US20210302105A1

US20210302105A1 - Loop heat pipe structure

Info

Publication number: US20210302105A1
Application number: US16/835,184
Authority: US
Inventors: Tzyy-Pyng Lin; Fu-Kuei Chang
Original assignee: Asia Vital Components Co Ltd
Current assignee: Asia Vital Components Co Ltd
Priority date: 2020-03-30
Filing date: 2020-03-30
Publication date: 2021-09-30

Abstract

A loop heat pipe structure includes an evaporation chamber body and a tube body. The evaporation chamber body has an upper case body and a lower board body. The upper case body and the lower board body together define a closed chamber in which a capillary structure is disposed. The evaporation chamber body has an outlet and an inlet in communication with the closed chamber. A working fluid is filled in the closed chamber. Two ends of the tube body are respectively connected with the outlet and the inlet. The upper case body and the lower board body of the evaporation chamber body and the tube body are made of various materials in combination with each other so as to improve the shortcoming of the conventional loop heat pipe that the strength is insufficient and reduce the total weight of the loop heat pipe.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a loop heat pipe structure, and more particularly to a loop heat pipe structure, in which titanium or stainless steel material is used instead of the upper cover body and the condensation tube body of the evaporation chamber body of the conventional loop heat pipe so as to enhance the structural strength of the entire loop heat pipe and reduce the total weight of the loop heat pipe.

2. Description of the Related Art

Along with the increase of the performance of the current electronic apparatuses, the heat generated by the electronic components for signal processing and operation has become higher than the conventional electronic components. The most often used heat dissipation components include heat pipe, heat sink, vapor chamber, etc. These heat dissipation components are in direct contact with the heat generation electronic components to enhance the heat dissipation performance so as to prevent the electronic components from burning out due to over-heating.
A fan with forced heat dissipation effect can be further disposed to dissipate the heat of the heat dissipation component. The fan can truly enhance the heat dissipation performance. However, it is not always practicable to arrange a fan in a limited space. Therefore, the space problem is also a key point needing to be taken into consideration.
In addition, some manufacturers in this field provide a loop heat pipe structure in concept of heat pipe vapor-liquid circulation. The loop heat pipe structure is composed of an evaporation chamber body and a condensation device in combination with the evaporation chamber body. A tube body is connected between the evaporation chamber body and the condensation device to form the loop heat pipe structure as a loop module. The loop heat pipe structure has the advantage that the loop heat pipe structure can provide a heat dissipation device with better evaporation-condensation circulation effect itself. A capillary structure is disposed in the evaporation chamber body for the working fluid to flow back and store. The capillary structure is formed with multiple channels for the vapor to flow. At least one face of the evaporation chamber body is in contact with a heat source to conduct the heat. After the working fluid in the capillary structure of the evaporation chamber body is heated and evaporated, the vapor working fluid flows out from the channels and spreads through the tube body connected between the evaporation chamber body and the condensation device to the condensation device. Finally, the vapor working fluid is condensed by the condensation device into liquid working fluid to flow back to the evaporation chamber body to continue the circulation.
A common loop heat pipe structure body is mainly made of copper or aluminum material. Copper has a property of high heat conductivity. However, copper is soft and has heavy weight. Aluminum has the advantage of light weight, but the heat conductivity of aluminum is poorer. Therefore, the current loop heat pipe structure fails to have all the features of good heat dissipation effect and light weight and good structural strength.
It is therefore tried by the applicant to provide a loop heat pipe structure to improve the shortcomings of the conventional loop heat pipe.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide a loop heat pipe structure, which can reduce the total weight and keep having high heat conductivity.
To achieve the above and other objects, the loop heat pipe structure of the present invention includes an evaporation chamber body and a tube body.
The evaporation chamber body has an upper case body and a lower board body. The upper case body and the lower board body together define a closed chamber in which a capillary structure is disposed. The evaporation chamber body has an outlet and an inlet in communication with the closed chamber. A working fluid is filled in the closed chamber. The tube body has a first end, a second end and a middle section. The first and second ends are respectively positioned at two ends of the middle section. The first and second ends are respectively connected with the outlet and inlet of the evaporation chamber body. The upper case body, the lower board body and the tube body are made of materials selected from a group consisting of titanium, stainless steel, copper, ceramic, aluminum, iron and graphite. The titanium material is commercial pure titanium or titanium alloy.
The upper case body and the lower board body of the evaporation chamber body and the tube body are made of various materials in combination with each other so as to improve the shortcomings of the conventional loop heat pipe that the strength is poor and the weight is heavy.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein:

FIG. 1 is a perspective exploded view of a first embodiment of the loop heat structure of the present invention;

FIG. 2 is a sectional assembled view of the first embodiment of the loop heat structure of the present invention;

FIG. 3 is a sectional assembled view of a second embodiment of the loop heat structure of the present invention;

FIG. 4 is a sectional assembled view of a third embodiment of the loop heat structure of the present invention; and

FIG. 5 is a sectional view showing the operation of the loop heat structure of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 and 2. FIG. 1 is a perspective exploded view of a first embodiment of the loop heat structure of the present invention. FIG. 2 is a sectional assembled view of the first embodiment of the loop heat structure of the present invention. As shown in the drawings, the loop heat pipe structure 1 of the present invention includes an evaporation chamber body 11 and a tube body 12.
The evaporation chamber body 11 has an upper case body 111 and a lower board body 112. The upper case body 111 and the lower board body 112 together define a closed chamber 113 in which a capillary structure 2 is disposed. The evaporation chamber body 11 has an outlet 114 and an inlet 115 in communication with the closed chamber 113. A working fluid 3 is filled in the closed chamber 113.
The tube body 12 has a first end 121 and a second end 122 and a middle section 123. The first and second ends 121, 122 are respectively positioned at two ends of the middle section 123. The first and second ends 121, 122 are respectively connected with the outlet and inlet 114, 115 of the evaporation chamber body 11. A heat dissipation unit 4 is disposed on outer side of the tube body 12. The heat dissipation unit 4 serves to enhance the condensation efficiency of the tube body 12. The heat dissipation unit 4 can be a radiating fin assembly or a heat sink or any other form of heat dissipation unit 4 or multiple cooling tube bodies capable of increasing heat dissipation or cooling area. In this embodiment, the heat dissipation unit 4 is, but not limited to, a radiating fin assembly for illustration purposes. The upper case body 111, the lower board body 112, the tube body 12 and the capillary structure 2 are made of a material selected from a group consisting of titanium, stainless steel, copper, ceramic, aluminum, iron and graphite.
The closed chamber 113 further has at least one vapor passage 116 and a compensation chamber 117. The vapor passage 116 is selectively disposed on a wall face of the evaporation chamber body 11, which faces the capillary structure 2 or disposed on one side of the capillary structure 2, which faces the evaporation chamber body 11. In addition, one end of the vapor passage 116 is correspondingly connected with the outlet 114. The working fluid 3 is converted between vapor phase and liquid phase. The vapor-phase working fluid 31 and the liquid-phase working fluid 32 are circulated within the entire interior of the loop heat pipe structure 1. The evaporation chamber body 11 is a flat-plate evaporation chamber body. The compensation chamber 117 is correspondingly disposed in parallel to the capillary structure 2.
The capillary structure 2 has multiple channels 21 in adjacency to the lower board body 112. Each channel 21 has an open side 211 and a closed side 212. The open side 211 is attached to the lower board body 212. The open side 211 has a width smaller than that of the closed side 212.
The capillary structure 2 is formed of sintered powder. The powder is selected from a group consisting of copper, aluminum, titanium and plastic fiber.
The titanium material is commercial pure titanium or titanium alloy. The commercial pure titanium and titanium alloy have nine properties of high specific strength, excellent anticorrosion ability, low elastic modulus, good heat-resistance, excellent low-temperature property, high biological compatibility, low heat conductivity, colorful oxide film and non-magnetic. The commercial pure titanium and titanium alloy are widely applied to civil industries, petrochemical industries, aerospace industries, military industries, medical industries, etc. In recent years, various countries have developed over 100 types of titanium alloys. There are about 40˜50 types of actually commercialized titanium alloys. According to the elements contained in the titanium alloys, the titanium alloys can be generally classified into three major types, that is, α-type titanium, α-β-type titanium and β-type titanium: (1) α-type titanium can be classified into commercial pure titanium, α titanium and near α titanium according to the sort and content of the contained element. The commercial pure titanium only contains minor elements of oxygen, carbon, nitrogen, hydrogen, iron, etc. without other alloy element. In pure titanium, oxygen is gap-type element. The content of oxygen greatly affects the strength of the pure titanium. In general, 0.1 wt % oxygen will about 100˜120 MPa increase the strength of the titanium. According to the content of oxygen, the commercial pure titanium can be classified into four ranks (Gr.1˜Gr.4). Grade 1 pure titanium has oxygen content lower than 0.18 wt % and has the advantages of low strength, excellent ductility and good formability and is mainly applied to building roof and plate-type heat exchanger. Grade 2 pure titanium has tension strength ranging from 350-450 MPa and is the most often used one of the four types of pure titanium. Grade 2 pure titanium is often applied to manufacturing of seam pipe, seamless pipe and chemical engineering tank. Grade 3 pure titanium has strength ranging from about 500-600 MPa and is mainly applied to chemical engineering pressure tank. Grade 4 pure titanium has strength proximate to 700 MPa, which is highest among the four types of pure titanium. Grade 4 pure titanium is mainly applied to some fastening members and complicated components needing to form at about 300° C. α titanium contains α stabilizing elements (Al, O) and neutral elements (Sn, Zr). After annealed, the texture is single-phase a having good texture stability, heat-resistance and weldability and having strength higher than industrial pure titanium. In order to satisfy strength requirement, neutral element will be added into α-type titanium alloy to reinforce the same. The most typical example is Gr.6(Ti-5Al-2.5Sn) having good fracture toughness at room temperature and high temperature and good heat-resistance and long-term working temperature of about 500° C. In addition, low-interstice Ti-5Al-2.5Sn is applicable to low-temperature environment. Pure titanium and titanium alloy have nine properties of high specific strength, excellent anticorrosion ability, low elastic modulus, good heat-resistance, excellent low-temperature property, high biological compatibility, low heat conductivity, colorful oxide film and non-magnetic. Therefore, different types of commercial pure titanium or titanium alloys or stainless steel are selectively used for different sections of the loop heat pipe. According to the different features of commercial pure titanium and titanium alloys or stainless steel, the conventional copper or aluminum material can be replaced. This has the advantages that the heat dissipation efficiency and structural strength of the entire loop heat pipe are enhanced and the weight of the loop heat pipe is reduced.
Please refer to FIG. 3, which is a sectional assembled view of a second embodiment of the loop heat structure of the present invention. The second embodiment is partially identical to the first embodiment in structure and thus will not be redundantly described hereinafter. The second embodiment is different from the first embodiment in that the outlet 114 and the inlet 115 are disposed on different sides of the evaporation chamber body 11. The second end 122 of the tube body 12 enters the closed chamber 113 from the inlet 115 of the evaporation chamber body 11 and extends to one side distal from the compensation chamber 117.
Please refer to FIG. 4, which is a sectional assembled view of a third embodiment of the loop heat structure of the present invention. The third embodiment is partially identical to the first embodiment in structure and thus will not be redundantly described hereinafter. The third embodiment is different from the first embodiment in that the evaporation chamber body 11 has a liquid passage 118. One end of the liquid passage 118 is connected with the inlet 115. The liquid passage 118 is disposed on one side of the capillary structure 2. In addition, the liquid passage 118 and the vapor passage 116 are respectively correspondingly disposed on upper and lower sides of the capillary structure 2.
Please refer to FIG. 5, which is a sectional view showing the operation of the loop heat structure of the present invention. As shown in the drawing, one side (heat contact face) of the evaporation chamber body 11 of the loop heat pipe structure 1 of the present invention is in contact with a heat source 5. The capillary structure 2 is correspondingly disposed in a section of the evaporation chamber body 11 in contact with the heat source 5. The capillary structure 2 contains the liquid-phase working fluid 32 therein. When the evaporation chamber body 11 contacts the heat source 3 and absorbs the heat generated by the heat source 3, the internal capillary structure 2 is heated and the liquid-phase working fluid 32 contained in the capillary structure 2 is evaporated to spread from the vapor passage 116 and leave the capillary structure 2. One end of the vapor chamber 116 is directly connected with the outlet 114 of the evaporation chamber body 11 so that the vapor-phase working fluid 31 directly spreads from the outlet 114 to outer side of the evaporation chamber body 11. The first end 121 of the tube body 12 is connected with the outlet 114 so that the vapor-phase working fluid 31 enters the tube body 12. The vapor-phase working fluid 31 is cooled and condensed in a position where the heat dissipation unit 4 is disposed on (stringed by) the tube body 12. The second end 122 of the tube body 12 is connected with the inlet 115 of the evaporation chamber body 11 so that the liquid-phase working fluid 32 is guided to flow back into the evaporation chamber body 11. When the liquid-phase working fluid 32 is evaporated, a pressure difference is created. By means of the pressure difference and the capillary attraction, the liquid-phase working fluid 32 can be guided to flow back into the capillary structure 2. Moreover, the inlet 115 is correspondingly disposed on upper side of the capillary structure 2 so that due to gravity, the liquid-phase working fluid 32 can further directly fall into the capillary structure 2 to continue the vapor-liquid circulation.
Alternatively, any other heat dissipation component (not shown) capable of enhancing condensation effect can be connected with or disposed around the tube body 12 so as to enhance the condensation efficiency.
The other object of the present invention is to change the relative relationship between the outlet 114 and the inlet 115 of the evaporation chamber body 11 and the capillary structure 2. When the liquid-phase working fluid 32 flows back into the evaporation chamber body 11, the liquid-phase working fluid 32 is first guided into the capillary structure 2 serving as a vapor wick. That is, the capillary structure 2 is directly disposed under the inlet 115 so that after the liquid-phase working fluid 32 flows back, the liquid-phase working fluid 32 first enters the capillary structure 2 and is stored therein. After the water content of the capillary structure 2 is saturated, the excessive liquid-phase working fluid 32 will enter the compensation chamber 117 to be stored therein. This solves the problem of the conventional flat-plate evaporator that the flat-plate evaporator is placed horizontally so that the working fluid 2 of the compensation chamber is over-spaced from the evaporation face to cause dry burn.
The present invention mainly employs various materials in combination with each other as the materials of the respective sections of the loop heat pipe. Different materials are used with respect to different sections so that not only the total weight is reduced, but also the structural strength is increased. In addition, the present invention effectively provides heat conductivity or heat dissipation feature for the heat absorption section or heat dissipation section. Moreover, by means of the arrangement of the internal capillary structure 2, the compensation chamber 117 and the vapor passage 116, the shortcoming of the conventional loop heat pipe that the pressure impedance makes the liquid-phase working fluid 32 fail to flow back.
The present invention has been described with the above embodiments thereof and it is understood that many changes and modifications in such as the form or layout pattern or practicing step of the above embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.

Claims

What is claimed is:

1. A loop heat pipe structure comprising:

an evaporation chamber body having an upper case body and a lower board body, the upper case body and the lower board body together defining a closed chamber in which a capillary structure is disposed, the evaporation chamber body having an outlet and an inlet in communication with the closed chamber, a working fluid being filled in the closed chamber; and

a tube body having a first end, a second end and a middle section, the first and second ends being respectively positioned at two ends of the middle section, the first and second ends being respectively connected with the outlet and inlet of the evaporation chamber body, the upper case body, the lower board body and the tube body being made of different materials in combination with each other according to requirements, the materials being selected from a group consisting of titanium, stainless steel, copper, ceramic, aluminum, iron and graphite.

2. The loop heat pipe structure as claimed in claim 1, wherein a heat dissipation unit is disposed on outer side of the tube body, the heat dissipation unit being composed of multiple radiating fins or multiple cooling tube bodies.

3. The loop heat pipe structure as claimed in claim 1, wherein the closed chamber further has a compensation chamber and at least one vapor passage, one end of the vapor passage being in communication with the outlet.

4. The loop heat pipe structure as claimed in claim 3, wherein the vapor passage is selectively disposed on a wall face of the evaporation chamber body, which faces the capillary structure or disposed on one side of the capillary structure, which faces the evaporation chamber body, one end of the vapor passage being correspondingly connected with the outlet, the working fluid being converted between vapor phase and liquid phase, the vapor-phase working fluid and the liquid-phase working fluid being circulated within the entire interior of the loop heat pipe structure.

5. The loop heat pipe structure as claimed in claim 3, wherein the vapor passage is selectively disposed on a wall face of the evaporation chamber body, which faces the capillary structure or disposed on one side of the capillary structure, which faces the evaporation chamber body, one end of the vapor passage being correspondingly connected with the outlet, the working fluid being converted between vapor phase and liquid phase, the vapor-phase working fluid and the liquid-phase working fluid being circulated within the entire interior of the loop heat pipe structure.

6. The loop heat pipe structure as claimed in claim 3, wherein the outlet and the inlet are disposed on different sides of the evaporation chamber body, the second end of the tube body entering the closed chamber from the inlet of the evaporation chamber body and extending to one side distal from the compensation chamber.

7. The loop heat pipe structure as claimed in claim 3, wherein the evaporation chamber body is a flat-plate evaporation chamber body, the compensation chamber being correspondingly disposed in parallel to the capillary structure.

8. The loop heat pipe structure as claimed in claim 1, wherein the evaporation chamber body has a liquid passage, one end of the liquid passage being connected with the inlet, the liquid passage being disposed on one side of the capillary structure, the liquid passage and the vapor passage being respectively correspondingly disposed on upper and lower sides of the capillary structure.

9. The loop heat pipe structure as claimed in claim 1, wherein the capillary structure has multiple channels in adjacency to the lower board body, each channel having an open side and a closed side, the open side being attached to the lower board body, the open side having a width smaller than that of the closed side.

10. The loop heat pipe structure as claimed in claim 1, wherein the capillary structure is formed of sintered powder, the powder being selected from a group consisting of copper, aluminum, titanium and plastic fiber.