Cooling system for the liquid immersion cooling of electronic components

Abstract

The invention relates to a cooling system (1) for the liquid immersion cooling of electronic components (2), comprising: a container (3), the interior of which can be filled with a two-phase heat transfer fluid (4), into which electronic components (2) can be immersed in the liquid phase thereof, wherein the container (3) has a gas chamber (5) over the surface (41) of the liquid heat transfer fluid (4) and a lid (6) for closing the container (3) in a fluid-tight manner. The lid (6) or the container (3) has a seal device, comprising a face which faces the gas chamber (5), a face which faces away from the gas chamber (5), and a seal which prevents the passage of a gaseous fluid and which comprises a seal surface. Furthermore, at least the face facing the gas chamber (5) is designed to be continuous as a vapor barrier against the chemical effect of the fluid.

Description

[0001] Description

[0002] Cooling system for liquid immersion cooling of electronic components

[0003] The invention relates to a cooling system for liquid immersion cooling of electronic components according to the preamble of claim 1.

[0004] Depending on the application, conventional electronic components are designed for a specific temperature range during operation, with an upper temperature limit that must not be exceeded. These components must therefore be cooled if necessary to ensure that their internal temperature remains below the specified upper limits. Cooling can be achieved, among other things, by the evaporation of a dielectric heat transfer fluid, such as perfluorocarbons, fluorocarbons, fluoroketones, or fluorocarbon ethers. Depending on its composition, the dielectric heat transfer fluid can have a boiling point at atmospheric pressure in the range of approximately 35°C to approximately 100°C. Within this temperature range, the boiling point of the heat transfer fluid at atmospheric pressure is lower than the permissible upper limits for which conventional electronic components are designed.The electronic components are immersed in the liquid phase of the heat transfer fluid. When the surfaces of the electronic components in contact with the dielectric heat transfer fluid reach the boiling point of the heat transfer fluid, the nearby liquid fluid evaporates, thus absorbing the excess heat from the electronic components. DE 35 22 798 A1 discloses a cooling device for electronic components immersed in a liquid. A liquid container open at the top is closed by a lid. For this purpose, the upper edge of the container is designed as a flange, onto which a simple seal is placed on the flat flange surface and closed with the lid. The container flange is firmly connected to the lid by means of screws.

[0005] Furthermore, the document US 2019 / 0 357 379 A1 describes a two-phase immersion cooling device for electronic components.

[0006] To minimize dielectric losses when using this two-phase system, the cooling tank is provided with a clearance that has an excess height above the condenser device so that only a small amount of vapor from the heat transfer fluid reaches the top of the metal tank.

[0007] In addition, the top of the metal tank is covered by a lid or accessory plate made of metal or glass. The gap between the tank and the lid is sealed with O-rings or other elastomer seals. Although a large portion of the dielectric condenses in the vapor phase at the condenser assembly, in practice, a certain amount of gas reaches the lid and penetrates the gap between the lid and the tank, reaching the seal. Dielectric fluids have the chemical property of attacking and damaging some sealing materials, so the sealing function cannot be reliably guaranteed in the long term.

[0008] The invention is based on the object of developing a cooling system for liquid immersion cooling of electronic components. The invention is defined by the features of claim 1. The further dependent claims relate to advantageous embodiments and developments of the invention.

[0009] The invention includes a cooling system for liquid immersion cooling of electronic components, comprising:

[0010] A container which can be filled internally with a two-phase heat transfer fluid, into the liquid phase of which electronic components can be immersed, wherein the container has a gas space above the surface of the liquid heat transfer fluid and a lid for fluid-tight closure of the container.

[0011] The lid or container has a sealing device with a side facing the gas space and a side facing away from the gas space, and a seal with a sealing surface that prevents the passage of gaseous fluid. Furthermore, at least the side facing the gas space is designed as a vapor barrier resistant to the chemical effects of the fluid.

[0012] The term vapor barrier is used in the context of this invention as a synonym for the term vapor retarder. The effect of the vapor barrier is a

[0013] Barrier that at least inhibits or completely prevents the passage of fluid.

[0014] In two-phase immersion cooling systems, for example, the electronic components are located near the bottom of a metal container. The metal container is filled with a dielectric heat transfer fluid. The liquid phase of the dielectric is in direct thermal contact with the electronic components. During operation, the electronic components generate heat. The heat is dissipated by the components through evaporation of the heat transfer fluid. The dielectric heat transfer fluid has a much lower density in the vapor phase than the heat transfer fluid in the liquid phase and forms a gas space above the surface of the liquid. Condensers, which serve as heat exchange devices, contain water with a temperature at least 15°C below the boiling point of the dielectric in the liquid phase and are located in the gas space of the metal container.The vapor-phase dielectric fluid flows through the capacitor in a generally upward direction. Upon contact with the capacitors, the vapor-phase dielectric fluid transfers heat to the capacitors and returns in the liquid phase. The liquid-phase dielectric, whose density is much higher than that of the vapor-phase dielectric, flows toward the bottom of the metal tank by gravity. The cycle consists of the evaporation of the liquid in contact with the electronic components, the vapor rising above the liquid, the conversion of the vapor to liquid in contact with the capacitors, and the liquid flowing back through the vapor. This cycle allows the heat generated by the electronic components to be transferred to the capacitor.

[0015] The invention is based on the idea that cooling systems for liquid immersion cooling of electronic components comprise a container having a lid for fluid-tight closure of the container. During operation, the cooling system is filled with a two-phase heat transfer fluid, in whose liquid phase electronic components are immersed. The gas phase escaping from the liquid heat transfer fluid collects in the container in a gas space above the surface of the liquid heat transfer fluid and penetrates into the residual gap formed by the lid and container. There, the lid or container has a sealing device with a side facing the gas space and a side facing away from the gas space, as well as a sealing surface preventing the passage of gaseous fluid. Furthermore, at least the side facing the gas space is designed as a vapor barrier resistant to the chemical effects of the fluid.

[0016] The particular advantage is that the side of the sealing device facing the gas space is resistant to chemical influences from the vapor phase of the heat transfer fluid and does not attack or damage the sealing materials used there. In practice, this effectively keeps the gas penetrating the gap between the lid and the container away from chemically sensitive sealing materials, reliably ensuring the sealing function over the long term.

[0017] In a preferred embodiment of the invention, the sealing surface of the seal that prevents the passage of gaseous fluid can be designed to be elastic. Elastic materials, such as thermoplastic elastomers, can be foam-like with a multitude of cavities, for example, as a sealing strip, or can have geometrically hollow structures, such as hollow profiles. Overall, a substantially hermetic seal should be created at the sealing surface, which can withstand both a certain positive and negative pressure within the container.

[0018] Advantageously, the sealing device can be constructed in one piece. Integrated into a single component, the sealing device can function as a vapor barrier on the side facing the gas space, resisting the chemical effects of the fluid. On the other hand, a sealing surface facing away from the gas space can completely prevent the passage of gaseous fluid. Furthermore, a sealing device can be designed that extends continuously over the entire sealing surface.

[0019] In contrast, it is also advantageous that the sealing device can be designed in multiple pieces, with a vapor barrier with one side facing the gas space and a flexible seal with a sealing surface arranged behind the vapor barrier on the side facing away from the gas space and preventing fluid penetration. With this type of sealing device design, a wider range of materials with different and thus optimized properties can be used. The multi-piece sealing device can refer to a pieced, continuous sealing surface as well as to vapor barriers and seals with sealing surfaces arranged one behind the other, starting from the gas space.

[0020] In an advantageous embodiment of the invention, the side of the sealing device facing the gas space can be made of metal. Particularly preferred are elastic metal seals, which effectively seal the gap against gas exchange through their resilient properties. Such elastic metal seals have the ability to spring back in a defined manner when the pressure is removed. Thus, elastic metal seals exert a certain contact pressure on the sealing gap or are designed as a foil applied to a carrier material.

[0021] In an advantageous embodiment of the invention, the side of the sealing device facing the gas chamber can consist of a foil made of aluminum or an aluminum alloy. Aluminum materials, in particular, are suitable as foil materials bonded to a carrier.

[0022] Advantageously, the material forming the sealing surface of the seal can be made of polysiloxane (silicone), fluoroelastomer, polytetrafluoroethylene (PTFE), or nitrile rubber (NBR). Important criteria in the selection of suitable sealing materials are their chemical resistance to the chemical influences of the heat transfer fluid. Further criteria are temperature and aging resistance. In a particularly preferred embodiment, the vapor barrier can be designed to be movable into a groove in the lid or a groove in the container by means of a spring mechanism. The spring action presses the vapor barrier onto the respective counterpart, effectively sealing the gap against gas exchange. In particular, penetration of the vapor barrier into a groove enhances the sealing effect.

[0023] In a further advantageous embodiment of the invention, the sealing device can be designed in a strip-like manner from foam material. Foams usually increase the elasticity of the sealing material, resulting in a uniform sealing function across the entire contact surface on the lid or container.

[0024] Advantageously, the vapor barrier of the sealing device can be designed as a labyrinth seal. A labyrinth seal increases the sealing surface and minimizes the gas passage of the heat transfer fluid.

[0025] Embodiments of the invention are explained in more detail with reference to the schematic drawings.

[0026] Showing:

[0027] Fig. 1 is a schematic view of a cooling system for electronic components according to the invention,

[0028] Fig. 2 is a schematic partial view of the lid and container in the area of ​​a one-piece sealing device,

[0029] Fig. 3 is a schematic partial view of the lid and container in the area of ​​a multi-piece sealing device, and

[0030] Fig. 4 shows a schematic partial view of the lid and container in the area of ​​another multi-piece sealing device. Corresponding parts are provided with the same reference numerals in all figures.

[0031] Fig. 1 shows a schematic view of a cooling system 1 according to the invention for electronic components 2. The cooling system 1 comprises a container 3, which is filled internally with heat transfer fluid 4, in whose liquid phase electronic components 2 are immersed. Their container 3 has a gas space 5 above the surface 41 of the liquid heat transfer fluid 4. The container 3 is sealed fluid-tight by a lid 6. At the common contact surface, the lid 6 or the container 3 has a sealing device 7, shown enlarged in image section A in Figure 2, with a sealing surface preventing the passage of gaseous fluid.

[0032] The evaporated dielectric heat transfer fluid forms a gas space 5 above the surface 41 containing a gaseous phase, in which a heat exchanger device 8 with tube bundles 81 as condensers is arranged. Water flows through the tube bundles 81 at a significantly lower temperature, below the boiling point of the dielectric. Upon contact with the condensers of the tube bundles 81, the gaseous fluid releases condensation heat.

[0033] Fig. 2 shows a schematic partial view A of the lid 6 and container 3 from Fig. 1 in the area of ​​a one-piece sealing device 7.

[0034] The sealing device 7 is designed as a strip and is embedded in a groove 61 in the cover 6. The sealing surface 74 preventing the passage of gaseous fluid is located on the container side.

[0035] The one-piece strip as sealing device 7 is functionally resistant to the chemical effects of the fluid on the side 71 facing the gas space 5 as a vapor barrier 70. The sealing surface 74 facing away from the gas space 5 is protected by the vapor barrier 70 and prevents the passage of the remaining gaseous fluid. On the side 71 facing the gas space 5, a metal strip or a metal foil is arranged as a vapor barrier 70. A particularly suitable metal is aluminum or an aluminum alloy, which can preferably be used as a flexible foil material. In this way, the sealing device 7 can run in one piece without interruption over the entire sealing surface 74 between the container 3 and the lid 6. In special cases, several sections joined together to form a whole can also be suitable for the sealing device 7.

[0036] Elastic metal foils as vapor barrier 70 effectively seal the gap against gas penetration, so that only a very small amount of the gaseous fluid reaches the sealing surface 74 of the seal 73 located behind it. The metal foils are attached to a carrier material, in the case of the one-piece design directly to the seal 73.

[0037] The seal 73 of the sealing device 7 can preferably also be made of foam material in conjunction with an elastically flexible metal foil as a vapor barrier 70. Foams usually increase the elasticity of the sealing material, resulting in a uniform sealing function across the entire contact surface.

[0038] Fig. 3 shows a schematic partial view A of the lid 6 and container 3 from Fig. 1 in the area of ​​a multi-piece sealing device 7.

[0039] The sealing device 7 is constructed in several pieces, comprising a vapor barrier 70 with a side 71 facing the gas chamber and a flexible seal 73 with a sealing surface 74 arranged behind the vapor barrier on the side 72 facing away from the gas chamber. Such a multi-piece sealing device 7 comprises, starting from the gas chamber 5, successively arranged and spaced-apart vapor barriers 70 and seals 73 with sealing surfaces 74. The vapor barrier 70 is embedded in a groove 61 in the lid 6. Likewise, the seal 73 is fixed, projecting upwards, in another groove for support. The sealing surface 74, which prevents the passage of gaseous fluid, is located on the container side.

[0040] In this embodiment, the vapor barrier 70 is designed to be movable into the groove 61 in the lid 6 by means of a spring mechanism 75. The spring action guides the vapor barrier 70 in the groove 61 and presses it against the respective counterpart, the container 3. This effectively seals the gap against gas exchange toward the subsequent seal 73.

[0041] In this case, the vapor barrier 70 of the sealing device 7 projects over the top to the side wall of the container 3, thus creating particularly large passageways for the gaseous fluid. Such labyrinth seals thus increase the sealing surface and minimize the passage of the heat transfer fluid through to the seal 73.

[0042] Fig. 4 shows a schematic partial view A of the lid 6 and container 3 from Fig. 1 in the area of ​​a further embodiment of a multi-piece sealing device 7.

[0043] The sealing device 7 is designed with a vapor barrier 70 with a side 71 facing the gas space and a flexible seal 73 with a sealing surface 74 arranged behind the vapor barrier on the side 72 facing away from the gas space. This multi-piece sealing device 7 again comprises, starting from the gas space 5, successively arranged and spaced-apart vapor barriers 70 and seals 73 with sealing surfaces 74. The vapor barrier 70 is recessed into a groove 61 in the lid 6. Likewise, the seal 73 is secured in a further groove, projecting upwards. The seal 73, which prevents the passage of gaseous fluid and has the sealing surface 74, is located directly adjacent to the vapor barrier 70 on the container side. This further preferred embodiment thus combines the technical configurations shown and explained in Fig. 2 and Fig. 3 in a simple solution for a multi-piece sealing device 7.

[0044] List of reference symbols

[0045] 1 cooling system

[0046] 2 electronic components

[0047] 3 containers

[0048] 31 Groove in the container

[0049] 4 Heat transfer fluid

[0050] 41 Surface of the liquid heat transfer fluid

[0051] 5 Gas room

[0052] 6 lids

[0053] 61 Groove in the lid

[0054] 7 Sealing device

[0055] 70 vapor barrier

[0056] 71 Gas chamber facing side of the sealing device

[0057] 72 Gas chamber facing away from the sealing device

[0058] 73 Seal

[0059] 74 Sealing surface

[0060] 75 spring mechanism

[0061] 8 Heat exchanger device

[0062] 81 tube bundles

[0063] A Image section of the sealing area

Claims

Patent claims 1 . Cooling system (1) for liquid immersion cooling of electronic components (2), comprising - a container (3) which can be filled inside with a two-phase heat transfer fluid (4), in the liquid phase of which electronic components (2) can be immersed, wherein the container (3) has a gas space (5) above the surface (41) of the liquid heat transfer fluid (4), - a lid (6) for fluid-tight closure of the container (3), characterized in - that the lid (6) or the container (3) has a sealing device (7) with a side (71) facing the gas space (5) and a side (72) facing away from the gas space (5) and a seal (73) with a sealing surface (74) preventing the passage of gaseous fluid, - that at least the side (71) facing the gas space (5) is designed as a vapor barrier (70) resistant to the chemical action of the fluid.

2. Cooling system (1) according to claim 1, characterized in that the sealing surface (74) of the seal (73) preventing the passage of gaseous fluid is designed to be elastic.

3. Cooling system (1) according to claim 1 or 2, characterized in that the sealing device (7) is designed in one piece.

4. Cooling system (1) according to claim 1 or 2, characterized in that the sealing device (7) is designed in several pieces with a vapor barrier (70) with a side (71) facing the gas space (5) and a flexible seal (73) with a sealing surface (74) arranged behind the vapor barrier (70) on the side (72) facing away from the gas space (5) and preventing the passage of fluid.

5. Cooling system (1) according to one of claims 1 to 4, characterized in that the side (71) of the sealing device (7) facing the gas space (5) is made of metal.

6. Cooling system (1) according to claim 5, characterized in that the side (71) of the sealing device (7) facing the gas space (5) consists of a foil made of aluminum or an aluminum alloy.

7. Cooling system (1) according to one of claims 1 to 6, characterized in that the material of the seal (73) forming the sealing surface (74) consists of polysiloxane, fluoroelastomer, polytetrafluoroethylene and / or nitrile rubber.

8. Cooling system (1) according to one of claims 1 to 7, characterized in that the vapor barrier (70) is designed to be displaceable by means of a spring mechanism (75) into a groove (61) in the lid (6) or a groove (31) in the container (3).

9. Cooling system (1) according to one of claims 1 to 8, characterized in that the sealing device (7) is designed in the form of a strip made of foam material.

10. Cooling system (1) according to one of claims 1 to 9, characterized in that the vapor barrier (70) of the sealing device (7) is designed as a labyrinth seal.

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