Heat pipes including composite wick structures and related manufacturing methods

Abstract

Heat pipes and methods for forming such heat pipes are described, including those for use in nuclear reactor systems. A typical method for forming a heat pipe includes forming a first wick structure from a first material and forming a second wick structure on the first wick structure. Forming the second wick structure may include mixing a second material and a third material, and heating the mixture of the second and third materials to a temperature (a) below the melting temperature of the second material and (b) above the melting temperature of the third material to melt the third material. The method may further include cooling the mixture of the second and third materials below the melting temperature of the third material, such that the third material solidifies to bond multiple particles of the second material into a porous structure.

Description

Technical Field

[0003]

[0001] This technology relates to a method and apparatus for forming heat pipe components such as heat pipes and composite wicks used in power conversion systems such as nuclear reactor power conversion systems.

[0002] (Cross - reference to related applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 066,515, entitled "MATERIAL COMPOSITION TO ENABLE THREE - DIMENSIONAL(3D)PRINTING OF A COMPOSITE HEAT PIPE WICK", filed on August 17, 2020, which is hereby incorporated by reference in its entirety.

Background Art

[0003] A heat pipe is a heat transfer device that combines the principles of both thermal conductivity and phase transition to effectively transfer heat between two interfaces. More specifically, a heat pipe is a closed container that houses a working fluid and includes an evaporator region located at a high - temperature interface and a condenser region located at a low - temperature interface. The high - temperature interface heats and evaporates / vaporizes the working fluid in the evaporator region. Due to the pressure difference between the high - temperature evaporator region and the lower - temperature condenser region, the evaporated / vaporized working fluid flows through the heat pipe from the evaporator region towards the condenser region, where the working fluid is cooled and condensed, releasing latent heat to the low - temperature interface. Thereafter, the condensed / cooled working fluid is returned to the evaporator region via capillary action, centrifugal force, gravity, and / or other forces acting against the pressure difference. For example, a heat pipe may include a wick for transporting the working fluid via capillary action.

[0004] Due to their very high heat transfer coefficients for evaporation and condensation, heat pipes are highly effective heat conductors. Therefore, heat pipes can be used to remove heat from power plants, such as the core of a nuclear reactor. Heat pipes can also be used to remove / transport heat in spacecraft, computer systems, and other applications where highly efficient heat transfer is desired. [Overview of the project]

[0005] Aspects of this disclosure generally relate to heat pipes and methods for manufacturing heat pipes used in nuclear reactor systems and the like. In some embodiments described below, a typical method for manufacturing a heat pipe includes forming a first wick structure from a first material and forming a second wick structure on the first wick structure. The first and second wick structures may form a monolithic structure together. Forming the second wick structure may include mixing a second material and a third material, and heating the mixture of the second and third materials to a temperature (i) below the melting temperature of the second material and (b) above the melting temperature of the third material to melt the third material. This method may further include cooling the mixture of the second and third materials to below the melting temperature of the third material so that the third material solidifies to bind together multiple particles of the second material to form a porous structure.

[0006] In some embodiments, forming the first and second wick structures may include forming the wick structures via one or more three-dimensional (3D) additive manufacturing processes, such as one or more laser-directed energy deposition (DED) additive manufacturing processes. For example, forming the first wick structure may include irradiating a metal wire of the first material with a laser to melt the first material. Similarly, forming the second wick structure may include irradiating a mixture of powder of the second material and powder of the first material with a laser to melt the third material without melting the second material, thereby mixing the melted third material with the second material. In some embodiments, the first and third materials may be metallic materials (e.g., including molybdenum), and the second material may be a non-metallic material (e.g., a ceramic material).

[0007] In some embodiments, the first material is impermeable to fluid, and forming the first wick structure may include forming at least one flow path defined by the first material. The at least one flow path may be configured (e.g., dimensioned and molded) to pump a fluid (e.g., a two-phase working fluid) against a pressure difference in the heat pipe. In other embodiments, the first material may be a porous material defining one or more flow paths. Similarly, the second porous structure may also be configured to pump a fluid against a pressure difference in the heat pipe. The porous structure of the second wick structure may have finer porosity, allowing for localized fluid flow against larger pressure differences than the first wick structure. Thus, the first and second wick structures can be combined to form a composite wick structure. [Brief explanation of the drawing]

[0008] Many aspects of this technology can be better understood by referring to the following drawings. The elements of the drawings do not necessarily adhere to a scale ratio. Instead, the emphasis is on clearly illustrating the principles of this technology.

[0009] [Figure 1A]This is a longitudinal cross-sectional view of a heat pipe configured according to an embodiment of this technology. [Figure 1B] This is an isometric cross-sectional view of a heat pipe configured according to an embodiment of this technology.

[0010] [Figure 2] This is an enlarged cross-sectional view of the interface between a portion of the first wick of the heat pipe shown in Figures 1A and 1B and a portion of the second wick of the heat pipe shown in Figures 1A and 1B, according to an embodiment of the present technology.

[0011] [Figure 3] Figures 3A-3C are cross-sectional views of the heat pipes shown in Figures 1A and 1B, illustrating various steps in a method for manufacturing a heat pipe according to an embodiment of this technology.

[0012] [Figure 4] Figures 4A and 4B are cross-sectional side views of an additive manufacturing system that may be used in a method for forming the heat pipe shown in Figures 3A-3C according to an embodiment of the present technology.

[0013] [Figure 5] Figures 1A and 1B show a partial schematic side cross-sectional view of a reactor system including multiple heat pipes, according to an embodiment of the present technology. [Modes for carrying out the invention]

[0014] To fully understand the various embodiments of this technology, specific details are shown in the following description and Figures 1-5. In other examples, well-known structures, materials, operations, and / or systems, often related to nuclear reactors, heat pipes, heat exchangers, additive manufacturing processes, etc., are not shown in detail or described in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. However, those skilled in the art will recognize that this technology can be implemented without one or more of the details described herein, and / or with other structures, methods, components, etc.

[0015] The terms used herein should be interpreted in the broadest and most reasonable way, even when used in conjunction with the detailed description of specific examples of embodiments of this technology. In fact, certain terms may be emphasized below. However, terms intended to be interpreted in a limited way are explicitly and specifically defined in the sections of this detailed description.

[0016] The accompanying drawings illustrate embodiments of the present technology and are not intended to limit its scope unless explicitly stated otherwise. The sizes of the various elements depicted are not necessarily drawn to scale, and these elements may be enlarged for improved readability. Details of components may be abstracted in the drawings so as not to be necessary for a complete understanding of how the present technology is constructed and used, such as the location of components and specific precise connections between components. Many of the details, dimensions, angles, and other features shown in the drawings are merely illustrative of a particular embodiment of the present disclosure. Other embodiments may have other details, dimensions, angles, and features without departing from the present technology. Furthermore, those skilled in the art will understand that further embodiments of the present technology may be carried out without some of the details described below.

[0017] Figures 1A and 1B are longitudinal and isometric cross-sectional views, respectively, of a heat pipe 100 configured according to an embodiment of the present technology. Referring together to Figures 1A and 1B, the heat pipe 100 includes an outer wall or casing 102 having an outer surface 103a and an inner surface 103b, defining a channel 104 (e.g., cavity, chamber). The heat pipe 100 contains a working fluid (not shown) contained within the channel 104. The working fluid may be a two-phase (e.g., liquid and gas phase) material such as lithium, sodium, and / or potassium. The casing 102 may be formed from any material with suitable strength and thermal conductivity, such as one or more metal or ceramic materials. In some embodiments, as described later with respect to Figure 5, the heat pipe 100 may be used in a nuclear reactor system. In such embodiments, the casing 102 may be formed from a material with suitable strength and thermal conductivity and neutron resistance. In some embodiments, the casing 102 may be formed from steel, molybdenum, molybdenum alloy, molybdenum oxide-lanthanum, and / or other metallic materials. In the illustrated embodiments, the casing 102 has a substantially square cross-sectional shape, but in other embodiments, the casing 102 may have a circular, rectangular, polygonal, irregular, or other cross-sectional shape.

[0018] In the illustrated embodiments, the heat pipe 100 further includes a first wick 110 extending along / on a portion of the inner surface 103b, such as the lower / floor portion of the inner surface 103b (for example, against gravity). The heat pipe 100 may further include a second wick 120 extending along / on the entirety or portion of the remaining portion of the inner surface 103b and the first wick 110. In some embodiments, as shown in Figure 1B, the first wick 110 may define one or more channels 114 (for example, including individually identified first channels 114a and second channels 114b). The first wick 110 and the second wick 120 may also be referred to as porous structures, meshes, wick structures, etc.

[0019] Referring to Figure 1A, the heat pipe 100 includes an evaporator region 130 at / near its first end, a condenser region 132 at / near its second end, and an adiabatic region 134 extending between the evaporator region 130 and the condenser region 132. The evaporator region 130 may be positioned to receive heat from a heat source, such as a reactor system or an electronic system or component. During operation, the heat absorbed in the evaporator region 130 evaporates (e.g., vaporizes) the working fluid within the evaporator region, creating a pressure difference between the evaporator region 130 and the condenser region 132. This pressure difference drives the evaporated working fluid from the evaporator region 130 through the adiabatic region 134 to the condenser region 132. The working fluid cools and condenses in the condenser region 132, transferring heat to the casing 102 and moving out of the heat pipe 100. Referring again to Figures 1A and 1B, the first wick 110 and the second wick 120 are configured to transport the working fluid, which has been condensed / cooled against the pressure gradient in the heat pipe 100, from the condenser region 132 to the evaporator region 130, where the working fluid can be heated and evaporated again. Thus, in some embodiments, heat is accumulated in the evaporator region 130 and removed from the condenser region 132, with no heat removed or added to the adiabatic region 134.

[0020] In some embodiments, the first wick 110 is a coarse wick that allows for relatively high throughput of the working fluid compared to the second wick 120. In some embodiments, the second wick 120 is a fine wick configured to pump the working fluid over a shorter distance than the first wick 110 but over a larger pressure gradient than the first wick 110. Thus, the first wick 110 and the second wick 120 may form a composite / synthetic wick, where (i) the first wick 110 allows for long-distance flow of the working fluid, and (ii) the second wick 120 allows for localized flow of the working fluid. In other embodiments, the heat pipe 100 may include other composite wick arrangements to facilitate the flow of working fluid through the channel 104 of the heat pipe 100.

[0021] Figure 2 is an enlarged cross-sectional view of the interface between a portion of the first wick 110 and a portion of the second wick 120 of a heat pipe 100 according to an embodiment of the present technology. In the illustrated embodiment, the first wick 110 is formed from a material that is relatively impermeable to the fluid (e.g., working fluid). Referring further to Figures 1A and 1B, in some embodiments, the first wick 110 may be formed from the same material as the casing 102 (e.g., steel, molybdenum, molybdenum alloy, molybdenum oxide-lanthanum, and / or other metallic materials) and / or may be formed integrally / monolithically with the casing 102. In other embodiments, the first wick 110 may be formed from a porous material that contains / can define a smaller hydraulic space than the second wick (e.g., the first wick 110 may be a coarse wick).

[0022] The second wick 120 may be formed from a mixture of materials comprising at least the first material 222 and the second material 224. The second material 224 may have a higher melting temperature than the first material 222. In the illustrated embodiments, the second material 224 comprises a plurality of discrete particles, which are bonded together by the first material 222 to form a porous structure or mesh comprising a plurality of pores 226 (e.g., openings, channels, pockets). In some embodiments, the first material 222 may form a thin film around the second material 224 (e.g., its individual particles) such that the pores 226 define / fill most of the space within the second wick 120 between the particles of the second material 224. The plurality of pores 226 together provide a channel for the working fluid to pass through the second wick 120. In some embodiments, the first wick 110 and the second wick 120 may be formed integrally / monolithically so that they integrally form a monolithic structure. In some embodiments, the first wick 110 and the second wick 120 may be formed from the same material (e.g., the second material 224) so ​​that they provide an integral porous structure or mesh that provides a flow path for the working fluid.

[0023] Figures 3A-3C are cross-sectional views of a heat pipe 100 showing various stages in a method of manufacturing the heat pipe 100 according to an embodiment of the present technology. Figures 4A and 4B are cross-sectional views of a layered manufacturing system 440 (the "system 440") that can be used in the method of manufacturing the heat pipe 100 shown in Figures 3A-3C according to an embodiment of the present technology. Some features of the method of Figures 3A-3C are described in the context of the system 440 shown in Figures 4A and 4B for purposes of explanation, but those skilled in the art will readily understand that the method can be carried out using other suitable systems and / or devices (e.g., other layered manufacturing systems and / or 3D printing systems).

[0024] FIG. 3A shows the heat pipe 100 after forming the casing 102, and FIG. 3B shows the heat pipe 100 after forming the first wick 110. In some embodiments, the casing 102 and the first wick 110 may be formed using the same manufacturing process and / or may be integrally formed to provide an integral / monolithic structure. Referring further to FIG. 4A, for example, the system 440 may be a laser metal directed energy deposition (DED) system configured to melt a metal material 442, such as a metal wire, to form the casing 102 and the first wick 110. In some embodiments, the system 440 may be used to form the casing 102 and the first wick 110 via a metal wire printing method. More specifically, the system 440 may include a laser source 444 configured to irradiate a laser 445 onto the metal material 442 disposed on a substrate 441. The substrate 441 may be a substrate separate from the heat pipe 100 or may be a previously formed layer of the heat pipe 100 (e.g., a lower layer on which the heat pipe 100 is vertically additive manufactured). The laser source 444 is configured to move relative to the substrate 441 and the metal material 442, whereby the laser 445 sequentially melts the metal material 442 to form a weld pool 443, which then cools and solidifies to form part of the casing 102 and the first wick 110. In some embodiments, the system 440 may be configured to supply a gas (e.g., an inert gas) towards the weld pool 443 to control various parameters of the manufacturing process.

[0025] Figure 3C shows the heat pipe 100 after the second wick 120 has been formed. In some embodiments, the second wick 120 is formed directly on the casing 102 and the first wick 110 (e.g., printed there / on it) so that the heat pipe 100 is a single / monolithic structure. Referring further to Figure 4B, the system 440 may further include a first material source 446 (e.g., a nozzle) configured to direct the first material 222 toward the laser 445, and a second material source 448 (e.g., a nozzle) configured to direct the second material 224 toward the laser 445. Referring together to Figures 2 and 4B, the first material 222 may have a melting temperature selected such that the first material 222 melts when exposed to the laser 445, while the second material 224 may have a melting temperature selected such that the second material 224 does not melt when exposed to the laser 445. Therefore, the first material 222 and the second material 224 can be combined in a welding pool 449 containing a mixture of molten first material 222 and second material 224 discrete solid (e.g., unmelted) particles. After heating, the welding pool 449 may then be cooled and solidified to form part of the second wick 120. More specifically, the molten first material 222 may be cooled and solidified to bond the discrete solid (e.g., unmelted) particles of the second material 224 together, thereby forming a porous second wick 120 containing pores 226.

[0026] In some embodiments, the first material 222 may be supplied from a first material source 446 as a powder, such as steel, molybdenum, and / or other metallic material powder. Similarly, the second material 224 may be supplied from a second material source 448 as a powder. In some embodiments, the second material 224 includes non-metallic materials such as ceramic materials, graphite, zirconium carbide, titanium carbide, and / or other carbide materials. Thus, in some aspects of the art, the system 440 may supply the first material 222 and the second material 224 as a mixture of two powders, one metal and the other ceramic, such that when heated by the laser 445, the metal powder melts and the ceramic particles bond to the porous structure of the second wick 120. In other embodiments, the second material 224 may, alternatively or additionally, include a metallic material having a sufficiently high melting temperature so as not to melt when exposed to the laser 445 during manufacturing. Therefore, in some aspects of the present technology, the system 440 may supply the first material 222 and the second material 224 as a mixture of two metal powders such that when heated by the laser 445, only the metal powder of the first material 222 melts and bonds the metal particles of the second material 224 to the porous structure of the second wick 120.

[0027] In other embodiments, the system 440 may supply the first material 222 and the second material 224 in other ways. For example, the first material 222 and the second material 224 may be supplied as separate powders via the same material source (e.g., a nozzle). In some embodiments, instead of being supplied as separate powders or mixtures, the first material 222 may be pre-coated with the second material 224, and during manufacturing, the laser 445 may melt the coating of the first material 222 from the second material 224. Thus, in some aspects of the art, the system 440 may supply the first material 222 and the second material 224 as metal-coated non-metallic (e.g., ceramic) powders such that when heated by the laser 445, the metal melts and binds the non-metallic particles together to form a porous structure of the second wick 120.

[0028] Continuing to refer to Figures 2 and 4B together, a very fine porous structure can be generated by melting the first material 222 and binding the discrete particles of the second material 224. In some aspects of this technology, the fine porosity of the second wick 120 may enable it to pump the working fluid against a larger pressure gradient than a porous structure with coarser porosity. In particular, conventional manufacturing processes such as machining and casting cannot produce a composite heat pipe 100 containing a monolithically formed first wick 110 and second wick 120 with different porosities.

[0029] In some embodiments, the heat pipe 100, described in detail with reference to Figures 1A-4B, may be used to remove heat from power plant systems such as nuclear reactor systems. In some embodiments, the heat pipe 100 may be used in either of the nuclear reactor systems described in detail in (i) U.S. Patent Application No. 17 / 071,838, filed October 15, 2020, entitled “HEAT PIPE NETWORKS FOR HEAT REMOVAL, SUCH AS HEAT REMOVAL FROM NUCLEAR REACTORS, AND ASSOCIATED SYSTEMS AND METHODS,” and / or (ii) U.S. Patent Application No. 17 / 071,795, filed October 15, 2020, entitled “NUCLEAR REACTORS HAVING LIQUID METAL ALLOY FUELS AND / OR MODERATORS,” which are incorporated herein by reference in their entirety.

[0030] For example, Figure 5 is a partial schematic side cross-sectional view of a reactor system 550 ("System 550") including a plurality of heat pipes 100 configured according to an embodiment of the present technology. In the illustrated embodiment, System 550 includes a reactor vessel 552 and a radiation shielding vessel 554 surrounding / enclosing the reactor vessel 552. In some embodiments, the reactor vessel 552 and the radiation shielding vessel 554 may be substantially cylindrical or capsule-shaped. System 550 further includes a plurality of layers of heat pipes 100 within the reactor vessel 552. Each layer may include one or more heat pipes 100 (e.g., an array of heat pipes 100). In the illustrated embodiment, the heat pipes 100 are spaced apart from each other and stacked on top of each other. In some embodiments, the heat pipes 100 may be attached / fixed to a common frame 559, a part of the reactor vessel 552 (e.g., its walls), and / or other suitable structures within the reactor vessel 552. In other embodiments, the heat pipes 100 may be stacked directly on top of each other such that each heat pipe 100 supports and / or is supported by one or more other heat pipes 100.

[0031] In the illustrated embodiment, the system 550 further includes a shield or reflector region 564 that at least partially encloses the core region 566. The heat pipe 100 may be circular, linear, polygonal, and / or have other shapes, such that the core region 566 has a corresponding three-dimensional shape (e.g., cylindrical, spherical). In some embodiments, the core region 566 is separated from the reflector region 564 by a core barrier 565, such as a metal wall. The core region 566 may include one or more fuel sources, such as fissile material, for heating the heat pipe 100. The reflector region 564 may include one or more materials configured to hold / reflect products generated by burning fuel in the core region 566 during the operation of the system 550. For example, the reflector region 564 may include a liquid or solid material configured to reflect neutrons and / or other fission products radially inward toward the core region 566. In some embodiments, the reflector region 564 may completely enclose the core region 566. In other embodiments, the reflector region 564 may only partially enclose the core region 566. In some embodiments, the core region 566 may include control material 567 such as a moderator and / or coolant. The control material 567 may at least partially enclose the heat pipes 100 within the core region 566, allowing heat to be transferred between them.

[0032] In the illustrated embodiment, the system 550 further includes at least one heat exchanger 558 arranged around the heat pipe 100. The heat pipe 100 may extend at least partially into the reflector region 564 from the core region 566 and be thermally coupled to the heat exchanger 558. In some embodiments, the heat exchanger 558 may be located outside or partially inside the reflector region 564. The heat pipe 100 provides a heat transfer path from the core region 566 to the heat exchanger 558. During the operation of the system 550, the fuel in the core region 566 can heat and evaporate the working fluid in the heat pipe 100 in the evaporator region 130 (Figure 1), and the fluid can carry the heat exchanged by the heat exchanger 558 to the condenser region 132 (Figure 1).

[0033] In some embodiments, the heat exchanger 558 may include one or more helical coil tubes enclosing the heat pipes 100. The tubes of the heat exchanger 558 may contain or carry a working fluid (a coolant such as water or another fluid) that carries heat from the heat pipes 100 out of the reactor vessel 552 and the radiation shielding vessel 554 for use in generating electricity, steam, etc. For example, in the illustrated embodiment, the heat exchanger 558 is operably coupled to a turbine 560, a generator 561, a condenser 562, and a pump 563. As the temperature of the working fluid in the heat exchanger 558 rises, the working fluid may begin to boil and evaporate. The vaporized working fluid (e.g., steam) may be used to drive the turbine 560 to convert the thermal potential energy of the working fluid into electrical energy via the generator 561. The condenser 562 may condense the working fluid after it has passed through the turbine 560, and the pump 563 may guide the working fluid back to the heat exchanger 558, where another thermal cycle can be initiated.

[0034] Referring together with Figure 1A-5, in some embodiments of this technology, the heat pipe 100 can be manufactured using an additive manufacturing process to have a very fine second wick 120. Such a heat pipe can improve thermal efficiency, thereby enabling, for example, the heat pipe 100 to effectively transfer heat from the reactor.

[0035] The following examples illustrate some embodiments of this technology. (Example 1) A method for manufacturing a heat pipe using a first material, a second material, and a third material, The steps include forming a first wick structure from the third material described above, The steps of forming a second wick structure on the first wick structure and Includes, The step of forming the wick structure described in the second above is: Mixing the first material and the second material, A mixture of the first material and the second material is heated to a temperature (a) lower than the melting temperature of the first material and (b) higher than the melting temperature of the second material to melt the second material, and The mixture of the first and second materials is cooled to below the melting temperature of the second material so that the second material solidifies and binds together multiple particles of the first material to form a porous structure. Methods that include... (Example 2) The first wick structure and the second wick structure together form a monolithic structure, according to Example 1. (Example 3) Forming the first wick structure is a method of Example 1 or Example 2, comprising forming the first wick structure via a laser metal wire printing process. (Example 4) Mixing the first material and the second material is any one of the methods in Examples 1-3, which includes mixing a powder of the first material containing the particles with a powder of the second material. (Example 5) Mixing the first material and the second material is a method of any one of Examples 1-4, which includes mixing a powder containing the particles, wherein the individual particles are coated with the second material. (Example 6) The first material is a metallic material and the second material is a ceramic material, one of the methods in Examples 1-5. (Example 7) Any one of Examples 1-6, wherein the third material comprises molybdenum, the first material comprises molybdenum, and the second material comprises a ceramic material. (Example 8) The third material is impermeable to fluids, and forming the first wick structure involves forming at least one channel defined by the third material, in any one of the methods of Examples 1-7. (Example 9) A method for forming a porous structure, A step of mixing the first material and the second material, A step of heating a mixture of the first material and the second material to a temperature (a) lower than the melting temperature of the first material and (b) higher than the melting temperature of the second material to melt the second material, The steps include: cooling the mixture of the first material and the second material to below the melting temperature of the second material so that the second material solidifies and binds together multiple particles of the first material to form the porous structure; Methods that include... (Example 10) The method of Example 9, wherein the first material is a metallic material and the second material is a ceramic material. (Example 11) The method of Example 9 or Example 10, wherein mixing the first material and the second material comprises mixing the powder of the first material containing the particles with the powder of the second material. (Example 12) Mixing the first material and the second material is a method of any one of Examples 9-11, which includes mixing a powder containing the particles, wherein the individual particles are coated with the second material. (Example 13) Heating a mixture of the first material and the second material is one of the methods in Examples 9-12, which includes irradiating the mixture of the first material and the second material with a laser. (Example 14) Multiple particles of the first material, A second material that binds the particles of the first material together, the second material having a lower melting temperature than the first material. A porous structure that includes [this]. (Example 15) The first material is a nonmetallic material, porous structure of Example 14. (Example 16) The first material is a ceramic material, a porous structure of Example 14 or Example 15. (Example 17) The first material is at least one of graphite, zirconium carbide, and titanium carbide, a porous structure of any one of Examples 14-16. (Example 18) A porous structure, one of the examples 14-17, wherein the first material is a nonmetallic material and the second material is a metallic material. (Example 19) A porous structure in any one of Examples 14-18, wherein the first material is a ceramic material and the second material is a metallic material. (Example 20) A porous structure, one of the examples 14-19, wherein the first material is a ceramic material and the second material is molybdenum.

[0036] The above detailed description of embodiments of the Art is not intended to be exhaustive or to limit the Art to the exact forms disclosed above. Specific embodiments and examples of the Art are described above for illustrative purposes, but various equivalent modifications are possible within the scope of the Art, as will be apparent to those skilled in the art. For example, the steps are shown in a predetermined order, but other embodiments may perform the steps in a different order. Furthermore, various embodiments described herein may be combined to provide further embodiments.

[0037] As stated above, specific embodiments of the technology are described herein for illustrative purposes, but it will be understood that well-known structures and functions are not described in detail in order to avoid unnecessarily obscuring the description of the embodiments of the technology. Where the context permits, singular or plural terms may also include plural or singular terms.

[0038] As used herein, the terms "and / or" such as "A and / or B" refer to A alone, B alone, and A and B. This disclosure is governed insofar as any material incorporated herein by reference conflicts with this disclosure. Furthermore, the term "equipped with" is used throughout to mean including at least the (multiple) features mentioned, so as not to exclude additional types of the same and / or other features. It will also be understood that while certain embodiments are described herein for illustrative purposes, various modifications can be made without departing from the art. Furthermore, while advantages related to some embodiments of the art are described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments are required to exhibit such advantages in order to fall within the scope of the art. Thus, this disclosure and related art may include other embodiments not expressly shown or described herein.

Claims

1. A method for manufacturing heat pipes, The steps include forming a first wick structure on a part of the inner surface of the heat pipe, The steps of forming a second wick structure and Includes, The step of forming the second wick structure described above is: Mixing the first material and the second material, Heating a mixture of the first material and the second material to a temperature higher than the melting temperature of the first material and lower than the melting temperature of the second material to melt the first material, and The mixture of the first material and the second material is cooled to a temperature lower than the melting temperature of the first material so as to solidify the first material, and the second wick structure is formed by bonding a plurality of particles of the second material together to form a porous structure. Includes, A portion of the second wick structure is formed on the first wick structure, and the other portion of the second wick structure is formed on the remaining portion of the inner surface of the heat pipe. The method wherein the second wick structure has finer porosity than the first wick structure, such that the throughput of the working fluid flow is higher than that of the second wick structure.

2. The method according to claim 1, wherein the first wick structure and the second wick structure integrally form a monolithic structure.

3. The method according to claim 1, wherein forming the first wick structure comprises forming the first wick structure via a laser metal wire printing process.

4. The method according to claim 1, wherein mixing the first material and the second material comprises mixing the powder of the first material and the powder of the second material.

5. The method according to claim 1, wherein mixing the first material and the second material comprises mixing a powder containing the plurality of particles of the second material, wherein each particle is coated with the first material.

6. The method according to claim 1, wherein the first material is a metallic material and the second material is a ceramic material.

7. The method according to claim 1, wherein the first material comprises molybdenum and the second material comprises a ceramic material.

8. The method according to claim 1, wherein forming the first wick structure comprises forming at least one channel defined by a third material.

9. A method for forming a porous structure, A step of mixing the first material and the second material, The steps include depositing a mixture of the first material and the second material onto at least a portion of the first wick structure, A step of heating a mixture of the first material and the second material to a temperature higher than the melting temperature of the first material and lower than the melting temperature of the second material to melt the first material, wherein the first material contains a metal. A step of cooling a mixture of the first material and the second material to below the melting temperature of the first material, wherein the first material forms a coating around the discrete particles of the second material, and the second material is bonded to each other by the coating of the first material, thereby forming a porous second wick structure on at least a portion of the first wick structure. A method comprising the second wick structure having finer porosity than the first wick structure such that the first wick structure has a higher throughput of working fluid flow than the second wick structure.

10. The method according to claim 9, wherein the second material is a ceramic material.

11. The method according to claim 9, wherein mixing the first material and the second material comprises mixing the powder of the first material containing the particles with the powder of the second material.

12. The method according to claim 9, wherein mixing the first material and the second material includes mixing a powder containing the particles.

13. The method according to claim 9, wherein heating a mixture of the first material and the second material includes irradiating the mixture of the first material and the second material with a laser.

14. A heat pipe having a porous structure, wherein the porous structure is arranged on at least a portion of the inner surface of the heat pipe. The aforementioned porous structure is A first wick structure formed on a part of the inner surface of the heat pipe, A porous second wick structure, wherein a portion of the second wick structure is formed on the first wick structure, and the other portion of the second wick structure is formed on the remaining portion of the inner surface of the heat pipe. Includes, The second wick structure comprises a mixture of the first material and the second material, wherein the melting temperature of the first material is lower than that of the second material, and a plurality of particles of the second material are bound together by the solidified first material to form a porous second wick structure. The second wick structure covers the first wick structure at least partially, such that each of the first and second wick structures has an exposed portion. A heat pipe wherein the second wick structure has finer porosity than the first wick structure, such that the throughput of the working fluid flow is higher than that of the first wick structure.

15. The heat pipe according to claim 14, wherein the second material is a nonmetallic material.

16. The heat pipe according to claim 14, wherein the second material is a ceramic material.

17. The heat pipe according to claim 14, wherein the second material is at least one of graphite, zirconium carbide, and titanium carbide.

18. The heat pipe according to claim 14, wherein the second material is a nonmetallic material and the first material is a metallic material.

19. The heat pipe according to claim 14, wherein the second material is a ceramic material and the first material is a metallic material.

20. The heat pipe according to claim 14, wherein the second material is a ceramic material and the first material is molybdenum.

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