Immersion cooling systems including vapor-compression cooling loop

Abstract

An immersion cooling system includes an immersion cooling tank defining a cavity sized and shaped for retaining a liquid volume of a first fluid and at least one electrical component to be immersed in the liquid volume of the first fluid, and for defining a vapor clearance above the liquid volume of the first fluid, and a vapor compression system operable in conjunction with the immersion cooling tank. The vapor compression system includes a compressor for pressurizing a second fluid, a first heat exchanger positioned upstream from the compressor and at least partially within the vapor clearance of the immersion cooling tank, and a second heat exchanger positioned downstream from the compressor. The first heat exchanger is operable to transfer thermal energy from a vapor-phase of the first fluid in the vapor clearance to the second fluid. The second heat exchanger is operable to reject heat from the second fluid.

Description

TS0085-W001IMMERSION COOLING SYSTEMS INCLUDING VAPOR-COMPRESSION 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 a first fluid and at least one electrical component to be immersed in the liquid volume of the firstTS0085-W001 fluid, and for defining a vapor clearance above the liquid volume of the first fluid, and a vapor compression system operable in conjunction with the immersion cooling tank. The vapor compression system includes a compressor for pressurizing a second fluid, a first heat exchanger positioned upstream from the compressor and at least partially within the vapor clearance of the immersion cooling tank, and a second heat exchanger positioned downstream from the compressor. The first heat exchanger is operable to transfer thermal energy from a vapor-phase of the first fluid in the vapor clearance to the second fluid. The second heat exchanger is operable to reject heat from the second fluid.

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

[0006] In some embodiments of the immersion cooling system of the foregoing aspect, the vapor compression system includes a heat recovery circuit for routing a portion of the second fluid downstream from the compressor around the second 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 second fluid for comfort heating or water heating. In some embodiments, the heat recovery heat exchanger is operable to utilize thermal energy from the second fluid for a boiler. In some embodiments, the heat recovery circuit includes a three-way valve for diverting the portion of the second fluid downstream from the compressor towards the heat recovery heat exchanger.TS0085-W001

[0007] In some embodiments of the immersion cooling system of the foregoing aspect, the system includes at least two of said immersion cooling tank, and the vapor compression system includes at least two said first heat exchanger, each one of the first heat exchangers positioned at least partially within the vapor clearance of a respective one of the immersion cooling tanks. In some embodiments, the first heat exchangers of the vapor compression system are connected in parallel. In some embodiments, the first heat exchangers of the vapor compression system are connected in series.

[0008] In some embodiments of the immersion cooling system of the foregoing aspect, the system includes a liquid recirculation circuit to enable the first heat exchanger to operate in a flooded mode. In some embodiments, the liquid recirculation circuit includes a liquid accumulator positioned between the second heat exchanger and the first heat exchanger, and the liquid accumulator collects a liquid-phase of the second fluid that is channeled from the liquid accumulator to the first heat exchanger. In some embodiments, the liquid accumulator collects a vaporphase of the second fluid that is channeled from the liquid accumulator to the compressor. In some embodiments, the liquid recirculation circuit includes a first line connected between the liquid accumulator and the first heat exchanger and a second line connected between the first heat exchanger and the liquid accumulator. In some embodiments, the system further includes a pump positioned on one of the first line and the second line for moving the liquid-phase of the second fluid through the liquid recirculation circuit. In some embodiments, the system further includes a compressor bypass circuit connected to the second line of the recirculation circuit, and the compressor bypass circuit selectively routes the second fluid in the second line around the compressor. In some embodiments, the system further includes a float valve positioned upstream of the liquid accumulator for regulating flow of the second fluid into the liquid accumulator.

[0009] In some embodiments of the immersion cooling system of the foregoing aspect, the second heat exchanger is elevated relative to the first heat exchanger to enable operating the vapor compression system in a thermosiphon mode.

[0010] In some embodiments of the immersion cooling system of the foregoing aspect, the vapor compression system further includes a flash tank positionedTS0085-W001 between the second heat exchanger and the first heat exchanger and operable to separate vapor-phase and liquid-phase of the second fluid therein. In some embodiments, the vapor compression system includes a gas bypass line connected between the flash tank and the compressor for routing the vapor-phase of the second fluid from the flash tank towards the compressor. In some embodiments, the vapor compression system includes a control valve on the gas bypass line. In some embodiments, the liquid-phase of the second fluid is drawn from the flash tank and routed towards the first heat exchanger.

[0011] In some embodiments of the immersion cooling system of the foregoing aspect, the system further includes a direct-to-chip circuit operable to route a first portion of the second fluid downstream from the second 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, and a second portion of the second fluid downstream from the second heat exchanger is routed towards the first heat exchanger. In some embodiments, the direct-to-chip circuit includes a first line connected between a split point, at which the first and second portions of the second fluid downstream from the second heat exchanger diverge, and the at least one heat sink coupled to the at least one electrical component. In some embodiments, at least one control valve is positioned on the first line of the direct-to- chip circuit. In some embodiments, at least one pump is positioned on the first line of the direct-to-chip circuit. In some embodiments, the direct-to-chip circuit includes a second line connected between the at least one heat sink and the compressor. In some embodiments, the first and second portions of the second fluid converge upstream from the compressor. In some embodiments, the first and second portions of the second fluid do not converge upstream from the compressor. In some embodiments, the first portion of the second fluid is routed, via the second line of the direct-to-chip circuit, towards a first stage of the compressor and the second portion of the second fluid, exiting the first heat exchanger, is routed towards a second stage of the compressor.

[0012] In some embodiments of the immersion cooling system of the foregoing aspect, the first fluid is a dielectric fluid.TS0085-W001

[0013] In some embodiments of the immersion cooling system of the foregoing aspect, the second fluid is a refrigerant. In some embodiments, the refrigerant is selected from the group consisting of R1234zeE, R1336mzzZ, R1233zdE, R1336mzzE, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ, and a combination of any two or more thereof.

[0001] In some embodiments of the immersion cooling system of the foregoing aspect, the second fluid does not substantially include water or a water / glycol mixture.

[0014] In another aspect, an immersion cooling system includes an immersion cooling tank defining a cavity sized and shaped for retaining a liquid volume of a first fluid and at least one electrical component to be immersed in the liquid volume of the first fluid, and for defining a vapor clearance above the liquid volume of the first fluid, and a fluid cooling system operable in conjunction with the immersion cooling tank. The fluid cooling system circulates a second fluid and includes a first heat exchanger positioned at least partially within the vapor clearance of the immersion cooling tank, a second heat exchanger positioned downstream from the first heat exchanger, and, optionally, a compressor for pressurizing the second fluid in a vapor compression mode of the fluid cooling system. The first heat exchanger is operable to transfer thermal energy from a vapor-phase of the first fluid in the vapor clearance to the second fluid, and the second heat exchanger is operable to reject heat from the second fluid. The second heat exchanger is elevated relative to the first heat exchanger to enable operating the fluid cooling system in a thermosiphon mode.

[0015] In some embodiments of the immersion cooling system of the foregoing aspect, the fluid cooling system includes the compressor and an expansion device positioned between the second heat exchanger and the first heat exchanger. In some embodiments, the fluid cooling system includes a liquid receiver positioned between the second heat exchanger and the expansion device. In some embodiments, the fluid 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 second 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 second fluid towards the first heat exchanger. In some embodiments, the fluid cooling system includes a secondTS0085-W001 bypass circuit for bypassing the compressor. In some embodiments, the second bypass circuit includes a bypass valve for selectively allowing the second fluid to flow through the second bypass circuit around the compressor. In some embodiments, the fluid cooling system includes a heat recovery circuit for routing a portion of the second fluid downstream from the first heat exchanger around the second 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 second fluid for comfort heating or water heating. In some embodiments, the heat recovery heat exchanger is operable to utilize thermal energy from the second fluid for a boiler. In some embodiments, the heat recovery circuit includes a three-way valve for diverting the portion of the second fluid downstream from the first heat exchanger towards the heat recovery heat exchanger.

[0016] In some embodiments of the immersion cooling system of the foregoing aspect, the system includes at least two of said immersion cooling tank, and the fluid cooling system includes at least two said first heat exchanger, each one of the first heat exchangers positioned at least partially within the vapor clearance of a respective one of the immersion cooling tanks. In some embodiments, the first heat exchangers of the fluid cooling system are connected in parallel. In some embodiments, the first heat exchangers of the fluid cooling system are connected in series.

[0017] In some embodiments of the immersion cooling system of the foregoing aspect, the system further includes a liquid recirculation circuit to enable the first heat exchanger to operate in a flooded mode. In some embodiments, the liquid recirculation circuit includes a liquid accumulator positioned between the second heat exchanger and the first heat exchanger, and the liquid accumulator collects a liquid-phase of the second fluid that is channeled from the liquid accumulator to the first heat exchanger. In some embodiments, the liquid accumulator collects a vaporphase of the second fluid that is channeled from the liquid accumulator towards the second heat exchanger. In some embodiments, the liquid recirculation circuit includes a first line connected between the liquid accumulator and the first heat exchanger and a second line connected between the first heat exchanger and the liquid accumulator. In some embodiments, the system further includes a pump positioned on one of the first line and the second line for moving the liquid-phase ofTS0085-W001 the second fluid through the liquid recirculation circuit. In some embodiments, the fluid cooling system includes the compressor and a compressor bypass circuit connected to the second line of the recirculation circuit, and the compressor bypass circuit selectively routes the second fluid in the second line around the compressor. In some embodiments, the system further includes a float valve positioned upstream of the liquid accumulator for regulating flow of the second fluid into the liquid accumulator.

[0018] In some embodiments of the immersion cooling system of the foregoing aspect, the fluid cooling system includes the compressor and a flash tank positioned between the second heat exchanger and the first heat exchanger and operable to separate vapor-phase and liquid-phase of the second fluid therein. In some embodiments, the fluid cooling system includes a gas bypass line connected between the flash tank and the compressor for routing the vapor-phase of the second fluid from the flash tank towards the compressor. In some embodiments, the fluid cooling system includes a control valve on the gas bypass line. In some embodiments, the liquid-phase of the second fluid is drawn from the flash tank and routed towards the first heat exchanger.

[0019] In some embodiments of the immersion cooling system of the foregoing aspect, the system includes a direct-to-chip circuit operable to route a first portion of the second fluid downstream from the second 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, and a second portion of the second fluid downstream from the second heat exchanger is routed towards the first heat exchanger. In some embodiments, the direct-to-chip circuit includes a first line connected between a split point, at which the first and second portions of the second fluid downstream from the second heat exchanger diverge, and the at least one heat sink coupled to the at least one electrical component. In some embodiments, at least one control valve is positioned on the first line of the direct-to- chip circuit. In some embodiments, at least one pump is positioned on the first line of the direct-to-chip circuit. In some embodiments, the fluid cooling system includes the compressor and the direct-to-chip circuit includes a second line connected between the at least one heat sink and the compressor. In some embodiments, the first and second portions of the second fluid converge upstream from theTS0085-W001 compressor. In some embodiments, the first and second portions of the second fluid do not converge upstream from the compressor. In some embodiments, the first portion of the second fluid is routed, via the second line of the direct-to-chip circuit, towards a first stage of the compressor and the second portion of the second fluid, exiting the first heat exchanger, is routed towards a second stage of the compressor.

[0020] In some embodiments of the immersion cooling system of the foregoing aspect, the first fluid is a dielectric fluid.

[0021] In some embodiments of the immersion cooling system of the foregoing aspect, the second fluid is a refrigerant. In some embodiments, the refrigerant is selected from the group consisting of R1234zeE, R1336mzzZ, R1233zdE, R1336mzzE, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ, and a combination of any two or more thereof.

[0022] In some embodiments of the immersion cooling system of the foregoing aspect, the second fluid does not substantially include water or a water / glycol mixture.

[0023] Another aspect is a method of operating an immersion cooling system. The method includes: immersing at least one electrical component in a liquid volume of a first fluid retained in an immersion cooling tank, a vapor clearance being defined above the liquid volume of the first fluid; transferring heat from the at least one electrical component to the first fluid such that a vapor phase of the first fluid emerges from a surface of the liquid volume into the vapor clearance; condensing the vapor phase of the first fluid in a first heat exchanger of the fluid cooling system, the first heat exchanger being positioned at least partially within the vapor clearance, by transferring thermal energy from the vapor-phase of the first fluid to a second fluid circulating in the fluid cooling system; and channeling the second fluid from the first heat exchanger to a second heat exchanger of the fluid cooling system, heat being rejected from the second fluid in the second heat exchanger, and channeling the second fluid between the first heat exchanger and the second heat exchanger is performed using one of: in a vapor compression mode of the fluid cooling system, a compressor that pressurizes the second fluid between the first heat exchanger and the second heat exchanger; or in a thermosiphon mode of the fluid cooling system, a natural motive force induced by convection.TS0085-W001

[0024] In some embodiments of the method of the foregoing aspect, the method includes expanding the second fluid downstream from the second heat exchanger using an expansion device of the fluid cooling system. In some embodiments, the method includes collecting the second fluid in a liquid receiver of the fluid cooling system positioned between the second heat exchanger and the expansion device. In some embodiments, the method includes selectively bypassing the expansion device in a first bypass circuit of the fluid cooling system. In some embodiments, the method includes selectively bypassing the expansion device in the first bypass circuit by selectively actuating an isolation valve on the first bypass circuit. In some embodiments, the method includes channeling the second fluid through the first bypass circuit using a pump on the first bypass circuit. In some embodiments, the method includes selectively bypassing the compressor in a second bypass circuit of the fluid cooling system. In some embodiments, the method includes selectively bypassing the compressor in the second bypass circuit by selectively actuating a bypass valve on the second bypass circuit. In some embodiments, the method includes operating the fluid cooling system in a compressor-free mode. In some embodiments, the method includes channeling at least a portion of the second fluid through a heat recovery circuit of the fluid cooling system, around the second heat exchanger and through a heat recovery heat exchanger. In some embodiments, the method includes utilizing thermal energy rejected from the second 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 second fluid within the heat recovery heat exchanger for a boiler. In some embodiments, the method includes channeling at least the portion of the second fluid through the heat recovery circuit by selectively actuating a three-way valve to divert at least the portion of the second fluid around the second heat exchanger and towards the heat recovery heat exchanger.

[0025] 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 the first fluid retained in at least one other immersion cooling tank, a vapor clearance being defined above the liquid volume of the first fluid in the at least one other immersion tank; in each at least one other immersion tank, transferring heat from the another at least one electrical component to the first fluid such that a vapor phase ofTS0085-W001 the first 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, condensing the vapor phase of the first fluid in another first heat exchanger of the fluid cooling system, the another first heat exchanger being positioned at least partially within the vapor clearance of the immersion tank, by transferring thermal energy from the vaporphase of the first fluid to the second fluid circulating in the fluid cooling system; and channeling the second fluid from each first heat exchanger of the fluid cooling system to the second heat exchanger of the fluid cooling system. In some embodiments, the first heat exchangers of the fluid cooling system are connected in parallel. In some embodiments, the first heat exchangers of the fluid cooling system are connected in series.

[0026] In some embodiments of the method of the foregoing aspect, the method includes operating the first heat exchanger in a flooded mode using a liquid recirculation circuit. In some embodiments, the method includes collecting a liquidphase of the second fluid in a liquid accumulator positioned between the second heat exchanger and the first heat exchanger and channeling the liquid-phase of the second fluid from the liquid accumulator to the first heat exchanger. In some embodiments, the method includes collecting a vapor-phase of the second fluid in the liquid accumulator and channeling the vapor-phase of the second fluid from the liquid accumulator around the first heat exchanger. In some embodiments, the liquid-phase of the second fluid is channeled between the liquid accumulator and the first heat exchanger in a first line and between the first heat exchanger and the liquid accumulator in a second line. In some embodiments, the method includes channeling the liquid-phase of the second fluid through the first and second lines using a pump positioned on one of the first line and the second line. In some embodiments, the method includes bypassing the second fluid being channeled in the second line around the compressor in a compressor bypass circuit connected to the second line. In some embodiments, the method includes regulating flow of the second fluid into the liquid accumulator using a float valve positioned upstream of the liquid accumulator.

[0027] In some embodiments of the method of the foregoing aspect, the second heat exchanger is elevated relative to the first heat exchanger to enable operating the vapor compression system in the thermosiphon mode.TS0085-W001

[0028] In some embodiments of the method of the foregoing aspect, the method includes separating vapor-phase and liquid-phase of the second fluid in a flash tank positioned between the second heat exchanger and the first heat exchanger. In some embodiments, the method includes channeling the vapor-phase of the second 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 second fluid using a control valve on the gas bypass line. In some embodiments, the method includes drawing the liquid-phase of the second fluid from the flash tank and channeling the liquid-phase of the second fluid towards the first heat exchanger.

[0029] In some embodiments of the method of the foregoing aspect, the method includes channeling a first portion of the second fluid through a direct-to-chip circuit in which the first portion of the second fluid is routed downstream from the second 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, and channeling a second portion of the second fluid downstream from the second heat exchanger towards the first heat exchanger. In some embodiments, the first and second portions of the second fluid downstream from the second heat exchanger diverge at a split point, and the first portion of the second fluid is channeled from the split point towards the at least one heat sink coupled to the at least one electrical component via a first line of the direct-to-chip circuit. In some embodiments, the method includes controlling flow of the first portion of the second fluid using at least one control valve on the first line of the direct-to-chip circuit. In some embodiments, the method includes channeling the first portion of the second fluid in the first line of the direct-to-chip circuit using at least one pump on the first line of the direct-to-chip circuit. In some embodiments, the method includes channeling the first portion of the second fluid between the at least one heat sink and the compressor via a second line of the direct-to-chip circuit. In some embodiments, the method includes converging the first and second portions of the second fluid upstream from the compressor. In some embodiments, the first and second portions of the second fluid do not converge upstream from the compressor. In some embodiments, the method includes channeling the first portion of the second fluid, via the second line of the direct-to-chip circuit, towards a first stage of theTS0085-W001 compressor and channeling the second portion of the second fluid, exiting the first heat exchanger, towards a second stage of the compressor.

[0030] In some embodiments of the method of the foregoing aspect, the first fluid is a dielectric fluid.

[0031] In some embodiments of the method of the foregoing aspect, the second fluid is a refrigerant. In some embodiments, the refrigerant is selected from the group consisting of R1234zeE, R1336mzzZ, R1233zdE, R1336mzzE, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ, and a combination of any two or more thereof.

[0032] In some embodiments of the method of the foregoing aspect, the second fluid does not substantially include water or a water / glycol mixture.

[0033] 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

[0034] Various aspects and embodiments of the disclosure are described hereinbelow with references to the drawings, wherein:

[0035] FIG. 1 is a schematic view of an immersion cooling system that includes a conventional water / glycol cooling loop;

[0036] FIG. 2 is a schematic view of an electrical component of the immersion cooling system of FIG. 1 ;

[0037] FIG. 3 is a schematic view of first embodiment of an immersion cooling system that includes a vapor compression system in accordance with the present disclosure;

[0038] FIG. 4 is a schematic view of second embodiment of an immersion cooling system that includes a vapor compression system in accordance with the present disclosure;TS0085-W001

[0039] FIG. 5 is a schematic view of third embodiment of an immersion cooling system that includes a vapor compression system in accordance with the present disclosure;

[0040] FIG. 6 is a schematic view of fourth embodiment of an immersion cooling system that includes a vapor compression system in accordance with the present disclosure;

[0041] FIG. 7 is a schematic view of fifth embodiment of an immersion cooling system that includes a vapor compression system in accordance with the present disclosure;

[0042] FIG. 8 is a schematic view of sixth embodiment of an immersion cooling system that includes a vapor compression system in accordance with the present disclosure;

[0043] FIG. 9 is a schematic view of an electrical component of the immersion cooling system of FIGS. 7 and 8; and

[0044] FIG. 10 is a cross-sectional view of a cold plate of the electrical component of FIG. 9.

[0045] Wherever possible and appropriate, the same reference numbers will be used throughout the drawings to represent the same parts.DETAILED DESCRIPTION

[0046] 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.

[0047] 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 viableTS0085-W001 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.

[0048] Single phase immersion cooling has a long history in computer server cooling. There is no phase change in single phase immersion cooling. Instead, the 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.

[0049] 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.

[0050] 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.

[0051] 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 22TS0085-W001 may extend through both the lower surface 16 and the upper surface 18, depending upon the design needs of the immersion cooling system 10.

[0052] 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 working fluid or another suitable working fluid for use with an immersion cooling system. Examples of suitable working 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.

[0053] 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 than 1.9.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. 11 ,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.TS0085-W001

[0054] The fluid 26 (e.g., the dielectric working 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.

[0055] 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, or 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.

[0056] 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.

[0057] 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 electricalTS0085-W001 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 34 to act as a heat sink and absorb and / or release thermal energy generated by the chip 32.

[0058] 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.

[0059] 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. ProvisionalTS0085-W001Patent 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.

[0060] 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-condensable 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.

[0061] The vapor 38 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.

[0062] 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 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.

[0063] 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 coolingTS0085-W001 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 and exits as relatively warm cooling fluid. The warm cooling fluid is cooled by the fluid cooler 54.

[0064] 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.

[0065] 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.TS0085-W001

[0066] 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 the 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.

[0067] 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.

[0068] 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 operatingTS0085-W001 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 cooling 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.

[0069] 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.TS0085-W001TABLE 1. ASSUMPTIONS AND THE ESTIMATED PERFORMANCE OF THE IMMERSION COOLING SYSTEM 10 (FIG. 1) UNDER FOUR DIFFERENT OPERATING CONDITIONSTS0085-W001

[0070] pPUE - 1 can be calculated according to Eq. 1 below:

[0071] Turning now to FIGS. 3-8, embodiments of the present disclosure address the limitations and disadvantages associated with the use of fluid coolers 54 and chillers using a refrigerant-based vapor compression system in conjunction with the immersion tank 12. A vapor compression system is operably coupled to the immersion tank 12 such that the vapor 38 can be condensed using direct thermal energy exchange with refrigerant of the vapor compression system, eliminating the need for an additional cooling loop 50 and facilitating more cost-effective and energy-efficient operation. The use of a vapor compression system in direct thermal energy exchange relationship 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.

[0072] In the embodiments of FIGS. 3-8, 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. 3-8, with like reference numerals indicating like elements and components. The elements and components of the embodiments described with reference to FIGS. 3-8 can be combined in any suitable combination. Accordingly, any feature or element described with reference to one of the embodiments of FIGS. 3-8 that is not described with reference to another one of the embodiments of FIGS. 3-8 is not to be interpreted as limiting in any sense, and such element and feature can be included in such other embodiment unless expressly stated otherwise or the context clearly indicates otherwise.

[0073] FIG. 3 illustrates a first embodiment of an immersion cooling system 100 that includes the immersion tank 12 and a vapor compression system 102 operably coupled to the immersion tank 12. The vapor compression system 102 is also referred to as a fluid cooling system 102. The vapor compression system 102 operates to circulate a working fluid (e.g., refrigerant) through a vapor compression loop 104, in which the working fluid undergoes phase changes to enable the refrigerant to absorb and reject thermal energy along the loop 104. The working fluidTS0085-W001 includes any refrigerant or other working fluid that is suitable for use in a vapor compression system. Multiple refrigerant options are possible including, but not limited to, R1234zeE, R1336mzzZ, R1233zdE and R1336mzzE. Other refrigerant options include, but are not limited to, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ or mixture of thereof. Suitably, the working fluid in the vapor compression system 102 does not substantially include water or a water / glycol mixture, as opposed to the fluid cooling loop 50 of FIG. 1. Alternatively stated, water or water / glycol mixture is not a primary component of the working fluid. The working fluid may include trace amounts of water or water / glycol while still not “substantially” including these components.

[0074] Phase change of the working fluid in the vapor compression loop 104 is facilitated using various components of the vapor compression system 102 positioned on the loop 104. In the embodiment of FIG. 3, the vapor compression system 102 includes a compressor 106, a condenser 108, an expansion device 110 (e.g., an expansion valve), and an evaporator 112. The compressor 106 includes any suitably compressor that facilitates pressurizing the working fluid including, but not limited to, scroll, reciprocating, rotary, screw, and centrifugal compressors. The compressor 106 is positioned on the loop 104 between the evaporator 112 and the condenser 108. The expansion device 110 is positioned between the condenser 108 and the evaporator 112. Each of the evaporator 112 and the condenser 108 include any suitable heat exchanger design, such as coils, concentric tubes, shell and tube, microchannels, etc. The evaporator 112 and / or the condenser 108 can include one or multiple heat exchangers. The evaporator 112 is also referred to as a first heat exchanger 112 of the vapor compression system 102 and the condenser 108 is also referred to as a second heat exchanger 108 of the vapor compression system 102.

[0075] The evaporator 112 is at least partially positioned in the immersion tank 12, and is wholly or partially immersed in the vapor 38 of the immersion tank 12 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 evaporator 112. Any amount of the evaporator 112 may be in thermal communication with the vapor 38. Suitable positions of the evaporator 112 include those described above for the condenser 52 with reference to FIG. 1. The evaporator 112 is referred to as such with reference to the phase change (vaporization) that the working fluid in the vapor compression loopTS0085-W001104 undergoes within the evaporator 112. The evaporator 112 also operates to condense the immersion fluid 26 on the external surface of the evaporator, similar to the condenser 52 described with reference to FIG. 1.

[0076] In the example embodiment of FIG. 3, the condenser 108 transfers heat between working 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 working fluid in the condenser 108 and transferred to the air. Alternatively, the condenser 108 can transfer thermal energy between the working fluid in the vapor compression loop 104 and any other fluid suitable for rejecting thermal energy into. For example, the condenser 108 can be water cooled.

[0077] In one example operation of the vapor compression system 102, the compressor 106 receives the working fluid as a low pressure gas from the evaporator 112 through a low pressure line 116. The compressor 106 compresses the low pressure working fluid at this stage, raising the temperature and pressure of the working fluid. The compressed, high temperature working 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 working fluid is condensed to a compressed, liquid. The compressed, condensed working fluid exiting the condenser 108 is channeled via a line 120 towards and passes through the expansion device 110 that expands the working fluid, reducing its pressure. The expanded working fluid exiting the expansion device 110 is a gas or a mixture of gas and liquid and is channeled via a line 122 towards and passes through the evaporator 112. The evaporator 112 transfers thermal energy from the vapor 38 emerging from the surface 36 of the liquid immersion fluid 26, into the uncompressed working fluid which absorbs the thermal energy and evaporates to a gas within the evaporator 112. The uncompressed, gas working fluid exiting the evaporator 112 is channeled back towards the compressor 106 via the line 116, where the working fluid is again compressed and the process repeats.

[0078] In the example embodiment of FIG. 3, the vapor compression system 102 includes additional components that provide greater versatility and flexibility withTS0085-W001 respect to operating modes of the vapor compression system 102 for condensing the vapor 38 in the immersion tank 12. For example, the vapor compression system 102 includes a liquid receiver 124, positioned on the line 120 for collecting condensed working fluid exiting the condenser 108 and, a first bypass circuit 126 positioned downstream from the liquid receiver 124, a second bypass circuit 128 positioned downstream from the evaporator 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 working fluid within the liquid receiver 124. Any one or more of these additional components can be included independent of the other additional components.

[0079] The first bypass circuit 126 is positioned for routing, in part or in whole, the working fluid from the line 120 around the expansion device 110, and back towards the evaporator 112 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.

[0080] The second bypass circuit 128 is positioned for routing, in part or in whole, the working fluid from the line 116 around the compressor 106, and back towards 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 working fluid to flow through the second bypass circuit 128, around the compressor 106.

[0081] 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 working 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 working fluid for use in heating applications, energy generation, or any suitable application that can benefit from the thermal energy rejected from the working fluid. The heatTS0085-W001 recovery heat exchanger 140 can have any suitable heat exchanger configuration, such as those described above for the evaporator 112 and the condenser 108.

[0082] Example operating modes of the vapor compression system 102 will now be described. The operating modes of the vapor compression system 102 are not limited to the operating modes described herein, and the vapor compression system 102 can be operated in any suitable mode without departing from the scope of the present disclosure.

[0083] In an example cooling mode of the vapor compression system 102, which is similar to the example operation of the vapor compression system 102 described above, both the bypass valve 128 and the isolation valve 126 are closed, thus restricting or limiting flow of the working fluid through the bypass circuits 126, 128. The compressor 106 pressurizes the low pressure working fluid flowing from the evaporator 112 via the line 116, and the compressed working fluid is routed or channeled to the condenser 108 where the working fluid condenses. The condensed working fluid is then routed via the line 120 towards the liquid receiver 124, where the liquid working fluid is collected upstream from the expansion device 110.

[0084] In an example heating mode of the vapor compression system 102, the three-way valve 138 is actuated to divert the working 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 can also be controlled to adjust a pressure of the working fluid in the heating mode, which varies the condensing temperature of the working fluid and the amount of thermal energy transferred via the heat recovery heat exchanger 140. For example, the condensing temperature of the working 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 working fluid. For example, the thermal energy extracted from the working 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 working fluid via the heat recovery heat exchanger 140 is used for a boiler.TS0085-W001

[0085] In an example “compressor free” mode of the vapor compression system 102, the pump 132 on the first bypass circuit 126 is used to circulate the working fluid through the evaporator 112 and towards the condenser 108 without operating the compressor 106. In this mode, the isolation valve 134 is open to enable the working fluid to flow through the first bypass circuit 126 and the bypass valve 136 is also opened to allow the working fluid to bypass the compressor 106 via the second bypass circuit 128. The vapor compression 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 working fluid at lower pressure). This enables the vapor compression system 102 to be operated in a more energy efficient manner since less power is required to move the working fluid using the pump 132 than is required to pressurize the working fluid using the compressor 106.

[0086] Another example compressor free mode of the vapor compression system 102 includes a thermosiphon mode in which the working fluid is circulated through the vapor compression loop 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 evaporator 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 vapor compression system 102 can be operated in the thermosiphon mode when outside ambient conditions allow (e.g., when the ambient temperature is cold enough to allow condensing the working fluid at lower pressure).

[0087] Table 2 below shows the performance of an example immersion cooling system, such as the immersion cooling system 100, that implements a vapor compression system, such as the vapor compression 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 about 90% and, in fact, surprisingly decreases the “pPUE - 1” by about 40% compared to the immersion cooling system in “cooling mode with chiller” reported in Table 1 (at aTS0085-W001“pPUE - 1” of 0.108). “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.TABLE 2. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A VAPOR COMPRESSION SYSTEM IN A COOLING MODE

[0088] Table 3 below shows the performance of an example immersion cooling system, such as the immersion cooling system 100, that implements a vapor compression system, such as the vapor compression 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 systemTS0085-W001 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 as much as 36%, depending on the refrigerant choice, compared to the immersion cooling system in the same mode of operation reported in Table 1 (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 3 to 6 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.TS0085-W001TABLE 3. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A VAPOR COMPRESSION SYSTEM IN A HEATING MODE FOR COMFORT HEATING

[0089] As described above, an immersion cooling system, such as the immersion cooling system 100, can implement a vapor compression system, such as the vapor compression system 102, operating in a heating mode to provide thermal energy to a boiler. The performance 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.TS0085-W001TABLE 4. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A VAPOR COMPRESSION SYSTEM IN A HEATING MODE FOR A BOILER

[0090] Table 5 below shows the performance of an example immersion cooling system, such as the immersion cooling system 100, that implements a vapor compression system, such as the vapor compression 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 5-10°C or more lower than the evaporating temperature of the chiller (Tevap_ch), it is possible to have compressor free operation with a pump only. For example, for a Tevap_ch of about 42°C, compressor free operation would be possible at outside ambient temps below about 37-32°C. Due to reduction in pump power, and the latent heat of vaporization of the refrigerant working 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.TS0085-W001TABLE 5. PERFORMANCE OF IMMERSION COOLING SYSTEM IMPLEMENTING A VAPOR COMPRESSION SYSTEM IN A COMPRESSOR FREE COOLING MODE

[0091] 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 a leak of working fluid from the vapor compression system 102. In case of a leak of the working fluid from the vapor compression system 102 into the immersion tank 12, a rise in pressure would likely occur and could be detected with the pressure sensor 142. The tank can then be immediately shut down to avoid overpressure and the potential formation of a flammable atmosphere inside the vapor space of the tank above the fluid surface 36, in case of flammable refrigerants used in the vapor compression loop 104.

[0092] 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 working fluid in the line 120 and the uncompressed, gas working fluid in the line 116, which can help increase energy efficiency and performance of the compressor 106.TS0085-W001

[0093] The vapor compression system 102 can provide a dedicated vapor compression loop 104 for condensing the immersion fluid 26 in a single immersion tank 12. Alternatively, the vapor compression system 102 can provide a cascading loop that condenses the immersion fluid 26 in multiple immersion tanks 12. In such embodiments, vapor compression 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 vapor compression system 102 of FIG. 3 connected in parallel to two immersion tanks 12. The immersion tanks 12 and the vapor compression system 102 have the same elements and components as described above with reference to FIGS. 1 and 3, respectively. The vapor compression 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.

[0094] In the example of FIG. 4, the working fluid in the line 122 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 202 where the working fluid is split into parallel streams at a split point 204. A first portion of the working fluid flows from the split point 204, in a first line 206 of the cascading circuit 202, and passes through a first evaporator 12a positioned at least partially in a first of the immersion tanks 12. A second portion of the working fluid flows from the split point 204, in a second line 208 of the cascading circuit 202, and passes through a second evaporator 12b positioned at least partially in a second of the immersion tanks 12. The first and second evaporators 12a, 12b can be configured and positioned as described above for the evaporator in FIG. 3. The evaporators 12a, 12b condense the immersion fluid 26 in the vapor 38 of the respective immersion tank 12, and the working fluid exiting the evaporators 12a, 12b flows in the respective lines 206, 208, which converge at a mixing valve 210. The working fluid from each line 206, 208 is mixed in the mixing valve 210 and is routed into the line 116 of the vapor compression system 102. In embodiments where the vapor compression system 102 is connected in series to multiple immersion tanks 12, the working fluid is not split but instead passes, in series, through the evaporators 12a, 12b associated with each immersion tank 12 in the series, and theTS0085-W001 working fluid is routed into the line 116 after passing through the final evaporator 12b in the series.

[0095] FIG. 5 illustrates a third embodiment of an immersion cooling system 300 that includes the immersion tank 12 and a vapor compression system 302 operably coupled to the immersion tank 12. The vapor compression system 302 includes similar elements and components as the vapor compression system 102, with like elements and components indicated by like reference numerals. Additionally, in this embodiment, the vapor compression system 302 includes a liquid recirculation circuit 302 downstream from the condenser 108. The liquid recirculation circuit 302 includes the evaporator 112 and allows the evaporator 112 to operate in a flooded mode, without superheat at the evaporator exit. This can further improve the overall energy efficiency of the vapor compression system 302 due to better heat transfer performance of the flooded evaporator 302 versus an evaporator that operates with a superheat. The expansion device 110 is omitted from this embodiment.

[0096] In the embodiment of FIG. 5, the condensed, compressed working fluid exiting the condenser 108 is routed via the line to the liquid recirculation circuit 302, where the working fluid enters into a liquid accumulator 310. The working fluid in the liquid accumulator 310 can be a two-phase (vapor-liquid) mixture, with liquid phase working fluid settling at the bottom of the accumulator 310. To ensure that a sufficient volume is contained in the liquid accumulator 310, a float valve is provided at the inlet of the accumulator 310 for regulating flow of the working fluid therein via the line 120.

[0097] The liquid phase working fluid in the liquid accumulator 310 is drawn into a first liquid recirculation line 306 using a pump 304 positioned on the liquid recirculation circuit 302 upstream from the evaporator 112. The pump 304 moves the liquid phase working fluid through first line 306 of the recirculation circuit 302, and the liquid phase working fluid passes through the evaporator 112 and is returned to the accumulator 310 via a second liquid recirculation line 308. The working fluid in the second recirculation line 308, having passed through the evaporator 112, may be a liquid-vapor mixture or substantially vapor phase. The vapor phase working fluid in the accumulator 310 settles above the liquid phase working fluid and is drawn into the suction line 116 via the compressor 106.TS0085-W001

[0098] The vapor compression system 302 of FIG. 5 also includes a compressor bypass circuit 314 which, similar to the bypass circuit 128 of the vapor compression system 102, routes working fluid around the compressor 106 when the system 302 is operating in a “compressor free” mode. As discussed above, the compressor free can be conveniently used when outside operating conditions allow. In this mode of the system 302, a three-way valve 316 is actuated to divert the working fluid from the liquid recirculation circuit 302 into the compressor bypass circuit 314. The liquid pump 304 routes the liquid phase working fluid to the evaporator 112 via the first recirculation line 306, from which the liquid-vapor mixture bypasses both the liquid accumulator 310 and the compressor 106, going directly to the condenser 108 (and / or the heat recovery circuit 130) before returning, as liquid-phase working fluid, to the liquid accumulator 310 via the line 120.

[0099] FIG. 6 illustrates a fourth embodiment of an immersion cooling system 400 that includes the immersion tank 12 and a vapor compression system 402 operably coupled to the immersion tank 12. The vapor compression system 402 includes similar elements and components as the vapor compression system 102, with like elements and components indicated by like reference numerals. Additionally, in this embodiment, the vapor compression 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 working fluid therein. The vapor-phase working fluid is drawn from the flash tank 406 into a bypass line 410 of the gas bypass circuit 404, while the liquid-phase working fluid is drawn from the flash tank 406 into the line 122 and is routed towards the evaporator 112. The working fluid within the evaporator 112 is then routed to the compressor 106 via the line 116 as described herein. The bypass line 410 of the gas bypass circuit 404 is connected to the inlet of the compressor 106, such that the vapor-phase working fluid in the bypass line 410 is also routed towards the compressor 106. A control valve 408 is positioned on the bypass line 410 for regulating flow of the vapor-phase working fluid being drawn from the flash tank 406 and / or entering the compressor 106 via the bypass line 410.

[0100] FIGS. 7 and 8 illustrate fifth and sixth embodiments, respectively, of an immersion cooling system 500 that includes the immersion tank 12 and a vapor compression system 502 operably coupled to the immersion tank 12. The vaporTS0085-W001 compression system 502 of FIGS. 7 and 8 includes similar elements and components as the vapor compression system 102, with like elements and components indicated by like reference numerals. Additionally, in these embodiments, the vapor compression system 502 includes a cold plate or “direct-to- chip” 504 that enables forced convective boiling of the working fluid in the vapor compression system 502.

[0101] With additional reference to FIGS. 9 and 10, to enable convective boiling of the working fluid of the vapor compression system 502, 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 working fluid. In the illustrated embodiment, one or more channels 44 is defined longitudinally through the cold plate 34 for receipt of the working fluid via a line 506 of the direct-to- chip 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 and routed toward the compressor 106 via line 508 of the circuit 504. The cold plate 34 acts as a heat sink between the chip 32 and the working fluid, with the working fluid flowing through the channels 44 of the cold plate 34 to effectuate convective boiling of the working fluid and cooling of the chip 32. Although described as having channels 44, 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 working fluid of the vapor compression system 502 is brought into heat transfer contact with the cold plate 34 using jet impingement or thin-film evaporation.

[0102] In some embodiments, the working fluid of the vapor compression system 502 moves through the direct-to-chip circuit 504 via a natural motive force induced by convection. As the working fluid boils within the channels 44 of the cold plate 34, the boiling working fluid, and resultant vapor, becomes less dense than the working fluid entering the cold plate 34 via the line 506, which causes the boiling working fluid to rise or otherwise flow towards the compressor 106. Additionally and / or alternatively, for the working fluid entering one or more of the cold plates 34, a pump 512 (FIG. 9) can be provided to force the working fluid through the channels 44 of the cold plate 34, inducing convective boiling of the working fluid therein. The pumpTS0085-W001512 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 the compressor 106 creates a pressure differential across the direct-to-chip circuit 504, which moves the working fluid through the lines 506, 508 and the cold plate 34 and towards the compressor 106.

[0103] One or more control valves 510 are also positioned on the line 506 of the circuit 504. In the illustrated example, a control valve 510 is provided for each cold plate 34 (i.e. , is positioned on each branch of the line 506 supplying working fluid to the respective cold plate 34) to regulate flow of the working fluid through the respective cold plate 34. The valves 510 can be manually actuatable, electronically actuatable, and combinations thereof. In some embodiments, each valve 510 may be utilized to bypass a respective pump 512 and enable the cold plate 34 to operate in a passive, or thermosiphon mode. A control valve 514 is also positioned on the line 508 of the direct-to-chip circuit 504, downstream from the cold plates 34, and can be used to control a flow and / or pressure of all the working fluid exiting the cold plates 34, having converged in the line 508, upstream from the compressor 106.The control valve 514 may be an expansion valve or other pressure control valve type.

[0104] In the embodiments of FIGS. 7 and 8, the working fluid in the line 122 (downstream from the condenser 108 and, optionally, the liquid receiver 124) is split at a split point 516 and diverges into a first stream that flows through the direct-to- chip circuit 504 and a second stream that flows through the expansion device 110 and the evaporator 112. The first stream, flowing through the direct-to-chip circuit 504, bypasses the evaporator 112. In this case, most of the heat from the electrical components 28, and more particularly the chips 32, is absorbed via the first stream of working fluid in the circuit 504, and as a result the evaporator 112 acts as a secondary or auxiliary heat exchange component and can use less working fluid. In some embodiments, the vapor compression system 502 can be combined with liquid recirculation (FIG. 5) or flash gas bypass (FIG. 6).

[0105] In some embodiments, as is shown in FIG. 7, the working fluid from the direct-to-chip circuit 504 and the working fluid exiting the evaporator 112 converge in the line upstream of the compressor 106. Alternatively, as illustrated in FIG. 8, theTS0085-W001 working fluid from the direct-to-chip circuit 504 does not converge with the working fluid from the evaporator 112 and, instead, the two streams can be introduced to the compressor 106 at separate stages. For example, the direct-to-chip circuit 504 can be implemented in the system 502 in conjunction with a two-stage of “vaporinjection” compressor 106 in which working fluid from the circuit 504, which is at a relatively lower flow and lower pressure, enters a low-pressure stage of the compressor 106 while the intermediate stage receives working fluid from the evaporator 112 which is at relatively higher pressure and flow.

[0106] 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 changes 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

TS0085-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 a first fluid and at least one electrical component to be immersed in the liquid volume of the first fluid, and for defining a vapor clearance above the liquid volume of the first fluid; and a vapor compression system operable in conjunction with the immersion cooling tank, wherein the vapor compression system includes: a compressor for pressurizing a second fluid; a first heat exchanger positioned upstream from the compressor and at least partially within the vapor clearance of the immersion cooling tank, wherein the first heat exchanger is operable to transfer thermal energy from a vapor-phase of the first fluid in the vapor clearance to the second fluid; and a second heat exchanger positioned downstream from the compressor and operable to reject heat from the second fluid.

2. The immersion cooling system of claim 1, wherein the vapor compression system comprises an expansion device positioned between the second heat exchanger and the first heat exchanger.

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

4. The immersion cooling system of claim 2 or claim 3, wherein the vapor compression 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 second fluid to flow through the first bypass circuit around the expansion device.TS0085-W0016. The immersion cooling system of claim 4 or claim 5, wherein the first bypass circuit includes a pump operable to move the second fluid towards the first heat exchanger.

7. The immersion cooling system of claim 6, wherein the vapor compression system comprises 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 second fluid to flow through the second bypass circuit around the compressor.

9. The immersion cooling system of any one of the preceding claims, wherein the vapor compression system comprises a heat recovery circuit for routing a portion of the second fluid downstream from the compressor around the second 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 second 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 second 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 second fluid downstream from the compressor 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 vapor compression system comprises at least two said first heat exchanger, each one of the first heat exchangers positioned at least partially within the vapor clearance of a respective one of the immersion cooling tanks.

14. The immersion cooling system of claim 13, wherein the first heat exchangers of the vapor compression system are connected in parallel.TS0085-W00115. The immersion cooling system of claim 13, wherein the first heat exchangers of the vapor compression system are connected in series.

16. The immersion cooling system of any one of the preceding claims, further comprising a liquid recirculation circuit to enable the first heat exchanger to operate in a flooded mode.

17. The immersion cooling system of claim 16, wherein the liquid recirculation circuit includes a liquid accumulator positioned between the second heat exchanger and the first heat exchanger, wherein the liquid accumulator collects a liquid-phase of the second fluid that is channeled from the liquid accumulator to the first heat exchanger.

18. The immersion cooling system of claim 17, wherein the liquid accumulator collects a vapor-phase of the second fluid that is channeled from the liquid accumulator to the compressor.

19. The immersion cooling system of claim 18, wherein the liquid recirculation circuit includes a first line connected between the liquid accumulator and the first heat exchanger and a second line connected between the first heat exchanger and the liquid accumulator.

20. The immersion cooling system of claim 19, further comprising a pump positioned on one of the first line and the second line for moving the liquidphase of the second fluid through the liquid recirculation circuit.

21. The immersion cooling system of claim 20, further comprising a compressor bypass circuit connected to the second line of the recirculation circuit, wherein the compressor bypass circuit selectively routes the second fluid in the second line around the compressor.

22. The immersion cooling system of any one of claims 17 to 21 , further comprising a float valve positioned upstream of the liquid accumulator for regulating flow of the second fluid into the liquid accumulator.

23. The immersion cooling system of any one of the preceding claims, wherein the second heat exchanger is elevated relative to the first heat exchanger to enable operating the vapor compression system in a thermosiphon mode.TS0085-W00124. The immersion cooling system of any one of the preceding claims, wherein the vapor compression system further comprises a flash tank positioned between the second heat exchanger and the first heat exchanger and operable to separate vapor-phase and liquid-phase of the second fluid therein.

25. The immersion cooling system of claim 24, wherein the vapor compression system includes a gas bypass line connected between the flash tank and the compressor for routing the vapor-phase of the second fluid from the flash tank towards the compressor.

26. The immersion cooling system of claim 25, wherein the vapor compression system includes a control valve on the gas bypass line.

27. The immersion cooling system of any one of claims 24 to 26, wherein the liquidphase of the second fluid is drawn from the flash tank and routed towards the first heat exchanger.

28. The immersion cooling system of any one of the preceding claims, further comprising a direct-to-chip circuit operable to route a first portion of the second fluid downstream from the second 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, wherein a second portion of the second fluid downstream from the second heat exchanger is routed towards the first heat exchanger.

29. The immersion cooling system of claim 28, wherein the direct-to-chip circuit includes a first line connected between a split point, at which the first and second portions of the second fluid downstream from the second heat exchanger diverge, and the at least one heat sink coupled to the at least one electrical component.

30. The immersion cooling system of claim 29, further comprising at least one control valve on the first line of the direct-to-chip circuit.

31. The immersion cooling system of claim 29 or claim 30, further comprising at least one pump on the first line of the direct-to-chip circuit.TS0085-W00132. The immersion cooling system of any one of claims 29 to 31 , wherein the direct- to-chip circuit includes a second line connected between the at least one heat sink and the compressor.

33. The immersion cooling system of claim 32, wherein the first and second portions of the second fluid converge upstream from the compressor.

34. The immersion cooling system of claim 32, wherein the first and second portions of the second fluid do not converge upstream from the compressor.

35. The immersion cooling system of claim 34, wherein the first portion of the second fluid is routed, via the second line of the direct-to-chip circuit, towards a first stage of the compressor and the second portion of the second fluid, exiting the first heat exchanger, is routed towards a second stage of the compressor.

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

37. The immersion cooling system of any one of the preceding claims, wherein the second fluid is a refrigerant.

38. The immersion cooling system of claim 37, wherein the refrigerant is selected from the group consisting of R1234zeE, R1336mzzZ, R1233zdE, R1336mzzE, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ, and a combination of any two or more thereof.

39. The immersion cooling system of any one of the preceding claims, wherein the second fluid does not substantially include water or a water / glycol mixture.

40. An immersion cooling system, comprising: an immersion cooling tank defining a cavity sized and shaped for retaining a liquid volume of a first fluid and at least one electrical component to be immersed in the liquid volume of the first fluid, and for defining a vapor clearance above the liquid volume of the first fluid; and a fluid cooling system operable in conjunction with the immersion cooling tank, the fluid cooling system circulating a second fluid, wherein the fluid cooling system includes:TS0085-W001 a first heat exchanger positioned at least partially within the vapor clearance of the immersion cooling tank, wherein the first heat exchanger is operable to transfer thermal energy from a vapor-phase of the first fluid in the vapor clearance to the second fluid; a second heat exchanger positioned downstream from the first heat exchanger and operable to reject heat from the second fluid, wherein the second heat exchanger is elevated relative to the first heat exchanger to enable operating the fluid cooling system in a thermosiphon mode; and optionally, a compressor for pressurizing the second fluid in a vapor compression mode of the fluid cooling system.

41. The immersion cooling system of claim 40, wherein the fluid cooling system comprises the compressor and an expansion device positioned between the second heat exchanger and the first heat exchanger.

42. The immersion cooling system of claim 41, wherein the fluid cooling system comprises a liquid receiver positioned between the second heat exchanger and the expansion device.

43. The immersion cooling system of claim 41 or claim 42, wherein the fluid cooling system comprises a first bypass circuit for bypassing the expansion device.

44. The immersion cooling system of claim 43, wherein the first bypass circuit includes an isolation valve for selectively allowing the second fluid to flow through the first bypass circuit around the expansion device.

45. The immersion cooling system of claim 43 or claim 44, wherein the first bypass circuit includes a pump operable to move the second fluid towards the first heat exchanger.

46. The immersion cooling system of claim 45, wherein the fluid cooling system comprises a second bypass circuit for bypassing the compressor.

47. The immersion cooling system of claim 46, wherein the second bypass circuit includes a bypass valve for selectively allowing the second fluid to flow through the second bypass circuit around the compressor.TS0085-W00148. The immersion cooling system of any one of claims 40 to 47, wherein the fluid cooling system comprises a heat recovery circuit for routing a portion of the second fluid downstream from the first heat exchanger around the second heat exchanger and through a heat recovery heat exchanger.

49. The immersion cooling system of claim 48, wherein the heat recovery heat exchanger is operable to utilize thermal energy from the second fluid for one of comfort heating and water heating.

50. The immersion cooling system of claim 48, wherein the heat recovery heat exchanger is operable to utilize thermal energy from the second fluid for a boiler.

51. The immersion cooling system of any one of claims 48 to 50, wherein the heat recovery circuit includes a three-way valve for diverting the portion of the second fluid downstream from the first heat exchanger towards the heat recovery heat exchanger.

52. The immersion cooling system of any one of claims 40 to 51 , comprising at least two of said immersion cooling tank, wherein the fluid cooling system comprises at least two said first heat exchanger, each one of the first heat exchangers positioned at least partially within the vapor clearance of a respective one of the immersion cooling tanks.

53. The immersion cooling system of claim 52, wherein the first heat exchangers of the fluid cooling system are connected in parallel.

54. The immersion cooling system of claim 52, wherein the first heat exchangers of the fluid cooling system are connected in series.

55. The immersion cooling system of any one of the preceding claims, further comprising a liquid recirculation circuit to enable the first heat exchanger to operate in a flooded mode.

56. The immersion cooling system of claim 55, wherein the liquid recirculation circuit includes a liquid accumulator positioned between the second heat exchanger and the first heat exchanger, wherein the liquid accumulator collectsTS0085-W001 a liquid-phase of the second fluid that is channeled from the liquid accumulator to the first heat exchanger.

57. The immersion cooling system of claim 56, wherein the liquid accumulator collects a vapor-phase of the second fluid that is channeled from the liquid accumulator towards the second heat exchanger.

58. The immersion cooling system of claim 57, wherein the liquid recirculation circuit includes a first line connected between the liquid accumulator and the first heat exchanger and a second line connected between the first heat exchanger and the liquid accumulator.

59. The immersion cooling system of claim 58, further comprising a pump positioned on one of the first line and the second line for moving the liquidphase of the second fluid through the liquid recirculation circuit.

60. The immersion cooling system of claim 58, wherein the fluid cooling system comprises the compressor and a compressor bypass circuit connected to the second line of the recirculation circuit, wherein the compressor bypass circuit selectively routes the second fluid in the second line around the compressor.

61. The immersion cooling system of any one of claims 56 to 60, further comprising a float valve positioned upstream of the liquid accumulator for regulating flow of the second fluid into the liquid accumulator.

62. The immersion cooling system of any one of claims 40 to 61 , wherein the fluid cooling system comprises the compressor and a flash tank positioned between the second heat exchanger and the first heat exchanger and operable to separate vapor-phase and liquid-phase of the second fluid therein.

63. The immersion cooling system of claim 62, wherein the fluid cooling system includes a gas bypass line connected between the flash tank and the compressor for routing the vapor-phase of the second fluid from the flash tank towards the compressor.

64. The immersion cooling system of claim 63, wherein the fluid cooling system includes a control valve on the gas bypass line.TS0085-W00165. The immersion cooling system of any one of claims 62 to 64, wherein the liquidphase of the second fluid is drawn from the flash tank and routed towards the first heat exchanger.

66. The immersion cooling system of any one of claims 40 to 65, further comprising a direct-to-chip circuit operable to route a first portion of the second fluid downstream from the second 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, wherein a second portion of the second fluid downstream from the second heat exchanger is routed towards the first heat exchanger.

67. The immersion cooling system of claim 66, wherein the direct-to-chip circuit includes a first line connected between a split point, at which the first and second portions of the second fluid downstream from the second heat exchanger diverge, and the at least one heat sink coupled to the at least one electrical component.

68. The immersion cooling system of claim 67, further comprising at least one control valve on the first line of the direct-to-chip circuit.

69. The immersion cooling system of claim 67 or claim 68, further comprising at least one pump on the first line of the direct-to-chip circuit.

70. The immersion cooling system of any one of claims 67 to 69, wherein the fluid cooling system comprises the compressor and the direct-to-chip circuit includes a second line connected between the at least one heat sink and the compressor.

71. The immersion cooling system of claim 70, wherein the first and second portions of the second fluid converge upstream from the compressor.

72. The immersion cooling system of claim 70, wherein the first and second portions of the second fluid do not converge upstream from the compressor.

73. The immersion cooling system of claim 72, wherein the first portion of the second fluid is routed, via the second line of the direct-to-chip circuit, towards aTS0085-W001 first stage of the compressor and the second portion of the second fluid, exiting the first heat exchanger, is routed towards a second stage of the compressor.

74. The immersion cooling system of any one of claims 40 to 73, wherein the first fluid is a dielectric fluid.

75. The immersion cooling system of any one of claims 40 to 73, wherein the second fluid is a refrigerant.

76. The immersion cooling system of claim 75, wherein the refrigerant is selected from the group consisting of R1234zeE, R1336mzzZ, R1233zdE, R1336mzzE, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ, and a combination of any two or more thereof.

77. The immersion cooling system of any one of claims 40 to 76, wherein the second fluid does not substantially include water or a water / glycol mixture.

78. A method of operating an immersion cooling system, the method comprising: immersing at least one electrical component in a liquid volume of a first fluid retained in an immersion cooling tank, wherein a vapor clearance is defined above the liquid volume of the first fluid; transferring heat from the at least one electrical component to the first fluid such that a vapor phase of the first fluid emerges from a surface of the liquid volume into the vapor clearance; condensing the vapor phase of the first fluid in a first heat exchanger of the fluid cooling system, wherein the first heat exchanger is positioned at least partially within the vapor clearance, by transferring thermal energy from the vapor-phase of the first fluid to a second fluid circulating in the fluid cooling system; and channeling the second fluid from the first heat exchanger to a second heat exchanger of the fluid cooling system, wherein heat is rejected from the second fluid in the second heat exchanger, and wherein channeling the second fluid between the first heat exchanger and the second heat exchanger is performed using one of:TS0085-W001 in a vapor compression mode of the fluid cooling system, a compressor that pressurizes the second fluid between the first heat exchanger and the second heat exchanger; or in a thermosiphon mode of the fluid cooling system, a natural motive force induced by convection.

79. The method of claim 78, further comprising expanding the second fluid downstream from the second heat exchanger using an expansion device of the fluid cooling system.

80. The method of claim 79, further comprising collecting the second fluid in a liquid receiver of the fluid cooling system positioned between the second heat exchanger and the expansion device.

81. The method of claim 79 or claim 80, further comprising selectively bypassing the expansion device in a first bypass circuit of the fluid cooling system.

82. The method of claim 81 , further comprising selectively bypassing the expansion device in the first bypass circuit by selectively actuating an isolation valve on the first bypass circuit.

83. The method of claim 82, further comprising channeling the second fluid through the first bypass circuit using a pump on the first bypass circuit.

84. The method of claim 82 or 83, further comprising selectively bypassing the compressor in a second bypass circuit of the fluid cooling system.

85. The method of claim 84, further comprising selectively bypassing the compressor in the second bypass circuit by selectively actuating a bypass valve on the second bypass circuit.

86. The method of claim 84 or claim 85, further comprising operating the fluid cooling system in a compressor-free mode.

87. The method of any one of claims 78 to 86, further comprising channeling at least a portion of the second fluid through a heat recovery circuit of the fluid cooling system, around the second heat exchanger and through a heat recovery heat exchanger.TS0085-W00188. The method of claim 87, further comprising utilizing thermal energy rejected from the second fluid within the heat recovery heat exchanger for one of comfort heating and water heating.

89. The method of claim 87, further comprising utilizing thermal energy rejected from the second fluid within the heat recovery heat exchanger for a boiler.

90. The method of any one of claims 87 to 89, further comprising channeling at least the portion of the second fluid through the heat recovery circuit by selectively actuating a three-way valve to divert at least the portion of the second fluid around the second heat exchanger and towards the heat recovery heat exchanger.

91. The method of any one of claims 78 to 90, further comprising: immersing another at least one electrical component in a liquid volume of the first fluid retained in at least one other immersion cooling tank, wherein a vapor clearance is defined above the liquid volume of the first fluid in the at least one other immersion tank; in each at least one other immersion tank, transferring heat from the another at least one electrical component to the first fluid such that a vapor phase of the first 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, condensing the vapor phase of the first fluid in another first heat exchanger of the fluid cooling system, wherein the another first heat exchanger is positioned at least partially within the vapor clearance of the immersion tank, by transferring thermal energy from the vaporphase of the first fluid to the second fluid circulating in the fluid cooling system; and channeling the second fluid from each first heat exchanger of the fluid cooling system to the second heat exchanger of the fluid cooling system.

92. The method of claim 91 , wherein the first heat exchangers of the fluid cooling system are connected in parallel.

93. The method of claim 91 , wherein the first heat exchangers of the fluid cooling system are connected in series.TS0085-W00194. The method of any one of claims 78 to 93, further comprising operating the first heat exchanger in a flooded mode using a liquid recirculation circuit.

95. The method of claim 94, further comprising collecting a liquid-phase of the second fluid in a liquid accumulator positioned between the second heat exchanger and the first heat exchanger and channeling the liquid-phase of the second fluid from the liquid accumulator to the first heat exchanger.

96. The method of claim 95, further comprising collecting a vapor-phase of the second fluid in the liquid accumulator and channeling the vapor-phase of the second fluid from the liquid accumulator around the first heat exchanger.

97. The method of claim 96, wherein the liquid-phase of the second fluid is channeled between the liquid accumulator and the first heat exchanger in a first line and between the first heat exchanger and the liquid accumulator in a second line.

98. The method of claim 97, further comprising channeling the liquid-phase of the second fluid through the first and second lines using a pump positioned on one of the first line and the second line.

99. The method of claim 98, further comprising bypassing the second fluid being channeled in the second line around the compressor in a compressor bypass circuit connected to the second line.

100. The method of any one of claims 95 to 99, further comprising regulating flow of the second fluid into the liquid accumulator using a float valve positioned upstream of the liquid accumulator.

101. The method of any one of claims 78 to 100, wherein the second heat exchanger is elevated relative to the first heat exchanger to enable operating the vapor compression system in the thermosiphon mode.

102. The method of any one of claims 78 to 101, further comprising separating vapor-phase and liquid-phase of the second fluid in a flash tank positioned between the second heat exchanger and the first heat exchanger.TS0085-W001103. The method of claim 102, further comprising channeling the vapor-phase of the second fluid from the flash tank towards the compressor via a gas bypass line connected between the flash tank and the compressor.

104. The method of claim 103, further comprising controlling flow of the vapor-phase of the second fluid using a control valve on the gas bypass line.

105. The method of any one of claims 102 to 104, further comprising drawing the liquid-phase of the second fluid from the flash tank and channeling the liquidphase of the second fluid towards the first heat exchanger.

106. The method of any one of claims 78 to 105, further comprising channeling a first portion of the second fluid through a direct-to-chip circuit in which the first portion of the second fluid is routed downstream from the second 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, and channeling a second portion of the second fluid downstream from the second heat exchanger towards the first heat exchanger.

107. The method of claim 106, wherein the first and second portions of the second fluid downstream from the second heat exchanger diverge at a split point, and the first portion of the second fluid is channeled from the split point towards the at least one heat sink coupled to the at least one electrical component via a first line of the direct-to-chip circuit.

108. The method of claim 107, further comprising controlling flow of the first portion of the second fluid using at least one control valve on the first line of the direct- to-chip circuit.

109. The method of claim 106 or claim 107, further comprising channeling the first portion of the second fluid in the first line of the direct-to-chip circuit using at least one pump on the first line of the direct-to-chip circuit.

110. The method of any one of claims 107 to 109, further comprising channeling the first portion of the second fluid between the at least one heat sink and the compressor via a second line of the direct-to-chip circuit.TS0085-W001111. The method of claim 110, further comprising converging the first and second portions of the second fluid upstream from the compressor.

112. The method of claim 110, wherein the first and second portions of the second fluid do not converge upstream from the compressor.

113. The method of claim 112, further comprising channeling the first portion of the second fluid, via the second line of the direct-to-chip circuit, towards a first stage of the compressor and channeling the second portion of the second fluid, exiting the first heat exchanger, towards a second stage of the compressor.

114. The method of any one of claims 78 to 113, wherein the first fluid is a dielectric fluid.

115. The method of any one of claims 78 to 114, wherein the second fluid is a refrigerant.

116. The method of claim 115, wherein the refrigerant is selected from the group consisting of R1234zeE, R1336mzzZ, R1233zdE, R1336mzzE, R513A, R514A, R515A, R515B, R1234yf, R744 R290, R600a, R1234zeZ, and a combination of any two or more thereof.

117. The method of any one of claims 78 to 116, wherein the second fluid does not substantially include water or a water / glycol mixture.

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