Flat plate heat transfer device and method for manufacturing the same
A flat plate heat transfer device contacted with heat source and heat-emitting unit at both end transfers heat generated at the heat source to the heat-emitting unit horizontally. The device includes a thermally-conductive flat case containing a working fluid evaporated with absorbing heat from the heat source and condensed with emitting heat to the heat-emitting unit; and a mesh aggregate installed in the case so that coarse and fine meshes in which wires are woven to be alternately crossed up/down are vertically laminated in contact. The coarse mesh gives main-directional and sub-directional vapor dispersion channels with different sectional areas at each crossing point of the mesh wires for vapor to flow therethrough. The main-directional vapor dispersion channel with relatively larger sectional area is parallel to heat transfer direction. The fine mesh gives liquid flow channels along running direction of the mesh wire from each crossing point of the mesh wires.
The present invention relates to a flat plate heat transfer device capable of emitting heat from a heat source by circulating a working fluid using evaporation and condensation and its manufacturing method, and more particularly to a flat plate heat transfer device capable of preventing crush of a flat case and giving vapor dispersion channels and liquid flow channels in a direction that ensures a maximum heat transfer efficiency and its manufacturing method.
BACKGROUND ARTIn recent, an electronic equipment such as notebook or PDA becomes smaller and thinner along with the development of integration technique. In addition, together with the increased demands for higher responsiveness of an electronic equipment and improvement of functions, energy consumption is also tending increased. Accordingly, much heat is generated from electronic components in the electronic equipment while the equipment is operated, so various flat plate heat transfer devices are used to emit the heat outside.
As a traditional example of the conventional flat plate heat transfer device, a heat pipe is widely known in the art. The heat pipe is configured so that an inside of a sealed container is decompressed in a vacuum so as to be isolated from an ambient air, and then the container is sealed after a working fluid is injected therein. As for its operation, a working fluid is heated and evaporated near the heat source to which the heat pipe is installed, and then flowed to a cooling part. At the cooling part, the vapor is condensed into a liquid again with emitting heat outside, and then returns to its original position. By means of such working fluid circulating mechanism, the heat generated in the heat source is emitted outside, so the temperature of the electronic component may be kept in a suitable level accordingly.
U.S. Pat. No. 5,642,775 issued to Akachi et al. discloses a plate heat pipe including a plate with minute channels called capillary tunnel and formed by an extrusion method, and a working fluid filled therein. If one end of the plate is heated, the working fluid is heated and evaporated into a vapor and then moved to the other end of each channel, and then cooled and condensed again and moved to a heating part. The plate heat pipe of Akachi et al. may be adopted between a motherboard and a printed circuit card. However, forming a plurality of such small and fine capillary channels by means of extrusion is very difficult.
U.S. Pat. No. 5,309,986 issued to Itoh discloses an air-sealed rectangular container and a heat carrier (working fluid) filled in the container. In the patent, an inclined groove is formed on an inner surface of the container, and the container has pointed corners so that a condensed working fluid may be evenly distributed in the entire region of the container, which accordingly enables to effectively absorb and emit heat.
U.S. Pat. No. 6,148,906 issued to Li et al. discloses a flat plate heat pipe for delivering heat from a heat source positioned in an electronic equipment enclosure to an external heatsink. The flat plate heat pipe includes a metallic bottom plate having a depression therein containing a set of rods and a top plate for covering the bottom plate. The space restricted by the bottom plate, the top plate and the rods is decompressed and filled with a working fluid. As mentioned above, the working fluid absorbs heat from a heating part in the channel and then moves to a cooling part, and the working fluid condensed with emitting heat in the cooling part is circulated again to the heating part so that the equipment is cooled.
Such cooling devices should have a sufficient space for the vapor to flow since the working fluid in a liquid state should be evaporated with absorbing heat from the heat source and the evaporated vapor should be moved again to the cooling region. However, it is not easy to have a sufficient vapor dispersion channel in the flat case of the flat plate heat transfer device with small thickness. In particular, since the flat case is kept in a vacuous state (or, a decompressed state), the upper and lower plates of the case are apt to be crushed or distorted during its manufacturing procedure, thereby deteriorating reliability of the product.
DISCLOSURE OF INVENTIONThe present invention is designed to solve the problems of the prior art, and therefore it is an object of the present invention to provide an improved flat plate heat transfer device with a geometric structure that is capable of preventing distortion of the device to ensure reliability of product by firmly supporting a flat case of the flat plate heat transfer device that becomes thinner, and also giving a vapor dispersion channel and a liquid flow channel in an optimized direction for effective heat transfer.
In order to accomplish the above object, the present invention provides a flat plate heat transfer device, one end of which is contacted with a heat source and the other end of which is contacted with a heat emitting unit, the device transferring heat generated at the heat source to the heat emitting unit in a horizontal direction, the device including a thermally-conductive flat case containing a working fluid that is evaporated with absorbing heat from the heat source and condensed with emitting heat to the heat emitting unit; and a mesh aggregate installed in the case and configured so that coarse mesh and fine mesh in which wires are woven to be alternately crossed up and down are vertically laminated with being contacted with each other, wherein the coarse mesh provides main-directional and sub-directional vapor dispersion channels with different sectional areas at each crossing point of mesh wires so that vapor evaporated from the working fluid is capable of flowing therethrough, the main-directional vapor dispersion channel with a relatively larger sectional area being parallel to a heat transfer direction, wherein the fine mesh provides liquid flow channels along a surface of the mesh wires.
Preferably, an opening width [M=(1−Nd)/N, where N is a mesh number, and d is a wire diameter (inch)] of the coarse mesh is 0.19 to 2.0 mm, the coarse mesh has a wire diameter of 0.17 to 0.5 mm, and the coarse mesh has an opening area of 0.036 to 4.0 mm2. The coarse mesh also preferably has a mesh number from 10 to 60 on the basis of ASTM specification E-11-95.
Preferably, an opening width [M=(1−Nd)/N, where N is a mesh number, and d is a wire diameter (inch)] of the fine mesh is 0.019 to 0.18 mm, the fine mesh has a wire diameter of 0.02 to 0.16 mm, and the fine mesh has an opening area of 0.00036 to 0.0324 mm2. The fine mesh also preferably has a mesh number from 80 to 400 on the basis of ASTM specification E-11-95.
Preferably, the fine mesh is arranged adjacent to the heat source and the coarse mesh is arranged adjacent to the heat emitting unit.
In one aspect of the invention, the mesh aggregate is configured so that the coarse mesh is interposed between two layers of fine meshes. At this time, at least one layer of additional fine mesh may be further provided in at least a part of the coarse mesh interposed between the fine meshes so as to give a liquid channel by interconnecting the fine meshes.
In another aspect of the invention, the mesh aggregate is configured so that the fine mesh, the coarse mesh and an intermediate mesh are subsequently laminated from bottom to top. Here, the intermediate mesh has a mesh number relatively larger than that of the coarse mesh and relatively smaller than that of the fine mesh. At this time, at least one layer of additional fine or intermediate mesh may be further provided in at least a part of the coarse mesh interposed between the fine mesh and the intermediate mesh so as to give a channel by interconnecting the fine mesh and the intermediate mesh.
In still another aspect of the invention, the mesh aggregate is configured to include the fine mesh as a lower layer and the coarse mesh and the intermediate mesh as an upper layer so that the intermediate mesh is faced with the heat emitting unit. At this time, the intermediate mesh may have a vapor flow space so that the vapor introduced from the coarse mesh flows therein.
According to the present invention, the flat plate heat transfer device may further include a wick structure installed in contact with the mesh aggregate and located under the mesh aggregate within the case, the wick structure having unevenness on a surface so that the working fluid is contained and flowed therein and at the same time evaporated by means of heat absorbed from the heat source and flowed toward the mesh aggregate.
The wick structure may be formed by sintered copper, stainless steel, or nickel powder, or by etching polymer, silicon, silica, copper, stainless steel, nickel, or aluminum plate. As an alternative, the case may be made of electrolytic copper foil so that an inner surface having prominence and depression is used as the wick structure.
According to the present invention, the fine mesh and the intermediate mesh respectively have main-directional and sub-directional liquid flow channels with different sectional areas, and the main-directional liquid flow channel is preferably parallel to a heat transfer direction.
According to the present invention, the working fluid is water, ethanol, ammonia, methanol, nitrogen, or Freon. An amount of filled working fluid is preferably 80 to 150% of wick porosity.
According to the present invention, the mesh is preferably made of metal, polymer, or plastic. Here, the metal includes copper, aluminum, stainless steel, molybdenum, or their alloy.
In addition, the case is made of metal, polymer, or plastic, and the metal preferably includes copper, aluminum, stainless steel, molybdenum, or their alloy.
In order to achieve the above object, there is also provided a method for manufacturing a flat plate heat transfer device. At first, upper and lower plates of the flat case are formed, respectively. And then, a mesh aggregate with a structure that coarse mesh, in which wires are woven to be alternately crossed up and down, and fine mesh, in which wires are woven to be alternately crossed up and down, are laminated vertically is inserted into the flat case. Here, the coarse mesh mainly gives vapor dispersion channels, and the fine mesh layer mainly gives liquid flow channels. The coarse mesh has main-directional and sub-directional vapor dispersion channels with different sectional areas at each crossing point of mesh wires so that vapor evaporated from the working fluid is capable of flowing therethrough, and when the mesh aggregate is inserted into the flat case, it is important to adjust a direction of the coarse mesh so that the main-directional vapor dispersion channels of the coarse mesh are parallel to a heat transfer direction. Subsequently, a flat case is formed by uniting the upper and lower plates with leaving a working fluid injection hole. And then, an inside of the united case is decompressed into a vacuum through the working fluid injection hole and then a working fluid is injected through the working fluid injection hole. Finally, the flat case with the working fluid injected therein is sealed to complete the flat plate heat transfer device.
BRIEF DESCRIPTION OF THE DRAWINGSOther objects and aspects of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawing in which:
FIGS. 11 to 13 are perspective views showing various appearances of the flat plate heat transfer device according to the present invention;
FIGS. 14 to 16 are sectional views showing various examples of a flat case used in the flat plate heat transfer device according to the present invention;
Hereinafter, embodiments are described for specifying the present invention, and detailed description will be provided with reference to the accompanying drawings for better understanding of the invention. However, the embodiments of the present invention may be modified in various ways, and it should not be interpreted that the scope of the invention is limited to the embodiments described below. The embodiments of the invention are provided just for clearer and more definite illustration to those having ordinary skill in the art. In the drawings, the same reference numeral designates the same element.
The flat case 130 is made of metal with excellent thermal conductivity, conductive polymer, or thermal-conductive plastic so that it may easily absorb heat from the heat source 110 and easily emit heat to the heat emitting unit 120.
Meanwhile, the mesh aggregate G of the present invention may be configured as shown in
Referring to
Equation 1
M=(1−Nd)/N
Here, d is a diameter (inch) of the mesh wire, and N is a mesh number (the number of lattices existing in a length of 1 inch.
In the present invention, the coarse mesh 150 acts as a means for giving a vapor dispersion channel through which an evaporated working fluid may flow. More specifically, referring to
Furthermore, as shown in
A maximum sectional area A of the vapor dispersion channel Pv is calculated as follows.
Equation 2
A=(M+d)d−πd2/4
As understood from the equations 1 and 2, the maximum sectional area A of the vapor dispersion channel is increased as the mesh number N is decreased and the diameter d of the mesh wire is increased.
However, the maximum sectional area A is different when it is seen in a running direction Y of the widthwise wires 150a and 150b and when it is seen in a running direction X of the lengthwise wires 150c and 150d. It is because tension is changed according to the direction of meshes since the woven screen mesh is woven by fixing the widthwise wires 150a and 150b or the lengthwise wires 150c and 150d firstly and then weaving the other wires thereto like weaving fabrics.
If the coarse mesh 150 shown in
More specifically, the vapor dispersion channel Pv seen in X direction is shown in
Considering this fact, when configuring the mesh aggregate G as shown in
Meanwhile, as shown in
If the mesh number N of the coarse mesh 150 is very large and the wire diameter d is very small, the maximum sectional area A of the vapor dispersion channel Pv is significantly decreased to increase flow resistance, and the vapor dispersion channel Pv is blocked by liquid due to surface tension, thereby not allowing vapor to flow therethrough. According to experiments carried out by the inventors, in case of a screen mesh conforming to ASTM specification E-11-95, it may be adopted as a coarse mesh 150 if the mesh number N is in the range of 10 to 60. At this time, if a diameter d of the mesh wire is 0.17 mm or more, there is no difficulty for vapor to flow through the vapor dispersion channel Pv.
According to experiments carried out by the inventors, it is preferred that a wire diameter d of the coarse mesh 150 is 0.17 to 0.5 mm, an opening width M of the mesh is 0.19 to 2.0 mm, and an opening area of the mesh is 0.036 to 4.0 mm2.
In addition, as shown in
Though not shown in the figures, a liquid membrane is also formed at crossing points of the widthwise wires and the lengthwise wires of the fine mesh 140. In addition, since the fine mesh 140 mainly gives a liquid flow channel as explained later while the heat transfer device is operating, the empty space of the lattice might be fully filled with the liquid membrane.
The connection of the liquid membranes 170 is enabled by control of the width N of the mesh lattice and/or the diameter d of the mesh wire among parameters of the coarse mesh 150, and it also causes horizontal flow of the working fluid by means of capillary force as mentioned below. Thus, though dispersion of the evaporated working fluid is chiefly induced in the coarse mesh 150 through the vapor dispersion channel Pv, horizontal flow of the liquid is also induced therein by means of the capillary force caused in the interconnected liquid membranes 170. At this time, a direction of the horizontal flow is on average opposite to a heat transfer direction. In addition, an amount of the horizontal flow in the coarse mesh 150 is relatively smaller than an amount of horizontal flow of liquid caused through the fine mesh 140.
Referring to
However, evaporation of the working fluid induced in the region of the fine mesh 140 near the heat source 110 causes deficiency of working fluid, while the working fluid is superfluous in the region of the fine mesh 140 approximately right below the heat emitting unit 120 by means of condensation of the working fluid. Accordingly, capillary force is induced at the interconnected liquid membranes existing in the fine mesh 140, thereby causing continuous flow of the liquid in a direction opposite to a heat transfer direction. That is to say, the fine mesh 140 gives the liquid flow channel so that the working fluid condensed at the region below the heat emitting unit 120 is supplied to the heat source 110. In case of the fine mesh 140, a size of the math lattice is small, so empty spaces of the mesh lattice are filled with liquid by means of the surface tension of the contained working fluid. Accordingly, the fine mesh 140 acts as a liquid flow channel rather than a vapor dispersion channel.
The liquid flow channel of the fine mesh 140 has different maximum sectional areas depending on its direction due to the same reason as the coarse mesh 150. Thus, the fine mesh 140 also has ‘a main direction’ in which a flow rate of the liquid is larger and ‘a sub-direction’ in which a flow rate of liquid is relatively smaller than in the main direction, under the same pressure condition. In the present invention, in order to maximize the heat transfer performance of the flat plate heat transfer device, the mesh aggregate G is preferably configured so that the main direction of the fine mesh 140 is parallel with the heat transfer direction. In this configuration, both the vapor dispersion efficiency of the coarse mesh 150 and the liquid flow efficiency of the fine mesh 140 are optimized, thereby further improving the heat transfer performance of the flat plate heat transfer device.
Considering the function of the fine mesh 140, in case that a screen mesh conforming to ASTM specification E-11-95 is adopted as a fine mesh 140, it is preferred that the mesh number N is in the range of 80 to 400. According to experiments carried out by the inventors, it is preferred that a wire diameter d of the fine mesh 140 is 0.02 to 0.16 mm, an opening width M of the mesh is 0.019 to 0.18 mm, and an opening area of the mesh is 0.00036 to 0.0324 mm2.
In the present invention, a wick structure may be provided to an inner side of the flat case in order to help receiving, condensation and rapid flow of the liquid. Preferably, the wick structure may be made by sintered copper, stainless steel, aluminum or nickel powder. As another example, the wick structure may be made by etching polymer, silicon, silica (SiO2), copper, stainless steel, nickel or aluminum plate.
As an alternative, the flat case may be configured with an electrolytic copper foil that has a rough wick structure with small prominences and depressions about 10 μm on one side but has a smooth surface on the other side. In this case, the surface having a rough wick structure is used as the inner surface of the flat case.
Furthermore, it should be understood that various wick structures made using the miromatching method disclosed in U.S. Pat. No. 6,056,044 issued to Benson, et al may be also adopted as the wick structure of the flat case of the present invention.
The flat plate heat transfer device according to the present invention is manufactured to have a thickness of 0.5 to 2.0 mm, or more than 2.0 mm if necessary. In addition, the flat plate heat transfer device may have various shapes such as square, rectangle, T-shape or the like as shown in FIGS. 11 to 13. In addition, the flat case 130 of the flat plate heat transfer device may be configured with an upper case 130a and a lower case 130b that are separately provided and then assembled as shown in
Preferably, the upper and lower plates 130a and 130b of the flat case 130 may be made of metal, polymer, plastic or the like with a thickness of 0.5 mm or less. The metal may be copper, aluminum, stainless steel, or molybdenum. The polymer may use a polymer material with excellent thermal conductivity like a thermal-conductive polymer. The plastic may also adopt a plastic with excellent thermal conductivity. The flat case 130 may be made by preparing the upper and lower plates 130a and 130b by cutting any of the aforementioned materials into a desired shape and then uniting them using various manners such as brazing, TIG (Tungsten Inert Gas) welding, soldering, laser welding, electron beam welding, friction welding, and bonding. The united flat case is decompressed to a vacuum or a low pressure and then filled with working fluid such as water, ethanol, ammonia, methanol, nitrogen or Freon, and then sealed. Preferably, an amount of working fluid filled in the flat case 130 is set in the range of 80 to 150% of wick porosity.
Now, operation of the flat plate heat transfer device according to a preferred embodiment of the present invention is described with reference to
As shown in
The dispersed vapor is condensed in the fine mesh 140 and the coarse mesh 150 substantially right below the heat emitting unit 120. The condensation heat generated in this condensation process is delivered to the upper plate 130a of the flat case 130, and then subsequently emitted outward by means of conduction, natural convection, or forced convection by, for example, a cooling fan.
The working fluid in a condensed liquid state is contained in the fine mesh 140 and the coarse mesh 150, and then flowed near to the heat source 110 by means of the capillary force caused in the liquid membranes interconnected by continuous evaporation of the working fluid near the heat source 110 so as to be returned to its original position. At this time, the liquid is mainly flowed through the fine mesh 140. The condensed working fluid contained in the coarse mesh 150 is mainly flowed vertically through the crossing points J of the coarse mesh 150 shown in
In a preferred embodiment, since the main direction of the fine mesh 140 is parallel to the heat transfer direction like the coarse mesh 150, the flow of liquid is also optimized, thereby supplying the condensed working fluid to a position near the heat source 110 rapidly.
As already known in the above description, the fine mesh 140 plays a role of an evaporation part at a position right above the heat source 110, a role of a condensation part at a position right below the heat emitting unit 120, and a role of an optimized liquid flow channel by means of a capillary force caused in the interconnected liquid membranes as a whole.
In addition, the coarse mesh 150 plays not only a role of an optimized vapor dispersion channel, but also a role of a condensation part at a position right below the heat emitting unit 120 and a role of a returning path so that the liquid condensed at a position right below the heat emitting unit 120 may be flowed vertically to the fine mesh 140 below the coarse mesh 150 and then returned to its original position. In particular, since the coarse mesh 150 plays a role of a vapor dispersion channel, there is no need to form an empty space in the flat case 130 so as to provide a separate vapor dispersion channel.
In the present invention, the mesh aggregate G supports the upper and lower plates 130a and 130b with being interposed between them, so the upper and lower plates 130a and 130b are not crushed while a vacuum is formed for filling of the working fluid or while the device is handled.
According to the present invention, the mesh aggregate G shown in
A flat plate heat transfer device according to another embodiment of the present invention is shown in
For example, in case that the lower plate 130b is contacted with the heat source 110 and the heat emitting unit 120 is provided to the upper plate 130a, the vapor evaporated from the lower fine mesh layer 140L contacted with the lower plate 130b is dispersed in all directions through the vapor dispersion channels of the coarse mesh layer 150 and then preferably condensed into a liquid with emitting heat at the upper fine mesh layer 140H contacted with the upper plate 130a. Since the fine mesh layer 140H or 140L has a relatively larger mesh number N than the coarse mesh layer 150, the number of condensation points where the vapor may be condensed is accordingly increased, thereby improving the heat emitting efficiency. In addition, the coarse mesh layer 150 gives a returning channel so that the working fluid condensed at the upper fine mesh layer 140H may flow to the lower fine mesh layer 140L.
Preferably, the main directions of the coarse mesh layer 150 and the fine mesh layers 140H and 140L are arranged to be parallel with the heat transfer direction, thereby optimizing vapor dispersion and liquid flow.
Preferably, the main directions of the coarse mesh layer 150 and the fine mesh layers 140H, 140M and 140L are arranged to be parallel with the heat transfer direction, thereby optimizing vapor dispersion and liquid flow.
According to the present invention, it is also possible that different kinds of mesh layers that have at least three kinds of different mesh numbers are provided in complex, as shown in
Preferably, the main directions of the coarse mesh layer 150, the fine mesh layer 140 and the intermediate mesh layer 140′ are arranged to be parallel with the heat transfer direction, thereby optimizing vapor dispersion and liquid flow.
Furthermore, as shown in
FIGS. 21 to 23 show a flat plate heat transfer devices according to still another embodiment of the present invention.
Referring to FIGS. 21 to 23, a fine mesh layer 140 is provided in the flat case 130 at a position adjacent to the heat source 110, and an intermediate mesh layer 140′ is provided therein near the heat emitting unit 120 where a working fluid is condensed with emitting heat. In addition, the fine mesh layer 140 and the intermediate mesh layer 140′ are interconnected by means of a coarse mesh layer 150. Here, the fine mesh layer 140 acts as an evaporation part of the working fluid, the coarse mesh layer 150 acts as a flow channel of vapor, and the intermediate mesh layer 140′ acts as a condensation part of the working fluid. Thus, the working fluid is evaporated by means of the heat delivered from the heat source 110 to the fine mesh layer 140, and the vapor is flowed to the intermediate mesh layer 140′ though the vapor dispersion channel of the coarse mesh layer 140. Subsequently, the vapor is condensed at the intermediate mesh layer 140′ with emitting heat to the heat emitting unit 120. The condensed working fluid in a liquid state is returned again to the evaporation part through the fine mesh layer 140 by means of capillary force.
Preferably, the main directions of the coarse mesh layer 150, the fine mesh layer 140 and the intermediate mesh layer 140′ are arranged to be parallel with the heat transfer direction, thereby optimizing vapor dispersion and liquid flow.
According to this embodiment, in order to promote condensation heat transfer and prevent the vapor dispersion channels from being blocked by formation of liquid membranes, vapor flow spaces 200 (see
As an alternative, the intermediate mesh layer 140′ may be replaced with the fine mesh layer 140. In this case, vapor flow spaces identical to the intermediate mesh layer 140′ may also be formed in the fine mesh layer 140. Furthermore, the vapor flow space is not limited to this embodiment, but it may be suitably designed in the flat case to communicate with the coarse mesh so that the vapor passing through the vapor dispersion channels of the coarse mesh may be guided to the vapor condensation part of the fine mesh layer 140 right below the heat emitting unit 120.
EXPERIMENTAL EXAMPLE Inventors prepared upper and lower plates of a flat case as shown in
The samples 1, 2 and 3 were respectively 120 mm, 50 mm and 1.3 mm in width, length and height, and the mesh used is a copper screen mesh in which a content of copper is at least 99%. The coarse mesh had a wire diameter d of 0.225 mm, a mesh thickness of 0.41 mm and a mesh number of 15, while the fine mesh layer had a wire diameter d of 0.11 mm, a thickness of 0.22 mm and a mesh number of 100. The upper and lower plates of the flat case were sealed by means of denatured acrylic binary bond (HARDLOCTH, made by DENKA in Japan) with leaving a working fluid injection hole. Before the working fluid is injected, the inside of the flat case was decompressed to 1.0×10−7 torr with the use of a rotary vacuum pump and a diffusion vacuum pump, and then the flat case was filled with distilled water as a working fluid, and then finally sealed.
After the samples 1 to 3 were prepared as mentioned above, a copper heat source with width and length of 12 mm respectively was attached to a left portion of the lower plate of the flat case of each sample and a heatsink was installed to a right portion of the upper plate of the flat case of each sample as shown in
Equation 3
Total Thermal Resistance=(Tmeasured temperature−Tambient temperature)/(Qinput power)
Referring to
According to the present invention, it is possible to manufacture a flat plate heat transfer device with a thin thickness, and various shapes. In particular, the method of the present invention does not require MEMS process or etching process that need a lot of costs, and it is possible to provide a flat plate heat transfer device at low costs with the use of inexpensive mesh and case. Furthermore, since the mesh provided in the cooling device prevents the case from being distorted or crushed during the vacuum-forming process or after the device is manufactured, the device may have improved reliability. In addition, since the vapor dispersion channels and the liquid flow channels are optimized for effective heat transfer, the flat plate heat transfer device of the present invention shows high heat transfer performance. The flat plate heat transfer device of the present invention may be efficiently used to cool various electronic equipments such as a mobile electronic terminal.
Claims
1. A flat plate heat transfer device, one end of which is contacted with: a heat source and the other end of which is contacted with a heat emitting unit, the device transferring heat generated at the heat source to the heat emitting unit in a horizontal direction, the device comprising:
- a thermally-conductive flat case containing a working fluid that is evaporated with absorbing heat from the heat source and condensed with emitting heat to the heat emitting unit; and
- a mesh aggregate installed in the case and configured so that coarse mesh and fine mesh in which wires are woven to be alternately crossed up and down are vertically laminated with being contacted with each other,
- wherein the coarse mesh provides main-directional and sub-directional vapor dispersion channels with different sectional areas at each crossing point of mesh wires so that vapor evaporated from the working fluid is capable of flowing therethrough, the main-directional vapor dispersion channel with a relatively larger sectional area being parallel to a heat transfer direction,
- wherein the fine mesh provides liquid flow channels along a surface of the mesh wires.
2. The flat plate heat transfer device according to claim 1,
- wherein an opening width [M=(1−Nd)/N, where N is a mesh number, and d is a wire diameter (inch)] of the coarse mesh is 0.19 to 2.0 mm.
3. The flat plate heat transfer device according to claim 1, wherein the coarse mesh has a wire diameter of 0.17 to 0.5 mm.
4. The flat plate heat transfer device according to claim 1, wherein the coarse mesh has an opening area of 0.036 to 4.0 mm2.
5. The flat plate heat transfer device according to claim 1, wherein the coarse mesh has a mesh number from 10 to 60 on the basis of ASTM specification E-11-95.
6. The flat plate heat transfer device according to claim 1,
- wherein an opening width [M=(1−Nd)/N, where N is a mesh number, and d is a wire diameter (inch)] of the fine mesh is 0.019 to 0.18 mm.
7. The flat plate heat transfer device according to claim 1, wherein the fine mesh has a wire diameter of 0.02 to 0.16 mm.
8. The flat plate heat transfer device according to claim 1, wherein the fine mesh has an opening area of 0.00036 to 0.0324 mm2.
9. The flat plate heat transfer device according to claim 1, wherein the fine mesh has a mesh number from 80 to 400 on the basis of ASTM specification E-11-95.
10. The flat plate heat transfer device according to claim 1,
- wherein the mesh aggregate is configured to include the fine mesh arranged adjacent to the heat source and the coarse mesh laminated thereon adjacent to the heat emitting unit, from bottom to top.
11. The flat plate heat transfer device according to claim 1,
- wherein the mesh aggregate is configured so that the coarse mesh is interposed between two layers of fine meshes.
12. The flat plate heat transfer device according to claim 11,
- wherein at least one layer of additional fine mesh is provided in at least a part of the coarse mesh interposed between the fine meshes so as to give a liquid channel by interconnecting the fine meshes.
13. The flat plate heat transfer device according to claim 1,
- wherein the mesh aggregate further includes at least one layer of intermediate mesh whose mesh number is relatively larger than that of the coarse mesh and relatively smaller than that of the fine mesh.
14. The flat plate heat transfer device according to claim 13,
- wherein the coarse mesh is laminated between the fine mesh and the intermediate mesh.
15. The flat plate heat transfer device according to claim 14,
- wherein at least one layer of additional fine mesh is provided in at least a part of the coarse mesh interposed between the fine mesh and the intermediate mesh so as to give a channel by interconnecting the fine mesh and the intermediate mesh.
16. The flat plate heat transfer device according to claim 14,
- wherein at least one layer of additional intermediate mesh is provided in at least a part of the coarse mesh interposed between the fine mesh and the intermediate mesh so as to give a channel by interconnecting the fine mesh and the intermediate mesh.
17. The flat plate heat transfer device according to claim 14,
- wherein the fine mesh is arranged adjacent to the heat source, and the intermediate mesh is arranged adjacent to the heat emitting unit.
18. The flat plate heat transfer device according to claim 14,
- wherein the fine mesh is arranged adjacent to the heat source so that the working fluid is evaporated into a vapor by means of heat absorbed from the heat source,
- wherein the coarse mesh is arranged in contact with the fine mesh so as to give a channel for the vapor to flow,
- wherein the intermediate mesh is arranged in contact with the coarse mesh and adjacent to the heat emitting unit so that the vapor is condensed with emitting heat to the heat emitting unit.
19. The flat plate heat transfer device according to claim 18,
- wherein the intermediate mesh has a vapor flow space so that the vapor introduced from the coarse mesh flows therein.
20. The flat plate heat transfer device according to claim 1, further comprising:
- a wick structure installed in contact with the mesh aggregate and located under the mesh aggregate within the case, the wick structure having unevenness on a surface so that the working fluid is contained and flowed therein and at the same time evaporated by means of heat absorbed from the heat source and flowed toward the mesh aggregate.
21. The flat plate heat transfer device according to claim 20,
- wherein the wick structure is formed by sintered copper, stainless steel, or nickel powder.
22. The flat plate heat transfer device according to claim 20,
- wherein the wick structure is formed by etching polymer, silicon, silica, copper, stainless steel, nickel, or aluminum plate.
23. The flat plate heat transfer device according to claim 1,
- wherein the case is made of electrolytic copper foil so that an inner surface having prominence and depression is used as the wick structure.
24. The flat plate heat transfer device according to claim 1, wherein the mesh is made of metal, polymer, or plastic.
25. The flat plate heat transfer device according to claim 24, wherein the metal is copper, aluminum, stainless steel, molybdenum, or their alloy.
26. The flat plate heat transfer device according to claim 1, wherein the case is made of metal, polymer, or plastic.
27. The flat plate heat transfer device according to claim 26, wherein the metal is copper, aluminum, stainless steel, molybdenum, or their alloy.
28. The flat plate heat transfer device according to claim 1, wherein the working fluid is water, ethanol, ammonia, methanol, nitrogen, or Freon.
29. The flat plate heat transfer device according to claim 28, wherein an amount of filled working fluid is 80 to 150% of wick porosity.
30. The flat plate heat transfer device according to claim 1,
- wherein the fine mesh has main-directional and sub-directional liquid flow channels with different sectional areas,
- wherein the main-directional liquid flow channel is parallel to a heat transfer direction.
31. The flat plate heat transfer device according to claim 13,
- wherein the intermediate mesh has main-directional and sub-directional liquid flow channels with different sectional areas,
- wherein the main-directional liquid flow channel is parallel to a heat transfer direction.
32. A method for manufacturing a flat plate heat transfer device, which includes a thermal-conductive flat case and a mesh aggregate mounted in the flat case, and which transfers heat in a horizontal direction with the use of a circulating mechanism of a working fluid by means of the mesh aggregate, the method comprising:
- (a) forming upper and lower plates of the flat case, respectively;
- (b) preparing a mesh aggregate with a structure that coarse mesh, in which wires are woven to be alternately crossed up and down, for giving vapor dispersion channels and fine mesh, in which wires are woven to be alternately crossed up and down, for giving liquid flow channels are laminated to be vertically opposite to each other, the coarse mesh having main-directional and sub-directional vapor dispersion channels with different sectional areas at each crossing point of mesh wires so that vapor evaporated from the working fluid is capable of flowing therethrough;
- (c) inserting the mesh aggregate between the upper and lower plates, and adjusting a direction of the mesh aggregate so that the main-directional vapor dispersion channels of the coarse mesh are parallel to a heat transfer direction;
- (d) forming a flat case by uniting the upper and lower plates with leaving a working fluid injection hole;
- (e) decompressing an inside of the united case into a vacuum through the working fluid injection hole and then injecting a working fluid therethrough; and
- (f) sealing the flat case with the working fluid injected therein.
33. The method for manufacturing a flat plate heat transfer device according to claim 32,
- wherein, in the step (b), the fine mesh is selected to have main-directional and sub-directional liquid flow channels with different sectional areas at each crossing point of mesh wires so that vapor evaporated from the working fluid is capable of flowing therethrough, and the mesh aggregate is prepared so that the main-directional liquid flow channels of the fine mesh are parallel to the main-directional vapor dispersion channels of the coarse mesh.
Type: Application
Filed: Dec 14, 2004
Publication Date: Jul 19, 2007
Inventors: Hyun-Tae Kim (Seoul), Yong-Duck Lee (Euiwang-si), Min-Jung Oh (Anyang-si), Sung-Wook Jang (Seoul)
Application Number: 10/583,514
International Classification: F28D 15/00 (20060101);