Systems and methods to reduce vapor losses of immersion cooling systems

Abstract

Losses of vapor of a two-phase immersion cooling fluid from an immersion cooling tank are reduced through the use of one or more air knives or air curtains generating a horizontally oriented flow(s) of air and / or vapor over and / or under an opening in a top of the tank, which contains a server at least partially immersed in the immersion cooling fluid in liquid form. The flow(s) of air or vapor inhibits ingress of air into, and / or egress of vapor out of, the tank. The one or more air knives or air curtains may include one above the opening, one below the opening, one above and one below the opening, two above the opening or two below the opening

Description

TITLE OF THE INVENTIONSYSTEMS AND METHODS TO REDUCE VAPOR LOSSES OF IMMERSION COOLING SYSTEMSFIELD OF THE INVENTION

[0001] The invention is directed to two-phase immersion cooling.BACKGROUND OF THE INVENTION

[0002] Two-phase immersion cooling (2-PIC) is one the most promising technologies for cooling data centers. 2-PIC can significantly reduce cooling energy use, increase IT equipment life and is capable of cooling high power chips in the excess of 1 kW.

[0003] In 2-PIC, the entire server is submerged in a dielectric fluid which boils when in contact with hot components with a surface temperature above the fluid saturation temperature. A water-cooled (or water / glycol) condenser located inside the tank condenses the vapor on the external surface of the tube while water / glycol - at a lower temperature than the saturation temperature of the dielectric fluid - circulates inside the tubes. Warm water, or water / glycol (WG), exiting the condenser would be typically cooled by an air-cooled chiller.

[0004] One of the main challenges with 2-PIC are vapor losses, which can increase operating costs due to need for top-off (replenishment). Vapor losses can occur, for example, when the tank lid is open for maintenance, primarily but not limited to, in the case of server maintenance in which one or more servers need to be pulled from the tank while the other servers are operating (practice known as “hot swap”). In addition, there are ergonomic issues with removing servers from the tank without mechanical assist due to weight of servers and height of the tank.

[0005] Those skilled in the art will recognize that there is a need for addressing the above-described shortcomings by significantly reducing vapor losses, such as during maintenance (when the tank lid is an open position), and eliminating ergonomic challenges.SUMMARY OF THE INVENTION

[0006] There is provided a system for reducing vapor losses from a two-phase immersion cooling tank, including: an electronic component whose operation generates heat; a two-phase immersion cooling tank comprising a housing with a floor, a top, and walls extending between therebetween; and at least one air flow device and / or at least one vapor flow device. The floor, top, and walls of the tank define a cooling space that contains an immersion cooling fluid in liquid phase and a headspace containing the immersion cooling fluid in vapor phase. The top includes an opening allowing egress of vapor phase immersion cooling fluid to the ambient atmosphere and a lid that is positionable between a closed position in which the lid covers the opening and seals the cooling space from the ambient atmosphere and an open position in which the lid does not cover the opening and thereby allows exposure of the cooling space to the ambient atmosphere. The electronic component is detachably secured to the tank, is at least partially immersed in the liquid phase, is disposed below the opening, and is raiseable out of the cooling space via the opening. If present, the at least one air flow device is disposed over the opening and is adapted and configured to generate a horizontally oriented flow of air over the opening to inhibit egress of the vapor phase out of the tank via the opening. If present, the at least one vapor flow device is disposed within the headspace that is adapted and configured to generate a horizontally oriented flow of the vapor phase under the opening to inhibit egress of the vapor phase out of the tank via the opening.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG 1 is a schematic of an air curtain.

[0008] FIG 2 is a schematic of another air curtain.

[0009] FIG 3 is a schematic of yet another air curtain.

[0010] FIG 4 is a schematic of an air knife.

[0011] FIG 5 is a schematic of another air knife.

[0012] FIG 6A is an elevation schematic view of an embodiment of the invention.

[0013] FIG 6B is an elevation schematic view of the embodiment of FIG 6A in which the lid is in the open position and the air flow devices have been activated.

[0014] FIG 6C is an elevation schematic view of an alternative embodiment based upon the embodiment of FIGS 6A-6C, in which an optional receiving air curtain and vapor recovery unit is included.

[0015] FIG 7 is a top plan schematic view of the embodiment of FIG 6A.

[0016] FIG 8 is a partial elevation schematic view of the embodiment of FI6 6B illustrating the airflow and vapor flow cancellation effect.

[0017] FIG 9A is an elevation schematic view of another embodiment of the invention.

[0018] FIG 9B is an elevation schematic view the embodiment of FIG 9A in which the lid is in the open position and the air knives have been activated.

[0019] FIG 10A is an elevation schematic view of another embodiment of the invention including a single air flow device disposed above the opening.

[0020] FIG 10B is an elevation schematic view the embodiment of FIG 9A in which the lid is in the open position and the airflow device has been activated.

[0021] FIG 11 A is an elevation schematic view of another embodiment of the invention including a single air flow device disposed below the opening.

[0022] FIG 11 B is an elevation schematic view of the embodiment of FIG 9A in which the lid is in the open position and the air flow device has been activated.DETAILED DESCRIPTION OF THE INVENTION

[0023] The inventors propose using an air curtain or pair of air curtains or air knife or pair of air knives to reduce to reduce vapor losses and / or disperse vapor escaping the tank. Examples of commercial air curtains and air knives are shown in FIGS 1-5.

[0024] While air curtains work with a blower, air knives typically use compressed air. Air knives are typically used to dry parts in manufacturing lines while air curtains are used in several applications to keep cold air in or out of an area or to keep contaminated ambient air from contaminating air within an enclosure. The aircurtains illustrated in FIGS 1 -3 are examples of air curtains used in front of doors separating indoor and outdoor spaces, and in refrigerated cabinets to keep cold air contained.

[0025] In contrast to air curtains which involve a relatively more turbulent flow of air and which are typically induced with a blower, air knives provide a much thinner and laminar air stream and are typically induced with compressed air. FIGS 4-5 illustrate commercial examples of air knives.

[0026] In the proposed invention shown below, an air knife or air curtain is used to create a flow of air just outside an immersion cooling tank or to create a flow of vapor just inside an immersion cooling tank.

[0027] Alternatively, in the proposed invention, a pair of air knives or a pair of air curtains is used to create both a flow of air just outside the tank and a flow of vapor just inside the tank. In this alternative, since the outer flow of air will pull air from above and the inner flow of vapor will pull vapor from below, and the two flows are parallel to one another, one flow will pull against the other flow in the area between the two flows. In this way, they would balance out each other and reduce air flow into the tank, and perhaps more importantly reduce vapor flow out of the tank. In other words, the two parallel flows create a type of barrier. The objective is to reduce vapor losses.

[0028] A first embodiment of the system for reducing vapor losses is shown in FIGS 6A-8. The immersion cooling tank 1 has a floor 3, a top (including a lid) 5, first and second opposed sides 7, 9, and opposed front and rear sides 11 , 13 defining a cooling space containing immersion cooling fluid in liquid form 15 and a condenser 17 disposed in a headspace 18 above the liquid immersion cooling fluid 15. A plurality of servers 19 is The lid is movable between an open position in which case the servers 19 may be accessed from outside the immersion cooling tank 1 via an opening in the top 5 and a closed position in which case access to the servers 19 from outside the immersion cooling tank 1 is prevented. The lid may be comprised of the entire top 5 or only a portion thereof.

[0029] The system includes an air flow device 20 disposed above the top 5 of the immersion cooling tank 1 and a vapor flow device 22 disposed below the top 5 but above the condenser 17. Each of the air flow device 20 and vapor flow device 22may be an air knife or an air curtain. While the air flow device 20 is fed with air, the vapor flow device is fed with immersion cooling fluid vapor from headspace 18 or immersion cooling fluid vapor and air trapped inside the headspace 18.

[0030] A plurality of servers 19 are at least partially immersed in the liquid immersion cooling fluid 15, each of which is arranged in parallel and which extends in a direction from the first side 7 to the second side 9. Alternatively, each may extend in a direction from the front side 11 to the rear side 13. In operation, when the servers 19 are operated, they generate heating. The generated heat causes the immersion cooling fluid to boil as heat is removed from the servers 19. A coolant inlet 35 directs cooled coolant 36 into the condenser 17 and a coolant outlet 37 directs heated coolant out of the condenser 17. The heated coolant 38 is cooled at a heat rejection unit (not illustrated) that is disposed in fluid communication between the outlet 37 and inlet 35. Cooled coolant fed to the condenser 17 via inlet 35 is cooled to a predetermined temperature by the heat rejection unit that is lower than the boiling point of the immersion cooling fluid.

[0031] As best seen in FIG 6B, in order to gain access to a server 19, such as when removal of the server 19 is desired or when in situ maintenance upon the server 19 is desired, the lid is moved to its open position. Before, simultaneous with, or after the lid being moved to its open position, the air flow device 20 and vapor flow device 22 are operated. The air flow device 20 is adapted and configured to generate a horizontally oriented flow of air 24 from the second side 9 to the first side 7 over the headspace 18 to inhibit egress of the immersion cooling vapor out of the tank 1 via the opening formed by the open lid. The vapor flow device 22 is adapted and configured to generate a horizontally oriented flow 26 of immersion cooling fluid vapor in the headspace 18 and similarly inhibit egress of the immersion cooling fluid vapor phase out of the tank 1 via the opening formed by the open lid. Since the flow of air 24 will entrain air from above and below flow of air 24 and the flow of vapor 26 will pull vapor from above and below the flow of vapor 26, and the two flows 24, 26 are parallel to one another, one of the flows 24, 26 will pull against the other of the flows 24, 26 in the area between the two flows 24, 26. Preferably, each of flows 24, 26 is laminar. In this way and as best shown by FIG 8, they balance out each other and reduce ingress of air into the tank, and more importantly, reduce egress ofimmersion cooling fluid vapor out of the tank 1. In other words, the two parallel flows 24, 26 create a type of barrier.

[0032] In an alternative embodiment based upon the embodiment of FIGS 6A-6B, as best shown in FIG 6C, opposite the airflow device 20 is an air receiving curtain 30 and a vapor recovery unit 32. The air receiving curtain comprises a vacuum pump which pulls air from flow 24. The vapor recovery unit 32 receives the pulled-in air, which may contain amounts of immersion cooling fluid vapor. The vapor recovery unit 32 produces a waste flow 34 of air deficient in immersion cooling fluid vapor, relative to the pulled-in air, and a return flow 36 enriched in immersion cooling fluid vapor. The waste flow 34 may be sent to an abatement unit, such as a thermal destruct unit, or simply vented to ambient. The return flow 36 is returned, in liquid and / or vapor form, back to the immersion tank or to a recovery tank external to the immersion tank. The particular way in which the pulled-in air is separated into flows 34, 36 is not limited. Preferably, the vapor recovery unit 32 comprises an adsorbent bed, for example activated carbon, or a cold trap.

[0033] A second embodiment of the system for reducing vapor losses, shown in FIGS 9A-9B, differs from the system of the first embodiment. Instead of an airflow device 20 disposed above the top 5, an additional vapor flow device 20’ is disposed below the opening formed by the lid in its open position. The additional vapor flow device 20’ is adapted and configured to generate a horizontally oriented flow 24’ of immersion cooling fluid vapor in the headspace 18 above the horizontally oriented flow 26 and its operation inhibits ingress of air into, and / or egress of immersion cooling fluid vapor out of, the immersion cooling tank 1 via the opening formed by the open lid. Each of the additional vapor flow device 20’ and vapor flow device 22 may be an air knife or an air curtain.

[0034] A third embodiment of the system for reducing vapor losses, shown in FIGS 10A-10B, differs from the system of the first embodiment in that it does not include the vapor flow device 22. Similar to the first embodiment, the air flow device 20 is disposed above the top 5 and is adapted and configured to generate a horizontally oriented flow of air 24 above the opening formed by the lid in the open position. Its operation inhibits ingress of air into, and / or egress of immersion cooling fluid vaporvapor out of, the immersion cooling tank 1 via the opening formed by the open lid. The air flow device 20 may be an air knife or an air curtain.

[0035] A fourth embodiment of the system for reducing vapor losses, shown in FIGS 11A-11B, differs from the system of the first embodiment in that it does not include the air flow device 20. However, similar to the first embodiment, the vapor flow device 22 is disposed below the top 5 and is adapted and configured to generate a horizontally oriented flow of vapor 26 in the headspace. Its operation inhibits ingress of air into, and / or egress of immersion cooling fluid vapor out of, the immersion cooling tank 1 via the opening formed by the open lid. The vapor flow device 22 may be an air knife or an air curtain.

[0036] Regardless of which embodiment is selected, the objective of the invention is to reduce the concentration of vapor immediately outside of the tank.

Claims

CLAIMSWhat is claimed is:

1. A system for reducing vapor losses from a two-phase immersion cooling tank, comprising: an electronic component whose operation generates heat; a two-phase immersion cooling tank comprising a housing with a floor, a top, and walls extending between therebetween that define a cooling space that contains an immersion cooling fluid in liquid phase and a headspace containing the immersion cooling fluid in vapor phase, the top including an opening allowing egress of vapor phase immersion cooling fluid to the ambient atmosphere and a lid that is positionable between a closed position in which the lid covers the opening and seals the cooling space from the ambient atmosphere and an open position in which the lid does not cover the opening and thereby allows exposure of the cooling space to the ambient atmosphere, wherein the electronic component is detachably secured to the tank, is at least partially immersed in the liquid phase, is disposed below the opening, and is raiseable out of the cooling space via the opening; and at least one airflow device disposed over the opening that is adapted and configured to generate a horizontally oriented flow of air over the opening to inhibit egress of the vapor phase out of the tank via the opening and / or at least one vapor flow device disposed within the headspace that is adapted and configured to generate a horizontally oriented flow of the vapor phase under the opening to inhibit egress of the vapor phase out of the tank via the opening.

2. The system of claim 1 , wherein said at least one airflow device and said at least one vapor flow device comprises one air flow device disposed above the opening.

3. The system of claim 2, further comprising: an air receiving curtain disposed above the opening and opposite the air flow device that comprises a vacuum pump which is adapted and configured to pull air from the horizontally oriented flow of air from the air flow device; a vapor recovery unit that is adapted andconfigured to receive the pulled-in air, which may contain amounts of immersion cooling fluid vapor, produce a waste flow of air deficient in immersion cooling fluid vapor relative to the pulled-in air, and a return flow enriched in immersion cooling fluid vapor, wherein the return flow is returned, in liquid and / or vapor form, back to the immersion tank or to a recovery tank external to the immersion tank.

4. The system of claim 1 , wherein said at least one air flow device and said at least one vapor flow device comprises one vapor flow device disposed below the opening.

5. The system of claim 1 , wherein said at least one airflow device and said at least one vapor flow device comprises one air flow device disposed above the opening and one vapor flow device disposed below the opening.

6. The system of claim 5, further comprising: an air receiving curtain disposed above the opening and opposite the air flow device that comprises a vacuum pump which is adapted and configured to pull air from the horizontally oriented flow of air from the air flow device; a vapor recovery unit that is adapted and configured to receive the pulled-in air, which may contain amounts of immersion cooling fluid vapor, produce a waste flow of air deficient in immersion cooling fluid vapor relative to the pulled-in air, and a return flow enriched in immersion cooling fluid vapor, wherein the return flow is returned, in liquid and / or vapor form, back to the immersion tank or to a recovery tank external to the immersion tank.

7. The system of claim 1 , wherein said at least one air flow device and said at least one vapor flow device comprises one vapor flow device disposed below the opening.

8. The system of claim 1 , wherein said at least one airflow device and said at least one vapor flow device comprises two air flow devices each of which is disposed above the opening and which are adapted and configured to generate flows of gases in parallel and opposite directions.

9. The system of claim 1 , wherein said at least one airflow device and said at least one vapor flow device comprises two vapor flow devices each of which isdisposed below the opening and which are adapted and configured to generate flows of gases in parallel and opposite directions.

10. The system of any one of claims 1 -9, wherein each of said at least one air device and each of said at least one vapor flow device is an air knife-type device.11 . The system of any one of claims 1-9, wherein each of said at least one air device and each of said at least one vapor flow device is an air curtain-type device.

12. A method for reducing vapor losses from a two-phase immersion cooling tank, comprising the steps of: an electronic component whose operation generates heat; a two-phase immersion cooling tank comprising a housing with a floor, a top, and walls extending between therebetween that define a cooling space that contains an immersion cooling fluid in liquid phase and a headspace containing the immersion cooling fluid in vapor phase, the top including an opening allowing egress of vapor phase immersion cooling fluid to the ambient atmosphere and a lid that is positionable between a closed position in which the lid covers the opening and seals the cooling space from the ambient atmosphere and an open position in which the lid does not cover the opening and thereby allows exposure of the cooling space to the ambient atmosphere, wherein the electronic component is detachably secured to the tank, is at least partially immersed in the liquid phase, is disposed below the opening, and is raiseable out of the cooling space via the opening; and at least one airflow device disposed over the opening that is adapted and configured to generate a horizontally oriented flow of air over the opening to inhibit egress of the vapor phase out of the tank via the opening and / or at least one vapor flow device disposed within the headspace that is adapted and configured to generate a horizontally oriented flow of the vapor phase under the opening to inhibit egress of the vapor phase out of the tank via the opening.

13. The method of claim 1 , wherein said at least one air flow device and said at least one vapor flow device comprises one air flow device disposed above the opening.

14. The method of claim 13, further comprising the steps of: pulling in air, from the flow of air generated by the air flow device, with an air receiving curtain disposed above the opening and opposite the air flow device that comprises a vacuum pump, wherein the pulled-in air contains amounts of immersion cooling fluid vapor; receiving the pulled-in air, from the air receiving curtain, into a vapor recovery unit; using the vapor recovery unit to produce a waste flow of air deficient in immersion cooling fluid vapor relative to the pulled-in air and a return flow enriched in immersion cooling fluid vapor; and returning the return flow, in liquid and / or vapor form, back to the immersion tank or to a recovery tank external to the immersion tank.

15. The method of claim 1 , wherein said at least one air flow device and said at least one vapor flow device comprises one vapor flow device disposed below the opening.

16. The method of claim 1 , wherein said at least one airflow device and said at least one vapor flow device comprises one air flow device disposed above the opening and one vapor flow device disposed below the opening.

17. The method of claim 16, further comprising the steps of: pulling in air, from the flow of air generated by the air flow device, with an air receiving curtain disposed above the opening and opposite the air flow device that comprises a vacuum pump, wherein the pulled-in air contains amounts of immersion cooling fluid vapor; receiving the pulled-in air, from the air receiving curtain, into a vapor recovery unit;using the vapor recovery unit to produce a waste flow of air deficient in immersion cooling fluid vapor relative to the pulled-in air and a return flow enriched in immersion cooling fluid vapor; and returning the return flow, in liquid and / or vapor form, back to the immersion tank or to a recovery tank external to the immersion tank.

18. The method of claim 1 , wherein said at least one air flow device and said at least one vapor flow device comprises two air flow devices each of which is disposed above the opening and which are adapted and configured to generate flows of gases in parallel and opposite directions.

19. The method of claim 1 , wherein said at least one air flow device and said at least one vapor flow device comprises two vapor flow devices each of which is disposed below the opening and which are adapted and configured to generate flows of gases in parallel and opposite directions.

20. The method of any one of claims 1-19, wherein each of said at least one air device and each of said at least one vapor flow device is an air knife-type device.21 . The method of any one of claims 1-20, wherein each of said at least one air device and each of said at least one vapor flow device is an air curtain-type device.

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