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) having a container wall (31), inside which a two-phase heat transfer fluid (4) capable of immersing the electronic component (2) can be filled, the container (3) having a gas chamber (5) above the surface (41) of the liquid heat transfer fluid (4), and a heat exchanger (6) being provided in the gas chamber (5) of the container (3) to form the liquid heat transfer fluid (4). This cooling system (1) is characterized in that the heat exchanger (6) in the gas chamber (5) consists of at least one tube bundle (7) of a number of heat exchange tubes (71) arranged relative to one another, the heat exchange tubes (71) being fixed to at least one tube sheet (72), and at least one tube sheet (72) of the tube bundle (7) being formed as part of the container wall (31).

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 immersed mainly 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 the 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. Only the supply and discharge lines of the fluid in the cooling pipe penetrate the cooling tank wall.

[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, a computer component is disposed that is 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 component 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 realized. 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.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] 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.

Means for Solving the Problems

[0007] The present invention is described by the features of claim 1. The other related claims are advantageous embodiments and developments of the present invention.

[0008] The present invention includes a cooling system for liquid immersion cooling of electronic components. The cooling system comprises a container having a container wall, the container being fillable with a two-phase heat transfer fluid, 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 to form the liquid heat transfer fluid. The heat exchanger in the gas chamber consists of at least one tube bundle of a number of heat exchange tubes arranged with each other, and the heat exchange tubes are fixed to at least one tube sheet. At least one tube sheet of the tube bundle is formed as a part of the container wall.

[0009] The two-phase heat transfer fluid is also called a refrigerant and is an external fluid in the container, and the electronic components are immersed in the liquid part thereof. The internal fluid present in the heat exchange tubes is a single-phase heat medium, for example, process water.

[0010] The tube bundle can have a number of heat exchange tubes arranged parallel to each other with two end tube sheets. The tube sheet is particularly suitable when using U-shaped tubes, in which case both a supply line and a discharge line of the internal fluid are attached to the tube sheet. Also, various arrangements of twisted tubes can be used for the tube bundle.

[0011] The tube bundle or the heat exchange tubes in the container can be arranged symmetrically about the left and right with respect to the container wall, and also asymmetrically about the left and right, or along an inclination.

[0012] The tube sheet determines the position and spacing of the heat exchange tubes within the tube bundle. The tube sheet and the heat exchange tubes form an independent module connected to the vessel wall. The tube sheet and the vessel wall can be provided with a fixed connection or a detachable connection. In both cases, the tube sheet stabilizes the surrounding vessel wall against deformation. In particular during operation, the tube sheet absorbs at least part of the deformation forces occurring in the surrounding vessel wall due to negative or positive pressure. The tube sheet is designed to be more stable than the vessel wall and thus serves to stabilize the vessel against deformation. The modular design of the tube bundle already has a structure that is stable against mechanical influences per se. The detachable connection to the vessel wall also enables the modules to be exchanged particularly easily. In particular, by easily exchanging modules with different cooling performance by changing the number of heat exchange tubes, it is possible to give the cooling system the corresponding flexibility. In particular, a structure for mechanically stabilizing the vessel is realized.

[0013] Inside the vessel, the electrical components are arranged in a bath of a liquid heat transfer fluid in a way suitable for cooling, and the electrical components are cooled by the vaporization of the liquid fluid. In this case, the non-condensable gas portion can be removed from the system before and / or during start-up of the operation. It is also possible to divide and arrange a plurality of independent tube bundles in the gas chamber of the vessel, and these tube bundles as a whole form a heat exchanger.

[0014] In an embodiment according to the invention, computer components and a liquid immersion cooling device, as well as associated power supplies, network connections, wiring connections, etc. can be arranged inside the vessel, and during operation, this vessel has an internal pressure different from the ambient pressure.

[0015] In this context, it is also advantageous to bundle the wiring for electrical connections, water connections, negative pressure connections, network connections into one bundle to minimize the feed-throughs into the vessel and in particular to reduce the risk of leakage when the system is in a negative or positive pressure state during operation.

[0016] In an advantageous embodiment, the container is maintained during operation at a pressure up to 200 hPa lower than the ambient atmospheric pressure, which contributes to lowering the boiling point of the two-phase heat transfer fluid and thereby reducing the operating temperature of the computer chip and other components. In some special embodiments, the pressure-controlled container can further have a pressure up to 500 hPa lower than the ambient pressure. As the pressure becomes even lower, the structural measures of the container wall according to the invention for correcting the pressure difference are particularly advantageous.

[0017] An embodiment of the cooling system according to the invention comprises a container designed to use a two-phase liquid immersion cooling system. This container includes a tank of a dielectric cooling fluid and a heat exchanger for condensing the dielectric fluid from the gas phase to the liquid. Furthermore, devices for holding computer components and devices for distributing electricity from a power supply system to the devices and components within the container can also be arranged.

[0018] For example, it goes without saying that a number of special connections are required to operate a computer system inside a container maintained at a negative pressure. In some embodiments of the system according to the invention, by using a series of optical fiber interfaces, connectivity within the container can be enabled and the fibers can be distributed to various holding devices of electronic components. In some embodiments of the container, sensors can be included for safe operation. These sensors can comprise 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.

[0019] These systems can, for example, comprise a pressure sensor for monitoring the pressure inside a pressure-controlled container, ensuring a state without significant leaks. Similarly, a gas sensor is arranged outside the pressure-controlled container to detect the presence of dielectric vapor that may flow out of the pressure-controlled container.

[0020] In addition, advantageously, the cooling system can also have a control device, which is provided to control the operation of the 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.

[0021] An advantageous embodiment of the cooling system according to the 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.

[0022] In an advantageous embodiment, a pick-and-place system can be installed that can transfer electronic components from a locking device to an operating position for replacement. This pick-and-place system can consist of a robotic arm or a linear drive. If the device is properly formed, component replacement can be carried out by a fully automatic pick-and-place system. Alternatively, gloves can be placed in a suitable container opening to replace the electronic components from the locking device to the operating position. This enables pick-and-place by manual access to the inside of the container.

[0023] In a preferred embodiment of the present invention, the container wall can have at least one recess as a penetration point for the heat exchange tubes, and this recess can be fluid-tightly covered by at least one tube sheet. In practice, the area of the penetration point is formed to be somewhat smaller than the area of the tube sheet, and the tube sheet completely covers the recess and is shaped so as to slightly overlap the container wall. This facilitates the connection between the tube sheet and the adjacent container wall as an adjacent joint component. Instead of a recess that spreads flat, there can be a number of recesses each having one surface, and each heat exchange tube can be individually passed through these recesses. The tube sheet is arranged inside or outside the container wall. However, the recesses can also be made to exactly match the outer shape of the tube sheet, in which case the tube sheet fits exactly to the container wall.

[0024] Advantageously, the tube sheet can be a flat metal plate having a penetration part for the heat exchange tubes, and the thickness of this plate corresponds to at least three times the thickness of a normal container wall. The support function and stability of the structure are almost determined by the material and thickness of the tube sheet. Therefore, for example, steel is suitable as the material, and the thickness of the plate is implemented with sufficient strength to improve stability.

[0025] In an advantageous embodiment of the present invention, the tube sheet can be welded to the container wall. The welded connection is a particularly stable material joining compared to other joining processes.

[0026] In an advantageous embodiment of the present invention, a connection box for distributing, diverting, or collecting a single-phase heat transfer medium that can pass through the heat exchange tubes can be arranged on at least one tube sheet outside the container. When there are a plurality of penetration points of the heat exchange tubes through the tube sheet or the container wall, additional connection boxes are respectively arranged for the single-phase heat transfer medium in the heat exchange tubes. Supply lines or discharge lines for the internal fluid also branch from these connection boxes, which are also called water boxes.

[0027] Advantageously, the connection box can be removably connected to the tube sheet. This allows for easy access to the heat exchange tubes within the tube bundle for maintenance purposes or for replacement. A fixed location can also be provided on the stable tube sheet using screw connections and sealing surfaces. This is because the material thickness of the tube sheet is greater than that of the container wall, resulting in a stable connection.

[0028] The heat exchange tubes can be implemented as smooth tubes or as finned tubes. In an advantageous embodiment, the heat exchange tubes can have integral fins formed on the outside of the tubes that wrap around in a spiral, and channels can be formed between the fins.

[0029] Such finned tubes are manufactured from smooth tubes that have undergone a forming process. Finned tubes are particularly suitable as components within heat exchangers that are highly efficient, compact, and extremely stable, with a high heat transfer rate. The tube surface is optimized for the specific heat transfer requirements of the application. With many options of materials including copper, copper alloys, steel, or titanium, materials suitable for each requirement can be used for various requirements, particularly with regard to durability and deformability.

[0030] Advantageously, the heat exchange tubes may be connected into the through-holes of the tube sheet by tube expansion, forming an airtight and pressure-resistant connection. In particular, most of the aforementioned material selections are ductile metals or metal alloys, and these metals can be used to expand the heat exchange tubes for connection to the tube sheet. Such mechanically performed connections result in stable joints that can withstand loads.

[0031] Advantageously, the heat exchange tubes may be soldered, glued, or welded to the tube sheet. This type of connection is airtight due to their material bonding and is also mechanically stable enough to obtain a compact modular tube bundle.

[0032] Advantageously, the tube bundle consisting of heat exchange tubes can have two tube sheets, and these tube sheets are connected to the remaining container wall at the opposite ends as recesses serving as through-holes. Thus, each tube sheet is connected to the container wall at each through-hole for the heat exchange tubes. The positioning of each tube sheet in this way stabilizes the container wall.

[0033] In an advantageous embodiment of the invention, the heat exchange tubes may be arranged linearly in the container between two end tube sheets. Thereby, the arrangement of the tube sheets and the heat exchange tubes connected thereto is formed such that the fluid flowing inside flows optimally.

[0034] Such a tube bundle preferably passes longitudinally along two container longitudinal sides close to the inner container wall over the entire length. Thus, the liquid heat transfer fluid can return as condensate into the reservoir near the container wall. In this side region, there is no or only a slight influence on the gas flow formed by the electrical components during the cooling process. For this purpose, the container can already have a shape that is hydrodynamically adapted to the flow of the heat transfer fluid.

[0035] Advantageously, the container may be implemented as a pressure vessel that can operate at negative and / or positive pressure. By controlling the pressure inside the container in which the system is operating, an improvement in the cooling capacity can be achieved. By mechanically stabilizing the solution according to the invention by arranging the tube sheets on the container wall, an important contribution can be made to the structural adaptation of the system as a whole.

[0036] In an advantageous embodiment of the invention, the fluid guide plate may be arranged to optimize the drainage behavior of the condensate or to distribute the gaseous heat transfer fluid. Such an additional guide plate results in an optimal drainage behavior for returning the condensate. Similarly, the vapor distribution of the gaseous heat transfer fluid in the cooling process is also advantageously affected thereby, optimizing the flow of the two-phase heat transfer fluid in the vapor phase, thereby increasing the rate and efficiency of condensation.

[0037] Advantageously, additional reinforcement devices may be arranged starting from the tube bundle and leading to the container wall, which can stabilize this container wall against static and dynamic loads. For this purpose, the additional reinforcement of the cooling system is mainly arranged near the sealing surface, which optimally releases the forces in the system in case of static and dynamic loads, improving the stability and tightness of the entire system.

[0038] Advantageously, the reinforcement device may be arranged starting from the tube sheet. Due to the stability of the entire tube bundle, the tube sheet is already a suitable location for absorbing and transmitting forces.

[0039] Examples of the invention will be described in more detail based on schematic diagrams.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0041] In all the figures, corresponding parts are denoted by the same reference numerals.

[0042] Figure 1 is a schematic view showing the front face of a cooling system 1 for liquid immersion cooling of electronic components. The cooling system 1 comprises a container 3 having a container wall 31, and the interior thereof can be filled with a two-phase heat transfer fluid. The two-phase heat transfer fluid is an external fluid within the container 3 and has a liquid heat transfer fluid portion 4 in which the electronic components are immersed and a gaseous heat transfer fluid portion 5. 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.

[0043] In this advantageous embodiment, the heat exchanger 6 in the gas chamber 5 consists of four tube bundles 7, and each tube bundle 7 has a plurality of heat exchange tubes 71 arranged parallel to each other. The heat exchange tubes 71 are fixed to a tube sheet 72. At least one tube sheet 72 of the tube bundle 7 is formed as the tip of the container wall 3. In the two tube bundles 7 visible in the left part of Figure 1, the overlapping region (dashed contour line) of the tube sheet 72 with respect to the recess 32 is also shown. Thereby, the tube sheet 72 completely covers the recess 32. Here, the tube sheet 72 is connected to the adjacent container wall 3 as a joining component by, for example, a welding seam not shown in Figure 1.

[0044] In the right part of Figure 1, a connection box 8 of the heat exchanger 6 has already been mounted on the tube sheet, and thus the heat exchange tubes 71 arranged behind it can only be partially seen through the openings. During operation of the cooling system 1, the internal fluid is introduced or discharged into the connection box 8 through these openings as a single-phase heat transfer medium. Since water is often used as the internal single-phase heat transfer medium, the connection box 8 is called a water box.

[0045] In FIG. 1, the container of the illustrated embodiment has a container wall 3 that protrudes inward and finally opens within the gas chamber, such 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 33. Thus, the container 3 is already surrounded by a stable outer frame.

[0046] FIG. 2 shows a schematic view of the tube bundle 7 of the cooling system. In this embodiment, the tube bundle 7 is formed by a plurality of heat exchange tubes 71 closely grouped together in the upper and lower regions between two tube sheets 72. Metal plates having through-holes for the heat exchange tubes 71 are respectively arranged one by one at the ends as the tube sheets 72. The material and thickness of the tube sheets 72 provide the support function and stability of the structure.

[0047] FIG. 3 is a schematic view showing the side of the cooling system 1. The electronic component 2 to be cooled is immersed in the liquid heat transfer fluid 4 below the surface 41 of the liquid fluid. The heat exchanger 6 is within the gas chamber 5.

[0048] In this advantageous embodiment, the heat exchanger 6 within the gas chamber 5 consists of the tube bundle 7 illustrated in FIG. 2, and each tube bundle 7 has a plurality of heat exchange tubes 71 arranged in parallel and fixed to the tube sheets 72. The two tube sheets 72 of the tube bundle 7 are firmly connected to the remaining container wall 3 at the opposing locations by means of recesses as through-holes. The heat exchange tubes 71 are linearly arranged within the container between the two end tube sheets 72.

[0049] A connection box 8 is arranged outside the container 3 on each tube sheet 72 for distributing, diverting or collecting the internal fluid that can pass through the heat exchange tubes 71.

[0050] In the first connection box 8, internal fluid is supplied via the supply line 81, and the internal fluid is distributed therein into the heat exchange tubes 71. The fluid recovered in the second connection box 8 is discharged via the discharge line 82 to a cooling device (not shown in FIG. 3).

[0051] The fluid guide plate 73 disposed in the tube bundle 7 stabilizes the entire structure and provides optimal discharge behavior for returning the condensed water to the liquid heat transfer fluid 4.

[0052] FIG. 4 shows a schematic diagram of the cooling system 1 when viewed from above inside the container 3. In all the connection boxes 8 on the inlet side, a single-phase heat transfer medium is intensively supplied via a branch from the supply line 81, recovered in the connection boxes 8 on the outlet side after passing through, and intensively discharged via the discharge line 82.

Description of Reference Numerals

[0053] 1 Cooling system 2 Electronic component 3 Container 31 Container wall 32 Recess 33 Metal profile frame 4 Liquid heat transfer fluid 41 Liquid fluid surface inside the container 5 Gaseous heat transfer medium, gas chamber 6 Heat exchanger 7 Tube bundle 71 Heat exchange tube 72 Tube sheet 73 Fluid guide plate 74 Reinforcement device 8 Connection box, water box 81 Supply line 82 Discharge line

Claims

1. A cooling system (1) for liquid immersion cooling of an electronic component (2), comprising: - a container (3) having a container wall (31), inside which a two-phase heat transfer fluid (4) capable of immersing the electronic component (2) can be filled, and the container (3) has a gas chamber (5) above the surface (41) of the liquid heat transfer fluid (4); - in a cooling system (1) provided with a heat exchanger (6) in the gas chamber (5) of the container (3) to form the liquid heat transfer fluid (4); - the heat exchanger (6) in the gas chamber (5) consists of at least one tube bundle (7) of a number of heat exchange tubes (71) arranged with each other, and the heat exchange tubes (71) are fixed to at least one tube sheet (72); - at least one of the tube sheets (72) of the tube bundle (7) is formed as a part of the container wall (31), characterized by the cooling system (1).

2. The container wall (31) has at least one recess (32) as a penetration part of the heat exchange tube (71), and the recess (32) is fluid-tightly covered by at least one of the tube sheets (72), characterized by the cooling system (1) according to Claim 1.

3. The tube sheet (72) is a flat metal plate having a through-hole for the heat exchange tube (71), and the thickness of the plate corresponds to at least three times the thickness of the normal container wall (31), characterized by the cooling system (1) according to Claim 1 or 2.

4. The tube sheet (72) is welded to the container wall (31), characterized by the cooling system (1) according to any one of Claims 1 to 3.

5. A connection box (8) for distributing, diverting or collecting the single-phase heat transfer medium capable of passing through the heat exchange tube (71) is arranged on at least one of the tube sheets (72) outside the container (3), characterized by the cooling system (1) according to any one of Claims 1 to 4.

6. The connection box (8) is removably connected to the tube sheet (72), characterized by the cooling system (1) according to Claim 5.

7. The heat exchange tube (71) has an integral fin formed on the outside of the tube that spirally surrounds, and a flow path is formed between the fins, characterized in that the cooling system (1) according to any one of claims 1 to 6.

8. The heat exchange tube (71) is connected into the through portion of the tube sheet (72) by expanding the tube, and an airtight and pressure-resistant connection is formed, characterized in that the cooling system (1) according to any one of claims 1 to 7.

9. The heat exchange tube (71) is soldered, adhered or welded to the tube sheet (72), characterized in that the cooling system (1) according to any one of claims 1 to 7.

10. The tube bundle (7) composed of heat exchange tubes (71) has two tube sheets (72), and the tube sheets (72) are connected to the remaining container wall (31) at opposing locations at the ends by recesses (32) as through locations, characterized in that the cooling system (1) according to any one of claims 1 to 9.

11. The heat exchange tube (71) is linearly arranged in the container (3) between the two end tube sheets (72), characterized in that the cooling system (1) according to claim 10.

12. The container (3) is implemented as a pressure vessel that can operate at negative pressure and / or positive pressure, characterized in that the cooling system (1) according to any one of claims 1 to 11.

13. The fluid guide plate (73) is arranged to optimize the drainage behavior of condensate or to distribute gaseous heat transfer fluid, characterized in that the cooling system (1) according to any one of claims 1 to 12.

14. An additional reinforcement device (74) is arranged starting from the tube bundle (7) and leading to the container wall (31), stabilizing the container wall (31) against static and dynamic loads, characterized in that the cooling system (1) according to any one of claims 1 to 13.

15. The reinforcement device (74) is arranged starting from the tube sheet (72), characterized in that the cooling system (1) according to claim 14.

Images