Adjusting the dielectric fluid level of an immersion tank

Abstract

The present invention relates to an installation (1) comprising: - an immersion tank (3) comprising retaining means (8) configured to receive computing devices (2) and a dielectric fluid (4), the retaining means (8) being positioned in the immersion tank (3) so that the computing devices (2) are immersed in the dielectric fluid (4); - a spill tank (12) placed next to the immersion tank (3), the spill tank (12) comprising dielectric fluid (4) and being separated from the immersion tank (3) by a separating wall (7);a window (13) having a lower edge (14) being formed in the partition wall (7) so as to put the immersion tank (3) and the spill tank (12) into fluid communication, a level of dielectric fluid (4) in the immersion tank (3) being higher than a level of dielectric fluid (4) in the spill tank (12) so that the dielectric fluid (4) pours through the window (13) into the spill tank (12) when its level reaches the lower edge (14) of the window (13). Figure for abstract: Fig. 1;

Description

Title of the invention: Adjustment of the dielectric fluid level of an immersion tank Technical field

[0001] The present invention relates to the general technical field of immersion cooling of computer devices such as computer servers. STATE OF THE ART

[0002] Immersion cooling is an innovative cooling technology for computing devices that offers significant advantages over traditional air cooling methods. Immersion cooling involves immersing computing devices, typically computer servers, in immersion tanks forming a bath of dielectric heat transfer fluid.

[0003] This passive cooling process is very efficient. Compared to air or water cooling, immersion cooling can drastically reduce cooling energy consumption.

[0004] The dielectric fluid is chosen so as to maximize the immersion cooling capacity. The dielectric fluid may, for example, comprise a synthetic hydrocarbon-based fluid. However, the alkanes present in these fluids degrade plastic materials and therefore reduce the service life of the cables. In addition to harming the proper functioning of the submerged computing devices, the degradation of the cables has the effect of generating waste which is likely to damage the cooling circuit.

[0005] The computer devices are therefore positioned in the immersion tank so as to minimize the cable surface in contact with the fluid. A pump placed in the upper part of the immersion tank regulates the height of the fluid to limit these contacts. The sucked fluid is also filtered in order to recover pieces of plastic and other particles present in the fluid. However, in use, it remains necessary to clean the filter very regularly if one wishes to avoid any risk of damage to the electronic components of the computer devices and to protect the cooling circuit. Statement of the invention

[0006] An aim of the present application is to remedy the aforementioned drawbacks. More specifically, an aim of the present invention is to propose an installation for the immersion cooling of computer devices, such as servers. computers, reducing the risk of damage to electrical cables.

[0007] To this end, according to a first aspect, an installation is proposed comprising: - an immersion tank comprising retaining means configured to receive computer devices and a dielectric fluid, the retaining means being positioned in the immersion tank so that the computer devices are immersed in the dielectric fluid; and - a spill tray placed next to the immersion tray, the spill tray comprising dielectric fluid and being separated from the immersion tray by a partition wall. In addition, a window having a lower edge is formed in the partition wall so as to fluidly connect the immersion tank and the spill tank and a dielectric fluid level in the immersion tank is higher than a dielectric fluid level in the spill tank such that the dielectric fluid spills through the window into the spill tank when its level reaches the lower edge of the window.

[0008] Some preferred but non-limiting features of the installation according to the first aspect are the following, taken individually or in combination: - the installation further comprises a window adjustment device configured to adjust the level of dielectric fluid in the immersion tank; - the installation further comprises a dielectric fluid cooling system comprising a pump configured to draw fluid into the spill tank and a heat exchanger configured to cool the dielectric fluid drawn by the pump; - the installation further comprises a filter in the spill tank configured to filter the dielectric fluid; - the spill tray comprises a first compartment into which the window opens and a second compartment connected to the pump, the filter being positioned between the first compartment and the second compartment; - the first compartment is positioned above the second compartment so that the dielectric fluid flows by gravity from the first compartment to the second compartment, a wall of the first compartment being inclined relative to a horizontal plane and the filter being positioned at a low point of the wall; - the installation includes several windows distributed along the length of the immersion tank; - the installation further comprises at least one computer device immersed in the dielectric fluid and mounted in the retaining means; and / or - the installation further comprises at least one electrical cable comprising a terminal electrically connected to the computing device and a cable portion extending from the terminal, the lower edge of the window being positioned relative to the mounting means such that the terminal is immersed in the dielectric fluid while the cable portion is at a distance from the dielectric fluid.

[0009] According to a second aspect, there is provided a data center comprising an installation according to the first aspect and computing devices mounted in the retaining means. DESCRIPTION OF FIGURES

[0010] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0011] [Fig. 1] illustrates schematically and in perspective an example of an installation in accordance with one embodiment;

[0012] [Fig.2] is a top view of an example of an installation according to one embodiment;

[0013] [Fig.3] is a sectional view of the example of [Fig.2], in a plane passing through the computing devices;

[0014] [Fig.4] is a sectional view of the example of [Fig.2], in a plane passing through the spill tray; and

[0015] [Fig.5] illustrates an example of the embodiment of a window that can be used in an installation.

[0016] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0017] An installation 1 for the immersion cooling of computer devices 2, such as computer servers, comprises an immersion tank 3 filled with a dielectric fluid 4 and non-corrosive in which the computer devices 2 are immersed, and a system for cooling the dielectric fluid 4.

[0018] The immersion tank 3 comprises a bottom wall 5 configured to be placed on a generally horizontal support (for example the ground), side walls 6, 7 which extend from the bottom wall 5, and an opening, which extends opposite the bottom wall 5. The side walls 6, 7 give the immersion tank 3 a generally rectangular cross-section. The installation 1 further comprises a cover configured to cover the opening and close the immersion tank 3.

[0019] In the following, the invention will be described with reference to the operating configuration of the installation 1. In particular, “upper” (respectively “top”) and “lower” (respectively “bottom”) are used with reference to the installation 1, a lower part being arranged on the side of the bottom of the immersion tank 3 while an upper part will be arranged on the side of the opening.

[0020] The immersion tank 3 comprises means 8 for retaining the computer devices 2, for example racks, mounted on two opposite side walls 6, 7 and configured to hold each computer device 2 in position relative to the side wall 7. Each computer device 2 has an upper edge 9, configured to be placed facing the cover, comprising connectors configured to be connected to a network via electrical cables. Each electrical cable comprises for this purpose a terminal 28, configured to be connected on the upper edge 9 of the computer device 2 to the corresponding connector, and a cable portion 29 configured to electrically connect the terminal 28 to the computer network. The retaining means 8 are furthermore positioned so that, in use, the upper edge 9 of the computer devices 2 is immersed in the dielectric fluid 4.

[0021] The dielectric fluid 4 may comprise a synthetic fluid 3 based on hydrocarbons, for example isoparaphine. Such a dielectric fluid 4 is in fact non-corrosive and has a thermal conductivity of approximately 0.137 W / km at 25°C, i.e. almost six times that of air. The function of the dielectric fluid 4 is to absorb the heat generated by the computer devices 2 which are immersed. It is continuously cooled by a cooling system comprising a pump 10 configured to suck in the dielectric fluid 4 and discharge it into a heat exchanger 11, where it is cooled before being discharged into the immersion tank 3.

[0022] In order to ensure that the computer devices 2 remain immersed in the dielectric fluid 4, while limiting the risks of damage to the plastic materials, the installation 1 further comprises a spill tank 12 placed next to the immersion tank 3, the spill tank 12 also comprising dielectric fluid 4 and being separated from the immersion tank 3 by one of the side walls 7. The spill tank 12 and the immersion tank 3 are therefore part of the same tank and are simply separated by the side wall 7.

[0023] In addition, a window 13 is formed in the side wall 7 in order to put the immersion tank 3 and the spill tank 12 into fluid communication. The window 13 has a lower edge 14 (bottom side), an upper edge (lid side) which are connected by lateral edges. The level of dielectric fluid 4 in the immersion tank 3 is also higher than the level of fluid 3 in the spill tank so that the dielectric fluid 4 pours through the window 13 into the spill tank 12 when its level reaches the lower edge 14 of the window 13.

[0024] By fluid level 3, we will understand here the distance, measured along an axis normal to the horizontal support, between the support and the surface of the fluid 3.

[0025] The adjustment of the fluid level 3 in the immersion tank 3 is therefore passive and dictated by the position of the lower edge 14 of the window 13. Indeed, as soon as the fluid level 3 reaches the lower edge 14, the excess dielectric fluid 4 overflows and flows automatically into the overflow tank 12, thus guaranteeing a stable and controlled fluid level 3 in the immersion tank 3. There is therefore no longer any risk of wetting the cable portions 29, which are made of plastic and deteriorate in contact with the dielectric fluid 4. The terminals 28 being more resistant to the dielectric fluid, they preferably remain immersed in the dielectric fluid 4 in order to guarantee that the computer devices are immersed at all times.

[0026] In order to ensure that the computing devices 2 remain submerged while avoiding wetting the cable portions 29, the lower edge 14 of the window 13 is placed at a distance of between 7 mm and 12 mm from the upper edge 9 of the computing devices 2 and a distance of between 30 mm and 45 mm from the retaining devices 8, typically of the order of 35 to 40 mm.

[0027] The window 13 may extend over all or part of the length of the lateral separation wall 7. By length, here, we mean the dimension of the lateral separation wall 7 in a plane parallel to the ground between the two lateral walls 6 which are connected to the lateral separation wall 7. Alternatively, the window 13 may be segmented and be formed of several disjointed window segments 13 distributed along the length of the lateral separation wall 7. This configuration in fact makes it possible to stiffen the lateral separation wall 7, while guaranteeing the ability of the windows to maintain the desired level of dielectric fluid in the immersion tank 3.

[0028] In one embodiment, the installation 1 comprises an adjustment device 15 configured to adjust the level of dielectric fluid 4 in the immersion tank 3. The adjustment device 15 may for example comprise a shutter mounted on the separating side wall 7 so as to reveal or cover all or part of the window 13. In one embodiment, the shutter comprises a plate 16 having an upper edge configured to be placed against the window 13 and fixing lugs 17 configured to fix the plate 16 on the separating side wall 7. The upper edge of the plate 16 then corresponds to the lower edge 14 of the window 13. By way of example, each fixing lug 17 may comprise an oblong slot 18 configured to receive a fixing bolt 19 in order to fix the shutter on the separating side wall 7.The position of the shutter can then be adjusted by loosening the bolts 19 and translating the shutter (the bolts 19 sliding along the oblong slot 18) relative to the separating side wall 7, which has the effect of changing the position of the upper edge of the plate. 16 (which corresponds to the lower edge 14 of the window 13) and therefore the overflow level of the dielectric fluid 4 in the overflow tank 12.

[0029] When the window 13 is segmented, a single adjustment device 15 can be used to modify the position of the lower border 14 of the window segments 13. Alternatively, each window segment 13 can comprise its own adjustment device 15.

[0030] Advantageously, the presence of an adjustment device 15 makes it possible to adapt the position of the lower edge 14 of the window 13 according to the level of dielectric fluid 4 required in the immersion tank 3. The level of fluid 3 required can in fact vary according to the number of computer devices 2 installed in the immersion tank 3: for the same volume of dielectric fluid 4, the level of fluid 3 will in fact be lower when a single computer device 2 is installed in the immersion tank 3 than when several computer devices 2 are installed, for example, twenty-four. This adjustment of the position of the lower edge 14 of the window 13 also makes it possible to take into account any leaks likely to reduce the volume of fluid 3 in the immersion tank 3 over time.

[0031] The spill tray 12 comprises a bottom wall 20, side walls 21, 7 and an opening. One of the side walls of the spill tray 12 corresponds to the separating side wall 7. Furthermore, the cover of the installation 1 is configured to also cover the opening of the spill tray 12. The spill tray 12 preferably extends over the entire length of the immersion tray 3.

[0032] Since the volume of the immersion tank 3 is substantial, the side walls 6, 7 of the immersion tank 3 must be sufficiently rigid to guarantee the integrity of the immersion tank 3.

[0033] The cooling system of the dielectric fluid 4 comprises the pump 10, which is configured to draw dielectric fluid 4 into the spill tank 12, and the heat exchanger 11 configured to cool the dielectric fluid 4 drawn by the pump 10. The cooled dielectric fluid 4 is then discharged into the immersion tank 3 in order to cool the computing devices 2. The cooling system further comprises a filter, mounted in the spill tank 12 and configured to filter the dielectric fluid 4 before it is drawn by the pump 10.

[0034] In one embodiment, the spill tray 12 comprises an upper compartment 22 into which the window 13 opens and a lower compartment 23 which extends below the upper compartment 22. The lower compartment 23 and the upper compartment 22 are therefore stacked one above the other along the vertical axis. The upper compartment 22 and the lower compartment 23 are separated by a central wall 24 and are in fluid communication via an opening 25 formed in the central wall 24. The filter 26 can be mounted in the opening 25 in order to filter the dielectric fluid 4 flowing towards the lower compartment 23.

[0035] In order to facilitate the flow towards the lower compartment 23, the central wall 24 may be inclined relative to a horizontal plane, for example following a slope of between 1% and 5%, typically a slope of 2%. The central wall 24 is then inclined so that its lowest point corresponds to the part in which the opening is formed. In one embodiment, the opening is formed close to one of the side walls 21 (see [Fig.4]). Alternatively, the opening could be centered relative to the central wall 24, in which case the central wall 24 is substantially pyramidal.

[0036] In this embodiment, the pump 10 is connected to a suction orifice 32 formed in one of the side walls 21, 7 or in the bottom wall 20 of the discharge tank 12, at the level of the lower compartment 23. Preferably, the suction orifice 32 extends in a lower zone of one of the side walls 21, 7, and the bottom wall 20 of the discharge tank 12 is inclined towards the suction orifice 32, for example with a slope of the order of 1%. The dielectric fluid 4 is therefore already filtered by the filter 26 when it is sucked in by the pump 10. The pump 10 delivers the filtered dielectric fluid 4 and sends it to the heat exchanger 11, for example of the oil / water exchanger type of 50 kW to 100 kW in order to obtain a temperature difference of at least 13°C between the inlet and the outlet of the dielectric fluid 4, knowing that the maximum target operating temperature of the dielectric fluid 4 is 60°C.The temperature of the dielectric fluid 4 entering the heat exchanger 11 may be between 30°C and 45°C, and its outlet temperature may be between 45°C and 60°C (depending on the external weather conditions). The temperature of the cold water entering the heat exchanger 11 is preferably less than or equal to 40°C (30°C in winter) and the outlet temperature, after heat exchange with the dielectric fluid 4, may be of the order of 45°C to 55°C. Once cooled, the dielectric fluid 4 is discharged into the immersion tank 3, preferably through orifices formed near the bottom wall 5, typically in the bottom wall 5 or in the lower part of the side walls 6. In this way, the cooled dielectric fluid 4 rises naturally by convection along the computer devices 2, which it cools by heat transfer.The dielectric fluid 4 is therefore gradually heated by the computer devices 2 until it reaches the surface of the immersion tank 3 and overflows into the spill tank 12.

[0037] The volume of the lower compartment 23 is preferably greater than the volume of the upper compartment 22 so that it serves as a reservoir for the dielectric fluid 4.

[0038] In one embodiment, the cooling system comprises two cooling circuits each comprising a pump 10 and a heat exchanger 11, so as to ensure the cooling of the dielectric fluid 4, even in the event of failure of one of the components. In this embodiment, only one of the cooling circuits is operated at a time, the other cooling circuit being redundant.

[0039] The cooling circuit(s) are preferably placed outside the immersion tank 3 and the spill tank 12. For example, all or part of the cooling circuits may be placed in a technical compartment 27, which may adjoin the spill tank 12 or be at a distance from the spill tank 12. In the embodiment illustrated in FIGS. 2 to 4, the technical compartment 27 is contiguous with the immersion tank 3 and spill tank 12 and extends over the width and height of the tanks 3, 12. This technical compartment 27 comprises the two pumps 10, the two heat exchangers 11 and the pipes connecting the pumps 10 to the spill tank 12 and to the heat exchangers 11. This embodiment makes it possible to facilitate the maintenance of the immersion tank 3 and spill tank 12 by allowing easy access to the cooling circuit.

Claims

Claims

1. Installation (1) comprising: - an immersion tank (3) comprising retaining means (8) configured to receive computer devices (2) and a dielectric fluid (4), the retaining means (8) being positioned in the immersion tank (3) so that the computer devices (2) are immersed in the dielectric fluid (4); - a spill tank (12) placed next to the immersion tank (3), the spill tank (12) comprising dielectric fluid (4) and being separated from the immersion tank (3) by a partition wall (7);a window (13) having a lower edge (14) being formed in the partition wall (7) so as to put the immersion tank (3) and the spill tank (12) into fluid communication, a level of dielectric fluid (4) in the immersion tank (3) being higher than a level of dielectric fluid (4) in the spill tank (12) so that the dielectric fluid (4) pours through the window (13) into the spill tank (12) when its level reaches the lower edge (14) of the window (13).;

2. Installation (1) according to claim 1, further comprising a window adjustment device (13) configured to adjust the level of dielectric fluid (4) in the immersion tank (3).

3. Installation (1) according to one of claims 1 and 2, further comprising a system for cooling the dielectric fluid (4) comprising a pump (10) configured to suck fluid into the spill tank (12) and a heat exchanger (11) configured to cool the dielectric fluid (4) sucked by the pump (10).

4. Installation (1) according to one of claims 1 to 3, further comprising a filter (26) in the spill tank (12) configured to filter the dielectric fluid (4).

5. Installation (1) according to claim 4 taken in combination with claim 3, in which the spill tray (12) comprises a first compartment (22) into which the window (13) opens and a second compartment (23) connected to the pump (10), the filter (26) being positioned between the first compartment (22) and the second compartment (23).

6. Installation (1) according to claim 5, in which the first compartment (22) is positioned above the second compartment (23) such that the dielectric fluid (4) flows by gravity from the first compartment (22) to the second compartment (23), a wall (24) of the first compartment (22) being inclined relative to a horizontal plane and the filter (26) being positioned at a low point of the wall (24).

7. Installation (1) according to one of claims 1 to 6, comprising several windows (13) distributed over a length of the immersion tank (3).

8. Installation (1) according to one of claims 1 to 7 further comprising at least one computer device (2) immersed in the dielectric fluid (4) and mounted in the retaining means (8).

9. Installation (1) according to claim 8, further comprising at least one electrical cable comprising a terminal (28) electrically connected to the computing device (2) and a cable portion (29) extending from the terminal (28), the lower edge (14) of the window (13) being positioned relative to the retaining means (8) so that the terminal (28) is immersed in the dielectric fluid (4) while the cable portion (29) is at a distance from the dielectric fluid (4).

10. Data center comprising an installation (1) according to one of claims 1 to 9 and computer devices (2) mounted in the retaining means (8).

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