Immersion cooling systems including direct immersion fluid cooling loop

Abstract

An immersion cooling system includes an immersion cooling tank defining a cavity sized and shaped for retaining a liquid volume of an immersion fluid and at least one electrical component to be immersed in the liquid volume of the immersion fluid, and for defining a vapor clearance above the liquid volume of the immersion fluid, and a direct immersion fluid cooling system operable in conjunction with the immersion cooling tank. The cooling system includes a vapor intake line positioned within the vapor clearance of the immersion cooling tank and operable to draw vapor phase of the immersion fluid therein, a heat exchanger positioned downstream from the vapor intake line and operable to reject heat from the immersion fluid, and a liquid line connected between the heat exchanger and the immersion tank for returning the immersion fluid from the heat exchanger to the immersion tank.

Description

TS0086-W001IMMERSION COOLING SYSTEMS INCLUDING DIRECT IMMERSION FLUID COOLING LOOPFIELD

[0001] The present disclosure related to the field of cooling systems, and in particular, immersion cooling.BACKGROUND

[0002] Two-phase immersion cooling is an emerging technology for cooling of electrical components, such as servers in data centers. In two-phase immersion cooling systems, the entire server is submerged and cooled by a liquid-phase dielectric fluid. The dielectric fluid boils when in contact with hot components with an operating surface temperature that is above the fluid saturation temperature. Vapor phase dielectric fluid emerges from a surface of the volume of the liquid-phase dielectric fluid. A water-cooled (or water / glycol-cooled) condenser is positioned above the liquid volume to contact the vapor phase dielectric fluid, extracting thermal energy therefrom to condense the dielectric fluid back into a liquid. The condensed dielectric fluid returns to the liquid volume, and the water or water / glycol mixture that is heated within the condenser is routed or channeled to another heat exchanger (e.g., an evaporator of a chiller system) where the water or water / glycol mixture is cooled and subsequently returned to the condenser.

[0003] Two-phase immersion cooling is advantageous since it is more effective than air or water-cooled (e.g., single phase) direct-to-chip technologies. Additionally, two-phase immersion cooling protects the electrical components (e.g., servers) being cooled from dust, moisture, and vibration. However, there is an ongoing need for improvements in two-phase immersion cooling technology to lower costs, reduce risks of electrical component damage, and make the cooling process more efficient.SUMMARY

[0004] In one aspect, an immersion cooling system includes an immersion cooling tank defining a cavity sized and shaped for retaining a liquid volume of an immersion fluid and at least one electrical component to be immersed in the liquid volume of the immersion fluid, and for defining a vapor clearance above the liquidTS0086-W001 volume of the immersion fluid, and a direct immersion fluid cooling system operable in conjunction with the immersion cooling tank. The cooling system includes a vapor intake line positioned at least partially within the vapor clearance of the immersion cooling tank, the vapor intake line being operable to draw vapor phase of the immersion fluid therein, a heat exchanger positioned downstream from the vapor intake line and operable to reject heat from the immersion fluid, a liquid line connected between the heat exchanger and the immersion tank for returning the immersion fluid from the heat exchanger to the immersion tank, and, optionally, a compressor connected between the vapor intake line and the heat exchanger for drawing a suction on the vapor intake line and pressurizing the immersion fluid upstream from the heat exchanger.

[0005] In some embodiments of the immersion cooling system of the foregoing aspect, the cooling system includes an expansion device positioned on the liquid line. In some embodiments, the cooling system includes a liquid receiver positioned between the heat exchanger and the expansion device. In some embodiments, the cooling system includes a first bypass circuit for bypassing the expansion device. In some embodiments, the first bypass circuit includes an isolation valve for selectively allowing the immersion fluid to flow through the first bypass circuit around the expansion device. In some embodiments, the first bypass circuit includes a pump operable to move the immersion fluid through the cooling system. In some embodiments, the cooling system includes the compressor and a second bypass circuit for bypassing the compressor. In some embodiments, the second bypass circuit includes a bypass valve for selectively allowing the immersion fluid to flow through the first bypass circuit around the compressor.

[0006] In some embodiments of the immersion cooling system of the foregoing aspect, the cooling system includes a heat recovery circuit for routing a portion of the immersion fluid around the heat exchanger and through a heat recovery heat exchanger. In some embodiments, the heat recovery heat exchanger is operable to utilize thermal energy from the immersion fluid for comfort heating or water heating. In some embodiments, the heat recovery heat exchanger is operable to utilize thermal energy from the immersion fluid for a boiler. In some embodiments, the heatTS0086-W001 recovery circuit includes a three-way valve for diverting the portion of the immersion fluid towards the heat recovery heat exchanger.

[0007] In some embodiments of the immersion cooling system of the foregoing aspect, the immersion cooling system includes at least two of said immersion cooling tank, and the cooling system includes at least two said vapor intake line, each one of the vapor intake lines positioned at least partially within the vapor clearance of a response one of the immersion cooling tanks. In some embodiments, the cooling system is connected to the immersion tanks in parallel. In some embodiments, the cooling system is connected to the immersion tanks in series.

[0008] In some embodiments of the immersion cooling system of the foregoing aspect, the heat exchanger is elevated relative to the vapor intake line to enable operating the cooling system in a thermosiphon mode.

[0009] In some embodiments of the immersion cooling system of the foregoing aspect, the cooling system further includes a flash tank positioned on the liquid line and operable to separate vapor-phase and liquid-phase of the immersion fluid therein.

[0010] In some embodiments of the immersion cooling system of the foregoing aspect, the cooling system includes a gas bypass line connected between the flash tank and the compressor for routing the vapor-phase of the immersion fluid from the flash tank towards the compressor. In some embodiments, the cooling system includes a control valve on the gas bypass line. In some embodiments, the liquid phase of the immersion fluid is routed from the flash tank towards the immersion tank.

[0011] In some embodiments of the immersion cooling system of the foregoing aspect, the immersion cooling system further includes a convective booster circuit operable to route the immersion fluid downstream from the heat exchanger into intimate thermal connection with the at least one electrical component via at least one heat sink thermally coupled to the at least one electrical component. In some embodiments, the convective booster circuit includes at least one expansion valve upstream from the at least one heat sink. In some embodiments, the convective booster circuit further comprises at least one pump upstream of the at least one heatTS0086-W001 sink. In some embodiments, the cooling system includes a liquid receiver positioned on the liquid line upstream from the convective booster circuit and downstream from the heat exchanger, and a liquid receiver bypass circuit for selectively routing condensed immersion fluid around the liquid receiver towards the convective booster circuit.

[0012] In some embodiments of the immersion cooling system of the foregoing aspect, the immersion fluid is a dielectric fluid.

[0013] In some embodiments of the immersion cooling system of the foregoing aspect, the heat exchanger of the cooling system is located in an outdoor environment. In some embodiments, the cooling system comprises a fan operable to force an outdoor air stream across the heat exchanger.

[0014] Another aspect is a method for operating an immersion cooling system. The method includes: immersing at least one electrical component in a liquid volume of an immersion fluid retained in an immersion cooling tank, a vapor clearance being defined above the liquid volume of the immersion fluid; transferring heat from the at least one electrical component to the immersion fluid such that a vapor phase of the immersion fluid emerges from a surface of the liquid volume into the vapor clearance; drawing the vapor phase of the immersion fluid into a vapor intake line of a direct immersion fluid cooling system, the vapor intake line being positioned at least partially within the vapor clearance; channeling the vapor phase of the immersion fluid from the vapor intake line to a heat exchanger of the cooling system, heat being rejected from the immersion fluid in the heat exchanger; and returning the immersion fluid from the heat exchanger to the immersion tank via a liquid line.

[0015] In some embodiments of the method of the foregoing aspect, the method includes pressurizing the immersion fluid downstream from the vapor intake line and upstream from the heat exchanger using a compressor. In some embodiments, the method includes expanding the immersion fluid downstream from the heat exchanger using an expansion device of the cooling system positioned on the liquid line. In some embodiments, the method includes collecting the immersion fluid in a liquid receiver of the cooling system positioned between the heat exchanger and the expansion device. In some embodiments, the method includes selectively bypassingTS0086-W001 the expansion device using a first bypass circuit. In some embodiments, the method includes selectively bypassing the expansion device by selectively actuating an isolation valve on the first bypass circuit. In some embodiments, the method includes channeling the immersion fluid through the cooling system using a pump positioned on the first bypass circuit. In some embodiments, the method includes selectively bypassing the compressor using a second bypass circuit. In some embodiments, the method includes selectively bypassing the compressor by selectively actuating a bypass valve positioned on the second bypass circuit.

[0016] In some embodiments of the method of the foregoing aspect, the method includes channeling at least a portion of the immersion fluid around the heat exchanger and through a heat recovery heat exchanger of a heat recovery circuit. In some embodiments, the method includes utilizing thermal energy rejected from the immersion fluid within the heat recovery heat exchanger for comfort heating or water heating. In some embodiments, the method includes utilizing thermal energy rejected from the immersion fluid within the heat recovery heat exchanger for a boiler. In some embodiments, the method includes diverting at least the portion of the immersion fluid towards the heat recovery heat exchanger using a three-way valve of the heat recovery circuit.

[0017] In some embodiments of the method of the foregoing aspect, the method includes: immersing another at least one electrical component in a liquid volume of an immersion fluid retained in at least one other immersion cooling tank, a vapor clearance being defined above the liquid volume of the immersion fluid in the at least one other immersion tank; in each at least one other immersion tank, transferring heat from the at least one electrical component to the immersion fluid such that a vapor phase of the immersion fluid emerges from a surface of the liquid volume into the vapor clearance of the immersion tank; in each at least one other immersion tank, drawing the vapor phase of the immersion fluid into another vapor intake line of the direct immersion fluid cooling system, the another vapor intake line being positioned at least partially within the vapor clearance of the immersion tank; channeling the vapor phase of the immersion fluid from the vapor intake lines to the heat exchanger of the cooling system; and returning the immersion fluid from the heat exchanger to the immersion tanks via the liquid line. In some embodiments, theTS0086-W001 cooling system is connected to the immersion tanks in parallel. In some embodiments, the cooling system is connected to the immersion tanks in series.

[0018] In some embodiments of the method of the foregoing aspect, the method includes operating the cooling system in a thermosiphon mode wherein the immersion fluid is channeled through the cooling system using a natural motive force induced by convection.

[0019] In some embodiments of the method of the foregoing aspect, the method includes separating vapor-phase and liquid-phase of the immersion fluid in a flash tank positioned on the liquid line. In some embodiments, the method includes channeling the vapor-phase of the immersion fluid from the flash tank towards the compressor via a gas bypass line connected between the flash tank and the compressor. In some embodiments, the method includes controlling flow of the vapor-phase of the immersion fluid using a control valve on the gas bypass line. In some embodiments, the method includes drawing the liquid-phase of the immersion fluid from the flash tank and channeling the liquid-phase of the immersion fluid towards the immersion tank.

[0020] In some embodiments of the method of the foregoing aspect, the method includes channeling the immersion fluid through a convective booster circuit downstream from the heat exchanger, into intimate thermal connection with the at least one electrical component via at least one heat sink thermally coupled to the at least one electrical component. In some embodiments, the method includes reducing a pressure of the immersion fluid in the convective booster circuit using at least one control valve upstream from the at least one heat sink. In some embodiments, the method includes channeling the immersion fluid through the convective booster circuit using at least one pump positioned upstream of the at least one heat sink. In some embodiments, the method includes collecting the immersion fluid in a liquid receiver of the cooling system positioned between the heat exchanger and the convective booster circuit. In some embodiments, the method includes selectively routing condensed immersion fluid from the heat exchangerTS0086-W001 around the liquid receiver towards the convective booster circuit via a liquid receiver bypass circuit.

[0021] In some embodiments of the method of the foregoing aspect, the immersion fluid is a dielectric fluid.

[0022] In some embodiments of the method of the foregoing aspect, the heat exchanger of the cooling system is located in an outdoor environment. In some embodiments, the method includes forcing an outdoor air stream across the heat exchanger using a fan.

[0023] Other features and advantages of the present invention will be apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various aspects and embodiments of the disclosure are described hereinbelow with references to the drawings, wherein:

[0025] FIG. 1 is a schematic view of an immersion cooling system that includes a conventional water / glycol cooling loop;

[0026] FIG. 2 is a schematic view of an electrical component of the immersion cooling system of FIG. 1 ;

[0027] FIG. 3 is a schematic view of first embodiment of an immersion cooling system that includes a direct immersion fluid cooling system in accordance with the present disclosure;

[0028] FIG. 4 is a schematic view of second embodiment of an immersion cooling system that includes a direct immersion fluid cooling system in accordance with the present disclosure;

[0029] FIG. 5 is a schematic view of third embodiment of an immersion cooling system that includes a direct immersion fluid cooling system in accordance with the present disclosure;TS0086-W001

[0030] FIG. 6 is a schematic view of fourth embodiment of an immersion cooling system that includes a direct immersion fluid cooling system in accordance with the present disclosure;

[0031] FIG. 7 is a schematic view of an electrical component of the immersion cooling system of FIG. 6; and

[0032] FIG. 8 is a cross-sectional view of a cold plate of the electrical component of FIG. 7.

[0033] Wherever possible and appropriate, the same reference numbers will be used throughout the drawings to represent the same parts.DETAILED DESCRIPTION

[0034] Large scale computer server systems can perform significant workloads and generate a large amount of heat during their operation. A significant portion of the heat is generated from their operation. Due in part to the amount of heat generated, these systems are typically mounted in stacked configurations with large internal cooling fans and heat dissipating fins. As the size and density of these systems increases the thermal challenges are even greater, and eventually outpace the ability for forced air systems.

[0035] Two-phase immersion cooling is an emerging cooling technology for the high-performance cooling market as applied to high performance server systems. It relies on the heat absorbed in the process of vaporizing a liquid immersion fluid to a gas. The fluids used in this application must meet certain requirements to be viable in use. For example, the normal boiling temperature of the fluid should be in the range between 30-75°C. Generally, this range accommodates maintaining the server components at a sufficiently cool temperature while allowing generated heat to be rejected effectively to an external heat sink. Alternatively, the operating temperature of the server, and the immersion cooling system could be raised or lowered, by using an enclosed system and raising or lowering the pressure within the system to raise or lower the boiling point of a given fluid.

[0036] Single phase immersion cooling has a long history in computer server cooling. There is no phase change in single phase immersion cooling. Instead, theTS0086-W001 liquid warms as it circulates through the computer server and or heat exchanger, and then is circulated with a pump to a heat exchanger for cooling prior to returning to the server, thus transferring heat away from the computer server. Fluids used for single phase immersion cooling typically have similar requirements as those for two-phase immersion cooling, except that the normal boiling temperatures are typically higher than 30-75°C.

[0037] Turning to the drawings, FIG. 1 illustrates an immersion cooling system 10 that includes an immersion tank 12 and a water / glycol fluid cooling loop 50 operably coupled to the immersion tank 12.

[0038] The immersion tank 12 defines a generally rectangular box shaped configuration having side surfaces 14 extending between a lower surface 16 and an opposed, upper surface 18. The upper surface 18 includes one or more openings, each opening being enclosed or covered by a tank lid 19. Where the upper surface 18 includes multiple openings, a single tank lid 19 or multiple tank lids 19 can be used to cover the openings. Although illustrated as defining a rectangular configuration, the immersion tank 12 can define any suitable configuration. In various embodiments, the immersion tank 12 has a circular, elliptical, racetrack, square, hexagonal, or other suitable configuration, and combinations thereof, without departing from the scope of the disclosure.

[0039] The immersion tank 12 includes an inner surface 20 defining a cavity 22. The cavity 22 extends longitudinally through the upper surface 18 towards the lower surface 16 and terminates at a bottom surface 24. In embodiments, the cavity 22 may extend through both the lower surface 16 and the upper surface 18, depending upon the design needs of the immersion cooling system 10.

[0040] The cavity 22 is sized and shaped to retain a fluid 26, also referred to as an immersion fluid, which in embodiments, is a dielectric immersion fluid or another suitable immersion fluid for use with an immersion cooling system. Examples of suitable immersion fluids used as the fluid 26 include, without limitation, FK- 5-1-12 (perfluoro(2-methyl-3-pentanone)), HFE-7100 (methoxy-nonafluorobutane), FC- 3284, FC-72, HT-55, HFO-153-10mczz(E), HFO-153-10mzzy(E), etc.TS0086-W001

[0041] In some embodiments, the composition of the fluid 26 includes one or more fluorinated compounds. In some embodiments, the fluid 26 includes one or more compounds including both fluorine and chlorine. In some embodiments, the fluid 26 includes one or more hydrofluorinated olefins. The fluid 26 can be selected to exhibit a dielectric constant, volume resistivity, dielectric strength, and / or loss tangent (e.g., dissipation factor) suitable for direct contact with electrical components. In this manner, materials exhibiting a low dielectric constant, low loss tangent or dissipation factor, high volume resistivity, and / or large dielectric strength provide increased electrical insulation, and in some instances, reduced signal loss. In embodiments, the dielectric constant of the fluid 26 may be less than about 8 over the operational frequency range (which may go as high as 100 GHz). Suitable fluids 26 include compounds and mixtures having a dielectric constant over the operational frequency range (up to about 100 GHz) of less than 2.5, or less than 2.0, or less thanI .9. Other embodiments include compounds and mixtures having a dielectric constant about greater than 1.0 and less than 2.0 or about greater than 1.5 and less than 2.5. The dielectric constant can be measured using ASTM D924, which provides a procedure for making referee tests at a commercial frequency of between 45 to 65 Hz. Suitable test methods for measuring the dielectric constant are also described in U.S. Patent No. 11 ,765,859, issued September 19, 2023, the disclosure of which is incorporated by reference in its entirety. For example, U.S. Patent No.I I,765,859 describes a method for measuring dielectric constant for high frequencies up to 67GHz. In embodiments, the fluid 26 may be selected based upon properties such as being non-flammable or presenting no flash point. Standards such as ASTM D56, D1310, D92, D93 and E681 can be used to assess flammability.

[0042] The fluid 26 (e.g., the dielectric immersion fluids) of the immersion cooling system 10 are selected to be in the liquid state over the operational temperature range of the immersion cooling system 10. In some embodiments, the operational temperature is at least 25°C, at least 30°C, at least 40°C, at least 50°C, at least 60°C, less than 100°C, less than 90°C, less than 80°C, less than 70°C, and combinations thereof.

[0043] One or more electrical components 28 are selectively supported within the cavity 22. In one cavity 22, there can be multiple (e.g., two or more, ten or more, orTS0086-W001 dozens) of electrical components 28 supported therein. The electrical components 28 are supported in the cavity 22 using any suitable method, such as fasteners, adhesives, friction or interference fit, etc. and oriented in any suitable direction. In the illustrated embodiment, the electrical components 28 are selectively supported within the cavity 22 in a vertical orientation. The electrical components 28 are also disposed in spaced apart relation in a direction that is transverse to the vertical orientation. In this manner, the fluid 26 is permitted to flow between and immerse each of the one or more electrical components 28. The electrical components 28 can have any orientation and spacing that enables the immersion cooling system 10 to function as described. The electrical components 28 are wholly submerged in the fluid 26 in the illustrated embodiment. Additionally or alternatively, any one or more of the electrical components 28 can be partially or wholly submerged in the fluid 26 depending upon the design needs of the immersion cooling system 10. The electrical components 28 include any electrical component suitable for immersion cooling. In some embodiments, each of the electrical components 28 is independently selected from an energy storage device, a computer chip, a motherboard, a server, a processor, a microprocessor, etc., and combinations thereof. In one non-limiting embodiment, the electrical components 28 form part of a data center.

[0044] Continuing with FIG. 1 and with additional reference to FIG. 2, in the illustrated embodiment, the electrical components 28 each include a substrate 30, upon which a chip 32 is operably supported. In the illustrated embodiment, each electrical component 28 of the one or more electrical components 28 is substantially similar to each other electrical component 28, and therefore, only one electrical component 28 will be described in detail hereinbelow for conciseness. The chip 32 is in thermal communication with, and operably coupled to, the substrate 30 using any suitable means, such as thermal paste, welding, adhesives, etc. to enable the substrate 30 to act as a heat sink and absorb and / or release thermal energy generated by the chip 32. Additionally, in the illustrated embodiment, a cold plate 34 is operably coupled to the chip 32 and disposed in a manner in which the chip 32 is interposed between the substrate 30 and the cold plate 34. The cold plate is in thermal communication with, and operably coupled to, the chip 32 using any suitable means, such as thermal paste, welding, adhesives, etc. to enable the cold plate 34TS0086-W001 to act as a heat sink and absorb and / or release thermal energy generated by the chip 32.

[0045] The substrate 30, the chip 32, and the cold plate 34 cooperate to absorb and spread thermal energy generated by the chip 32 over a greater mass and surface area. When immersed in the fluid 26, the wetted area, or surface area, of the electrical component 28 is greater than if the chip 32 is immersed within the fluid 26 on its own or if coupled to the substrate 30 and immersed within the fluid 26. In this manner, the increased wetted area of the electrical component 28 enables a greater amount of thermal energy to transfer from the electrical component 28 to the fluid 26 and enable the electrical component 28 to maintain a more even heat distribution during steady state conditions and / or spikes in thermal energy generated due to the load applied to the chip 32.

[0046] In operation, stagnant fluid 26 boils when in contact with the electrical components 28, which when under load or steady state operating conditions, may have a surface temperature that is above a fluid saturation temperature of the fluid 26. The boiling fluid 26, and resultant vapor, becomes less dense than the surrounding fluid 26, which causes the boiling fluid 26 to rise or otherwise flow towards the upper surface 18 of the immersion tank 12. This natural convection is a natural phenomenon that effectuates movement (e.g., circulation) of the fluid 26 within the immersion tank 12 without the aid of a pump or other mechanical fluid transfer device. Additionally or alternatively, a pump or other mechanical fluid transfer device can be included to effectuate movement (e.g., circulation) of the fluid 26 within the immersion tank 12. In such examples, the immersion tank 12 may utilize forced convective boiling of the fluid 26, as described in U.S. Provisional Patent App. No. XX / XXX.XXX, filed XXXX XX, 2024, titled “TWO-PHASE IMMERSION COOLING WITH CONVECTIVE BOOSTER,” Docket No. FL-2142, the disclosure of which is incorporated by reference in its entirety.

[0047] The vapor (indicated at 38) resulting from the fluid 26 boiling emerges from the fluid 26 in a portion of the cavity 22 between a surface of the fluid 36 and the upper surface 18 (enclosed by the tank lid 19) of the immersion tank 12. This portion of the cavity can be referred to as a vapor clearance 40. The fluid 26 may mix with vapor and / or other gases present in the cavity 22 forming such that non-condensableTS0086-W001 gases, such as nitrogen and oxygen, are present in the vapor clearance 40. These non-condensable gases can be detrimental to boiling and condensation heat transfer. In embodiments, the immersion cooling system 10 may include a supplemental device (not shown) that at least partially removes or controls the level of non-condensable gases in the fluid 26.

[0048] The vapor 38, also referred to as the immersion fluid vapor 38, in the can include differing densities and temperatures dependent upon the proximity of the vapor 38 to the surface of the fluid 36. This density gradient or stratified vapor 38 may separate into two portions; a vapor rich mixture adjacent to the surface of the fluid 36 and an air rich mixture interposed between the vapor rich mixture and the upper surface 18 of the immersion tank 12.

[0049] Returning to FIG. 1, the vapor 38 is condensed or otherwise liquified using the fluid cooling loop 50 that is operably coupled to the immersion tank 12. In the example of FIG. 1 , the fluid cooling loop 50 circulates a cooling fluid that includes water or a water / glycol mixture. The fluid cooling loop 50 includes a condenser 52 disposed within the cavity 22, and more particularly the vapor clearance 40, and in thermal communication with the vapor 38. The condenser 52 includes any suitable condenser configured to condense gas and / or vapor and compatible with the fluid 26. One condenser 52 or multiple condensers 52 can be included depending upon the design needs of the immersion cooling system 10. The condenser 52 is wholly or partially immersed in the vapor 38 to enable the vapor 38 to contact or otherwise be in thermal communication with a majority or entirety of the outer surface area of the condenser 52. Any amount of the condenser 52 may be in thermal communication with the vapor 38.

[0050] The fluid cooling loop 50 includes a fluid cooler 54 in fluid communication with the condenser 52. The fluid cooler 54 transfers thermal energy from the cooling fluid exiting the condenser 52. The cooling fluid in the condenser 52 is at a lower temperature than the saturation temperature of the vapor 38 in the vapor clearance 40 such that the vapor 38 condenses on an external surface of the condenser while the cooling fluid (e.g., water or water / glycol) circulates inside the condenser 52 andTS0086-W001 exits as relatively warm cooling fluid. The warm cooling fluid is cooled by the fluid cooler 54.

[0051] The fluid cooler 54 includes any suitable heat exchanger or coil that facilitates transferring thermal energy from the cooling fluid within the fluid cooler 54. For example, the fluid cooler 54 is a dry cooler or an adiabatic cooler. In some embodiments, the fluid cooler 54 is used in combination or substituted with a chiller (e.g., an air cooled chiller) or a cooling tower. In some embodiments, the fluid cooling loop 50 includes any combination of two or more of a dry cooler, an adiabatic cooler, another suitable standalone heat exchanger for cooling the cooling fluid, a chiller (e.g., an air cooled chiller), and a cooling tower. In such embodiments, the cooling fluid can be cooled in parallel or in series using the combination of the two or more cooling components. For example, in FIG. 1, an optional cooling fluid heat exchanger or coil 60 is used in combination and operates in parallel with the fluid cooler 54. Reference made herein to the “fluid cooler 54” encompasses any of these variations and combinations.

[0052] The thermal energy released by the fluid cooling loop 50 may be recovered (e.g., using a heat recovery coil 62) and used for heating applications or for energy generation such as Rankine cycles. Additionally or alternatively, the thermal energy transferred from cooling fluid exiting the condenser 52 in the fluid cooling loop 50 can be released or rejected into the environment. As an example, the heat rejected by the cooling fluid can be rejected into the environment using the fluid cooler 54 (or chiller or cooling tower) and / or the optional fluid cooling heat exchanger or coil 60. In some embodiments, the heat rejected by the cooling fluid using the fluid cooler 54 (or a chiller or cooling tower) can be recovered using the optional heat recovery coil 62, and the heat rejected by the cooling fluid using the optional fluid cooling heat exchanger or coil 60 is released into the environment. In other embodiments, the optional fluid cooling heat exchanger or coil 60 is not included (or is idle) and all the heat rejected from the cooling fluid using the fluid cooler 54 (or a chiller or cooling tower) is recovered using the optional heat recovery coil 62.

[0053] The fluid cooling loop 50 also includes a pump 56 in fluid communication with the condenser 52 and the fluid cooler 54. In the illustrated example, the pump 56 is positioned between an outlet 52a of the condenser 52 and an inlet 54a of theTS0086-W001 fluid cooler 54. Additionally or alternatively, the pump 56 can be positioned at any suitable location on the fluid cooling loop 50. The pump 56 circulates the cooling fluid within the fluid cooling loop 50 through each of the condenser 52 and the fluid cooler 54. Cooled fluid within the condenser 52 absorbs thermal energy from the vapor 38 within the cavity 22 and causes the vapor 38 to cool and condense back into the liquid 26. The pump 56 transfers the cooling fluid exiting the condenser that has been heated by the vapor 38 to the fluid cooler 54 where the heated fluid within the fluid cooling loop 50 is cooled and returned to the condenser 52.

[0054] In embodiments, a temperature of the fluid of the fluid cooling loop 50 exiting the condenser 52 may be between about 35° C and 45° C and a temperature of the fluid of the fluid cooling loop 50 exiting the fluid cooler 54 may be between about 30° C and 40° C. In embodiments, the temperature of the fluid of the fluid cooling loop 50 exiting the condenser 52, and the temperature of the fluid of the cooling fluid loop 50 exiting the fluid cooler 54 may be between about 10°C and a predetermined temperature below (e.g., between 1°C to 10°C below, such as between 1° to 5°C below) the normal boiling temperature of the cooling fluid.

[0055] There are several disadvantages of using the fluid cooling loop 50 that includes water or a water / glycol mixture as the cooling fluid. First, there is a risk that the water or water / glycol mixture can leak into the cavity 22 and contaminate the fluid 26. Although the risk is relatively low, there is always risk of a condenser rupture or leak that could introduce the cooling fluid from the loop 50 into the fluid 26. Any such leak could cause severe damage to very costly servers. Second, the target change in temperature across the condenser 52 for the water or water / glycol cooling fluid is relatively low, such as between about 3 to 6°C, which requires the pump 56 to operate at significant pump flow rates and consequently, utilize a large amount of power. This increases costs and otherwise makes the cooling loop 50 more energy inefficient. Third, using water or water / glycol as the cooling fluid in the loop 50 generally results in lower energy efficiency for heat rejection and heat recovery. The presence of the water or water / glycol loop 50 and a chiller introduces an energy and / or heat transfer inefficiency that, depending on the operating conditions, can be significant for heat rejection or heat recovery. Fourth, the water or water / glycol loop increases the overall footprint and capital burden of the coolingTS0086-W001 loop 50 since it requires an additional heat exchanger. For example, when a chiller is used, the water or water / glycol cooling fluid must exchange heat within the condenser 52 and within a heat exchanger (e.g., evaporator) of the fluid cooler 54. Even without the chiller, the fluid cooling heat exchanger 60 must be included to cool the cooling fluid having been heated within the condenser 52.

[0056] Table 1 below summarizes the assumptions and the estimated performance of the immersion cooling system 10 that includes a chiller as the fluid cooler 54, under four different operating conditions: 1) Cooling mode with the chiller 54 operating at a condensing temperature of 50°C; 2) Heating mode with the chiller 54 operating to recover heat at a condensing temperature of 70°C to produce hot water, for instance, for hydronic system (comfort heating); 3) Heating mode with a chiller operating as a boiler at a condensing temperature of 120°C; and 4) Fluid cooler mode (the water or water / glycol, WG, cooling fluid is directly pumped to the optional fluid cooling heat exchanger 60 with the chiller 54 off), possible when outside ambient temps are below about 34°C-30°C.TS0086-W001TABLE 1. ASSUMPTIONS AND THE ESTIMATED PERFORMANCE OF THE IMMERSION COOLING SYSTEM 10 (FIG. 1) UNDER FOUR DIFFERENT OPERATING CONDITIONSTS0086-W001

[0057] pPUE - 1 can be calculated according to Eq. 1 below:

[0058] Turning now to FIGS. 3-6, embodiments of the present disclosure address the limitations and disadvantages associated with the use of fluid coolers 54 and chillers using a direct immersion fluid cooling loop (or direct immersion fluid heat rejection loop) for the immersion fluid vapor 38. The direct immersion fluid cooling loop includes a vapor intake line that draws the immersion fluid vapor into a vapor compression circuit such that the immersion fluid vapor 38 can be condensed external to the immersion tank 12 and subsequently returned to the immersion tank 12 as a condensed liquid, eliminating the need for an additional cooling loop 50. The use of a direct immersion fluid cooling loop in conjunction with the immersion tank 12 also eliminates the risk of water or a water / glycol mixture leaking into the tank and damaging the electrical components 28. As described below, depending on ambient temperatures, the direct immersion fluid cooling loop can also facilitate moving the vapor immersion fluid to an outside heat exchanger, where it is condensed, using natural convective forces, when outside conditions allow, rather than a compressor, pump, or other mechanical movement device, thus facilitating more cost-effective and energy-efficient operation.

[0059] In the embodiments of FIGS. 3-6, the immersion tank 12 includes the elements and components described above with reference to FIGS. 1 and 2, unless expressly stated otherwise or the context clearly indicates otherwise. For brevity and ease of illustration, only some of the elements and components are indicated using reference numerals in FIGS. 3-6, with like reference numerals indicating like elements and components. The elements and components of the embodiments described with reference to FIGS. 3-6 can be combined in any suitable combination. Accordingly, any feature or element described with reference to one of the embodiments of FIGS. 3-6 that is not described with reference to another one of the embodiments of FIGS. 3-6 is not to be interpreted as limiting in any sense, and suchTS0086-W001 element and feature can be included in such other embodiment unless expressly stated otherwise or the context clearly indicates otherwise.

[0060] FIG. 3 illustrates a first embodiment of an immersion cooling system 100 that includes the immersion tank 12 and a direct immersion fluid cooling system 102 operably coupled to the immersion tank 12. For brevity, the direct immersion fluid cooling system 102 is also referred to as a direct cooling system or a “cooling system”. The cooling system 102 operates to circulate the immersion fluid, which enters the cooling system as immersion fluid vapor 38, through a vapor compression loop 104, in which the immersion fluid undergoes phase changes to enable the immersion fluid to reject thermal energy along the loop 104 and condense into the liquid immersion fluid 26.

[0061] Phase change of the immersion fluid in the vapor compression loop 104 is facilitated using various components of the cooling system 102 positioned on the loop 104. In the embodiment of FIG. 3, the cooling system 102 includes a compressor 106, a condenser 108, an expansion device 110 (e.g., an expansion valve), and a vapor intake line 112. The compressor 106 includes any suitable compressor that facilitates pressurizing the immersion fluid. The compressor 106 suitably operates without a lubricant or oil, which could otherwise contaminate the immersion fluid in the loop 104 and enter into the immersion tank 12. In some embodiments, the compressor 106 is an oil-free centrifugal compressor such as one available from Danfoss Turbocor (Tallahassee, FL). The compressor 106 is positioned on the loop 104 between the vapor intake line 112 and the condenser 108. The expansion device 110 is positioned between the condenser 108 and a liquid immersion fluid line 122 which returns the condensed immersion fluid to the immersion tank 12. The liquid immersion fluid line 122 is also referred to as a liquid line 122. The vapor intake line 112 includes one or multiple intake lines (e.g., perforated tubes or another suitable conduit with inlets that allow the immersion fluid vapor 38 to be drawn therein). The condenser 108 includes any suitable heat exchanger design, such as coils, concentric tubes, shell and tube, microchannels, etc. The condenser 108 can include one or multiple heat exchangers. The condenser 108 is also referred to as a heat exchanger 108 of the cooling system 102. In some embodiments, the condenser 108 is located outdoors or in anotherTS0086-W001 suitable environment that enables transferring thermal energy from the immersion fluid into an ambient air stream. Alternatively, the condenser 108 can transfer thermal energy between the immersion fluid in the loop 104 and any other fluid suitable for rejecting thermal energy into. For example, the condenser 108 can be water cooled.

[0062] The vapor intake line 112 is at least partially positioned in the immersion tank 12, and is wholly or partially positioned within the vapor clearance 40 of the immersion tank 12 to enable the immersion fluid vapor 38 to contact a majority or entirety of the outer surface area of the vapor intake line 112 and be drawn therein through inlets (e.g., holes, perforations, openings, etc.). Any amount of the vapor intake line 112 may be positioned in the vapor clearance 40. Suitable positions of the vapor intake line 112 include those described above for the condenser 52 with reference to FIG. 1.

[0063] In the example embodiment of FIG. 3, the condenser 108 transfers heat between immersion fluid in the vapor compression loop 104 and an ambient or environment fluid (e.g., outside air). For example, the condenser 108 includes a fan 114 that forces air across the condenser 108, whereby thermal energy is extracted from the immersion fluid in the condenser 108 and transferred to the air.Alternatively, the condenser 108 can transfer thermal energy between the immersion fluid in the vapor compression loop 104 and any other fluid suitable for rejecting thermal energy into.

[0064] In one example operation of the cooling system 102, suction is drawn on the vapor intake line 112 via the compressor 106, such that the immersion fluid vapor 38 is drawn from the clearance 40 into the vapor intake line 112. The immersion fluid vapor 38 flows as a low pressure gas from the vapor intake line 112 to the compressor 106 through a low pressure line 116. The compressor 106 compresses the low pressure immersion fluid at this stage, raising the temperature and pressure of the immersion fluid. The compressed, high temperature immersion fluid exiting the compressor 106 is channeled via a line 118 towards and passes through the condenser 108, where thermal energy is rejected into the outside air being forced across the condenser 108 via the fan 114. At this stage, the immersion fluid is condensed to a compressed, liquid. The compressed, condensed immersionTS0086-W001 fluid exiting the condenser 108 is channeled via a line 120 towards and passes through the expansion device 110 that reduces the pressure of the condensed immersion fluid. The immersion fluid exiting the expansion device 110 is low pressure liquid and is channeled via the liquid line 122 back towards and exits into the immersion tank 12. Meanwhile, immersion fluid vapor 38 in the immersion tank 12 continues to be drawn into the vapor intake line 112 and flows towards the compressor 106 via the line 116, where the immersion fluid is again compressed and the process repeats.

[0065] In the example embodiment of FIG. 3, the cooling system 102 includes additional components that provide greater versatility and flexibility with respect to operating modes of the cooling system 102 for condensing the vapor 38 in the immersion tank 12. For example, the cooling system 102 includes a liquid receiver 124 positioned on the line 120 for collecting condensed immersion fluid exiting the condenser 108, a first bypass circuit 126 positioned downstream from the liquid receiver 124, a second bypass circuit 128 positioned downstream from the vapor intake line 112, and / or a heat recovery circuit 130 positioned downstream from the compressor 106. A purge unit 125 can be connected to the liquid receiver 124 to remove or eliminate air from the immersion fluid within the liquid receiver 124. Any one or more of these additional components can be included independent of the other additional components.

[0066] The first bypass circuit 126 is positioned for routing, in part or in whole, the immersion fluid from the line 120 around the expansion device 110, and back towards immersion tank 12 via the line 122. The first bypass circuit 126 includes a pump 132 or other mechanical fluid transfer device, and an isolation valve 134 positioned relative to the pump 132. One or more isolation valves 134 can be included, and can be selectively positioned upstream or downstream from the pump 132. In the illustrated example, the isolation valve 134 is positioned downstream from the pump 132. In some examples, the isolation valve 134 can be a three-way valve positioned upstream from the pump 132 and the expansion device 110, at a junction between the first bypass circuit 126 and the line 122.

[0067] The second bypass circuit 128 is positioned for routing, in part or in whole, the immersion fluid from the line 116 around the compressor 106, and back towardsTS0086-W001 the condenser 108 via the line 118. The second bypass circuit 128 includes a bypass valve 136 that can be selectively actuated to allow the immersion fluid to flow through the second bypass circuit 128, around the compressor 106.

[0068] The heat recovery circuit 130 is positioned downstream from the compressor 106 and the second bypass circuit 128. The heat recovery circuit 130 includes a three-way valve 138 and a heat recovery heat exchanger 140 positioned downstream from the three-way valve 138. The three-way valve 138 can be selectively actuated to allow the immersion fluid in the line 118 to flow through the heat recovery circuit 130, where it passes through the heat recovery heat exchanger 140. The heat recovery heat exchanger 140 extracts thermal energy from the immersion fluid for use in heating applications, energy generation, or any suitable application that can benefit from the thermal energy rejected from the immersion fluid. The heat recovery heat exchanger 140 can have any suitable heat exchanger configuration, such as those described above for the condenser 108.

[0069] Example operating modes of the cooling system 102 will now be described. The operating modes of the cooling system 102 are not limited to the operating modes described herein, and the cooling system 102 can be operated in any suitable mode without departing from the scope of the present disclosure.

[0070] In an example cooling mode of the cooling system 102, which is similar to the example operation of the cooling system 102 described above, both the bypass valve 128 and the isolation valve 126 are closed, thus restricting or limiting flow of the immersion fluid through the bypass circuits 126, 128. The compressor 106 pressurizes the low pressure immersion fluid flowing from the vapor intake line 112 via the line 116, and the compressed immersion fluid is routed or channeled to the condenser 108 where the immersion fluid condenses. The condensed immersion fluid is then routed via the line 120 towards the liquid receiver 124, where the liquid immersion fluid is collected upstream from the expansion device 110.

[0071] In an example heating mode of the cooling system 102, the three-way valve 138 is actuated to divert the immersion fluid exiting the compressor 106, in whole or in part, to flow into the heat recovery circuit 130 and pass through the heat recovery heat exchanger 140 (e.g., a heat recovery coil). The compressor 106 canTS0086-W001 also be controlled to adjust a pressure of the immersion fluid in the heating mode, which varies the condensing temperature of the immersion fluid and the amount of thermal energy transferred via the heat recovery heat exchanger 140. For example, the condensing temperature of the immersion fluid in the heat recovery circuit 130 could be varied (increased or decreased), depending on the type of heat reuse application for the thermal energy extracted from the immersion fluid. For example, the thermal energy extracted from the immersion fluid via the heat recovery heat exchanger 140 in some embodiments is used for comfort heating or water heating. In some embodiments, the thermal energy extracted from the immersion fluid via the heat recovery heat exchanger 140 is used for a boiler. In some embodiments, head pressure control is applied to the compressor to control the condensing pressure of the immersion fluid in the cooling system 102.

[0072] In an example “compressor free” mode of the cooling system 102, the pump 132 on the first bypass circuit 126 is used to circulate the immersion fluid through loop 104 without operating the compressor 106. In this mode, the isolation valve 134 is open to enable the immersion fluid to flow through the first bypass circuit 126 and the bypass valve 136 is also opened to allow the immersion fluid to bypass the compressor 106 via the second bypass circuit 128. The cooling system 102 can be operated in the compressor free mode when outside ambient conditions allow (e.g., when the ambient temperature is cold enough to allow condensing the immersion fluid at lower pressure). This enables the cooling system 102 to be operated in a more energy efficient manner since less power is required to move the immersion fluid using the pump 132 than is required to pressurize the immersion fluid using the compressor 106.

[0073] Another example compressor free mode of the cooling system 102 includes a thermosiphon mode in which the immersion fluid is circulated through the vapor compression loop 104 using natural convection rather than by mechanical force. In such an example, both the compressor 106 and the pump 132 are idle. To enable the thermosiphon mode, the condenser 108 is elevated relative to the vapor intake line 112, and gravity and the density differential between the vapor 38 in the vapor intake line 112 and condensed immersion fluid in the condenser promote circulation of the immersion fluid through the loop 104. The cooling system 102 canTS0086-W001 be operated in the thermosiphon mode when outside ambient conditions allow (e.g., when the ambient temperature is cold enough to allow condensing the immersion fluid at lower pressure).

[0074] Table 2 below shows the performance of an example immersion cooling system, such as the immersion cooling system 100, that implements a cooling system, such as the cooling system 102, in a cooling mode, with the compressor 106 in operation and both the isolation valve 134 and the bypass valve 136 closed. Due to the absence of a water or water / glycol loop, the immersion cooling system can operate at a higher evaporating temperature which helps increase the cooling coefficient of performance (COP) by more than 3 times and, in fact, surprisingly decreases the “pPUE - 1” by about 58% compared to the immersion cooling system in “cooling mode with chiller” reported in Table 1 (at a “pPUE - 1” of 0.127). “p-PUE- 1” is defined by Eq. 1 above and represents the sum of the condenser fan power per unit of IT power, the pump power per unit of IT power and the inverse of the COP (which is equal to the compressor power divided by the IT power). The “IT power” refers to the power used by the application or electrical component(s), for example, the server(s). The lower the “pPUE-1”, the more energy efficient is the system.TS0086-W001TABLE 2. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A COOLING SYSTEM IN A COOLING MODE

[0075] Table 3 below shows the performance of an example immersion cooling system, such as the immersion cooling system 100, that implements a cooling system, such as the cooling system 102, in a heating mode for comfort heating, with the compressor 106 in operation and both the isolation valve 134 and the bypass valve 136 closed. In this example, the three-way 138 diverts 100% of the compressor flow to the heat recovery heat exchanger 140. Here the objective is to increase the heating COP, which represents the heating capacity produced per unit of compressor power. For the immersion cooling system implementing a WG cooling loop 50, the heating COP includes the power used by the pump 56 of the WG loop 50 (FIG. 1). Due to the absence of the WG loop 50, the immersion cooling system 100 is operable at a higher evaporating temperature which helps increase the heating COP by more than 80%, depending on the immersion fluid choice, compared to the immersion cooling system in the same mode of operation reported in Table 1TS0086-W001(heating COP of 7.6). When compared to a typical residential air-to-water heat pump, which operates with a seasonal efficiency of about 1.7 - 3.0 (See https: / / www.energystar.gov / partner_resources / products_partner_resources / brand- owner / eta-consumers / air-water-heat-pumps- 2019#:~:text=Compared%20to%20a%20typical%20gas,COP)%20of%201.7%20%2 D%203.0.), the immersion cooling system of this example is as much as about 4 to 8 times more energy efficient. In addition, the heating COP of the immersion cooling system of this example is independent of outside ambient temperature while for the air-to-water heat pump the energy efficiency drops with the decrease in outside ambient temperature.TABLE 3. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A COOLING SYSTEM IN A HEATING MODE FOR COMFORT HEATING

[0076] As described above, an immersion cooling system, such as the immersion cooling system 100, can implement a cooling system, such as the cooling system 102, operating in a heating mode to provide thermal energy to a boiler. The performanceTS0086-W001 results for such a system are shown in Table 4 below under heating mode for a boiler application. For this operating condition, a heating COP improvement of the immersion cooling system of the present disclosure versus the system that implements a WG loop (e.g. the loop 50 of FIG. 1) as reported in Table 1.TABLE 4. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A COOLING SYSTEM IN A HEATING MODE FOR A BOILER

[0077] Table 5 below shows the performance of an example immersion cooling system, such as the immersion cooling system 100, that implements a cooling system, such as the cooling system 102, in a compressor free mode, with a circulating pump 132 in operation, and the isolation valve 134 and the bypass valve 136 each open, when outside ambient conditions allow. For example, when the outside ambient temperature is about 7°C (Condenser TD) or more lower than the saturation temperature of the immersion fluid, or in this case at about 42°C (“Maximum Ambient Temp for Chiller off mode”), it is possible to have compressor free operation with a pump only. For the conventional system of FIG. 1 , compressor free operation would not be possible at temperatures above about 34°C (“MaximumTS0086-W001Ambient Temp for Chiller off mode”). This can represent a significant advantage for the system in accordance with the present disclosure, given that in most locations, for instance in the United States, outside ambient temps would rarely surpass 42°C. Due to reduction in pump power, and the latent heat of vaporization of the refrigerant immersion fluid, “pPUE-1” is reduced to about 0.03, or about 25% lower than the “pPUE-1” of the immersion cooling system with a WG loop reported in Table 1.TABLE 5. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A COOLING SYSTEM IN A COMPRESSOR FREE COOLING MODE

[0078] In some embodiments, the immersion cooling system 100 can include one or more pressure sensors 142 for monitoring pressure changes in the immersion tank 12 that can indicate whether a suitable amount of immersion fluid vapor 38 is available for operation of the cooling system 102. Specific controls could also be used to maintain adequate pressure inside the tank. In some embodiments, the internal tank pressure of the immersion tank 12 is controlled (e.g., varied) to above or below atmospheric pressure. By controlling the internal tank pressure of theTS0086-W001 immersion tank 12, the boiling point or saturation temperature of the immersion fluid 26 inside the tank 12 can be controlled (e.g., varied). For example, the internal tank pressure in some embodiments is controlled to raise the boiling point or saturation temperature of the immersion fluid 26 inside the tank 12 to increase efficiency of heat rejection. Additionally or alternatively, the internal tank pressure in some embodiments is controlled to lower the boiling point or saturation temperature of the immersion fluid 26 inside the tank 12 to improve cooling of the electrical components 28 (e.g., the chips 32), and / or reduce the operating temperature of the electrical components 28 (e.g., the chips 32).

[0079] In some embodiments, one or more filters are positioned on the vapor compression loop 104 to remove or eliminate contaminants that may enter into the immersion fluid across the loop. For example, one or more activated carbon based filters and / or filter driers can be installed on the liquid line 122 between the liquid receiver 124 and the immersion tank 12. The filters positioned on the vapor compression loop 104 operate to remove contaminants originating from the vapor compression loop 104 and limit or prevent such contaminants from entering into the tank 12.

[0080] In some embodiments, a suction-line / liquid-line (SL / LL) heat exchanger (not shown) is included in the vapor compression loop 104, depending on the refrigerant option. The SL / LL heat exchanger facilitates transferring thermal energy between the compressed, condensed immersion fluid in the line 120 and the uncompressed, gas immersion fluid in the line 116, which can help increase energy efficiency and performance of the compressor 106.

[0081] The cooling system 102 can provide a dedicated vapor compression loop 104 for condensing the immersion fluid vapor 38 drawn from a single immersion tank 12. Alternatively, the cooling system 102 can provide a vapor compression loop 104 that condenses the immersion fluid vapor 38 drawn from multiple immersion tanks 12. In such embodiments, the cooling system 102 can be connected to the immersion tanks 12 in series or in parallel. FIG. 4 illustrates a second embodiment of an immersion cooling system 200 that includes the cooling system 102 of FIG. 3 connected in parallel to two immersion tanks 12. The immersion tanks 12 and the cooling system 102 have the same elements and components as described aboveTS0086-W001 with reference to FIGS. 1 and 3, respectively. The cooling system 102 can be connected to any suitable number of immersion tanks 12, in series or in parallel, such as three, four, five, six, seven, eight, nine, ten, or more than ten immersion tanks 12.

[0082] In the example of FIG. 4, immersion fluid vapor 38 is drawn from each of the immersion tanks 12 via respective vapor intake lines 112a, 112b and flows towards the compressor 106 via the line 116. The immersion fluid vapor 38 that is drawn into a vapor intake line 112a from a first of the immersion tanks 12 flows through a line 204 towards the line 116, and the immersion fluid vapor 38 that is drawn into a vapor intake line 112b from a second of the immersion tanks 12 flows through a line 206 towards the line 116. The immersion fluid vapor 38 drawn from the immersion tanks 12 converges at a junction 208 of the lines 204, 206 and the line 116, and the mixed immersion fluid vapor 38 flows through the vapor compression loop 104 as described above. The immersion fluid that has exited the condenser 108 and / or the heat recovery circuit 130 and, optionally, is collected in the liquid receiver 124 and / or expanded using the expansion device 110, is routed to a cascading circuit 210 via the liquid line 122 where the immersion fluid is split into parallel streams at a split point 212. A first portion of the immersion fluid flows from the split point 212, in a first line 214 of the cascading circuit 202, to the first of the immersion tanks 12. A second portion of the immersion fluid flows from the split point 212, in a second line 216 of the cascading circuit 202, to the second of the immersion tanks 12.

[0083] FIG. 5 illustrates a third embodiment of an immersion cooling system 400 that includes the immersion tank 12 and a cooling system 402 operably coupled to the immersion tank 12. The cooling system 402 includes similar elements and components as the cooling system 102, with like elements and components indicated by like reference numerals. Additionally, in this embodiment, the cooling system 402 includes a gas bypass circuit 404 that includes a flash tank (or another gas-liquid separator) 406 positioned on the line 122 downstream from the expansion device 110. The flash tank 406 separates vapor-phase and liquid-phase immersion fluid therein. The vapor-phase immersion fluid is drawn from the flash tank 406 into a bypass line 410 of the gas bypass circuit 404, while the liquid-phase immersionTS0086-W001 fluid is drawn from the flash tank 406 into the line 122 and is routed towards the immersion tank 12. The bypass line 410 of the gas bypass circuit 404 is connected to the inlet of the compressor 106, such that the vapor-phase immersion fluid in the bypass line 410 is routed towards the compressor 106. A control valve 408 is positioned on the bypass line 410 for regulating flow of the vapor-phase immersion fluid being drawn from the flash tank 406 and / or entering the compressor 106 via the bypass line 410.

[0084] FIG. 6 illustrates a fourth embodiment of an immersion cooling system 500 that includes the immersion tank 12 and a cooling system 502 operably coupled to the immersion tank 12. The cooling system 502 of FIG. 6 includes similar elements and components as the cooling system 102, with like elements and components indicated by like reference numerals. Additionally, in this embodiment, the cooling system 502 includes a convective booster circuit 504 that enables forced convective boiling of the immersion fluid in the cooling system 502. Immersion tanks 12 that utilize forced convective boiling are described in U.S. Provisional Patent App. No. XX / XXX.XXX, filed XXXX XX, 2024, titled “TWO-PHASE IMMERSION COOLING WITH CONVECTIVE BOOSTER,” Docket No. FL2142-US01-PRV, the disclosure of which is incorporated by reference in its entirety.

[0085] With additional reference to FIGS. 7 and 8, to enable convective boiling of the immersion fluid in the immersion tank 12, each cold plate 34 of the immersion tank 12, supporting a chip 32, is formed from a porous or perforated material having a plurality of cavities, pores, etc. for receipt of the immersion fluid. In the illustrated embodiment, one or more channels 44 is defined longitudinally through the cold plate 34 for receipt of the immersion fluid via a line 506 of the convective booster circuit 504 that is connected to the line 122. Heat is transferred to working fluid within the cold plate 34, causing the working fluid to boil such that the working fluid is discharged as vaporized or otherwise relatively low pressure working fluid that emerges as immersion fluid vapor 38 in the vapor clearance 40 and is drawn into the vapor intake line 112 as described above. The cold plate 34 acts as a heat sink between the chip 32 and the immersion fluid, with the immersion fluid flowing through the channels 44 of the cold plate 34 to effectuate convective boiling of the immersion fluid and cooling of the chip 32. Although described as having channelsTS0086-W00144, the cold plate 34 alternatively employs any suitable type of heat transfer surface, such as microchannels, fins, pins, protuberances, metal foam, and combinations thereof. In some embodiments, the immersion fluid of the cooling system 502 is brought into heat transfer contact with the cold plate 34 using jet impingement or thin-film evaporation.

[0086] In some embodiments, the immersion fluid of the cooling system 502 moves through the convective booster circuit 504 via a natural motive force induced by convection. As the immersion fluid boils within the channels 44 of the cold plate 34, the boiling immersion fluid, and resultant vapor, becomes less dense than the immersion fluid entering the cold plate 34 via the line 506, which causes the boiling immersion fluid to rise and emerge from the surface 36 of the immersion fluid 26. Additionally and / or alternatively, for the immersion fluid entering one or more of the cold plates 34, a pump 512 (FIG. 7) can be provided to force the immersion fluid through the channels 44 of the cold plate 34, inducing convective boiling of the immersion fluid therein. The pump 512 can be any suitable fluid transfer device, and in embodiments, may be a small sump pump or a micro pump. Additionally and / or alternatively, suction from a pressure differential across the convective booster circuit 504 can moves the immersion fluid through the line 506 and the cold plate 34.

[0087] One or more expansion valves 510 are also positioned on the line 506 of the circuit 504. In the illustrated example, an expansion valve 510 is provided for each cold plate 34 (i.e. , is positioned on each branch of the line 506 supplying immersion fluid to the respective cold plate 34) to regulate a pressure of the immersion fluid through the respective cold plate 34. The expansion valves 510 suitably lower a pressure of the condensed immersion fluid to tank (evaporating) pressure. The expansion valves 510 can be manually actuatable, electronically actuatable, and combinations thereof. In some embodiments, the expansion valves 510 are controlled based on the temperature of the respective chip 32.

[0088] In the embodiment of FIG. 6, the immersion fluid in the line 122 (downstream from the condenser 108 and, optionally, the liquid receiver 124 and / or the first bypass circuit 126) is entirely routed into the line 506 of the convective booster circuit 504. In some embodiments, the immersion fluid in the line 122 can be split and diverges into a first stream that flows through the convective booster circuitTS0086-W001504 and a second stream that is routed to the compressor 106 (e.g., via the vapor intake line 112 or a bypass line connected to the line 116). In some embodiments, the cooling system 502 can be combined with flash gas bypass (FIG. 5). In such embodiments, the immersion fluid vapor 38 being drawn into the vapor intake line 112 and the immersion fluid bypassing the convective booster circuit converge in the line 116 upstream of the compressor 106. Alternatively, the immersion fluid being drawn into the vapor intake line 112 does not converge with the immersion fluid that bypasses the convective booster circuit 504 and, instead, the two streams can be introduced to the compressor 106 at separate stages. For example, the convective booster circuit 504 can be implemented in the system 502 in conjunction with a two- stage of “vapor-injection” compressor 106 in which immersion fluid vapor 38, which is at a relatively lower flow and lower pressure, enters a low-pressure stage of the compressor 106 while the intermediate stage receives immersion fluid that bypasses the convective booster circuit 504 and is at relatively higher pressure and flow.

[0089] Still referring to FIG. 6, the cooling system 502 also includes a liquid receiver bypass circuit 514, also referred to as a subcooling bypass circuit 514. The liquid receiver bypass circuit 514 is positioned for routing the condensed immersion fluid around the liquid receiver 124. The liquid receiver bypass circuit 514 includes a bypass valve 516 that is selectively actuated to allow the immersion fluid to enter the liquid receiver bypass circuit 514. Advantageously, the liquid receiver bypass circuit 514 routes the condensed immersion fluid around the liquid receiver 124 such that subcooled immersion fluid can be directed through the convective booster circuit 504. In the illustrated example, the liquid receiver bypass circuit 514 routes the condensed immersion fluid around the liquid receiver 124 and back towards the liquid line 122 upstream from the expansion device 110. In other embodiments, the liquid receiver bypass circuit 514 routes the condensed immersion fluid around the liquid receiver 124 and back towards the liquid line 122 downstream from the expansion device 110. In some embodiments, the liquid receiver bypass circuit 514 routes the condensed immersion fluid around the liquid receiver 124 and directly towards the convective booster circuit 504.

[0090] While the invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changesTS0086-W001 may be made, and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention is not limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In addition, all numerical values identified in the detailed description shall be interpreted as though the precise and approximate values are both expressly identified.

Claims

TS0086-W001CLAIMSWhat is claimed is:

1. An immersion cooling system, comprising: an immersion cooling tank defining a cavity sized and shaped for retaining a liquid volume of an immersion fluid and at least one electrical component to be immersed in the liquid volume of the immersion fluid, and for defining a vapor clearance above the liquid volume of the immersion fluid; and a direct immersion fluid cooling system operable in conjunction with the immersion cooling tank, wherein the cooling system includes: a vapor intake line positioned at least partially within the vapor clearance of the immersion cooling tank, wherein the vapor intake line is operable to draw vapor phase of the immersion fluid therein; a heat exchanger positioned downstream from the vapor intake line and operable to reject heat from the immersion fluid; a liquid line connected between the heat exchanger and the immersion tank for returning the immersion fluid from the heat exchanger to the immersion tank; and optionally, a compressor connected between the vapor intake line and the heat exchanger for drawing a suction on the vapor intake line and pressurizing the immersion fluid upstream from the heat exchanger.

2. The immersion cooling system of claim 1, wherein the cooling system comprises an expansion device positioned on the liquid line.

3. The immersion cooling system of claim 2, wherein the cooling system comprises a liquid receiver positioned between the heat exchanger and the expansion device.

4. The immersion cooling system of claim 2 or claim 3, wherein the cooling system comprises a first bypass circuit for bypassing the expansion device.

5. The immersion cooling system of claim 4, wherein the first bypass circuit includes an isolation valve for selectively allowing the immersion fluid to flow through the first bypass circuit around the expansion device.TS0086-W0016. The immersion cooling system of claim 4 or claim 5, wherein the first bypass circuit includes a pump operable to move the immersion fluid through the cooling system.

7. The immersion cooling system of claim 6, wherein the cooling system comprises the compressor and a second bypass circuit for bypassing the compressor.

8. The immersion cooling system of claim 7, wherein the second bypass circuit includes a bypass valve for selectively allowing the immersion fluid to flow through the first bypass circuit around the compressor.

9. The immersion cooling system of any one of the preceding claims, wherein the cooling system comprises a heat recovery circuit for routing a portion of the immersion fluid around the heat exchanger and through a heat recovery heat exchanger.

10. The immersion cooling system of claim 9, wherein the heat recovery heat exchanger is operable to utilize thermal energy from the immersion fluid for one of comfort heating and water heating.

11. The immersion cooling system of claim 9, wherein the heat recovery heat exchanger is operable to utilize thermal energy from the immersion fluid for a boiler.

12. The immersion cooling system of any one of claims 9 to 11, wherein the heat recovery circuit includes a three-way valve for diverting the portion of the immersion fluid towards the heat recovery heat exchanger.

13. The immersion cooling system of any one of the preceding claims, comprising at least two of said immersion cooling tank, wherein the cooling system comprises at least two said vapor intake line, each one of the vapor intake lines positioned at least partially within the vapor clearance of a response one of the immersion cooling tanks.

14. The immersion cooling system of claim 13, wherein the cooling system is connected to the immersion tanks in parallel.TS0086-W00115. The immersion cooling system of claim 13, wherein the cooling system is connected to the immersion tanks in series.

16. The immersion cooling system of any one of the preceding claims, wherein the heat exchanger is elevated relative to the vapor intake line to enable operating the cooling system in a thermosiphon mode.

17. The immersion cooling system of any one of the preceding claims, wherein the cooling system further comprises a flash tank positioned on the liquid line and operable to separate vapor-phase and liquid-phase of the immersion fluid therein.

18. The immersion cooling system of claim 17, wherein the cooling system includes a gas bypass line connected between the flash tank and the compressor for routing the vapor-phase of the immersion fluid from the flash tank towards the compressor.

19. The immersion cooling system of claim 18, wherein the cooling system includes a control valve on the gas bypass line.

20. The immersion cooling system of any one of claims 17 to 19, wherein the liquid phase of the immersion fluid is routed from the flash tank towards the immersion tank.

21. The immersion cooling system of any one of the preceding claims, further comprising a convective booster circuit operable to route the immersion fluid downstream from the heat exchanger into intimate thermal connection with the at least one electrical component via at least one heat sink thermally coupled to the at least one electrical component.

22. The immersion cooling system of claim 21, wherein the convective booster circuit comprises at least one expansion valve upstream from the at least one heat sink.

23. The immersion cooling system of claim 21 or claim 22, wherein the convective booster circuit further comprises at least one pump upstream of the at least one heat sink.TS0086-W00124. The immersion cooling system of any one of claims 21 to 23, wherein the cooling system further comprises a liquid receiver positioned on the liquid line upstream from the convective booster circuit and downstream from the heat exchanger, and a liquid receiver bypass circuit for selectively routing condensed immersion fluid around the liquid receiver towards the convective booster circuit.

25. The immersion cooling system of any one of the preceding claims, wherein the immersion fluid is a dielectric fluid.

26. The immersion cooling system of any one of the preceding claims, wherein the heat exchanger of the cooling system is located in an outdoor environment.

27. The immersion cooling system of claim 26, wherein the cooling system comprises a fan operable to force an outdoor air stream across the heat exchanger.

28. A method for operating an immersion cooling system, the method comprising: immersing at least one electrical component in a liquid volume of an immersion fluid retained in an immersion cooling tank, wherein a vapor clearance is defined above the liquid volume of the immersion fluid; transferring heat from the at least one electrical component to the immersion fluid such that a vapor phase of the immersion fluid emerges from a surface of the liquid volume into the vapor clearance; drawing the vapor phase of the immersion fluid into a vapor intake line of a direct immersion fluid cooling system, wherein the vapor intake line is positioned at least partially within the vapor clearance; channeling the vapor phase of the immersion fluid from the vapor intake line to a heat exchanger of the cooling system, wherein heat is rejected from the immersion fluid in the heat exchanger; and returning the immersion fluid from the heat exchanger to the immersion tank via a liquid line.

29. The method of claim 28, further comprising pressurizing the immersion fluid downstream from the vapor intake line and upstream from the heat exchanger using a compressor.TS0086-W00130. The method of claim 28 or claim 29, further comprising expanding the immersion fluid downstream from the heat exchanger using an expansion device of the cooling system positioned on the liquid line.

31. The method of claim 30, further comprising collecting the immersion fluid in a liquid receiver of the cooling system positioned between the heat exchanger and the expansion device.

32. The method of claim 30 or claim 31, further comprising selectively bypassing the expansion device using a first bypass circuit.

33. The method of claim 32, further comprising selectively bypassing the expansion device by selectively actuating an isolation valve on the first bypass circuit.

34. The method of claim 32 or claim 33, further comprising channeling the immersion fluid through the cooling system using a pump positioned on the first bypass circuit.

35. The method of claims 29 and 34, further comprising selectively bypassing the compressor using a second bypass circuit.

36. The method of claim 35, further comprising selectively bypassing the compressor by selectively actuating a bypass valve positioned on the second bypass circuit.

37. The method of any one of claims 28 to 36, further comprising channeling at least a portion of the immersion fluid around the heat exchanger and through a heat recovery heat exchanger of a heat recovery circuit.

38. The method of claim 37, further comprising utilizing thermal energy rejected from the immersion fluid within the heat recovery heat exchanger for one of comfort heating and water heating.

39. The method of claim 37, further comprising utilizing thermal energy rejected from the immersion fluid within the heat recovery heat exchanger for a boiler.

40. The method of any one of claims 37 to 39, further comprising diverting at least the portion of the immersion fluid towards the heat recovery heat exchanger using a three-way valve of the heat recovery circuit.TS0086-W00141. The method of any one of claims 28 to 40, further comprising: immersing another at least one electrical component in a liquid volume of an immersion fluid retained in at least one other immersion cooling tank, wherein a vapor clearance is defined above the liquid volume of the immersion fluid in the at least one other immersion tank; in each at least one other immersion tank, transferring heat from the at least one electrical component to the immersion fluid such that a vapor phase of the immersion fluid emerges from a surface of the liquid volume into the vapor clearance of the immersion tank; in each at least one other immersion tank, drawing the vapor phase of the immersion fluid into another vapor intake line of the direct immersion fluid cooling system, wherein the another vapor intake line is positioned at least partially within the vapor clearance of the immersion tank; channeling the vapor phase of the immersion fluid from the vapor intake lines to the heat exchanger of the cooling system; and returning the immersion fluid from the heat exchanger to the immersion tanks via the liquid line.

42. The method of claim 41 , wherein the cooling system is connected to the immersion tanks in parallel.

43. The method of claim 41 , wherein the cooling system is connected to the immersion tanks in series.

44. The method of any one of claims 28 to 43, further comprising operating the cooling system in a thermosiphon mode wherein the immersion fluid is channeled through the cooling system using a natural motive force induced by convection.

45. The method of any one of claims 28 to 43, further comprising separating vaporphase and liquid-phase of the immersion fluid in a flash tank positioned on the liquid line.

46. The method of claim 45, further comprising channeling the vapor-phase of the immersion fluid from the flash tank towards the compressor via a gas bypass line connected between the flash tank and the compressor.

47. The method of claim 46, further comprising controlling flow of the vapor-phase of the immersion fluid using a control valve on the gas bypass line.TS0086-W00148. The method of any one of claims 45 to 47, further comprising drawing the liquidphase of the immersion fluid from the flash tank and channeling the liquidphase of the immersion fluid towards the immersion tank.

49. The method of any one of claims 28 to 48, further comprising channeling the immersion fluid through a convective booster circuit downstream from the heat exchanger, into intimate thermal connection with the at least one electrical component via at least one heat sink thermally coupled to the at least one electrical component.

50. The method of claim 49, further comprising reducing a pressure of the immersion fluid in the convective booster circuit using at least one control valve upstream from the at least one heat sink.

51. The method of claim 49 or claim 50, further comprising channeling the immersion fluid through the convective booster circuit using at least one pump positioned upstream of the at least one heat sink.

52. The method of any one of claims 49 to 51 , further comprising collecting the immersion fluid in a liquid receiver of the cooling system positioned between the heat exchanger and the convective booster circuit.

53. The method of claim 52, further comprising selectively routing condensed immersion fluid from the heat exchanger around the liquid receiver towards the convective booster circuit via a liquid receiver bypass circuit.

54. The method of any one of claims 28 to 53, wherein the immersion fluid is a dielectric fluid.

55. The method of any one of claims 28 to 54, wherein the heat exchanger of the cooling system is located in an outdoor environment.

56. The method of claim 53, further comprising forcing an outdoor air stream across the heat exchanger using a fan.

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