Flexible heat pipe

Abstract

The invention relates to a heat pipe (10) extending along a longitudinal path (X), forming an inner space (11) hermetically isolated from the external environment and filled with a predefined volume of two-phase working fluid, the heat pipe (10) comprising a profiled body (20) forming a hollow body closed at at least two opposite longitudinal ends, the profiled body (20) comprising a plurality of longitudinal channels (23) extending along the longitudinal path (X) between the two ends of the profiled body (20), each having a cross section delimited by a bottom formed by a peripheral tubular wall (21) of the profiled body (20), and laterally by two longitudinal walls (22) which extend radially inwards from the peripheral tubular wall (21), the longitudinal channels (23) surrounding a central channel (24), the longitudinal channels (23) being open towards the central channel (24), characterized in that the profiled body (20) comprises one or more flexible portions (30).

Description

Description Title: Flexible Heat Pipe technical field

[0001] This description relates to a flexible heat pipe. This description also relates to a spacecraft comprising such a flexible heat pipe. Previous technique

[0002] During the operation of a spacecraft, such as a satellite, in orbit, a number of onboard electrical and electronic components dissipate a certain amount of heat. This amount is indexed to the intrinsic efficiency of these components and can be significant for some high-power equipment. To maintain the thermal environment of this equipment within temperature ranges compatible with its operation and performance, a heat transfer system is necessary to collect, transport, and then dissipate this heat to a cold source, most often space. Another objective for such a system could be to homogenize the temperature of a piece of equipment over a certain area or to share power between different components in order to maintain a specific temperature level for a set of equipment or structures in a cold environment.

[0003] The heat pipe is one of the various types of heat transfer devices known for this purpose. A heat pipe generally comprises a rigid metal tube forming a central channel in which working fluid moves in the form of vapor, and longitudinal grooves extending axially and around the central channel, inside the tube, designed to advance the working fluid in the form of liquid by capillary action in a direction opposite to that of the vapor.

[0004] Furthermore, it is known that certain dissipative satellite equipment (antennas, panels) can be mobile, moving from a folded configuration that allows the satellite to be housed in the launch vehicle to reach orbit, to a deployed configuration once the satellite is in orbit. Also, in some cases, this equipment can be moved regularly, for example, depending on the satellite's position along its orbit, to provide optimal viewing angles of certain celestial bodies (for observation missions) or towards cold space. However, the mobility of certain equipment, such as antennas and panels, poses integration challenges for traditional solutions due to their rigid structure.

[0005] Furthermore, current systems have limitations in terms of flexibility and length, complicating their use in environments where compactness and mass reduction are crucial. The increasing heat dissipation requirements in satellites necessitate solutions capable of transporting large amounts of heat over long distances, a capability constrained by the rigidity of existing systems.

[0006] For example, we know from document US20140138059 A1 of a flexible axial wick heat pipe that includes an evaporator portion, a condenser portion, and at least one flexible portion. connecting. The flexible portion has a flexible accordion or bellows tube, structurally distinct from the evaporator portion and the condenser portion, and a flexible plate that runs along and inside the heat pipe, including the evaporator portion, the condenser portion.

[0007] The flexible plate divides the interior into a passage for the gaseous or vapor phase, on one side, and a channel for the liquid phase on the other. Vent holes are drilled in the separating plate to allow vapor bubbles contained in the channel to escape into the gaseous phase.

[0008] According to the findings of this Applicant, such an artery heat pipe has the following limitations: - a complex structure: the structure of the heat pipe which has three structurally distinct portions; but also an internal separating plate is particularly complex, which has a significant cost; - difficult sizing: the sizing of the holes in the plate is critical to address the problem of bubbling and drying of the artery, this critical sizing depending on the application; - Difficult integration for heat transfer optimization for certain configurations; the artery heat pipe has the disadvantage that the liquid phase is on one side of the heat pipe, the vapor circulating on a second side of the heat pipe, opposite the first side: depending on the heat pipe integrations, it is not always possible to arrange the hot source ideally with regard to heat transfer, namely to exchange directly with the body on the first side in order to optimize heat transfer at the evaporator, and the cold source on the second side in order to optimize heat transfer to the condenser; - constraints or limitation of folding: folding of the flexible part is possible in a plane perpendicular to the plate, namely that the heat pipe has a preferred folding plane, and unlike folding along the plane of the plate which is more constrained.

[0009] The inventors sought to improve this situation. Summary

[0010] A heat pipe is proposed, configured for use under low or zero gravity, extending along a longitudinal path, forming an interior space hermetically isolated from the external environment and filled with a predefined volume of two-phase working fluid, said heat pipe comprising a profiled body forming a hollow body closed at at least two opposite longitudinal ends, said profiled body comprising a plurality of longitudinal channels extending along the longitudinal path between the two ends of the profiled body, each having a cross-section delimited by a bottom formed by a peripheral tubular wall of the profiled body, and laterally by two longitudinal walls extending radially inwards from the peripheral tubular wall, the longitudinal channels surrounding a central channel, the longitudinal channels being open towards the central channel.The heat pipe is characterized in that the profiled body comprises one or more flexible portions.

[0011] Depending on certain advantageous aspects, the heat pipe may include one or more of the following characteristics, taken individually or according to all possible technical combinations.

[0012] The heat pipe may comprise one or more hermetically sealed flexible sheaths. Each flexible portion may be covered by at least one of said one or more flexible sheaths.

[0013] Each longitudinal channel can delimit a free space suitable for the circulation of the working fluid in liquid form by capillary action.

[0014] The profiled body can be obtained, in whole or in part, by extrusion.

[0015] The heat pipe may comprise one or more rigid sections, each flexible section being arranged between two rigid sections. Each flexible section may be less rigid than the adjacent rigid sections.

[0016] At least one of said one or more flexible portions may exhibit a helical shape along the longitudinal path.

[0017] At least one of said one or more flexible portions may comprise a plurality of individual elements arranged one after the other along the longitudinal path.

[0018] Each individual element can be articulated in relation to directly adjacent individual elements.

[0019] The heat pipe can be mobile between a folded configuration and a deployed configuration, the longitudinal path being different between the folded and deployed configurations.

[0020] According to another aspect, a spacecraft is proposed comprising a body, a deployable appendage movable relative to the body and a heat pipe as described above, in which a first part of the heat pipe is fixed to the body of the spacecraft and a second part of the heat pipe separated from the first part by at least one of said one or more flexible portions is fixed to the deployable appendage. Brief description of the drawings

[0021] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which:

[0022] [Fig. 1] is a schematic view of a heat pipe according to the present description in a folded configuration.

[0023] [Fig. 2] is a schematic view of a heat pipe according to the present description in a deployed configuration.

[0024] [Fig. 3] is a schematic view that represents a cross-section of the heat pipe in Figures 1 and 2.

[0025] [Fig. 4] is a schematic view that represents a longitudinal section of a rigid portion of the heat pipe in Figures 1 and 2.

[0026] [Fig. 5] is a partial schematic view which represents a longitudinal section of the heat pipe of figures 1 and 2 according to a first embodiment.

[0027] [Fig. 6] is a schematic view of the heat pipe of figures 1 and 2 according to a second embodiment.

[0028] [Fig. 7] is a partial schematic view of a first variant of the heat pipe of figures 1 and 2 according to the second embodiment.

[0029] [Fig. 8] is a partial schematic view of a second variant of the heat pipe of figures 1 and 2 according to the second embodiment.

[0030] [Fig. 9] is a partial schematic view of a third variant of the heat pipe of figures 1 and 2 according to the second embodiment. Description of the implementation methods

[0031] A heat pipe 10 according to the present invention is now described, firstly with reference to figures 1 to 4.

[0032] The heat pipe 10 extends along a longitudinal path X. In the following description, orientation qualifiers such as "longitudinal" and "radial" are defined, unless otherwise specified, by reference to the longitudinal path X. A radial direction is a direction perpendicular at a given point on the longitudinal path X. Furthermore, unless otherwise specified, the adjectives "inside," "internal," "outside," and "external" are used with reference to a radial direction such that the inside / internal (i.e., radially inside / internal) part of an element is closer to the longitudinal path X than the outside / external (i.e., radially outside / external) part of the same element.

[0033] The heat pipe 10 can be an elongated device along the longitudinal path X. The longitudinal path X can have a length between 0.3 m and 20 m. In other words, the heat pipe 10 can have a length between 0.3 m and 20 m.

[0034] The heat pipe forms an internal space 11 that is hermetically sealed from the external environment and filled with a predetermined volume of two-phase working fluid. The working fluid can be ammonia, propylene, methanol, water, or any other medium exhibiting liquid-vapor equilibrium under saturated conditions. The pressure of the working fluid in the internal space 11 of the heat pipe 10 can range from 0.01 bar to 100 bar, or even higher.

[0035] The heat pipe 10 comprises a profiled body 20 forming a hollow body closed at at least two opposite longitudinal ends. The heat pipe 10 is capable of extracting heat from a hot source 13 and transferring it to a cold source 14 by means of a two-phase working fluid circulating within the profiled body 20. The hot source 13 may be a heat-dissipating electronic device. The cold source 14, as will be described later, may be space, other heat-transporting equipment, or a heat sink. The profiled body 20 may comprise a first end 20a and a second end 20b, opposite each other along the Longitudinal path X. The profiled body 20 can be closed at the first end 20a and at the second end 20b, for example by respective closing elements.

[0036] Most notably visible in Figures 3 and 4, the profiled body 20 comprises a plurality of longitudinal channels 23 extending along the longitudinal path X between the two ends of the profiled body 20. Each longitudinal channel 23 may be parallel to the longitudinal path. Each longitudinal channel 23 has a cross-section delimited by a bottom formed by a peripheral tubular wall 21 of the profiled body 20, and laterally by two longitudinal walls 22 extending radially inward from the peripheral tubular wall 21. The longitudinal channels 23 surround a central channel 24. The longitudinal channels 23 are open in the direction of the central channel 24.

[0037] Each longitudinal channel 23 can typically be parallel to the longitudinal path, at least in the rigid sections. The longitudinal channels 23 can be distributed angularly, and preferably regularly around the central channel. The longitudinal channels are separated from each other, at least in the rigid portions. In this sense, there is no fluid communication, i.e., communication in the liquid phase, between two adjacent channels separated by a wall along the lengthwise section of the profile where the two adjacent channels are separated by the wall.

[0038] This disclosure may, however, implement the technical solution of document EP4092371, with the presence, locally, at a position along the longitudinal path, of at least one circumferential transfer channel, on one or more rigid parts of the profile and / or on the flexible part(s). This transfer channel may be arranged transversely to the local axial direction and provides fluid communication between all or part of the plurality of longitudinal channels, the longitudinal walls being then interrupted, partially or totally, at the location of the circumferential channel. This circumferential channel may be delimited radially inwards by a cover ring, the cover ring being interposed between the circumferential transfer channel and the longitudinal channel.

[0039] The central channel 24 forms a free space for the transport of the fluid in its vapor form. In this sense, the central channel 24 can preferably be free of solid obstructions in its path.

[0040] Each longitudinal channel 23 can be filled with working fluid in liquid form. The central channel 24 can be partially filled with working fluid in liquid form, particularly at the condensation portion 42.

[0041] The heat pipe 10 can be adapted for the movement of the working fluid in vapor form in the central channel 24 and in liquid form in the longitudinal channels 23. The longitudinal channels 23 can form peripheral longitudinal grooves extending along the longitudinal path X between the two opposite ends of the profiled body 20 around the central channel 24, i.e., from the first end 20a to the second end 20b of the profiled body 20. As will be seen later, it is possible that one or more longitudinal channels 23 may include one or more segments separated by discontinuities in the tube wall 21 and The walls 22. The longitudinal channels 23 can be adapted to advance the working fluid in liquid form in a direction opposite to that of the vapor in the central channel 24. The longitudinal channels 23 can be adapted to advance the working fluid in liquid form by capillary action. In this sense, the longitudinal channels 23 can form a capillary network. The longitudinal channels 23 can be distributed angularly, preferably regularly, around the central channel 24. The tube wall 21 can have an external diameter of between 3 mm and 50 mm, preferably between 5 mm and 30 mm.

[0042] At least one or more of said longitudinal channels 23 may have a cross-section normal to the longitudinal path X, having a general concavity. More specifically, at least one or more of said longitudinal channels 23 may have a cross-section in the form of a circular arc or an oval arc, a trapezoidal shape, or even a teardrop shape open towards the channel. Each longitudinal channel 23 may define a free space adapted to receive the working fluid in liquid form. The free space may be adapted to the circulation of the working fluid in liquid form by capillary action. Each longitudinal channel 23 may have dimensions and / or a shape adapted to the circulation of the working fluid in liquid form by capillary action. By "free space" is understood to mean an area devoid of any solid part or material structure and, in particular, suitable for receiving the working fluid.In particular, each longitudinal channel 23 can be free of porous material. Generally, the heat pipe 10 can be free of porous material for the circulation of the two-phase working fluid, especially sintered (i.e., obtained by a sintering process), in the form of fabric layers or metal film mats. The heat pipe 10 can be free of porous material having a pore size less than or equal to 50 µm. The absence of such porous materials in the longitudinal channels reduces pressure losses and improves fluid flow, increasing heat transfer efficiency.

[0043] Remarkably, the streamlined body 20 includes one or more flexible sections 30. The integration of these flexible sections allows for adaptation to various heat pipe configurations, facilitating installation in constrained environments and optimizing available space. Such a heat pipe 10 is thus suitable for operation in space environments, being flexible, thermally efficient, and relatively inexpensive to manufacture. The structure of said one or more flexible sections will be described in more detail later.

[0044] By "flexible," it is understood that each flexible portion 30 of the profiled body 20 is adapted to be deformed, bent, curved, or flexed, preferably reversibly, for example, under the effect of external forces, in order to modify the longitudinal path X of the heat pipe 10 at the flexible portion 30. Alternatively, each flexible portion 30 may have sufficient flexibility to modify the longitudinal path X of the heat pipe 10 locally at the flexible portion 30. The term "flexible" refers to the ability of an object to bend, curve, or deform without breaking, thus allowing adjustments to its shape or position. In contrast, a "rigid" object is inflexible and retains its original shape, resisting deformation.

[0045] Preferably, the flexible portion of the heat pipe's profiled body can be designed to allow angular deformation in any plane containing the longitudinal axis of the rigid portion of the profiled body, thus providing multidirectional flexibility without any preferred direction constraint. The bending (specifically, the longitudinal path of the flexible portion of the profiled body) may even extend beyond a single plane into all three dimensions of space.

[0046] In this sense, each flexible portion 30 can be less rigid than adjacent portions of the profiled body 20. In contrast, the portions adjacent to each flexible portion 30 can be referred to hereafter as "rigid portions 40". Each flexible portion 30 can therefore be less rigid than the adjacent rigid portions 40 of the profiled body 20. More generally, each of said one or more flexible portions 30 can be less rigid than each of said one or more rigid portions 40. The longitudinal path X can be fixed, i.e., unchangeable, at each rigid portion 40. Each rigid portion 40 can be straight or curved. In this sense, the longitudinal path X of the heat pipe 10 can be straight or curved at each rigid portion 40. The profiled body 20 can include one or more rigid portions 40. Each flexible portion 30 can be arranged between two rigid portions 40.The profiled body 20 may comprise an alternating succession of rigid portions 40 and flexible portions 30. Each flexible portion 30 may be structurally independent of the adjacent rigid portions 40. The heat pipe may include connecting elements between each rigid portion 40 and each flexible portion 30. A variant is also possible in which each flexible portion 30 is formed from the same material as the adjacent rigid portions 40. Figure 4 is a longitudinal cross-sectional view of a rigid portion 40 of the heat pipe 10.

[0047] A force exceeding a threshold force may be required to modify the longitudinal path X at at least one of the one or more flexible sections 30, and preferably at each of the one or more flexible sections 30. In this way, the heat pipe 10 is held in position when no force or a small force is applied to it. The internal pressure exerted by the two-phase working fluid can generate the threshold force necessary to adjust the longitudinal path X at at least one of the one or more flexible sections.

[0048] The profiled body 20 therefore includes longitudinal channels 23 at the level of each flexible portion 30. Similarly, the profiled body 20 can include longitudinal channels 23 at the level of each rigid portion 40. In other words, each longitudinal channel 23 extends longitudinally at the level of said one or more flexible portions 30, and where applicable at the level of said one or more rigid portions.

[0049] Each flexible section 30 can be capable of forming at least one bending angle θ between 0° and 180° inclusive, or even between 0° and 360° inclusive. The longitudinal path thus forms an angle equivalent to the bending angle θ at the flexible section 30. When said flexible section 30 forms a bending angle θ of 180°, it can be rectilinear, that is, the longitudinal path θ is rectilinear at the level of the flexible section 30. When said flexible section 30 When the flexible portion forms a bending angle of 0° or 360°, it can have a U-shape. Finally, when the flexible portion 30 forms a bending angle between 0° and 180° or between 0° and 360°, for example 90° as shown in Figure 2, it can have a bent angle. Each flexible portion can be capable of forming several bending angles. In this sense, the flexible portion can have an S-shape, for example.

[0050] The profiled body 20 may include one or more openings 25 in at least one flexible portion 30. Each of these one or more openings 25 may form a discontinuity in one or more longitudinal channels 23. Remarkably, the inventors have found that such openings 25 do not impede the flow of the working fluid in liquid form. Furthermore, each of these one or more openings may form a circumferential channel that connects all or part of the longitudinal channels 23 with fluid. In this way, these one or more openings 25 can ensure a uniform distribution of the pressure of the working fluid in liquid form within the longitudinal channels. In other words, each of these one or more openings 25 has a pooling and sharing function for the fluid supply, providing the longitudinal channel 23 with the greatest demand for fluid from the others.The flexible portion 30 may have one or more openings 25 when the bending angle 0 is different from 180°, and preferably at the part having the largest radius of curvature to form the bending angle 0. The external sealing of the heat pipe having such openings can be achieved by a sheath 50 which covers the flexible portion 30. Such a sheath is described in more detail later.

[0051] The heat pipe can be movable between a folded configuration (CR) and an extended configuration (CD). The longitudinal path X can differ between the folded configuration (CR) and the extended configuration (CD). The longitudinal path X can be straight or curved in the folded configuration (CR). Similarly, the longitudinal path X can be straight or curved in the extended configuration (CD). Regardless of the configuration of the heat pipe 10, the longitudinal path X can be straight or form one or more bends. Furthermore, the longitudinal path X can be planar or three-dimensional, regardless of the configuration of the heat pipe 10.

[0052] The heat pipe 10 may have a reduced footprint in the folded configuration CR compared to the deployed configuration CD. In this sense, the heat pipe 10 may be more compact when folded than when deployed. At least one bend angle 0 of one or more of said flexible portions 30 may be smaller in the folded configuration CR than in the deployed configuration CD.

[0053] The hot source 13 may be in contact with an evaporation portion 41 of the profiled body 20. The evaporation portion 41 may coincide with a first rigid portion 40 from among said one or more rigid portions 40. Also, the evaporation portion 41 may be arranged at the first end 20a of the heat pipe 10 along the longitudinal path X. The cold source 14 may be in contact with a condensation portion 42 of the profiled body 20. The condensation portion 42 may coincide with a second rigid portion 40 from among said one or several rigid portions 40. The condensation portion 42 can be arranged at the second end 20b of the heat pipe 10 along the longitudinal path X.

[0054] In the example shown in Figures 1 and 2, the profiled body 20 comprises a single flexible portion 30 arranged between a rigid portion 40 corresponding to the evaporation portion 41 and another rigid portion 40 corresponding to the condensation portion 42. The heat pipe 10 therefore has a bent shape, such as an L or a V. However, it is possible for the profiled body 20 to comprise several (two or more) flexible portions 30. Thus, the heat pipe 10 could, for example, have a Z-shaped conformation.

[0055] The heat pipe 10 is configured for use in low or zero gravity, for example, in space. For instance, the heat pipe 10 can be configured for use in a spacecraft or device sent into space. In particular, this could be a satellite for telecommunications, surveillance, or other functions. The heat pipe 10 can be used in total weightlessness or in low or moderate gravity, for example, on the surface of a celestial body such as the Moon or Mars. The heat pipe 10 can be used with zero or very low external pressure, or even at atmospheric pressure. In general, the heat pipe can be used regardless of the external pressure.

[0056] The heat pipe 10, due to its flexibility, is suitable for use in a spacecraft (for example a satellite) comprising a deployable appendage, where a first part of the heat pipe 10 (for example a first rigid portion 40) is fixed to the body of the spacecraft and a second part of the heat pipe 10 (for example a second rigid portion 40) separated from the first part by at least one of said one or more flexible portions 30, is fixed to the deployable appendage.

[0057] One advantage of the heat pipe's flexibility is that it facilitates its integration into a spacecraft. It allows it to be connected to two parts requiring thermal connection (panels or equipment), while also offering the possibility of moving these parts relative to each other.

[0058] The flexibility of the heat pipe 10 also reduces constraints related to manufacturing tolerances when connecting it to other components. Thanks to its flexibility, the heat pipe adapts to variations in the relative positions of the parts to be thermally connected. The heat pipe can be connected to various components without requiring extreme precision in the alignment or adjustment of these components. In other words, this flexibility makes it possible to compensate for dimensional deviations and imperfections, thus facilitating integration into complex systems. The flexibility of the heat pipe also allows a standard-sized heat pipe to be connected to components whose relative position may vary from one system to another. This characteristic is particularly advantageous in technological fields where the configuration of each system is unique, such as in the space sector where each satellite is generally manufactured individually.

[0059] As a result, the assembly process becomes more efficient and less costly, while maintaining optimal thermal system performance. Such an assembly process can be called "MAIT" for spacecraft, standing for "Manufacturing, Assembly, Integration, and..." Testing” - this is a process where the components of a satellite are manufactured, assembled, integrated into a functional system, and then rigorously tested to validate their performance and reliability before launch.

[0060] The heat pipe 10 may include one or more flexible, airtight sheaths 50. Each flexible section 30 may be hermetically sealed by at least one of said flexible sheaths 50. The heat pipe can therefore be sealed at each flexible section by said flexible sheaths 50. The sheath 50 may be configured to prevent any leakage of working fluid to the outside.

[0061] It is possible for a space or gap to exist between the sheath and the profiled body of the heat pipe. This space can allow a certain degree of freedom of movement of the profiled body within the sheath, without compromising the seal. Furthermore, this space can receive working fluid passing through the openings 25, allowing for uniform fluid distribution and thus improving heat transfer efficiency. Alternatively, each sheath 50 can closely cover the profiled body 20, or even be clamped onto it. In other words, each flexible section 30 can extend inside one or more of the aforementioned flexible sheaths 50. This ensures the sealing and hermetic insulation of the internal space 11 to the outside of the heat pipe 10 at each flexible section 30.

[0062] Preferably, the heat pipe 10 may include a flexible sheath 50 associated with each flexible portion 30. In this configuration, each flexible portion 30 may be covered by one or more flexible sheaths 50. Each sheath 50 may be attached on either side to the adjacent rigid portions 40 of the associated flexible portion 30. This attachment may be achieved by welding, using a fixing sleeve. The heat pipe 10 may therefore include several structurally distinct flexible sheaths 50, preferably equal in number to the number of flexible portions 30. Alternatively, one or more flexible sheaths 50 may cover several of the one or more flexible portions 30. In this case, the single flexible sheath 50 may cover the rigid portions 40 located between the flexible portions covered by this sheath.

[0063] Each flexible 50 hose can be particularly airtight for the two-phase working fluid, in both liquid and vapor forms. Each flexible 50 hose can be made of polymer, for example PTFE, or of corrugated metal, for example stainless steel, titanium, or aluminum.

[0064] The profiled body 20 can be obtained, in whole or in part, by extrusion. Extrusion can be the primary manufacturing operation. Using a press, an aluminum alloy is forced through a die with the desired shape to obtain the profiled body 20 at the die's exit. Generally, the profiled body 20 can be metallic, particularly aluminum. In particular, each of the aforementioned one or more rigid portions 40 can be obtained by extrusion. Extrusion manufacturing of the profiled body ensures precise and economical production, enhancing structural robustness. Alternatively, the profiled body 20 can be obtained, in whole or in part, by a process additive manufacturing, or by conventional manufacturing and assembly techniques such as machining or electro-erosion for manufacturing and welding or brazing for assembly.

[0065] A first embodiment of the heat pipe 10 is now described with reference to Figure 5.

[0066] In the first embodiment, at least one or more of said flexible portions 30 may have a helical or spiral shape along the longitudinal path X. In this sense, said flexible portion 30 may comprise a plurality of successive turns along the longitudinal path X. The helical shape confers flexibility to the flexible portion 30. Preferably, each flexible portion 30 may have such a helical shape. To achieve this, the profiled body 20 may include a through helical slot 33. Such a slot 33 may be obtained by machining in the profiled body 20, for example, obtained by extrusion.

[0067] The slot 33 can form one or more openings 25. Each turn of the slot 33 can form all or part of one of the openings 25. In this sense, each turn of the slot 33 can form a circumferential channel that connects all or part of the longitudinal channels 23 to the fluid. In a particular case, the slot 33 can form a single helical opening 25. The slot 33 can be adapted to advance the working fluid in liquid form in a direction opposite to that of the vapor in the central channel 24. Advantageously, the helical shape of the flexible portions offers increased flexibility, allowing for easier adjustments in confined spaces, and also contributes to improved fluid circulation, leading to increased heat transfer efficiency, thereby enhancing the overall performance of the heat pipe.

[0068] The flexible helical portion 30 can have a length 11 ranging from 0.1 to 10 m. The helical slot 33 can have a pitch I2 ranging from 0.1 mm to 100 mm. The helical slot 33 can have a width I3 ranging from 0.1 mm to 5 mm. The helical slot 33 can form an angle α between 90° (exclusive) and 0° (exclusive) with respect to the longitudinal path, preferably between 45° (inclusive) and 0° (exclusive). The parameters listed above can be considered in a rectilinear configuration of the flexible portion 30 (Le. for a longitudinal path X forming a straight segment at the level of the flexible portion 30). The dimensions of the helical slot 33, with a pitch I2 varying between 0.1 mm and 100 mm, a width I3 ranging from 0.1 mm to 5 mm, and an angle between 0° and 90° excluded, offer optimal flexibility to the flexible portion 30.These values ​​allow for flexibility in the flexible portion, meeting the specific needs of integration in complex environments where space is limited.

[0069] Each of said one or more flexible portions 30 may be a single piece. Each of said one or more flexible portions 30 may be obtained by machining an extruded profile. In a particular case, the profiled body 20 may be a single piece. In this sense, the profiled body 20 may be entirely obtained by extrusion, each of said one or more flexible portions 30 being formed, for example by machining, from the profiled body 20 obtained by extrusion.

[0070] In what follows, a second embodiment of the heat pipe 10 is described with reference to figures 6 to 9.

[0071] In the second embodiment, at least one or more of said flexible sections 30 may comprise a plurality of individual elements 31 arranged one after the other along the longitudinal path X. Such segmentation confers flexibility to the flexible section 30. It is understood that each individual element 31 therefore has a tubular shape. Each individual element 31 comprises a segment of each longitudinal channel 23. The heat pipe may have at least one configuration in which each individual element is in fluidic communication (i.e., in hydraulic connection) with the directly adjacent individual elements via at least one longitudinal channel 23.

[0072] According to a first variant shown in Figures 6, 8, and 9, each individual element 31 can be articulated relative to directly adjacent individual elements 31. The use of articulated individual elements allows for additional mobility and adaptability, facilitating the adjustment of the heat pipe. Each individual element can have a mechanical connection to directly adjacent individual elements.

[0073] Two adjacent individual elements 31 can be articulated relative to each other by complementary form. In other words, two adjacent individual elements 31 can include complementary reliefs 32a; 32b adapted to articulate the adjacent individual elements 31 relative to each other. For this purpose, each individual element 31 can include such reliefs longitudinally on each side. Said complementary reliefs 32a; 32b can include a male relief 32a and a female relief 32b cooperating with each other, for example by interlocking. Thus, two adjacent individual elements 31 can respectively include a male relief 32a and a female relief 32b cooperating with each other so as to form a pivoting joint between the two adjacent individual elements 31. Each individual element 31 can include a male relief 32a and a female relief 32b, preferably longitudinally opposed.The set of individual elements 31 may be identical. Alternatively, the plurality of individual elements 31 may comprise an alternating succession of individual elements 31 of a first type and individual elements 31 of a second type, where each individual element 31 of the first type comprises two male reliefs 32a and where each individual element 31 of the second type comprises two female reliefs 32b.

[0074] Each individual element 31 can be pivotally articulated about at least one radial axis (i.e., perpendicular to the longitudinal path X) relative to directly adjacent individual elements 31. Each individual element 31 can be pivotally articulated by means of a ball joint or spherical joint relative to directly adjacent individual elements 31.

[0075] The plurality of individual elements 31 may include two individual end elements 31 which are opposed along the longitudinal path X and which cooperate in a fixed or articulated manner with a portion (for example a rigid portion 40) of the profiled body 20, adjacent to the flexible portion 30.

[0076] The complementary reliefs 32a; 32b between two adjacent individual elements 31 can be adapted to limit, or even block, a translational displacement of one of the individual elements 31 relative to the other along the longitudinal path X. Alternatively, or in addition, the complementary reliefs 32a; 32b between two adjacent individual elements 31 can be adapted to limit, or even block, a rotation of one of the individual elements 31 relative to the other around an axis coinciding with the longitudinal path X locally at the level of the individual element in question, in particular to keep the longitudinal channels aligned between the two individual elements. For example, for this purpose, one of the two adjacent individual elements 31 may include a lug extending radially outwards and which is received in a hole formed in the other of the two individual elements 31.

[0077] In a second variant shown in Figures 6 and 7, the individual elements 31 can be structurally independent of each other. The plurality of individual elements 31 can be contained within the flexible sheath 50 covering the flexible portion 30 so as to maintain the continuity of the individual elements 31 one after the other along the longitudinal path X.

[0078] The individual elements 31 can be monolithic. Furthermore, all or part of the individual elements 31 can be obtained by additive manufacturing.

[0079] Compared to the prior art disclosed US20140138059 A, the heat pipe can typically exhibit all or some of the following advantages: - a simplified design; the rigid portions and the flexible portion(s) of the profiled body having the same arrangement of longitudinal channels, - Easy sizing; with the longitudinal channels open towards and into the central channel, any vapor bubbles contained in the liquid phase inside the channels can easily escape to the central channel, without difficulty or special sizing. - Easier integration; the cold source at the evaporator and the hot source at the condenser can be arranged indifferently in different positions around the profiled body, without loss of performance in terms of heat transfer, in particular thanks to the plurality of longitudinal channels distributed angularly around the central channel which distribute the liquid phase around the perimeter of the profiled body, - Multidirectional flexibility without a preferred direction constraint: in particular, the flexible portion(s) of the profiled body can be designed to allow angular deformation in any plane containing the longitudinal axis of the rigid portion of the profiled body; furthermore, the central channel is free of any solid body imposing a preferred bending direction. The bending (specifically, materialized by the longitudinal path of the flexible part of the profiled body) may not even be confined to a single plane but, on the contrary, extend in all three dimensions of space.

Claims

Demands

1. A heat pipe (10) configured for use under low or zero gravity, extending along a longitudinal path (X), forming an internal space (11) hermetically sealed from the external environment and filled with a predefined volume of two-phase working fluid, said heat pipe (10) comprising a profiled body (20) forming a hollow body closed at at least two opposite longitudinal ends, said profiled body (20) comprising a plurality of longitudinal channels (23) extending along the longitudinal path (X) between the two ends of the profiled body (20), each having a cross-section delimited by a bottom formed by a peripheral tubular wall (21) of the profiled body (20), and laterally by two longitudinal walls (22) extending radially inward from the peripheral tubular wall (21), the longitudinal channels (23) surrounding a central channel (24), the longitudinal channels (23) being open in the direction of the central canal (24),characterized in that the profiled body (20) comprises one or more flexible portions (30).

2. Heat pipe (10) according to the preceding claim, wherein comprising one or more hermetically sealed flexible sheaths (50), and in which each flexible portion (30) is covered by at least one of said one or more flexible sheaths (50).

3. Heat pipe (10) according to any one of the preceding claims, wherein each longitudinal channel (23) delimits a free space adapted to the circulation of the working fluid in liquid form by capillary action.

4. Heat pipe (10) according to any one of the preceding claims, wherein the profiled body (20) is obtained, in whole or in part, by extrusion.

5. Heat pipe (10) according to any one of the preceding claims, wherein it comprises one or more rigid portions (40), each flexible portion (30) being arranged between two rigid portions (40), and wherein each flexible portion (30) is less rigid than the adjacent rigid portions (40).

6. Heat pipe (10) according to any one of the preceding claims, wherein at least one of said one or more flexible portions (30) has a helical shape along the longitudinal path (X).

7. Heat pipe (10) according to any one of claims 1 to 4, wherein at least one of said one or more flexible portions (30) comprises a plurality of individual elements (31) arranged one after the other along the longitudinal path (X). [Claims] Heat pipe (10) according to the preceding claim, wherein each individual element (31) is articulated with respect to the directly adjacent individual elements (31).

9. Heat pipe (10) according to any one of the preceding claims, which is movable between a folded configuration (CR) and a deployed configuration (CD), the longitudinal path (X) being different between the folded configuration (CR) and the deployed configuration (CD).

10. A spacecraft comprising a body, a deployable appendage movable relative to the body and a heat pipe (10) according to any one of the preceding claims, wherein a first part of the heat pipe (10) is fixed to the body of the spacecraft and a second part of the heat pipe (10) separated from the first part by at least one of said one or more flexible portions (30) is fixed to the deployable appendage.

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