-order thin organic or inorganic layer(s), or any combination of the above, or any other suitable structure providing capillary attraction.
In a further preferred embodiment, materials that may be used as the phase-change working medium include water and other liquids, low melting point metals, carbon nanocapsules, other nanoparticles, mixtures of the above materials, and other materials having gas-liquid phase transition at a temperature within the operating temperature range of the heat-wing.
In yet another preferred embodiment, the two plates are parallel or substantially parallel to each other.
Each of the plates may assume a rectangular shape or any other shape.
In yet a further preferred embodiment, the heat-wing has a cross-sectional area of a section near to the evaporator section that is larger than a cross-sectional area of a top section of the heat-wing. Alternatively, the cross-sectional area of the section near to the evaporator section may also be smaller than or equal to the cross-sectional area of the top section.
In another preferred embodiment, the heat-wing may be evacuated to a certain degree of vacuum, and may accordingly further include a support or connection structure disposed between the two plates according to the mechanical strength of the housing and positive and negative pressures to be applied =thereto. The support or connection structure may assume the shape of a dot, a line or a sheet.
in a further preferred embodiment, the heat-wing may further include a fin.
In yet another preferred embodiment, the heat-wing and/or the fin may be coated with a black-body radiator material.
In a further preferred embodiment, the heat-wing may further include a hose for vacuuming and liquid filling.

3 English translation of PCT/CN2013/070572 An array of the heat-wings may be disposed on a heat source.
Technical Effects of the Invention Technical Effects Compared with the prior art, the present invention has the following advantages: as the heat-wing of the present invention is a hermetically sealed plate-shaped hollow housing having a length and width both much greater than its thickness, by bringing a portion of a periphery of one of the two plates or a portion of the frame, which has a limited area relative to the whole housing area, into contact with the surface of the heat source so as to make it serve as an evaporator section, vapor is transported in a nearly two-dimensional, planar manner in the heat-wing, which results in a large passage area for vapor transport and ensures a high temperature uniformity;
since the gap between the two plates is very small, a very short evaporator section center-to-edge distance can be achieved, thereby addressing the issue of early dry-out of the evaporator section central area;
by using the two relatively large plates as a condenser section, the heat-wing ensures an extremely large condenser section area, which facilitates the heat dissipation, and provides a large working medium flow-back passage width which is about two times the width of the heat-wing and allows a large flux of the working medium.
The heat-wing has a greatly improved heat transfer limit and is hence capable of achieving a higher heat flux density over the prior art.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows a schematic cross-section view of a conventional hot pipe.
FIG. 2 shows a three-dimensional view of a heat-wing in accordance with a first embodiment of the present invention.
FIG. 3 shows a schematic cross-sectional view taken along the line A-A of FIG.
2.
FIG. 4 shows a schematic cross-sectional view of a heat-wing in accordance with a second embodiment of the present invention.
FIG. 5 shows a schematic cross-sectional view of a heat-wing in accordance with a third embodiment of the present invention.
'FIG. 6 shows a schematic cross-sectional view of a heat-wing in accordance with a fourth embodiment

4 English translation of PCT/CN2013/070572 of the present invention.
FIG. 7 shows a schematic cross-sectional view of a heat-wing in accordance with a fifth embodiment of the present invention.
FIG. 8 shows a schematic cross-sectional view of a heat-wing in accordance with a sixth embodiment of the present invention.
FIG. 9 shows a three-dimensional view of a heat-wing array in accordance with a seventh embodiment of the present invention.
FIG. 10 shows a schematic cross-sectional view of a heat-wing array in accordance with an eighth embodiment of the present invention.
FIG. 11 is an exploded three-dimensional view of FIG. 10.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Most Preferred Embodiment of the Present Invention FIGs. 10 and 11 show an eighth embodiment of the present invention, which is also the most preferred embodiment of the present invention. As illustrated, in this embodiment, a plurality of J-shaped heat-wings of FIG. 6 are arranged in an array and disposed on a heat source, with the top surface of the heat source being totally covered. Each heat-wing of the array of this embodiment is bent to project laterally from the heat source and is thus particularly suitable for applications where there exists a height limitation.
Other Embodiments of the Present Invention The forgoing objectives, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. It is to be understood that the invention is not limited to the embodiments described herein and the embodiments are provided to enable those skilled in the art to understand the ,present invention. In addition, the technical terms used herein could be construed in the broadest sense without departing from the spirit and nature of the invention. The use of the same reference symbols in different drawings indicates similar or identical items.
A first embodiment of the present invention is shown in FIGs. 2 and 3. As illustrated, the heat-wing of

5 English translation of PCT/CN2013/070572 the present invention includes two plates 21 and a frame 22 and 23 connecting the two plates 21, which constitute a plate-shaped hollow housing 2, a capillary structure layer 12 which is closely attached to an inner surface of the housing 2; and a phase-change working medium 13 hermetically sealed in the housing 2. A portion of the frame 22 and 23, such as a portion of the bottom frame section 23 comes in contact with a heat source 3, and thus functions as an evaporator section, while the rest portion of the housing 2 acts as a condenser section. Alternatively, it is also possible to only use the two plates 21 to serve as the condenser section.
Each of a length and a width of the heat-wing is much greater than a thickness of the heat-wing. As a result, the heat-wing possesses a large passage area for vapor transport, ensuring high temperature uniformity. Additionally, since the gap between the two plates 21 is very small, bringing a portion of a periphery or a portion of the frame 23, which has a limited area relative to the whole area of thin plate-shaped housing 2, into contact with the heat source 3 so as to make it serve an evaporator section realizes a very short evaporator center-to-edge distance, thereby addressing the issue of early dry-out of the evaporator section central area. Moreover, by using the two relatively large plates of the housing to serve as a condenser section, the heat-wing ensures a large condenser section area, which facilitates heat dissipation and vapor condensation. In addition, this feature allows a larger passage width for the flow-back of the working medium 13 and hence increases the flux of the medium. For these reasons, the heat-wing has a greatly improved heat transfer limit and is hence capable of achieving a higher heat flux density.
Materials that the housing 2 can be fabricated from include copper, aluminum, stainless steel and alloy thereof, and other high conductivity materials, each of which can ensure a good heat transfer performance of the heat-wing.
The capillary structure layer 12 may be a single- or multi-layer structure made of sintered powder(s), wire lattices, grooves etched into the shell, fibers, coated or grown carbon nanowalls, carbon nanotubes or carbon nanocapsules, other coated or grown nano- or micro-order thin organic or inorganic layer(s), or any combination of the above, or any other suitable structure providing capillary attraction.
Materials that may be used as the working medium 13 sealed in the heat-wing include water and other liquids, low melting point metals, carbon nanocapsules, other nanoparticles, mixtures of the above materials, and other materials having gas-liquid phase change at a temperature within the operating temperature range of the heat-wing.

6 English translation of PCT/CN2013/070572 The heat-wing may be evacuated to a certain degree of vacuum, and may accordingly further include a support or connection structure (not shown) disposed between the plates 21.
The support or connection structure may be designed according to the mechanical strength of the housing 2 and positive and negative pressures to be applied thereto. The support or connection structure may assume the shape of a dot, a line, a sheet or any other shape. Further, in some alternative embodiments in which the housing 2 has a sufficient strength to sustain the required load, the heat-wing may not include the support or connection structure.
In the first embodiment, the two plates 21 are in parallel to each other, and a bottom section of the housing 2 that is in close contact with the heat source 3 has a cross-sectional width greater than that of a top section of the heat-wing. In some alternative embodiments of the invention, the plates 21 may be entirely parallel to each other, or a bottom width of the heat-wing may be different from a top width thereof.
The heat-wing may further include auxiliary features arranged on the plates, such as, for example, fin(s) (not shown), hose(s) for vacuuming and liquid filling (not shown) and the like. The fin(s) is capable of facilitating the dissipation of heat from the interior of the heat-wing. In addition, for a better heat transfer performance, the heat-wing and/or the fin(s) can be coated with a black-body radiator material in order to further promote heat dissipation from the interior of the heat-wing and fin(s). The hose(s) can be used in creating a desired vacuum condition for the working medium in the heat-wing. It is to be noted that the heat-wing may not include the fin(s) and hose(s) in some alternative embodiments.
Heat-wings constructed in accordance with second to sixth embodiments of the invention are respectively shown in FIGs. 4 to 8. As demonstrated in FIGs. 4 to 6, the heat-wing of the present invention may have different cross-sectional shapes of a bottom section thereof, such as, a convex arc shape of a bottom section of the plate 21 proximal to the evaporator section shown in FIG. 4, a concave arc shape shown in FIG. 5, and a substantially rectangular shape shown in FIG. 6. In addition, the bottom section may be slightly wider than the top section of the heat-wing. Alternatively, it can be appreciated that the bottom section of the heat-wing may also have a width the same or smaller than that of the top section of the heat-wing.
As demonstrated in FIGs. 4 to 8, the top frame section 22 may be closed by different techniques and thus have different shapes, such as, for example, an arc shape shown in FIG. 4, a linear shape shown in FIG.
5, a shape with a protrusion shown in FIG. 6 and a substantially "L" shape shown in FIG. 8.
As demonstrated in FIGs. 4 to 8, and 10, the heat-wing may have a variety of overall shapes, such as, for

7 English translation of PCT/CN2013/070572 example, the shape of a wedge as shown in FIG. 7 with the two plates 21 being substantially parallel to each other. The heat-wing may also be formed into curved shapes as shown in FIGs. 5 and 6.
In addition, as demonstrated in FIG. 8, the heat-wing may have a portion of a periphery of one plate 21 serving as the evaporator section.
Further, as demonstrated in FIG. 10, the heat-wing may be bent to project laterally in response to a height limitation.
FIG. 9 shows a seventh embodiment of the present invention. As illustrated, in this embodiment, a plurality of the heat-wings of FIG. 2 are arranged in an array and disposed on a heat source, totally covering the top surface of the heat source. Such array arrangement expands the two-dimensional phase-change heat transfer into a three-dimensional space and hence can achieve a higher heat flux density.
FIGs. 10 and 11 show an eighth embodiment of the present invention. As illustrated, in this embodiment, a plurality of the J-shaped heat-wings of FIG. 6 are arranged in an array and disposed on a heat source, totally covering the top surface of the heat source. Differing from the seventh embodiment, each heat-wing of the array of this embodiment is bent to project laterally and is thus particularly suitable for applications where there exists a height limitation.
It is to be understood that changes and modifications may be made by those having ordinary skill in the art after reviewing the above description. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.
Industrial Applicability The application of the present invention in industries can not only greatly reduce the dimension and height of heat dissipation apparatuses but also highly improve the heat flux density of heat dissipation apparatuses.
Heat dissipation apparatuses incorporating the heat-wing(s) can be used for the heat dissipation of high-power semiconductor devices like high-power transistors, high-power semiconductor laser devices, high-power light emitting diodes (LEDs), high-power central processing units (CPUs), high-power graphics processing units (GPUs) and so on.
In occasions where heat dissipation apparatuses incorporating the heat-wing(s) is used, all water cooling methods can be replaced by air cooling methods, and active cooling methods can be replaced by passive cooling methods.

8 English translation of PCT/CN2013/070572 Heat dissipation apparatuses incorporating the heat-wing(s) can enable the reduction of height of a tower case of a desktop computer to nearly a thickness of a laptop computer.

9

Claims

WHAT IS CLAIMED IS:

1. A heat-wing, comprising:
two plates and a frame connecting the two plates, the two plates and the frame constituting a thin plate-shaped hollow housing;
a capillary structure layer attached to an inner surface of the housing; and a phase-change working medium sealed in the housing;
wherein a portion of a periphery of one of the two plates or a portion of the frame serves as an evaporator section of the heat-wing, and the rest portion of the housing serves as a condenser section of the heat-wing.

2. The heat-wing of claim 1, wherein the two plates are parallel or substantially parallel to each other.

3. The heat-wing of claim 1, wherein a support or connection structure is disposed between the two plates.

4. The heat-wing of claim 1, wherein when a portion of the frame serves as the evaporator section, the frame is in contact with a surface of the heat source and the rest portion of the heat-wing extends outwardly.

5. The heat-wing of claim 1, wherein when a portion of a periphery of one of the two plates serves as the evaporator section, said portion of the periphery is in parallel with and in contact with a surface of the heat source and the rest portion of the heat-wing extends outwardly.