Two-phase immersion cooling equipment with active vapor management

Abstract

A two-phase immersion cooling apparatus may include an immersion tank having a main condenser in thermal communication with an interior volume of the immersion tank and a vapor management system fluidly connected to the immersion tank. The vapor management system may enable the apparatus to effectively manage periods of high vapor generation by removing vapor and other gases from a headspace of the immersion tank, condensing the vapor into liquid, and returning the liquid to the immersion tank.

Description

Technical Field

[0001] The present invention relates to a two-phase immersion cooling apparatus and method for cooling electronic devices. Background Art

[0002] Data centers house information technology (IT) equipment for storing, processing, and distributing data and applications. IT equipment may include electronic devices such as servers, storage systems, power distribution units, routers, switches, and firewalls.

[0003] IT equipment consumes electricity during use and generates heat as a byproduct. Data centers that house thousands of servers require dedicated IT cooling systems to manage the heat generated. Heat must be captured and removed from the data center. If the heat is not removed, the ambient temperature within the data center will rise above an acceptable threshold and temperature-induced performance limitations of electronic devices (e.g., microprocessors) may occur.

[0004] Data centers are energy-hungry facilities. It is not uncommon for data centers to use more than 50 times the energy per square foot of a typical commercial office building. Collectively, data centers account for approximately 3% of global electricity use.

[0005] The electricity usage of a data center can be attributed to various systems, including IT equipment, air management systems, mechanical systems, electrical systems (e.g., power conditioning systems), and cooling systems for IT equipment. Examples of IT cooling systems include precision air conditioning systems, direct expansion systems, chilled water systems, free cooling systems, humidification systems, and direct liquid cooling systems. In some data centers, IT cooling and power conditioning systems account for more than half of all electricity usage.

[0006] Most data centers use precision air conditioning systems for IT cooling. Precision air conditioners use a vapor compression cycle, similar to residential air conditioners. While air conditioning technology is well suited for comfort cooling office spaces, it is less suitable for cooling the thousands of relatively small thermal devices distributed throughout a large data center. The heat capacity of air is relatively low, so large volumes of air need to be moved and conditioned to cool IT equipment. As a result, the thermodynamic efficiency of the air conditioners is low, resulting in high operating costs. To reduce operating costs, servers need to be cooled more efficiently. Summary of the invention

[0007] Therefore, there is a need to improve the efficiency, performance, reliability and sustainability of IT cooling systems.

[0008] In a first aspect, the present invention relates to an immersion tank assembly. In some embodiments, the immersion tank assembly includes one or more immersion tanks and a steam management system, each immersion tank forming an internal volume, and the steam management system is fluidically connected to the immersion tank assembly. In some applications, each immersion tank may include an upper portion, a lower portion, and a main condenser thermally connected to the internal volume of the immersion tank, and the steam management system may include: a condensation chamber, the condensation chamber forming an internal volume and including an inlet, an outlet, and an auxiliary condenser thermally connected to the internal volume of the condensation chamber; a steam supply channel, which fluidly connects the upper portion of the immersion tank to the inlet of the condensation chamber; a valve, which is disposed in the steam supply channel between the upper portion of the immersion tank and the inlet of the condensation chamber; and a liquid return channel, which fluidly connects the outlet of the condensation chamber to the immersion tank assembly.

[0009] In some embodiments, the two-phase immersion cooling device may also include one or more of the following: a variable volume chamber, which is fluidly connected to the steam supply channel and is arranged between the upper part of the immersion tank assembly and the inlet of the condensation chamber; a pressure relief valve, which is fluidly connected to the condensation chamber; a sensor for detecting the pressure within the immersion tank assembly, the sensor being located in the immersion tank assembly and / or in the steam supply channel; a discharge channel, which is fluidly connected to the condensation chamber; a pressure relief valve, which is fluidly connected in the discharge channel; and a sensor for detecting the pressure within the steam management system and being located in the steam management system; a water a separator fluidly connected to the liquid return channel between the outlet of the condensing chamber and the inlet to the immersion tank assembly; a liquid pump fluidly connected to the liquid return channel and disposed between the outlet of the condensing chamber and the inlet to the immersion tank assembly; a dry filter fluidly connected to the liquid return channel and disposed between the outlet of the condensing chamber and the inlet to the immersion tank assembly; an impurity filter fluidly connected to the liquid return channel and disposed between the outlet of the condensing chamber and the inlet to the immersion tank assembly; and a steam pump fluidly connected to the steam supply channel and disposed between the upper portion of the immersion tank and the inlet of the condensing chamber.

[0010] In a second aspect, the present invention relates to an immersion tank assembly. In some embodiments, the immersion tank assembly includes one or more immersion tanks and a steam management system, each immersion tank forming an internal volume, and the steam management system is fluidically connected to the immersion tank assembly. In some applications, each immersion tank may include an upper portion, a lower portion, and a main condenser thermally connected to the internal volume, and the steam management system may include: a condensation chamber, which forms an internal volume and includes an inlet, an outlet, and an auxiliary condenser thermally connected to the internal volume of the condensation chamber; a steam supply channel, which fluidically connects the upper portion of the immersion tank to the inlet of the condensation chamber; a valve, which is arranged in the steam supply channel between the upper portion of the immersion tank and the inlet of the condensation chamber; and a liquid return channel, which fluidically connects the outlet of the condensation chamber to the inlet of the immersion tank assembly; a sensor, which is configured to be able to detect the pressure in the immersion tank assembly and generate and transmit a signal based on the measured pressure; and an electronic control unit, which is configured to be able to receive the signal from the sensor and send a command signal to the valve.

[0011] In some implementations, the sensor can be disposed in a steam supply passage between the immersion tank assembly and / or the valve and the immersion tank assembly. In some variations, the volume of the condensation chamber can be at least 10% of the headspace volume of the immersion tank. In some applications, the condensation chamber can also include a refrigerator fluidically connected to the auxiliary condenser. In some embodiments, the apparatus can also include a heat exchanger fluidically connected to the main condenser.

[0012] In a third aspect, the present invention relates to a method for immersion cooling a heat generating device. In some embodiments, the method includes providing a two-phase immersion cooling device; detecting the pressure in the immersion tank; at least one of the following: when the measured pressure in the immersion tank assembly is greater than a predetermined threshold setting (e.g., between -0.9 psig and 0.9 psig), opening a valve so that dielectric vapor and other gases from the immersion tank assembly are allowed to enter a condensation chamber; or when the measured pressure in the immersion tank assembly is less than a predetermined threshold setting, closing the valve; condensing the dielectric vapor and other gases into a liquid state in the condensation chamber; and returning the condensed dielectric liquid to the immersion tank assembly through a liquid return channel.

[0013] In some implementations, an immersion tank assembly is provided that may include one or more immersion tanks and a steam management system, each immersion tank forming an internal volume, and the steam management system is fluidically connected to the immersion tank assembly. In some applications, each immersion tank may include an upper portion, a lower portion, and a main condenser in thermal communication with the internal volume of the immersion tank, and the steam management system may include: a condensation chamber that forms an internal volume and includes an inlet, an outlet, and an auxiliary condenser in thermal communication with the internal volume of the condensation chamber; a steam supply channel that fluidly connects the upper portion of the immersion tank to the inlet of the condensation chamber; a valve disposed in the steam supply channel between the upper portion of the immersion tank and the inlet of the condensation chamber; and a liquid return channel that fluidly connects the outlet of the condensation chamber to the immersion tank assembly.

[0014] In some variations, the method may further include circulating a coolant through a primary condenser, the coolant having a temperature greater than or equal to the ambient air temperature and / or circulating a first coolant through the primary condenser and a second coolant through an auxiliary condenser, wherein the temperature of the first coolant is greater than the temperature of the second coolant.

[0015] In some implementations, the method may further include providing a steam pump fluidly connected to the steam supply channel and disposed between the immersion tank assembly and the inlet of the condensation chamber; and operating the steam pump while the valve is open to purge gas from the head space of the immersion tank and reduce the pressure within the immersion tank to below atmospheric pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A perspective view of a modular data center according to some embodiments of the present invention is shown.

[0017] Figure 2 Some embodiments of the present invention are shown Figure 1 A partial cutaway view of a modular data center exposing multiple immersion cooling tank assemblies within the container.

[0018] Figure 3 A perspective view of an immersion cooling tank assembly according to some embodiments of the present invention is shown.

[0019] Figure 4 A perspective view of a plurality of immersion cooling tank assemblies located in a conventional data center is shown, in accordance with some embodiments of the present invention.

[0020] Figure 5 A schematic diagram showing a two-phase immersion cooling apparatus with a vapor management system according to some embodiments of the present invention is shown.

[0021] Figure 6 FIG. 1 shows a flow control valve with an open flow control valve according to some embodiments of the present invention. Figure 5 equipment.

[0022] Figure 7 A diagram showing a flow control valve with an open flow control valve and an expanded bellows according to some embodiments of the present invention Figure 5 equipment.

[0023] Figure 8 Graphs showing immersion tank pressure and electronics power consumption over time according to some embodiments of the present invention.

[0024] Fig. 9 FIG. 1 shows a pressure relief valve with an open pressure relief valve according to some embodiments of the present invention. Figure 5 equipment.

[0025] Fig.10 A gravity-based water separator and filtration assembly according to some embodiments of the present invention is shown.

[0026] Fig.11 An alternative embodiment of a water separator according to some embodiments of the present invention is shown.

[0027] Fig.12 A refrigerator and an auxiliary condenser according to some embodiments of the present invention are shown.

[0028] Fig.13 A steam pump is shown having a steam pump included in a steam management system according to some embodiments of the present invention. Figure 5 equipment.

[0029] Fig.14 Graphs showing immersion tank pressure and electronic device power consumption over time as the tank pressure is pumped below atmospheric pressure before the electronic device is powered on, according to some embodiments of the present invention.

[0030] FIG. 15 shows a prior art immersion cooling system with a primary condenser.

[0031] FIG. 16 shows a prior art immersion cooling system having a main condenser and a freeboard condenser.

[0032] Fig.17 An embodiment of a two-phase immersion cooling apparatus having two immersion tanks fluidly connected to a central steam management system is shown according to some embodiments of the present invention.

[0033] Fig.18 A steam pump having a fluid connection between each immersion tank and a central steam management system is shown according to some embodiments of the present invention. Fig.17 equipment.

[0034] Fig.19 A steam treatment apparatus according to some embodiments of the present invention is shown.

[0035] Fig. 20 A steam processing apparatus having two steam supply inlets according to some embodiments of the present invention is shown.

[0036] Fig.21 A steam handling apparatus having a steam pump according to some embodiments of the present invention is shown.

[0037] Fig. 22 A steam processing apparatus having two steam supply inlets and two steam pumps is shown according to some embodiments of the present invention.

[0038] Fig.23 A system having a liquid level sensor included in a steam management system and a liquid pump included in a water separator and filter assembly according to some embodiments of the present invention is shown. Figure 5 equipment. DETAILED DESCRIPTION

[0039] Direct liquid cooling systems offer a promising alternative to air conditioning systems for data center applications. One form of direct liquid cooling is immersion cooling. In an immersion cooling system, the electronics are immersed in a dielectric fluid. Waste heat from the electronics is transferred to the fluid and then removed from the data center. Because waste heat is not released into the ambient air in the data center, sophisticated air conditioning systems are generally not required.

[0040] Immersion cooling systems can use single-phase or two-phase technology. In a single-phase immersion cooling system, the electronic device is immersed in a fluid, such as mineral oil. Waste heat from the electronic device is transferred to the fluid and warms the fluid. The warmed fluid is pumped from the immersion cooling system to a heat dissipation system, such as an evaporative cooling tower, dry cooler, or chilled water circulation system, which captures the waste heat from the fluid and removes the heat outside the data center.

[0041] One disadvantage of single-phase immersion cooling technology is that mineral oil can act as a solvent and, over time, remove identifying information from motherboards, processors, and other components. For example, product labels (e.g., stickers containing serial numbers and bar codes) and other markings (e.g., silk-screen information and model numbers on capacitors and other devices) can dissolve and wash away as mineral oil continuously flows over the device surface. As labels and inks are washed off the server, the mineral oil becomes contaminated and may need to be replaced, resulting in cost and scheduled downtime. Another disadvantage of single-phase immersion cooling is that servers cannot be maintained immediately after being removed from the tank. Typically, servers must be removed from the tank and allowed to drip dry for several hours before servicing. During this drying period, the server may be exposed to contaminants in the circulating air, and the presence of mineral oil on the server may attract and trap contaminants (e.g., dust or particles) on sensitive circuits, which may increase the risk of short circuits and failures.

[0042] In a two-phase immersion cooling system, the electronic device is immersed in a fluid in a tank, such as a hydrofluoroether. The fluid evaporates easily and leaves no residue, so the two-phase system does not suffer the disadvantages of the above-mentioned single-phase mineral oil-based system. During use, the waste heat from the electronic device is absorbed by the fluid, resulting in local evaporation of the fluid. The vapor rises into the head space of the tank and is condensed by the condenser. The heat from the vapor is transferred to the coolant circulating through the condenser, thereby warming the coolant. The warmed coolant is then pumped from the condenser to a heat dissipation system, such as an evaporative cooling tower, a dry cooler, or a chilled water circulation system, which captures the waste heat from the fluid and excludes the heat from the data center.

[0043] Two-phase immersion cooling systems exploit the benefits of phase change heat transfer, which makes them more efficient and capable of cooling electronic devices with high heat fluxes, such as high performance computing (HPC) servers with multiple graphics processing units (GPUs), than single-phase immersion cooling systems. However, the benefits of phase change heat transfer also bring challenges. In practice, maintaining steam within the system in prior art two-phase systems has proven to be challenging. Over time, existing two-phase immersion cooling systems inevitably suffer from fluid loss to the environment. On a regular basis, it can be costly to replenish the lost fluid. Examples of prior art two-phase cooling systems and their fluid loss patterns and other shortcomings are described below.

[0044] FIG. 15 shows a prior art example of a basic two-phase immersion cooling device 1500. Device 1500 includes an immersion tank 201, which is partially filled with a dielectric fluid 620 in a liquid phase. The device includes a condenser 235 installed in the head space of the tank 201. An electronic device 800 is immersed in the dielectric fluid. The electronic device can be a server including one or more microprocessors 801. The tank 201 is enclosed by a cover 225. When powered on and working, the electronic device 800 generates heat. The heat is transferred to the dielectric fluid 620, which causes a portion of the fluid to boil and form a dielectric vapor 615. The vapor 615 rises through the dielectric liquid 620 bath and enters the head space of the tank 201. When the vapor 615 contacts the condenser 235, it condenses into a liquid and is passively recycled back to the liquid bath, thereby completing the cycle of evaporation, condensation, precipitation and collection. During operation, the boiling of the dielectric fluid 620 with relatively large density produces the steam 615 with relatively small density, which expands and enters the head space occupied by non-condensable gas. The dielectric fluid 620 occupies a larger volume as a steam ratio liquid, therefore produces more steam 615 and enters the head space, and the tank pressure increases. In order to prevent the tank pressure from reaching an unsafe level, a pressure relief valve 460 is provided in the tank 201, and when pressure exceeds a predetermined threshold value, the pressure relief valve 460 is opened. Under the actuation of the pressure relief valve 460, the dielectric steam 615 is released from the tank 201 and lost in the environment. Over time, periodic valve actuation and fluid loss can exhaust fluid 620 and need to be supplemented.

[0045] In a variation of the example shown in FIG. 15 , the two-phase immersion cooling device 1500 may be configured to always maintain a tank pressure close to the ambient pressure (e.g., 1 atm). It would be desirable to operate at or near atmospheric pressure to minimize fluid loss due to leakage or diffusion through system joints or materials. When the heat load from the electronic device 800 increases, the rate of dielectric vapor generation increases and the pressure in the tank 201 increases. To avoid pressure accumulation, the pressure relief valve 460 can be actuated whenever the tank pressure rises above atmospheric pressure. During high-intensity computing, this may cause steam 615 to flow frequently to the environment. During idle periods, the heat load from the device 800 will decrease, and the rate of steam generation will decrease or even stop. Any remaining steam 615 is condensed by the condenser 235, and then the air in the head space is further cooled by the condenser 235, causing the tank pressure to drop below the ambient pressure. In order to relieve the negative pressure in the tank 201, the pressure relief valve 460 can be opened and allow ambient air to enter the tank 201. Over time, this periodic gas exchange causes fluid loss.

[0046] In another variation of the example shown in FIG. 15 , the two-phase immersion cooling apparatus 1500 can be equipped with a large-capacity condenser 235 whose cooling capacity exceeds the maximum heat load of the electronic device 800. The condenser 235 can be operated at a temperature significantly lower than the vapor temperature of the dielectric fluid 620, thereby ensuring that the vapor 615 is quickly condensed, thereby avoiding overpressure due to vapor accumulation. Although this approach reduces fluid losses, the condenser 235 is large and energy-intensive, which is costly and impractical for large-scale data center applications.

[0047] In another variation of the example shown in Figure 15, the two-phase immersion cooling device 1500 can be hermetically sealed. The tank 201 can be a pressure vessel capable of withstanding high positive or negative pressures without risk of failure. Unfortunately, pressure vessels are expensive to construct and maintain. For product liability reasons, the impact of high pressure operation on unique server models needs to be evaluated and approved before use, resulting in ongoing validation and liability burdens. High operating pressures may promote diffusion losses of fluids and accelerate aging of gaskets and other system components. In a sealed system, routine server maintenance requires shutting down the cooling system and opening the cover to access the server, which is time consuming. For these reasons, the hermetically sealed tank 201 is not a practical option for most data centers, particularly those with high uptime requirements.

[0048] FIG. 16 shows a second prior art example of a two-phase immersion cooling device 1600. Device 1600 includes an immersion tank 201, which is partially filled with a dielectric fluid 620 in a liquid phase. An electronic device 800 is immersed in the dielectric fluid 620. The electronic device 800 may be a server including one or more microprocessors 801. The immersion tank 201 is enclosed by a cover 225. Device 1600 may include two condensers. For example, device 1600 may include a main condenser 235 and a freeboard condenser 250 installed in the immersion tank 201. The main condenser 235 may be located above the liquid line 605 in the head space of the tank 201. The freeboard condenser 250 may be located at a distance above the main condenser 235 in the head space 206. In an example, the main condenser 235 may operate at a temperature of about 5°C to 15°C. The freeboard condenser 250 may operate at a lower temperature of about -28°C to -2°C. The apparatus 1600 has a high freeboard ratio, where the freeboard ratio is defined as the distance measured from the top of the main condenser 235 to the bottom surface of the cover 225 divided by the interior width of the immersion tank 201 .

[0049] During steady-state operation of the apparatus 1600, vapor 615 is generated as a result of the heat from the electronic device 800 evaporating the fluid 620 in the tank 201. The vapor 615 is heavier than the air 705, so a first zone 1605 containing saturated vapor 615 may settle above the liquid line 605. A second zone 1610 containing a mixture of vapor 615 and air 705 may form above the saturated vapor 615. A third zone 1615 containing primarily air 705 may form above the mixture of vapor 615 and air 705. The saturated vapor zone 1605 may be located between the liquid line 605 and the main condenser 235. The steam and air mixed zone 1610 may be located between the main condenser 235 and the freeboard condenser 250. The third zone 1615 containing primarily air 705 may be located between the freeboard condenser 250 and the cover 225. The main condenser 235 may be appropriately sized to condense most of the vapor 615 generated during steady-state operation. The freeboard condenser 250 may condense steam 615, which rises above the main condenser 235 and enters the second zone 1610. During steady state operation, there may be a balance of steam generation and condensation.

[0050] During periods of high utilization of the microprocessor 801, the device 800 consumes more power, generates more heat, and thus produces a higher steam generation rate. As the amount of steam 615 in the head space 206 increases, the depth of the saturated steam zone 1605 also increases. The freeboard condenser 250, which is maintained at a much lower temperature than the main condenser 235, can effectively condense the steam 615 that reaches it.

[0051] Although effective, the apparatus 1600 of FIG. 16 has certain drawbacks. First, the apparatus 1600 is inefficient because the freeboard condenser 250 requires a chiller to run continuously to maintain an appropriately low temperature. Second, the apparatus 1600 is not compact or user-friendly. To be effective, the apparatus 1600 must have a high freeboard ratio, which requires a relatively tall tank 201. While a tall tank 201 may be acceptable in a traditional data center with high ceilings and access by a lift or ladder to insert and remove electronic equipment into and from the tank 201, it is not suitable for compact applications, such as edge or mobile data center applications, where the system 1600 is installed in a confined space (e.g., a container 1005 ( Figure 1 and Figure 2 ) or utility enclosure). Despite these practical limitations, the cooling system 1600 of FIG. 16 may also experience fluid loss in a similar manner as the cooling system 1500 shown in FIG. 15 and described above.

[0052] In view of the foregoing examples, it would be desirable to provide a two-phase immersion cooling apparatus that is compact, energy efficient, inexpensive, and has minimal fluid losses to the environment.

[0053] Two-phase immersion cooling with active vapor management

[0054] Figure 5 An embodiment of a two-phase immersion cooling apparatus 100 with active steam management according to some embodiments of the present invention is shown. The two-phase immersion cooling apparatus 100 can be used in a variety of applications, from modular data centers 1000 (such as Figure 1 ) to the traditional data center 2000 (as shown Figure 4 ). Figure 1 In the embodiment of the present invention, the immersion cooling device 100 can be positioned in the container 1005 ( Figure 1 and Figure 2 ) and is fluidically connected to an external cooling system 240 mounted on top of the container 1005.

[0055] The apparatus 100 may include an immersion tank assembly 200. The immersion tank assembly 200 may include an immersion tank 201, which may be covered by a cover 225 ( Figure 3 ) is selectively sealed. The immersion tank 201 can be vertically compact, allowing it to be arranged in a confined space, such as a container 1005 or utility enclosure associated with a modular or edge data center application. The height of the immersion tank 201 can be less than the length or width of the tank 201. The height of the immersion tank 201 can be less than the length and width of the tank 201.

[0056] The immersion tank 201 may have an upper portion 205 and a lower portion 210. The upper portion 205 may be a portion of the immersion tank 201 located above the liquid line 605. The lower portion 210 may be a portion of the immersion tank 201 located below the liquid line 605. The liquid line 605 may be an interface between a gas (e.g., air and dielectric vapor) formed in the head space and a dielectric liquid 620 in the lower portion 210 of the immersion tank 201. The immersion tank 201 may have an opening 220 in the upper portion 205. The tank 201 may have an electrically insulating layer 230 on an interior surface. The immersion tank may have a lid 225. When open, the lid 225 may provide access to the interior volume 215 of the immersion tank 201 to facilitate insertion and removal of an electronic device 800 (e.g., a server, switch, or power electronics). When closed, the lid 225 may enclose the opening 220 and prevent vapor loss. The cover 225 may seal the opening 220 (eg, hermetically).

[0057] The immersion tank 201 can be partially filled with a (e.g., dielectric) fluid 620. The fluid 620 can be selected, or formulated by mixing two or more fluids, to have a boiling point below the operating temperature of the heat-generating electronic device 800 (e.g., microprocessor 801). When the electronic device 800 is operating, the fluid 620 in contact with the device 800 may partially boil and produce vapor 615. The vapor 615 can rise through the fluid bath and into the head space 206 of the immersion tank 201. The vapor 615 can settle on top of the liquid line 605, forming a blanket of saturated vapor 625.

[0058] The immersion tank assembly 200 may include a main condenser 235. The main condenser 235 may be located in the head space 206 of the tank 201. The main condenser 235 may condense the steam 615 within the immersion tank 201. In some implementations, the main condenser 235 may be a cooling coil, and more particularly, a cooling coil that receives a coolant (such as chilled water, a water-glycol mixture, a refrigerant, and the like) from a heat dissipation system 240 (such as an evaporative cooling tower, a dry cooler, or a chilled water loop). The heat dissipation system 240 may include a coolant pump 245, such as Figure 1 and Figure 5 The coolant pump 245 can circulate the coolant through the main condenser 235 and the heat dissipation system 240.

[0059] To minimize energy consumption, the main condenser 235 can operate at room temperature or slightly above room temperature. In one embodiment, when the ambient temperature is 30°C, the main condenser 235 can receive the coolant at a temperature of about 33°C and circulate the coolant. In another embodiment, the main condenser 235 can receive the coolant at a temperature of about 25°C to 40°C and circulate the coolant. In yet another embodiment, the main condenser 235 can receive the coolant at a temperature of about 30°C to 36°C and circulate the coolant. In another embodiment, the main condenser 235 can receive the coolant at a temperature of about 0 to 10 degrees above the ambient air temperature and circulate the coolant. In another embodiment, the main condenser 235 can receive the coolant at a temperature of about 0 to 15 degrees above the ambient air temperature and circulate the coolant.

[0060] The apparatus 100 may include a vapor management system 400. The vapor management system 400 may be fluidly connected to the immersion tank 201. When necessary, the vapor management system 400 may receive vapor 615 from the immersion tank 201 to avoid over-pressurization of the tank 201, condense the vapor 615 into liquid 620, and return the liquid 620 to the immersion tank 201 for reuse. The vapor management system 400 may be at least partially located outside the head space 206 of the immersion tank 201.

[0061] The steam management system 400 can be an auxiliary steam management system, for example, an external steam management system. The steam management system 400 can be enabled during periods of high, variable, or continuous steam generation. The steam management system 400 can be enabled or disabled based on one or more system variables (e.g., tank pressure, tank temperature, or device power). The steam management system 400 can provide excess condensing capacity to manage periods of increased heat load and steam generation, thereby supplementing the condensing capacity of the main condenser 235 when needed.

[0062] The vapor management system 400 may be actively controlled based on conditions measured or determined in the apparatus 100. For an embodiment, the vapor management system 400 may be controlled based on input of one or more variables, such as pressure, temperature, device power, vapor concentration, or opacity within the immersion tank 201. The variables may be measured with electronic sensors, mechanically detected, based on evaluation of related variables, or determined by any other suitable techniques and combinations thereof.

[0063] The steam management system 400 may include a steam supply channel 405. The steam supply channel 405 may fluidly connect the steam management system 400 to the upper portion 205 of the immersion tank 201. The steam supply channel 405 may be any suitable type of fluid channel, such as, for example, a tube, a pipe, an integrally formed channel, or a combination thereof.

[0064] The vapor management system 400 may include a liquid return channel 470. The liquid return channel 470 may fluidly connect the vapor management system 400 to the lower portion 210 of the immersion tank 201. The liquid return channel 470 may be any suitable type of fluid channel, such as a tube, a pipe, or an integrally formed channel, and combinations thereof. The vapor supply channel 405 and the liquid return channel 470 together may enable fluid to circulate from and to the immersion tank 201. For example, the vapor management system 400 may receive dielectric vapor 615 from the immersion tank 201 and return liquid dielectric fluid 620 to the immersion tank 201.

[0065] The steam management system 400 may include a valve 410 in the steam supply passage 405. The (e.g., flow control) valve 410 may control the flow of steam through the steam supply passage 405. When open, the valve 410 may allow steam to flow through the steam supply passage 405 and from the immersion tank 201 to the steam management system 400. The valve 410 may be a manual or automatic valve. The valve 410 may have a threshold (e.g., fixed or variable) pressure setting. In one embodiment, the threshold pressure setting may be about 0.15 psig. In this embodiment, the valve 410 will open when the pressure in the immersion tank is greater than or equal to 0.15 psig. The valve 410 may remain open until the steam pressure in the immersion tank 201 drops below 0.15 psig, at which time the valve 410 may be closed. In another embodiment, the threshold pressure setting may be between -0.15 psig and 0.15 psig or between -0.15 psig and 0.15 psig. In another embodiment, the threshold pressure setting may be -0.25psig and 0.25psig or between -0.25psig and 0.25psig. In another embodiment, the threshold pressure setting may be -0.9psig and 0.9psig or between -0.9psig and 0.9psig. In another embodiment, the threshold pressure setting may be 0psig and 0.25psig or between 0psig and 0.25psig. In another embodiment, the threshold pressure setting may be -0.25psig and 0psig or between -0.25psig and 0psig. In another embodiment, the threshold pressure setting may be 1psig and 5psig or between 1psig and 5psig. In another embodiment, the threshold pressure setting may be 4psig and 10psig or between 4psig and 10psig. In another embodiment, the threshold pressure setting may be -1psig and -5psig or between -1psig and -5psig. In another embodiment, the threshold pressure setting may be at or between -4 psig and -10 psig.

[0066] In some embodiments, the threshold pressure setting may be variable rather than fixed. A variable pressure setting may be helpful in handling surges in steam production that are expected during transient operation. For example, when device power consumption increases rapidly, there may be a time lag before the rise in steam pressure is detected by pressure monitoring. The rise in steam production may be accurately predicted by monitoring device power consumption. Upon detection of an increase in device power consumption, the threshold setting may be temporarily lowered to enable the steam management system 400 more quickly than using a fixed threshold setting.

[0067] In some applications, the steam management system 400 may include a condensation chamber 430. The condensation chamber may be a fixed volume condensation chamber. The condensation chamber 430 may have an internal volume disposed between an inlet 435 and an outlet 440. The steam supply channel 405 may be fluidly connected to the inlet 435 of the condensation chamber 430. The steam supply channel 405 may fluidly connect the outlet of the valve 410 to the inlet 435 of the condensation chamber 430. When the valve 410 is open, the steam supply channel 405 may transport steam 615 from the immersion tank 201 to the condensation chamber 430. The volume of the condensation chamber 430 may be at least 10% of the headspace volume of the immersion tank 201. The volume of the condensation chamber 430 may be at least 30% of the headspace volume of the immersion tank 201. The volume of the condensation chamber 430 may be at least 50% of the headspace volume of the immersion tank 201. The volume of the condensation chamber 430 may be at least 70% of the headspace volume of the immersion tank 201. The headspace volume may be the volume measured between the liquid line 605 and the inner surface of the cover 225 , and bounded by the side walls of the immersion tank 201 .

[0068] The condensation chamber 430 may include an auxiliary condenser 451. The auxiliary condenser 451 may be in thermal communication with the condensation chamber 430. The auxiliary condenser 451 may extract heat from the steam 615 and condense the steam 615 in the condensation chamber 430. The auxiliary condenser 451 may extend into the interior volume of the condensation chamber 430 or contact at least one surface of the condensation chamber 430. The auxiliary condenser 451 may operate at a lower temperature than the main condenser 235. In one embodiment, the auxiliary condenser 451 may include a cooling coil connected to a liquid refrigerator 446. The liquid refrigerator 446 may circulate a refrigerated coolant through the auxiliary condenser 451. In one embodiment, the liquid refrigerator 446 may circulate a liquid at a temperature of about 5 to 15°C. In another embodiment, the liquid refrigerator 446 may circulate a liquid at a temperature of about -2 to 10°C. In another embodiment, the liquid refrigerator 446 may circulate a liquid at a temperature of about -10 to -5°C. In another embodiment, the liquid chiller 446 may circulate liquid at a temperature of approximately -28 to -2°C.

[0069] In one variation, the liquid cooler 446 may be a refrigeration system such as Fig.12 The refrigerator 446 may include a pump 452 that circulates a fluid between a reservoir 453 and a cooling coil 451 to maintain the cooling coil at a temperature (T c) below. The fluid can be a dielectric fluid. The fluid can be the same type of fluid used in the immersion tank 201 to reduce the risk of cross contamination due to leakage or diffusion. Using the same type of fluid can also simplify maintenance tasks. The liquid refrigerator 446 may include a compressor 449, a condenser 447, an expansion valve 450 and an evaporator 448. The liquid refrigerator 446 may use a refrigeration cycle to extract heat from the fluid in the storage 453 and dissipate heat through the condenser 447.

[0070] The steam management system 400 may include a variable volume chamber 415 (e.g., a bellows). The variable volume chamber 415 may be made of a steam resistant material, such as a metalized polyester film (e.g., Mylar), having an expandable internal volume. When the pressure in the steam management system 400 is less than or equal to 1 atm, the variable volume chamber 415 may shrink. When the pressure within the steam management system 400 is greater than 1 atm, the variable volume chamber 415 may expand. The variable volume chamber 415 may allow the total volume of the steam management system 400 to expand to increase the total steam capacity, thereby allowing the system 400 to receive more steam 615 during transients. The expansion of the variable volume chamber 415 may reduce the pressure of the incoming steam 615 and promote condensation of the steam 615.

[0071] The steam management system 400 may include a pressure relief valve 460. The pressure relief valve 460 may be a safety device. The pressure relief valve 460 may open at a predetermined pressure threshold to prevent over-pressurization of the steam management system 400. The pressure relief valve 460 may be fluidly connected to the condensing chamber 430 via a discharge passage 462. In one embodiment, the pressure relief valve 460 may be configured to open when the pressure within the steam management system 400 is equal to or greater than about 0.15 psig. In another embodiment, the pressure relief valve 460 may be configured to open when the pressure within the steam management system 400 is equal to or greater than about 0.20 psig. In another embodiment, the pressure relief valve 460 may be configured to open when the pressure within the steam management system 400 is equal to or greater than about 0.25 psig.

[0072] The steam management system 400 may include a steam pump 420, such as Fig.13As shown. The steam pump 420 can be configured to be able to purge a mixture of air and dielectric vapor 615 from the immersion tank 201 to the condensation chamber 430. The steam pump 420 can be located upstream of the condensation chamber 430. The steam pump 420 can have an inlet and an outlet. The inlet of the steam pump 420 can be fluidly connected to the outlet of the variable volume chamber 415. The outlet of the steam pump 420 can be fluidly connected to the inlet 435 of the condensation chamber 430. The steam pump 420 is capable of reducing the pressure in the immersion tank 201 to below atmospheric pressure. The steam pump 420 can overcome the effects of gravity on fluid flow and allow the steam management system 400 to be positioned regardless of the height or orientation relative to the head space 206, thereby providing a convenient way to package the steam management system 400 in a confined space (such as a container 1005 ( Figure 1 and Figure 2 ) or utility box) may require greater design freedom.

[0073] The steam pump 420 can be used to preempt periods of expected elevated steam production. In one embodiment, upon detecting an increase in device power consumption that will result in elevated steam production, the valve 410 can be opened and the steam pump 420 can be enabled to purge steam 615 from the headspace 206, thereby pulling down the steam pressure within the tank 201 before an expected pressure rise. This approach can reduce the rate of pressure rise within the immersion tank 201 due to increased power consumption and steam production.

[0074] The steam management system 400 may be electrically controlled. The steam management system 400 may include an electronic control unit 480. The electronic control unit 480 may be configured to open or close the flow control valve 410 based on a signal received from the sensor 412 or other input signal. For example, the electronic control unit 480 may receive an input signal (e.g., a pressure signal) from the sensor 412 and send a command signal to the flow control (e.g., solenoid) valve 410 to open or close based on the input signal. The sensor 412 may be a pressure sensor configured to measure the pressure in the immersion tank 201. The sensor 412 may be configured to transmit a signal corresponding to the pressure in the immersion tank 201 to the electronic control unit 480. The signal may be transmitted via a wired or wireless connection.

[0075] The electronic control unit 480 may be configured to open or close the pressure relief valve 460 based on a signal received from a sensor or other input. The sensor 463 may be a pressure sensor configured to measure the pressure in the steam management system 400. The sensor 463 may be configured to transmit a signal corresponding to the pressure in the steam management system 400 to the electronic control unit 480. The signal may be transmitted via a wired or wireless connection.

[0076] The electronic control unit 480 may be configured to enable or disable the vapor pump 420 based on a signal received from the (eg, pressure) sensor 412. Fig.13 ). For example, in Fig.14 In the embodiment depicted in FIG. 4 , the electronic control unit 480 can enable the steam pump 420 and purge steam 615 from the head space 206 to reduce the tank pressure to below atmospheric pressure before initiating the cooling cycle. Reducing the pressure within the immersion tank 201 can reduce the boiling temperature of the fluid 620, which may be desirable in certain applications. Fig.14 In an embodiment, the tank pressure is pulled down to below atmospheric pressure and the threshold pressure setting of valve 410 is set below atmospheric pressure, thereby allowing the operating pressure of tank 201 to oscillate within a range including values ​​above and below atmospheric pressure. This approach can minimize the extent and duration of the tank pressure deviation from atmospheric pressure, thereby minimizing fluid losses due to pressure-induced diffusion or leakage. In another embodiment, the tank pressure can be pulled down to below atmospheric pressure and the threshold pressure setting of valve 410 can be set below atmospheric pressure, thereby allowing the operating pressure of tank 201 to oscillate within a negative pressure range. This approach may be desirable for reducing the boiling temperature of fluid 620.

[0077] In some embodiments, the apparatus 100 may include a water separation and filtration system 500 ( Figure 5 ).like Figure 5 , Fig.10 and Fig.11 As shown in , the water separation and filtration system 500 may include one or more of the following components: a water separator 565 and a filtration system 575. For the purpose of illustration and not limitation, the water separator 565 and the filtration system 575 may include a liquid pump 585, a drying filter 590, an impurity filter 580, etc.

[0078] For example, refer to Fig.10 In some embodiments, the apparatus 100 may include a water separator 565. The water separator 565 may include an inlet 440 and an outlet 574. The water separator 565 may receive condensed liquid from the condensation chamber 430. The water separator 565 may be configured to separate water 715 or other unwanted fluid from the dielectric fluid 620. The water separator 565 may capture the water 715 or other unwanted fluid and allow the dielectric fluid 620 to pass through. The water 715 or other unwanted fluid accumulated in the water separator 565 may be drained periodically. The amount of accumulated water 715 or other unwanted fluid may depend on the ambient air humidity, how well the apparatus is sealed, and how often the lid 225 of the immersion tank 201 is opened.

[0079] In one embodiment, the water separator 565 can be a gravity-based water separator. The density of the water 715 or other unwanted fluid can be less than the density of the dielectric liquid 620. Therefore, the captured water 715 or other unwanted fluid can settle on top of the dielectric liquid 620 within the water separator 565. The water 715 or other unwanted fluid can be periodically purged from the water separator 565 through the drain valve 573. The dehydrated dielectric liquid 620 can occupy the lower portion of the water separator 565. The dehydrated dielectric liquid 620 can be pumped out of the water separator 565 through the outlet 574 located in the lower portion of the water separator 565.

[0080] In an alternative embodiment, the water separator 565 can be a pump-based water separator. Fig.23 As shown, the auxiliary condenser 451 can extract heat from the steam 615 and the water vapor 710 and condense the steam 615 and the water vapor 710 in the condensation chamber 430. The liquid pump 576 can be connected in a fluid manner between the condensation chamber 430 and the water separator 565. Then, the condensate obtained from the condensed steam 615 and the water vapor 710 can accumulate in the flow chamber, so that the liquid level in the condensation chamber 430 rises. The liquid level sensor 577 operatively configured in the condensation chamber 430 can be configured to measure the liquid level. If the measured liquid level exceeds the preferred liquid level, the control device can be used to trigger the liquid pump 576 so that all or part of the liquid in the condensation chamber 430 will be pumped into the water separator 565. One advantage of this alternative embodiment is that, with the pump 576, the water separator 565 no longer needs to be arranged at a position with a sufficient gravitational potential difference with the condensation chamber 430.

[0081] In another embodiment, the water separator 565 may include an inclined perforated plate 566 in the container 564, such as Fig.11 As shown. The container 564 can be constructed and arranged to include an inlet 571, a dielectric fluid chamber 567, a dielectric fluid discharge port 569, a water chamber 568, and a drain 570. In some implementations, the water separator 565 can be configured to be able to separate the dielectric fluid 620 from the water 715 based on the characteristics of the liquid (such as, different surface tensions). For example, the typical surface tension of HFE-7100 is 13.6 dynes / cm, while the typical surface tension of water is 72 dynes / cm. Therefore, a mixture of dielectric fluid and water can flow through the inclined perforated plate 566, but due to the difference in surface tension, the dielectric fluid 620 with lower surface tension will flow into the fluid chamber 567 below the inclined perforated plate 566 through the perforations or holes 572, while the water with higher surface tension will flow to the end of the inclined perforated plate 566 and enter the water chamber 568. Although HFE-7100 is used as an example, this characteristic can be used for any dielectric fluid having a kinematic viscosity different from that of water.

[0082] The size of the perforations or holes 572 in the inclined perforated plate 566 can vary based on the surface tension of the dielectric fluid. For example, about 60-200 mesh size can effectively separate HFE-7100 from water. 80 mesh size means 80 holes are arranged in an area of ​​one square inch. 80 mesh size can include holes with a diameter of about 0.18mm. In another embodiment, the inclined perforated plate 566 can be replaced with a screen. The screen can be made of wire. The screen can have a mesh size of about 60-200.

[0083] The apparatus 100 may also include a filtration system 575. The filtration system 575 may include a dry filter 590, which, in certain variations, is fluidly connected to the liquid return channel 470 and disposed between the outlet 440 of the condensation chamber 430 and the inlet of the immersion tank 201. Preferably, the dry filter 590 may include a desiccant material.

[0084] The apparatus 100 may be constructed of metal, such as carbon steel. The immersion tank 201 may be constructed of metal with welds. Metal materials may be preferred over plastic materials because metal materials may effectively prevent moisture from being transferred from the surrounding environment to the dielectric fluid 620 in the tank 201. Minimizing moisture transfer to the dielectric fluid 620 is desirable for reducing the dehydration requirements of the water separator 565, and may also reduce the dehydration requirements of the desiccant material in the dry filter 590.

[0085] In some applications, the filtration system 575 may include a debris filter 580. The debris filter 580 may be fluidly connected to the liquid return channel 470 and disposed between the outlet of the dry filter 590 and the inlet of the immersion tank 201. The debris filter 580 may include activated carbon, charcoal, etc. The debris filter 580 may capture any debris or debris.

[0086] In some variations, the apparatus 100 may include a liquid return system. The liquid return system may be configured to enable the dielectric liquid 620 that has been condensed from the dielectric vapor to be returned to the immersion tank 201. The liquid return system may include a liquid pump 585. The liquid pump 585 may be fluidly connected to the liquid return channel 470 and disposed between the outlet 574 of the water separator 565 and the inlet to the immersion tank 201. For example, the liquid pump 585 may be located upstream of the filters 580, 590, or alternatively may be located downstream of the filters 580, 590.

[0087] Due to its efficient design, the two-phase immersion cooling device 100 may require significantly less dielectric fluid than competing designs that rely on relatively large internal or external reservoirs of supercooled fluid to function properly. Reducing fluid volume is desirable to reduce fluid costs, system weight, and system size. Minimizing size and weight may be particularly important in mobile and fixed applications where engineered flooring is not available to support the device 100.

[0088] In some embodiments, the steam management system 400 may only be needed periodically. For example, when the electronic device 800 is idle, operating below its maximum rated power, operating at a relatively constant power with little variation, or similar conditions, the steam management system 400 may not be needed until the power of the electronic device is increased. In other embodiments, the steam management system 400 may need to be used frequently, but may have sufficient cooling capacity to serve multiple immersion tanks 201 simultaneously. In either case, the central steam management system 400 may serve two or more immersion tanks 201, 201'. Fig.17 An embodiment of a two-phase immersion cooling device 1700 is shown, which has a central steam management system 400 that is fluidly connected to the first immersion tank assembly 200 and the second immersion tank assembly 200'. Using a central steam management system 400 may be cheaper than equipping each immersion tank 201, 201' with a separate steam management system 400. Using a central steam management system 400 may save floor space in the data center 2000 ( Figure 4 ). The use of a central steam management system 400 can reduce or simplify maintenance. Each immersion tank 201, 201' can be fluidly connected to the steam management system 400 through a corresponding steam supply channel 405, 405', and can be fluidly connected to the water separation and filtration assembly 500 through a liquid return channel 470.

[0089] The central steam management system 400 can monitor the tank pressure in each immersion tank 201, 201' (e.g., using one or more (e.g., pressure) sensors 412) and receive dielectric steam 615 from one tank 201, both tanks 201, 201', or neither tank 201, 201' as needed to maintain the tank pressure within an acceptable range. For example, when the first immersion tank pressure is at or above a first threshold pressure, the central steam management system 400 can receive steam from the first immersion tank 201. When the second immersion tank pressure is at or above a second threshold pressure, the central steam management system 400 can receive steam from the second immersion tank 201'.

[0090] Fig.18 A two-phase immersion cooling apparatus 1800 is shown, which is Fig.17The apparatus 1700 differs in that it includes steam pumps 420, 420', which are fluidly connected between the corresponding immersion tanks 201, 201' and the central steam management system 400. Each steam pump 420, 420' can be configured to remove a mixture of air and dielectric vapor from each immersion tank 201, 201' and force it into the condensation chamber 430. Each steam pump 420, 420' can be located upstream of the condensation chamber 430. Each steam pump 420, 420' can have an inlet and an outlet. The inlet of each steam pump 420, 420' can be fluidly connected to the outlet of the corresponding variable volume chamber 415, 415'. The outlet of each steam pump 420, 420' can be fluidly connected to the inlet 435 of the condensation chamber 430. Advantageously, each steam pump 420 is capable of reducing the pressure in the respective immersion tank to below atmospheric pressure.

[0091] In some embodiments, the steam management system 400 can be integrated into the two-phase immersion cooling device 100 and located in a common enclosure. In other embodiments, the steam management system 400 can be included in a separate steam processing device 900, such as Figure 19-22 As shown in , the steam handling device 900 is fluidly connected to one or more immersion tank assemblies 200, 200'. The steam handling device 900 can be retrofitted to an existing two-phase immersion cooling device 100 to improve steam management capabilities. For example, if the electronic devices 800 in the data center 2000 are upgraded and consume more electricity than the electronic devices 800 being replaced, the cooling capacity of the two-phase immersion cooling device 100 may need to be upgraded to manage the additional heat load. Alternatively, instead of replacing the device 100, a steam management system 400 can be added to the device 100 to manage higher steam production rates, allowing the existing immersion tank assemblies 200, 200' to be reused.

[0092] In some implementations, the steam treatment device 900 may include an enclosure 905, such as Fig.19As shown. The steam treatment device 900 may include a steam management system 400. The steam management system 400 may include a steam supply channel 405 having a steam supply inlet 401. The steam management system 400 may include a condensing chamber 430 having an inlet, an outlet, and an auxiliary condenser 451 in thermal communication with the internal volume of the condensing chamber 430. The steam supply channel 405 may fluidly connect the steam supply inlet 401 to an inlet 435 of the condensing chamber 430. The steam management system 400 may include a flow control valve 410 in the steam supply channel 405 between the steam supply inlet 401 and the inlet 435 of the condensing chamber 430. The steam management system 400 may include a liquid return channel 470, which fluidly connects the outlet 440 of the condensing chamber 430 to the liquid return outlet 471. The steam management system 400 may include a variable volume chamber 415, which is fluidly connected to the steam supply channel 405 between the steam supply inlet 401 and the inlet 435 of the condensing chamber 430. The steam management system 400 may further include a (e.g., pressure) sensor 412 located in the steam supply channel 405 and configured to detect the pressure within the immersion tank 201 when fluidly connected. The steam management system 400 may further include a pressure relief valve 460 fluidly connected to the condensation chamber 430.

[0093] Steam treatment equipment 900 may include a water separation and filtration assembly 500. Fig.10 As shown, the steam treatment device 900 may include a water separator 565 and / or a filtration system 575. The filtration system 575 may include one or more of a liquid pump 585, a drying filter 590, a foreign matter filter 580, and the like.

[0094] Fig.19 A steam processing apparatus 900 is shown having a single steam supply inlet 401 . Fig. 20 The steam treatment device 900 is shown as having two steam supply inlets 401, 401'. In other embodiments, the steam treatment device 900 may have more than two steam supply inlets 401, 401' to allow the device 900 to receive steam from more than two immersion tanks 201, 201'. In some embodiments, the steam treatment device 900 may receive steam from a group of immersion tanks. For example, the steam treatment device 900 may receive steam from a group of immersion tanks 201, 201' arranged in a plurality of tank assemblies 200, 200', such as Figure 2 or Figure 4 Having a central steam treatment device 900 may be more efficient and economical than having a steam treatment device 900 for each immersion tank 200 .

[0095] In some variations, the steam treatment apparatus 900 may include a steam pump 420 to allow the apparatus 900 to remove steam from the headspace 206 ( Figure 5 ) Actively remove dielectric vapor 615 and air 705 ( Figure 5 ). Fig.21 A steam processing apparatus 900 is shown having a single steam supply inlet 401 and a single steam pump 420 fluidly connected to a steam management system 400 . Fig. 22 A steam processing device 900 is shown having two steam supply inlets 401 , 401 ′ and respective steam pumps 420 , 420 ′ fluidly connected to respective steam supply channels 405 , 405 ′ of a steam management system 400 .

[0096] How to operate

[0097] Prior to use, the immersion tank 201 may be partially filled with a liquid dielectric fluid 620, such as Figure 5 As shown. The remainder of the immersion tank 201 can be filled with air 705 at approximately atmospheric pressure (e.g., 1 atm). The interface between the liquid dielectric fluid 620 and the air 705 can define a liquid pipeline 605. In some implementations, the fluid 620 can be non-toxic. In addition, in some variations, the fluid 620 can be non-conductive and non-hazardous to electronic devices.

[0098] Electronic devices 800 that need cooling (such as servers, switches, routers, firewalls, etc.) can be immersed in the fluid 620 in the immersion tank 201, such as Figure 5 As shown. For example, the electronic device 800 can be fully immersed and positioned below the liquid line 605. Power and communication cables (not shown) can extend from the electronic device 800 to connection locations outside the immersion tank 201. The cables can pass through the lid 225 or an opening in the tank wall. In another embodiment, the immersion tank 201 can include an integrated connector located within the tank 201 to simplify cable management. In some applications, the electronic device 800 can be arranged in a storage rack within the immersion tank 201.

[0099] The dielectric fluid 620 in the immersion tank 201 can initially be at about room temperature. After the electronic device 800 is immersed in the fluid and powered on, the device 800 can begin to generate waste heat as a byproduct of power consumption. The dielectric fluid 620 can absorb heat. If the heat flux from the device 800 is high enough, localized boiling of the dielectric fluid 620 can occur. The boiling can produce vapor bubbles that rise to the liquid line 605 via buoyancy and enter the headspace 206 of the immersion tank 201. The density of the dielectric vapor 615 can be greater than the density of the air 705, and therefore, a saturated vapor region 625 can form at the top of the liquid line 605, as shown in FIG. Figure 5 As shown. The vapor layer may be referred to as a vapor blanket 625. When the rate of vapor generation exceeds the rate of condensation, the depth of the vapor blanket 625 will grow. Eventually, the vapor level will approach the main condenser 235. The heat transfer from the vapor 615 to the main condenser 235 may promote the condensation of the vapor 615 into liquid 620. The condensed liquid 620 will then passively return to the liquid bath.

[0100] When the electronic device 800 is operating in a steady state, the rate of vapor generation and condensation through the main condenser 235 can reach a balance, thereby generating a relatively constant vapor pressure in the immersion tank 201. The vapor pressure of HFE-7100 can be calculated using the Antoine equation as shown below, where P is the vapor pressure and T is the temperature (in degrees Celsius):

[0101] oeLh 蒸汽 =22.415-3641.9(1 / (T+273))

[0102] As the power consumption of the electronic device 800 increases, the generation of waste heat and steam will also increase. If the power consumption continues to rise, at some point, the rate of steam generation may exceed the condensing capacity of the main condenser 235. Then, the steam pressure in the immersion tank 201 will begin to rise. When the pressure in the immersion tank 201 reaches a predetermined threshold, the valve 410 can be opened, such as Figure 6 As shown, vapor 615 will escape from the immersion tank 201 to the vapor management system 400. As the vapor management system 400 receives the dielectric fluid vapor 615, air 705, and water vapor 710 from the head space 206 of the immersion tank 201, the variable volume chamber 415 will expand, as shown in FIG. Figure 7 shown.

[0103] Figure 8 Graphs showing changes in the immersion tank 201 pressure and the device 800 power consumption over time are shown. In this embodiment, the electronic device 800 operates at idle or low power for a period of time. During this period, steam generation can be completely managed by the main condenser 235, and the steam management system 400 can remain in standby mode. Eventually, the device power consumption may increase. The increased power consumption may generate more waste heat, which in turn may generate more dielectric vapor 615. As steam generation increases, the condensing capacity of the main condenser 235 may eventually be exceeded. As steam 615, air 705, and water vapor 710 accumulate in the head space 206, the pressure of the immersion tank 201 begins to rise until it reaches a predetermined threshold pressure setting. When the predetermined threshold pressure setting is reached, as shown in FIG. Figure 6As shown, the flow control valve 410 can be actuated (e.g., by a signal from a (e.g., pressure) sensor 412) to allow steam 615, air 705, and water vapor 710 to escape from the immersion tank 201 and enter the steam management system 400. Actuation of the flow control valve 410 can cause the steam management system 400 to switch from a standby mode to an active mode and cause the chiller 446 to turn on or reduce its set point temperature to a level suitable for condensing the steam 615 and water vapor 710 allowed. As the steam 615, air 705, and water vapor 710 leave the immersion tank 201, the tank pressure will drop. Eventually, the tank pressure will drop below the threshold pressure setting of the flow control valve 410, resulting in the following. Figure 5 The flow control valve 410 is shown closed and captures the steam 615, air 705, and water vapor 710 received from the immersion tank 201 in the steam management system 400. The steam 615 and water vapor 710 can then be condensed in the condensation chamber 430, optionally dehydrated in the water separator 565, and further dried and filtered through the drying filter 590 and the impurity filter 580, respectively, and then returned to the immersion tank 201 as the dielectric liquid 620. The steam management system 400 can open and close the cycle as needed to receive and condense the steam 615 and water vapor 710 from the immersion tank 201 to maintain the pressure in the immersion tank 201 at or below the desired operating pressure.

[0104] In one embodiment, it may be desirable to predict a rise in steam production that would require activation of the steam management system 400. By monitoring the device power consumption, an increase in steam production may be predicted. When the device power consumption rises above a predetermined level, or alternatively rises above a predetermined level within a predetermined duration, the steam management system 400 may switch from standby mode to active mode. Switching from standby mode to active mode may involve activating the refrigerator 446 or lowering the set temperature of the refrigerator 446 to a level suitable for condensing the steam 615 and water vapor 710 allowed. This early activation may allow the refrigerator 446 ( Figure 6 ) There is enough time to reach the required operating temperature before the valve 410 opens and steam 615, air 705 and water vapor 710 are taken from the immersion tank 201. This approach can save energy when the steam management system 400 is in standby mode because the refrigerator temperature and refrigerator power consumption can be reduced.

[0105] In some cases, there may be an abnormal heat load within the immersion tank 201 that must be safely mitigated. For example, an abnormal heat load may occur if the electronic device 800 fails and exceeds the maximum power consumption rating. If this occurs, the heat and steam 615 and water vapor 710 generated may exceed the condensing capacity of the steam management system 400. In actual operation, when the tank pressure reaches the predetermined threshold setting of the flow control valve 410, the flow control valve 410 will open ( Figure 6 As steam 615, air 705, and water vapor 710 fill steam management system 400, bellows 415 can be configured to expand to store additional steam 615, air 705, and water vapor 710, such as Figure 7 After bellows 415 is fully expanded, if steam generation continues to increase, the pressure in steam management system 400 (e.g., as measured by (pressure) sensor 463) will continue to rise. To avoid mechanical failure due to overpressure, pressure relief valve 460 can be configured to be actuated when the pressure in steam management system 400 exceeds the maximum allowable pressure, such as Fig. 9 As shown. Steam 615, air 705, and water vapor 710 will then be exhausted to the surrounding environment, thereby reducing the pressure in the steam management system 400 and the immersion tank 201 and reducing the risk of mechanical failure. Although the flow of steam 615, air 705, and water vapor 710 to the surrounding environment results in fluid loss, which is undesirable, it is preferable to the safety risks associated with overpressure.

[0106] As used herein, the term "fluid" may refer to a substance in gaseous form, liquid form, or a two-phase mixture of gas and liquid. A fluid can undergo a phase change from liquid to vapor and vice versa. A liquid can form a free surface that is not formed by the container in which it is located, while a gas cannot.

[0107] As used herein, the term "vapor" may refer to a substance that is in a gas phase at a temperature below the critical temperature of the substance. Therefore, vapor can be condensed into a liquid by increasing the pressure without reducing the temperature.

[0108] As used herein, the term "two-phase mixture" may refer to the coexistence of a vapor phase of a substance with a liquid phase of the substance. When this occurs, the partial pressure of the gas may be equal to the vapor pressure of the liquid.

[0109] The dielectric fluid 620 may be selected for use in an immersion cooling device based on various factors, including operating pressure, temperature, boiling point, cost, or safety regulations governing the installation (e.g., regulations set forth in ASHRAE Standard 15 regarding the amount of fluid allowed per volume of occupied building space).

[0110] In some cases, the choice of fluid may be influenced by desired dielectric properties, desired boiling point, or compatibility with materials used to make the immersion cooling system 100 and the electronic device 800 to be cooled. For example, the fluid may be selected to ensure little or no permeability through system components and no deleterious effects on device 800 components.

[0111] Dielectric fluid 620, such as hydrofluorocarbon (HFC) or hydrofluoroether (HFE), can be used as the fluid in immersion cooling device 100. Unlike water, dielectric fluid can be used in direct contact with electronic devices 800 (such as microprocessor 801, memory modules, power inverters, etc.) without the risk of shorting electrical connections.

[0112] Non-limiting examples of dielectric fluids include 1,1,1,3,3-pentafluoropropane (known as R-245fa), hydrofluoroether (HFE), 1-methoxyheptafluoropropane (known as HFE-7000), methoxy non-fluorobutane (known as HFE-7100). Hydrofluoroethers including HFE-7000, HFE-7100, HFE-7200, HFE-7300, HFE-7500 and HFE-7600 are marketed as NOVEC engineered fluids by 3M Company in Mapleton, Minnesota. FC-40, FC-43, FC-72, FC-84, FC-770, FC-3283 and FC-3284 are commercially available as fluorine inert electronic liquids also from 3M Company.

[0113] The boiling point of NOVEC 7100 is 61°C, the molecular weight is 250g / mol, the critical temperature is 195°C, the critical pressure is 2.23MPa, the vapor pressure is 27kPa, the heat of vaporization is 112kJ / kg, and the liquid density is 1510kg / m 3 , specific heat of 1183 J / kg-K, thermal conductivity of 0.069 W / mK, and dielectric strength of about 40 kV at a 0.1 inch gap. NOVEC 7100 is suitable for certain electronic devices 800, such as power electronic devices 800 that generate high heat loads and can operate safely at temperatures above about 80°C.

[0114] The NOVEC 7100 can be used to cool the microprocessor 801, which has a preferred operating core temperature of about 60-70° C. When the microprocessor 801 is idle and the surface temperature is below 61° C., the supercooled NOVEC 7100 near the microprocessor 801 may not experience local boiling. When the microprocessor 801 is fully utilized and the surface temperature is at or above 61° C., the NOVEC 7100 may experience severe local boiling and steam generation near the microprocessor.

[0115] NOVEC 649 engineered fluid is provided by 3M. It is a fluoroketone fluid (C6-fluoroketone) with low global warming potential (GWP). Its boiling point is 49°C, thermal conductivity is 0.059, molecular weight is 316g / mol, critical temperature is 169°C, critical pressure is 1.88MPa, vapor pressure is 40kPa, heat of vaporization is 88kJ / kg, and liquid density is 1600kg / m 3 .

[0116] The NOVEC 649 can be used to cool the microprocessor 801, which has a preferred operating core temperature of about 60-70° C. When the microprocessor 801 is idle and the surface temperature is below 49° C., the supercooled NOVEC 649 near the microprocessor 801 may not experience local boiling. When the microprocessor 801 is fully utilized and the surface temperature is 49° C. or above, the NOVEC 649 may experience severe local boiling and steam generation near the microprocessor 801.

[0117] Elements and method steps described herein may be used in any combination, whether or not explicitly described.All combinations of method steps described herein may be performed in any order, unless otherwise specified or clearly implied to the contrary by the context in which the referenced combination is located.

[0118] As used herein, the singular form "a," "an," and "the" include plural referents unless the content clearly dictates otherwise.

[0119] The unit "psig" used herein represents gauge pressure in pounds per square inch. Positive values ​​indicate pressures above atmospheric pressure. Negative values ​​indicate pressures below atmospheric pressure.

[0120] As used herein, the term "fluidically connected" may describe a first component being directly connected to a second component or a first component being indirectly connected to a second component through one or more intermediate components, wherein a fluid in gaseous form, liquid form, or a two-phase mixture may pass from the first component to the second component without escaping to the atmosphere.

[0121] The numerical ranges used herein are intended to include every value and subset of values ​​contained within the range, whether or not explicitly disclosed. In addition, these numerical ranges should be interpreted as providing support for claims for any value or subset of values ​​within the range. For example, a disclosure of 1-10 should be interpreted as supporting ranges from 2 to 8, from 3 to 7, from 5 to 6, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, etc.

[0122] The methods and compositions of the present invention may comprise, consist of, or consist essentially of the structural elements and process step limitations described herein, as well as any additional or optional steps, components, or limitations described herein or otherwise useful in the art.

[0123] It will be understood that the invention is not limited to the particular construction and arrangement of parts illustrated and described herein, but encompasses modifications thereof within the scope of the claims.

[0124] The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the claims to the disclosed embodiments. Other modifications and variations are possible in light of the above teachings. The embodiments chosen and described are intended to explain the principles of the invention and its practical application, so that others skilled in the art can best utilize the invention in various embodiments and various modifications suitable for the particular use contemplated. It is intended that the claims be interpreted to include other alternative embodiments of the invention unless limited by the prior art.

Claims

1. A two-phase immersion cooling device comprising: An immersion tank assembly, the immersion tank assembly comprising: at least one immersion tank, each immersion tank forming an interior volume and comprising: upper part; the lower portion; and a main condenser in thermal communication with the interior volume of the immersion tank; and A steam management system fluidly connected to the immersion tank assembly, the steam management system comprising: a condensation chamber forming an interior volume and comprising: Entrance; export; and an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a steam supply channel fluidly connecting an upper portion of the immersion tank to an inlet of the condensation chamber; a valve disposed in the steam supply passage between the upper portion of the immersion tank and the inlet of the condensation chamber; and A liquid return passage fluidly connects the outlet of the condensation chamber to the immersion tank assembly.

2. The two-phase immersion cooling apparatus of claim 1 , further comprising a variable volume chamber fluidly connected to the steam supply channel and disposed between an upper portion of the immersion tank assembly and an inlet of the condensation chamber.

3. A two-phase immersion cooling apparatus according to claim 1 or claim 2, further comprising a pressure relief valve fluidly connected to the condensation chamber.

4. The two-phase immersion cooling apparatus of any one of the preceding claims, further comprising a sensor to detect pressure within the immersion tank assembly, the sensor being located in at least one of the immersion tank assembly or the steam supply channel.

5. The two-phase immersion cooling apparatus according to any one of the preceding claims, further comprising: a drain passage fluidly connected to the condensation chamber; a pressure relief valve fluidly connected in the discharge passage; as well as A sensor is used to detect the pressure in the steam management system and is located in the steam management system.

6. A two-phase immersion cooling apparatus according to any one of the preceding claims, further comprising a water separator fluidly connected to the liquid return passage between the outlet of the condensation chamber and the inlet to the immersion tank assembly.

7. A two-phase immersion cooling apparatus according to any one of the preceding claims, further comprising a liquid pump fluidly connected to the liquid return passage and disposed between the outlet of the condensation chamber and the inlet to the immersion tank assembly.

8. A two-phase immersion cooling apparatus according to any one of the preceding claims, further comprising a filter drier fluidly connected to the liquid return passage and disposed between the outlet of the condensation chamber and the inlet to the immersion tank assembly.

9. The two-phase immersion cooling apparatus according to any one of the preceding claims, further comprising a debris filter fluidly connected to the liquid return passage and disposed between the outlet of the condensation chamber and the inlet to the immersion tank assembly.

10. The two-phase immersion cooling apparatus according to any one of the preceding claims, further comprising a steam pump fluidly connected to the steam supply channel and arranged between the upper part of the immersion tank and the inlet of the condensation chamber.

11. A two-phase immersion cooling device comprising: An immersion tank assembly, the immersion tank assembly comprising: at least one immersion tank, each immersion tank forming an interior volume and comprising: upper part; the lower portion; and a main condenser in thermal communication with the interior volume; and A steam management system fluidly connected to the immersion tank assembly, the steam management system comprising: a condensation chamber forming an interior volume and comprising: Entrance; export, and an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a steam supply channel fluidly connecting an upper portion of the immersion tank to an inlet of the condensation chamber; a valve disposed in the steam supply passage between the upper portion of the immersion tank and the inlet of the condensation chamber; a liquid return passage fluidly connecting an outlet of the condensation chamber to an inlet to the immersion tank assembly; a sensor configured to detect pressure within the immersion tank assembly and to generate and transmit a signal based on the measured pressure; and An electronic control unit is configured to receive a signal from the sensor and send a command signal to the valve.

12. The two-phase immersion cooling device according to claim 11, wherein: The sensor is disposed in at least one of the immersion tank assembly or a steam supply passage between the valve and the immersion tank assembly.

13. The two-phase immersion cooling device according to claim 11 or claim 12, wherein: The volume of the condensation chamber is at least 10% of the headspace volume of the immersion tank.

14. The two-phase immersion cooling device according to any one of claims 11 to 13, wherein: The condensing chamber also includes a refrigerator that is fluidly connected to the auxiliary condenser.

15. The two-phase immersion cooling apparatus according to any one of claims 11 to 14, further comprising a heat exchanger fluidly connected to the main condenser.

16. A method for immersion cooling a heat generating device, the method comprising: A two-phase immersion cooling device is provided, the two-phase immersion cooling device comprising: An immersion tank assembly, the immersion tank assembly comprising: at least one immersion tank, each immersion tank forming an interior volume and comprising: upper part; the lower portion; and a main condenser in thermal communication with the interior volume of the immersion tank; and A steam management system fluidly connected to the immersion tank assembly, the steam management system comprising: a condensation chamber forming an interior volume and comprising: Entrance; export; and an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a steam supply channel fluidly connecting an upper portion of the immersion tank to an inlet of the condensation chamber; a valve provided in the steam supply passage between the upper portion of the immersion tank and the inlet of the condensation chamber; and a liquid return passage fluidly connecting an outlet of the condensation chamber to the immersion tank assembly; Detect the pressure in the immersion tank; At least one of the following: opening the valve when the measured pressure in the immersion tank assembly is greater than a predetermined threshold setting such that dielectric vapor and other gases from the immersion tank assembly are allowed to enter the condensation chamber; or closing the valve when the measured pressure in the immersion tank assembly is less than a predetermined threshold setting; Condensing dielectric vapor and other gases to a liquid state in a condensation chamber; and The condensed dielectric liquid is returned to the immersion tank assembly through the liquid return passage.

17. The method of claim 16, further comprising circulating a coolant through the primary condenser, the coolant having a temperature greater than or equal to ambient air temperature.

18. The method according to claim 16 or claim 17, further comprising: circulating a first coolant through the main condenser; and circulating a second coolant through the auxiliary condenser, Wherein, the temperature of the first coolant is greater than the temperature of the second coolant.

19. The method of claim 16, claim 17 or claim 18, further comprising: providing a steam pump fluidly connected to the steam supply passage and disposed between the immersion tank assembly and the inlet of the condensation chamber; and The steam pump is operated while the valve is open to purge gas from the head space of the immersion tank and reduce the pressure within the immersion tank to below atmospheric pressure.

20. The method according to any one of claims 16 to 19, wherein: The predetermined threshold is set between -0.9 psig and 0.9 psig.

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