Cooling system for the liquid immersion cooling of electronic components

Abstract

The invention relates to a cooling system for the liquid immersion cooling of electronic components (2), the cooling system comprising - a vessel (3), the interior of which can be filled with two-phase heat transfer fluid (4), in the liquid phase of which electronic components (2) can be immersed, the vessel (3) having 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 vessel (3) for the purposes of forming liquid heat transfer fluid (4), - a condenser unit (8) arranged outside the vessel (3), the condenser unit (8) being connected by means of a fluid line (7) as the feed line (71) and return line (72) to the gas space (5) of the vessel (3) for the mass transfer of gaseous medium to the condenser unit (8) and condensed heat transfer fluid to the vessel (3), the condenser unit (8) having an outlet (81) via which a residual gas phase can be discharged, and - the fluid line (7) as the feed line (71) and return line (72) of the condenser unit (8) is a single tube line with a suitable line cross-section or a double-tube line which is connected to the vessel (3).

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] Liquid immersion cooling systems, such as two-phase immersion cooling systems, are an active cooling solution for electronic components that generate a lot of heat during operation. When the components are immersed in a two-phase heat transfer fluid, which usually has a low boiling point, the heat generated by the electronic component can evaporate the surrounding liquid heat transfer fluid, thereby removing heat from the electronic component. A condenser device liquefies the gaseous heat transfer fluid, which is then returned to the reservoir for cooling.

[0005] A two-phase immersion cooling system with a cooling basin is known from US Pat. No. 10,512,192 B2. A condensation chamber, in which the gaseous fluid produced during the cooling process is condensed, communicates with the liquid fluid in the cooling basin. A vapor diversion structure is arranged above the heat-generating electronic components located within the cooling medium in the cooling basin. The vaporized fluid is directed into the condensation chamber for condensation by means of the vapor diversion structure. The condensation chamber is located entirely within the cooling basin. In this context, a cooling system for computer components is known from US Pat. No. 10,477,726 B1. A pressure-controlled container contains a heat-conducting, dielectric heat transfer fluid in liquid and gaseous phases, which 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. A condenser condenses the dielectric gas-phase fluid evaporated by the heat generated by the computer components into a dielectric liquid-phase fluid. The internal pressure in the pressure-controlled container is reduced to as low as 650 hPa. By controlling the pressure in the container at which the system operates, the user can influence the temperature at which the dielectric fluid evaporates. This can achieve increased cooling performance. Operating a computer system within a pressure-controlled container at an operating pressure that differs from ambient pressure usually requires a structural modification of the system as a whole.

[0006] From the publication US 2021 / 0 153 392 A1, a cooling system is known comprising a container that can be filled with a two-phase heat transfer fluid as a coolant, into whose liquid phase electronic components can be immersed. The container has a gas space above the surface of the liquid heat transfer fluid. A separate external condenser device is arranged above the container and is configured to condense the vapor phase of the heat transfer fluid and return it as a liquid coolant to the container containing the electronic components. For this purpose, the system comprises return and supply lines connected to both the condenser device and the container to form a heat exchange loop.The system also includes a storage tank located on the supply line and configured to collect the condensed liquid heat transfer fluid before the coolant is fed to the reservoir. This accumulator also provides reserve cooling capacity for the cooling system.

[0007] From the document EP 3 453 235 B1, a cooling system for immersion cooling of electronic components is known, comprising a pressure-tight tank configured to contain heat transfer fluid in liquid form, into which the electronic equipment is immersed. Furthermore, a vapor space is present above a surface of the liquid heat transfer fluid. A condenser is arranged outside the pressure-tight tank, wherein the condenser has an inlet connected to the vapor space by a riser pipe and configured to receive heat transfer fluid vapor. Furthermore, the condenser has a tightly sealable vapor outlet for residual gases and a condensate outlet with a condensate return line to the tank. The condensate return line is configured to allow condensed heat transfer fluid to flow back from the condensate outlet to the tank.Additional condenser tubes for liquefying gaseous heat transfer fluid may also already be present within the tank.

[0008] The invention is based on the object of developing a cooling system for liquid immersion cooling of electronic components with respect to a heat exchanger device for the heat transfer fluid.

[0009] The invention is defined by the features of claim 1. The further dependent claims relate to advantageous embodiments and developments of the invention.

[0010] The invention includes 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, into whose liquid phase electronic components can be immersed. The container has a gas space above the surface of the liquid heat transfer fluid. Furthermore, the cooling system comprises a heat exchanger device in the gas space of the container for forming liquid heat transfer fluid. The cooling system also comprises a condenser unit arranged outside the container. The condenser unit is connected to the gas space of the container by means of a fluid line serving as a supply line and a return line for mass transfer of gaseous medium to the condenser unit and condensed heat transfer fluid to the container. The condenser unit has an outlet through which a residual gas phase can be discharged.According to the invention, the fluid line as supply line and return line of the condenser unit is a single pipe with a suitable pipe cross-section or a double pipe which is connected to the container.

[0011] The container can be designed to be pressure-tight. Advantageously, the container can be designed as a pressure vessel that can be operated at negative and / or positive pressure. By controlling the pressure in the container at which the cooling system operates, increased cooling performance can be achieved.

[0012] The heat exchanger device in the gas space preferably consists of at least one tube bundle consisting of several heat exchanger tubes arranged relative to one another. A tube bundle can have several heat exchanger tubes arranged parallel to one another with two end tube plates. The arrangement of the tube bundles or heat exchanger tubes in the vessel can be symmetrical or asymmetrical with respect to the vessel wall, or along slopes. The supply line and the return line of the condenser unit can also be a single pipe with a suitable cross-section, which is connected to the vessel. Such that both a mass transfer of gaseous medium and a mass transfer of condensed heat transfer fluid take place via this single pipe.A suitable pipe cross-section is dimensioned so that the gaseous and liquid media flowing in opposite directions within the same pipe do not impede each other's flow characteristics. Practical experience shows that, due to its wetting properties, condensed heat transfer fluid flows along the inner pipe wall toward the vessel, while gaseous heat transfer fluid flows toward the condenser in the opposite direction in the center of the pipe.

[0013] Alternatively, the supply line and return line of the condenser unit can also be a double pipe connected to the vessel. This allows mass transfer of gaseous medium via an internal supply line and mass transfer of condensed heat transfer fluid via a return line surrounding the internal supply line. A suitable cross-section of the supply line and the return line is dimensioned so that the gaseous and liquid media flowing in the respective line can flow with low resistance in their flow characteristics. Practical experience shows that, due to its smaller volume, condensed heat transfer fluid requires a smaller cross-section of the return line jacket pipe than the cross-section of the internal supply line for gaseous heat transfer fluid.

[0014] The heat exchanger tubes are preferably finned tubes, which are made from smooth tubes and subjected to a forming process. They are particularly suitable as components in highly efficient, compact, and extremely stable heat exchangers with a high heat transfer coefficient. The tube surfaces are optimized for the specific heat transfer requirements of the application. A wide selection of materials, including copper, copper alloys, steels, titanium, and titanium alloys, ensures that suitable materials are available for different needs, particularly in terms of durability and formability.

[0015] The two-phase heat transfer fluid, also known as the refrigerant, represents the outer fluid in the vessel, in whose liquid portion the electronic components are immersed. The inner fluid in the heat exchanger tubes is typically a single-phase heat transfer medium, such as process water, glycol, or thermal oil. However, a two-phase medium can also be used here in conjunction with a refrigeration circuit.

[0016] In the vessel, the electronic components are arranged in a suitable manner in a bath of liquid heat transfer fluid, which is cooled by evaporation of the liquid fluid. This allows the proportion of non-condensable gases to be effectively removed from the system before or during commissioning.

[0017] In the embodiment according to the invention, the computing components and immersion cooling devices as well as the associated power supplies, network connections, wiring connections and the like can be arranged in the container, which has an internal pressure that differs from the ambient pressure during operation.

[0018] In this context, it is also advantageous to combine power, water, vacuum and network connections in a bundle of lines to minimize penetrations into the vessel and to reduce the risk of leaks, especially when the system is under vacuum or overpressure during operation.

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

[0020] Embodiments of the cooling system according to the invention comprise a vessel designed to utilize a two-phase liquid immersion cooling system. The vessel contains a basin of dielectric cooling fluid, a heat exchanger device, and an external condenser unit for condensing the dielectric fluid from the gaseous phase to a liquid. The condenser unit located outside the vessel is intended to condense the remaining gaseous heat transfer fluid, which also contains certain amounts of air and water vapor, into as large a proportion as possible of liquid heat transfer fluid. Ideally, the remaining heat transfer fluid is almost completely condensed from the gas phase, so that essentially only air and water vapor remain as the residual gas phase. The goal of separating liquid heat transfer fluid is to keep the water vapor in the gas phase through suitable cooling capacity of the system.This residual gas mixture is discharged from the cooling system via an outlet of the condenser unit.

[0021] Additionally, devices for holding computer components and distributing power from the power system to the devices and components located within the container may be provided. It is understood that a variety of specialized connections are used to operate a computer system within a container, for example, maintained at a vacuum. Some embodiments of the system according to the invention may utilize a series of fiber optic interfaces to enable connectivity within the container and to distribute the fibers to the various holding devices for the electronic components. Some embodiments of the container 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.

[0022] These systems may, for example, include pressure sensors inside the pressure-controlled vessel that monitor the pressure to ensure there are no significant leaks. Gas sensors located on the outside of the pressure-controlled vessel may also detect the presence of any dielectric vapor escaping from the pressure-controlled vessel.

[0023] In addition, the cooling system may advantageously comprise a control device designed to regulate the operation of the fluid circulation, for example as a function of the temperature of the two-phase heat transfer fluid, and the pressure conditions in the container.

[0024] Advantageously, a placement system can be set up that allows the electronic components to be transported from the lock device to the operating position for replacement. A placement system can consist of robotic arms or linear drive devices. With a suitable design of the device, the components can be replaced using a fully automated placement system. Alternatively, gloves can be placed at suitable container openings for replacing the electronic components from the lock device to the operating position. This allows for 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 pipe, the inner surface can have rib-like, channel-like, porous structural features or elevations, by means of which the condensed heat transfer fluid is guided along the surface of the inner pipe side to the tank inlet. In the case of a double pipe leading to the tank, the inner surface of the internal return line is designed to be rib-like, channel-like, porous, or with elevations in order to specifically discharge the condensed heat transfer fluid in the same way. In contrast, the inner surface of the outer pipe enclosing the return line for conducting the gaseous heat transfer fluid can also be smooth.

[0026] In a particularly advantageous embodiment of the cooling system according to the invention, the structured inner surface of the fluid line can be a helically extending finning system for conveying the condensed heat transfer fluid to the container. With a suitable fin pitch, the fluid is guided in a spiral along the inner tube wall by gravity.

[0027] In an advantageous embodiment, the fluid line can be a pipeline or double pipeline that runs at an angle to the force of gravity. This causes condensed heat transfer fluid to flow back to the vessel due to gravity, at least over part of the inner wall. With a single pipeline, the condensed heat transfer fluid flows along the lower part of the inner wall, whereas the gaseous heat transfer fluid flows in countercurrent along the upper part of the inner wall.

[0028] Advantageously, the angle of inclination of the fluid line relative to the force of gravity can be at least 2°, preferably at least 5°, and particularly preferably at least 15°. Even such small angles of inclination prevent condensed heat transfer fluid from undesirably falling freely and uncontrollably through the interior of the pipe during its return to the vessel. Especially with a single pipe, uncontrolled or turbulent flow can be prevented, which would disrupt the counterflow of the gaseous heat transfer fluid.

[0029] In a preferred embodiment of the invention, the supply lines, return lines, and / or the outlet can be closed or opened individually or in combination with one another by valves. For suitable process control, individual valves are opened as needed to convey gaseous medium or liquid heat transfer fluid. The supply or discharge can occur cyclically or continuously. In particular, the valve circuit at the outlet is designed to ensure that as little or no heat transfer fluid as possible escapes from the cooling system.

[0030] In an advantageous embodiment of the invention, a collecting container can be arranged downstream of the outlet, through which the residual gas phase can be discharged. This container ensures that no air from the environment can enter the cooling system. The container can be an expandable, elastic balloon or a bellows with a variable volume. Advantageously, a drying unit can be arranged between the outlet and the collecting container to separate water vapor from the gas phase. For example, when the load changes, the pressure level in the entire cooling system changes. If necessary, outside air or residual gas can then be introduced into the cooling system via the collecting container to equalize the pressure. Water vapor is then chemically bound by the drying unit. Silica gel is suitable for such drying units.

[0031] In an advantageous embodiment of the invention, a vacuum pump can be arranged downstream of the outlet, via which the residual gas phase can be removed. In this case, the residual gas phase consisting of water vapor and air at the outlet can also be at a negative pressure compared to the ambient air, since a vacuum pump always ensures that the residual gas flows outward.

[0032] Advantageously, the heat exchanger unit and the condenser unit can have a common supply unit for a single-phase heat transfer medium for cooling. This ensures that both units are at a uniform temperature level, which is suitable for the separation process of the heat exchanger fluid.

[0033] Advantageously, the quantity distribution of the single-phase heat transfer medium for cooling the heat exchanger device and the condenser unit of the common supply unit can be carried out by means of an active control of the volume flow of the single-phase heat transfer medium.

[0034] A multi-way valve, especially a three-way valve, is particularly suitable for actively controlling the flow rate. Alternatively, or in combination, a throttle or a frequency-controlled pump can also be integrated into the supply unit to regulate the flow rate. This allows the cooling capacities of the heat exchanger and the condenser unit to be appropriately coordinated and controlled via a supply unit.

[0035] In an advantageous embodiment of the invention, a cooling device can be arranged at least partially along the fluid line. This can be a cooling tube spirally wound around the fluid line or a cooling sleeve. This effectively prevents the liquid fluid from reheating beyond its boiling point due to the warmer 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.

[0036] Embodiments of the invention are explained in more detail with reference to the schematic drawings.

[0037] Showing:

[0038] Fig. 1 is a schematic view of a cooling system with a condenser unit and a pipeline as a fluid line, and

[0039] Fig. 2 is another schematic view of a cooling system with a condenser unit and double pipe as fluid line.

[0040] Corresponding parts are provided with the same reference numerals in all figures.

[0041] Fig. 1 shows a schematic view of a cooling system 1 with

[0042] Condenser unit 8 and a pipe 7 as a fluid line to

[0043] Liquid immersion cooling of electronic components 2. The cooling system 1 comprises a container 3, which is filled with a two-phase heat transfer fluid during operation. The two-phase heat transfer fluid represents the external fluid located in the container 3, with a liquid heat transfer fluid portion 4 in which the electronic components 2 are immersed and a gas space 5 containing a gaseous heat transfer fluid portion. A heat exchanger device 6 is arranged in the gas space 5 of the container 3 to form liquid heat transfer fluid 4.

[0044] In this advantageous embodiment, the heat exchanger device 6 in the gas space 5 consists of tube bundles 61, each with a plurality of heat exchanger tubes arranged parallel to one another.

[0045] In the illustrated embodiment in Fig. 1, the container 3 is slightly tapered in the area of ​​the liquid heat transfer fluid 4, with the container wall projecting inward and only opening in the gas space 5. The shape of the container 3 is supported by a metal profile frame 31. The container 3 is therefore already enclosed by a stabilizing outer frame.

[0046] A condenser unit 8 is arranged outside the container 3 above it. The condenser unit 8 is connected to the gas space 5 of the container 3 by means of a fluid line 7 serving as a supply line 71 and a return line 72 for mass transfer of gaseous medium and condensed heat transfer fluid between the container 3 and the condenser unit 8. In the variant shown in Fig. 1, the fluid line 7 serving as a supply line 71 and a return line 72 of the condenser unit 8 is designed in the form of a single pipe with a suitable cross-section.

[0047] To regulate the mass transfer, a valve 700 is optionally installed in the fluid line 7. A gaseous mixture of heat transfer fluid, air, and water vapor is withdrawn from the vessel 3 cyclically or continuously via the valve 700. Liquid heat transfer fluid is returned to the vessel 3 via the same valve 700.

[0048] In Fig. 1, a cooling device 73 is arranged on the fluid line 7. In the illustrated embodiment, the cooling device 73 is a cooling sleeve through which a coolant flows during operation to further cool the outside of the fluid line 7 and thus the liquid fluid flowing on the inside. In particular, the liquid fluid in contact with the inner wall of the fluid line 7 is effectively kept below its boiling point in this way.

[0049] The residual gas phase can be fed via a supply line 91 with valve 910 to a collecting tank 9, which can be designed as a volume-expanding bellows to generate a negative pressure. If the valve 910 to the collecting tank 9 is closed during operation, the residual gas can be discharged via the discharge line 92 of the collecting tank 9 with the valve 920 open.

[0050] For additional separation of water vapor, a drying unit 11 is arranged between outlet 81 and collection tank 9 to separate water vapor from the gas phase. Depending on the pressure level, the residual gas phase can be discharged directly to the environment.

[0051] Alternatively, the residual gas phase can also be removed via a vacuum pump 10. For this purpose, the outlet 81 is connected via a supply line 101 to a vacuum pump 10, which, via a valve control 1010, regulates the residual gas flow to the outside via a discharge line 102 of the vacuum pump 10.

[0052] Fig. 2 shows a schematic view of a cooling system 1 with

[0053] Condenser unit 8 and a double pipe 7 as a fluid line for liquid immersion cooling of electronic components 2. As an alternative to the embodiment according to Fig. 1, the double pipe serves as a supply line 71 for gaseous medium to the condenser unit 8 and as a return line 72 for condensed heat transfer fluid from the condenser unit 8, which is connected to the container 3. The mass exchange of gaseous medium takes place via the internal supply line 71. The mass exchange for condensed heat transfer fluid takes place via a return line 72 surrounding the internal supply line 71. In this case, the internal supply line 71 can be designed to be somewhat longer than the surrounding return line 72 at the inlet to the condenser unit 8.In this way, during operation of the system, the condensed heat transfer fluid flows exclusively into the return line 72 and not undesirably into the supply line 71, which projects into the condenser unit 8.

[0054] The supply line 71 can be closed or opened individually or in combination by a valve 710, and the return line 72 can be opened or closed individually or in combination by a further valve 720. For suitable process control, individual valves are opened as needed to convey gaseous medium or liquid heat transfer fluid.

[0055] List of reference symbols

[0056] 1 cooling system

[0057] 2 electronic component

[0058] 3 containers

[0059] 31 metal profile frames

[0060] 4 liquid heat transfer fluid

[0061] 41 Surface of the liquid fluid in the container

[0062] 5 gaseous heat transfer fluid, gas space

[0063] 6 Heat exchanger device

[0064] 61 tube bundles

[0065] 7 Fluid line

[0066] 700 Fluid line valve

[0067] 71 Supply line

[0068] 710 Supply line valve

[0069] 72 Return line

[0070] 720 Return line valve

[0071] 73 Cooling device

[0072] 8 Capacitor unit

[0073] 81 Outlet

[0074] 810 exhaust valve

[0075] 9 collecting container, bellows

[0076] 91 Supply line collection container

[0077] 910 Valve of the supply line collection tank

[0078] 92 Discharge line collection container

[0079] 920 Valve of the discharge line collection tank 10 Vacuum pump

[0080] 101 Vacuum pump supply line

[0081] 1010 Valve of the supply line vacuum pump 102 Discharge line vacuum pump

[0082] 11 Drying unit

Claims

Patent claims 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 heat exchanger device (6) in the gas space (5) of the container (3) for forming liquid heat transfer fluid (4), - a condenser unit (8) which is arranged outside the container (3), wherein the condenser unit (8) is connected by means of a fluid line (7) as a supply line (71) and return line (72) to the gas space (5) of the container (3) for the mass exchange of gaseous medium to the condenser unit (8) and condensed heat transfer fluid to the container (3), wherein the condenser unit (8) has an outlet (81) via which a residual gas phase can be discharged, characterized in that - that the fluid line (7) serving as the supply line (71) and return line (72) of the condenser unit (8) is a single pipe with a suitable cross-section or a double pipe connected to the container (3). Cooling system (1) according to claim 1, characterized in that the fluid line (7, 71, 72) has a structured inner surface. Cooling system (1) according to claim 2, characterized in that the structured inner surface of the fluid line (7, 71, 72) is a helically circumferential ribbing. Cooling system (1) according to one of claims 1 to 3, characterized in that the fluid line (7, 71, 72) is a pipeline or double pipeline running at an angle of inclination with respect to the effect of gravity. Cooling system (1) according to claim 4, characterized in that the angle of inclination of the fluid line (7, 71, 72) with respect to the effect of gravity is at least 2°. Cooling system (1) according to one of claims 1 to 5, characterized in that the supply line (71), return line (72) and / or the outlet (81) can be closed or opened individually or in combination with one another by valves (700, 710, 720, 810).Cooling system (1) according to one of claims 1 to 6, characterized in that a collecting container (9) is arranged downstream of the outlet (81), via which the residual gas phase can be discharged. 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). Cooling system (1) according to one of claims 1 to 6, characterized in that a vacuum pump (10) is arranged downstream of the outlet (81), via which vacuum pump the residual gas phase can be discharged. can be discharged. Cooling system (1) according to one of claims 1 to 9, characterized in that the heat exchanger device (6) and the condenser unit (8) have a common supply unit for a single-phase heat transfer medium for cooling. Cooling system (1) according to claim 10, characterized in that the quantity distribution of the single-phase heat transfer medium for cooling for the heat exchanger device (6) and the condenser unit (8) of the common supply unit takes place by means of an active control of the volume flow of the single-phase heat transfer medium. Cooling system (1) according to one of claims 1 to 11, characterized in that at least partially on the fluid line (7) a Cooling device (73) is arranged.

Images