Cooling system for liquid immersion cooling of electronic components

Abstract

The invention relates to a cooling system (1) 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) for the purpose of forming a liquid heat transfer fluid (4) in a gas space (5) of the container (3),-a first condenser unit (7) arranged outside the container (3), the first condenser unit (7) being connected to the gas space (5) of the container (3) by means of a first supply line (71) for mass transfer of a gaseous medium and having a first return line (72), the first return line (72) being connected to the gas space (5) of the container (3) by means of a second supply line (71) for mass transfer of the gaseous medium. A first condenser unit (7) is provided for conveying the condensed heat transfer fluid to the container (3), a second condenser unit (8) is provided, which is connected to the first condenser unit (7) via a second supply line (81) for the exchange of the gaseous medium, and which has a second return line (82) for conveying the condensed heat transfer fluid to the container (3), and-the second condenser unit (8) has an outlet (83) via which the residual gas phase can be discharged.

Description

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

[0002] Cooling systems for liquid immersion cooling, such as two-phase immersion cooling systems, are active cooling solutions for electronic components that generate a lot of heat during operation. When 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 a reservoir for cooling.

[0003] In publication US 10 512 192 B2 a two-phase immersion cooling system with a cooling tank is disclosed. A condensation chamber is connected to the liquid fluid in the cooling tank, in which the gaseous fluid produced during the cooling process is condensed. A vapor redirection structure is arranged above the heat-generating electronic components inside the cooling medium 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 entirely located in the cooling tank.

[0004] In this context, a cooling system for computer components is disclosed in the publication US 10 477 726 B1. A heat-conducting dielectric heat transfer fluid having a liquid phase and a gas phase with a boiling point below 80°C at atmospheric pressure is located in a controlled pressure container. Computer components at least partially immersed in the liquid phase of the heat transfer fluid are arranged in the container. The dielectric electric phase fluid, which has been evaporated by the heat generated by the computer components, is condensed by a condenser to form a dielectric liquid phase fluid. The internal pressure is reduced to 650 hPa inside the controlled pressure container. The user can influence the temperature at which the dielectric liquid evaporates by controlling the pressure in the container in which the system is running. This enables greater cooling capacity to be achieved. The operation of a computer system in a controlled pressure container at an operating pressure that deviates from the ambient pressure usually requires structural adaptation of the system as a whole.

[0005] A cooling system with a container is disclosed in the public document US 2021 / 0 153 392 A1, which can be filled with a two-phase heat transfer fluid as a coolant, and the electronic components can be immersed in its liquid phase. 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 the external condenser device is configured so that it condenses the vapor phase of the heat transfer fluid and returns it to the container with the electronic components as a liquid coolant. To this end, the system includes return and supply lines, which are connected to both the condenser device and the container to form a heat exchange loop. The system also includes a collection container, which is arranged on the supply line and is configured so that it collects the condensed liquid heat transfer fluid before the coolant is supplied to the container. The accumulator also provides backup cooling capacity for the cooling system.

[0006] A cooling system for immersion cooling of electronic components is disclosed in the publication EP 3 453 235 B1, the cooling system having a pressure-sealed tank, the tank being configured to capture in liquid form, wherein the electronic device is immersed in a heat transfer fluid. In addition, there is a vapor space above the surface of the liquid heat transfer fluid. The condenser is arranged outside the pressure-sealed tank, wherein the condenser has an inlet connected to the vapor space by a riser, and is configured to receive heat transfer fluid vapor. In addition, the condenser has a vapor outlet for residual gas that can be tightly closed, and a condensate outlet with a condensate return line to the tank. The condensate return line is configured so that the heat transfer fluid condensed thereby can flow back to the tank from the condensate outlet. Additional condenser tubes may also already exist in the tank for liquefying gaseous heat transfer fluid.

[0007] The object of the invention is to 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 described 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 which can be filled with a two-phase heat transfer fluid inside, in whose liquid phase the electronic components can be immersed. 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 first condenser unit arranged outside the container, wherein the first condenser unit is connected to the gas space of the container by a first supply line for mass transfer of the gaseous medium, and the first condenser unit has a first return line for the condensed heat transfer fluid to the container. According to the present invention, a second condenser unit is arranged, which is connected to the first condenser unit by a second supply line for exchange of the gaseous medium, and the second condenser unit has a second return line for the condensed heat transfer fluid to the container. The second condenser unit has an outlet, and the residual gas phase can be discharged via the outlet.

[0010] The container can be designed to be pressure-tight. Advantageously, the container can be designed as a pressure vessel that can operate under negative pressure and / or positive pressure. By controlling the pressure in the container in which the cooling system operates, a greater cooling capacity can be achieved.

[0011] The heat exchanger device in the gas space preferably consists of at least one tube bundle of 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 end tube bases. The arrangement of these tube bundles or these heat exchanger tubes in the container can be implemented symmetrically and also asymmetrically or along an inclination relative to the container wall.

[0012] The heat exchanger tubes are preferably finned tubes, which are produced from smooth tubes that have been subjected to a forming process. They are particularly suitable as components in efficient, compact and exceptionally 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 material options (including copper, copper alloys, steel, titanium or titanium alloys) ensures that materials suitable for different needs are available for the corresponding requirements, in particular with respect to durability and deformability.

[0013] The two-phase heat transfer fluid (also denoted coolant) represents the external fluid located in the container, in whose liquid component the electronic components are immersed. The internal fluid located in the heat exchanger tubes is usually a single-phase heat transfer medium, such as process water, glycol or thermal oil. However, it is also possible to use a two-phase medium in conjunction with a cooling circuit.

[0014] In the container, the electronic components are arranged in a manner suitable for cooling in a bath of a liquid heat transfer fluid and are cooled by evaporation of the liquid fluid. Before and / or during start-up, a proportion of non-condensable gases can be effectively removed from the system.

[0015] In an embodiment according to the invention, computer components and immersion cooling as well as associated power supplies, network connections, wired connections, etc. may be arranged in a container having an internal pressure that deviates from ambient pressure during operation.

[0016] In this context, it is also advantageous to combine power, water, vacuum and network connections in a pipe bundle in order to minimize access holes into the container and to reduce the risk of leaks, especially when the system is under vacuum or positive pressure in operation.

[0017] In an advantageous embodiment, during operation, the vessel is maintained at up to 200 hPa below atmospheric ambient pressure, which 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 several specific embodiments, the controlled pressure vessel can have an even lower pressure of up to 500 hPa below ambient pressure.

[0018] Embodiments of cooling system according to the present invention include containers designed to use two-phase liquid to immerse cooling system.Container includes the groove composed of dielectric cooling fluid, heat exchanger device and other external condenser units connected in series for condensing dielectric fluid from gas phase into liquid.The first condenser unit located outside the container is intended to initially condense the gaseous heat transfer fluid into the ratio of the largest possible liquid heat transfer fluid, and the gaseous heat transfer fluid also includes a certain proportion of air and water vapor.The residual gas phase enters the second condenser unit from the first condenser unit through the second supply line.Here, the remaining heat transfer fluid is almost completely condensed from the gas phase, so that basically only air and water vapor remain as the residual gas phase.The target when separating the liquid heat transfer fluid is to keep water vapor in the gas phase by the suitable cooling capacity of the system.This residual gas mixture is discharged from the cooling system via the outlet of the second condenser unit.

[0019] In addition, devices for holding computer components and for distributing power from the power supply system to devices and components located inside the container can also be arranged. It goes without saying that a plurality of specialized connections are used in order to operate a computer system maintained in a container, for example, under negative pressure. Several embodiments of the system according to the present invention can use a series of fiber optic interfaces that enable connectivity in the container and distribute optical fibers to different holding devices for electronic components. Several embodiments of the container may include sensors for safe operation. These sensors may include temperature sensors, liquid level sensors, pressure sensors, position sensors, electrical sensors and / or cameras in order to ensure and automate the operation of the system.

[0020] These systems may include, for example, a pressure sensor within the controlled pressure vessel that monitors the pressure to ensure that there is no significant leak. A gas sensor may also be arranged on the outer surface of the controlled pressure vessel and detect the presence of possible dielectric vapor escaping from the controlled pressure vessel.

[0021] Furthermore, the cooling system can advantageously have a control device which is designed to control 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.

[0022] An advantageous embodiment of the cooling system according to the invention may be an external frame which stabilizes the container and which may be designed from metal profiles in the form of a frame structure and which surrounds and supports the container. The frame structure may be an open design comprising covers, side walls and doors for easy access during operation and for maintenance operations. This allows access to the cooling system at the on-site location.

[0023] In an advantageous embodiment, a mounting system can be set up by which the electronic component can be transported from the locking device to the operating position for its replacement. The mounting system can consist of a robot arm or a linear drive. By a suitable configuration of the device, the replacement of the component can be carried out via a fully automatic mounting system. Alternatively, gloves can also be arranged at a suitable container opening in order to replace the electronic component from the locking device to the operating position. This enables installation by manual access to the interior of the container.

[0024] In a preferred embodiment of the present invention, the supply line, return line and / or outlet can be closed or opened individually or in combination with each other by valves. In order to implement the method in an appropriate manner, a separate valve is opened as required to transport a gaseous medium or a liquid heat transfer fluid. The supply or discharge can occur cyclically or even in a continuous mode. In particular, the valve circuit at the outlet is suitable for leaving the cooling system with as little heat transfer fluid as possible or even without heat transfer fluid.

[0025] Advantageously, the second condenser unit can be heatable. This operating mode allows a short heating of the residual gas phase consisting of water vapor and air for pressure compensation. In this operating mode, the condensed heat transfer fluid is located in the second return line. The liquid heat transfer fluid can be returned to the container by a certain positive pressure or by gravity. The residual gas can also be discharged more easily by means of this heating and the pressure compensation relative to the ambient air or positive pressure associated therewith. By a certain positive pressure relative to the environment, no external air can enter the cooling system via the outlet in the opposite direction.

[0026] In an advantageous embodiment of the invention, a collecting container can be arranged downstream of the outlet, from which the residual gas phase can be discharged. This container also ensures that no air can enter the cooling system from the environment. The container can be an expandable elastic bladder or a bellows with a variable volume.

[0027] Advantageously, a drying unit for separating the water vapor from the gas phase can be arranged between the outlet and the collecting container. For example, when the load changes, the pressure level in the entire cooling system changes. If necessary, external air or residual gas can be introduced into the cooling system via the collecting container via the drying unit for pressure compensation. The water vapor is chemically bonded by the drying unit. Silica gel is suitable for such a drying unit. Other advantageous locations for the drying unit can also be located in the first and / or second condenser, including its supply line or return line.

[0028] In an advantageous embodiment of the invention, a vacuum pump can be arranged downstream of the outlet, from which the residual gas phase can be discharged. In this case, the residual gas phase consisting of water vapor and air at the outlet can also have a negative pressure relative to the environment, since the flow direction of the residual gas to the outside is always ensured via the vacuum pump.

[0029] Advantageously, the first condenser unit may have a greater cooling capacity than the second condenser unit. For example, the cooling capacity of the first condenser unit is at least three times, and further preferably at least five times, greater than the cooling capacity of the second condenser unit. Thus, the largest proportion of the heat transfer fluid has been separated in the first condenser unit, and the air-water vapor component transported to the second condenser unit is rich in the gas phase.

[0030] Advantageously, the heat exchanger arrangement and the first condenser unit may have a common first supply unit of the first single-phase heat transfer medium for cooling. Thus, both units are at a uniform temperature level suitable for the separation process of the heat exchanger fluid.

[0031] Advantageously, the second condenser unit can have a second supply unit for a second single-phase heat transfer medium for cooling. Thus, independent, different temperature levels can be set in the second condenser unit to further effectively separate the individual phase components.

[0032] In an advantageous embodiment of the invention, the second condenser unit can be designed so that it can operate at a lower temperature of the single-phase heat transfer medium relative to the first condenser unit for cooling. Specifically, it must be taken into account to select pressure and temperature conditions that are not lower than the dew point of the water component in order to remain in the residual gas phase and enable it to dissipate. In this pressure-temperature range, the second condenser unit can be optimally used.

[0033] By following Figure 1, an exemplary embodiment of the present invention is explained in more detail.

[0034] Figure 1 A schematic diagram of a cooling system 1 for liquid immersion cooling of electronic components 2 is shown. The cooling system 1 comprises a container 3 which can be filled with a two-phase heat transfer fluid inside. The two-phase heat transfer fluid represents an external fluid located in the container 3, having a liquid heat transfer fluid component 4 in which the electronic components 2 are immersed, and a gas space 5 having a gaseous heat transfer fluid component. In the container 3, a heat exchanger device 6 is arranged in the gas space 5 of the container 3 for forming the liquid heat transfer fluid 4.

[0035] In this advantageous embodiment, the heat exchanger device 6 in the gas space 5 consists of tube bundles 61 which in each case have a plurality of heat exchanger tubes arranged parallel to one another.

[0036] In this figure and in the embodiment shown, the container is slightly tapered in the area of ​​the liquid heat transfer fluid 4 by a container wall that protrudes inwards and is open outwards only in the gas space. The shape of the container 3 is supported by a metal profile frame 31. The container 3 is thus already surrounded by a stable outer frame.

[0037] The first condenser unit 7 is arranged outside and above the container 3. The first condenser unit 7 is connected to the gas space 5 of the container 3 via a first supply line 71 for mass transfer of the gaseous medium. A first return line 72 for liquefied heat transfer fluid to the container 3 is also provided, through which the liquid heat transfer fluid is returned from the first condenser unit 7 to the container 3 under gravity drive. In order to control the mass transfer, a valve 710 is installed in the first supply line 71, and a valve 720 is installed in the first return line 72. Therefore, a gaseous mixture of heat transfer fluid, air and water vapor is cyclically or continuously discharged from the container 3 via the valve 710 of the first supply line 71. Only the liquid heat transfer fluid is returned to the container 3 via the valve 720 of the first return line 72.

[0038] The gaseous mixture of substances remaining in the first condenser unit 7 is fed to the second condenser unit 8, which is connected to the first condenser unit 7 via a second feed line 81. A valve 810 installed in the second feed line also controls the gas flow. A second return line 82 for the heat transfer fluid for further condensation leads directly from the second condenser unit 8 to the container 3. The return of the condensate formed in the second condenser unit 8 is further controlled by a valve 820 installed in the second return line 82. After the heat transfer fluid has been almost completely condensed, the remaining residual gas phase consisting only of air and water vapor is discharged to the outside via an outlet 83 through an outlet valve 830. In order to additionally separate the water vapor, a drying unit 11 for separating water vapor from the gas phase is provided between the outlet 83 and the collecting container 9.

[0039] Depending on the pressure level, the residual gas phase can be discharged directly to the environment. This can be done by a heating device in the second condenser unit 8, which sets the pressure level according to the environment through appropriately controlled valves.

[0040] Alternatively, however, the residual gas phase can also be discharged via the vacuum pump 10. For this purpose, the outlet 83 is connected via a feed line 101 to the vacuum pump 10, which controls the residual gas flow to the outside via a valve controller 1010 through a discharge line 102 of the vacuum pump 10.

[0041] Alternatively or additionally, the residual gas phase can also be conducted to the collecting container 9 via a supply line 91 with a valve 910, which can be designed as a bellows of an expandable volume for generating negative pressure. 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.

[0042] List of Reference Numerals

[0043] 1 Cooling system

[0044] 2 Electronic components

[0045] 3 Container

[0046] 31 Metal profile frame

[0047] 4 Liquid heat transfer fluid

[0048] 41 Surface of liquid fluid in container

[0049] 5 Gas heat transfer fluid, gas space

[0050] 6 Heat exchanger device

[0051] 61 Discipline

[0052] 7. First condenser unit

[0053] 71 First supply line

[0054] 710 Valve of the first supply line

[0055] 72 First return line

[0056] 720 Valve for first return line

[0057] 8 Second condenser unit

[0058] 81 Second supply line

[0059] 810 Valve for the second supply line

[0060] 82 Second return line

[0061] 820 Valve for the second return line

[0062] 83 Exit

[0063] 830 Outlet valve

[0064] 9 Collection container, bellows

[0065] 91 Supply line - collection container

[0066] 910 Supply line valve - collecting container

[0067] 92 Discharge line - collection container

[0068] 920 Valve for discharge line - collecting container

[0069] 10 Vacuum pump

[0070] 101 Supply line - vacuum pump

[0071] 1010 Valve for supply line - vacuum pump

[0072] 102 Discharge line - vacuum pump

[0073] 11 Drying unit

Claims

1. A cooling system (1) for liquid immersion cooling of electronic components (2), comprising: - a container (3) which can be filled internally with a two-phase heat transfer fluid (4), in the liquid phase of which the electronic component (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 the purpose of forming a liquid heat transfer fluid (4), - a first condenser unit (7) arranged outside the container (3), wherein the first condenser unit (7) is connected to the gas space (5) of the container (3) via a first supply line (71) for mass transfer of the gaseous medium, and the first condenser unit has a first return line (72) for conveying condensed heat transfer fluid to the container (3), It is characterized in that - arranging a second condenser unit (8) which is connected to the first condenser unit (7) via a second supply line (81) for exchanging the gaseous medium and which has a second return line (82) for conveying the condensed heat transfer fluid to the container (3), The second condenser unit (8) has an outlet (83) through which the residual gas phase can be discharged.

2. The cooling system (1) according to claim 1, characterized in that The supply line (71, 81), the return line (72, 82) and / or the outlet (83) can be closed or opened by means of valves (710, 810, 720, 820, 830) individually or in combination with one another.

3. The cooling system (1) according to claim 1 or 2, characterized in that: The second condenser unit (8) is heatable.

4. Cooling system (1) according to one of claims 1 to 3, characterized in that A collecting container (9) is arranged downstream of the outlet (83), from which the residual gas phase can be discharged.

5. The cooling system (1) according to claim 4, characterized in that A drying unit (11) for separating water vapor from the gas phase is arranged between the outlet (83) and the collecting container (9).

6. Cooling system (1) according to one of claims 1 to 3, characterized in that A vacuum pump ( 10 ) is arranged downstream of the outlet ( 83 ), from which the residual gas phase can be discharged.

7. Cooling system (1) according to one of claims 1 to 6, characterized in that The first condenser unit (7) has a greater cooling capacity than the second condenser unit (8).

8. Cooling system (1) according to one of claims 1 to 7, characterized in that The heat exchanger device (6) and the first condenser unit (7) have a common first supply of a first single-phase heat transfer medium for cooling.

9. The cooling system (1) according to claim 8, characterized in that The second condenser unit (8) has a second supply unit for a second single-phase heat transfer medium for cooling.

10. The cooling system (1) according to claim 9, characterized in that The second condenser unit (8) is designed such that it can operate at a lower temperature of the single-phase heat transfer medium used for cooling than the first condenser unit (7).

Images