Cooling system for liquid immersion cooling of electronic components

Abstract

The present invention relates to a cooling system (1) for liquid immersion cooling of an electronic component (2), comprising a container (3) which can be filled inside with a two-phase heat transfer fluid (4) for immersing the electronic component (2) in a liquid phase. The container (3) has a gas chamber (5) above the surface (41) of the liquid heat transfer fluid (4). To form the liquid heat transfer fluid (4), a heat exchanger (6) is provided in the gas chamber (5) of the container (3). The cooling system (1) comprises a first condensing device unit (7) arranged outside the container (3). The first condensing device unit (7) is connected to the gas chamber (5) of the container (3) by a first supply line (71) for exchanging a gaseous medium, and has a first return line (72) for the condensed heat transfer fluid to the container (3). A second condensing device unit (8) is arranged. The second condensing device unit (8) is connected to the first condensing device unit (7) via a second supply line (81) for exchanging a gaseous medium, and has a second return line (82) for the condensed heat transfer fluid to the container (3). The second condensing device unit (8) is characterized by having an outlet (83) through which a residual gas phase can be discharged.

Description

Technical Field

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

Background Art

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

[0003] From Patent Document 1, a two-phase immersion cooling system having a cooling tank is known. A condensation chamber that condenses the gaseous fluid generated during the cooling process is connected to the liquid fluid in the cooling tank. Here, the heat-generating electronic components are in the cooling medium in the cooling tank, and a vapor bypass structure is arranged above them. The vaporized fluid is sent to the condensation chamber for liquefaction using the vapor bypass structure. The condensation chamber is completely inside the cooling tank.

[0004] In this regard, from Patent Document 2, a cooling system for computer components is known. Inside a pressure-controlled container, a heat-transfer dielectric heat-transfer fluid having a boiling point below 80 °C at atmospheric pressure exists in a liquid phase and a gas phase state. Inside the container, computer components are arranged that are at least partially immersed in the liquid phase of the heat-transfer fluid. By means of a condensation device, the dielectric gas-phase fluid vaporized by the heat generated from the computer components is condensed into a dielectric liquid-phase fluid. Inside the pressure-controlled container, the internal pressure is reduced to 650 hPa. By controlling the pressure inside the container in which the system is operating, the user can influence the temperature at which the dielectric liquid vaporizes. Thereby, an improvement in cooling performance can be achieved. In order to operate the computer system inside the pressure-controlled container at an operating pressure different from the ambient pressure, in most cases, it is necessary to adapt the overall structural design of the system.

[0005] From Patent Document 3, a cooling system is known that comprises a container that can be filled with a two-phase heat-transfer fluid as a coolant and in which electronic components can be immersed in its liquid phase. This container has a gas chamber above the surface of the liquid heat-transfer fluid. Above this container, a separate external condensation device is arranged, which is configured to condense the vapor phase of the heat-transfer fluid and return it as a liquid coolant into the container containing the electronic components. For this purpose, the system comprises a return line and a supply line, which are connected to both the condensation device and the container, thereby forming a heat exchange loop. Furthermore, this system also comprises a collection container arranged in the supply line and designed to collect the condensed liquid heat-transfer fluid before the coolant is sent to the container. This storage device also provides a pre-cooling capacity for the cooling system.

[0006] A cooling system for liquid immersion cooling of electronic components is known from Patent Document 4, which includes a pressure-resistant tank configured to hold a liquid heat transfer fluid, in which electronic devices are immersed. Further, there is a vapor chamber above the surface of the liquid heat transfer fluid. Outside the pressure-resistant tank, a condenser is arranged, which is connected to the vapor chamber via a vertical tube and has an inlet configured to store the heat transfer fluid. Further, this condenser has a sealable vapor outlet for residual gas and a condensate outlet with a condensate return line to the tank. The condensate return line is configured such that the condensed heat transfer fluid can return from the condensate outlet to the tank through it. Additional condenser tubes for liquefying the gaseous heat transfer fluid may already be installed inside the tank.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

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

[0010] The present invention includes a cooling system for liquid immersion cooling of electronic components. This cooling system comprises a container that can be filled with a two-phase heat transfer fluid therein, and the electronic components can be immersed in the liquid phase thereof. The container has a gas chamber above the surface of the liquid heat transfer fluid. Further, the cooling system comprises a heat exchanger in the gas chamber of the container for forming the liquid heat transfer fluid. Furthermore, this cooling system comprises a first condenser unit arranged outside the container, and this first condenser unit is connected to the gas chamber of the container by a first supply line for mass-exchanging a gaseous medium and has a first return line for the condensed heat transfer fluid to the container. Based on the present invention, a second condenser unit is arranged, and this second condenser unit is connected to the first condenser unit for exchanging a gaseous medium via a second supply line and has a second return line for the condensed heat transfer fluid to the container. The second condenser unit has an outlet through which the residual gas phase can be discharged.

[0011] The container can be implemented in a form with excellent pressure resistance. Advantageously, the container may be implemented as a pressure vessel that can operate at negative pressure and / or positive pressure. By controlling the pressure inside the container in which the cooling system operates, an improvement in the cooling capacity can be achieved.

[0012] Preferably, the heat exchanger in the gas chamber consists of at least one tube bundle of a number of heat exchange tubes arranged with respect to each other. The tube bundle can have a number of heat exchange tubes arranged parallel to each other with two end tube sheets. The tube bundle or the heat exchange tubes in the container can be arranged symmetrically with respect to the container wall, and also asymmetrically, or along an inclination.

[0013] Preferably, the heat exchanger tubes are finned tubes manufactured from smooth tubes through a forming process. Finned tubes are particularly suitable as components in heat exchangers that are highly efficient, compact, and extremely stable, 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, allows for a variety of requirements, particularly in terms of durability and deformability, to be met with the right material for each requirement.

[0014] The two-phase heat transfer fluid, also called refrigerant, is the external fluid in the container, in whose liquid part the electronic components are immersed. The internal fluid present in the heat exchanger tubes is usually a single-phase heat transfer medium, such as process water, glycol, or thermal oil. However, two-phase media can also be used here in combination with a cooling circuit.

[0015] Within the vessel, the electrical components are placed in a bath of a liquid heat transfer fluid in a manner suitable for cooling, and the liquid fluid evaporates to cool the electrical components, whereby a portion of the non-condensable gas can be efficiently removed from the system before and / or during start-up.

[0016] In embodiments according to the present invention, computer components and immersion cooling devices, as well as associated power supplies, network connections, wiring connections, etc., can be placed within a container that, during operation, has an internal pressure that is different from the ambient pressure.

[0017] In this regard, it is also advantageous to combine the wiring for the electrical connections, water connections, negative pressure connections and network connections into one bundle to minimize feed-through into the container and reduce the risk of leakage, especially when the system is under negative or positive pressure during operation.

[0018] In advantageous embodiments, the vessel is maintained at a pressure up to 200 hPa below ambient atmospheric pressure during operation, which contributes to lowering the boiling point of the two-phase heat transfer fluid and thereby reducing the operating temperature of computer chips and other components. In some particular embodiments, the pressure-controlled vessel can further have a pressure up to 500 hPa below ambient pressure.

[0019] An embodiment of a cooling system according to the present invention includes a vessel designed for use with a two-phase liquid immersion cooling system. The vessel includes a vessel consisting of a dielectric cooling fluid, a heat exchanger, and an external condenser unit connected in series to condense the dielectric fluid from its gas phase to a liquid. The first condenser unit, located outside the vessel, initially condenses as much of the gaseous heat transfer fluid, including a proportion of air and water vapor, into the liquid heat transfer fluid as possible. The residual gas phase from the first condenser unit reaches the second condenser unit via a second supply line. Here, the remaining heat transfer fluid is almost completely condensed from the gas phase, leaving primarily air and water vapor as the residual gas phase. In this case, the purpose of separating the liquid heat transfer fluid is to retain the water vapor in the gas phase, ensuring adequate cooling performance of the system. This residual gas mixture is discharged from the cooling system through the outlet of the second condenser unit.

[0020] Furthermore, it is also possible to arrange a device for holding computer components and a device for distributing electricity from a power supply system to the devices and components within the container. For example, it goes without saying that a number of special connections are used to operate a computer system inside a container maintained at a negative pressure. In some embodiments of the system according to the present invention, by using a series of optical fiber interfaces, connectivity within the container can be enabled and fibers can be distributed to various holding devices for electronic components. In some embodiments of the container, sensors can be included for safe operation. These sensors can include temperature sensors, fluid level sensors, pressure sensors, position sensors, electrical sensors, and / or cameras in order to ensure and automate the operation of the system.

[0021] These systems can, for example, be provided with a pressure sensor for monitoring pressure inside a pressure-controlled container, ensuring a state without significant leakage. Similarly, a gas sensor is arranged outside the pressure-controlled container to detect the presence of dielectric vapor that may leak from the pressure-controlled container.

[0022] In addition, advantageously, the cooling system can also have a control device, which is provided to control the operation of fluid circulation, for example as a function of the temperature of a two-phase heat transfer fluid, and also to control the pressure ratio within the container.

[0023] An advantageous embodiment of the cooling system according to the present invention can be an outer frame for stabilizing the container, which can be designed from metal profiles in the form of a frame structure and surrounds and supports the container. The frame structure can have an open design with a cover, side walls, and a door for easy access during operation and maintenance work. This enables access to the cooling system at a local site.

[0024] In an advantageous embodiment, a pick-and-place system can be installed that can transfer the electronic component from the locking device to the operating position for replacement. This pick-and-place system may consist of a robotic arm or a linear drive. If this device is appropriately formed, component replacement can be performed by a fully automatic pick-and-place system. Alternatively, gloves can also be placed in a suitable container opening to replace the electronic component from the locking device to the operating position. This enables placement by manually accessing the inside of the container.

[0025] In a preferred embodiment of the present invention, the supply line, return line and / or outlet may be closable or openable individually or in combination with each other via valves. To allow the process to proceed appropriately, the individual valves are opened as necessary so that the gaseous medium or liquid heat transfer fluid is sent further. Supply or discharge can also be carried out in a periodic or continuous mode. In particular, the switching of the valve at the outlet is adjusted so that the outflow of the heat transfer fluid from the cooling system is minimized or eliminated.

[0026] Advantageously, the second condenser unit may be heatable. In this operating mode, it becomes possible to heat the residual gas phase consisting of water vapor and air for a short time to equalize the pressure. In this operating mode, the condensed heat transfer fluid is in the second return line. Due to a certain positive pressure or gravity, the liquid heat transfer fluid can return to the container. By heating and the associated pressure equalization with respect to the ambient air or positive pressure, the residual gas can be easily discharged. When there is a certain positive pressure compared to the surroundings, outside air does not enter the cooling system in the reverse direction through the outlet.

[0027] In an advantageous embodiment of the invention, a collection container can be arranged downstream of the outlet, and the residual gas phase can be discharged via this collection container. This container is also used to prevent air from entering the cooling system from the surroundings. The container can be an expandable elastic balloon or a bellows with a variable volume.

[0028] Advantageously, a drying unit can be arranged between the outlet and the collection container to separate water vapor from the gas phase. For example, when the load changes, the pressure state of the entire cooling system changes. If necessary, the collection container can be used to feed outside air or residual gas into the cooling system via the drying unit to equalize the pressure. Next, the water vapor is chemically reacted by the drying unit. Silica gel is suitable for this type of drying unit. A more advantageous position of the drying unit can be in the first and / or second condenser, including its supply line or return line.

[0029] In an advantageous embodiment of the invention, a vacuum pump can be arranged downstream of the outlet, and the residual gas phase can be discharged via this vacuum pump. In this case, since the flow direction of the residual gas always directed outward is ensured by the vacuum pump, the residual gas phase consisting of water vapor and air at the outlet can have a negative pressure with respect to the surroundings.

[0030] Advantageously, the first condenser unit can have a higher cooling performance than the second condenser unit. For example, the cooling performance of the first condenser unit can be at least 3 times, and more preferably at least 5 times, the cooling performance of the second condenser unit. Therefore, most of the heat transfer fluid is already separated in the first condenser unit, and the air / water vapor component sent to the second condenser unit becomes rich in the gas phase.

[0031] Advantageously, the heat exchanger and the first condenser unit can have a common first supply unit for the first single-phase heat medium for cooling. Therefore, the two units are at a uniform temperature level suitable for the separation process of the heat exchange fluid.

[0032] Advantageously, the second condenser unit can have a second supply unit for the second single-phase heat medium for cooling. Thus, in the second condenser unit, it is possible to set different separation temperature levels in order to more effectively separate the individual phase components.

[0033] In an advantageous embodiment of the invention, for cooling, the second condenser unit can be designed to operate at a lower temperature of the single-phase heat medium than the first condenser unit. In this case, in particular, pressure and temperature conditions that do not fall below the dew point of the moisture are considered, thereby retaining water vapor in the residual gas phase and enabling it to be discharged. In this pressure and temperature range, the second condenser unit can be optimally used.

[0034] Embodiments of the present invention will be described in more detail based on the schematic diagram of FIG. 1.

Brief Description of the Drawings

[0035] [Figure 1] It is a schematic diagram of a cooling system 1 for liquid immersion cooling of an electronic component 2.

Modes for Carrying Out the Invention

[0036] FIG. 1 is a schematic diagram of a cooling system 1 for liquid immersion cooling of an electronic component 2. The cooling system 1 includes a container 3, and a two-phase heat transfer fluid can be filled therein. The two-phase heat transfer fluid is an external fluid in the container 3, and has a liquid heat transfer fluid portion 4 in which the electronic component 2 is immersed and a gas chamber 5 having a gaseous heat transfer fluid portion. In the container 3, a heat exchanger 6 is disposed in the gas chamber 5 of the container 3 to form the liquid heat transfer fluid 4.

[0037] In this advantageous embodiment, the heat exchanger 6 in the gas chamber 5 consists of a tube bundle 61, and each tube bundle 61 has a plurality of heat exchange tubes arranged parallel to each other.

[0038] In the embodiment shown in the figure, the container 3 has a container wall that protrudes inward and finally opens in the gas chamber 5, so that the region of the liquid heat transfer fluid 4 is slightly narrowed. The shape of the container 3 is supported by a metal profile frame 31. Therefore, the container 3 is already surrounded by a stable outer frame.

[0039] The first condensation device unit 7 is arranged outside the container 3 and above this container 3. The first condensation device unit 7 is connected to the gas chamber 5 of the container 3 by a first supply line 71 for mass-exchanging a gaseous medium. Similarly, a first return line 72 for the liquefied heat transfer fluid to the container 3 is also arranged, through which the gravity-driven liquid heat transfer fluid reaches the container 3 again from the first condensation device unit 7. To control the mass exchange, a valve 710 is attached to the first supply line 71, and a valve 720 is attached to the first return line 72. Therefore, through the valve 710 of the first supply line 71, a gaseous mixture composed of a heat transfer fluid, air, and water vapor is periodically or continuously withdrawn from the container 3. Only the liquid heat transfer fluid is returned into the container 3 through the valve 720 of the first return line 72.

[0040] The gaseous mixture remaining in the first condensation device unit 7 is supplied to the second condensation device unit 8, and this second condensation device unit 8 is connected to the first condensation device unit 7 by a second supply line 81. Here too, a valve 810 attached to the second supply line controls the gas flow. A second return line 82 for the further condensed heat transfer fluid is directly connected from the second condensation device unit 8 to the container 3. The reflux of the condensed water formed in the second condensation device unit 8 is controlled by a valve 820 attached to the second return line 82. The remaining residual gas phase consisting only of air and water vapor after the heat transfer fluid is almost completely condensed is discharged to the outside by an outlet valve 830 through an outlet 83. To additionally separate water vapor, a drying unit 11 for separating water vapor from the gas phase is arranged between the outlet 83 and the collection container 9.

[0041] Depending on the pressure state, the residual gas phase can be directly discharged to the surroundings. This can be done by the heating device in the second condenser unit 8, and this heating device adjusts the pressure state with respect to the surroundings when the valve is appropriately controlled.

[0042] However, alternatively, the residual gas phase can also be discharged by the vacuum pump 10. For this purpose, the outlet 83 is connected to the vacuum pump 10 via the supply line 101, and this vacuum pump 10 controls the external residual gas flow by the valve control 1010 using the discharge line 102 of the vacuum pump 10.

[0043] Alternatively or additionally, the residual gas phase can also be sent to the collection container 9 via the supply line 91 having the valve 910, and this collection container 9 may be designed as a bellows with an expandable volume to generate a negative pressure. When the valve 910 to the collection container 9 is closed during operation, the residual gas can be discharged via the discharge line 92 of the collection container 9 when the valve 920 is open.

Explanation of Signs

[0044] 1 Cooling system 2 Electronic component 3 Container 31 Metal profile frame 4 Liquid heat transfer fluid 41 Liquid fluid surface in the container 5 Gaseous heat transfer fluid, gas chamber 6 Heat exchanger 61 Tube bundle 7 First condenser unit 71 First supply line 710 Valve of the first supply line 72 First return line 720 Valve of the first return line 8 Second condenser unit 81 Second supply line Valve of the second supply line 810 Second return line 82 Valve of the second return line 820 Outlet 83 Outlet valve 830 Collection container, bellows Supply line of the collection container 91 Valve of the supply line of the collection container 910 Discharge line of the collection container 92 Valve of the discharge line of the collection container 920 Vacuum pump 10 Supply line of the vacuum pump 101 Valve of the supply line of the vacuum pump 1010 Discharge line of the vacuum pump 102 Drying unit 11

Claims

1. A cooling system (1) for liquid immersion cooling of an electronic component (2), comprising: - A container (3), inside which a two-phase heat transfer fluid (4) capable of immersing the electronic component (2) in a liquid phase can be filled. The container (3) has a gas chamber (5) above the surface (41) of the liquid heat transfer fluid (4). - A heat exchanger (6) is provided in the gas chamber (5) of the container (3) to form the liquid heat transfer fluid (4). - A first condensation device unit (7) disposed outside the container (3). The first condensation device unit (7) is connected to the gas chamber (5) of the container (3) by a first supply line (71) for exchanging a gaseous medium, and has a first return line (72) for the condensed heat transfer fluid to the container (3). In the cooling system (1), - A second condensation device unit (8) is arranged. The second condensation device unit (8) is connected to the first condensation device unit (7) via a second supply line (81) for exchanging a gaseous medium, and has a second return line (82) for the condensed heat transfer fluid to the container (3). - The second condensation device unit (8) has an outlet (83) through which the residual gas phase can be discharged. The cooling system (1) is characterized by the above.

2. The cooling system (1) according to claim 1, characterized in that the supply lines (71, 78), the return lines (72, 82) and / or the outlet (83) can be individually or in combination closed or opened via valves (710, 810, 720, 820, 830).

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

4. The cooling system (1) according to any one of claims 1 to 3, characterized in that a collection container (9) is arranged downstream of the outlet (83), and the residual gas phase can be discharged through the collection container (9).

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

6. The cooling system (1) according to any one of claims 1 to 3, characterized in that a vacuum pump (10) is arranged downstream of the outlet (83), and the residual gas phase can be discharged through the vacuum pump (10).

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

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

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

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