US20150219401A1

US20150219401A1 - Heat-wing

Info

Publication number: US20150219401A1
Application number: US14/335,649
Authority: US
Inventors: Yue Zhang
Original assignee: SHANGHAI DAZHI HEAT DISSIPATION TECHNOLOGY Co Ltd
Current assignee: SHANGHAI DAZHI HEAT DISSIPATION TECHNOLOGY Co Ltd
Priority date: 2012-01-18
Filing date: 2014-07-18
Publication date: 2015-08-06

Abstract

A heat-wing includes: a sealed hollow chamber including two plates and a frame connecting the two plates; a capillary structure layer closely attached to an inner surface of the chamber; and a phase transition working medium sealed in the chamber. A portion of the frame or a portion of a periphery of one of the two plates serves as an evaporation area of the heat-wing, and the rest portion of the chamber serves as a condensation area of the heat-wing. The heat-wing has an increased vapor passage area, liquid working medium flow-back passage width and condenser heat transfer area and a reduced evaporator center-to-edge distance, and is hence capable of achieving a great improvement in heat transfer limit and heat flux density.

Description

TECHNICAL FIELD

The present invention relates generally to phase-change heat exchangers, and particularly to a heat-wing and use thereof.

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 hollow cylindrical chamber 11, a capillary structure 12 and a phase transition working medium 13 hermetically sealed in the chamber. Fabrication of the heat pipe generally includes: vacuuming the chamber and partially filling the chamber with the working medium 13; impregnating the capillary structure 12, which is closely attached to an inner surface of the chamber 11, with the working medium 13; and sealing the chamber. One end of the heat pipe serves as an evaporation area 14 which is brought in contact with a heat source for extracting heat from the source, while the other end acts as a condensation area 15 for dissipating heat, directly, or with the aid of auxiliary equipment such as fans for a higher efficiency. The rest section of the heat pipe between the evaporator and condensation areas 14 and 15 is referred to as an adiabatic section. When the evaporation area 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 condensation area 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 evaporation area 14. With the repetition of this cycle, heat 18 is continuously transferred from the evaporation area 14 to the condensation area 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, Chinese patent publication No. CN201364059Y discloses a vapor chamber, or called a flat plate heat pipe. As shown in FIG. 2, each of the vapor chambers 42 and 42′ uses its two plates to serve as working plates. In the vapor chamber, vapor is transported in 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, during use of this kind of vapor chambers 42 and 42′, heat is transferred successively through a heat conduction piece 41 and clamps 412 for fixing the vapor chambers which are arranged in a direction perpendicular to the plane of the heat source and finally reaches the plates of the vapor chambers 42 and 42′. In such a configuration, the distance from the heat source to the vapor chambers is too long, with an average distance equal to a thickness of the heat conduction piece 41 plus half of a height of the clamp, while a total heat conduction width in the clamps 412 is too short, which is only a sum of the widths of the two clamps 412, thereby results in a relatively high thermal resistance.
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

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, a first aspect of the present invention provides a heat-wing, which includes: a sealed hollow chamber, including two plates and a frame connecting the two plates; a capillary structure layer closely attached to an inner surface of the chamber; and a phase transition working medium sealed in the chamber.
Wherein, a portion of the frame or a portion of a periphery of one of the two plates is in direct contact with a heat source and thereby serves as an evaporation area of the heat-wing, and the rest portion of the chamber that is not in contact with the heat source serves as a condensation area of the heat-wing.
Wherein, each of a length and a width of the chamber is much greater than a thickness of the chamber.
In one preferred embodiment, materials that the chamber can be fabricated from include copper, aluminum, stainless steel metal and alloys thereof, high thermal conductivity ceramics, and other high thermal 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 chamber, 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 transition 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.
In a further preferred embodiment, each of the plates may assume a rectangular shape or any other shape, and may be flat or curved.
In yet a further preferred embodiment, the heat-wing has a cross-sectional area of a section near to the evaporation area that is larger than a cross-sectional area of an upper section of the heat-wing. Alternatively, the cross-sectional area of the section near to the evaporation area 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 chamber and positive and negative pressures to be applied thereto.
In a preferred embodiment, 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.
In a preferred embodiment, an array of the heat-wings may be disposed on a heat source.
Another aspect of the present invention provides an apparatus which includes a heat-generating component and at least one heat-wing each including: a sealed hollow chamber including two plates and a frame connecting the two plates; a capillary structure layer closely attached to an inner surface of the chamber; and a phase transition working medium sealed in the chamber, wherein each heat-wing has a portion of the frame or a portion of a periphery of one of the two plates thereof in direct contact with the heat-generating component and thereby serving as an evaporation area of the heat-wing, and the rest portion of the chamber that is not in contact with the heat-generating component serves as a condensation area of the heat-wing, wherein each of a length and a width of the chamber of each heat-wing is much greater than a thickness thereof.
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 chamber 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 chamber area, into contact with the surface of the heat source so as to make it serve as an evaporation area, 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 evaporation area center-to-edge distance can be achieved, thereby addressing the issue of early dry-out of the evaporation area central area;
by using the two relatively large plates as a condensation area, the heat-wing ensures an extremely large condensation 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 schematic cross-section view of a conventional vapor chamber.

FIG. 3 shows a three-dimensional view of a heat-wing in accordance with a first embodiment of the present invention.

FIG. 4 shows a schematic cross-sectional view taken along the line A-A of FIG. 3.

FIG. 5 shows a schematic cross-sectional view of a heat-wing in accordance with a second embodiment of the present invention.

FIG. 6 shows a schematic cross-sectional view of a heat-wing in accordance with a third embodiment of the present invention.

FIG. 7 shows a schematic cross-sectional view of a heat-wing in accordance with a fourth embodiment of the present invention.

FIG. 8 shows a schematic cross-sectional view of a heat-wing in accordance with a fifth embodiment of the present invention.

FIG. 9 shows a schematic cross-sectional view of a heat-wing in accordance with a sixth embodiment of the present invention.

FIG. 10 shows a three-dimensional view of a heat-wing array in accordance with a seventh embodiment of the present invention.

FIG. 11 shows a schematic cross-sectional view of a heat-wing array in accordance with an eighth embodiment of the present invention.

FIG. 12 is an exploded three-dimensional view of FIG. 11.

DETAILED DESCRIPTION

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. 3 and 4. As illustrated, the heat-wing of the present invention includes a chamber 2 which is essentially a hollow plate-shaped structure including two plates 21 and a frame 22 and 23 connecting the two plates 21. The heat-wing further includes a capillary structure layer 12 which is closely attached to an inner surface of the chamber 2, and a phase transition working medium 13 hermetically sealed in the chamber 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 evaporation area, while the rest portion of the chamber 2 acts as a condensation area. Alternatively, it is also possible to use a portion of a periphery of one of the two plates 21 to serve as the evaporation area.
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 (i.e., the thickness of the heat-wing) is very small, bringing a portion of a periphery of one plate 21 or a portion of the frame 23, which has a limited area relative to the whole area of thin plate-shaped chamber 2, into direct contact with the heat source 3 so as to make it serve an evaporation area realizes a very short evaporator center-to-edge distance, thereby addressing the issue of early dry-out of the evaporation area central area. Moreover, by using the two relatively large plates of the chamber to serve as a condensation area, the heat-wing ensures a large condensation 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.
Herein, the length of the heat-wing, i.e., the length of the hollow chamber 2, is defined as a dimension projecting away from a plane of the heat source, i.e., the length is a distance from a side of the plate 21 contacting the heat source 3 to the opposite side of the plate 21 which is farthest from the heat source 3. Therefore, for a flat plate 21 (e.g., that shown in FIG. 8), the distance is the length of a straight line, and for a curved plate 21 (e.g., those shown in FIGS. 4 to 7, and 11), the distance is the length of a curve. The width of the heat-wing, i.e., the width of the hollow chamber 2, is defined as a dimension extending in parallel to the plane of the heat source, i.e., the length of each plate 21 extending perpendicular to the planes of FIGS. 4 to 8, and 11. Furthermore, a periphery of the plate 21 refers to an area extending from the edge of the plate toward the center of the plate by a very short distance relative to a length or a width of the plate. Take a square flat plate as an example, the periphery of such a plate is a hollow square extending from the four sides of the plate by a very short distance toward the center of the plate, and the very short distance should be much smaller than the side length of the square flat plate. If the plate is circular, then the periphery of the plate is ring shaped. Those skilled in the art shall appreciate that the periphery of the plate could have different shapes depending on the shape of the plate.
The length, width and thickness of the heat-wing may vary with specific needs of different applications, but a common requirement for these dimensions is that both the length and width should be much greater than the thickness, e.g., at least one order of magnitude greater. The present invention is, however, not limited in this regard, because those skilled in the art may design suitable length, width and thickness for the heat-wing without departing from the spirit of the present invention, based on their knowledge.
Materials that the chamber 2 can be fabricated from include copper, aluminum, stainless steel and alloy thereof, high thermal conductivity ceramics, and other high thermal 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 chamber, 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.
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 chamber 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 chamber 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 except in their bottom sections, and a bottom section of the chamber 2 that is in close contact with the heat source 3 is thicker than an upper section of the heat-wing. In some alternative embodiments of the invention, the plates 21 may be entirely parallel to each other, or the chamber 2 may have different thicknesses in its top and bottom sections.
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. 5 to 9. As demonstrated in FIGS. 5 to 7, 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 evaporation area shown in FIG. 5, a concave arc shape shown in FIG. 6, and a substantially rectangular shape shown in FIG. 7. In addition, the bottom section of the chamber may be slightly thicker 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 thickness the same or smaller than that of the top section of the heat-wing.
As demonstrated in FIGS. 4 to 9, the frame of the heat-wing may either include a bottom frame section, two lateral frame sections and a top frame section (as shown in FIGS. 4 to 7, and 9), or only includes a bottom frame section and two lateral frame sections but no top frame section (as shown in FIG. 8). In the latter case, the hollow chamber may be closed at the top by directly connecting top portions of the two plates 21. Further, as shown in FIGS. 4 to 7, and 9, 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. 5, a linear shape shown in FIG. 6, and a shape with a protrusion which may be formed at different positions as shown in FIGS. 7 and 9.
As demonstrated in FIGS. 5 to 9, and 11, the heat-wing may have a variety of overall shapes, such as, for example, the shape of a wedge as shown in FIG. 8 and the shapes with bent plates 21 as shown in FIGS. 6 and 7.
In addition, as demonstrated in FIG. 9, the heat-wing may have a portion of a periphery of one plate 21 being taken in contact with the heat source 3 to serve as the evaporation area.
Further, as demonstrated in FIG. 11, the heat-wing may be bent to project laterally in response to a height limitation.
FIG. 10 shows a seventh embodiment of the present invention. As illustrated, in this embodiment, a plurality of the heat-wings of FIG. 3 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. 11 and 12 show an eighth embodiment of the present invention. As illustrated, in this embodiment, a plurality of the J-shaped heat-wings of FIG. 7 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 from the heat source 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 heat-wing of the present invention can be applied in any apparatus including a heat-generating component needing heat dissipation, simply by bringing a portion of a periphery of one plate 21 or a portion of the frame 22 and 23 in direct contact with the surface of the heat-generating component to make it serve as an evaporation area. As the heat dissipation mechanism of the heat-wing has been explained above, further description of it is omitted here.
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.
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.
In order for a better understanding of the high heat dissipation performance of the heat-wing of the present invention and its application prospect in the heat transfer field, comparisons are made between conventional heat pipe and vapor chamber and the heat-wing of the present invention.
Comparison Between Heat-Wing and Conventional Heat Pipe
The exemplified conventional heat pipe is a commonly used Φ6 mm×200 mm heat pipe with an evaporation area, having a width of about 4 mm and in contact with a heat source. The heat-wing has a thickness of 6 mm, a width of 100 mm, a height of 100 mm, and also an evaporation area width of 4 mm. A central processing unit (CPU) with a typical size of 35 mm×35 mm, the most common kind of device needing heat dissipation, is exemplified as the heat source. Therefore, both the heat pipe and the heat-wing have an evaporation area of 4 mm×35 mm.
The performance of the two heat dissipaters was assessed on the following five metrics:
1. Boiling limit: If the radial heat flux density in the evaporation area of the heat pipe becomes too high, the liquid in the evaporator wick boils. And when the radial heat flux density reaches a threshold value, across a long length from the adiabatic section to the end of the evaporation area, the liquid in the evaporator wick is in a critical boiling state and generates a great amount of bubbles which blocks wick pores, thus reducing or destroying the capillary attraction of the wick. This causes the amount of the liquid flowing back to the evaporation area to be lower than its amount evaporated therein per unit time. As a result, the end of the evaporation area is dried out, thus partially disabling the evaporation area.
Compared to the heat pipe which has the length from the adiabatic section to the end of the evaporation area, i.e., the length the working fluid is transported, of 35 mm, thanks to the two plates which functions not only as a condensation area but also as a means for liquid transport, the length of the heat-wing from the adiabatic section to the center of the evaporation area is 2 mm. That is, a maximum liquid transport length of the heat-wing is 2 mm, lower than 6% of that of the heat pipe. Therefore, the heat-wing is nearly immune from the boiling limit issue.
2. Sonic limit: The flowing behavior of vapor in the heat pipe is similar to that of gas in a De Laval nozzle. When the evaporation area of the heat pipe is kept at a certain temperature, lowering the temperature of the condensation area can result in an increase in the vapor velocity and hence an increase in the heat transfer rate. However, when the velocity of vapor exiting the evaporation area increases to as high as the local speed of sound, it will not increase any more to lead to further rise in the heat transfer rate, even upon the condensation area temperature being further lowered. This choked flow condition is called the sonic limitation.
Compared to the heat pipe which has a vapor exit area of the evaporation area (i.e., the inner cross-sectional area of the heat pipe) of 12 mm², the evaporator vapor exit of the heat-wing is a hollow space flaring from a semicircle with an area of about 210 mm²(35 mm×3.14/2×4), higher than 1750% of the 12 mm²of the heat pipe, let alone that the cross sectional area of the space proportionally increases with the length outwardly from the semicircle. Therefore, the heat-wing has no limit for vapor flux and it is hence immune from the sonic limit issue.
3. Entrainment limit: In the heat pipe, the vapor and liquid move in opposite directions and hence confront at the liquid-vapor interface. Under the action of the oppositely flowing vapor, the surface of the liquid waves, and at a high vapor velocity, the surficial liquid will be sheared into small droplets and entrained into the vapor flowing toward the condensation area. If the entrainment becomes too great, the liquid flowing back to the evaporation area will be insufficient in amount or even be cut off halfway in the wick, thus leading to dry-out of the evaporation area and operation cessation of the heat pipe. The heat transfer rate at which this occurs is called the entrainment limit.
As described above, compared to the vapor passage area of the heat pipe which is 12 mm², that of the heat-wing is a hollow space with a semicircular cross sectional area proportionally increasing outwardly from an area of about 210 mm², higher than 1750% of that of the heat pipe. Therefore, for the same condition, the vapor flux and heat flux density in the adiabatic and condensation areas of the heat-wing are much lower than 6% of those of the heat pipe and the heat-wing is hence free from the entrainment limit issue.
4. Capillary limit: during the operation of the heat pipe, when the sum of the liquid and vapor pressure drops equates to the maximum capillary pressure that the wick can sustain, the heat pipe reaches its maximum heat transfer capacity. In this situation, any attempt to increase the evaporation or condensation rate will cause an insufficient supply of liquid to the evaporation area due to an insufficient capillary pressure. As a result, the amount of the liquid supplied to the evaporation area is lower than the amount of the liquid evaporated therein per unit time, thus leading to the dry-out and overheating of the evaporation area. In a serious case, within a short time, the wall of the heat pipe will be increased to such a high temperature as to cause burnout.
At the same capillary pressure, the wick width (equivalent to the liquid supply diameter) of the heat pipe for liquid transport toward the evaporation area is equal to its cross-sectional inner perimeter that is 12 mm (not with wall thickness), while the minimum wick with of the heat-wing is 110 mm (35 mm×3.14), higher than 900% of that of the heat pipe. Further, the liquid transport occurs in the heat-wing in a manner of converging through a circular space toward the central evaporation area. Therefore, it is nearly impossible for the heat-wing to reach a capillary limit.
5. Condenser limit: The condenser limit refers to the maximum heat transfer rate achievable at the vapor-liquid interface in the condensation area of the heat pipe. The maximum heat transfer capability of the heat pipe may be limited by the condensing capacity of the condensation area which is proportional to the surface area thereof.
Compared to the condensation area surface area of the heat pipe that is 3100 mm²(6 mm×3.14×165 mm), that of the heat-wing is 20000 mm²(100 mm×100 mm×2), 700% of that of the heat pipe.
It can be understood from the foregoing description that particular substantive features of the heat-wing of this invention are a better temperature uniformity in the evaporator and condensation areas, low surface temperature of the heat source, and two orders of magnitude higher heat flux density sustainability, which are realizable under the same operating condition as the heat pipe. In the heat transfer field, this is a great breakthrough comparable to the invention of the first heat pipe. Since the advent of the phase-change heat transfer theory, its primary application has been still being limited to its prototype—heat pipes. The heat-wing disclosed herein is a novel product of the theory which has an unprecedented working mechanism. It will greatly promote the application of the phase-change heat transfer theory.
For example, as the performance of CPUs is proportional to their power consumption, the pursuit for higher CPU performance is always frustrated by the increased heat caused by a proportional rise in the power consumption. This necessitates the employment of heat dissipaters that can sustain a higher heat flux density. Therefore, conventional high-performance computers are all desktop computers equipped with a huge tower case for accommodating a huge heat-pipe heat dissipater, and thus have a very limited transportability. In contrast, if the heat-wing of the present invention is used, as shown in FIGS. 11 and 12, the thickness of the heat dissipater will be greatly reduced to 2-3 cm. This will eliminate the huge tower case and enable the construction of a high-performance computer with the same thickness as current all-in-one computers, or even as relatively thick laptop computers.
Comparison Between Heat-Wing and Conventional Vapor Chamber
It is known to those skilled in the art that the effective thermal conductivity of phase-change heat transfer is 3 orders of magnitude higher than that of solid mediums. Therefore, in the design of phase change heat exchangers, it is essential to minimize the length of the heat conduction medium between the phase change heat exchanger and the heat source.
When using the conventional vapor chamber as shown in FIG. 2, heat is transferred successively through the heat conduction piece 41 and clamps 412 which are arranged in a direction perpendicular to the plane of the heat source and finally reaches the plates of the vapor chambers 42 and 42′. In such a configuration, the distance from the heat source to the vapor chambers is too long, which is a thickness of the heat conduction piece 41 plus half of a height of the clamp, while a total heat conduction width in the clamps 412 is too short, which is only a sum of the widths of the two clamps 412, thereby results in a relatively high thermal resistance. While in the heat-wing of the present invention (e.g. the configuration shown in FIGS. 3 and 4), the frame section 23 is in parallel with the plane of heat source and brought in direct contact with the heat source. Therefore, the distance from the heat source to the phase transition working medium is merely a thickness of the frame section, and the heat conduction width is equal to the width of the heat source. Compared with the conventional vapor chamber, the heat-wing of the present invention has greatly reduced the length of or even eliminated the heat conduction medium between the phase change heat exchanger and the heat source, and hence has greatly lowered the thermal resistance. It is a similar occasion with the configuration shown in FIG. 9 where a portion of a periphery of one plate is brought in direct contact with the heat source, and thereby can achieve the same technical effects.

Claims

What is claimed is:

1. A heat-wing, comprising:

a sealed hollow chamber, including two plates and a frame connecting the two plates;

a capillary structure layer closely attached to an inner surface of the chamber; and

a phase transition working medium sealed in the chamber,

wherein a portion of the frame or a portion of a periphery of one of the two plates as an evaporation area is in direct contact with a heat source, and the rest portion of the chamber as a condensation area is not in contact with the heat source;

wherein each of a length and a width of the chamber is much greater than a thickness of the chamber.

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, further comprising a support or connection structure disposed between the two plates.

4. The heat-wing of claim 3, wherein the support or connection structure assumes a shape of a dot, a line or a sheet.

5. The heat-wing of claim 1, wherein a portion of the frame as an evaporation area is in direct contact with the heat source, and the rest portion of the chamber extends away from the heat source.

6. The heat-wing of claim 1, wherein a portion of the periphery of one of the two plates as an evaporation area is in direct contact with the heat source, and the rest portion of the chamber extends away from the heat source.

7. The heat-wing of claim 1, wherein the two plates are flat or curved.

8. The heat-wing of claim 1, wherein the chamber is fabricated from a material selected from a group consisting of copper, aluminum, stainless steel metal and alloys thereof, high thermal conductivity ceramics, and other high thermal conductivity materials.

9. The heat-wing of claim 1, wherein the capillary structure layer is made of sintered powder(s), wire lattices, grooves, fibers, coated or grown carbon nanowalls, carbon nanotubes or carbon nanocapsules, other coated or grown nano-order or micro-order thin organic or inorganic layer(s) or any combination of the above.

10. The heat-wing of claim 1, wherein the capillary structure layer is a single-layer structure or a multi-layer structure, or any other suitable structure providing capillary attraction.

11. The heat-wing of claim 1, wherein the phase transition working medium is selected from a group consisting of 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.

12. The heat-wing of claim 1, wherein each of the two plates assume a rectangular shape or any other shape.

13. The heat-wing of claim 1, wherein the chamber has a cross-sectional area of a section near to the evaporation area that is larger than, equal to or smaller than a cross-sectional area of an upper section of the chamber.

14. The heat-wing of claim 1, wherein the heat-wing can be evacuated to a certain degree of vacuum.

15. The heat-wing of claim 1, further comprising one or more fins.

16. The heat-wing of claim 15, wherein the chamber and/or the one or more fins is coated with a black-body radiator material.

17. The heat-wing of claim 1, further comprising a hose for vacuuming and liquid filling.