Cooling system for the liquid immersion cooling of electronic components

Abstract

The invention relates to a cooling system (1) for the liquid immersion cooling of electronic components, comprising - a vessel (3), which can be filled in the interior with two-phase heat-transfer fluid, in the liquid phase of which electronic components can be immersed, wherein the vessel (3) has a gas space above the surface of the liquid heat-transfer fluid, - a heat exchanger device in the gas space of the vessel (3) for forming liquid heat-transfer fluid, - at least one condenser unit (7), wherein the condenser unit (7) is in contact with the gas space of the vessel (3) by means of at least one fluid inlet opening (71) and at least one fluid outlet opening (72) for the mass transfer of gaseous medium to the condenser unit (7) or liquid medium from the condenser unit (7) and the condenser unit (7) has an outlet (79) via which a residual gas phase can be discharged, wherein - the condenser unit (7) has, downstream of the at least one fluid inlet opening (71) in the direction of flow (S), a tube bundle (73) with heat exchanger tubes (731), extending parallel to one another in their axial direction, in an enclosing housing (74), as a result of which a flow channel (75) is formed in the housing (74), - the tube bundle (73) is arranged in the housing (74) such that gaseous medium flows in the flow channel (75) along the axial direction of the heat exchanger tubes (731).

Description

[0001] Description

[0002] Cooling system for liquid immersion cooling of electronic components

[0003] The invention relates to a cooling system for liquid immersion cooling of electronic components according to the preamble of claim 1.

[0004] Liquid immersion cooling systems, such as two-phase immersion cooling systems, are an efficient cooling solution for electronic components that generate a lot of heat during operation. When the components are immersed in a two-phase heat transfer fluid, which preferably has a low boiling point, the heat generated by the electronic component can evaporate the surrounding liquid heat transfer fluid, thereby removing heat from the electronic component. A condenser device liquefies the gaseous heat transfer fluid, which is then returned to the reservoir for cooling.

[0005] A two-phase immersion cooling system with a cooling tank is known from US 10 512 192 B2. 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 vaporized fluid is guided into the condensation chamber for condensation by means of the vapor diversion structure. The condensation chamber is located within the cooling tank. A two-phase immersion cooling system with an immersion tank and a primary condenser for gaseous heat transfer fluid is known from US 10 966 349 B1. The primary condenser is in thermal communication with the interior volume of the immersion tank. The immersion cooling system also includes a vapor management system, which is connected to the headspace of the immersion tank on the flow side.The vapor management system allows periods of high vapor production to be managed effectively by removing fluid vapor and other gases from the headspace of the immersion tank, condensing the vapor to liquid, and returning the liquid to the immersion tank.

[0006] Furthermore, a cooling system for computer components is known from US Pat. No. 1,0477,726 B1. A pressure-controlled container contains a heat-conducting, dielectric heat transfer fluid in liquid and gaseous phases, which has a boiling point below 80°C at atmospheric pressure. Computer components are arranged in the container and are at least partially immersed in the liquid phase of the heat transfer fluid. A condenser condenses the dielectric gas-phase fluid evaporated by the heat generated by the computer components into a dielectric liquid-phase fluid. The internal pressure in the pressure-controlled container is reduced to as low as 650 hPa. By controlling the pressure in the container at which the system operates, the user can influence the temperature at which the dielectric fluid evaporates. This allows for increased cooling performance.The operation of a computer system within a pressure-controlled vessel at an operating pressure that deviates from the ambient pressure usually requires a structural adaptation of the system as a whole.

[0007] From the publication US 2021 / 0 153 392 A1 a cooling system with a

[0008] A container is known that can be filled with a two-phase heat transfer fluid as a coolant, into whose liquid phase electronic components can be immersed. The container has a gas space above the surface of the liquid heat transfer fluid. A separate external condenser device is arranged above the container and is configured to condense the vapor phase of the heat transfer fluid and return it as a liquid coolant to the container with the electronic components. For this purpose, the system comprises return and supply lines that are connected to both the condenser device and the container to form a heat exchange loop. The system also comprises a collecting vessel that is arranged on the supply line and is configured to collect the condensed, liquid heat transfer fluid before the coolant is supplied to the container.This accumulator also provides reserve cooling capacity for the cooling system.

[0009] From the document EP 3 453235 B1, a cooling system for immersion cooling of electronic components is known, comprising a pressure-tight tank configured to contain heat transfer fluid in liquid form, into which the electronic equipment is immersed. Furthermore, a vapor space is present above a surface of the liquid heat transfer fluid. A condenser is arranged outside the pressure-tight tank, wherein the condenser has an inlet connected to the vapor space by a riser pipe and configured to receive heat transfer fluid vapor. Furthermore, the condenser has a tightly sealable vapor outlet for residual gases and a condensate outlet with a condensate return line to the tank. The condensate return line is designed such that condensed heat transfer fluid can flow back from the condensate outlet to the tank.Additional condenser tubes for liquefying gaseous heat transfer fluid may also be present within the tank. The invention is based on the object of further developing a cooling system for liquid immersion cooling of electronic components with respect to a heat exchanger device.

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

[0011] The invention includes a cooling system for liquid immersion cooling of electronic components. The cooling system comprises:

[0012] - a container which can be filled with a two-phase heat transfer fluid, into the liquid phase of which electronic components can be immersed, the container having a gas space above the surface of the liquid heat transfer fluid,

[0013] - a heat exchanger device in the gas space of the vessel for forming liquid heat transfer fluid,

[0014] - at least one condenser unit, wherein the condenser unit is in contact with the gas space of the container by means of at least one fluid inlet opening for the mass exchange of gaseous medium to the condenser unit or liquid medium from the condenser unit and the condenser unit has an outlet via which a residual gas phase can be discharged.

[0015] According to the invention, the condenser unit comprises, downstream of the at least one fluid inlet opening in the flow direction, a tube bundle with heat exchanger tubes running parallel to one another in the axial direction in an enclosing housing, thereby forming a flow channel in the housing. Furthermore, the tube bundle is arranged in the housing such that gaseous medium flows in the flow channel along the axial direction of the heat exchanger tubes. The invention is based on the idea that the housing of the condenser unit, with an internal tube bundle of straight and parallel heat exchanger tubes, essentially forms an elongated cooling section, in which gaseous heat transfer fluid originating from the container is cooled and liquefied.The heat transfer fluid condensed on the heat exchanger tubes drips onto the housing base, which preferably has a sufficient inclination relative to the horizontal toward the fluid outlet opening to allow the liquid heat transfer fluid to flow back through the fluid outlet opening into the container. The condensation process continuously reduces the amount of gaseous heat transfer fluid, creating a negative pressure in the housing of the condenser unit relative to the container. This results in gaseous heat transfer fluid continuously flowing from the gas space of the container into the housing of the condenser unit through at least one fluid inlet opening. The system therefore regulates itself independently, depending on the pressure and the heat transfer surface.A condenser unit can also be individually designed in multiple versions, each at different positions inside or outside the container, depending on the cooling requirements.

[0016] The particular advantage of the solution according to the invention is the particularly long cooling section formed by heat exchanger tubes, along which the gaseous fluid is forced inside an elongated housing.

[0017] The container can be designed to be pressure-tight. Advantageously, the container can be designed as a pressure vessel that can be operated at negative and / or positive pressure. By controlling the pressure in the container at which the cooling system operates, increased cooling capacity can be achieved. The heat exchanger device in the gas space preferably consists of at least one tube bundle formed from several heat exchanger tubes arranged parallel to one another. A tube bundle can have several heat exchanger tubes arranged parallel to one another with two end tube plates.

[0018] The heat exchanger tubes are preferably finned tubes, which are made from smooth tubes and subjected to a forming process. They are particularly suitable as components in highly efficient, compact, and extremely stable heat exchangers with a high heat transfer coefficient. The tube surfaces are optimized for the specific heat transfer requirements of the application. A wide selection of materials, including copper, copper alloys, steels, titanium, and titanium alloys, ensures that suitable materials are available for different needs, particularly in terms of durability and formability.

[0019] The two-phase heat transfer fluid, also known as the refrigerant, represents the outer fluid in the vessel, in whose liquid portion the electronic components are immersed. The inner fluid in the heat exchanger tubes is typically a single-phase heat transfer medium, such as process water, glycol, or thermal oil. However, a two-phase medium can also be used here in conjunction with a refrigeration circuit.

[0020] In the container, the electronic components are arranged in a suitable manner in a bath of liquid heat transfer fluid, which is cooled by evaporation of the liquid fluid. This allows the proportion of non-condensable gases to be effectively removed from the system before or during commissioning. In the embodiment according to the invention, the computing components and immersion cooling devices, as well as the associated power supplies, network connections, wiring connections, and the like, can be arranged in the container, which has an internal pressure that differs from ambient pressure during operation.

[0021] In this context, it is also advantageous to combine power, water, vacuum and network connections in a bundle of lines to minimize penetrations into the vessel and to reduce the risk of leaks, especially when the system is under vacuum or overpressure during operation.

[0022] In advantageous embodiments, the vessel is maintained at up to 200 hPa below atmospheric ambient pressure during operation, which helps lower the boiling point of the two-phase heat transfer fluid and thereby reduce the operating temperature of the computer chips and other components. In some specific embodiments, the pressure-controlled vessel can be designed for an even lower pressure of up to 500 hPa below ambient pressure.

[0023] Embodiments of the cooling system according to the invention comprise a container for dielectric cooling fluid, a heat exchanger device, and a condenser unit for condensing the dielectric fluid from the gaseous phase to a liquid. The condenser unit, located outside or inside the container, is intended to condense the remaining gaseous heat transfer fluid, which also contains certain amounts of air and water vapor, into liquid heat transfer fluid to the greatest possible extent. Ideally, the remaining heat transfer fluid is almost completely condensed from the gas phase, so that essentially only air and water vapor remain as the residual gas phase. The goal of separating liquid heat transfer fluid is to keep the water vapor in the gas phase through a suitable cooling capacity of the system. This residual gas mixture is discharged from the cooling system via an outlet of the condenser unit.

[0024] Additionally, devices for holding computer components and distributing power from the power system to the devices and components located within the container may be provided. It is understood that a variety of specialized connections are used to operate a computer system within a container, for example, maintained at a vacuum. Some embodiments of the system according to the invention may utilize a series of fiber optic interfaces to enable connectivity within the container and to distribute the fibers to the various holding devices for the electronic components. Some embodiments of the container may include monitoring sensors for safe operation. These sensors may include temperature sensors, fluid level sensors, pressure sensors, position sensors, electrical sensors, and / or cameras to ensure and automate the operation of the system.

[0025] These systems may, for example, include pressure sensors inside the pressure-controlled vessel that monitor the pressure to ensure there are no significant leaks. Gas sensors located on the outside of the pressure-controlled vessel may also detect the presence of any dielectric vapor escaping from the pressure-controlled vessel.

[0026] In addition, the cooling system may advantageously comprise a control device designed to regulate the operation of the fluid circulation, for example as a function of the temperature of the two-phase heat transfer fluid and the pressure conditions in the container.

[0027] In a preferred embodiment of the invention, the flow channel can vary in its passage cross-section for the fluid in the direction of flow. This measure is intended to concentrate the flow of the heat transfer fluid onto the heat exchanger tubes, which run parallel to each other in the axial direction, and prevent backflow.

[0028] Advantageously, the flow channel can comprise a plurality of chambers connected by connecting channels with a smaller cross-section. This allows the gaseous heat transfer fluid to be directed from chamber to chamber until liquefaction occurs. This increases the residence time in the respective chambers and controls the flow via the pressure gradient established at the constrictions.

[0029] It is also advantageous that the tube bundle containing the heat exchanger tubes can be routed through the chambers and connecting channels in the flow channel. This measure also concentrates the flow of the heat transfer fluid onto the heat exchanger tubes, which run axially parallel to each other, and prevents backflow.

[0030] In an advantageous embodiment of the invention, guide structures for the gaseous fluid can be arranged. The vapor is thus forced to flow along the heat exchanger surface of the tube bundle toward the outlet in order to condense as much refrigerant as possible.

[0031] In an advantageous embodiment of the invention, the condenser unit can be arranged inside or outside the container. Depending on the structural design and space requirements, the condenser unit is a standalone module that only needs to be connected in some suitable manner to the gas space of the container for mass transfer of the fluid.

[0032] Advantageously, a condenser unit arranged within the vessel can be located above or next to the heat exchanger in the gas space of the vessel. These areas contain, in particular, a gaseous fluid phase that is already enriched with residual gases, such as air components or water vapor, and is available for further condensation.

[0033] In a preferred embodiment of the invention, a collecting container can be arranged downstream of the condenser unit outlet, through which the residual gas phase can be discharged. This container also ensures that no air from the environment can enter the cooling system. The container can be an expandable elastic balloon or a bellows with variable volume.

[0034] In a particularly preferred embodiment, a drying unit for separating water vapor from the gas phase can be arranged between the outlet and the collection tank. The pressure level in the entire cooling system often changes during load changes. If necessary, outside air or residual gas can be introduced into the cooling system via the collection tank and the drying unit to equalize the pressure. Silica gel, which binds water vapor, is suitable for such drying units.

[0035] In a further advantageous embodiment of the invention, a vacuum pump can be arranged downstream of the outlet, through which the residual gas phase can be removed. In this case, the residual gas phase consisting of water vapor and air at the outlet can also be at a negative pressure compared to the ambient air, since a vacuum pump always ensures that the residual gas flows outward.

[0036] Advantageously, the heat exchanger device and the condenser unit can have a common supply unit for a first single-phase heat transfer medium for cooling. This ensures that both units are at a uniform temperature level, which is suitable for the separation process of the heat exchanger fluid.

[0037] In a preferred embodiment of the invention, the condenser unit can have a second supply unit for a second single-phase heat transfer medium for cooling. A separate, different temperature level can then be set in the condenser unit for further effective separation of the individual phase components.

[0038] In a particularly preferred embodiment, the condenser unit can be designed so that it can be operated for cooling at a lower temperature of the single-phase heat transfer medium than the heat exchanger unit. In particular, it is important to ensure that pressure and temperature conditions are selected that are not below the dew point of the water component in order to retain the water vapor in the residual gas phase and to be able to dissipate it. The condenser unit can be used optimally within this pressure-temperature range.

[0039] Embodiments of the invention are explained in more detail with reference to the schematic drawings.

[0040] Showing:

[0041] Fig. 1 is a schematic front view of a cooling system with a condenser unit, Fig. 2 is a schematic side view of a cooling system with a condenser unit, Fig. 3 is a further side view of a cooling system with a condenser unit, and

[0042] Fig. 4 another side view of a cooling system with condenser unit.

[0043] Corresponding parts are provided with the same reference numerals in all figures.

[0044] Fig. 1 shows a schematic front view of a cooling system 1 for liquid immersion cooling of electronic components 2. The cooling system 1 comprises a container 3, which is filled internally with a two-phase heat transfer fluid. The two-phase heat transfer fluid represents the external fluid located in the container 3, with a liquid heat transfer fluid portion 4 in which the electronic components 2 are immersed and a gas space 5 with a gaseous heat transfer fluid portion. A heat exchanger device 6 is arranged in the gas space 5 of the container 3 to form liquid heat transfer fluid 4.

[0045] In this advantageous embodiment, the heat exchanger device 6 in the gas space 5 consists of tube bundles, each with several heat exchanger tubes arranged parallel to one another.

[0046] In the illustrated embodiment in Fig. 1, the container 3 is slightly tapered in the area of ​​the liquid heat transfer fluid 4, with the container wall projecting inward and only opening in the gas space 5. The shape of the container 3 is supported by a metal profile frame 31. The container 3 is therefore already enclosed by a stabilizing outer frame.

[0047] A condenser unit 7 is arranged on the left side outside the container 3 and on the right side inside the container 3. The condenser unit 7 is connected to the gas space 5 of the container 3 by means of a fluid inlet opening 71 for the mass transfer of gaseous medium. Likewise, at the end of a sloping bottom surface of the housing 74, a fluid outlet opening 72 for liquefied heat transfer fluid to the container 3 is arranged, through which liquid heat transfer fluid from the condenser unit 7 returns to the container 3.

[0048] To regulate the mass transfer, a valve 710 is installed in the fluid inlet opening 71 and a valve 720 is installed in the fluid outlet opening 72. A gaseous mixture of heat transfer fluid, air, and water vapor is withdrawn from the vessel 3 cyclically or continuously via the valve 710 of the fluid inlet opening 71. Only liquid heat transfer fluid is returned to the vessel 3 via the valve 720 of the fluid outlet opening 72.

[0049] The remaining residual gas phase, which after almost complete condensation of the heat transfer fluid essentially consists only of air and water vapor, is discharged to the outside via an outlet 79 by means of a valve 910. For additional separation of water vapor, a drying unit 8 for separating water vapor from the gas phase is arranged between outlet 79 and collection tank 9.

[0050] Depending on the pressure level, the residual gas phase can be discharged directly to the environment. Alternatively, the residual gas phase can also be discharged via a vacuum pump 10. For this purpose, the outlet 79 is connected to a vacuum pump 10 via a supply line 101, which, via a valve control 1010, regulates the residual gas flow to the outside via a discharge line 102 of the vacuum pump 10.

[0051] Alternatively or additionally, the residual gas phase can also be fed via a supply line 91 with valve 910 to a collecting tank 9, which can be designed as a volume-expanding bellows to generate a negative pressure. If the valve 910 to the collecting tank 9 is closed during operation, the residual gas can be discharged via the discharge line 92 of the collecting tank 9 with the valve 920 open.

[0052] Fig. 2 shows a schematic side view of a cooling system 1 with a condenser unit 7. The condenser unit 7 is attached to the long side outside the container 3. The fluid inlet opening 71 connects the gas space of the container 3 located behind it with the condenser unit 7. Gaseous fluid flows out of the container 3 through this fluid inlet opening 71. The fluid outlet opening 72 is located at the end of a slope at the lowest point of the bottom surface 741 of the housing 74 of the condenser unit 7. The condensed liquid fluid returns to the container 3 via this fluid outlet opening 72. The gaseous fluid flowing in via the fluid inlet opening 71 strikes the tube bundle 73 consisting of a plurality of heat exchanger tubes 731 and is guided in the flow direction S essentially axially along the heat exchanger tubes 731 in the flow channel 75.Guide structures 78 are provided for the targeted redirection of the gaseous fluid, forcing the gaseous fluid to flow preferentially along the tube bundle 73 towards the outlet 79. During the condensation process, the volume of the gaseous fluid and thus the pressure is continuously reduced along the tube bundle 73. The resulting pressure gradient creates a negative pressure in the condenser unit 7 relative to the container 3, whereby gaseous fluid continuously flows through the fluid inlet opening 71. In the area of ​​the outlet 79, the non-condensable gas components, such as air components and water vapor, accumulate as a result of the continuous condensation of the gaseous fluid. These non-condensable gas components are then discharged from the cooling system 1 via the outlet 79. Fig. 3 schematically shows another side view of a cooling system 1 with a condenser unit 7. In the same way as in Fig.As already shown in Figure 2, the condenser unit 7 is arranged on the upper outer side of the container 3 with a fluid inlet opening 71 and a fluid outlet opening 72. The bottom surface 741 of the housing 74 is again designed with a certain gradient toward the fluid outlet opening 72.

[0053] On the top side of the housing 74, in the flow direction S, depressions 742 are formed, resulting in the formation of chambers 76 that allow mass transfer for the gaseous fluid via narrowing connecting channels 77. However, these constrictions still have a sufficient passage cross-section D through which the tube bundle 73 with the heat exchanger tubes 731 is passed. Consequently, a series of successive chambers 76 are arranged in the flow channel 75 along the flow direction S, each of which increases the residence time of the gaseous fluid and prevents backflow of the gaseous fluid. At the outlet 79, in particular, the non-condensable gas components are discharged from the cooling system 1.

[0054] Fig. 4 schematically shows a further side view of a cooling system 1 with condenser unit 7 in a configuration with a tube bundle finned heat exchanger 73. In this embodiment, the fins act as guide structures 78, which on the one hand guide the gaseous fluid and also form a plurality of chambers 76 through which gaseous fluid is guided from the fluid inlet opening 71 in the flow direction S to the outlet 79. The bottom surface 741 of the housing 74 is in turn designed to be inclined towards the fluid outlet opening 72 in order to return the condensed liquid fluid to the container 3. In the tube bundle finned heat exchanger 73, the tubes are guided parallel to one another over the length of the housing 74 and are connected in series at the ends by pipe bends.The guide structures 78, designed as fins, are provided with passages as connecting channels 77 in the flow direction S, so that the gaseous fluid flows essentially axially along the heat exchanger tubes 731. The design of the heat exchanger tubes 731 is preferably straight, but can also include other elongated shapes, such as elongated spirally coiled tubes.

[0055] List of reference symbols Cooling system Electronic components Container Metal profile frame Heat transfer fluid Surface of the liquid heat transfer fluid Gas space Heat exchanger device Condenser unit Fluid inlet opening Valve Fluid outlet opening Valve Tube bundle Heat exchanger tubes Housing Bottom surface of the housing Depressions Flow channel Chambers Connecting channels Conductive structures Outlet Drying unit

[0056] 9 collecting container, bellows

[0057] 91 Supply line collection container

[0058] 910 Valve of the supply line collection tank

[0059] 92 Discharge line collection container

[0060] 920 Valve of the discharge line collection tank

[0061] 10 Vacuum pump

[0062] 101 Vacuum pump supply line

[0063] 1010 Vacuum pump supply line valve

[0064] 102 Vacuum pump discharge line

[0065] D passage cross-section

[0066] S Flow direction

Claims

Patent claims 1 . Cooling system (1) for liquid immersion cooling of electronic components (2), comprising - a container (3) which can be filled inside with a two-phase heat transfer fluid (4), in the liquid phase of which electronic components (2) can be immersed, wherein the container (3) has a gas space (5) above the surface (41) of the liquid heat transfer fluid (4), - a heat exchanger device (6) in the gas space (5) of the container (3) for forming liquid heat transfer fluid (4), - at least one condenser unit (7), wherein the condenser unit (7) is in contact with the gas space (5) of the container (3) by means of at least one fluid inlet opening (71) and at least one fluid outlet opening (72) for the mass exchange of gaseous medium to the condenser unit (7) or liquid medium from the condenser unit (7) and the Condenser unit (7) has an outlet (79) through which a residual gas phase can be discharged, characterized in that - that the condenser unit (7) has, in the flow direction (S) after the at least one fluid inlet opening (71), a tube bundle (73) with heat exchanger tubes (731) running parallel to one another in the axial direction in an enclosing housing (74), whereby in a flow channel (75) is formed in the housing (74), - that the tube bundle (73) is arranged in the housing (74) such that gaseous medium flows in the flow channel (75) along the axial direction of the heat exchanger tubes (731).

2. Cooling system (1) according to claim 1, characterized in that the flow channel (75) varies in its passage cross-section (D) for the fluid in the flow direction (S).

3. Cooling system (1) according to claim 1 or 2, characterized in that the flow channel (75) has a plurality of chambers (76) which are connected by connecting channels (77) with a smaller passage cross-section (D).

4. Cooling system (1) according to claim 3, characterized in that in the flow channel (75) the tube bundle (73) with the heat exchanger tubes (731) are guided through the chambers (76) and through the connecting channels (77).

5. Cooling system (1) according to one of claims 1 to 4, characterized in that guide structures (78) for the gaseous fluid are arranged.

6. Cooling system (1) according to one of claims 1 to 5, characterized in that the condenser unit (7) is arranged inside or outside the container (3).

7. Cooling system (1) according to one of claims 1 to 6, characterized in that a condenser unit (7) arranged within the container (3) is arranged above or next to the heat exchanger device (6) in the gas space (5) of the container (3).

8. Cooling system (1) according to one of claims 1 to 7, characterized in that a collecting container (9) is arranged downstream of the outlet (79) of the condenser unit (7), via which the residual gas phase can be discharged.

9. Cooling system (1) according to claim 8, characterized in that a drying unit (8) for separating water vapor from the gas phase is arranged between the outlet (79) and the collecting container (9).

10. Cooling system (1) according to one of claims 1 to 7, characterized in that a vacuum pump (10) is arranged downstream of the outlet (79), via which the residual gas phase can be discharged.

11. Cooling system (1) according to one of claims 1 to 10, characterized in that the heat exchanger device (6) and the condenser unit (7) have a common supply unit for a first single-phase heat transfer medium for cooling.

12. Cooling system (1) according to one of claims 1 to 10, characterized in that the condenser unit (7) has a second supply unit for a second single-phase heat transfer medium for cooling.

13. Cooling system (1) according to one of claims 1 to 10, characterized in that the condenser unit (7) is designed such that it can be operated for cooling at a lower temperature of the single-phase heat transfer medium than the heat exchanger device (6).

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