Penetration-free heat transfer system

Abstract

A heat transfer system. The heat transfer system has a barrier having a first side and a second side, the first side disposed on a hot side of the heat transfer system and the second side being disposed on the cold side of the heat transfer system. A first plurality of protrusions extends from the first side of the barrier, and a second plurality of protrusions extend from the second side of the barrier. A first heat pipe having a first plurality of flanges is joined on the first side of the barrier by fasteners engaging the first plurality of protrusions. A second heat pipe having a second plurality of flanges is joined to the second plurality of flanges being joined on the second side of the barrier by fasteners engaging the second plurality of protrusions.

Description

GOVERNMENT INTEREST

[0001] The invention described herein may be manufactured and used by or for the Government of the United States for all government purposes without the payment of any royalty.FIELD OF THE INVENTION

[0002] The embodiments herein generally relate to heat transfer in space vehicles.BACKGROUND

[0003] Existing spaceflight thermal control systems utilize pumped fluid loops. Pumped fluid loops for spaceflight thermal control systems utilize pipes to transport fluid to move heat from the crew cabin to exterior radiators. The pipes must traverse the wall of the spacecraft, including in the case of crewed spacecraft, the crew cabin, i.e., the pressure vessel, twice to close the loop. Typical pumped fluid loop designs include a redundant pumped fluid loop for a total of four pressure vessel penetrations. Human spaceflight thermal control subsystems for space capsules (Gemini, Apollo, Soyuz, Dragon, Starliner, Russian space station modules) tend to be 1-loop pumped fluid loop systems and human spaceflight thermal control systems for larger systems (Shuttle, ISS) tend to be 2-loop pumped fluid loop systems. For either 1-loop or 2-loop systems, the pumped fluid loop penetrates the pressure vessel and, therefore, becomes part of the crew cabin's hermeticity. The penetrations for the pumped fluid loop must contain the crew cabin's pressure and a failure is tantamount to a crew cabin pressure vessel leak.

[0004] Additionally, pumped fluid loop systems require a fluid that has sufficient thermal performance, good thermal performance characteristics, does not pose risks to the hermeticity of the PFL when cooled to its minimum operating temperature and is safe for being near humans. These three constraints are difficult to satisfy. Such designs from early in the space ages usually had to cut corners and accept unsafe fluids (e.g., in the Gemini spacecraft) or accept fluids with marginal safety and low temperature operation (e.g., the Apollo and Soyuz spacecrafts). Pumped fluid loop designs today have access to a wider array of fluid choices, but the problem is still over constrained such that fluids are often safe but have marginal performance.

[0005] A continuing, unaddressed need exists for systems and methods to achieve a human spaceflight thermal control system that operates without any penetrations in the crew cabin.

[0006] A continuing, unaddressed need exists a thermal control system in a spacecraft in which human safe fluids are inside and high performance, but potentially dangerous, fluids are kept outside the spacecraft.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The embodiments herein will be better understood from the following detailed description of the drawings, in which:

[0008] FIG. 1 is a representative heat pipe;

[0009] FIG. 2 is a cross section of a representative heat pipe;

[0010] FIG. 3 is a cross section of a representative heat pipe;

[0011] FIG. 4 is a diagram depicting a heat transfer system of the current disclosure;

[0012] FIG. 5 is a diagram depicting a heat transfer system of the current disclosure

[0013] FIG. 6 is a front view of an example barrier;

[0014] FIG. 7 is a side view of an example barrier;

[0015] FIG. 8 is a front view of an example heat transfer system;

[0016] FIG. 9 is a side view of an example heat transfer system;

[0017] FIG. 10 is a top view of an example heat transfer system;

[0018] FIG. 11 is a front view of an example barrier;

[0019] FIG. 12 is a side view of an example barrier;

[0020] FIG. 13 is a front view of an example barrier;

[0021] FIG. 14 is a side view of an example barrier;

[0022] FIG. 15 is an exploded view of an example heat transfer system;

[0023] FIG. 16 is an example method of use of a heat transfer system on a space vehicle; and

[0024] FIG. 17 is an example method of use of a heat transfer system on a space vehicle.DETAILED DESCRIPTION

[0025] Embodiments of the disclosed development, its various features, and the advantageous details thereof, are explained more fully concerning the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure what is being disclosed. Examples may be provided, and when so provided are intended merely to facilitate an understanding of how the invention may be practiced and to further enable those of skill in the art to practice its various embodiments. Accordingly, examples should not be construed as limiting the scope of what is disclosed and otherwise claimed.

[0026] Referring to FIG. 1 there is shown a representative heat pipe 10. The heat pipe 10 has an evaporator portion 12 and a condenser portion 14 separated by an adiabatic section 16. Heat 18 to be moved is transferred into the heat pipe 10 in the evaporator portion 12 to cause a phase change in an internally disposed heat pipe fluid (not shown in FIG. 1), e.g., vaporization to a vapor phase, within the heat pipe 10. Heat 20 to be released exits at the condenser portion 14 where the fluid undergoes the reverse phase change, e.g., condensation back into a liquid. The liquid is then transported back, such as wicking by capillary transport, to the evaporator portion of the heat pipe 10 to absorb additional heat.

[0027] Representative heat pipe configurations are shown in cross section in FIGS. 2 and 3. As depicted in FIG. 2, which is a view of Section 2-2 at the evaporator portion 12 of the heat pipe 10 of FIG. 1, a heat pipe can have internally extending axial ridges 22 defining axial grooves 24. To achieve wicking from the condenser portion 12 to the evaporator portion 14, the heat pipe 10 relies on capillary fluid flow. As depicted in FIG. 2, which is a view of Section 2-2 at the evaporator portion 12 of the flexible heat pipe 10 of FIG. 1 but can be identical to that of the condenser portion 14, the flexible heat pipe 10 can have internally extending axial ridges 22 defining axial grooves 24. The axial ridges and grooves can be oriented in a longitudinal direction generally parallel to a central axis of the heat pipe and can be manufactured according to known means, including by machining the interior of the evaporator and condenser portions. The grooves can be sized and shaped according to known means to serve as capillary channels suitable to move the fluid 26 via capillary action from the condenser portion 14 to the evaporator portion 12.

[0028] The fluid 26 is disposed in the interior portion 28 of the heat pipe 10 and is in fluid communication with the evaporator portion 12 and the condenser portion 14. Upon heat 18 being transferred into the heat pipe 10 at the evaporator portion 12, the fluid 26, which can be water, for example, vaporizes in the interior portion 28 of the heat pipe 10. At the condenser portion 14, the fluid condenses back to a fluid as it releases the transported heat out of the heat pipe and is wicked, e.g., by capillary action, in the axial grooves 24 defined by the axial ridges 22. As depicted in the heat pipe in FIG. 2, a cylindrical-shaped heat pipe can transfer heat 18 substantially uniformly over the entire exterior surface of the heat pipe 10.

[0029] The heat pipe 10 shown in FIG. 3 operates in substantially the same manner as that shown in FIG. 2, with the difference being the heat pipe 10 includes a flange 28. The flange 28 can be integral with, unitary, or otherwise be joined in heat-conductive relationship to, the heat pipe 10 to provide addition heat transfer surface area. The heat pipe 10 can have more than one flange 28, and the flange 28 can extend the length of the heat pipe 10, or a portion of the length. In the configuration of a heat pipe 10 having a flange 28, the flange 28 can be in heat-conductive contact with a heat source, such that heat 18 transfer is non-uniform, with relatively more heat 18 being transferred via the flange 28 into (or out of) the heat pipe 10.

[0030] Referring now to FIG. 4 there is disclosed a heat transfer system 100 involving two heat pipes. While two heat pipes are illustrated, it is understood that the heat transfer can be between two pumped fluid loops, two solid thermal conductors, and other combinations of heat transfer components. A first heat pipe 110 is joined in a thermally conductive relationship with a second heat pipe 120 across a solid barrier. By “solid barrier” is meant a penetration-free barrier in which there are no holes, gaps, or other penetrations through which any gas, fluid, vapor, or solid can traverse through the barrier. For descriptive purposes, the solid barrier of the present disclosure will be referred to simply as a “barrier” and is understood in the embodiments herein as a portion of a spacecraft outer wall that separates a crewed cabin from outer space. In the heat transfer system 100 illustrated in FIG. 4, a barrier 132 separates a relatively hot side 126 of the heat transfer system 100 from a relatively cold side 128. For descriptive purposes in the illustrated embodiment, the first heat pipe 110 can be considered on the relatively hot side 126 of the heat transfer system 100, and the second heat pipe can be considered on the relatively cold side 128 of the heat transfer system 100. While heat can potentially flow in either direction depending on thermal conditions, in the configuration described, heat flows in the direction indicated by arrow 130. The two heat pipes are each configured to be joined in a heat-conductive relationship at the barrier 132 for conductive heat transfer through the barrier 132. Joining to the barrier 132 can be by any suitable means that does not penetrate the barrier 132 and which effects suitable normal forces to facilitate sufficient conductive heat transfer across the barrier 132. Examples of joining include glueing, bonding, adhering, bolting, screwing, and combinations thereof.

[0031] The first heat pipe 110 has an evaporator portion 112 in fluid communication with a condenser portion 114, as described above with respect to FIGS. 1 and 2. In addition, the first heat pipe 110 has a flange 134 joined in heat-conductive relationship with both the first heat pipe 110 and the barrier 132. The barrier 132 can be a panel, wall, or other structure tending to prevent heat transfer from the relatively hot side 126 to the relatively cold side 128 of the heat transfer system 100. In like manner, the second heat pipe 120 has an evaporator portion 122 in fluid communication with condenser portion 124, as described above with respect to FIGS. 1 and 2. The second heat pipe 120 has a flange 136 joined in heat-conductive relationship with both the second heat pipe 120 and the barrier 132.

[0032] In an embodiment the heat pipes and flanges can be made of metal, e.g., aluminum, titanium, and / or stainless steel, and the flange of each heat pipe can be unitary with the heat pipe, or separately joined, such as by welding. The heat pipes can be generally cylindrically shaped and can be any length, diameter, and shape suitable for the desired heat transfer rate. The heat pipes can be generally straight along their entire length, or curved along a portion of their length, as shown in FIG. 4. The configuration of size and shape of the heat pipes can be determined to achieve the desired heat transfer, and / or configuration determined by space constraints.

[0033] In the heat transfer system 100, the amount of heat transfer facilitated depends at least in part upon the joining arrangement of the flange 134 and the flange 136 with the barrier 132. If all surfaces are flat and smooth, the joining arrangement can be made tight by fasteners (not shown in FIG. 4) such that sufficient conductive contact facilitates suitable heat transfer. In an embodiment, a thermal interface material (not shown in FIG. 4, described below) can be interposed between one or both flanges and the barrier 132 to enhance the thermal coupling between the flanges and the barrier 132.

[0034] The barrier 132 can be described as generally planar with a first surface 132A and a second surface 132B. The first surface 132A can be on the hot side 126 of the heat transfer system and the second surface 132B being on the cold side 128 of the heat transfer system. By “planar” is not meant perfectly planar or meant to denote any degree of flatness. Rather, by “planar” is meant that the barrier 132 can take the generally smooth surface configuration of, for example, a portion of a wall of a crewed cabin pressure vessel of a space vehicle. As such, “planar” can include a degree of curvature for the barrier 132. As described herein, portions of the barrier 132 can be described as “locally planar” and in locally planar locations the barrier 132 can have a surface flatness / smoothness matching that of the flanges of the heat pipes, as described more fully herein. Thus, in use, the heat transfer system can be utilized on barriers 132 that are portions of the sides of space vehicles that exhibit curvature, but which themselves have a relatively greater degree of flatness. In an embodiment, the thickness T1 of the barrier 132 can be generally equal to the thickness of the outer wall or outer panel of a space vehicle.

[0035] For a barrier 132 sufficiently thick, the flanges 134, 136 of the heat pipes 110, 112, respectively, can be screwed or bolted into the first and second surfaces of the barrier 132 without penetrating both exterior surfaces of the barrier 132. In some embodiments, the barrier 132 may be too thin to accommodate fasteners sufficient to provide the normal force of the attached components required for desired heat transfer across the barrier. If the 132132 is relatively thin, such that suitable and sufficient mounting screws or bolts would completely penetrate the barrier 132, the barrier can be modified to accommodate screws or bolts, as disclosed herein.

[0036] Referring now to FIGS. 5-9, there is shown a heat transfer system 200 in which the barrier 232 is relatively thin, with a first surface 232A and a second surface 232B (as depicted in FIG. 7). By “relatively thin” is meant that the barrier thickness T1, or average thickness, exclusive of the protrusions described herein, is such that sufficient attachment by screwing or bolting of a heat pipe via its flanges could result in the screw or bolt penetrating the barrier. In an embodiment, the barrier is part of the outer wall of a spacecraft. In an embodiment, the barrier is part of the outer wall of a pressurized crew cabin of a manned spacecraft. In an embodiment, the barrier is between about 0.01 and about 10 mm in thickness. In an embodiment, the barrier is between about 0.20 and about 2.5 mm in thickness. In an embodiment, the barrier is between about 0.25 and about 1.0 mm in thickness. In an embodiment, the barrier is aluminum. In an embodiment, the barrier is titanium.

[0037] For purposes of description, components of the heat transfer system can be described with reference to an imaginary system axis A that can be generally centrally disposed in a plane of the barrier 232 at the location of the heat transfer system 200. A first heat pipe 210 with one or more first flanges 234 for connection is on the relatively hot side 226 of the heat transfer system 200, and a second heat pipe 220 with one or more second flanges 236 is on the relatively cold side 228 of the heat transfer system 200. In the illustrated embodiment, the first heat pipe 210 is straight with a longitudinal axis HP1A generally parallel to and directionally aligned with the system axis A. Likewise, the second heat pipe 220 is straight with a longitudinal axis HP2A generally parallel to and directionally aligned with the system axis A and the longitudinal axis HP1A.

[0038] For all the heat transfer systems disclosed herein, the method of operation can be illustrated in the configuration of two heat pipes of the heat transfer system 200. The heat transfer system can be configured such that the condenser portion of the first heat pipe is disposed near the evaporator portion of the second heat pipe. For example, as depicted in FIG. 5, the first heat pipe 210 can have an evaporator portion 270 in fluid communication with a condenser portion 272. The condenser portion 272 of the first heat pipe 210 is mounted adjacent to the evaporator portion 274 of the second heat pipe 220 for operational conductive heat transfer through the barrier 232. The evaporator portion 274 of the second heat pipe 220 is in fluid communication with the condenser portion 276 of the second heat pipe 210. In the illustrated configuration, it is understood that heat flows from the hot side of the heat transfer system generally as depicted by dashed arrow 280 to the cold side of the heat transfer system.

[0039] The heat transfer system 200 can be utilized in a crewed spacecraft to transfer heat from a pressurized crew cabin on the relatively hot side of the heat transfer system to outer space on the relatively cold side of the heat transfer system. In the example heat transfer system 200, the barrier 232 can be a portion of the wall of the pressure vessel, i.e., the crew cabin, of the spacecraft. When used as a heat transfer system 200 for space flight applications, it is beneficial to join the heat pipes to the barrier 232 without penetration of the barrier 232.

[0040] To accommodate fasteners without penetrations, the barrier 232 can have one or more penetration-free protrusions 240. The protrusions 240 can be deformations of the barrier 232 out of the local plane of the barrier 232. As discussed more fully below, the protrusions 240 can be described as bosses with blind fastening portions, such as internal threads, in the unpenetrated barrier 232. In an embodiment, the protrusions 240 can be configured with internal threads in a pattern to receive a similar pattern of mating externally threaded fasteners, e.g., bolts 242. The number, size, and spacing of the protrusions 240 in the pattern of protrusions 240 can be predetermined as desired for a balance of thermal conductivity and cost or weight.

[0041] Continuing to refer to FIG. 5, and with reference to FIGS. 6-10, in the heat transfer system 200, the bolts 242 attach the flange(s) of the heat pipes to the barrier 232 by being tightened onto the internal threads of protrusions 240. For example, in FIG. 5, bolt 242A attaches via a through-hole in flange 236 to the barrier 232 via internal threads in the protrusion 240A, drawing the flange 236 tightly to the surface of the barrier 232. The protrusions 240 can be formed by any suitable process, including by machining, molding, cold deformation, or hot deformation of the material of the barrier 232. In an embodiment the barrier 232 is machined out of metal. The machining process includes forming the barrier 232 to any shape or curvature required for its operational configuration, and the forming, e.g., by drilling, of holes in a quantity and pattern desired for the size and number of flanges on the heat pipes. For each hole, an internally threaded, machined boss can be welded onto the barrier 232 to make a blind hole fastening connection. Once all the bosses are welded at hole sites, the barrier 232 is a penetration-free barrier.

[0042] Referring now to FIGS. 6 and 7, there is shown a representative embodiment of the barrier 232 of the heat transfer system 200. As shown, the barrier 232 in the location of the heat transfer system 200 can be generally planar with a first, hot side surface 232A and a second, cold side surface 232B. In use, the heat transfer system 200 can utilize barriers 232 that are portions of the sides of space vehicles that exhibit curvature. The barrier 232 can be a portion of an outer wall, skin, or panel of the crew cabin of a space vehicle. In an embodiment, the thickness T1 of the barrier 232 can be generally equal to the thickness of the outer wall or outer panel of a space vehicle.

[0043] The system central axis A can generally divide the barrier 232 in the location of the heat transfer system 200 into two portions. In the embodiment shown the two portions are symmetric halves. On a first half 232CA there is a first row of protrusions having a plurality of protrusions 240 generally equally spaced in a line parallel to the system central axis A. Likewise, on a second half 232B there is a second row of protrusions having a plurality of protrusions 240 generally equally spaced in a line parallel to the system central axis A. In general, it is not necessary that the protrusions 240 be in rows or otherwise in an ordered pattern. All that is necessary is that at least some of the corresponding holes in the flanges of the heat pipes line up with the protrusions so that fasteners, e.g., bolts or screws, can be disposed through the flanges and fastened to the protrusions via, e.g., internal threads. While bolts are illustrated in the example embodiments herein, it is recognized that any suitable fasteners can be utilized, including blind rivets, quick disconnect fasteners, pressure connections, quarter-turn connections, weldments, as well as glues, adhesives, and magnetic connections.

[0044] As shown in FIG. 7, a first portion 240C of the protrusions 240 extend out of the plane of the barrier 232 on the hot side 226 of the barrier 232, and a second portion 240D of the protrusions 240 extend out of the plane of the barrier 232 on the cold side 228 of the barrier 232. In general, the first portion 240C can have the same number, size, and spacing of protrusions 240 as exist on the second portion 240D. However, any number, spacing and pattern of protrusions can be employed as desired for heat conductive requirements of a heat transfer system.

[0045] As shown in FIGS. 6 and 7, the protrusions 240 can be configured as bosses welded to the barrier 232 with an interior defining a fastener-receiving opening 244, which can be a blind hole, and which can be internally threaded for receiving threaded fasteners. In the illustrated embodiment, the first portion 240C of protrusions 240 serve as attachment locations for the second heat pipe 220 and the second portion 240D of protrusions 240 can serve as attachment locations for the first heat pipe 210.

[0046] The first portion 240C of protrusions 240 and the second portion 240D of protrusions 240 can each be patterned and spaced to accommodate the flanges of the heat pipes. For example, referring to the second portion 240D of protrusions 240, as indicated by the dashed rectangles in FIG. 6, the protrusions 240 are grouped and spaced to accommodate the flanges of the heat pipes. As shown, a first group 246A of protrusions 240 can be spaced in a group suitable for receiving fasteners for a first flange of a heat pipe and a second group 246B of protrusions 240 can be spaced in a group suitable for receiving fasteners for a second flange of a heat pipe (as discussed more fully below). In general, any number of protrusions and any number of groups of protrusions can be employed in the heat transfer system 200. However, for a given number and pattern of protrusions, the groups of protrusions can be spaced a protrusion distance PS apart, as indicated in FIG. 7 for groups 246A and 246B. As discussed below, the separation distance PS accommodates the flanges of the heat pipes mounted to the barrier 232. In general, the flanges of the heat pipes are “nested” between groups of protrusions in the relatively planar portions of the barrier 232.

[0047] While the description herein is in terms of flanges (plural), it is noted that the same benefits of heat transfer can be achieved with a single flange, including a single flange being shaped to be effectively two or more extending flanges as depicted on the flange 534 of the first heat pipe 510 in FIG. 15, or multiple flanges can be attached to the sides of the heat pipe, as depicted on the second heat pipe 520 of FIG. 15. In any configuration, whether one flange or many, the conductive “footprint” of each heat pipe takes the shape of the flange(s) and / or the heat pipe body. In the embodiment illustrated in FIGS. 5-10 and FIG. 15, for example, the conductive “footprint” is indicated by the shape of the thermal interface material 560, discussed more fully below. Thus, whether one flange or many, the heat transfer system can have the general appearance of, and be described as having, two flanges as illustrated in the heat transfer system 200 of FIGS. 5-10.

[0048] The pattern and spacing of the protrusions and groups of protrusions in relation to the heat pipe flanges can be better understood with reference to FIGS. 8-10. As depicted in FIG. 8, the first heat pipe 210 can have two flanges 234, each joined to the barrier 232 by four fasteners, e.g., bolts 242. In the illustrated embodiment, four hex-head bolts match the spacing of the of the protrusions 240 for each group of protrusions, 246A and 246B, as shown in FIG. 6. As depicted in FIG. 9, a similar configuration applies for second heat pipe 220. In general, the placement of flanges nested in within protrusions can be as “tight” as possible to reduce lateral thermal conduction distances in the barrier 232.

[0049] Each flange 234 portion extending from the heat pipe can be generally rectangular shaped with a flange length dimension FL measured generally parallel to imaginary axis A and a flange width dimension FW measured generally orthogonal to imaginary axis A. In the illustrated embodiment, first heat pipe 210 is joined to two flanges 234 extending from the heat pipe, but in general each heat pipe can have one or more discrete flanges joined to the heat pipe. Also, as discussed above, the two flanges 234 shown in FIG. 8 can be unitary with a portion that takes the shape of the heat pipe / barrier interface, such that while described as two flanges, the system can be described as having one flange with four flange extensions. For descriptive purposes, such a flange / extension arrangement is shown in more detail as the flange 534 of first heat pipe 510 in FIG. 15.

[0050] As indicated in FIG. 9, for proper operation, flanges are disposed to be secured to the barrier 232 between groups of protrusions. As such, the flange length dimension FL is less than the protrusion spacing dimension PS, i.e., FL<PS. In this manner, each flange can be joined, such as by threaded fasteners, into relatively flat, tight surface contact with the barrier 232 to achieve conductive heat flow across the barrier 232.

[0051] As indicated in FIGS. 9-10, the protrusions 240 facilitate fastening to the barrier 232 without penetration of the barrier 232. That is, the protrusions 240 are integral with, unitary with, or otherwise made as a unit with, the barrier 232, such that the barrier 232 remains an intact, penetration-free panel onto which the heat pipes are joined with fasteners, such as bolts 242, to make the heat transfer system 200. The configuration disclosed herein is important for applications such as spacecraft, where penetrations of the spacecraft outer surface for pumped fluid thermal control are potential sites of pressure loss that can be catastrophic. Thus, unlike pumped fluid systems, the heat transfer system 200 can be described a penetration-free system utilizing a barrier 232 having joined on each side a heat pipe.

[0052] Referring now to FIGS. 11-12, there is illustrated the barrier 332 of a heat transfer system 300 that differs from the heat transfer system 200 in that the thickness T2 of the barrier 332 is greater than a surrounding thickness T1 of, for example, the wall of a spacecraft. Because the heat pipes and their other attached components have mass that may be at least partially reacted through a crew cabin pressure vessel wall during launch loads, a thicker barrier 332 in the region of the heat transfer system can be beneficial. The thicker barrier 332 can have rounded perimeters to minimize stress concentrations. In the embodiment illustrated, the thickness T2 of the barrier 332 is greater than the thickness T1 with additional conductive material 350 on one surface of the barrier 332. As depicted, additional material 350 renders T2<T1 with an increase in thickness on the cold side 328 of the heat transfer system 300, while the surface of the barrier 332 on the cold side 326 remains unchanged. In all other respects, the heat transfer system 300 can be identical to that described for heat transfer system 200 above.

[0053] Referring now to FIGS. 13-14, there is illustrated the barrier 432 of a heat transfer system 400 that differs from the heat transfer system 200 in that the thickness T3 of the barrier 432 is greater than a surrounding thickness T1 of, for example, the wall of a spacecraft. The additional thickness serves the same beneficial purpose as described above for barrier 332 in heat transfer system 300. In the embodiment illustrated, the thickness T3 of the barrier 432 is greater than the thickness T1 with additional conductive material 350 on both surfaces of the barrier 432. As depicted, additional material 450 on one surface and additional material 452 on the other surface renders T3<T1 with an increase in thickness on the cold side 428 and hot side 426 of the heat transfer system 400. In all other respects, the heat transfer system 400 can be identical to that described for heat transfer system 200 above.

[0054] Referring now to the exploded view of FIG. 15, there is illustrated a heat transfer system 500 that differs from the heat transfer systems 200, 300 and / or 400 in that a thermal interface material 560 is disposed between at least one of the heat pipes 510, 520 (and their respective flange(s)) and the barrier 532. As depicted, a thermal interface material 560 is disposed between one or both the first heat pipe 510 (and flanges) and the second heat pipe 520 (and flanges). As depicted, the thermal interface material 560 can be shaped for the maximum conductive “footprint,” and can be a shape that covers all portions of the heat pipes and flanges in contact with the barrier 532. The thermal interface material 560 can be any of known materials suitable for the environment of the heat transfer system 500, and can include dielectric pads, heat spreaders, thermal compounds, thermal gels, thermal tapes, phase change materials, gap filler pads, thermal greases, curable compounds, and combinations thereof. In all other respects, the heat transfer system 400 can be identical to that for heat transfer systems 200, 300 or 400, described above.

[0055] A method of use is illustrated in an application of a heat transfer system in FIGS. 16 and 17. Depicted in FIGS. 16 and 17 is a representative space vehicle 600. The space vehicle, shown in representative component parts, can be a pressurized vessel utilized as the crew cabin of a spacecraft. Current heat transfer systems of current space vehicles utilize pumped fluid in piping utilizing through-holes in the walls of the space vehicle, such as those circled at 660. In contrast, in a method of the current disclosure, one or more heat transfer systems can be employed on a space vehicle without penetrations in the wall of the space vehicle.

[0056] As shown in FIG. 16, multiple barriers, e.g., barriers 232 can be disposed in multiple places on the space vehicle. As shown, four barriers 232, indicated as 232E-232H, being configured with protrusions can be integrated into the wall of a space vehicle. In use, none, one, or all the barriers can be utilized as heat transfers systems. When not used, the barriers 232 simply form part of the pressure vessel due to the fact that they are penetration-free. In FIG. 17 two of the barriers have attached thereto the heat pipes as described herein to render two heat transfer systems e.g., one or more of heat transfer systems 200, 300, 400 or 500, on the space vehicle 600. Thus, one of the benefits of the penetration-free heat transfer systems of the present disclosure is the capability to build in flexible functionality with respect to potential heat transfer systems to optionally be used on a space vehicle.

[0057] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

Examples

Embodiment Construction

[0025]Embodiments of the disclosed development, its various features, and the advantageous details thereof, are explained more fully concerning the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure what is being disclosed. Examples may be provided, and when so provided are intended merely to facilitate an understanding of how the invention may be practiced and to further enable those of skill in the art to practice its various embodiments. Accordingly, examples should not be construed as limiting the scope of what is disclosed and otherwise claimed.

[0026]Referring to FIG. 1 there is shown a representative heat pipe 10. The heat pipe 10 has an evaporator portion 12 and a condenser portion 14 separated by an adiabatic section 16. Heat 18 to be moved is transferred into the heat pipe 10 in the evaporator portion 12 ...

GOVERNMENT INTEREST

[0001] The invention described herein may be manufactured and used by or for the Government of the United States for all government purposes without the payment of any royalty.FIELD OF THE INVENTION

[0002] The embodiments herein generally relate to heat transfer in space vehicles.BACKGROUND

[0003] Existing spaceflight thermal control systems utilize pumped fluid loops. Pumped fluid loops for spaceflight thermal control systems utilize pipes to transport fluid to move heat from the crew cabin to exterior radiators. The pipes must traverse the wall of the spacecraft, including in the case of crewed spacecraft, the crew cabin, i.e., the pressure vessel, twice to close the loop. Typical pumped fluid loop designs include a redundant pumped fluid loop for a total of four pressure vessel penetrations. Human spaceflight thermal control subsystems for space capsules (Gemini, Apollo, Soyuz, Dragon, Starliner, Russian space station modules) tend to be 1-loop pumped fluid loop systems and human spaceflight thermal control systems for larger systems (Shuttle, ISS) tend to be 2-loop pumped fluid loop systems. For either 1-loop or 2-loop systems, the pumped fluid loop penetrates the pressure vessel and, therefore, becomes part of the crew cabin's hermeticity. The penetrations for the pumped fluid loop must contain the crew cabin's pressure and a failure is tantamount to a crew cabin pressure vessel leak.

[0004] Additionally, pumped fluid loop systems require a fluid that has sufficient thermal performance, good thermal performance characteristics, does not pose risks to the hermeticity of the PFL when cooled to its minimum operating temperature and is safe for being near humans. These three constraints are difficult to satisfy. Such designs from early in the space ages usually had to cut corners and accept unsafe fluids (e.g., in the Gemini spacecraft) or accept fluids with marginal safety and low temperature operation (e.g., the Apollo and Soyuz spacecrafts). Pumped fluid loop designs today have access to a wider array of fluid choices, but the problem is still over constrained such that fluids are often safe but have marginal performance.

[0005] A continuing, unaddressed need exists for systems and methods to achieve a human spaceflight thermal control system that operates without any penetrations in the crew cabin.

[0006] A continuing, unaddressed need exists a thermal control system in a spacecraft in which human safe fluids are inside and high performance, but potentially dangerous, fluids are kept outside the spacecraft.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The embodiments herein will be better understood from the following detailed description of the drawings, in which:

[0008] FIG. 1 is a representative heat pipe;

[0009] FIG. 2 is a cross section of a representative heat pipe;

[0010] FIG. 3 is a cross section of a representative heat pipe;

[0011] FIG. 4 is a diagram depicting a heat transfer system of the current disclosure;

[0012] FIG. 5 is a diagram depicting a heat transfer system of the current disclosure

[0013] FIG. 6 is a front view of an example barrier;

[0014] FIG. 7 is a side view of an example barrier;

[0015] FIG. 8 is a front view of an example heat transfer system;

[0016] FIG. 9 is a side view of an example heat transfer system;

[0017] FIG. 10 is a top view of an example heat transfer system;

[0018] FIG. 11 is a front view of an example barrier;

[0019] FIG. 12 is a side view of an example barrier;

[0020] FIG. 13 is a front view of an example barrier;

[0021] FIG. 14 is a side view of an example barrier;

[0022] FIG. 15 is an exploded view of an example heat transfer system;

[0023] FIG. 16 is an example method of use of a heat transfer system on a space vehicle; and

[0024] FIG. 17 is an example method of use of a heat transfer system on a space vehicle.DETAILED DESCRIPTION

[0025] Embodiments of the disclosed development, its various features, and the advantageous details thereof, are explained more fully concerning the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure what is being disclosed. Examples may be provided, and when so provided are intended merely to facilitate an understanding of how the invention may be practiced and to further enable those of skill in the art to practice its various embodiments. Accordingly, examples should not be construed as limiting the scope of what is disclosed and otherwise claimed.

[0026] Referring to FIG. 1 there is shown a representative heat pipe 10. The heat pipe 10 has an evaporator portion 12 and a condenser portion 14 separated by an adiabatic section 16. Heat 18 to be moved is transferred into the heat pipe 10 in the evaporator portion 12 to cause a phase change in an internally disposed heat pipe fluid (not shown in FIG. 1), e.g., vaporization to a vapor phase, within the heat pipe 10. Heat 20 to be released exits at the condenser portion 14 where the fluid undergoes the reverse phase change, e.g., condensation back into a liquid. The liquid is then transported back, such as wicking by capillary transport, to the evaporator portion of the heat pipe 10 to absorb additional heat.

[0027] Representative heat pipe configurations are shown in cross section in FIGS. 2 and 3. As depicted in FIG. 2, which is a view of Section 2-2 at the evaporator portion 12 of the heat pipe 10 of FIG. 1, a heat pipe can have internally extending axial ridges 22 defining axial grooves 24. To achieve wicking from the condenser portion 12 to the evaporator portion 14, the heat pipe 10 relies on capillary fluid flow. As depicted in FIG. 2, which is a view of Section 2-2 at the evaporator portion 12 of the flexible heat pipe 10 of FIG. 1 but can be identical to that of the condenser portion 14, the flexible heat pipe 10 can have internally extending axial ridges 22 defining axial grooves 24. The axial ridges and grooves can be oriented in a longitudinal direction generally parallel to a central axis of the heat pipe and can be manufactured according to known means, including by machining the interior of the evaporator and condenser portions. The grooves can be sized and shaped according to known means to serve as capillary channels suitable to move the fluid 26 via capillary action from the condenser portion 14 to the evaporator portion 12.

[0028] The fluid 26 is disposed in the interior portion 28 of the heat pipe 10 and is in fluid communication with the evaporator portion 12 and the condenser portion 14. Upon heat 18 being transferred into the heat pipe 10 at the evaporator portion 12, the fluid 26, which can be water, for example, vaporizes in the interior portion 28 of the heat pipe 10. At the condenser portion 14, the fluid condenses back to a fluid as it releases the transported heat out of the heat pipe and is wicked, e.g., by capillary action, in the axial grooves 24 defined by the axial ridges 22. As depicted in the heat pipe in FIG. 2, a cylindrical-shaped heat pipe can transfer heat 18 substantially uniformly over the entire exterior surface of the heat pipe 10.

[0029] The heat pipe 10 shown in FIG. 3 operates in substantially the same manner as that shown in FIG. 2, with the difference being the heat pipe 10 includes a flange 28. The flange 28 can be integral with, unitary, or otherwise be joined in heat-conductive relationship to, the heat pipe 10 to provide addition heat transfer surface area. The heat pipe 10 can have more than one flange 28, and the flange 28 can extend the length of the heat pipe 10, or a portion of the length. In the configuration of a heat pipe 10 having a flange 28, the flange 28 can be in heat-conductive contact with a heat source, such that heat 18 transfer is non-uniform, with relatively more heat 18 being transferred via the flange 28 into (or out of) the heat pipe 10.

[0030] Referring now to FIG. 4 there is disclosed a heat transfer system 100 involving two heat pipes. While two heat pipes are illustrated, it is understood that the heat transfer can be between two pumped fluid loops, two solid thermal conductors, and other combinations of heat transfer components. A first heat pipe 110 is joined in a thermally conductive relationship with a second heat pipe 120 across a solid barrier. By “solid barrier” is meant a penetration-free barrier in which there are no holes, gaps, or other penetrations through which any gas, fluid, vapor, or solid can traverse through the barrier. For descriptive purposes, the solid barrier of the present disclosure will be referred to simply as a “barrier” and is understood in the embodiments herein as a portion of a spacecraft outer wall that separates a crewed cabin from outer space. In the heat transfer system 100 illustrated in FIG. 4, a barrier 132 separates a relatively hot side 126 of the heat transfer system 100 from a relatively cold side 128. For descriptive purposes in the illustrated embodiment, the first heat pipe 110 can be considered on the relatively hot side 126 of the heat transfer system 100, and the second heat pipe can be considered on the relatively cold side 128 of the heat transfer system 100. While heat can potentially flow in either direction depending on thermal conditions, in the configuration described, heat flows in the direction indicated by arrow 130. The two heat pipes are each configured to be joined in a heat-conductive relationship at the barrier 132 for conductive heat transfer through the barrier 132. Joining to the barrier 132 can be by any suitable means that does not penetrate the barrier 132 and which effects suitable normal forces to facilitate sufficient conductive heat transfer across the barrier 132. Examples of joining include glueing, bonding, adhering, bolting, screwing, and combinations thereof.

[0031] The first heat pipe 110 has an evaporator portion 112 in fluid communication with a condenser portion 114, as described above with respect to FIGS. 1 and 2. In addition, the first heat pipe 110 has a flange 134 joined in heat-conductive relationship with both the first heat pipe 110 and the barrier 132. The barrier 132 can be a panel, wall, or other structure tending to prevent heat transfer from the relatively hot side 126 to the relatively cold side 128 of the heat transfer system 100. In like manner, the second heat pipe 120 has an evaporator portion 122 in fluid communication with condenser portion 124, as described above with respect to FIGS. 1 and 2. The second heat pipe 120 has a flange 136 joined in heat-conductive relationship with both the second heat pipe 120 and the barrier 132.

[0032] In an embodiment the heat pipes and flanges can be made of metal, e.g., aluminum, titanium, and / or stainless steel, and the flange of each heat pipe can be unitary with the heat pipe, or separately joined, such as by welding. The heat pipes can be generally cylindrically shaped and can be any length, diameter, and shape suitable for the desired heat transfer rate. The heat pipes can be generally straight along their entire length, or curved along a portion of their length, as shown in FIG. 4. The configuration of size and shape of the heat pipes can be determined to achieve the desired heat transfer, and / or configuration determined by space constraints.

[0033] In the heat transfer system 100, the amount of heat transfer facilitated depends at least in part upon the joining arrangement of the flange 134 and the flange 136 with the barrier 132. If all surfaces are flat and smooth, the joining arrangement can be made tight by fasteners (not shown in FIG. 4) such that sufficient conductive contact facilitates suitable heat transfer. In an embodiment, a thermal interface material (not shown in FIG. 4, described below) can be interposed between one or both flanges and the barrier 132 to enhance the thermal coupling between the flanges and the barrier 132.

[0034] The barrier 132 can be described as generally planar with a first surface 132A and a second surface 132B. The first surface 132A can be on the hot side 126 of the heat transfer system and the second surface 132B being on the cold side 128 of the heat transfer system. By “planar” is not meant perfectly planar or meant to denote any degree of flatness. Rather, by “planar” is meant that the barrier 132 can take the generally smooth surface configuration of, for example, a portion of a wall of a crewed cabin pressure vessel of a space vehicle. As such, “planar” can include a degree of curvature for the barrier 132. As described herein, portions of the barrier 132 can be described as “locally planar” and in locally planar locations the barrier 132 can have a surface flatness / smoothness matching that of the flanges of the heat pipes, as described more fully herein. Thus, in use, the heat transfer system can be utilized on barriers 132 that are portions of the sides of space vehicles that exhibit curvature, but which themselves have a relatively greater degree of flatness. In an embodiment, the thickness T1 of the barrier 132 can be generally equal to the thickness of the outer wall or outer panel of a space vehicle.

[0035] For a barrier 132 sufficiently thick, the flanges 134, 136 of the heat pipes 110, 112, respectively, can be screwed or bolted into the first and second surfaces of the barrier 132 without penetrating both exterior surfaces of the barrier 132. In some embodiments, the barrier 132 may be too thin to accommodate fasteners sufficient to provide the normal force of the attached components required for desired heat transfer across the barrier. If the 132132 is relatively thin, such that suitable and sufficient mounting screws or bolts would completely penetrate the barrier 132, the barrier can be modified to accommodate screws or bolts, as disclosed herein.

[0036] Referring now to FIGS. 5-9, there is shown a heat transfer system 200 in which the barrier 232 is relatively thin, with a first surface 232A and a second surface 232B (as depicted in FIG. 7). By “relatively thin” is meant that the barrier thickness T1, or average thickness, exclusive of the protrusions described herein, is such that sufficient attachment by screwing or bolting of a heat pipe via its flanges could result in the screw or bolt penetrating the barrier. In an embodiment, the barrier is part of the outer wall of a spacecraft. In an embodiment, the barrier is part of the outer wall of a pressurized crew cabin of a manned spacecraft. In an embodiment, the barrier is between about 0.01 and about 10 mm in thickness. In an embodiment, the barrier is between about 0.20 and about 2.5 mm in thickness. In an embodiment, the barrier is between about 0.25 and about 1.0 mm in thickness. In an embodiment, the barrier is aluminum. In an embodiment, the barrier is titanium.

[0037] For purposes of description, components of the heat transfer system can be described with reference to an imaginary system axis A that can be generally centrally disposed in a plane of the barrier 232 at the location of the heat transfer system 200. A first heat pipe 210 with one or more first flanges 234 for connection is on the relatively hot side 226 of the heat transfer system 200, and a second heat pipe 220 with one or more second flanges 236 is on the relatively cold side 228 of the heat transfer system 200. In the illustrated embodiment, the first heat pipe 210 is straight with a longitudinal axis HP1A generally parallel to and directionally aligned with the system axis A. Likewise, the second heat pipe 220 is straight with a longitudinal axis HP2A generally parallel to and directionally aligned with the system axis A and the longitudinal axis HP1A.

[0038] For all the heat transfer systems disclosed herein, the method of operation can be illustrated in the configuration of two heat pipes of the heat transfer system 200. The heat transfer system can be configured such that the condenser portion of the first heat pipe is disposed near the evaporator portion of the second heat pipe. For example, as depicted in FIG. 5, the first heat pipe 210 can have an evaporator portion 270 in fluid communication with a condenser portion 272. The condenser portion 272 of the first heat pipe 210 is mounted adjacent to the evaporator portion 274 of the second heat pipe 220 for operational conductive heat transfer through the barrier 232. The evaporator portion 274 of the second heat pipe 220 is in fluid communication with the condenser portion 276 of the second heat pipe 210. In the illustrated configuration, it is understood that heat flows from the hot side of the heat transfer system generally as depicted by dashed arrow 280 to the cold side of the heat transfer system.

[0039] The heat transfer system 200 can be utilized in a crewed spacecraft to transfer heat from a pressurized crew cabin on the relatively hot side of the heat transfer system to outer space on the relatively cold side of the heat transfer system. In the example heat transfer system 200, the barrier 232 can be a portion of the wall of the pressure vessel, i.e., the crew cabin, of the spacecraft. When used as a heat transfer system 200 for space flight applications, it is beneficial to join the heat pipes to the barrier 232 without penetration of the barrier 232.

[0040] To accommodate fasteners without penetrations, the barrier 232 can have one or more penetration-free protrusions 240. The protrusions 240 can be deformations of the barrier 232 out of the local plane of the barrier 232. As discussed more fully below, the protrusions 240 can be described as bosses with blind fastening portions, such as internal threads, in the unpenetrated barrier 232. In an embodiment, the protrusions 240 can be configured with internal threads in a pattern to receive a similar pattern of mating externally threaded fasteners, e.g., bolts 242. The number, size, and spacing of the protrusions 240 in the pattern of protrusions 240 can be predetermined as desired for a balance of thermal conductivity and cost or weight.

[0041] Continuing to refer to FIG. 5, and with reference to FIGS. 6-10, in the heat transfer system 200, the bolts 242 attach the flange(s) of the heat pipes to the barrier 232 by being tightened onto the internal threads of protrusions 240. For example, in FIG. 5, bolt 242A attaches via a through-hole in flange 236 to the barrier 232 via internal threads in the protrusion 240A, drawing the flange 236 tightly to the surface of the barrier 232. The protrusions 240 can be formed by any suitable process, including by machining, molding, cold deformation, or hot deformation of the material of the barrier 232. In an embodiment the barrier 232 is machined out of metal. The machining process includes forming the barrier 232 to any shape or curvature required for its operational configuration, and the forming, e.g., by drilling, of holes in a quantity and pattern desired for the size and number of flanges on the heat pipes. For each hole, an internally threaded, machined boss can be welded onto the barrier 232 to make a blind hole fastening connection. Once all the bosses are welded at hole sites, the barrier 232 is a penetration-free barrier.

[0042] Referring now to FIGS. 6 and 7, there is shown a representative embodiment of the barrier 232 of the heat transfer system 200. As shown, the barrier 232 in the location of the heat transfer system 200 can be generally planar with a first, hot side surface 232A and a second, cold side surface 232B. In use, the heat transfer system 200 can utilize barriers 232 that are portions of the sides of space vehicles that exhibit curvature. The barrier 232 can be a portion of an outer wall, skin, or panel of the crew cabin of a space vehicle. In an embodiment, the thickness T1 of the barrier 232 can be generally equal to the thickness of the outer wall or outer panel of a space vehicle.

[0043] The system central axis A can generally divide the barrier 232 in the location of the heat transfer system 200 into two portions. In the embodiment shown the two portions are symmetric halves. On a first half 232CA there is a first row of protrusions having a plurality of protrusions 240 generally equally spaced in a line parallel to the system central axis A. Likewise, on a second half 232B there is a second row of protrusions having a plurality of protrusions 240 generally equally spaced in a line parallel to the system central axis A. In general, it is not necessary that the protrusions 240 be in rows or otherwise in an ordered pattern. All that is necessary is that at least some of the corresponding holes in the flanges of the heat pipes line up with the protrusions so that fasteners, e.g., bolts or screws, can be disposed through the flanges and fastened to the protrusions via, e.g., internal threads. While bolts are illustrated in the example embodiments herein, it is recognized that any suitable fasteners can be utilized, including blind rivets, quick disconnect fasteners, pressure connections, quarter-turn connections, weldments, as well as glues, adhesives, and magnetic connections.

[0044] As shown in FIG. 7, a first portion 240C of the protrusions 240 extend out of the plane of the barrier 232 on the hot side 226 of the barrier 232, and a second portion 240D of the protrusions 240 extend out of the plane of the barrier 232 on the cold side 228 of the barrier 232. In general, the first portion 240C can have the same number, size, and spacing of protrusions 240 as exist on the second portion 240D. However, any number, spacing and pattern of protrusions can be employed as desired for heat conductive requirements of a heat transfer system.

[0045] As shown in FIGS. 6 and 7, the protrusions 240 can be configured as bosses welded to the barrier 232 with an interior defining a fastener-receiving opening 244, which can be a blind hole, and which can be internally threaded for receiving threaded fasteners. In the illustrated embodiment, the first portion 240C of protrusions 240 serve as attachment locations for the second heat pipe 220 and the second portion 240D of protrusions 240 can serve as attachment locations for the first heat pipe 210.

[0046] The first portion 240C of protrusions 240 and the second portion 240D of protrusions 240 can each be patterned and spaced to accommodate the flanges of the heat pipes. For example, referring to the second portion 240D of protrusions 240, as indicated by the dashed rectangles in FIG. 6, the protrusions 240 are grouped and spaced to accommodate the flanges of the heat pipes. As shown, a first group 246A of protrusions 240 can be spaced in a group suitable for receiving fasteners for a first flange of a heat pipe and a second group 246B of protrusions 240 can be spaced in a group suitable for receiving fasteners for a second flange of a heat pipe (as discussed more fully below). In general, any number of protrusions and any number of groups of protrusions can be employed in the heat transfer system 200. However, for a given number and pattern of protrusions, the groups of protrusions can be spaced a protrusion distance PS apart, as indicated in FIG. 7 for groups 246A and 246B. As discussed below, the separation distance PS accommodates the flanges of the heat pipes mounted to the barrier 232. In general, the flanges of the heat pipes are “nested” between groups of protrusions in the relatively planar portions of the barrier 232.

[0047] While the description herein is in terms of flanges (plural), it is noted that the same benefits of heat transfer can be achieved with a single flange, including a single flange being shaped to be effectively two or more extending flanges as depicted on the flange 534 of the first heat pipe 510 in FIG. 15, or multiple flanges can be attached to the sides of the heat pipe, as depicted on the second heat pipe 520 of FIG. 15. In any configuration, whether one flange or many, the conductive “footprint” of each heat pipe takes the shape of the flange(s) and / or the heat pipe body. In the embodiment illustrated in FIGS. 5-10 and FIG. 15, for example, the conductive “footprint” is indicated by the shape of the thermal interface material 560, discussed more fully below. Thus, whether one flange or many, the heat transfer system can have the general appearance of, and be described as having, two flanges as illustrated in the heat transfer system 200 of FIGS. 5-10.

[0048] The pattern and spacing of the protrusions and groups of protrusions in relation to the heat pipe flanges can be better understood with reference to FIGS. 8-10. As depicted in FIG. 8, the first heat pipe 210 can have two flanges 234, each joined to the barrier 232 by four fasteners, e.g., bolts 242. In the illustrated embodiment, four hex-head bolts match the spacing of the of the protrusions 240 for each group of protrusions, 246A and 246B, as shown in FIG. 6. As depicted in FIG. 9, a similar configuration applies for second heat pipe 220. In general, the placement of flanges nested in within protrusions can be as “tight” as possible to reduce lateral thermal conduction distances in the barrier 232.

[0049] Each flange 234 portion extending from the heat pipe can be generally rectangular shaped with a flange length dimension FL measured generally parallel to imaginary axis A and a flange width dimension FW measured generally orthogonal to imaginary axis A. In the illustrated embodiment, first heat pipe 210 is joined to two flanges 234 extending from the heat pipe, but in general each heat pipe can have one or more discrete flanges joined to the heat pipe. Also, as discussed above, the two flanges 234 shown in FIG. 8 can be unitary with a portion that takes the shape of the heat pipe / barrier interface, such that while described as two flanges, the system can be described as having one flange with four flange extensions. For descriptive purposes, such a flange / extension arrangement is shown in more detail as the flange 534 of first heat pipe 510 in FIG. 15.

[0050] As indicated in FIG. 9, for proper operation, flanges are disposed to be secured to the barrier 232 between groups of protrusions. As such, the flange length dimension FL is less than the protrusion spacing dimension PS, i.e., FL<PS. In this manner, each flange can be joined, such as by threaded fasteners, into relatively flat, tight surface contact with the barrier 232 to achieve conductive heat flow across the barrier 232.

[0051] As indicated in FIGS. 9-10, the protrusions 240 facilitate fastening to the barrier 232 without penetration of the barrier 232. That is, the protrusions 240 are integral with, unitary with, or otherwise made as a unit with, the barrier 232, such that the barrier 232 remains an intact, penetration-free panel onto which the heat pipes are joined with fasteners, such as bolts 242, to make the heat transfer system 200. The configuration disclosed herein is important for applications such as spacecraft, where penetrations of the spacecraft outer surface for pumped fluid thermal control are potential sites of pressure loss that can be catastrophic. Thus, unlike pumped fluid systems, the heat transfer system 200 can be described a penetration-free system utilizing a barrier 232 having joined on each side a heat pipe.

[0052] Referring now to FIGS. 11-12, there is illustrated the barrier 332 of a heat transfer system 300 that differs from the heat transfer system 200 in that the thickness T2 of the barrier 332 is greater than a surrounding thickness T1 of, for example, the wall of a spacecraft. Because the heat pipes and their other attached components have mass that may be at least partially reacted through a crew cabin pressure vessel wall during launch loads, a thicker barrier 332 in the region of the heat transfer system can be beneficial. The thicker barrier 332 can have rounded perimeters to minimize stress concentrations. In the embodiment illustrated, the thickness T2 of the barrier 332 is greater than the thickness T1 with additional conductive material 350 on one surface of the barrier 332. As depicted, additional material 350 renders T2<T1 with an increase in thickness on the cold side 328 of the heat transfer system 300, while the surface of the barrier 332 on the cold side 326 remains unchanged. In all other respects, the heat transfer system 300 can be identical to that described for heat transfer system 200 above.

[0053] Referring now to FIGS. 13-14, there is illustrated the barrier 432 of a heat transfer system 400 that differs from the heat transfer system 200 in that the thickness T3 of the barrier 432 is greater than a surrounding thickness T1 of, for example, the wall of a spacecraft. The additional thickness serves the same beneficial purpose as described above for barrier 332 in heat transfer system 300. In the embodiment illustrated, the thickness T3 of the barrier 432 is greater than the thickness T1 with additional conductive material 350 on both surfaces of the barrier 432. As depicted, additional material 450 on one surface and additional material 452 on the other surface renders T3<T1 with an increase in thickness on the cold side 428 and hot side 426 of the heat transfer system 400. In all other respects, the heat transfer system 400 can be identical to that described for heat transfer system 200 above.

[0054] Referring now to the exploded view of FIG. 15, there is illustrated a heat transfer system 500 that differs from the heat transfer systems 200, 300 and / or 400 in that a thermal interface material 560 is disposed between at least one of the heat pipes 510, 520 (and their respective flange(s)) and the barrier 532. As depicted, a thermal interface material 560 is disposed between one or both the first heat pipe 510 (and flanges) and the second heat pipe 520 (and flanges). As depicted, the thermal interface material 560 can be shaped for the maximum conductive “footprint,” and can be a shape that covers all portions of the heat pipes and flanges in contact with the barrier 532. The thermal interface material 560 can be any of known materials suitable for the environment of the heat transfer system 500, and can include dielectric pads, heat spreaders, thermal compounds, thermal gels, thermal tapes, phase change materials, gap filler pads, thermal greases, curable compounds, and combinations thereof. In all other respects, the heat transfer system 400 can be identical to that for heat transfer systems 200, 300 or 400, described above.

[0055] A method of use is illustrated in an application of a heat transfer system in FIGS. 16 and 17. Depicted in FIGS. 16 and 17 is a representative space vehicle 600. The space vehicle, shown in representative component parts, can be a pressurized vessel utilized as the crew cabin of a spacecraft. Current heat transfer systems of current space vehicles utilize pumped fluid in piping utilizing through-holes in the walls of the space vehicle, such as those circled at 660. In contrast, in a method of the current disclosure, one or more heat transfer systems can be employed on a space vehicle without penetrations in the wall of the space vehicle.

[0056] As shown in FIG. 16, multiple barriers, e.g., barriers 232 can be disposed in multiple places on the space vehicle. As shown, four barriers 232, indicated as 232E-232H, being configured with protrusions can be integrated into the wall of a space vehicle. In use, none, one, or all the barriers can be utilized as heat transfers systems. When not used, the barriers 232 simply form part of the pressure vessel due to the fact that they are penetration-free. In FIG. 17 two of the barriers have attached thereto the heat pipes as described herein to render two heat transfer systems e.g., one or more of heat transfer systems 200, 300, 400 or 500, on the space vehicle 600. Thus, one of the benefits of the penetration-free heat transfer systems of the present disclosure is the capability to build in flexible functionality with respect to potential heat transfer systems to optionally be used on a space vehicle.

[0057] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

Examples

Embodiment Construction

[0025]Embodiments of the disclosed development, its various features, and the advantageous details thereof, are explained more fully concerning the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure what is being disclosed. Examples may be provided, and when so provided are intended merely to facilitate an understanding of how the invention may be practiced and to further enable those of skill in the art to practice its various embodiments. Accordingly, examples should not be construed as limiting the scope of what is disclosed and otherwise claimed.

[0026]Referring to FIG. 1 there is shown a representative heat pipe 10. The heat pipe 10 has an evaporator portion 12 and a condenser portion 14 separated by an adiabatic section 16. Heat 18 to be moved is transferred into the heat pipe 10 in the evaporator portion 12 ...

Claims

1. A heat transfer system, comprising,a barrier having a first side and a second side, the first side disposed on a hot side of the heat transfer system and the second side being disposed on the cold side of the heat transfer system;a first plurality of protrusions on the first side of the barrier, and a second plurality of protrusions on the second side of the barrier;a first heat pipe having a first plurality of flanges, the first plurality of flanges being joined on the first side of the barrier by fasteners engaging the first plurality of protrusions; anda second heat pipe having a second plurality of flanges, the second plurality of flanges being joined on the second side of the barrier by fasteners engaging the second plurality of protrusions.

2. The heat transfer system of claim 1, wherein the first plurality of protrusions extend outwardly from the first side of the barrier and the second plurality of protrusions extend outwardly from the second side of the barrier.

3. The heat transfer system of claim 1, wherein first plurality of protrusions and the second plurality of protrusions comprise internally threaded openings and the fasteners are externally threaded.

4. The heat transfer system of claim 1, wherein the barrier is penetration-free.

5. The heat transfer system of claim 1, wherein the barrier is penetration-free and locally planar between the first plurality of protrusions and the second plurality of protrusions.

6. The heat transfer system of claim 1, wherein the barrier is penetration-free and with locally planar regions between the first plurality of protrusions and the second plurality of protrusions and the first plurality of flanges and the second plurality of flanges contact the barrier at the locally planar regions.

7. A space vehicle heat transfer system, comprising,a space vehicle comprising an outer wall separating the crew cabin from outer space;the outer wall configured with at least one barrier having a first side and a second side, the first side disposed on a hot side of the heat transfer system and the second side being disposed on the cold side of the heat transfer system;a first plurality of protrusions on the first side of the barrier, and a second plurality of protrusions on the second side of the barrier;on at least one barrier a first heat pipe having a first plurality of flanges, the first plurality of flanges being joined on the first side of the at least one barrier by fasteners engaging the first plurality of protrusions; anda second heat pipe having a second plurality of flanges, the second plurality of flanges being joined on the second side of the at least one barrier by fasteners engaging the second plurality of protrusions.

8. The space vehicle heat transfer system of claim 7, wherein the first plurality of protrusions extends outwardly from the first side of the at least one barrier and the second plurality of protrusions extends outwardly from the second side of the at least one barrier.

9. The space vehicle heat transfer system of claim 7, wherein first plurality of protrusions and the second plurality of protrusions comprise internally threaded openings and the fasteners are externally threaded.

10. The space vehicle heat transfer system of claim 7, wherein the at least one barrier is penetration-free.

11. The heat transfer system of claim 7, wherein the at least one barrier is penetration-free and locally planar between the first plurality of protrusions and the second plurality of protrusions.

12. The heat transfer system of claim 7, wherein the at least one barrier is penetration-free and with locally planar regions between the first plurality of protrusions and the second plurality of protrusions and the first plurality of flanges and the second plurality of flanges contact the at least one barrier at the locally planar regions.

13. A heat transfer system, comprising, a barrier having a first surface and a second surface, the first surface disposed on a hot side of a heat transfer system and the second surface being disposed on the cold side of the heat transfer system;a first plurality of protrusions on the first side of the barrier, each of the first plurality of protrusions having blind internal threads, and a second plurality of protrusions on the second surface of the barrier, each of the second plurality of protrusions having blind internal threads;a first heat pipe having a first plurality of flanges, the first plurality of flanges being joined on the first surface of the barrier by a plurality of first fasteners engaging the blind internal threads of the first plurality of protrusions; anda second heat pipe having a second plurality of flanges, the second plurality of flanges being joined on the second surface of the barrier by a plurality of second fasteners engaging the blind internal threads of the second plurality of protrusions.

14. The heat transfer system of claim 13, wherein the first plurality of protrusions extends outwardly from the first surface of the barrier and the second plurality of protrusions extends outwardly from the second surface of the barrier.

15. The heat transfer system of claim 13, wherein the plurality of first fasteners comprise externally threaded bolts.

16. The heat transfer system of claim 13, wherein the barrier is penetration-free.

17. The heat transfer system of claim 13, wherein the barrier is penetration-free and locally planar between the first plurality of protrusions and the second plurality of protrusions.

18. The heat transfer system of claim 13, wherein the barrier is penetration-free and with locally planar regions between the first plurality of protrusions and the second plurality of protrusions and the first plurality of flanges and the second plurality of flanges contact the barrier at the locally planar regions.

19. The heat transfer system of claim 13, wherein the heat transfer system is integrated with a space vehicle.

20. The heat transfer system of claim 13, wherein the heat transfer system is integrated with a pressurized crew cabin of a space vehicle.

Images