KR20050032888A - Flat plate heat transfer device - Google Patents

Abstract

A plate type heat transfer device is provided to reduce thickness thereof by removing a wick structure and to prevent deformation by solidly supporting a plate type case with a mesh. A thermal conductive plate type case(130) is installed between a heat source(110) and a heat dissipating part(120) and contains a refrigerant evaporated with absorbing heat from the heat source and condensed with dissipating heat from the heat dissipating part. A mesh layer(140) is installed inside the case and is woven to alternately cross wires(140a,140b) up and down. Diffusion passages of vapor refrigerant are formed along by surfaces of the wires from a cross point of the mesh around the heat source. Flow passages of liquid refrigerant due to a capillary phenomenon are formed in a direction from the mesh lattice located around the heat dissipating part to the mesh lattice located around the heat source along by a wire progress direction.

Description

Flat Plate Heat Transfer Device

The present invention relates to a plate heat transfer device capable of transferring heat to a circulation mechanism by evaporation and condensation of a refrigerant without applying additional mechanical energy. A plate heat transfer device having an improved structure that can prevent deformation.

In recent years, electronic devices such as notebook computers and PDAs have become smaller and smaller in thickness due to the development of high integration technology. In addition, as the demand for high responsiveness and function improvement of electronic equipment increases, power consumption is also gradually increasing. Therefore, since a lot of heat is generated from the electronic components therein during the operation of the electronic equipment, various plate heat transfer devices are used to release this heat to the outside.

Representative examples of the conventional plate heat transfer apparatus include a heat pipe sealed after depressurizing a plate metal case in a vacuum state and injecting a refrigerant.

When the heat pipe is installed such that a portion of the heat pipe is in contact with an electronic component (heat source) that generates heat, the refrigerant near the heat source is heated to vaporize and then diffuses into a relatively low temperature region. The vapor then condenses again as it releases heat to the outside, becoming a liquid and returning to its original position. As described above, heat generated from the heat source is released to the outside by the circulation mechanism of the refrigerant inside the plate-shaped metal case, thereby maintaining the temperature of the electronic component at an appropriate line.

FIG. 1 illustrates a conventional plate-shaped heat transfer device 10 installed between the heat source 20 and the heat sink 30 to transfer heat from the heat source 20 to the heat sink 30 in more detail.

Referring to the drawings, the conventional plate heat transfer device 10 is made of a metal case 50 in which a refrigerant is filled in the interior 40. In addition, a wick structure 60 is formed on an inner surface of the metal case 50 to provide an efficient circulation mechanism of the refrigerant.

The heat generated from the heat source 20 is transferred to the wick structure 60 inside the plate heat transfer device 10 in contact with the heat source 20. Then, the refrigerant contained in the wick structure 60 (which functions as a 'coolant evaporator') near the upper portion of the heat source 20 is evaporated and diffused in all directions through the internal space 40, and then the heat sink 30. ) Condenses after dissipating heat from the wick structure 60 (functioning as a 'coolant condensation unit') directly below. The heat released in the condensation process is transferred to the heat sink 30 and released to the outside by forced convection by the fan 70.

In order to implement the heat transfer mechanism as described above in the plate heat transfer device 10, the liquid refrigerant must absorb heat from the refrigerant evaporation unit directly above the heat source 20, evaporate, and then move to the refrigerant condenser. Therefore, the plate heat transfer device 10 should basically have a space in which the vapor of the refrigerant can diffuse into the refrigerant condenser. If a space in which the refrigerant diffuses from the refrigerant evaporator to the refrigerant condenser is not provided, a heat transfer mechanism due to evaporation and condensation of the refrigerant is not properly implemented, which causes a problem of deterioration of the performance of the heat transfer device.

Meanwhile, as the thickness of electronic equipment becomes thinner recently, ultrathin plate heat transfer devices are required. However, in the case of the conventional plate heat transfer apparatus 10, since the inside of the thin metal case 50 is not only maintained in a vacuum state (depressurized state) but also does not employ a mechanical structure that can withstand external shocks, There is a problem in that the heat transfer characteristics of the product are deteriorated by the deformation of the diffusion path of the vapor due to the metal case 50 is crushed even in the minor impact during the handling process. Therefore, the structure of the conventional plate-shaped heat transfer device 10 as described above is limited to accommodate the current ultra-thinning demand.

Therefore, the present invention was devised to solve the above-described problems of the prior art, and the ultra-thinning is possible while maintaining the heat transfer mechanism by evaporation and condensation of the refrigerant, and the impact of the device from the impact that can be applied in the manufacturing or handling process. It is an object of the present invention to provide a plate heat transfer apparatus having an improved internal structure capable of preventing deformation.

The plate-type heat transfer apparatus according to the present invention for achieving the above technical problem, is installed between the heat source and the heat dissipation unit, the thermoelectric containing the refrigerant that is condensed while absorbing heat from the heat source and evaporating heat from the heat dissipation unit Conductive plate-shaped case; And a layer of mesh installed inside the case, the wires being woven so that the wires alternate alternately up and down, wherein the diffusion passage of the vapor phase refrigerant along the surface of the wire is formed from the intersection point of the mesh near the heat source. And a flow passage of the liquid refrigerant due to capillary action along the wire traveling direction from the mesh lattice in the vicinity of the heat dissipation unit to the mesh lattice in the vicinity of the heat source.

Preferably, the mesh is a screen mesh having a mesh number of 10 to 60.

The mesh is preferably woven from a wire having a diameter of 0.12 mm to 0.4 mm.

The height of the thermally conductive plate-shaped case is preferably 0.3mm to 1.0mm.

In the present invention, when the mesh is a screen mesh, it is preferable that the longitudinal wire advancing direction of the mesh coincides with a heat transfer direction.

In the present invention, when the heat conductive plate-shaped case is made of an electrolytic copper foil, it is preferable that the uneven surface of the electrolytic copper foil constitutes an inner surface of the case.

The mesh is made of metal, polymer, plastic or fiberglass. Here, the metal may be copper, aluminum, stainless steel, molybdenum, or an alloy thereof.

The plate case is made of a metal, a conductive polymer, a metal coated with a conductive polymer or a conductive plastic. Here, the metal may be copper, aluminum, stainless steel, molybdenum, or an alloy thereof.

The plate case may be sealed by laser welding, plasma welding, TIG welding, ultrasonic welding, brazing bonding, soldering bonding or thermocompression lamination.

The refrigerant may be water, methanol, ethanol, acetone, ammonia, CFC refrigerant, HCFC refrigerant, HFC refrigerant, or a mixed refrigerant thereof.

Hereinafter, the present invention will be described in detail with reference to examples, and detailed description will be made with reference to the accompanying drawings to help understand the present invention. However, embodiments according to the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more clearly and easily describe the present invention to those skilled in the art. Like reference numerals in the drawings refer to like elements.

Plate heat transfer apparatus 100 according to a preferred embodiment of the present invention, as shown in Figure 2, the plate-shaped case 130 is installed between the heat source 110 and the heat dissipation unit 120, such as a heat sink, One mesh 140 inserted into the case 130 and a refrigerant injected into the case 130 and used as a medium for transferring heat from the heat source 110 to the heat dissipation part 120.

In the plate heat transfer apparatus 100, a refrigerant located directly above the heat source 110 (hereinafter, referred to as a 'coolant evaporator') is evaporated into steam to provide a vapor diffusion passage provided by the mesh 140 ( Diffusion). Then, the vapor phase refrigerant is condensed back into the liquid phase in a place where the temperature is relatively lower than the heat source 110 (hereinafter, referred to as a 'coolant condensation unit'), such as near the bottom of the heat dissipation unit 120. Subsequently, the condensed liquid refrigerant flows back and is directly above the heat source 110 along the liquid flow path (to be described later) formed by the capillary phenomenon caused by the mesh 140. In this process, the refrigerant takes heat from the heat source 110 and transfers heat to the heat dissipation unit 120. And the heat transferred to the heat dissipation unit 120 is discharged to the outside by the forced convection method by the fan 150, so that the temperature of the heat source 110 is maintained at an appropriate line. In an ideal case, the heat transfer mechanism by evaporation and condensation of the refrigerant continues until the temperature of the heat source 110 and the temperature of the heat dissipating part 120 become substantially the same.

The plate-shaped case 130 is in a state in which the inside of the vacuum is reduced in pressure, the material is a metal having excellent thermal conductivity so as to easily absorb heat from the heat source 110 and to release heat back to the heat dissipation unit 120, It consists of a conductive polymer, a metal coated with a conductive polymer or a thermally conductive plastic. Preferably, the metal is any one of copper, aluminum, stainless steel or molybdenum or alloys thereof. In particular, when the plate-shaped case 130 is made of an electrolytic copper foil having irregularities on one side, it is preferable to face the surface with the irregularities toward the inner surface of the plate-shaped case 130. In this case, since the return of the refrigerant due to the capillary phenomenon is made more smoothly, the efficiency of the plate heat transfer apparatus 100 is increased. The plate-shaped case 130 preferably has a thickness of 0.01 mm to 1.0 mm in consideration of thermal conductivity and mechanical strength characteristics.

The mesh 140 is provided between the upper plate and the lower plate of the plate-shaped case 130 and is woven by alternating wires 140a and 140b alternately up and down, and may be made of any one of metal, polymer, glass fiber, or plastic. Can be. Preferably, the metal is any one of copper, aluminum, stainless steel or molybdenum or alloys thereof. The mesh 140 may be manufactured in various shapes corresponding to the shape of the plate-shaped case 130 of the plate-shaped heat transfer device 100.

3 and 4, the mesh 140 is a woven mesh that intersects the lateral wire 140a and the vertical wire 140b so as to alternate with each other. The width a of the empty space existing in the unit grid of the mesh 140 is generally expressed by Equation 1 below.

a = (1-Nd) / N

Here, d is the diameter of the mesh wire (inch), N is the number of grids of the mesh 140 present in the length of 1 inch. For example, if N is 100 in the square mesh 140, 100 mesh grids exist in a length of 1 inch.

In the present invention, the mesh 140 is a means for providing a vapor diffusion passage (I) through which the vapor phase refrigerant evaporated by the heat source 110 can flow. Specifically, as shown in FIG. 4, the mesh 140 has a space 160 formed by the horizontal wire 140a and the vertical wire 140b crossing up and down, and the space 160 diffuses vapor. It can serve as a vapor diffusion flow path (I). Here, the vertical wires 140b refer to mesh wires arranged in rows in the longitudinal direction when the mesh 140 is woven, and the horizontal wires 140a refer to mesh wires arranged in the vertical direction of the vertical wires 140b.

The geometric area A of the vapor diffusion flow path I is calculated as shown in Equation 2 below.

A = (a + d) d - πd 2/4

Referring to Equation 2, the geometric area of the vapor diffusion flow passage I increases as the mesh number N decreases and the diameter d of the mesh wire increases.

Since there are a total of four vapor diffusion flow paths (I) shared with the neighboring grids in the grid of the mesh 140, the diffusion of the vapor phase refrigerant is all around the center O of the mesh grid as shown in FIG. 3. This is done smoothly (see arrow '↔').

When the mesh 140 is a screen mesh, when viewed from the traveling direction of the vertical wire 140b (see FIG. 4), the slope of the horizontal wire 140a is greater than the inclination of the horizontal wire 140a disposed perpendicular to the vertical wire 140b. When viewed in the advancing direction (not shown), the inclination of the vertical wires 140b disposed perpendicular to the horizontal wires 140a is greater. Therefore, since the diffusion of the vapor phase refrigerant is relatively smoother in the direction of the vertical wire 140b of the mesh 140 than in the horizontal wire 140a, the heat transfer efficiency is high. Therefore, when the mesh 140 is a screen mesh, it is preferable to make the heat transfer direction coincide with the traveling direction of the vertical wire 140b when installing and operating the plate heat transfer apparatus 100.

Meanwhile, when the plate heat transfer device 100 according to the present invention is actually operated, the mesh 140 is in contact with the liquid refrigerant in a state in contact with the upper and lower plates of the plate-shaped case 130 as shown in FIG. 5. do. Therefore, the liquid film 180 is formed by the liquid refrigerant in the wedge-shaped gap 170 of the vapor diffusion passage I existing in the mesh 140.

The liquid film 180 is formed at all intersection points of the mesh wires as shown in FIG. If the width (a) of the mesh lattice and / or the diameter (d) of the mesh wire is properly controlled among the parameters of the mesh 140, the liquid film 180 formed at the intersection point of the wires is connected to each other to generate a capillary phenomenon. Therefore, when the refrigerant contained in the liquid film 180 evaporates in the mesh lattice present in the refrigerant evaporation unit, the refrigerant contained in the neighboring mesh lattice as the amount of evaporated refrigerant causes the moving direction of the mesh wire by capillary action. Accordingly, the refrigerant flows to the mesh lattice.

In other words, in the plate heat transfer apparatus 100 according to the present invention, the refrigerant evaporation is continuously evaporated and diffused in the refrigerant evaporation of the liquid refrigerant shortage occurs on the contrary, the refrigerant condensation in the refrigerant condensation of the excess of the liquid refrigerant This will occur. However, due to the capillary phenomenon caused by the surface tension of the liquid film 180 formed in the mesh lattice, the liquid refrigerant flows from the refrigerant condenser to the refrigerant evaporator, and the refrigerant continuously replenishes the refrigerant evaporator along the advancing direction of the mesh wire. As a result, the heat transfer mechanism by evaporation and condensation of the refrigerant is maintained. That is, the flow path of the liquid refrigerant is formed along the advancing direction of the mesh wire.

However, when the mesh number N of the mesh 140 becomes too large or the diameter d of the mesh wire becomes too small, the vapor diffusion passage I is completely blocked by the liquid refrigerant by the surface tension. In this case, the refrigerant evaporated in the refrigerant evaporation unit may not diffuse into the refrigerant condensation unit through the vapor diffusion passage I, and thus heat transfer may not be performed smoothly. Therefore, the parameters of the mesh 140, that is, the mesh number N and the diameter d of the mesh wire, provide the vapor diffusion passage I through the mesh 140 as well as the flow passage of the liquid refrigerant by capillary action. It is desirable to choose appropriately, considering that it must be done. Preferably, the mesh 140 has a mesh number of 10 to 60, the diameter of the mesh wire is used is 0.2mm to 0.4mm.

According to the present invention, since the mesh providing the vapor diffusion passage and the liquid flow passage at the same time is provided, there is no need for a separate wick structure inside the plate-shaped case 130 as in the prior art. Accordingly, the thickness of the plate heat transfer apparatus 100 may be reduced to about 0.3 mm to about 1 mm in correspondence with the omission of the wick structure. In addition, since the mesh 140 included in the plate heat transfer device 100 also serves to support the plate case 130, the mechanical strength of the plate heat transfer device 100 is increased than in the related art.

Plate heat transfer apparatus 100 according to the present invention can be configured in various shapes, such as square, rectangular, T-shaped, as shown in Figures 7 to 9. In addition, the plate-shaped case 130 of the flat heat transfer device 100 may be configured as a separate combination of the upper plate case 130a and the lower plate case 130b as shown in FIGS. 10 and 11, and as shown in FIG. 12. It can also consist of only one case.

Final sealing of the plate-shaped case 130 is performed after the refrigerant is filled in a state where the inside of the plate is decompressed to a vacuum level. The sealing consists of laser welding, plasma welding, TIG welding, ultrasonic welding, brazing bonding, soldering bonding, thermocompression lamination, and the like.

As the refrigerant, water, methanol, ethanol, acetone, ammonia, CFC refrigerant, HCFC refrigerant, HFC refrigerant, or a mixed refrigerant thereof can be employed.

<Experimental example>

Applicant has produced a plate heat transfer device such that the width, length and height are 40 mm, 70 mm and 0.65 mm, respectively, in order to examine the effect of the plate heat transfer device according to the present invention. The plate-shaped case was configured by separately combining the upper plate case and the lower plate case, as shown in Figure 10, the material used was a rolled copper foil having a thickness of 0.1mm. As the mesh to be mounted inside the plate-shaped case, a copper screen mesh having 15 meshes, 0.20 mm diameter of mesh wire, and 99% or more copper content was used.

In order to manufacture a plate heat transfer device to be used in this experiment, first, a screen mesh is placed between the upper case and the lower case, and each case is facing each other as shown in FIG. 10, and then a modified acrylic two-component bond manufactured by Denka Co., Ltd. Brand name is HARDLOC, and the refrigerant inlet was left behind and sealed.

Then, after injecting the refrigerant, the inside of the plate case was reduced to 1.0 × 10 ^-7 torr by using a rotary vacuum pump and a diffusion vacuum pump, and 0.23cc of the refrigerant was filled with distilled water and finally sealed.

A heat source having a width of 12 mm and a length of 12 mm was attached to the center of a 10 mm spaced point from one end of the plate-shaped heat transfer device manufactured as described above. This attached heat sink was attached. At this time, the heat source and the heat sink were attached to the same side of the plate heat transfer device. Then, we started to apply 1W of power to the heat source, and measured the temperature of the heat source surface while increasing the power to 5W.

According to the experimental results, even if the maximum power of 5W is supplied to the heat source, the temperature of the heat source was confirmed that does not exceed 47 ℃. Therefore, it can be seen that the plate-shaped heat transfer device according to the present invention can be employed as a heat transfer device for cooling electronic equipment that has a very thin thickness and relatively low heat generation.

In the above described with reference to the accompanying drawings, preferred embodiments of the present invention in detail. However, embodiments of the present invention may be variously modified or applied by those skilled in the art, the scope of the technical idea according to the present invention should be determined by the claims below. will be.

According to the present invention, the wick structure can be removed by inserting a mesh capable of simultaneously providing the diffusion channel of the vapor refrigerant and the flow channel of the liquid refrigerant into the plate-shaped case, thereby making the plate heat transfer device extremely thin. In addition, since the mesh firmly supports the plate-shaped case, it is possible to prevent the device from being deformed even when an impact is applied during the manufacturing or handling of the plate-type heat transfer device.

The present invention will be described in detail with reference to the following drawings, but these drawings illustrate preferred embodiments of the present invention, and thus the technical spirit of the present invention should not be construed as being limited to the drawings.

1 is a cross sectional view of a conventional plate heat transfer apparatus.

2 is a cross-sectional view of an installation of a plate heat transfer apparatus according to an embodiment of the present invention.

3 is a grid plan view of a woven mesh mounted inside a plate-shaped case of the plate-shaped heat transfer device according to an embodiment of the present invention.

4 is a cross-sectional view taken along the line AA ′ of FIG. 3.

5 and 6 are partial cross sectional and partial plan views of the plate heat transfer apparatus, respectively, showing that a liquid film is formed on the mesh when the plate heat transfer apparatus according to the present invention is operated.

7 to 9 are device perspective views showing various appearances of the plate heat transfer apparatus according to the present invention.

10 to 12 are cross-sectional views showing various configurations of the case of the plate heat transfer apparatus according to the present invention.

Claims (13)

A thermally conductive plate-shaped case installed between the heat source and the heat dissipating unit and containing a refrigerant condensed while absorbing heat from the heat source and dissipating heat from the heat dissipating unit; And And a layer of mesh installed inside the case and woven so that the wires alternate alternately up and down. A diffusion path of vapor phase refrigerant is formed along the surface of the wire from the intersection point of the mesh near the heat source, and the wire traveling direction is moved from the mesh grating near the heat dissipation part to the mesh grating near the heat source. The flow path of the liquid refrigerant by the capillary phenomenon is formed according to the plate-shaped heat transfer device. The method of claim 1, The mesh is a plate-type heat transfer device, characterized in that the screen mesh of 10 to 60 mesh number. The method of claim 1, The mesh is a plate heat transfer device, characterized in that the woven wire with a diameter of 0.12mm to 0.4mm. The method of claim 1, Plate-type heat transfer device, characterized in that the height of the thermally conductive plate-shaped case is 0.3mm to 1.0mm. The method of claim 1, The plate-type case is a plate-type heat transfer device, characterized in that consisting of a combination of the upper and lower case. The method of claim 1, The mesh is a screen mesh, Plate-type heat transfer device, characterized in that the longitudinal wire running direction of the mesh wire coincides with the direction in which heat transfer is made. The method of claim 1, The heat conductive plate-shaped case is made of an electrolytic copper foil, The plate-shaped heat transfer apparatus characterized by the uneven surface of the said electrolytic copper foil comprise the inner surface of the said case. The method according to any one of claims 1 to 7, The mesh is a plate heat transfer device, characterized in that made of metal, polymer, plastic or glass fiber. The method of claim 8, And said metal is copper, aluminum, stainless steel, molybdenum or an alloy thereof. The method according to any one of claims 1 to 7, The plate-shaped case is a plate, heat transfer device, characterized in that made of a metal, a conductive polymer, a metal or conductive plastic coated with a conductive polymer. The method of claim 10, And said metal is copper, aluminum, stainless steel, molybdenum or an alloy thereof. The method according to any one of claims 1 to 7, Sealing of the plate-shaped case is a plate heat transfer device, characterized in that consisting of laser welding, plasma welding, TIG welding, ultrasonic welding, brazing bonding, soldering bonding or thermocompression lamination method. The method according to any one of claims 1 to 7, And the refrigerant is water, methanol, ethanol, acetone, ammonia, CFC refrigerant, HCFC refrigerant, HFC refrigerant or a mixed refrigerant thereof.