Cooling system for liquid immersion cooling of electronic components

Abstract

The invention relates to a cooling system for liquid immersion cooling of an electronic component (2), comprising: a container (3), the interior of which can be filled with a two-phase heat transfer fluid (4) in which the electronic component (2) can be immersed, the container (3) having a gas space (5) above a surface (41) of the liquid heat transfer fluid (4),-a heat exchanger device (6), the invention relates to a heat exchanger (1) comprising a container (3) having a gas space (5) in which a gaseous medium mass is to be transferred, located in the gas space (5) of the container (3) for the purpose of forming a liquid heat transfer fluid (4), a condenser unit (8) arranged outside the container (3), which condenser unit (8) is connected to the gas space (5) of the container (3) by means of a fluid line (7) as a feed line (71) and a return line (72) in order to transfer the gaseous medium mass to the condenser unit (8), the condenser unit (8) has an outlet (81) via which the residual gas phase can be discharged, and-the fluid line (7) as a feed line (71) and a return line (72) of the condenser unit (8) is a single-tube line or a double-tube line with a suitable line cross-section connected to the container (3).

Description

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

[0002] In the form of a two-phase immersion cooling system, for example, a cooling system for liquid immersion cooling is an active cooling solution for electronic components that generate a large amount of heat during operation. Since the components are immersed in a two-phase heat transfer fluid, which typically has a low boiling point, the heat generated by the electronic components can evaporate the surrounding liquid heat transfer fluid, thereby removing heat from the electronic components. A condenser device liquefies the gaseous heat transfer fluid, which is then returned to the reservoir for cooling.

[0003] US 10 512 192 B2 discloses a two-phase immersion cooling system with a cooling tank. A condenser chamber that condenses the gaseous fluid formed during the cooling process is connected to the liquid fluid in the cooling tank. In this case, a vapor redirection structure is arranged above the heat-generating electronic components in the cooling medium located in the cooling tank. By means of the vapor redirection structure, the evaporated fluid is guided into the condensation chamber for liquefaction. The condensation chamber is completely located in the cooling tank.

[0004] In this context, a cooling system for computer components is known from US 10 477 726 B1. In a pressure-controlled container, a heat-conducting dielectric heat transfer fluid is present in a liquid phase and a gas phase, which fluid has a boiling point below 80° C. at atmospheric pressure. Computer components are arranged in the container, which are at least partially immersed in the liquid phase of the heat transfer fluid. By means of a condenser, the dielectric electric phase fluid evaporated by the heat generated by the computer components is condensed to form a dielectric liquid phase fluid. Inside the pressure-controlled container, the internal pressure is reduced to as low as 650 hPa. By controlling the pressure in the container in which the system operates, the user can influence the temperature at which the dielectric liquid evaporates. In this way, an increased cooling capacity can be obtained. The operation of a computer system in a pressure-controlled container at an operating pressure different from the ambient pressure generally requires a design adaptation of the system as a whole.

[0005] US 2021 / 0 153 392 A1 discloses a cooling system including a container, which can be filled with a two-phase heat transfer fluid as a coolant, and electronic components can be immersed in the liquid phase of the container. The container has a gas space above the surface of the liquid heat transfer fluid. Arranged above the container is a separate external condenser device, which is configured so that it condenses the vapor phase of the heat transfer fluid and feeds it back to the container containing these electronic components as a liquid coolant. For this purpose, the system includes a return line and a feed line, which are connected to both the condenser device and the container to form a heat exchange loop. The system further includes a collection container, which is arranged on the supply line and is configured in such a way that the collection container collects the condensed liquid heat transfer fluid before the coolant is fed to the container. The accumulator also provides reserve cooling capacity for the cooling system.

[0006] EP 3 453 235 B1 discloses a cooling system for immersion cooling of electronic components, the cooling system comprising a pressure-sealed tank, the tank being configured to keep a heat transfer fluid in liquid form, the electronic device being immersed in the tank. In addition, there is a vapor space above the surface of the liquid heat transfer fluid. Arranged outside the pressure-sealed tank is a condenser, wherein the condenser has an inlet, the inlet is connected to the vapor space by a riser, and is configured to receive heat transfer fluid vapor. In addition, the condenser has a tightly closable 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 flow through it, flowing back to the tank from the condensate outlet. In the tank, there may also be another condenser tube for liquefying the gaseous heat transfer fluid.

[0007] The underlying object of the present invention is to further develop a cooling system for liquid immersion cooling of electronic components with respect to a heat exchanger arrangement for a heat transfer fluid.

[0008] The invention is characterized by the features of claim 1. Further dependent claims relate to advantageous embodiments and developments of the invention.

[0009] The present invention comprises a cooling system for liquid immersion cooling of electronic components. The cooling system comprises a container, the interior of which can be filled with a two-phase heat transfer fluid, and the electronic components can be immersed in the liquid phase of the container. The container has a gas space above the surface of the liquid heat transfer fluid. In addition, the cooling system comprises a heat exchanger device in the gas space of the container for the purpose of forming the liquid heat transfer fluid. The cooling system also comprises a condenser unit arranged outside the container, wherein the condenser unit is connected to the gas space of the container via fluid lines as feed lines and return lines for mass transfer of the gaseous medium to the condenser unit and mass transfer of the condensed heat transfer fluid to the container, wherein the condenser unit has an outlet through which the residual gas phase can be discharged. According to the present invention, the fluid lines as feed lines and return lines of the condenser unit are single-tube lines or double-tube lines with suitable line cross-sections connected to the container.

[0010] The container may be of a pressure-tight design. The container may advantageously be embodied as a pressure vessel that can operate under vacuum and / or overpressure. By controlling the pressure in the container in which the cooling system operates, an increased cooling capacity may be achieved.

[0011] The heat exchanger arrangement in the gas space preferably consists of at least one tube bundle, which comprises a plurality of heat exchanger tubes arranged relative to one another. The tube bundle can have a plurality of heat exchanger tubes arranged parallel to one another, with two tube sheets at the ends. In the vessel, the tube bundle or the heat exchanger tubes can be arranged symmetrically or alternatively asymmetrically or diagonally relative to the vessel wall.

[0012] The feed and return lines of the condenser unit can also be single-tube lines with suitable line cross sections connected to the container. The mass transfer of the gaseous medium and the mass transfer of the condensed heat transfer fluid both occur via the single-tube line. Here, the size of the suitable line cross section is determined in such a way that the gaseous and liquid media flowing in opposite directions in the same tube do not hinder each other in terms of their flow characteristics. Practical experience shows that due to the wetting characteristics, the condensed heat transfer fluid flows along the inner tube wall to the container, and the gaseous heat transfer fluid flows in the opposite direction to the condenser in the central area of ​​the tube.

[0013] Alternatively, the feed and return lines of the condenser unit can also be double-tube lines connected to the container. The mass transfer of the gaseous medium takes place via the internal feed line and the mass transfer of the heat exchange fluid for condensation takes place via the return line surrounding the internal feed line. In this case, suitable line cross sections of the feed and return lines are dimensioned in such a way that the gaseous and liquid media flowing in the corresponding lines can flow with low resistance in their flow characteristics. Practical experience has shown that, due to the smaller volume, the condensed heat transfer fluid requires a smaller line cross section of the shell tube of the return line than the line cross section of the internal feed line of the gaseous heat transfer fluid.

[0014] The heat exchanger tubes are preferably ribbed tubes which are produced from smooth tubes and subjected to a forming process. They are particularly suitable as components in 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. With a large selection of materials including copper, copper alloys, steel, titanium or titanium alloys, it is ensured that suitable materials for the corresponding requirements, especially in terms of durability and deformability, are available for different needs.

[0015] The two-phase heat transfer fluid, also called refrigerant, forms the outer fluid located in the container, in the liquid part of which the electronic components are immersed. The inner fluid located in the heat exchanger tubes is usually a single-phase heat transfer medium, for example, process water, glycol or heat transfer oil. However, also in this case, the two-phase medium can be used in combination with a refrigeration circuit.

[0016] In the container, the electronic components are arranged in a manner suitable for cooling in a bath of liquid heat transfer fluid and are cooled by evaporation of the liquid fluid. During this process, the gas portion that cannot be condensed can be effectively removed from the system before or during startup.

[0017] In embodiments according to the invention, computing components and immersion cooling equipment, as well as associated power supplies, network connections, cabling connections, etc., may be arranged in a container having an internal pressure that deviates from ambient pressure during operation.

[0018] In this context, it is also advantageous to combine electricity, water, vacuum and network connections in one bundle of lines in order to minimize access to the container and to reduce the risk of leaks, especially if the system is under vacuum or excessive pressure during operation.

[0019] In an advantageous embodiment, the container is maintained at up to 200 hPa below ambient atmospheric pressure during operation, and this helps to lower the boiling point of the two-phase heat transfer fluid and thereby lower the operating temperature of computer chips and other components. In many specific embodiments, the pressure-controlled container can have an even lower pressure of up to 500 hPa below ambient pressure.

[0020] Embodiments of cooling systems according to the present invention include containers that are designed in a manner such that a two-phase liquid immersion cooling system is used. The container comprises a trough of a dielectric cooling fluid, a heat exchanger device, and an external condenser unit for condensing the dielectric fluid from the gas phase into a liquid. The condenser unit located outside the container is intended to condense the residue of the gaseous heat transfer fluid (also containing some parts of air and water vapor) into a portion of liquid heat transfer fluid as high as possible. Ideally, the residual heat transfer fluid is almost completely condensed from the gas phase, leaving only air and water vapor as the residual gas phase. The purpose of precipitating the liquid heat transfer fluid here is to keep water vapor in the gas phase by the suitable cooling capacity of the system. The residual gas mixture is discharged from the cooling system via the outlet of the condenser unit.

[0021] In addition, devices for holding computer components and for distributing power from the power system to the equipment and components located in the container can be provided. It goes without saying that a large number of dedicated connections are used to operate computer systems in containers such as those maintained under vacuum. Some embodiments of the system according to the present invention can use a series of fiber optic interfaces that allow connectivity in the container and distribute optical fibers between various holding devices to electronic components. Some embodiments of the container can include monitoring sensors for reliable operation. These sensors can include temperature sensors, liquid level sensors, pressure sensors, position sensors, electrical sensors and / or cameras to ensure and automate the operation of the system.

[0022] These systems may include, for example, pressure sensors within the pressure controlled container that monitor the pressure to ensure that there is no significant leak. Gas sensors may also be provided that are arranged external to the pressure controlled container and detect the presence of any dielectric vapor that may be present and escape from the pressure controlled container.

[0023] Furthermore, the cooling system may advantageously have a control device which is designed to control the operation of the fluid circulation system, for example, depending on the temperature of the two-phase heat transfer fluid and the pressure conditions in the container.

[0024] An assembly system can advantageously be provided by which the electronic components can be transported from the locking device to the operating position for replacement. The assembly system can include a robotic arm or a linear drive. Given a suitable design of the device, the replacement of these components can be performed by a fully automatic assembly system. Alternatively, gloves can also be arranged at a suitable container opening to allow the electronic components to be transferred from the locking device to the operating position. This enables assembly by manual access to the interior of the container.

[0025] In an advantageous embodiment of the invention, the fluid line can have a structured inner surface. In the case of a single-tube line, the inner surface can have ribbed, channeled or porous structural features or raised portions, through which the condensed heat transfer fluid is guided along the surface of the inside of the tube to the container inlet. In the case of a double-tube line routed to the container, the inner surface of the return line located inside is of ribbed, channeled or porous design, or is designed with raised portions to selectively guide the condensed heat transfer fluid away in the same manner. Conversely, the inner surface of the outer tube surrounding the return line can also have a smooth design for carrying the gaseous heat transfer fluid.

[0026] In a particularly advantageous embodiment of the cooling system according to the invention, the structured inner surface of the fluid conduit can spirally surround the ribs to guide the condensed heat transfer fluid to the container. Given an appropriate pitch of the ribs, the fluid can be guided in a spiral manner by means of gravity on the inner tube wall.

[0027] In an advantageous embodiment, the fluid line can be a line extending at an inclined angle relative to the effect of gravity or a double line. Thus, due to gravity, the condensed heat transfer fluid flows back onto at least a portion of the inner wall of the container. In the case of a single-line line, the mass transfer of the condensed heat transfer fluid thus takes place in the lower part of the inner wall, while the gaseous heat transfer fluid is guided in a countercurrent flow along the upper part of the inner wall.

[0028] The angle of inclination of the fluid line relative to the effect of gravity is advantageously at least 2°, and preferably at least 5°, and particularly preferably at least 15°. Even with such a small angle of inclination, it is prevented that the condensed heat transfer fluid accidentally falls freely and in an uncontrolled manner into the interior of the tube during its return to the container. In particular in the case of a single-tube line, it is possible to suppress uncontrolled flows or turbulences which would disrupt the counterflow of the gaseous heat transfer fluid.

[0029] In a preferred embodiment of the invention, the feed line, the return line and / or the outlet can be closable or openable by valves, either individually or in combination with one another. For suitable process management, individual valves are opened when necessary to transfer gaseous media or liquid heat transfer fluid. The feed and / or discharge can occur cyclically or in a continuous mode. In particular, the valve switching at the outlet is adjusted to ensure that as little as possible or even no heat transfer fluid escapes from the cooling system.

[0030] In an advantageous embodiment of the invention, a collecting container is connected downstream of the outlet, via which the residual gas phase can be discharged. The container ensures that no air can enter the cooling system from the environment. The container can be an expandable elastic bladder or a bellows of variable volume.

[0031] A drying unit for separating water vapor from the gas phase can advantageously be arranged between the outlet and the collecting container. For example, in the event of a load reversal, the pressure conditions in the entire cooling system can change. If necessary, outside air or residual gas can then be introduced into the cooling system via the collecting container, via the drying unit, for pressure compensation. The water vapor is then removed by chemical bonding via the drying unit. Silica gel is suitable for such a drying unit.

[0032] In an advantageous embodiment of the invention, a vacuum pump is connected downstream of the outlet, via which the residual gas phase can be discharged. In this case, the residual gas phase consisting of water vapor and air can also be under vacuum at the outlet relative to the environment, since the flow direction of the residual gas towards the outside is always ensured by means of the vacuum pump.

[0033] The heat exchanger device and the condenser unit may advantageously have a common supply unit of a single-phase heat transfer medium for cooling purposes. Thus, both units are at a single temperature level suitable for the process of separating out the heat exchanger fluid.

[0034] The distribution of the amount of the single-phase heat transfer medium for the cooling of the heat exchanger arrangement and the condenser unit of the common supply unit can advantageously be achieved by active control of the volume flow of the single-phase heat transfer medium.

[0035] A multiway valve, in particular a three-way valve, is particularly suitable for active control of the volume flow. Alternatively or in combination, it is also possible to combine a limiter or a frequency-controlled pump for controlling the volume flow into the supply unit. It is thereby possible to match and control the cooling capacity of the heat exchanger device and of the condenser unit relative to one another in a suitable manner via the supply unit.

[0036] In an advantageous embodiment of the invention, the cooling device can be arranged at least partially on the fluid line. This can be a cooling tube or a cooling jacket wound helically around the fluid line. This is an effective means of preventing the liquid fluid from being reheated beyond the boiling point by the hotter gaseous fluid flowing in the opposite direction. In particular, the temperature of the liquid fluid flowing along the inner wall of the fluid line is further reduced in this way.

[0037] Exemplary embodiments of the invention are explained in more detail with the aid of the schematic drawings.

[0038] In the attached picture:

[0039] Figure 1 shows a schematic diagram of a cooling system having a condenser unit and pipes as fluid lines, and

[0040] Figure 2 Another schematic diagram of a cooling system with a condenser unit and a double-pipe line as fluid line is shown.

[0041] In all the figures, mutually corresponding parts are provided with the same reference symbols.

[0042] Figure 1 A schematic diagram of a cooling system 1 is shown, which comprises a condenser unit 8 and a pipe 7 as a fluid pipe for liquid immersion cooling of an electronic component 2. The cooling system 1 comprises a container 3, which is filled internally with a two-phase heat transfer fluid during operation. The two-phase heat transfer fluid represents an external fluid located in the container 3, having a liquid heat transfer fluid portion 4 and a gas space 5 containing a gaseous heat transfer fluid portion, wherein the electronic component 2 is immersed in the liquid heat transfer fluid portion. In the container 3, a heat exchanger device 6 is arranged in the gas space 5 of the container 3 for the purpose of forming the liquid heat transfer fluid 4.

[0043] In this advantageous embodiment, the heat exchange device 6 in the gas space 5 consists of tube bundles 61 , each of which has a plurality of heat exchange tubes arranged parallel to one another.

[0044] exist Figure 1 In the embodiment shown in , the container 3 is slightly conical in the area of ​​the liquid heat transfer fluid 4, since the container walls project inwards and are open only in the gas space 5. The shape of the container 3 is supported by the metal profile frame 31. The container 3 is thus already surrounded by a stable outer frame.

[0045] The condenser unit 8 is arranged outside the container 3 and above the container. The condenser unit 8 is connected to the gas space 5 of the container 3 via fluid lines 7 as feed lines 71 and return lines 72 for mass transfer of gaseous medium and condensed heat transfer fluid between the container 3 and the condenser unit 8. Figure 1 In the variant shown in FIG. 1 , the fluid lines 7 as feed lines 71 and return lines 72 of the condenser unit 8 are embodied in the form of single-tube lines with a suitable line cross section.

[0046] For the purpose of controlling the mass transfer, a valve 700 is optionally installed in the fluid line 7. Via the valve 700, a gaseous mixture of substances consisting of heat transfer fluid, air and water vapor is in this way cyclically or continuously withdrawn from the container 3. Via the same valve 700, the liquid heat transfer fluid returns to the container 3.

[0047] exist Figure 1 , a cooling device 73 is arranged on the fluid line 7. In the embodiment shown, the cooling device 73 is a cooling sleeve through which a coolant flows during operation in order to additionally cool the outside of the fluid line 7 and, therefore, the liquid fluid flowing inside. In particular, the liquid fluid in contact with the inner wall of the fluid line 7 is effectively kept at a temperature below the boiling point in this way.

[0048] The residual gas phase can be supplied to the collecting container 9, which can be designed as a bellows for generating a vacuum expandable volume, via a feed line 91 with a valve 910. If the valve 910 to the collecting container 9 is closed during operation, the residual gas can be discharged via the discharge line 92 of the collecting container 9 when the valve 920 is opened.

[0049] In order to additionally separate the water vapor, a drying unit 11 for separating the water vapor from the gas phase is arranged between the outlet 81 and the collecting container 9. Depending on the pressure conditions, the residual gas phase can be discharged directly into the environment.

[0050] Alternatively, however, the residual gas phase can also be discharged via the vacuum pump 10. For this purpose, the outlet 81 is connected via a feed line 101 to the vacuum pump 10, which controls the residual gas flow to the outside via a discharge line 102 of the vacuum pump 10 via a valve control arrangement 1010.

[0051] Figure 2 1 shows a schematic diagram of a cooling system 1 comprising a condenser unit 8 and a double-tube line 7 as a fluid line for liquid immersion cooling of electronic components 2. Figure 1In an alternative to the embodiment shown in FIG. 1 , the double-tube pipeline serves as a feed line 71 for the gaseous medium to the condenser unit 8 and as a return line 72 for the condensed heat transfer fluid to the condenser unit 8, which is connected to the container 3. The mass transfer of the gaseous medium occurs via the internal feed line 71. The mass transfer of the condensed heat transfer fluid occurs via the return line 72 surrounding the internal feed line 71. In this arrangement, the internal feed line 71 can be slightly longer than the surrounding return line 72 at the entrance to the condenser unit 8. This ensures that during operation of the system, the condensed heat transfer fluid only enters the return line 72 and does not accidentally enter the feed line 71, which extends into the condenser unit 8.

[0052] Feed line 71 can be closed and opened individually by valve 710, feed line 72 can be closed and opened individually by another valve 720, or they can be closed and opened in combination. For appropriate process management, individual valves are opened when necessary to pass gaseous media or liquid heat transfer fluid.

[0053] List of Reference Numerals

[0054] 1 Cooling system

[0055] 2 Electronic components

[0056] 3 Container

[0057] 31 Metal profile frame

[0058] 4 Liquid heat transfer fluid

[0059] 41 Surface of liquid fluid in container

[0060] 5 Gaseous heat transfer fluid, gas space

[0061] 6 Heat exchange device

[0062] 61 Discipline

[0063] 7 Fluid lines

[0064] 700 Valves for fluid lines

[0065] 71 Feed line

[0066] 710 Valve for feed line

[0067] 72 Return line

[0068] 720 Return line valve

[0069] 73 Cooling device

[0070] 8 Condenser unit

[0071] 81 Exit

[0072] 810 Outlet valve

[0073] 9 Collection container, bellows

[0074] 91 Feed pipeline, collection container

[0075] 910 Valve, collecting container for feed line

[0076] 92 Discharge pipeline, collection container

[0077] 920 Valve, collecting container for discharge line

[0078] 10 Vacuum pump

[0079] 101 Feed pipeline, vacuum pump

[0080] 1010 Valve and vacuum pump for feed line

[0081] 102 Exhaust pipeline, vacuum pump

[0082] 11 Drying unit

Claims

1. A cooling system (1) for liquid immersion cooling of electronic components (2), the cooling system comprising: - a container (3), the interior of which is filled with a two-phase heat transfer fluid (4), the electronic component (2) being able to be immersed in the liquid phase of the container, wherein the container (3) has a gas space (5) above the surface (41) of the liquid heat transfer fluid (4), - a heat exchanger device (6) in the gas space (5) of the container (3) for the purpose of forming a liquid heat transfer fluid (4), - a condenser unit (8), arranged outside the container (3), The condenser unit (8) is connected to the gas space (5) of the container (3) via fluid lines (7) as feed lines (71) and return lines (72) for transferring the mass of the gaseous medium to the condenser unit (8) and transferring the mass of the condensed heat transfer fluid to the container (3), wherein the condenser unit (8) has an outlet (81) through which the residual gas phase can be discharged, characterized in that - The fluid lines (7) as feed lines (71) and return lines (72) of the condenser unit (8) are single-tube or double-tube lines with suitable line cross sections connected to the container (3).

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

3. The cooling system (1) according to claim 2, characterized in that The structured inner surface of the fluid line (7, 71, 72) has ribs which circumvent in a helical manner.

4. Cooling system (1) according to one of claims 1 to 3, characterized in that The fluid pipeline (7, 71, 72) is a pipeline or a double-tube pipeline extending at an inclined angle relative to the action of gravity.

5. The cooling system (1) according to claim 4, characterized in that The fluid pipeline (7, 71, 72) has an inclination angle of at least 2° relative to the effect of gravity.

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

7. Cooling system (1) according to one of claims 1 to 6, characterized in that A collecting container (9) is connected downstream of the outlet (81), via which the residual gas phase can be discharged.

8. The cooling system (1) according to claim 7, characterized in that A drying unit (11) for separating water vapor from the gas phase is arranged between the outlet (81) and the collecting container (9).

9. The cooling system (1) according to any one of claims 1 to 6, characterized in that Connected downstream of the outlet ( 81 ) is a vacuum pump ( 10 ), via which the residual gas phase can be discharged.

10. The cooling system (1) according to any one of claims 1 to 9, characterized in that The heat exchanger device (6) and the condenser unit (8) have a common supply of a single-phase heat transfer medium for cooling purposes.

11. The cooling system (1) according to claim 10, characterized in that By means of active control of the volume flow of the single-phase heat transfer medium, a quantity distribution of the single-phase heat transfer medium for cooling the heat exchanger device (6) and the condenser unit (8) of the common supply unit is achieved.

12. The cooling system (1) according to any one of claims 1 to 11, characterized in that The cooling device (73) is at least partially arranged on the fluid line (7).

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