Systems and methods to reduce vapor losses of immersion cooling systems

Abstract

Losses of vapors of a two-phase immersion cooling tank are reduced by positioning a secondary enclosure on top of an immersion cooling tank containing an electronic component that is at least partially immersed in the immersion cooling fluid in liquid form. Bottom edges of the walls of the secondary enclosure surround an opening in a top of the tank that is creating by positioning a lid of the tank into an open position. In this manner, the secondary enclosure reduces or prevents egress of the vapors into the ambient atmosphere.

Description

TS0096-W001TITLE 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 is one the most promising technologies for cooling data centers. Two-phase immersion cooling 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 two-phase immersion cooling, 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 two-phase immersion cooling 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.TS0096-W001SUMMARY OF THE INVENTION

[0006] A system for reducing vapor losses from a two-phase immersion cooling tank is disclosed that comprises: a two-phase immersion cooling tank comprising a housing with a floor, a top, and walls extending between therebetween that define a cooling space, the tank top including an opening allowing exposure of the cooling space to the ambient atmosphere and a lid that is positionable between a closed position in which the lid covers the tank top opening and seals the cooling space from the ambient atmosphere and an open position in which the lid does not cover the tank top opening and thereby allows exposure of the cooling space to the ambient atmosphere; at least one server that is detachably secured to the tank and which is at least partially immersed in a two-phase immersion cooling fluid in liquid phase, a headspace containing the two-phase immersion cooling fluid in vapor phase, a selected one of the at least one server being positioned directly below the opening and being adapted and configured to be detached from the tank and raised out of the cooling space via the opening; and a secondary enclosure positionable over the tank top and comprising a top and walls extending downwardly therefrom, defining a maintenance space, wherein bottom edges of the secondary enclosure walls are adapted and configured to abut against the tank top and surround the opening to reduce egress of the vapor phase immersion cooling fluid into the ambient atmosphere via the opening.

[0007] A method for reducing vapor losses from a two-phase immersion cooling tank is disclosed that comprising the steps of: providing the above-disclosed system; positioning the enclosure over a selected one of the at least one server for maintenance thereof; opening the lid, thereby allowing access to the selected server by an operator; raising the selected server up out of the cooling space; and closing the lid, wherein bottom edges of the enclosure walls are allowed to abut against the tank top and surround the opening to reduce egress of the vapor phase immersion cooling fluid into the ambient atmosphere during said steps of opening the lid, raising the selected server, and closing the lid.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG 1 is a schematic of the system of the invention prior to placement over a selected server.TS0096-W001

[0009] FIG 2 is a schematic of the system of the invention after placement over a selected server.

[0010] FIG 3 is a schematic of the system of the invention after placement over a selected server and abutment of the bottom edges of the enclosure walls against the opening of the tank top.

[0011] FIG 4 is a schematic of the system of the invention of FIG 3 after the cable is lowered to the selected server by the hoist.

[0012] FIG 5 is a schematic of the system of the invention of FIG 4 after the selected server is raised into the maintenance space by the hoist.

[0013] FIG 6 is a schematic of the system of the invention of FIG 5 after the lid has been closed.DETAILED DESCRIPTION OF THE INVENTION

[0014] As seen in the FIGS, at least one server 1 is detachably secured within an immersion cooling tank 5 that comprises a housing with a floor 7, at top 9, and walls 11 extending therebetween to define a cooling space. The top 9 includes a lid 13 that is positionable between closed position in which the lid covers the top 9 opening and seals the cooling space from the ambient atmosphere and an open position in which the lid 13 does not cover the tank top 9 opening and thereby allows exposure of the cooling space to the ambient atmosphere.

[0015] The at least one server 1 , preferably a plurality of servers, is at least partially immersed in immersion cooling fluid, in liquid phase 15. Operation of the at least one server 1 generates heat and boiling of the immersion cooling fluid 15 at hot surfaces thereof. The resultant vapor is condensed at a condenser 17, disposed in a headspace 19 above the liquid phase 15, that is fed with a coolant fluid (e.g., water or water / glycol). In this manner, the servers may be maintained at a safe temperature. As seen in FIGS 3-5, a selected one of the at least one server 1 is positioned directly below the opening in the top 9 and each of the at least one server is adapted and configured to be detached from the tank 5 and raised out of the cooling space via the opening.TS0096-W001

[0016] In order to prevent or reduce emissions of immersion cooling fluid vapor into the environment during moments when the lid 13 is open, there is proposed the use of a secondary enclosure 21 . Enclosure 21 is disposed upon the tank top 9 and comprises a top 23 and walls 25 extending downwardly therefrom, defining a maintenance space 27. Bottom edges 29 of the secondary enclosure 21 walls are adapted and configured to abut against the tank top 9 and surround the opening to reduce emissions of the immersion cooling fluid vapor into the ambient atmosphere via the opening. In an embodiment, the bottom edges 29 are hermetically sealable to the tank top 9 to provide even greater protection. Preferably, the secondary enclosure is comprised of a rigid material and / or a flexible material.

[0017] The enclosure 21 may be moved over the tank 5 to position it directly over a selected one of the at least one server 1 with the use of an electric crane that comprises a hoist 31 traveling on a gantry trolley 33 suspended above the tank 5. The hoist 31 comprises a load-bearing cable 35 that extends through the secondary enclosure top 23 that terminates in at least one hook 37 that is disposed within the maintenance space 27. The hoist is operable to raise or lower the at least one hoist hook 37. While only a single hoist hook 37 is illustrated in the FIGS, one of ordinary skill will appreciate that two or even more hoist hooks 37 may be used for greater stability. The at least one hoist hook 37 is adapted and configured to be detachably secured to a selected one of the at least one server 1 so as to allow the selected server 1 to be raised out of the cooling space by operation of the hoist 31 via the cable 35 and at least one hook 37.

[0018] Typically, the at least one hoist hook 37 comprises at least a pair of hoist hooks 37 and each of the at least one server comprises a bracket that includes a associated pair of receptacles (not illustrated) that are adapted and configured to securely receive the associated pair of hoist hooks 37. The pair of hoist hooks 37 and brackets are adapted and configured to allow the selected server 1 to be raised out of the cooling space by the hoist 31 via the pair of hoist hooks 37 and bracket.

[0019] The enclosure 21 may include a plurality of suspension struts or cables 39 attached to the top 23 thereof at locations around a periphery thereof. Each of the plurality of suspension struts or cables 39 is adapted and configured to allow theTS0096-W001 enclosure 21 to be suspended via said plurality of suspension struts of cleats from a suitable structure.

[0020] In an embodiment, a mixture of air and immersion cooling vapor may be withdrawn from the maintenance through operation of a gas pump or fan 43 via an exhaust hose 41 which fluidly communicates in hermetic fashion between the gas pump or fan 43 and an opening 45 in the enclosure 21. Gas is supplied to the maintenance space 27 from a supply of gas 51 via a gas supply hose 53 fluidly communicates in hermetic fashion between a supply of gas 51 and an opening in the enclosure 21 . The supply of gas 51 comprises a source of compressed gas, nonlimiting types including an inert gas, air, or a mixture thereof, wherein the inert gas is preferably nitrogen. Optionally, the gas supply hose and / or the exhaust hose 41 ride with the gantry trolley.

[0021] The vapor recovery unit 49 is in downstream fluid communication from gas pump or fan 43 and receives the mixture withdrawn from the maintenance space 27. By the gas pump or fan 43. The vapor recovery unit separates the withdrawn mixture into a recovery stream that is enriched in the immersion cooling fluid vapor and deficient in air and a waste stream that is deficient in immersion cooling fluid vapor and enriched in air. In one variation, the vapor recovery unit 49 comprises a Peltier cooler or refrigeration unit that condenses amounts of immersion cooling fluid vapor in the withdrawn mixture, where the recovery stream is comprised of the condensed vapor and which is received into and stored by a recovery vessel 55 and the waste stream is vented. In another variation, the vapor recovery unit 49 comprises a gas centrifuge (which can take advantage of the large molecular weight difference between air and dielectric fluid vapor), a gas diffuser, or a gas separation membrane selective for the immersion cooling fluid over air gases or vice versa which separates the withdraw mixture into the recovery stream, in vapor phase, and the waste stream, also in vapor phase. The vapor phase recovery steam is received into and stored by the recovery vessel 55 and the waste stream is vented.

[0022] A controller may be provided that is adapted and configured to control a pressure of the maintenance space 27 to ambient or to a level vacuum that is insufficient to collapse the enclosure 21 . This is performed through controllingTS0096-W001 operation of the gas pump or fan 43 and regulating a flow of the gas from the gas supply 51 .

[0023] In order to allow access by an operator to a selected server 1 within the maintenance space 27, the enclosure 21 may be provided with a pair of glove ports 61 hemetically sealed to a corresponding pair of sleeved gloves (not illustrated) that are adapted and configured to allow an operator to insert their hands and arms into the sleeved gloves and manipulate the at least one server.

[0024] An embodiment of the method of the invention will now be described.

[0025] As seen in FIGS 1-2 movement of the hoist 31 upon the gantry trolley 33 by controlled by an operator to position the enclosure 21 over the at least one server 1 selected for maintenance. As seen in FIG 3, the hoist 31 is then operated to lower the enclosure 21 over the top, ensuring to seal the bottom edges 29 to the top 9 of the tank 5. Optionally, the suspension struts or cables 39 may be fastened to cleats formed on a support structure to allow the weight of the enclosure 21 to be borne by the support structure. The lid 13 is then placed in the open position. As seen in FIG 4, the hoist 31 lowers the cable 35 down to the selected server 1 and the at least one hook 35 is secured to the selected server 1 . As seen in FIG 5, the hoist raises the cable 35 up thereby raising the selected server 1 into the maintenance space 27. As seen in FIG 6, the lid 13 is closed. During the steps of opening the lid 13, raising the selected server 1 , and closing the lid 13, bottom edges 29 of the enclosure walls 25 are allowed to abut against the tank top 9 and surround the opening to reduce egress of the vapor phase immersion cooling fluid into the ambient atmosphere. In an embodiment, the bottom edges 29 are hermetically sealed against the tank top 9 to further reduce or prevent egress of the vapor phase immersion cooling fluid into the ambient atmosphere.

[0026] In an embodiment, after the lid 13 is closed, gas from the gas supply 49 is allowed to flow into the maintenance space 27 via the gas supply hose. Contemporaneous with the flow of gas, the gas pump or fan 43 is operated so as to initiate withdrawal of the mixture of air and immersion cooling fluid vapor from the headspace 19. The vapor recovery unit 49 is operated to separate the mixture withdrawn by the gas pump or fan 43 into the recovery stream which is enriched in the immersion cooling fluid vapor and deficient in air and the waste stream which isTS0096-W001 deficient in the immersion cooling fluid vapor and enriched in air. The recovery stream is received into and stored by the recovery vessel 55 and the waste stream is vented.

[0027] In an embodiment, a controller controls the pressure of the maintenance space 27 to ambient or to a level vacuum that is insufficient to collapse the enclosure 21. This is performed through controlling operation of the gas pump or fan 43 and regulating a flow of the gas from the gas supply 51.

[0028] In an embodiment, an operator inserts their hands and arms into the sleeved gloves and performs maintenance on the selected server 1 .

[0029] Some of the advantages of the invention include the following: a. It provides a solution for ergonomic issues experienced by operators. b. It provides a solution for operator exposure issues in the whole data center. c. Its footprint is vertical and doesn’t reduce server floor area density. d. Does not require vapor recovery at each immersion tank - so lid to tank can be closed while board is drying above e. Does not require custom-size structure to be placed on each tank, with concerns about safety (falling off) or placement, and cost f. One potential challenge of this invention is that it requires integration of gantry crane & hoist, vapor recovery system controls, vapor recovery equipment footprint nearby g. Potential options could be magnetic attachments to the tank

Claims

TS0096-W001CLAIMSWhat is claimed is:

1. A system for reducing vapor losses from a two-phase immersion cooling tank, comprising: a two-phase immersion cooling tank comprising a housing with a floor, a top, and walls extending between therebetween that define a cooling space, the tank top including an opening allowing exposure of the cooling space to the ambient atmosphere and a lid that is positionable between a closed position in which the lid covers the tank top opening and seals the cooling space from the ambient atmosphere and an open position in which the lid does not cover the tank top opening and thereby allows exposure of the cooling space to the ambient atmosphere; at least one server that is detachably secured to the tank and which is at least partially immersed in a two-phase immersion cooling fluid in liquid phase, a headspace containing the two-phase immersion cooling fluid in vapor phase, a selected one of the at least one server being positioned directly below the opening and being adapted and configured to be detached from the tank and raised out of the cooling space via the opening; and a secondary enclosure positionable over the tank top and comprising a top and walls extending downwardly therefrom, defining a maintenance space, wherein bottom edges of the secondary enclosure walls are adapted and configured to abut against the tank top and surround the opening to reduce egress of the vapor phase immersion cooling fluid into the ambient atmosphere via the opening.

2. The system of claim 1 , wherein the at least one server comprises a plurality of servers.

3. The system of any one of claims 1-2, further comprising an electric crane comprising a hoist traveling on a gantry trolley suspended above the tank, the hoist comprising a load-bearing cable extending through the secondary enclosure top that terminates in at least one hook that is disposed within the maintenance space, the hoist being operable to raise or lower the at least oneTS0096-W001 hoist hook, the at least hist hook being adapted and configured to be detachably secured to a selected one of the at least one server so as to allow the selected server to be raised out of the cooling space by operation of the hoist.

4. The system of claim 3, wherein the at least one hoist hook comprises at least a pair of hoist hooks, each of the at least one server comprises a bracket having a pair of receptacles adapted and configured to securely receive the pair of hoist hooks, and the pair of hoist hooks and brackets are adapted and configured to allow the selected server to be raised out of the cooling space by the hoist hooks via the bracket.

5. The system of any one of claims 3-4, wherein the hoist and the secondary enclosure are adapted and configured such that, when the hoist hook(s) is(are) raised or lowered by the hoist, the secondary enclosure is correspondingly raised or lowered.

6. The system of claim 5, wherein the hoist is detachably secured to the secondary enclosure.

7. The system of any one of claims 1-6, further comprising a plurality of suspension struts or cables attached to the top of the secondary enclosure at locations around a periphery thereof, each of the plurality of suspension struts or cables being adapted and configured to allow the secondary enclosure to be suspended via said plurality of suspension struts of cleats.

8. The system of any one of claims 1 to 7, further comprising: a gas supply, a gas supply hose fluidly communicating in hermetic fashion between the supply of gas and an opening in the secondary enclosure; a gas pump or fan; an exhaust hose fluidly communicating in hermetic fashion between the gas pump or fan and an opening in the secondary enclosure; a vapor recovery unit in downstream fluid communication between the gas pump or fan to receive a mixture of air and immersion cooling fluid vapor that is withdrawn by operation of the gas pump or fan via the exhaust hose.

9. The system of claim 8, further comprising a recovery vessel, wherein the vapor recovery unit is adapted and configured to separate the mixture into a wasteTS0096-W001 stream which is deficient in immersion cooling fluid vapor and enriched in air and a recovery stream which is enriched in immersion cooling vapor and deficient in air, the vapor recovery unit comprising a Peltier cooler or refrigeration system that is adapted and configured to condense amounts of immersion cooling fluid in the withdrawn mixture that are received and stored by the recovery vessel.

10. The system of claim 8, further comprising a recovery vessel, wherein: the vapor recovery unit is adapted and configured to separate the mixture into a waste stream which is deficient in immersion cooling fluid vapor and enriched in air and a recovery stream which is enriched in immersion cooling vapor and deficient in air; the vapor recovery unit comprises a gas centrifuge, gas diffuser, or gas separation membrane; and the recovery stream is received and stored by the recovery vessel.11 . The system of any one of claims 8-10, wherein the gas supply is a supply of an inert gas, air, or a mixture thereof, the inert gas preferably being nitrogen.

12. The system of any one of claims 8-11 , further comprising a controller that is adapted and configured to control a pressure within the maintenance space to ambient pressure or a vacuum level that is insufficient to collapse the secondary enclosure, the controller controlling the pressure within the maintenance space through controling operation of the gas pump or fan and regulating a flow of gas from the gas supply to the maintenance space.

13. The system of any one of claims 1-11 , wherein the bottom edges of the secondary enclosure walls and the tank top are adapted and configured to provide a seal preventing egress of the vapor phase immersion cooling fluid therethrough.

14. The system of any one of claims 1-13, wherein the secondary enclosure is comprised of a rigid material.

15. The system of any one of claims 1-14, wherein the secondary enclosure is comprised of a flexible material.

16. The system of any one of claims 1-15, wherein the secondary enclosure further comprises a pair of glove ports hemetically sealed to a corresponding pair ofTS0096-W001 gloves that are adapted and configured to allow an operator to insert their hands in the gloves and manipulate the at least one electronic component.

17. A method for reducing vapor losses from a two-phase immersion cooling tank, comprising the steps of: providing the system of claim 1 ; positioning the enclosure over a selected one of the at least one server for maintenance thereof; opening the lid, thereby allowing access to the selected server by an operator; raising the selected server up out of the cooling space; and closing the lid, wherein bottom edges of the enclosure walls are allowed to abut against the tank top and surround the opening to reduce egress of the vapor phase immersion cooling fluid into the ambient atmosphere during said steps of opening the lid, raising the selected server, and closing the lid.

18. The method of claim 17, wherein the at least one server comprises a plurality of servers.

19. The method of any one of claims 17-18, wherein said step of raising the selected server is performed by: providing an electric crane comprising a hoist traveling on a gantry trolley suspended above the tank, the hoist comprising a load-bearing cable extending through the secondary enclosure top that terminates in at least one hook that is disposed within the maintenance space; securing the at least one hoist hook to the selected server; and using the hoist to draw up the cable.

20. The method of any one of claims 17-19, further comprising the steps of: supplying gas to the maintenance supply from a gas supply via a gas supply which fluidly communicates in hermetic fashion between the gas supply and an opening in the secondary enclosure;TS0096-W001 separating the withdrawn mixture into a waste stream which is deficient in immersion cooling fluid vapor and enriched in air and a recovery stream which is enriched in immersion cooling vapor and deficient in air, the vapor recovery unit comprising a Peltier cooler or refrigeration system that is adapted and configured to condense amounts of immersion cooling fluid in the withdrawn mixture; and receiving and storing the recovery stream in a recovery vessel.21 . The method of any one of claims 17-19, further comprising the steps of: supplying gas to the maintenance supply from a gas supply via a gas supply which fluidly communicates in hermetic fashion between the gas supply and an opening in the secondary enclosure; separating the withdrawn mixture into a waste stream which is deficient in immersion cooling fluid vapor and enriched in air and a recovery stream which is enriched in immersion cooling vapor and deficient in air, the vapor recovery unit comprising a gas centrifuge, gas diffuser, or gas separation membrane; and receiving and storing the recovery stream in a recovery vessel.

22. The method of any one of claims 20-21 , wherein the gas supply is a supply of an inert gas, air, or a mixture thereof, the inert gas preferably being nitrogen.

23. The method of any one of claims 20-22, further comprising a controller that is adapted and configured to control a pressure within the maintenance space to ambient pressure or a vacuum level that is insufficient to collapse the secondary enclosure, the controller controlling the pressure within the maintenance space through controlling operation of the gas pump or fan and regulating a flow of the gas supplied to the maintenance space.

24. The method of any one of claims 17-23, wherein the bottom edges of the enclosure walls are sealed against the tank top and surround the opening to reduce egress of the vapor phase immersion cooling fluid into the ambient atmosphere during said steps of opening the lid, raising the selected server, and closing the lid.TS0096-W00125. The method of any one of claims 17-24, further comprising the steps of: allowing an operator to insert their hands and arms in a pair of sleeved gloves that which are hermetically sealed to a corresponding pair of glove ports formed in the secondary enclosure; and allowing the operator to perform maintenance upon the selected server in the maintenance space using the sleeved gloves.

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