COOLING SYSTEM FOR LIQUID IMMERSION COOLING OF ELECTRONIC COMPONENTS

Abstract

The invention of interest relates to a cooling system for the liquid immersion cooling of electronic components. The cooling system comprises a container with a vessel wall and, inside, a reservoir for a liquid heat transfer fluid. Positioning devices for electronic components are arranged within the reservoir. The container also has a gas chamber for a gaseous heat transfer fluid. Within the gas chamber of the container is a heat exchanger device with heat exchanger tubes for liquefying the gaseous heat transfer fluid. The heat exchanger tubes have external fins on their outer sides. The heat exchanger tubes pass through the container wall at points of penetration. The heat exchanger tubes are integrally joined to the container wall at these points of penetration.

Description

COOLING SYSTEM FOR LIQUID IMMERSION COOLING OF ELECTRONIC COMPONENTS The invention of interest relates to a cooling system for liquid immersion cooling of electronic components in accordance with the preamble of claim 1. Liquid immersion cooling systems, such as two-stage immersion systems, are an active cooling solution for electronic components that generate a significant amount of heat during operation. When components are immersed in a heat transfer fluid, which typically has a relatively low boiling point, the heat generated by the electronic component vaporizes the surrounding liquid heat transfer fluid, thus dissipating the heat from the component. A condenser then liquefies the heat transfer fluid into vapor, which is returned to the reservoir for cooling. US Patent 10,512,192 B2 describes a two-stage immersion cooling system comprising a cooling tank; a condensation chamber, where the gaseous fluid produced during the cooling process condenses and mixes with the liquid fluid in the cooling tank; and a vapor redirection structure located above the heat-generating electronic components within the cooling medium in the cooling tank. The vaporized fluid is conveyed by the vapor redirection structure to the condensation chamber for liquefaction. US patent 10,477,726 B1 describes a cooling system for computer components. The internal pressure is reduced to 650 hPa inside a pressure-controlled vessel. The vessel contains a dielectric heat transfer fluid that is both liquid and gaseous in phase and has a boiling point below 80°C at atmospheric pressure. The computer components are arranged in the container, at least partially submerged in the liquid phase of the fluid. The dielectric fluid in the gaseous phase CLbcnn / eznz / e / Yi that has been vaporized by the heat generated by the computer components, which is condensed by means of a capacitor to form a liquid-phase dielectric fluid. The object of the invention of interest is to develop a cooling system for the liquid immersion cooling of electronic components with respect to the stability of the container construction. The invention is described by the features of claim 1. The additional dependent claims relate to advantageous embodiments and developments of the invention. The invention relates to a cooling system for the liquid immersion cooling of electronic components. The cooling system comprises a container with a container wall and, inside, a reservoir for a liquid heat transfer fluid, in which positioning devices for electronic components are arranged, the container having a gas space for a gaseous heat transfer fluid. A heat exchanger device with heat exchanger tubes located in the gas space of the vessel for liquefying gaseous heat transfer fluid, wherein the heat exchanger tubes have external fins on their outer sides. The heat exchanger tubes pass through the container wall at the points of contact. The heat exchanger tubes are integrally bonded to the container wall at these points of contact. The gaseous heat transfer fluid in the gas space is in contact with the liquid heat transfer fluid in the reservoir at a phase boundary. The surface of the liquid heat transfer fluid in the reservoir forms the phase boundary with the gaseous heat transfer fluid in the gas space. In other words: heat exchanger tubes can have a smooth outer side or additionally external fins within the points of passage where they pass to the CLbcnn / eznz / e / Yi container wall by means of the container wall. These outer fins are surrounded by the material for an integral bond and are therefore hermetically sealed with respect to the passage of gas or liquid. It is preferred that the outer contour of the tubes characterized by the outer fins be fused with the container wall. For a purely integral bond, it is also advantageously possible to use a combination of a non-positive connection and a positive connection. In addition to the external fins, a heat exchanger tube can also optionally have an internal structure. The internal structure can be designed in the form of an internally circulating helix with a predetermined helix angle. If the outer side of the heat exchanger tubes has external fins circulating in a spiral, the pitch of the circumferential external fins can be equal to, less than, or greater than the pitch of the circulating helix, predetermined by the helix angle. Therefore, the two structures can differ in that the design of the external fins and the internal structure can be designed independently of each other and thus optimized for the integral bonding of the outer sides of a heat exchanger tube to the vessel wall. Furthermore, to optimize heat exchange, both structures are subject to certain limits. Therefore, the ratio between the maximum structural height of the outer fins and the maximum structural height of the inner structure preferably ranges between 1.25 and 5 for the condenser tubes and preferably between 0.5 and 2 for the evaporator tubes. Additionally, the cooling system can advantageously incorporate a control device designed to regulate fluid circulation based, for example, on the temperature of the heat transfer fluid and the pressure conditions within the vessel. Using sensors, the control device monitors and regulates pressure, temperature, conductivity, and all other relevant process parameters. The invention of interest is based on the consideration that a particular stability of the entire construction is permanently achieved by integrally bonding the heat exchanger tubes to the vessel wall. Due to the By direct joining according to the invention at the vessel wall penetration points, known prior art sealing devices, such as butt gaskets, can be dispensed with. Due to the fixed integral joining of the heat exchanger tubes and the vessel wall, it is also possible to reduce the vessel wall thickness compared to conventional technical solutions, since the heat exchanger tubes act as quasi-struts and thus contribute to the dimensional stability of the entire refrigeration system. The solution according to the invention also helps, in particular, with pressure resistance during system operation, both under negative and positive pressure in a hermetically sealed refrigeration system. The arrangement of the heat exchanger tubes within the container can be chosen virtually without restriction. Preferably, it also offers the possibility of positioning the heat exchanger tubes in the gas space near the surface of the liquid heat transfer fluid, particularly at points where especially efficient heat transfer is required. As a result, the heat exchanger tubes perform a variety of functions related to mechanical stability along with efficient heat transfer. A particular advantage is that the solution according to the invention leads to optimization in terms of considerable material savings, along with a significant increase in performance. The electronic components are arranged within the container in a manner suitable for cooling in a liquid heat transfer fluid reservoir. The electronic components are cooled by the vaporization of this liquid fluid. The heat exchanger of the cooling system can be selectively designed to form liquid heat transfer fluid within the gas space of the container, either in the form of advantageously distributed individual tubes or as a tube bundle. Alternatively, multiple tube bundles can be arranged as quasi-modules within the gas space of the container. In each case, these tube bundles are integrally bonded to the container wall at the points where the container wall passes to the outside. For cleaning, the heat exchanger tubes can also be accessed from the outside at the penetration points. With the appropriate connection technology in place. CLbcnn / eznz / e / Yi Outside the container, the system can continue to operate at a reduced cooling capacity even when the individual tubes are cleaned. Therefore, the distribution and introduction of the refrigerant can be carried out entirely outside the container. In a preferred embodiment of the invention, the outer fins may be directly adjacent to or in contact with the vessel wall. This occurs particularly when the heat exchanger tubes still have outer fins within the penetration points where they enter or pass through the vessel wall. Therefore, the outer fins are formed directly adjacent to the integral joint of the tubes with the vessel wall. However, for an integral joint in the case of heat exchanger tubes with finless ends, the tube ends are inserted far enough into the dedicated penetration points so that the adjacent outer fins extend directly to or in contact with the vessel wall.The above has the particular advantage that the heat exchanger tubes have a full set of external fins for efficient heat transfer inside the container. Advantageously, the integral joint can be designed to be gas-tight and pressure-resistant. In addition to the mechanical stability functions associated with efficient heat transfer, a hermetic seal is important to prevent fluid exchange with the environment in any operating mode. In an advantageous embodiment of the invention, within the passage points, the heat exchanger tubes have an inner diameter D2 that is larger than the inner diameter D1 of the heat exchanger tubes outside the passage points. If the heat exchanger tubes still have external fins within the points where they pass into or through the vessel wall, according to the method, a heat exchanger tube enlargement results in an enlarged internal tube diameter D2. Therefore, the external fins are compressed within a point of passage due to the enlargement. However, the integral joint ultimately ensures a stable, airtight seal. CLbcnn / eznz / e / Yi Even in the case of heat exchanger tubes with finless ends, the tube ends are sufficiently flared at the points of passage for integral joining and are further stabilized and sealed by the integral joint. In an advantageous embodiment of the invention, the heat exchanger tubes can be welded, bonded, or brazed to the vessel wall. In addition to the preferred connection types mentioned above, other connection types can also be added that reliably join the heat exchanger tubes to the vessel wall by means of an integral bond. Primarily, the external fins can preferably run along the outer sides of the heat exchanger tubes in a circumferential direction or in an axial direction parallel to the tube axis. In an advantageous embodiment of the invention, the outer sides of the heat exchanger tubes can have spirally arranged external fins. In the case of spirally arranged external fins, only the spiral channel containing the external fins needs to be reliably sealed by an integral joint. In an advantageous embodiment of the invention, the vessel can be configured as a pressurized vessel operating under negative and / or positive pressure. The operating mode of the cooling system can be variably set in relation to the surrounding atmosphere, taking into account the existing mechanical stability associated with efficient heat transfer at both positive and negative pressure. A typical operating mode in practice involves reducing the internal pressure below atmospheric pressure and above 650 torr, where the dielectric fluid typically has a boiling point below approximately 80°C. While a uniform material suitable for heat exchanger tubes is generally preferred, in an advantageous embodiment of the invention at least one first heat exchanger tube may consist of a first material and at least one second heat exchanger tube may consist of a second material that differs from the first material. Steel tubes of particularly high strength may provide a particular advantage with respect to mechanical stability. Copper tubes, however, CLbcnn / eznz / e / Yi result in optimization for efficient heat transfer. Other materials are also considered, such as titanium, aluminum, aluminum alloys, and copper-nickel alloys. Advantageously, the first material can be copper and the second material can be steel. A suitable combination of individual heat exchanger tubes made of these two materials leads to further optimization of the existing mechanical stability associated with efficient heat transfer. Examples of embodiments of the invention are explained in more detail with reference to the schematic drawings, where: Figure 1 schematically shows a front view of a cooling system, Figure 2 schematically shows a front view of a section of the container wall with a passage point, and Figure 3 schematically shows a vertical section through the vessel wall in the plane of the point of passage of a heat exchanger tube. The parts that correspond to each other are provided in all figures with the same reference signs. Figure 1 schematically shows a front view of a cooling system 1 for two-phase liquid immersion cooling of electronic components 2. The cooling system 1 comprises a container 3 and a locking device 9 for exchanging electronic components 2. The electronic components 2 are immersed in the tank 4 comprising liquid dielectric heat transfer fluid located inside the container 3. The heat exchange devices 6 are located in the gas space 5 of the container 3 above the surface 41 of the liquid heat transfer fluid. CLbcnn / eznz / e / Yi The cooling system 1 comprises a heat exchanger device 6 with heat exchanger tubes 61 in the gas space 5 of the vessel 3 for liquefying a gaseous heat transfer fluid. The heat exchanger tubes 61 have external fins on their outer sides, which are not shown in this figure due to the low structural height. The heat exchanger tubes 61 pass through or into the wall of the vessel 31 at points of penetration. The heat exchanger tubes 61 are integrally joined to the wall of the vessel 31 at these points of penetration. The arrangement of the heat exchanger tubes within the vessel is generally flexible.In the container, the heat exchanger tubes 61 are arranged in the gas space 5 but are preferably arranged in bundles or rows at a plurality of points to achieve mechanical stability associated with efficient heat transfer. An automatic loading system, not shown in Fig. 1, can be arranged in container 3 within the cooling system 1. This system allows the electronic components 2 to be transported from the locking device 9 to the operating position 31 in the tank 4, which contains liquid heat transfer fluid for the exchange of the electronic components. The gripping arms of robots or linear transport systems can transport the electronic components 2. These gripping arms automatically retrieve the electronic components 2 to be exchanged from the operating position of the positioning device 8. In reverse, the electronic components 2 to be installed, which are ready for operation, are transferred by the loading system to the operating position in the positioning device 8. Figure 2 schematically shows a front view of a section of the vessel wall 31 with the penetration points 32. The recess in the vessel wall 31 is preferably large enough at penetration point 32 to allow the insertion and integral joining of a heat exchanger tube. Welded and bonded joints can be made at penetration point 32 through the entire wall thickness. Welded connections can be located on the outside and / or inside. With advantageous melt flow, a full-thickness welded joint can be present at penetration point 32, even if the weld is made on only one side from either the outside or inside of the vessel. CLbcnn / eznz / e / Yi Figure 3 schematically shows a vertical section of the vessel wall 31 along the cut line AA of Figure 2 in the plane of the point of penetration of a heat exchanger tube 61. The heat exchanger tube 61 shown has five external fins 62 on its outer sides. The heat exchanger tube 61 penetrates the vessel wall 31 at the point of penetration 32. At this point of penetration, the heat exchanger tube 61 has a continuous set of external fins 62 and an integral joint 7 in the form of a continuous welded seam with the vessel wall 31. Depending on the combination of materials consisting of the vessel wall 31 and the heat exchanger tube 61 at the weld point, advantageous formations of new intermetallic phases in the molten pool may occur. For example, laser welding is a suitable method for producing an integral joint with a locally defined melt flow. CLbcnn / eznz / e / Yi LIST OF REFERENCE SIGNS CLbcnn / eznz / B / Yi 1 Cooling system 2 Electronic component 5 3 Containers 31 Container wall 32 Passage point 4 Tank for liquid heat transfer fluid 41 Surface of liquid heat transfer fluid 10 5 Gas chamber for gaseous heat transfer fluid 6 Heat exchanger device 61 Heat exchanger tube 62 Outer fins 7 Integral link 15 8 Positioning device 9 Locking device AA Cut line

Claims

1. A cooling system (1) for liquid immersion cooling of electronic components (2), comprising: - a container (3) having a container wall (31) and therein a reservoir (4) for liquid heat transfer fluid and in which positioning devices (8) for electronic components (2) are arranged, wherein the container (3) has a gas space (5) for gaseous heat transfer fluid, - a heat exchanger device (6) with heat exchanger tubes (61) in the gas space (5) of the container (3) for liquefying gaseous heat transfer fluid, wherein the heat exchanger tubes (61) have external fins (62) on their outer sides, characterized in that: - the heat exchanger tubes (61) pass into or through the container wall (31) at passage points (32),and - the heat exchanger tubes (61) have an integral joint (7) with the container wall (31) at these points of passage (32)., 2. The cooling system (1) according to claim 1, characterized in that the outer fins (62) at said passage points (32) are directly adjacent to or in contact with the container wall (31).

3. The refrigeration system (1) according to claim 1 or 2, characterized in that the integral joint (7) is designed to be gas-tight and pressure-resistant.

4. The cooling system (1) according to any one of claims 1 to 3, characterized in that inside the passage points (32) the heat exchanger tubes (61) have an inner diameter D2 that is larger than the inner diameter D1 of the heat exchanger tubes (61) outside the passage points (32). CLbcnn / eznz / e / Yi 5. The cooling system (1) according to any one of claims 1 to 4, characterized in that the heat exchanger tubes (61) are welded, glued or soldered to the wall of the vessel (31).

6. The cooling system (1) according to any one of claims 1 to 5, characterized in that the outer sides of the heat exchanger tubes (61) have spirally circulating outer fins (62).

7. The cooling system (1) according to any one of claims 1 to 6, characterized in that the container (3) is configured as a pressurized container that operates under vacuum and / or overpressure.

8. Cooling system (1) according to any one of claims 1 to 7, characterized in that at least one first heat exchanger tube (61) comprises a first material and at least one second heat exchanger tube (61) comprises a second material that differs from the first.

9. The cooling system (1) according to claim 8, characterized in that the first material is copper and the second material is steel.

Images