Heat pipe structure

Abstract

A heat pipe structure mainly includes a tubular housing with an inner surface where multiple grooves are formed, a working fluid contained in the tubular housing, and a wick sleeve unit located inside the tubular housing. The tubular housing defines an evaporation section, a condensation section, and an adiabatic section located between the evaporation section and the condensation section. The wick sleeve unit includes a first wick section disposed in the evaporation region and including a first main body and a rib inserted into any one of the grooves. A gap is formed between the rib and the inner surface for providing nucleation sites whereby the heterogeneous nucleation boiling is promoted and the heat-transferring efficiency is enhanced. Because of the gap, the capillary pressure are increased, and the wettability and the permeability are improved. Accordingly, the early dry-out phenomenon is retarded, and the heat-transferring efficiency of the heat pipe structure as a whole is efficiently increased.

Description

[Technical Field]

[0001] The present invention relates to a heat transfer device, and more particularly to a heat pipe structure having a sleeve unit. [Previous Technology]

[0002] A conventional heat pipe system is a heat transfer device consisting of a tubular body with a capillary structure and a working fluid inside. The tubular body extends axially and is divided into three sections: an evaporation section, an adiabatic section, and a condensation section. The capillary structure includes a plurality of axial grooves formed on the inner surface of the tubular body. When using this heat pipe, external heat enters the evaporation section, causing the working fluid to absorb heat and turn into vapor. Under the action of pressure difference, the vapor flows from the evaporation section through the adiabatic section and then enters the low-pressure, low-temperature condensation section. In the condensation section, the vapor condenses and releases latent heat. The released heat is discharged through an external heat dissipation device, and the condensed vapor turns into liquid. The liquid then flows back to the evaporation section by capillary action or gravity, completing the heat transfer process. The returned liquid is regarded as the working fluid for heat transfer again.

[0003] These axial grooves are the capillary structure of the tubular body, mainly pushing the liquid from the condensation section to the evaporation section through capillary action; however, these axial grooves all adopt the same size and shape in the evaporation section, the adiabatic section, and the condensation section, thus presenting a single homogeneous groove structure. However, this cannot ensure that all sections of the tubular body operate optimally, especially under certain extreme operating conditions, such as the capillary limit, entrainment limit, boiling limit, viscous limit, and sonic limit. Due to limitations such as flow rate and vapor transport, a single homogeneous trench structure may not be able to effectively promote the liquid to flow back to the evaporation section. It may even fail to meet the requirements of vapor flow, resulting in obstructed liquid flow and limited vapor transport, ultimately leading to dry-out or reduced heat transfer efficiency. In short, a single homogeneous capillary structure cannot solve all the above limitations at the same time, which relatively reduces the applicability of traditional heat pipes in high-efficiency applications. Overall, there is still room for improvement in traditional heat pipes. [Summary of the Invention]

[0004] Therefore, the purpose of this invention is to provide a heat pipe structure that mainly utilizes a core located in the evaporation section of the tubular shell within the sleeve unit to help improve the boiling and vaporization efficiency and liquid reflux rate of the evaporation section, thereby improving the heat conduction performance of the heat pipe structure.

[0005] Another object of the present invention is to provide a heat pipe structure, which mainly involves making the sleeve unit into multiple cores respectively disposed in different sections of the tubular shell, so as to conform to the size of the tubular shell and meet the heat transfer requirements of each section.

[0006] Therefore, the heat pipe structure of the present invention includes a hollow tubular shell, a working fluid disposed within the tubular shell, and a sleeve unit located inside the tubular shell. The tubular shell has an inner surface, a channel formed by the inner surface, and a plurality of grooves formed on the inner surface. The tubular shell system extends for a length to define an evaporation section, a condensation section, and an insulating section located between the evaporation section and the condensation section. A heating unit is provided outside the evaporation section. The working fluid is converted into vapor and forms a vapor flow. A heat dissipation unit is provided outside the condensation section to allow the vapor to condense into liquid and form a liquid flow, releasing heat. The aforementioned vapor flows in the channel and from the evaporation section to the condensation section, while the aforementioned liquid flows in the grooves and from the condensation section to the evaporation section. Furthermore, the sleeve unit includes a sub-core disposed in the evaporation section, and the sub-core has a first body and a rib system extending from the first body to... The rib protrudes outward and extends into any groove, thus creating a gap between the rib and the inner surface. This provides multiple nucleation sites to promote liquid boiling, while also enhancing capillary pressure, improving permeability and wettability, guiding the liquid to flow rapidly back into the evaporation section for heat conduction, thereby increasing heat transfer efficiency. Therefore, the application of this sleeve unit can optimize the internal structural design of the tubular shell, improve heat transfer efficiency and phase change stability, and is particularly suitable for thermal management applications in high heat flux environments; even more so... The sleeve unit can also be equipped with a second-zone sub-core located in the insulation section, or a third-zone sub-core located in the condensation section, or both second-zone and third-zone sub-cores can be added simultaneously. The geometry of the first-zone sub-core is different from that of the second-zone and third-zone sub-cores, so as to meet the thermal conductivity requirements of the operating environment of different sections, including the requirements for fluid reflux, vapor flow and heat transfer. It can also improve the liquid reflux efficiency and enhance the vapor flow transport capacity, thereby breaking through the operating limits of traditional heat pipes and improving the overall thermal conductivity of the heat pipe structure.

Implementation Method

[0007] The foregoing description and other technical contents, features and effects of the present invention will become clear from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

[0008] Referring to Figures 1 to 4, a first preferred embodiment of the heat pipe structure 3 of the present invention is shown. The heat pipe structure 3 includes a tubular shell 31, a working fluid 30 injected into the tubular shell 31, and a sleeve unit 32 located inside the tubular shell 31. The material of the tubular shell 31 is not limited and can be, but is not limited to, materials such as aluminum and copper. The material of the tubular shell 31 needs to be adjusted according to the type of working fluid 30. In this embodiment, the material of the tubular shell 31 is aluminum. The working fluid 30 is contained inside the tubular shell 31 and its type is not limited. It can be, but is not limited to, ammonia or other non-aqueous working fluids. In this embodiment, the working fluid 30 is ammonia.

[0009] Referring to Figures 1(a), 3, and 4, the tubular shell 31 is hollow. The tubular shell 31 is manufactured by an extrusion process. The interior of the tubular shell 31 has an inner surface 311, a channel 312 formed by the inner surface 311, and a plurality of grooves 313 formed on the inner surface 311. These grooves 313 are formed during the extrusion process and are formed on the inner surface 311. In this embodiment, the grooves 313 are, for example, recessed from the inner surface 311. Furthermore, the tubular shell 31 extends a length to divide the space into three sections. The sections are, in order, an evaporation section 31A, an insulation section 31B, and a condensation section 31C. The insulation section 31B is located between the evaporation section 31A and the condensation section 31C. The lengths of each of the sections 31A, 31B, and 31C can be adjusted as needed. Each groove 313 extends from the evaporation section 31A to the condensation section 31C. Furthermore, a heating unit 4 is provided outside the evaporation section 31A to heat the evaporation section 31A. The working fluid 30 is heated to the point of boiling and vaporization, meaning that the working fluid 30 absorbs the latent heat of vaporization in the evaporation section 31A and turns into steam. A heat dissipation unit 5 is provided on the outside of the condensation section 31C. This heat dissipation unit 5 can be a fan, a cooling head, or other suitable heat dissipation device; the figure only shows a fan as an example. The heat dissipation unit 5 facilitates the condensation process; when the steam condenses, it releases latent heat of vaporization, which is then transferred to the external environment through the heat dissipation unit 5. The vapor is allowed to condense into liquid in the condensation section 31C; the vapor flows in the channel 312 to form a vapor flow F1 (as shown by the dashed arrow in Figure 4), and flows from the evaporation section 31A through the adiabatic section 31B, and then into the condensation section 31C; the liquid flows in the grooves 313 to form a liquid flow F2 (as shown by the solid arrow in Figure 4), and flows from the condensation section 31C through the adiabatic section 31B, and then into the evaporation section 31A.

[0010] The sleeve unit 32 is located inside the tubular housing 31, and the sleeve unit 32 can be integrally formed with the tubular housing 31, which may include, but is not limited to, integral forming by 3D (three-dimensional) printing; or, the sleeve unit 32 and the tubular housing 31 can be separately formed, and in this case, separate forming is used as an example to illustrate all the figures of the present invention. In particular, the sleeve unit 32 can be a heterogeneous three-dimensional core tube structure as a three-dimensional refrigerant core, which may include, but is not limited to, being made by 3D (three-dimensional) printing, powder metallurgy, or other suitable methods. In this embodiment, 3D printing is used as an example, which helps to control the composition of the fine structure so that the sleeve unit 32 becomes a three-dimensionally printed refrigerant core tube. Regarding the formation of the heat pipe structure 3, the main steps are to first assess the thermal management constraints required for each section of the tubular shell 31, and then design the geometry of a sleeve unit 32 based on the constraints of each section. The sleeve unit 32 is then formed using 3D printing technology, and subsequently installed into the tubular shell 31. Finally, the working fluid 30 is introduced into the tubular shell 31. Through the 3D printing technology, the geometry of the sleeve unit 32 can be varied, thus customizing the three-dimensional refrigerant core design of the heat pipe structure 3 to meet the operating environment and thermal conductivity requirements of different sections of the tubular shell 31.

[0011] In addition, the sleeve unit 32 includes a sub-core 321, which extends for a length and is disposed in the evaporation section 31A. The extension length of the sub-core 321 can correspond to the length of the evaporation section 31A. The sub-core 321 has a first body 3211 and at least one rib 3212. That is, the number of ribs 3212 can be one or more (more than one). In particular, the distribution and number of ribs 3212 can be adjusted according to the heating area or heating density. In this embodiment, multiple ribs 3212 are used as an example. In addition, the rib 3212 can be formed into a three-dimensional structure, and the geometry of the rib 3212 can be appropriately varied to match the shape of the groove 313. For example, each rib 3212 can be a continuous rib shape (as shown in the figure). As shown in Figure 1(a), or the rib 3212 may be composed of a plurality of spaced columns 3212a to form an intermittent rib shape (as shown in Figure 2), which is beneficial for achieving uniform wetting and enhancing permeability. Furthermore, the rib 3212 protrudes outward from the first body 3211 and extends into any of the grooves 313. When there are a plurality of ribs 3212, the ribs 3212 may protrude radially from the first body 3211 and extend into the grooves 313 respectively. When each rib 3212 extends into each groove 313, a gap S1 is left between the rib 3212 and the inner surface 311. That is, the extension of the rib 3212 helps to provide a plurality of nucleation sites NS to promote boiling and can also enhance capillary pressure to assist liquid reflux.

[0012] Referring to Figures 1 to 4, when using the heat pipe structure 3, the heating unit 4 is used to heat the evaporation section 31A to promote the boiling and vaporization of the working fluid 30. That is, the heating operation of the heating unit 4 causes the working fluid 30 (e.g., liquid ammonia) to absorb the latent heat of vaporization and produce a phase change. At this time, since the ribs 3212 of the sub-core 321 extend into the grooves 313, the gap S1 can provide multiple nucleation sites NS (see Figure 6(a)) to promote heterogeneous nucleation boiling. This enhances the formation and release of boiling bubbles. In addition, the three-dimensional structure of the rib 3212 or the columns 3212a provide permeability, which not only allows the evaporation section 31A to maintain uniform wetting, but also causes surface roughening, which can increase the nucleation sites NS to help endothermic effect, promote heterogeneous nucleation boiling, and thus improve phase change efficiency. As a result, the working fluid 30 is converted into vapor. Due to the generation of vapor, the pressure of the evaporation section 31A is higher than the pressure of the condensation section 31C, which creates a pressure difference inside the tubular shell 31. This pressure difference drives the vapor to flow in the channel 312 and towards the condensation section 31C, thus forming a vapor flow F1 (see Figure 5, which is only shown in a simplified manner).

[0013] When the vapor flows into the condensation section 31C, because the condensation section 31C is a low-pressure and low-temperature environment, this environment will cause the vapor to condense into a liquid, and release latent heat of vaporization during the condensation process. The heat released by the latent heat passes through the sleeve unit 32 and the tubular shell 31 to be transferred to the heat dissipation unit 5, and then the heat dissipation unit 5 releases the heat outward (see the thick black arrow in Figure 4), thus achieving heat dissipation. The rejection effect is as follows: As for the liquid obtained by condensation, the presence of the grooves 313 will cause capillary action, which will push the liquid to flow stably in the grooves 313 and flow towards the evaporation section 31A that continuously consumes liquid, thus forming a liquid flow F2 (see Figure 5, which is only shown in a simplified manner); When the liquid flows back to the evaporation section 31A, the gap S1 between each rib 3212 and the inner surface 311 is smaller than the width W1 of the groove 313, which can enhance the capillary pressure (as shown in Figure 6(b)). The resulting capillary action guides the liquid to flow back to the evaporation section 31A quickly, thus completing the heat transfer operation; The liquid flowing back to the evaporation section 31A is then used as the aforementioned working fluid 30 to perform heat transfer operation again.

[0014] Therefore, the outwardly protruding ribs 3212 of the sub-core 321 can help form boiling bubbles, thereby improving heat input and increasing the thermal conductivity of the evaporation section 31A, as well as increasing wettability and promoting capillary action; furthermore, the capillary action generated by the sub-core 321 also causes the liquid to flow back to the evaporation section 31A quickly, ensuring that there is enough working fluid 30 in the evaporation section 31A to continue to absorb heat and evaporate. This not only delays the drying process, but also facilitates the implementation of subsequent condensation operations. Thus, under the cycle of heat absorption, condensation, and liquid reflux, the overall thermal conductivity of the heat pipe structure 3 is effectively improved, resulting in excellent heat transfer performance.

[0015] Referring to Table 1, a comparison is made between the average thermal conductivity (Average Keff value) of a general heat pipe (without the sleeve unit 32) and the heat pipe structure 3 of the present invention (with the sleeve unit 32). It can be seen that the present invention utilizes the sleeve unit 32 installed in the tubular shell 31 to effectively improve the thermal conductivity of the heat pipe structure 3.

[0016] Table 1 Heat pipe name Average thermal conductivity - Avg. Keff (kW / mK) EWJ Regular HP [Unsheathed Unit] 126 HP with wick sleeve [with sleeve unit] 163.1

[0017] In a second preferred embodiment of the heat pipe structure 3 of the present invention, the heat pipe structure 3 still includes a tubular shell 31 having three sections 31A, 31B, and 31C, a sleeve unit 32 having a single-section core 321, and a working fluid 30; particularly, the sleeve unit 32 further includes a single-section core 322, so that the single-section core 321 and the single-section core 322 coexist within the tubular shell 31 (as shown in FIG. 8); or, the sleeve unit 32 further includes a triple-section core 323, so that the single-section core 321 and the triple-section core 323 coexist within the tubular shell 31 (as shown in FIG. 7); or, the The sleeve unit 32 also includes a first and second zone sub-core 322 and a third zone sub-core 323, so that the first zone sub-core 321, the second zone sub-core 322 and the third zone sub-core 323 exist simultaneously in the tubular housing 31 (as shown in Figure 9). The addition of the second zone sub-core 322 and the third zone sub-core 323 can be determined mainly based on the size of the heat dissipation area and the flow field state of the vapor flow F1 and the liquid flow F2. Therefore, the sleeve unit 32 is used to enhance the operating performance of a specific section or multiple sections. Here, we only use the example of the sleeve unit 32 including the first zone sub-core 321, the second zone sub-core 322 and the third zone sub-core 323 to illustrate the following implementation operation.

[0018] In addition, the first-zone sub-core 321, the second-zone sub-core 322, and the third-zone sub-core 323 are respectively located in the evaporation section 31A, the insulation section 31B, and the condensation section 31C, and the geometric structures of the sub-cores 321, 322, and 323 are different from each other. That is, as mentioned above, the first-zone sub-core 321 has the aforementioned first body 3211 and one or more ribs 3212 to present a radially outward protruding structure, while the second-zone sub-core 322 has a second body 3221 surrounded by the inner surface 311 (as shown in FIG. 10), and the second body 3221 may preferably have a plurality of barrier meshes 3221a to form a grid structure (as illustrated in FIG. 8(b) and FIG. 9(b)). Therefore, the second body 3221 can define the paths of liquid flow and vapor flow respectively, thereby reducing the influence of vapor entrainment on the liquid and ensuring that the liquid flows back to the evaporation section 31A along the groove walls of the grooves 313, thereby improving the stability of fluid return. At the same time, the second body 3221 can also serve as a barrier to separate the liquid flow F2 and the vapor flow F1 (as shown in Figure 13), that is, to prevent vapor and liquid from colliding with each other in the tubular shell 31 and thus affecting the circulation efficiency.

[0019] Referring to Figures 9(c) and 11, the three-zone sub-core 323 located in the condensation section 31C is defined as a vapor capture and diversion element. That is, the three-zone sub-core 323 has a third body 3231 surrounded by the inner surface 311 and a condensation rib 3232 connected to the third body 3231. The condensation rib 3232 extends toward the channel 312. Furthermore, the condensation rib 3232 preferably includes a part penetrating through the third body 3231. The absence of one flow guide rib 3232a and multiple branches 3232b extending inward from the flow guide rib 3232a allows the condensation rib 3232 to provide a tree-like branching structure. These branches 3232b extend into the channel 312 to form an inwardly extending configuration. The flow guide rib 3232a may or may not extend into the groove 313. Here, it is an example that the flow guide rib 3232a extends into the groove 313, which helps to guide the condensed liquid along the branches 3232b to collect at the flow guide rib 3232a and then flow back to the groove 313. Therefore, the three-zone core 323 can capture passing vapor and enhance the condensation and liquid formation effects, so that the condensation section 31C can form a stable liquid return channel to improve the circulation efficiency of the heat pipe structure 3. The implementation of the second preferred embodiment is illustrated below using this tree-like branching structure as an example.

[0020] Referring to Figure 12, when using the heat pipe structure 3, the process by which the working fluid 30 in the evaporation section 31A boils and vaporizes to form a vapor flow F1 due to heating can be referred to the aforementioned related description. When the vapor flows into the condensation section 31C, the aforementioned tree-like branch structure of the three-zone core 323 can increase the surface area to capture the vapor and assist in increasing the formation of condensation nuclei, thus promoting the condensation of the vapor. The tree-like branch structure further forms a capillary path to guide the liquid generated by the condensation into the grooves 313, while simultaneously generating capillary action to promote the backflow of the liquid, so that the liquid flows stably in the grooves 313 and flows in the direction of the evaporation section 31A, thus forming a liquid flow F2 (refer to Figure 14, only shown in a simplified manner).

[0021] The adiabatic section 31B is a transport area located between the evaporation section 31A and the condensation section 31C. In the adiabatic section 31B, the second body 3221 can separate the vapor flow F1 from the liquid flow F2 to reduce the impact of vapor disturbance on liquid backflow (see Figure 13, only schematically shown). This can reduce the occurrence of entrainment at the gas-liquid interface, thereby reducing the liquid backflow into the evaporation section 31A. The loss of liquid and the dry-out phenomenon caused by insufficient liquid are delayed, while the rate of liquid return is increased. Therefore, the second body 3221 helps to stabilize the flow of the vapor flow F1 and the liquid flow F2. During the process of the liquid flowing back to the evaporation section 31A, the gap S1 between each rib 3212 and the inner surface 311 can enhance the capillary pressure. The resulting capillary action quickly guides the liquid back to the evaporation section 31A to be used as the aforementioned working fluid 30 again for heat transfer operations.

[0022] Accordingly, the different sub-cores 321, 322, and 323 of the sleeve unit 32 can meet the functional requirements and thermal conductivity requirements of different sections 31A, 31B, and 31C of the tubular shell 31. In particular, the outwardly protruding ribs 3212 of the sub-core 321 are a structure that can help form boiling bubbles without hindering the expansion and release of boiling bubbles. That is, the protrusion of the ribs 3212 can promote heterogeneous nucleation and increase the probability of boiling bubble formation, while avoiding obstruction to the expansion and release of boiling bubbles. Therefore, it can reduce the thermal resistance, and at the same time, it can help maintain the liquid film coverage, thereby promoting the reflux of the liquid, and also help increase the wettability and promote capillary action to delay drying. Furthermore, the second body 3221 of the second-zone sub-core 322 separates the vapor flow F1 and the liquid flow F2, which flow in opposite directions, to reduce the occurrence of entanglement. As for the combination of the third body 3231 and the condensation ribs 3232 of the third-zone sub-core 323, it is a structure that does not obstruct the return of the liquid to the evaporation section. It mainly helps to form condensation nuclei to facilitate the condensation of vapor into liquid and guides the liquid to quickly enter the grooves 313 to achieve stable fluid circulation. It can also assist in the effective removal of heat. In summary, the geometric configuration of the sleeve unit 32 can be customized according to the size of the tubular shell 31 and the heat transfer requirements, thereby improving the heat conduction performance of the heat pipe structure 3.

[0023] In summary, the heat pipe structure of the present invention mainly consists of a core section within a tubular shell having multiple grooves and divided into multiple sections. This core section helps to improve the boiling and vaporization efficiency and liquid reflux rate of the evaporation section, thereby delaying drying. Alternatively, two core sections can be added to separate the vapor and liquid flows flowing in opposite directions, thereby reducing entanglement. Or, three core sections can be added to assist in capturing vapor and promoting condensation and stabilizing liquid circulation. Therefore, the use of this shell unit helps to improve the heat transfer efficiency of the heat pipe structure. Furthermore, the geometry of the shell unit can be changed according to the needs of any section to achieve customized applications that meet the requirements of different sections, thus effectively achieving the purpose of the present invention.

[0024] However, the above description is only for illustrating preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the specification of the present invention should still fall within the scope of the patent of the present invention. [Simplified Explanation of the Diagram]

[0025] Figure 1 is a structural schematic diagram of the first preferred embodiment of the present invention. Figure 1(a) is a partial enlarged cross-sectional view of segment AA shown in Figure 1. Figure 1(b) is a partial enlarged cross-sectional view of segment BB shown in Figure 1. Figure 1(c) is a partial enlarged cross-sectional view of segment CC shown in Figure 1. Figure 2 is a schematic diagram of another variation of Figure 1(a). Figure 3 is a schematic diagram of the end face of Figure 1(a). Figure 4 is a schematic diagram of the overall implementation state of the first preferred embodiment. Figure 5 is a simplified partial structural schematic diagram of the first preferred embodiment in its implementation state. Figures 6(a) and 6(b) are schematic diagrams of the first preferred embodiment in its implementation state. Figure 7 is a structural schematic diagram of one of the second preferred embodiments of the present invention. Figure 7(a) is a partial enlarged cross-sectional view of segment AA shown in Figure 7. Figure 7(b) is a partial enlarged cross-sectional view of segment BB shown in Figure 7. Figure 7(c) is a partial enlarged cross-sectional view of segment CC shown in Figure 7. Figure 8 is another structural schematic diagram of the second preferred embodiment of the present invention. Figure 8(a) is a partially enlarged cross-sectional view of segment AA shown in Figure 8. Figure 8(b) is a partially enlarged cross-sectional view of segment BB shown in Figure 8. Figure 8(c) is a partially enlarged cross-sectional view of segment CC shown in Figure 8. Figure 9 is a further structural schematic diagram of the second preferred embodiment of the present invention. Figure 9(a) is a partially enlarged cross-sectional view of segment AA shown in Figure 9. Figure 9(b) is a partially enlarged cross-sectional view of segment BB shown in Figure 9. Figure 9(c) is a partially enlarged cross-sectional view of segment CC shown in Figure 9. Figure 10 is an end view of Figures 8(b) and 9(b). Figure 11 is an end view of Figures 7(c) and 9(c). Figure 12 is a schematic diagram of the overall implementation state of Figure 9. Figure 13 is a schematic diagram of Figures 8(b) and 9(b) in the implementation state. Figure 14 is a schematic diagram of Figures 7(c) and 9(c) in the implementation state.

Claims

1. A heat pipe structure comprising a hollow tubular shell and a working fluid disposed within the tubular shell, wherein, The tubular shell has an inner surface, a channel formed by the inner surface, and a plurality of grooves formed on the inner surface. The tubular shell extends for a length to define three sections: an evaporation section, a condensation section, and an adiabatic section located between the evaporation section and the condensation section. Each groove extends from the evaporation section to the condensation section. A heating unit is provided outside the evaporation section to convert the working fluid into vapor through heating. The vapor flows in the channel to form a vapor stream and flows from the evaporation section to the condensation section. A heat dissipation unit is provided outside the condensation section to dissipate the latent heat released during the condensation of the vapor. The vapor condenses into liquid in the condensation section, and the liquid flows in the grooves to form a liquid stream and flows from the condensation section to the evaporation section. The characteristic feature is that: The heat pipe structure also includes a sleeve unit located inside the tubular shell. The sleeve unit is manufactured by a non-vacuum sintering method, and the working fluid is ammonia or other non-aqueous fluid. The sleeve unit includes a sub-core located in the evaporation section. The sub-core has a first body and at least one rib. The rib protrudes outward from the first body and extends into any of the grooves. The rib does not contact the inner surface of the tubular shell. Therefore, when the rib extends into the groove, a gap is left between the rib and the inner surface to promote heterogeneous nucleation and boiling, and to increase capillary pressure to promote the liquid reflux to the evaporation section, thereby enhancing the heat transfer efficiency of the heat pipe structure.

2. The heat pipe structure according to claim 1, wherein, The sub-core has a plurality of ribs, which extend into the grooves respectively.

3. The heat pipe structure according to claim 1, wherein, The rib has multiple spaced columns.

4. The heat pipe structure according to claim 1, wherein, The sleeve unit is a three-dimensional refrigerant wick.

5. The heat pipe structure according to claim 1, wherein, The sleeve unit is manufactured by 3D printing or powder metallurgy.

6. The heat pipe structure according to claim 1, wherein, The sleeve unit further includes a three-zone sub-core disposed in the condensation section, and the three-zone sub-core is defined as a vapor capture and guide element and includes a third body surrounded by the inner surface and a condensation rib extending into the channel, thereby capturing the vapor and guiding the liquid into the groove.

7. The heat pipe structure according to claim 6, wherein, The condensation rib has at least one drainage rib penetrating the third body, and a plurality of branches extending inward from the drainage rib, the branches extending into the channel.

8. The heat pipe structure according to claim 1, wherein, The sleeve unit further includes a second sub-core disposed in the insulation section, and the second sub-core has a second body surrounded by the inner surface, thereby separating the liquid flow and the vapor flow.

9. The heat pipe structure according to claim 8, wherein, The second body has multiple barrier nets.

Images