KR20100033874A - Evaporator for looped heat pipe system - Google Patents

Abstract

PURPOSE: An evaporator for a looped heat pipe system is provided to easily obtain a complex shape of an electro-thermal pin and a wick, and to improve contacting state of the electro-thermal pin and the wick. CONSTITUTION: An evaporator for a looped heat pipe system(1) comprise a porous wick(10) including multiple pores, an electro-thermal pin(20) including a wick combination unit to be combined with the wick, a unit combination, a combination structure(40), a heating plate(50), and a cover members(60). The unit combination is formed with the wick and the electro-thermal pin, and arranged in plural in the horizontal direction in which the lower sides of the unit combinations are located in one surface to form the combination structure. The heating plate is combined to the lower side of the combination structure. The cover member is coupled with the heating plate.

Description

Evaporator for looped heat pipe system

The present invention relates to an evaporator which forms a loop heat pipe system together with a condenser, a gas transfer pipe, and a liquid transfer pipe. In particular, a heat transfer fin coupled to a wick is formed as a separate member, and they are coupled to the heat transfer plate in the wing direction. Therefore, it is not only possible to configure the wick and the heating fins to have various shapes and sizes, but also to an evaporator for a loop type heat pipe system capable of minimizing mutual contact thermal resistance.

Electronic components such as CPUs and semiconductor chips used in various electronic devices such as computers generate a lot of heat during operation. Since such electronic components are usually designed to function properly at room temperature, it is necessary to effectively cool the heat generated during operation.

Several attempts have been made to cool electronic components, one of which is the phase change heat transport system. A recent example of such a phase change heat transfer system is a looped heat pipe (LHP) system.

1 conceptually illustrates a conventional looped heatpipe system 110. The loop heat pipe system 110 includes a condenser 112, an evaporator 114, and a vapor line 116 and a liquid line 118 connecting them. A working fluid is injected into the loop heat pipe system. The loop type heat pipe system 110 is provided with a porous wick only inside the evaporator 114, unlike a heat pipe having a normal cylindrical shape.

The basic principle of the operation of the loop heat pipe system 110 is as follows.

First, an evaporator in contact with an electronic component (not shown) that is a heat source is heated. When the evaporator 114 is heated, the working fluid that has permeated the internal wick phase changes into gas.

At this time, the generated gas is moved to the condenser 112 along the steam line 116 connected to one side of the evaporator 114. The migrated gas then releases heat and liquefies as it passes through the condenser 112. The liquefied working fluid is moved back to the evaporator 114 along the liquid line 118 on one side of the condenser 112. This process is repeated in cycles to cool the electronic components that are heat sources.

On the other hand, total heat resistance must be lowered for high performance and miniaturization of the loop type heat pipe system. When the heat resistance decreases, the heat source, that is, the electronic component, can be operated at a low temperature. In order to reduce the total heat resistance of the system, several factors must be taken into account, but the most direct effect is due to the thermal contact resistance of the evaporator.

Thermal contact resistance shall not consider only the size of the apparent area of the contact surface of two objects where heat transfer occurs. That is, even though the physical contact area is the same, the actual contact point area where the two objects actually touch may vary according to the state of the contact surface, so the actual contact point area considering the state of the contact surface should be considered.

Heat transfer between the wick and the base contact surface of the evaporator is caused by conduction through the actual contact surface and through the void between the contact surface. Most of the resistance is created by the gap between the wick and the base contact surface of the evaporator. Increasing the area of the contact point of the wick and the base of the evaporator can reduce the thermal contact resistance. In other words, the thermal contact thermal resistance is related to the thermal resistance generated when the metal surface is in contact with another metal surface, and has a great difference depending on the area of the surface of the contact point.

Generally, in order to increase the actual contact area, the surface is polished and contacted, and in some cases, thermal grease is applied.

In a loop heat pipe system, the thermal contact resistance is closely related to the state of the contact interface between the heating interface of the evaporator and the sintering wick, and the liquid working fluid is supplied with heat to phase change into a vapor state. It is an important factor.

Even if the sintering wick and the base serving as the hot plate are in contact with the surface over a large area, if the contact state between the contact surfaces in the microscopic view is not good, heat transfer to the sintering wick will not be performed smoothly. The temperature of the base, which serves as a hot plate of the evaporator, is then raised to increase the temperature of the steam to the operating level of the system. Since steam acts as a medium to transfer heat to the condenser, operating at high steam temperatures will result in increased total heat resistance of the loop heat pipe system.

Therefore, in the evaporator, since the actual contact area between the sinter wick provided inside the evaporator and the internal structure of the sinter wick and the evaporator is increased, the value of the thermal contact resistance is reduced, resulting in cooling the electronic components to a low temperature. It will be the key.

By the way, in the evaporator, the prior art which attempted to increase the contact area of the structure and the wick inside is disclosed by patent application 10-2006-0024388. However, the prior art, referring to the published patent publication, although there are structural considerations for increasing the contact area between the protrusions 120 and the wick 410, which are the structures inside the evaporator, there are limitations in the shape implementation of the structures. And, due to this there is a disadvantage that the heat transfer is not made effectively because the state of the contact surface is not good.

That is, in the case of the prior art, referring to FIGS. 1, 5, and 6 (represented by FIGS. 2, 3, and 4 of the present disclosure, respectively) of the patent publication, the area of the portion where the wick and the protrusion contact each other is simply Although it appears to be relatively wider than its predecessor, the actual contact surface between the wick 410 and the contact surface of the protrusion 120 is poor because in practice the wick 410 is simply inserted and coupled between the protrusions 120. Can not do it. In other words, the contact point is not most of the contact surface, there is a disadvantage that the heat transfer from the protrusion 120 to the wick 410 does not occur effectively.

In the related art, referring to FIG. 5, which is illustrated as a contact resistance between an interface and a wick, the contact surface of the protrusion 120 and the wick 410 is enlarged by an electron microscope or the like, between the protrusion 120 and the wick 410. It is found that most of them are coupled by point contact, and thus the temperature decreases at the contact interface.

This problem of the prior art, because the protrusions 120 are integrally formed on the inner surface of the heat generating contact portion 110, which is a metal plate, there are various limitations in controlling the shape of the protrusions or the roughness of the surface. Since the plurality of wicks 410 inserted into the 120 also correspond to the shape of the protrusion 120, there are various limitations in the selection of the material or the shape.

That is, in the prior art, since the protrusions 120 are integrated with the heat generating source contact unit 110 in the evaporator, and the wicks inserted into the protrusions have corresponding shapes, it is difficult to manufacture and implement various shapes. In addition to the limitations, the contact interface between the protrusion and the wick is not good, the contact heat resistance is high, there is a problem that the cooling of the electronic component is not effective.

The present invention, as proposed to solve the above problems, in the evaporator for the loop-type bottom pipe system, it is possible to implement a variety of materials and shapes of the wick, as well as the heating fins, and thus the heating fins and wicks It is an object of the present invention to provide an evaporator for a looped bottom pipe system capable of improving the contact state therebetween.

The evaporator for a loop heat pipe (LHP) system of the present invention is an evaporator for a looped heat pipe (LHP) system, a porous wick having a plurality of voids formed therein, and Heat transfer fin having a wick coupling portion that can be coupled to the wick; The unit assembly coupled to one of the wick and the heat transfer fin: A plurality of unit assemblies are arranged in the transverse direction, the lower structure of each unit assembly is arranged so that the lower surface is located on one plane: A structure of the assembly structure Heat transfer plate coupled to the lower end: and characterized in that it comprises a cover member coupled to the heat transfer plate.

On the other hand, in the assembly structure, it is preferable to further include a spacer between neighboring unit assemblies, so that the unit assemblies are spaced apart from each other.

In addition, in the binder structure, it is preferable to further provide an intermediate wick between the unit units neighboring each other.

On the other hand, the wick is plate-shaped, the heating fin is composed of a lower member and a plurality of protrusions, the lower member is coupled to the lower side of the wick, the plurality of protrusions, from both ends of the lower member to the top It is preferable that the protrusion is formed on both sides of the wick and spaced apart from each other.

In addition, the wick is plate-shaped, the heat transfer fin, the lower member and a plurality of protrusions, the lower member is coupled to the lower side of the wick, the plurality of protrusions, from one end of the lower member It is preferable that the protrusion is formed on one side of the wick and spaced apart from each other.

On the other hand, the assembly structure, it is preferable to further comprise a pressing means for pressing the unit assemblies in the transverse direction.

According to the method of manufacturing an evaporator for a loop type heat pipe system of the present invention, since the wick and the heating fins each consist of one separate member, and the assembly structure combining them is combined with the heating plate, the heating fins and the wicks have a complicated shape or a user. It is easy to implement in the shape according to the needs of, it is possible to obtain the effect that it is possible to improve the contact state of the heating pin and the wick.

The present invention relates to an evaporator which together with a condenser, a gas conveying tube and a liquid conveying tube forms a loop heat pipe system. The description of the operation of the loop type heat pipe system is the same as that described above in the Background section.

The configuration of the evaporator 1 of one embodiment according to the evaporator for a loop type heat pipe system of the present invention will be described with reference to FIGS. 6 to 10. 6 is a schematic exploded perspective view of the evaporator 1.

The evaporator 1 includes a wick 10, a heat transfer fin 20, a unit assembly 30, a coupling structure 40, a heat transfer plate 50, and a cover member 60.

Referring to FIG. 7, the wick 10 has a thin plate shape. The wick 10 is coupled to the heat transfer fins 20 one by one, and a plurality of wicks are arranged in the transverse direction.

Since each wick 10 is a separate member, it is easy to manufacture a variety of shapes. The shape of the wick 10 can be variously modified as necessary.

The wick 10 is porous, with numerous voids therein. The working fluid is infiltrated into the voids, and is phase-changed into water vapor by heat received from the heat transfer fins 20.

The wick 10 is manufactured using metal powder, nonmetal powder, metal fiber and nonmetal fiber as a material. Heat, pressure or heat and pressure are applied to the selected material to form the desired shape. The wick is manufactured by placing the material in the mold and applying heat or pressure, or by injection.

When the material is a metal, examples are copper, brass, bronze, nickel, titanium, aluminum, stainless, and the like. When the wick 10 is made of metal, the wick 10 becomes porous by sintering. However, the time of sintering may be performed at the wick manufacturing step, or may be combined with the heat dissipation fin in the state inserted into the heat dissipation fin 20, and may be sintered, and the assembly structure 40 and the heat transfer plate 50 may be formed. Sintering may be performed in the bonding step.

And, if the material is a non-metal, for example, ceramic (ceramic) -based alumina (Al2O3). There are graphite-based activated carbon and carbon graphite. After filling non-metal powder or non-metal fiber into jig or frame, apply heat or pressure or heat and pressure at the same time to make shape.

The heat transfer fin 20 has a wick coupling portion 22 into which the wick 10 is inserted and coupled.

The heat transfer fins 20 are provided in plural and are arranged side by side in the lateral direction. The heat transfer fin 20 serves to transfer heat back from the heat transfer plate 50 to the wick 10. The heat transfer fin 10 is made of a metal having a relatively high thermal conductivity and processed using a cutting machine such as milling. However, the processing method can be variously applied.

Referring to Figure 8, each heat transfer fin 20 is composed of a lower member 24 and a plurality of projections (26, 28). The upper surface of the lower member 24 is in contact with the lower side of the wick 10, the inner surface of the projections (26, 28) are in contact with both sides of the wick (10).

The protrusions 26 located on one side and the protrusions 28 located on the other side protrude upward from both ends of the lower member 24, respectively. The protrusions 26 on one side are spaced apart from each other, and the spaces spaced apart from each other become a passage of steam generated in the wick 10. The other projections 28 are likewise spaced apart from each other.

Since the plurality of heat transfer fins 20 are each made of a separate member, and the heat transfer plate 50 is also a separate member, it processes a relatively complicated shape including the protrusions 26 and 28 and the wick coupling part 22. It is easy to do it, and it is also easy to adjust the roughness of a process surface to a desired degree.

The unit assembly 30 is made of one wick 10 and one heat transfer fin 20.

In particular, when the material of the wick 10 is a metal, the wick 10 and the heat transfer fins 20 are coupled to each other by metallic bonding. In this case, the metallic coupling is not simply inserted or coupled by interference fitting, etc., but refers to a state in which metallic coupling is made at an interface with the heat transfer fins 20 while heat is applied. Due to this configuration, the heat resistance in the heat transfer from the heat transfer fins 20 to the wicks 10 is greatly reduced.

The assembly structure 40, the unit assembly 30 is made up in the transverse direction. The unit assemblies 30 arranged in the transverse direction are arranged such that each lower side is located on one virtual plane. This is a configuration for coupling to the flat heat transfer plate (50).

In the present embodiment, the assembly structure 40 further includes an intermediate wick 12 between the unit assemblies 30 adjacent to each other. The intermediate wick 12 is preferably arranged such that its lower side is in contact with the heat transfer plate. The intermediate wick 12 is the same as the wick 10 described above, except that the position of the intermediate wick 12 is different.

The intermediate wick 12 receives heat from the heat transfer plate 50 coupled to the lower side thereof and the heat transfer fins 20 coupled to both sides thereof. By the heat received, the working fluid inside is changed into steam, and escapes between the protrusions of the heat transfer fin 20.

The heat transfer plate 50 is made of a metal material and is coupled to the lower end of the assembly structure 40. The lower surface of the heat transfer plate 50 is a part in contact with a heat source (not shown), and receives heat from the heat source. A heat source is an electronic component that generates heat during operation, for example, a computer central processing unit (CPU), a graphics card chipset, and the like.

The heat transfer plate 50 and the assembly structure 40 are mutually coupled to each other through heat and physical bonding. In this case, it is preferable to apply the heat-transfer plate 50 to the bottom surface of the assembly structure 40 by applying a metal melting technique such as brazing and soldering according to the material or properties of the heat-transfer plate 50.

The cover member 60 is coupled to the upper portion of the heat transfer plate 50. The cover member 60 forms an inner space together with the heat transfer plate 50, and the assembly structure 40 is positioned in the inner space. One side of the cover member 60 is formed with a steam line coupling hole 62 to which the steam line is coupled, and a liquid line coupling hole 64 to which the liquid line is coupled is formed at one side of the upper surface.

The operation of the evaporator 1 for the loop type heat pipe system having the above-described configuration will be described.

The working fluid in the liquid state is introduced into the liquid line through the coupling line 64 of the cover member 60 of the evaporator 1. The introduced working fluid seeps into numerous voids formed inside the porous wick 10 and the intermediate wick 12. The heat of the heat source transferred to the heat transfer fins 20 through the heat transfer plate 50 is transferred to the wick 10 and the intermediate wick 12 again to change the working fluid in the gas phase into a gas.

Since the generated steam is mutually coupled between the wicks, the intermediate wicks 10 and 12, and the projections 26 and 28 of the heat transfer fin 20, the vapor passages are secured, the cover member 60 passes through the steam passage. It can be exited to the steam line coupling hole 62).

The feature of the configuration of the evaporator for the loop type heat pipe system of the present invention is that the heating fins to which one wick is coupled are formed in a separate member, and a plurality of unit assemblies in which one wick and one heating fin are combined are arranged. And is coupled to the heating plate.

Since the heating fins and wicks are formed as separate individual parts, and then combined with each other to form a single unit assembly, it is not only possible to manufacture the heating fins and wicks in various shapes and sizes, but also to heat or heat the heating fins and wicks. Since it is easy to firmly bond to each other by pressure, there is an advantage that it is possible to minimize the contact thermal resistance at the contact surface.

That is, compared with the prior art in which all the projections were formed integrally directly on the heat transfer plate, in the case of the present invention, since the heat transfer fins are processed as one separate member, processing of a complicated shape is relatively easy and considerably thin. It is also possible to process to have a thickness.

This ease of processing can increase the heating area and the steam generating area, and at the same time minimizes the contact heat resistance between the heating fins and the wicks having protrusions, thereby reducing the total heat resistance of the loop heat pipe system. .

In addition, when the wick is made of a metallic material, the wick and the heat-transfer fins, and the heat-transfer fins and the heat-transfer plate, are not simply in contact with each other at the mutually contacting surfaces, but rather by heat or pressure or heat and pressure. As a result, the contact thermal resistance at the mating surface is reduced.

However, in the prior art, due to limitations in the shape of the protrusions integrally formed on the sintered wick and the base, the sintered wicks were simply inserted into the overall protrusions and joined. Therefore, although the surface area of the contact surface of the sintered wick and the base appears to be increased in appearance, the bonding at the contact surface of the protrusion of the sintered wick and the base is mostly point contact, not surface contact, and thus the contact surface is not good. In practice, the heat resistance at the contact surface is relatively high, which makes it difficult to transfer heat from the heat source to the sintered wick.

On the other hand, in the case of the present invention, since the wick and the heating fins do not directly contact the heat source, it is possible to freely adjust the structure, width, thickness, and the like of the heating fins. That is, in the shape of the wick and the heat transfer fin, there is an advantage that it is easy to adjust the thickness and the total width, etc. so as to secure a wider heat transfer area and a steam generation area.

11 shows a modified assembly structure 40a compared to the previous embodiment. Other configurations not shown are the same as in the previous embodiment. 12 is a cross-sectional view of the assembly structure 40a of FIG.

In the assembly structure 40a of the present embodiment, the spacer 14 is provided between the neighboring unit assemblies 30a so that the unit assemblies 30a are spaced apart from each other. The spacer 14 is shaped like a comb. The space between the unit assemblies 30a secured by the spacers 14 is used as a steam passage to help the steam generated in the wick 10 to be discharged to the outside more smoothly.

The heat transfer fins 20a to which the wicks 10 are coupled have a considerably thinner thickness as compared with the previous embodiment. Since the heating fins 20a are individually processed, the lower member 24a and the protrusions 26a and 28a may be processed to a considerably thin thickness. The vapor passage 15 is secured between the unit assemblies 30a by the spacers 14.

13 shows an assembly structure 40b having a spacer 16 of a different shape than the previous embodiment. Other configurations not shown are the same as in the previous embodiment. 12 is a cross-sectional view of the assembly structure 40a of FIG.

Each portion of the heat transfer fin 20b, that is, the lower member 24b and the projections 26b and 28b, is thinner in thickness. The vapor passage 17 secured by the spacer 16 is provided between the unit assemblies 30b.

15 to 17 show an embodiment in which the modified heating fin 20c is employed. Compared with the heat transfer fins 20 illustrated in FIG. 8, the heat transfer fins 20c of the present embodiment have one side protrusion removed and consist of only the other side protrusion 28c and the lower member 24c. 16 and 17 illustrate the unit assembly 30c in which the heat transfer fins 20c and the wick 10 are coupled, and the assembly structure 40c in which the unit assemblies 30c are disposed in the transverse direction, respectively.

FIG. 18 shows, as another embodiment according to the present invention, that the assembly structure 40 is further provided with a rectangular frame 42 as a pressing means.

The rectangular frame 42 as the pressing means pressurizes the unit assemblies 30 constituting the assembly structure in the transverse direction. The transverse direction means a direction in which the unit assemblies 30 are arranged side by side. Pressing means capable of mutually pressurizing the unit assembly 30 serves to shrink the diameter of the voids present in the wick 10. On the other hand, although not shown, as the pressing means, a clamp that can hold the assembly structure from both sides and hold it with a screw or the like may be provided. In addition, after providing a through-hole penetrating the assembly structure in the transverse direction, it may be configured to press the bolt screw therein to pressurize the assembly structure in the transverse direction.

In FIG. 19, the length of the diameter of the space | gap 18 which existed inside the wick 10 before pressurization was reduced to D1 by pressing in the arrow direction in D0. On the other hand, the wick 10 serves to transfer the working fluid to the evaporation interface by capillary pressure. At this time, the contraction of the diameter of the air gap 18 has the advantage that the capillary pressure is increased to facilitate the movement of the working fluid.

1 is a conceptual diagram of a prior art loop type heat pipe system 110,

2 to 4 are views for explaining the prior art,

5 is a view for explaining a state of the contact surface between the interface and the wick of FIGS.

6 is a schematic exploded perspective view of an evaporator for an loop type heat pipe system according to an embodiment of the present invention;

FIG. 7 is a view illustrating a wick, a heating fin, and a unit assembly of the evaporator of FIG. 6, respectively.

10 is a view of the assembly structure of the evaporator of FIG.

11 and 12 respectively show a combined structure and a cross-sectional view of another embodiment of a loop type heat pipe system according to the present invention;

13 and 14 are a cross-sectional view, respectively, of a combination structure of another embodiment of a loop heat pipe system according to the present invention;

15 to 17, respectively, illustrating the heating fins, unit assemblies, assembly structure of another embodiment of the loop type heat pipe system according to the present invention.

18 is a view showing another embodiment according to the present invention further comprising a rectangular frame as a pressing means in the assembly structure,

19 is a view for explaining that the diameter of the gap is reduced by the pressing means.

Claims (6)

Evaporator for Looped Heat Pipe (LHP) systems, Porous wick with a plurality of voids formed therein, A heat transfer fin having a wick coupling portion to which the wick can be coupled; Unit unit is combined with one of the wick and one of the heating fins: A plurality of unit assemblies are arranged in the transverse direction, the assembly structure is arranged so that the lower side of each unit assembly is located on one plane: Heat transfer plate coupled to the lower end of the assembly structure: And Evaporator for a loop type heat pipe system, characterized in that it comprises a cover member coupled to the heat transfer plate. The method of claim 1, The evaporator of claim 1, further comprising a spacer between neighboring unit assemblies such that the unit assemblies are spaced apart from each other. The method of claim 1, In the assembly structure, evaporator for a loop type heat pipe system, characterized in that further comprising an intermediate wick between the neighboring unit assembly. The method of claim 1, The wick is plate-shaped, The heating fin is composed of a lower member and a plurality of protrusions, The lower member is coupled to the lower side of the wick, The plurality of protrusions, protruding upward from both ends of the lower member is located on both sides of the wick, spaced apart from each other evaporator for a loop type heat pipe system. The method of claim 1 The wick is plate-shaped, The heat transfer fin is composed of a lower member and a plurality of protrusions, The lower member is coupled to the lower side of the wick, The plurality of protrusions, protruding upward from one end of the lower member is located on one side of the wick, spaced apart from each other evaporator for a loop type heat pipe system. The method of claim 1, The assembly structure, the evaporator for a loop type heat pipe system, characterized in that further comprising a pressing means for pressing the unit assemblies in the transverse direction.

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