Cooling system for immersion cooling of electronic components

Abstract

The present invention relates to a cooling system (1) for immersion cooling of an electronic component (2), comprising a container (3) capable of being filled with a two-phase heat transfer fluid (4) capable of immersing the electronic component (2) in its liquid phase, the container (3) having a gas chamber (5) above a surface (41) of the liquid heat transfer fluid (4), a heat exchanger (6) in the gas chamber (5) of the container (3) for forming the liquid heat transfer fluid (4) and a condenser unit (8) arranged outside the container (3). In this cooling system (1), a condenser unit (8) is connected to the gas chamber (5) in the vessel (3) by fluid lines (7) as a supply line (71) and a return line (72) for mass transfer of the gaseous medium to the condenser unit (8) and mass transfer of the condensed heat transfer fluid to the vessel (3), the condenser unit (8) has an outlet (81) through which the residual gas phase can be discharged, and the fluid lines (7) as the supply line (71) and the return line (72) of the condenser unit (8) are single tubes with an appropriate cross-sectional area or double tubes connected to the vessel (3).

Description

[Technical Field]

[0001] The present invention relates to a cooling system for immersion cooling of electronic components according to the preamble of claim 1. [Background technology]

[0002] A cooling system for immersion cooling, such as a two-phase immersion cooling system, is an active cooling solution for electronic components that generate a lot of heat during operation. By immersing the component in a two-phase heat transfer fluid with a primarily low boiling point, the heat generated by the electronic component vaporizes the surrounding liquid heat transfer fluid, thereby dissipating the heat from the electronic component. The gaseous heat transfer fluid is liquefied by a condenser unit and then returned to the reservoir for cooling.

[0003] Patent document 1 discloses a two-phase immersion cooling system with a cooling bath. A condensation chamber, which condenses the gaseous fluid produced during the cooling process, is connected to the liquid fluid in the cooling bath. Here, heat-generating electronic components are located in the cooling medium in the cooling bath, above which a vapor bypass structure is arranged. The vaporized fluid is sent by means of the vapor bypass structure to the condensation chamber for liquefaction. The condensation chamber is completely located inside the cooling bath.

[0004] In this regard, Patent Document 2 discloses a cooling system for computer components. A thermally conductive, dielectric heat transfer fluid having a boiling point below 80°C at atmospheric pressure exists in both liquid and gas phases within a pressure-controlled enclosure. A computer component is located within the enclosure, at least partially immersed in the liquid phase of the heat transfer fluid. A condenser condenses the gaseous dielectric fluid, vaporized by heat generated by the computer component, into a liquid dielectric fluid. The pressure within the pressure-controlled enclosure is reduced to 650 hPa. By controlling the pressure within the enclosure in which the system is operating, the user can influence the temperature at which the dielectric liquid vaporizes. This allows for improved cooling performance. Operating a computer system within a pressure-controlled enclosure at an operating pressure different from ambient pressure often requires adapting the overall structural design of the system.

[0005] Patent Document 3 discloses a cooling system having a container filled with a two-phase heat transfer fluid as a refrigerant, in which electronic components can be immersed in the liquid phase. The container has a gas chamber above the surface of the liquid heat transfer fluid. A separate external condenser unit is arranged on the container together with the electronic components, configured to condense the vapor phase of the heat transfer fluid and return it to the container as a liquid refrigerant. The system comprises a return line and a supply line connected to both the condenser unit and the container, forming a heat exchange loop. Furthermore, the system comprises a collection container installed on the supply line, configured to collect the condensed liquid heat transfer fluid before the refrigerant is supplied to the container. Furthermore, the heat accumulator also provides a reserve cooling capacity for the cooling system.

[0006] Patent Document 4 discloses a cooling system for immersion cooling of electronic components. The system includes a pressure tank configured to hold a heat transfer fluid in liquid form, in which the electronic device is immersed. Furthermore, a vapor chamber is located above the surface of the liquid heat transfer fluid. A condenser is arranged outside the pressure tank and has an inlet connected to the vapor chamber by a riser tube, the inlet configured to receive the vapor of the heat transfer fluid. Furthermore, the condenser has a tightly sealable vapor outlet for residual gas and a condensate outlet with a condensate return line to the tank. The condensate return line is configured so that the condensed heat transfer fluid can return from the condensate outlet to the tank. An additional condenser tube can be provided inside the tank for liquefying the gaseous heat transfer fluid. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 10,512,192 [Patent Document 2] U.S. Patent No. 10,477,726 [Patent Document 3] U.S. Patent Publication No. 2021 / 0153392 [Patent Document 4] European Patent No. 3453235 Summary of the Invention [Problem to be solved by the invention]

[0008] The invention is based on the task of further developing a cooling system for immersion cooling of electronic components with respect to a heat exchanger for a heat transfer fluid. [Means for solving the problem]

[0009] The invention is described by the features of claim 1. The other related claims are advantageous embodiments and developments of the invention.

[0010] The present invention includes a cooling system for immersion cooling of electronic components. The cooling system includes a container, the container being capable of being filled with a two-phase heat transfer fluid, the electronic components being immersed in the liquid phase. The container has a gas chamber above the surface of the liquid heat transfer fluid. The cooling system further includes a heat exchanger in the gas chamber of the container for forming the liquid heat transfer fluid. The cooling system further includes a condenser unit disposed outside the container, the condenser unit being connected by fluid lines as a supply line and a return line to the gas chamber of the container for mass transfer of a gaseous medium to the condenser unit and of a condensed heat transfer fluid to the container, the condenser unit having an outlet through which the residual gas phase can be discharged. According to the present invention, the fluid lines as the supply line and the return line of the condenser unit are a single tube with an appropriate cross-sectional area or a double tube connected to the container.

[0011] The vessel can be designed to be pressure resistant. The vessel can advantageously be designed as a pressure vessel capable of operating under vacuum and / or pressure. By controlling the pressure within the vessel at which the cooling system operates, increased cooling capacity can be achieved.

[0012] The heat exchanger in the gas chamber preferably comprises at least one tube bundle of heat exchange tubes arranged parallel to one another. The tube bundle may have a number of heat exchange tubes arranged parallel to one another with two end tube sheets. The tube bundle or heat exchange tubes in the vessel may be arranged symmetrically with respect to the vessel wall, as well as non-symmetrically or along an incline.

[0013] The supply and return lines of the condenser unit may be a single tube of suitable cross-sectional area connected to the vessel. Both the mass transfer of the gaseous medium and the mass transfer of the condensed heat transfer fluid take place through this single tube. The cross-sectional area of ​​the tube is appropriately dimensioned so that the gaseous and liquid media flowing in opposite directions within the same tube do not interfere with each other's flow characteristics. Practical experience has shown that the condensed heat transfer fluid flows along the inner tube wall to the vessel due to its wetting properties, while the gaseous heat transfer fluid flows in the center of the tube in the opposite direction to the condenser.

[0014] Alternatively, the supply and return lines of the condenser unit can be double-tubed, connected to a container. Mass transfer of the gaseous medium occurs through the internal supply line, while mass transfer of the condensed heat transfer fluid occurs through the return line surrounding the internal supply line. The appropriate cross-sectional areas of the supply and return lines are dimensioned to ensure that the gaseous and liquid media flowing through the respective lines have minimal resistance to their flow characteristics. Practical experience has shown that, due to the smaller volume of the condensed heat transfer fluid, the cross-sectional area of ​​the casing tube of the return line can be smaller than that of the internal supply line for the gaseous heat transfer fluid.

[0015] The heat exchanger tubes are preferably ribbed tubes manufactured from smooth tubes through forming processes. They are particularly suitable as components in highly efficient, compact, and extremely stable heat exchangers with high heat transfer coefficients. The tube surface is optimized for the specific heat transfer requirements of the application. A wide range of materials, including copper, copper alloys, steel, titanium, and titanium alloys, ensures that the right material is available for your requirements, especially in terms of durability and formability.

[0016] The two-phase heat transfer fluid, also known as the refrigerant, is the external fluid in the vessel, the liquid portion of which the electronic components are immersed. The internal fluid in the heat exchanger tubes is typically a single-phase heat transfer medium, such as process water, glycol, or thermal oil. However, two-phase media in combination with a refrigeration cycle can also be used in the present invention.

[0017] Within the vessel, the electrical components are placed in a bath of liquid heat transfer fluid in a manner suitable for cooling, and the liquid fluid evaporates to cool the electrical components, whereby a portion of the non-condensable gas can be effectively removed from the system before or during start-up.

[0018] In embodiments according to the present invention, computer components and immersion cooling devices, as well as associated power supplies, network connections, wiring connections, etc., can be placed within a container that, during operation, has an internal pressure that is different from the ambient pressure.

[0019] In this regard, it is also advantageous to combine the wiring for the electrical connections, water connections, negative pressure connections and network connections into one bundle to minimize feed-through into the container and reduce the risk of leakage, especially when the system is under negative or positive pressure during operation.

[0020] In advantageous embodiments, the vessel is maintained at a pressure up to 200 hPa below ambient atmospheric pressure during operation, which contributes to lowering the boiling point of the two-phase heat transfer fluid and thereby reducing the operating temperature of computer chips and other components. In some particular embodiments, the pressure-controlled vessel can further have a pressure up to 500 hPa below ambient pressure.

[0021] An embodiment of a cooling system according to the present invention includes a vessel designed to use a two-phase liquid immersion cooling system. The vessel includes a reservoir of dielectric cooling fluid, a heat exchanger, and an external condenser unit for condensing the dielectric fluid from its gas phase to a liquid. The external condenser unit is designed to condense as much of the remaining gaseous heat transfer fluid, which contains a proportion of air and water vapor, into a liquid heat transfer fluid. Ideally, the remaining heat transfer fluid is nearly completely condensed from its gas phase, leaving essentially only air and water vapor as the residual gas phase. The objective in separating the liquid heat transfer fluid is to maintain the water vapor in the gas phase by utilizing the system's adequate cooling capacity. This residual gas mixture is discharged from the cooling system through an outlet of the condenser unit.

[0022] Additionally, there may be provisions for holding computer components and distributing power from a power system to devices and components located within the enclosure. It will be appreciated that numerous specialized connections are used to operate a computer system within an enclosure maintained at a negative pressure, for example. In some embodiments of systems according to the present invention, a series of fiber optic interfaces may be used to enable connectivity within the enclosure and distribute the fibers to the various holding devices for the electronic components. Some embodiments of the enclosure may include monitoring sensors for safe operation. These sensors may include temperature sensors, fluid level sensors, pressure sensors, position sensors, electrical sensors, and / or cameras to ensure and automate the operation of the system.

[0023] These systems may, for example, include a pressure sensor inside the pressure-controlled vessel to monitor the pressure and ensure there are no significant leaks, as well as a gas sensor located outside the pressure-controlled vessel to detect the presence of dielectric vapors that may escape from the pressure-controlled vessel.

[0024] In addition, the cooling system may advantageously also comprise a control device, which is arranged to control the operation of the fluid circulation, e.g. as a function of the temperature of the two-phase heat transfer fluid, and to control the pressure ratio within the vessel.

[0025] Advantageously, a positioning system can be provided that can transport the electronic component from the locking device to an operating position for replacement. The positioning system can consist of a robotic arm or a linear drive unit. If the device is appropriately designed, a fully automatic positioning system can be used to replace the component. Alternatively, to replace the electronic component of the locking device in the operating position, a glove can be placed over the opening of a suitable container, which allows manual access to the interior of the container for installation.

[0026] In an advantageous embodiment of the invention, the fluid line may have a structured inner surface. In the case of a single tube, the inner surface may have ribbed, grooved, porous structural features or protrusions that direct the condensed heat transfer fluid along the inner surface of the tube to the inlet of the vessel. In the case of a double tube plumbing to the vessel, the inner surface of the inner return line is similarly designed with ribbed, grooved, porous, or protrusions to direct the condensed heat transfer fluid in a specific direction. In contrast, the inner surface of the outer tube surrounding the return line for conducting the gaseous heat transfer fluid can also be designed smoothly.

[0027] In a particularly advantageous embodiment of the cooling system of the present invention, the structured inner surface of the fluid line may be a spirally wound rib for directing the condensed heat transfer fluid into the container, with an appropriate pitch of the ribs causing the fluid to be directed spirally by gravity on the inner wall of the tube.

[0028] In an advantageous design, the fluid line may be a tube laid at an angle to gravity or a double tube, so that the condensed heat transfer fluid returns to the vessel by gravity on at least a portion of the inner wall. In a single tube, the condensed heat transfer fluid flows along the lower inner wall, while the gaseous heat transfer fluid flows back up the upper inner wall.

[0029] Advantageously, the angle of inclination of the fluid lines relative to gravity can be at least 2°, preferably at least 5°, and particularly preferably at least 15°. Even such a slight angle of inclination can prevent the condensed heat transfer fluid from falling freely and uncontrollably inside the tubes as it is returned to the container. In particular, in the case of a single tube, uncontrolled flow or turbulence can be prevented, which prevents the gaseous heat transfer fluid from flowing back.

[0030] In a preferred embodiment of the invention, the supply line, return line and / or outlet can be opened or closed by individual valves or in combination with each other. For proper process control, the individual valves are opened as needed to allow the passage of a gaseous medium or a liquid heat transfer fluid. The supply or removal can be carried out in cyclic or continuous mode. In particular, the outlet valve circuit is designed to ensure little or no leakage of the heat transfer fluid from the cooling system.

[0031] In an advantageous embodiment of the invention, a collection vessel can be arranged downstream of the outlet, through which the residual gas phase can be discharged. This vessel prevents ambient air from entering the cooling system. The vessel can be an inflatable elastic balloon or a bellows with variable volume.

[0032] Advantageously, a drying unit can be arranged between the outlet and the collection vessel to separate the water vapor from the gas phase. For example, when the load changes, the pressure situation throughout the cooling system also changes. If necessary, fresh air can be introduced into the cooling system from the collection vessel for pressure balancing, or residual gas can be introduced from the drying unit. The water vapor is then chemically bonded to the drying unit. Silica gel is suitable for such a drying unit.

[0033] In an advantageous embodiment of the invention, a vacuum pump can be arranged downstream of the outlet, through which the residual gas phase can be evacuated, whereby the residual gas phase of water vapor and air at the outlet can also be at a lower pressure than the ambient, since the vacuum pump always ensures that the flow direction of the residual gas phase is outward.

[0034] Advantageously, the heat exchanger and condenser unit can share a common supply unit for the single-phase heat transfer medium for cooling, so that both units are at a constant temperature level, suitable for the heat exchanger fluid separation process.

[0035] Advantageously, the amount of single-phase heat transfer medium for cooling the heat exchangers and condenser units of the common supply unit can be apportioned by actively controlling the single-phase heat transfer medium flow rate.

[0036] Multi-way valves, especially three-way valves, are particularly suitable for actively controlling the flow rate. Alternatively or in combination, a throttle or frequency-controlled pump can be integrated into the supply unit to regulate the flow rate. This allows the cooling capacity of the heat exchanger and condenser unit to be appropriately adjusted and controlled by a single supply unit.

[0037] In an advantageous embodiment of the invention, a cooling device can be arranged at least partially on the fluid line. This can be a cooling tube or a cooling cuff wound in a spiral around the fluid line. This effectively prevents the liquid fluid from being reheated above its boiling point by the warm gaseous fluid flowing in the opposite direction. In particular, this method further reduces the temperature of the liquid fluid flowing along the inner wall of the fluid line.

[0038] An example of an embodiment of the present invention will be described in more detail based on a schematic diagram. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a schematic diagram of a cooling system having a condenser unit and tubes as fluid lines. [Figure 2] FIG. 1 is a further schematic diagram of a cooling system having a condenser unit and double tubes as fluid lines. DETAILED DESCRIPTION OF THE INVENTION

[0040] In all the figures, corresponding parts are given the same reference numerals.

[0041] 1 shows a schematic diagram of a cooling system 1 including a condenser unit 8 and tubes 7 as fluid lines for immersion cooling of an electronic component 2. The cooling system 1 includes a vessel 3 filled with a two-phase heat transfer fluid during operation. The two-phase heat transfer fluid is an external fluid in the vessel 3, which includes a liquid heat transfer fluid portion 4 in which the electronic component 2 is immersed, and a gas chamber 5 having a gas heat transfer fluid portion. A heat exchanger 6 is disposed within the gas chamber 5 of the vessel 3 to form the liquid heat transfer fluid 4.

[0042] In this advantageous embodiment, the heat exchanger 6 in the gas chamber 5 consists of tube bundles 61, each tube bundle 61 having a number of heat exchange tubes arranged parallel to one another.

[0043] 1, the vessel 3 in the illustrated embodiment has a slightly tapered area for the liquid heat transfer fluid 4, as the vessel wall protrudes inwards and finally opens into the gas chamber 5. The shape of the vessel 3 is supported by a metal profile frame 31. The vessel 3 is therefore already surrounded by a stable outer frame.

[0044] The condenser unit 8 is arranged outside the vessel above the vessel 3. The condenser unit 8 is connected to the gas chamber 5 of the vessel 3 by fluid lines 7 serving as supply and return lines 71 and 72 for the mass transfer of gaseous medium and condensed heat transfer fluid between the vessel 3 and the condenser unit 8. In the variant shown in Figure 1, the fluid lines 7 are designed as a single tube with an appropriate pipe cross-section as the supply and return lines 71 and 72 of the condenser unit 8.

[0045] To control mass transfer, a valve 700 is selectively installed in fluid line 7. A gaseous mixture of heat transfer fluid, air, and water vapor is periodically or continuously extracted from vessel 3 through valve 700. The liquid heat transfer fluid is returned to vessel 3 through the same valve 700.

[0046] 1, a cooling device 73 is disposed on the fluid line 7. In the illustrated embodiment, the cooling device 73 is a cooling cuff through which a refrigerant flows during operation, thereby further cooling the exterior of the fluid line 7 and, therefore, the liquid fluid flowing therethrough. In particular, the liquid fluid in contact with the interior wall of the fluid line 7 is thus effectively maintained at a temperature well below its boiling point.

[0047] The residual gas phase can be fed to a collection vessel 9 through a supply line 91 equipped with a valve 910, which can be designed as a bellows whose volume can expand when pressure is applied to create a vacuum. When the valve 910 to the collection vessel 9 is closed during operation, the residual gas can be discharged through a discharge line 92 of the collection vessel 9 at an open valve 920.

[0048] For further separation of water vapor, a drying unit 11 is arranged between the outlet 81 and the collection vessel 9 to separate the water vapor from the gas phase. Depending on the pressure conditions, the remaining gas phase can be discharged directly to the environment.

[0049] Alternatively, the residual gas phase can be removed using a vacuum pump 10. The outlet 81 is connected to the vacuum pump 10 via a supply line 101, and the vacuum pump 10 regulates the residual gas flow rate to the outside via a discharge line 102 of the vacuum pump 10 via a valve control 1010.

[0050] FIG. 2 shows a schematic diagram of a cooling system 1 including a condenser unit 8 and a double tube 7 as a fluid line for immersion cooling of an electronic component 2. As an alternative to the embodiment shown in FIG. 1, the double tube serves as a supply line 71 for a gaseous medium to the condenser unit 8 and as a return line 72 for the condensed heat transfer fluid of the condenser unit 8, which is connected to the container 3. Mass transfer of the gaseous medium occurs via the inner-laid supply line 71. Mass transfer of the condensed heat transfer fluid occurs via the return line 72 surrounding the inner-laid supply line 71. Here, the inner-laid supply line 71 can be slightly longer than the surrounding return line 72 when entering the condenser unit 8. In this way, the condensed heat transfer fluid enters only the return line 72 during system operation and does not enter the supply line 71, which unintentionally extends into the condenser unit 8.

[0051] The supply line 71 can be opened or closed individually or in combination by a valve 710, and the return line 72 by a further valve 720. For proper process control, the individual valves are opened as required to allow passage of a gaseous medium or a liquid heat transfer fluid. [Explanation of symbols]

[0052] 1. Cooling system 2. Electronic Components 3 containers 31 Metal Profile Frame 4. Liquid heat transfer fluids 41 Liquid fluid surface in a container 5. Gaseous heat transfer fluid, gas chamber 6 Heat exchanger 61 tube bundle 7 Fluid Lines 700 Fluid Line Valves 71 Supply Line 710 Supply line valve 72 Return line 720 Return line valve 73 Cooling device 8 Condenser unit 81 Exit 810 Outlet valve 9 Collection container, bellows 91 Supply line collection container 910 Supply line collection vessel valve 92 Discharge line collection container 920 Discharge line collection vessel valve 10. Vacuum pump 101 Supply line vacuum pump 1010 Supply line vacuum pump valve 102 Discharge line vacuum pump 11 Drying unit

Claims

1. A cooling system (1) for immersion cooling of an electronic component (2), comprising: - a container (3) capable of being filled with a two-phase heat transfer fluid (4) capable of immersing the electronic component (2) in its liquid phase, the container (3) having a gas chamber (5) above the surface (41) of the liquid heat transfer fluid (4), a heat exchanger (6) for forming said liquid heat transfer fluid (4) in the gas chamber (5) of said container (3); a condenser unit (8) arranged outside the vessel (3), said condenser unit (8) being connected to the gas chamber (5) of the vessel (3) by fluid lines (7) as a supply line (71) and a return line (72) for mass transfer of a medium in gaseous state to the condenser unit (8) and of a condensed heat transfer fluid to the vessel (3), said condenser unit (8) having an outlet (81) through which the residual gas phase can be discharged; - the fluid lines (7) as the supply line (71) and the return line (72) of the condenser unit (8) are single tubes with an appropriate cross-sectional area or double tubes connected to the container (3).

2. 2. The cooling system (1) according to claim 1, characterized in that the fluid lines (7, 71, 72) have a structured inner surface.

3. 3. The cooling system (1) according to claim 2, characterized in that the structured inner surface of the fluid line (7, 71, 72) is a spirally wound rib.

4. 4. Cooling system (1) according to any one of claims 1 to 3, characterized in that the fluid lines (7, 71, 72) are tubes or double tubes running at an inclined angle against gravity.

5. 5. The cooling system (1) according to claim 4, characterized in that the angle of inclination of the fluid lines (7, 71, 72) with respect to gravity is at least 2°.

6. 6. A cooling system (1) according to any one of claims 1 to 5, characterized in that the supply line (71), the return line (72) and / or the outlet (81) can be opened or closed individually or in combination by valves (700, 710, 720, 810).

7. 7. A cooling system (1) according to any one of claims 1 to 6, characterized in that a collecting vessel (9) is arranged downstream of the outlet (81) through which the residual gas phase can be discharged.

8. 8. The cooling system (1) according to claim 7, characterized in that a drying unit (11) is arranged between the outlet (81) and the collection vessel (9) for the separation of water vapor from the gas phase.

9. 7. A cooling system (1) according to any one of claims 1 to 6, characterized in that downstream of said outlet (81) a vacuum pump (10) is arranged, through which the residual gas phase can be evacuated.

10. 10. Cooling system (1) according to any of the preceding claims, characterized in that the heat exchanger (6) and the condenser unit (8) have a common supply unit of single-phase heat transfer medium for cooling.

11. 11. The cooling system (1) of claim 10, wherein the amount of the single-phase heat transfer medium for cooling the heat exchanger (6) and the condenser unit (8) of the common supply unit can be allocated by actively controlling the single-phase heat transfer medium flow rate.

12. 12. Cooling system (1) according to any of the preceding claims, characterized in that a cooling device (73) is arranged at least partially on the fluid line (7).

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