US20100163212A1

US20100163212A1 - Flat loop Heat pipe

Info

Publication number: US20100163212A1
Application number: US12/461,787
Authority: US
Inventors: Chi-Te Chin
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-12-26
Filing date: 2009-08-25
Publication date: 2010-07-01
Also published as: TW201024648A; TWI371566B

Abstract

A flat loop heat pipe is formed of a first capillary core, a second capillary core, a first support member, and a second support member. The first capillary core and the first support member constitute an evaporation room. The second capillary core and the second support member constitute a compensation room. In light of this structure, it is not difficult to activate circulation of thermal dissipation under low-watt heat source and the first capillary core can avoid dry-out phenomenon.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to heat-dissipating technology, and more particularly, to a flat loop heat pipe.
2. Description of the Related Art
A conventional loop heat pipe (LHP) is an effective heat-dissipating device and generally composed of an evaporator, a vapor line, a condenser, and a liquid line, all of which are connected and communicated with one another to become a loop containing a working fluid. The evaporator includes a capillary structure connected with a heat source. A compensation chamber is provided between the liquid line and the capillary structure. When the evaporator absorbs the heat from the heat source, the working fluid inside the LHP also absorbs the heat from the heat source to produce vapors. The vapors flow through a pipeline from the evaporator toward condenser chamber and then give out the heat at the condenser to be condensed and converted into liquid, and then the liquid drive into the evaporator to complete a cycle. In light of the aforesaid operation, the working fluid repeatedly adsorb heat to evaporate and give out heat to condense for thermal dissipation.
The capillary structure in the evaporator of the conventional LHP is generally made of sintered powders. However, the sintered powders are solid to have greater flow resistance, such that it is difficult to activate the cycle of the thermal dissipation when the heat source is low-watt. In addition, when the evaporation rate of the working fluid in the evaporator is larger than the reflux rate of the liquid line, it is difficult to suck the working fluid from the compensation chamber to the evaporator, such that the working fluid in the evaporator is subject to dry-out to weaken the heat-dissipating performance of the LHP.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a flat LHP, which can prevent circulation of thermal dissipation from difficult activation.
The secondary objective of the present invention is to provide a flat LHP, which can enhance the heat-dissipating performance.
The foregoing objectives of the present invention are attained by the flat LHP composed of a container, a first capillary core, a second capillary core, a circulatory pipeline, and a working fluid. The container includes a case, a cover, and a chamber formed therein between the case and the cover. The case has two openings, one of which is a vapor outlet and the other is a liquid inlet. The first capillary core is sleeve-shaped and mounted below the chamber, having a plurality of pores disposed thereon and an opening connected with the vapor outlet in airtight in such a way that an evaporation room is formed. The second capillary core is also sleeve-shaped and mounted above the chamber, having a plurality of pores disposed thereon, a lower part stopped against the first capillary core, and an opening stopped against the liquid inlet in such a way that a compensation room is formed. The circulatory pipeline includes a vapor line, a condensation line, a liquid reflux line, and an injection port. The vapor line has one end connected with the vapor outlet in airtight. The condensation line has one end connected with the vapor line in airtight. The liquid reflux line has two ends, one of which is connected with the condensation line in airtight and the other end is connected with the liquid inlet in airtight. The injection port is located at the vapor line or the liquid reflux line. The working fluid is infused into the circulatory pipeline to become a medium of heat absorption and dissipation.
In light of the above structure, vapors generated from the working fluid under a heat source of relatively low wattage can still travel to the evaporation room, such that the flow resistance of the vapors is too little to cause overgreat pressure partially inside the evaporation room and to make it difficult for activating the circulation of thermal dissipation. Besides, the second capillary core is stopped against the first capillary core without contact with the heat source, such that no evaporation happens and then the second capillary core keeps absorbing the working fluid located in the compensation room to reinforce supplement of the working fluid required by the first capillary core. In this way, it can prevent the evaporation room from dry-out to further enhance the heat-dissipating performance of the flat LHP.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially sectional view of a preferred embodiment of the present invention.

FIG. 2 is an exploded view of the preferred embodiment of the present invention.

FIG. 3 is a perspective view of a part of the preferred embodiment of the present invention.

FIG. 4 is another perspective view of a part of the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1-4, a flat LHP 1 constructed according to a preferred embodiment of the present invention is composed of a container 20, a first capillary core 30, a second capillary core 40, a first support member 50, a second support member 60, a circulatory pipeline 70, and a working fluid 80.
The container 20 includes a case 21 and a cover 22. A chamber 23 is formed inside the container 20 and between the case 21 and the cover 22. The case 21 has two openings, which are a vapor outlet 211 and a liquid inlet 212 respectively. The distance between a center of the vapor outlet 211 and a bottom side of the base 21 is smaller than the distance between a center of the liquid inlet 212 and the bottom side of the case 21. The vapor outlet 211 and the liquid inlet 212 are mounted to a left side and a right side of the base 21.
Each of the first and second capillary cores 30 and 40 is structurally capillary and thin sleeve-shaped, having a close end 31(41) at one end thereof, an open end 32(42) at the other end thereof, and a plurality of pores disposed thereon. Each of the two capillary cores 30 and 40 can be made of a porous material, which can be sintered powers, a fine groove, a net, a fiber, or a composition of those materials. In this embodiment, each of the two capillary cores 30 and 40 is a metallic thin net having above 100 meshes.
Each of the first and second support members 50 and 60 is a sleeve-shaped metallic thin net having less than 20 meshes, a close end 51(61), an open end 52(62), and a plurality of pores disposed thereon. The first capillary core 30 is sleeved onto the first support member 50, and the second capillary core 40 is sleeved onto the second support member 60. In this way, the first and second capillary cores 30 and 40 can be well supported by the first and second support members 50 and 60 respectively.
The first capillary core 30 is sleeved into the first support member 50 by that the close end 31 is stopped against the close end 51, thus forming an evaporation module 100. The evaporation module 100 is mounted to a bottom side of the chamber 23 to enable the open ends 32 and 52 to face and be connected with the vapor outlet 211 in airtight in such a way that an evaporation room 33 is formed inside the first capillary core 30. The second capillary core 40 is sleeved into the second support member 60 by that the close end 41 is stopped against the close end 61, thus forming a compensation module 200. The compensation module 200 is mounted to a top side of the chamber 23 to enable the open ends 42 and 62 to face and be connected with the liquid inlet 212 in airtight in such a way that a compensation room 43 is formed inside the second capillary core 40. The sum of the height of the evaporation module 100 and of the compensation module 200 is larger than the height of the chamber 23, such that the evaporation and compensation modules 100 and 200 squeeze each other. In other words, the contact area between a bottom side of the evaporation module 100 and an internal bottom side of the container 20 and between a top side of the evaporation module 100 and a bottom side of the compensation module 200 is relatively larger; the contact area between a bottom side of the compensation module 200 and the top side of the evaporation module 100 and between a top side of the compensation module 200 and an internal top side of the container 20 is relatively larger.
The circulatory pipeline 70 includes a vapor line 71, a condensation line 72, a liquid reflux line 73, and an injection port 74. The vapor line 71 has one end connected with the vapor outlet 211 in airtight for guiding flowage of vapors. The condensation line has one end connected with the vapor line 71 in airtight. A heat sink 75 can be additionally mounted to an external periphery of the condensation line 72 for reinforcing thermal dissipation and condensation of the condensation line 72. The heat sink 75 can be fins, a cooling fan, or the like. In this embodiment, the heat sink is fins. The liquid reflux line 73 has two ends, one of which is connected with the other end of the condensation line 72 in airtight and the other of which is connected with the liquid inlet 212 in airtight. The injection port 74 is located at the vapor line 71 or the liquid reflux line 73 for injecting the working fluid 80 and vacuating and sealing the flat LHP 1 therethrough.
The working fluid 80, which can be water, methanol, ammonia, or Freon, is injected through the injection port 74 into the flat LHP 1.
The flat LHP 1 can be applied to a central processing unit (CPU), a light emitting diode (LED), or another euthermic element. Referring to FIG. 1 again, when the bottom side of the case 21 is in contact with a heat source (not shown), like a CPU or an LED, the heat source transmits the heat to the container 20 and the evaporation module 100. The working fluid 80 existing in the first capillary core 30 absorbs the heat from the heat source. When the heat absorbed by the working fluid 80 is greater than its latent heat, the working fluid 80 proceeds with phase change to transform itself into the vapors from liquid and then to fill the evaporation room 33. Next, the vapors flow into through the vapor outlet 211 into the vapor line 71 from the evaporation room 33 and then flow along the vapor line 71 into the condensation line 72. When the vapors are located at the condensation line 72, the heat in the vapors is dissipated for heat exchange with outside and the efficiency of such thermal dissipation is enhanced by the heat sink 75. After the heat in the vapors is fully released, the working fluid 80 proceeds with another phase change to transform itself into liquid from the vapors. In the meantime, the working fluid 80 transformed into liquid is pushed by the vapors and then flow to the liquid reflux line 73 and finally back to the compensation room 43. At last, the working fluid 80 returns to the first capillary core 30 by means of the capillary action of the second capillary core 40 for again absorbing the heat of the heat source. In this way, a working cycle is formed.
During the above working cycle, the first support member 50 can upheave the first capillary core 30 to form the evaporation room 33, such that the flow resistance of the vapors can be reduced and even when the heat source is low-watt, the flowage of the vapors can still cause a circulatory thermal dissipation without any difficulty. Besides, the second capillary core 40 keeps absorbing the working fluid 80 and then transmit the same to the first capillary core 30 to prevent the first capillary core 40 from drought.
It is to be noted that the evaporation module 100 is formed of the first capillary core 30 and the first support member 50; however, if the first capillary core 30 is rigid enough, it will be not necessary to mount the first support member 50 into the first capillary core 30. Likewise, the compensation module 200 is formed of the second capillary core 40 and the second support member 60; however, if the second capillary core 40 is rigid enough, it will be not necessary to mount the second support member 60 into the second capillary core 40. The sum of the height of the first and second capillary cores 30 and 40 is preferably larger than that of the chamber 23 in such a way that the first and second capillary cores 30 and 40 can squeeze each other to enable the larger contact area therebetween.
In addition, the present invention is to primarily enable the hollow compensation and evaporation rooms 43 and 33 to be spaced from each other by a capillary structure, such that only one sleeve-shaped capillary core mounted to the bottom side of the container and connected with the vapor outlet 211 in airtight can also space the compensation and evaporation rooms 43 and 33 from each other. This sleeve-shaped capillary core can lessen the flow resistance of the vapors and enable the flowage of the vapors to do circulatory thermal dissipation without any difficulty while the heat source is low-watt.
Although the present invention has been described with respect to a specific preferred embodiment thereof, it is no way limited to the details of the illustrated structures but changes and modifications may be made within the scope of the appended claims.

Claims

1. A flat LHP comprising:

a container having a case, a cover, and a chamber formed therein between the case and the cover, the chamber having two opening, one of which is a vapor outlet and the other is a liquid inlet, the distance between a center of the vapor outlet and a bottom side of the case being smaller than the distance between a center of the liquid inlet and the bottom side of the case, the cover being in airtight connection with the case;

at least one sleeve-shaped capillary core having a plurality of pores and located at a bottom side of the container and in airtight connection with the vapor outlet;

a circulatory pipeline having a vapor line, a condensation line, and a liquid reflux line, the vapor line connected with the vapor outlet in airtight for guiding flowage of vapors, the condensation line having an end in airtight connection with the vapor line, the liquid reflux line having two ends, one of which is in airtight connection with the other end of the condensation line and the other of which is in airtight connection with the liquid inlet; and

a working fluid infused into the circulatory pipeline to become a medium of heat absorption and release.

2. The flat LHP as defined in claim 1, wherein the at least one capillary core comprises a close end and an open end, the open end being in airtight connection with the vapor outlet.

3. The flat LHP as defined in claim 2 further comprising at least one sleeve-shaped support member, wherein the at least one support member has a close end, an open end, and a plurality of pores, the at least one support member being sleeved into the at least one capillary core by their two close ends stopped against each other to become an evaporation module.

4. The flat LHP as defined in claim 1, wherein the at least one capillary core is two in number, one of which is a first capillary core and the other is a second capillary core, the first capillary core being located at a bottom side of the container and in airtight connection with the vapor outlet, the second capillary core being located at a top side of the container and in airtight connection with the liquid inlet.

5. The flat LHP as defined in claim 4 further comprising two sleeve-shaped support members, one of which is a first support member and the other is a second support member, wherein each of the support members has a close end, an open end, and a plurality of pores disposed thereon, the first support member being sleeved into the first capillary core by that their close ends are stopped against each other in such a way that an evaporation module is formed, the second support member being sleeved into the second capillary core by that their close ends are stopped against each other in such a way that a compensation module is formed.

6. The flat LHP as defined in claim 4, wherein the sum of height of the first and second capillary cores is larger than that of the container.

7. The flat LHP as defined in claim 5, wherein the sum of the height of the evaporation and compensation modules is larger than that of the container.

8. The flat LHP as defined in claim 1, wherein the condensation line comprises a heat sink mounted to an external periphery thereof.

9. The flat LHP as defined in claim 1 further comprising an injection port, which is formed between the evaporation line and the liquid reflux line.

10. The flat LHP as defined in claim 1, wherein the vapor outlet and the liquid inlet are located at a left side and a right side of the container respectively.

11. The flat LHP as defined in claim 4, wherein each of the first and second capillary cores is a metallic net having at least 100 meshes.

12. The flat LHP as defined in claim 5, wherein each of the first and second support members is a metallic net having at least 20 meshes.

13. A flat LHP comprising:

a container having a chamber defining two openings, one of which is a vapor outlet and the other is a liquid inlet;

a sleeve-shaped evaporation module having a plurality of pores and an evaporation room formed therein, the evaporation room being located at a bottom side of the container and in airtight connection with the vapor outlet;

a circulatory pipeline having an end in airtight connection with the vapor outlet and the other end in airtight connection with the liquid inlet; and

14. The flat LHP as defined in claim 13 further comprising a sleeve-shaped compensation module, wherein the compensation module has a plurality of pores disposed thereon and a compensation room formed therein, the compensation room being located at a top side of the container and in airtight connection with the liquid inlet.