COOLING SYSTEM FOR LIQUID IMMERSION COOLING OF ELECTRONIC COMPONENTS

Description

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

[0002] Liquid immersion cooling systems, such as two-phase immersion cooling systems, are an active cooling solution for electronic components that generate a significant amount of heat during operation. When the components are immersed in a heat transfer fluid, which typically has a relatively low boiling point, the heat generated by the electronic component can evaporate the surrounding liquid heat transfer fluid, thus dissipating heat from the component. A condenser then liquefies the vaporous heat transfer fluid, which is subsequently returned to the reservoir for cooling.

[0003] From US patent 10,512,192 B2, a two-phase immersion cooling system with a cooling tank is known. A condensation chamber, in which the gaseous fluid produced during the cooling process is condensed, is connected to the liquid fluid in the cooling tank. A vapor diversion structure is arranged above the heat-generating electronic components located within the cooling medium in the cooling tank. The evaporated fluid is directed by the vapor diversion structure into the condensation chamber for liquefaction.

[0004] However, when the immersion cooling system is opened to access electronic components or for other system maintenance, some heat transfer fluid is lost as vaporous fluid escapes into the environment. Reducing the amount of lost heat transfer fluid is environmentally friendly and can result in significant cost savings when operating a two-phase immersion cooling system.

[0005] In this context, a cooling system for computer components is known from US patent 10,477,726 B1. Inside a pressure-controlled container, the internal pressure is reduced to as low as 650 hPa. The container holds a thermally conductive, 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 and are at least partially immersed in the liquid phase of the fluid. A condenser condenses the dielectric gas-phase fluid, which evaporates due to the heat generated by the computer components, back into a dielectric liquid-phase fluid. An airlock on the pressure-controlled container allows for the replacement of computer components during operation. Components to be exchanged can be accessed through this airlock using a robotic device.

[0006] Robot arms inside and outside the pressure-controlled container are used to replace components. If an electronic component malfunctions, a removal sequence is initiated. The internal arm removes the component and places it inside the airlock through the inner airlock door. Once this sequence is complete, the inner airlock door closes, the airlock pressure is equalized with the outside atmosphere, and an outer airlock door opens. Once the outer door is open, an external robotic arm system removes the component from the airlock.

[0007] The interior of the airlock can be purged with nitrogen and / or another inert gas before the airlock is opened to the outside environment. This minimizes the loss of dielectric fluid vapor and, in particular, prevents ambient air from entering the vessel. Nevertheless, a gas exchange of the inert gas used in the airlock into the cooling system does occur.

[0008] Documents US 2020093038 A1 and US 2017280587 A1 also disclose immersion cooling systems.

[0009] The invention is based on the objective of further developing a cooling system for liquid immersion cooling of electronic components with regard to reducing the loss of heat transfer fluid.

[0010] The invention is described by the features of claim 1. The further referenced claims relate to advantageous embodiments and further developments of the invention.

[0011] The invention includes a cooling system for liquid immersion cooling of electronic components. The cooling system comprises a container containing liquid heat transfer fluid, into which electronic components can be immersed. The container has a gas space above the surface of the liquid heat transfer fluid. The cooling system also includes a heat exchanger in the gas space of the container for generating liquid heat transfer fluid. The cooling system has a transfer chamber on the container for exchanging electronic components. The transfer chamber has a chamber that is hermetically sealed from the gas space of the container to prevent gas exchange.

[0012] In addition, the cooling system may advantageously include a control device designed to regulate the operation of the fluid circulation, for example as a function of the temperature of the heat transfer fluid and the pressure conditions in the tank and / or in the lock device.

[0013] The invention is based on the premise that the hermetic seal prevents air, water vapor, or inert gas from entering the container holding the cooled electronic components. This ensures that the gaseous heat transfer fluid is not contaminated by foreign gases during the cooling process. This is achieved by a barrier that separates the airlock chamber from the container and prevents any exchange of substances with the gaseous heat transfer fluid. The airlock assembly is completely sealed against any exchange of matter with the container. This is achieved in particular by using liquid heat transfer fluid to seal the airlock against gas penetration. The transition area between the container and the airlock chamber is filled with liquid heat transfer fluid.

[0014] Inside the container, the electronic components are arranged in a bath of heat transfer fluid in a manner suitable for cooling. This fluid evaporates, thus cooling the components. Before and / or during commissioning, the proportion of non-condensable gases can be removed from the system. The heat exchanger of the cooling system can be designed as a bundle of heat exchanger tubes to generate liquid heat transfer fluid in the container's gas space. Multiple tube bundles can also be distributed throughout the container's gas space.

[0015] The airlock system is designed to allow components to be fed through the hermetically sealed airlock, preventing gas exchange, with virtually no pressure difference between the environment and the container. This prevents or significantly reduces the ingress of air and other media into the system, as well as the loss of heat transfer fluid. The airlock system can also be designed to be detachable from the container. For example, the airlock can be a module that can be inserted into and removed from the container and immersed to a certain depth in the liquid heat transfer fluid. A suitable module would be, for instance, a square or rectangular one, which, when ready for use, is immersed in the liquid heat transfer fluid with its lower opening inside the container and whose upper opening can be closed off from the external environment with a cover.

[0016] The lock chamber of the airlock system can also be flooded with heat transfer fluid from the reservoir or a separate storage tank. This is achieved, for example, by increasing the gas pressure in the reservoir to a level that allows the liquid heat transfer fluid to enter the lock chamber according to the principle of communicating vessels, displacing the gas present there. Due to suitable pressure conditions between the external and internal pressures, the lock chamber can also be completely flooded with liquid heat transfer fluid for the exchange of electronic components. After the airlock system is sealed from the outside environment, no outside air or other foreign gases are present in the lock chamber.

[0017] Inside the container, the electronic components are arranged in a bath of heat transfer fluid in a manner suitable for the cooling requirements and are cooled by the evaporation of this fluid. A control unit uses sensors to monitor and control pressure, temperature, conductivity, and all other process-relevant parameters.

[0018] The particular advantage is that the airlock system allows the cooling systems to be optimized in terms of efficiency, loss of heat transfer fluid and moisture ingress into the system.

[0019] In a preferred embodiment of the invention, a partition wall can be arranged for the hermetic sealing of the lock chamber, which is immersed to a depth in the liquid heat transfer fluid. This creates a siphon formed from the liquid heat transfer fluid, which seals the gas space in the container and the gas space of the lock chamber against gas exchange.

[0020] Advantageously, the immersion depth of the partition can be variable. This allows the partition to be at least partially removed when the airlock is closed, facilitating the repositioning of the electronic components into their operating position. This partition can, for example, be moved or removed by a hinged mechanism.

[0021] In an advantageous embodiment of the invention, a loading system can be arranged in the container, enabling the electronic components to be transported from the airlock to the operating position for replacement. A loading system can consist of robot arms or linear drive devices. With a suitable design of the device, component replacement can be carried out via a fully automated loading system. Alternatively, gloves can be positioned at suitable container openings for replacing the electronic components from the airlock to the operating position. This allows for manual access to the interior of the container, similar to the principle of a gas-tight glovebox.

[0022] In an advantageous embodiment of the invention, a storage unit for the temporary storage of electronic components can be provided in the airlock. Equipped with an additional or adjacent storage unit, access to the components to be replaced is easily possible without opening the cooling system.

[0023] Advantageously, an additional heat exchanger can be designed as a lock cooling system, which can separately temperature-control the heat transfer fluid located in the lock chamber. This allows the heat transfer fluid in the lock chamber to be temperature-controlled separately from the entire circuit. As a result, any residual gaseous heat transfer fluid can be converted into the liquid phase. The condensation of the steam can be carried out by an integrated or adjacent condenser. Furthermore, it is advantageous to keep the gas pressure low when the lock chamber is opened by maintaining a cool heat transfer fluid in the lock chamber.

[0024] In an advantageous embodiment, the airlock and / or the container can have a degassing device with which non-condensable gases can be separated from the gaseous heat transfer fluid. In this way, the small amount of gas that enters the cooling system can also be removed from the cooling circuit.

[0025] Advantageously, the airlock system can be purged with a protective gas via a gas connection. Inert gases, in particular, can be used to remove disruptive residual gases, such as ambient air, from the airlock chamber.

[0026] Advantageously, a pressure equalization tank can also be installed on the tank and / or on the lock system. A pressure equalization tank allows for precise regulation of the liquid fluid level in the gas space of the tank and in the lock chamber. Such a system also enables degassing processes to be carried out in the lock chamber, for example, after a lock operation.

[0027] Advantageously, the container can be equipped with an auxiliary heater that assists in the evaporation of the heat transfer fluid. This device can regulate the pressure of the cooling system independently of the operation of the electronic components or the cooling capacity of the heat exchanger.

[0028] In an advantageous embodiment of the invention, the container can be designed as a pressure vessel operating under negative and / or positive pressure. For the transfer of electronic components, it may be necessary to regulate the pressure relative to the ambient air pressure in order to control the level of the liquid fluid in the transfer chamber. This allows the cooling system to be variably adjusted under both positive and negative pressure relative to the ambient atmosphere without negatively affecting or interrupting its operation.

[0029] Exemplary embodiments of the invention are explained in more detail with reference to the schematic drawings.

[0030] It shows: Fig. 1 a schematic oblique view of a cooling system, Fig. 2 a schematic front view of a cooling system with an advantageous embodiment of a sluice device, and Fig. 3 a schematic front view of a cooling system with a further embodiment of a sluice device.

[0031] Corresponding parts are marked with the same reference symbols in all figures.

[0032] Fig. 1 Figure 1 shows a schematic oblique view of a cooling system 1 for liquid immersion cooling of electronic components 2. The cooling system 1 comprises a container 3 and an airlock 8 for exchanging electronic components 2. The liquid dielectric heat transfer fluid 4 located inside the container 3 extends into the airlock chamber 81 of the airlock 8. The liquid heat transfer fluid 42 located in the airlock chamber 81, together with the partition 82, forms a hermetic seal against gas exchange from the gas space 5 of the container 3. For the hermetic seal, the partition 82 is immersed in the liquid heat transfer fluid 4 and thus separates the airlock chamber 81 from the gas space 5 of the container 3 on the gas side.

[0033] In cooling system 1, a Fig. 1 An automated loading system (not shown) is arranged in container 3, which transports the electronic components 2 from the airlock 8 to the operating position 31 for replacement. Robot grippers or linear transport systems can transport the electronic components 2, automatically retrieving them from operating position 31 and, for example, placing them in the storage compartment 9 of the airlock 8. Conversely, ready-to-install electronic components 2 are retrieved from storage compartment 9 by the loading system and transferred to operating position 31. The airlock 8 itself can also be operated externally by automated devices.

[0034] To replace electronic components 2, the cover 83 of the airlock 8 is opened, and a component 2 is placed in the airlock in the storage compartment 9. Defective parts are then transported from there to the outside via the airlock. Before the cover 83 is opened, inert gas, for example, can be introduced into the airlock chamber 81 via a gas connection 11. This gas, along with a portion of the gaseous heat transfer fluid present in the airlock chamber 81, is then at least partially discharged via a degassing device 10. This creates a purging process in the airlock chamber 81, so that when the cover 83 is opened, no or only a very small amount of gaseous heat transfer fluid escapes from the airlock. After the cover 83 is closed, the airlock chamber 81 can be purged of ambient air by another purging process with inert gas.If pressure equalization is required at airlocks relative to atmospheric pressure, a pressure equalization tank 13 can build up the necessary pressure in the gas space 5. Pressure equalization can also be achieved during the airlock process via an auxiliary heater 12 located in the liquid heat transfer fluid 4 in the container 3. During the airlock operation, the auxiliary heater 12 increases the internal pressure in the gas space 5 for the cooling system 1, which otherwise operates under negative pressure, thus establishing the required pressure equalization. The cooling capacity of the heat exchanger 6 is not affected by this. Nevertheless, it can also be used for pressure regulation.

[0035] Fig. 2 Figure 1 shows a schematic front view of a cooling system 1 with an advantageous embodiment of an airlock 8. An airlock cooling unit 7 is arranged in the airlock 8, which liquefies the remaining portion of the gaseous heat transfer fluid and further reduces the temperature of the liquid heat transfer fluid 4 in the airlock chamber 42. This reduces the partial pressure of the heat transfer fluid, particularly in the airlock 8, during the airlock process of electronic components 2. If overpressure builds up in the gas chamber 5, the fluid surface area 43 in the airlock 8 increases. This reduces the gas volume in the airlock chamber 81. When the lid 83 is opened, less gas exchange with the ambient air occurs, or, if the airlock chamber 81 is completely flooded, no gas exchange occurs.

[0036] Fig. 3Figure 1 shows a schematic front view of a cooling system 1 with a further embodiment of an airlock device 8. In this airlock device, the fluid surface 41 in the gas chamber 5 can be at a higher level than the fluid surface 43 in the airlock chamber 8, and vice versa, depending on whether there is a negative or positive pressure in the gas chamber 5 during the cooling process. The outwardly sealing cover 83 now rests directly on the liquid heat transfer fluid 42 in the airlock device 8. After an airlock operation, the cover 83 completely seals the airlock chamber 81 from the outside air. The electronic components 2 can now be replaced directly after opening the cover 83. In this case, the easily accessible storage tank 9 can also be easily loaded or emptied. After the airlock operation, the outside air is immediately displaced by the cover 83.For this purpose, 83 small closable ventilation holes can be arranged in the lid. Reference symbol list

[0037] 1 Cooling system 2 Electronic component 3 Container 31 Operating position 4 Liquid heat transfer fluid 41 Fluid surface in gas space 42 Liquid heat transfer fluid in airlock space 43 Fluid surface in airlock space 5 Gas space 6 Heat exchanger unit 7 Additional heat exchanger unit, airlock cooling 8 Airlock unit 81 Airlock space 82 Partition 83 Cover 9 Storage tank 10 Degassing unit 11 Gas connection 12 Auxiliary heater 13 Pressure equalization tank

Claims

1. Cooling system (1) for liquid immersion cooling of electronic components (2), comprising - a container (3) which contains therein liquid heat transfer fluid (4) in which electronic components (2) can be immersed, wherein the container (3) has a gas compartment (5) over the surface (41) of the liquid heat transfer fluid (4), - a heat exchanger device (6) in the gas compartment (5) of the container (3) for forming liquid heat transfer fluid (4), - wherein the cooling system (1) has on the container (3) a lock device (8) for exchanging electronic components (2), characterized in that the lock device (8) has an airlock chamber (81) which is hermetically sealed against a gas exchange with respect to the gas compartment (5) of the container (3), characterised in that in order to hermetically seal the airlock chamber (81) from the gas compartment (5) there is arranged a partition wall (82) which is introduced with an immersion depth into the liquid heat transfer fluid (4).

2. Cooling system (1) according to claim 1, characterised in that the immersion depth of the partition wall (82) is configured to be variable.

3. Cooling system (1) according to either claim 1 or claim 2, characterised in that there is arranged in the container (3) a supply system by means of which for an exchange the electronic components can be transported from the lock device (8) to the operating position (31).

4. Cooling system (1) according to any one of claims 1 to 3, characterised in that a store (9) for temporary storage of electronic components (2) is provided in the airlock chamber (81).

5. Cooling system (1) according to any one of claims 1 to 4, characterised in that another heat exchanger device (7) is in the form of a lock cooling system which can separately control the temperature of the heat transfer fluid (42) located in the airlock chamber (81).

6. Cooling system (1) according to any one of claims 1 to 5, characterised in that the lock device (8) and / or the container (3) has / have a degassing device (10) by means of which gases which cannot be condensed can be separated from the gaseous heat transfer fluid.

7. Cooling system (1) according to any one of claims 1 to 6, characterised in that the lock device (8) can be flooded with a protective gas via a gas connection (11).

8. Cooling system (1) according to any one of claims 1 to 7, characterised in that a pressure compensation container (13) is additionally arranged on the container (3) and / or on the lock device (8).

9. Cooling system (1) according to any one of claims 1 to 8, characterised in that the container (3) is provided with a supplementary heating unit (12) which acts as a support for evaporation of the heat transfer fluid (4).

10. Cooling system (1) according to any one of claims 1 to 9, characterised in that the container (3) is in the form of a pressure container which functions with a reduced pressure and / or excess pressure.