Two-Phase Immersion Chiller with Active Vapor Management

Abstract

A two-phase immersion cooling apparatus may include an immersion tank with a main condenser in thermal communication with the 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 production by removing vapor and other gases from the headspace of the immersion tank, condensing the vapor into a liquid, and returning the liquid to the immersion tank.

Description

[Technical Field]

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

[0002] A data center houses information technology (IT) equipment for the purposes of 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] During use, IT equipment consumes electricity and generates heat as a by-product. Data centers containing thousands of servers require dedicated IT cooling systems to manage the generated heat. The heat must be captured and removed from the data center. If the heat is not removed, the ambient temperature within the data center can exceed acceptable thresholds, resulting in temperature-induced performance limitations of electronic devices (e.g., microprocessors).

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

[0005] Electricity usage in a data center comes from a variety of systems, including IT equipment, air management systems, mechanical systems, electrical systems (e.g., power conditioning systems), and cooling systems for the 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 utilize precision air conditioning systems for IT cooling. Precision air conditioners, like residential air conditioners, utilize a vapor compression cycle. While air conditioning technology is well suited to comfort cooling office spaces, it is less suited to cooling the thousands of relatively small, hot devices that are distributed throughout large data centers. Air has a relatively low thermal capacity, and large volumes of air must be moved and conditioned to cool IT equipment. As a result, air conditioners experience poor thermodynamic efficiency and therefore high operating costs. To reduce operating costs, there is a need to cool servers more efficiently. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, advances are needed to improve the efficiency, performance, reliability and sustainability of IT cooling systems. [Means for solving the problem]

[0008] In a first aspect, the present invention relates to a two-phase immersion cooling apparatus. In some embodiments, the two-phase immersion cooling apparatus includes an immersion tank assembly including one or more immersion tanks each forming an interior volume, and a vapor management system fluidly 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 interior volume of the immersion tank. The vapor management system may include a condensing chamber forming an interior volume and including an inlet, an outlet, and an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a vapor supply channel fluidly connecting the upper portion of the immersion tank to the inlet of the condensing chamber; a valve in the vapor supply channel between the upper portion of the immersion tank and the inlet of the condensing chamber; and a liquid return channel fluidly connecting the outlet of the condensing chamber to the immersion tank assembly.

[0009] In some implementations, the two-phase immersion cooling apparatus may also include one or more of the following: a variable volume chamber fluidly connected to the steam supply passage and disposed between an upper portion of the immersion tank assembly and an inlet of the condensing chamber; a pressure relief valve fluidly connected to the condensing chamber; a sensor detecting pressure within the immersion tank assembly, the sensor located in the immersion tank assembly and / or in the steam supply passage; a discharge passage fluidly connected to the condensing chamber; a pressure relief valve fluidly connected to the discharge passage; a sensor located in the steam management system detecting pressure within the steam management system; a water separator fluidly connected to a liquid return passage between an outlet of the condensing chamber and an inlet to the immersion tank assembly; a liquid pump fluidly connected to the liquid return passage 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 passage 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 passage 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 passage and disposed between an upper portion of the immersion tank and an inlet to the condensing chamber.

[0010] In a second aspect, the present invention relates to a two-phase immersion cooling apparatus. In some embodiments, the two-phase immersion cooling apparatus includes an immersion tank assembly including one or more immersion tanks each forming an internal volume, and a steam management system fluidly 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. The steam management system may include a condensing chamber forming the internal volume and having an inlet, an outlet, and an auxiliary condenser in thermal communication with the internal volume of the condensing chamber; a steam supply passage fluidly connecting the upper portion of the immersion tank to the inlet of the condensing chamber; a valve in the steam supply passage between the upper portion of the immersion tank and the inlet of the condensing chamber; a liquid return passage fluidly connecting the outlet of the condensing chamber to the inlet to the immersion tank assembly; a sensor configured to detect pressure in the immersion tank assembly and generate and transmit a signal based on the measured pressure; and an electronic control unit configured to receive a signal from the sensor and send a command signal to the valve.

[0011] In some implementations, the sensor may be located in the immersion tank assembly and / or the steam supply flow path between the valve and the immersion tank assembly. In some variations, the condensation chamber may have a volume at least 10% of the headspace volume of the immersion tank. In some applications, the condensation chamber may also include a chiller fluidly connected to the auxiliary condenser. In some embodiments, the apparatus may also include a heat exchanger fluidly 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 apparatus, detecting a pressure in an immersion tank, and at least one of opening a valve when the measured pressure at the immersion tank assembly is greater than a predetermined threshold setting (e.g., between −0.9 psig and 0.9 psig) so that dielectric vapor and other gases from the immersion tank assembly are admitted to a condensing chamber or closing the valve when the measured pressure at the immersion tank assembly is less than the predetermined threshold setting, condensing the dielectric vapor and other gases to a liquid state in the condensing chamber, and returning the condensed dielectric liquid to the immersion tank assembly through a liquid return flow path.

[0013] In some implementations, a two-phase immersion cooling apparatus may include an immersion tank assembly including one or more immersion tanks each defining an interior volume, and a vapor management system fluidly 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 interior volume of the immersion tank, and the vapor management system may include a condensing chamber defining an interior volume and including an inlet, an outlet, and an auxiliary condenser in thermal communication with the interior volume of the condensing chamber, a vapor supply passage fluidly connecting the upper portion of the immersion tank to the inlet of the condensing chamber, a valve in the vapor supply passage between the upper portion of the immersion tank and the inlet of the condensing chamber, and a liquid return passage fluidly connecting the outlet of the condensing chamber to the immersion tank assembly.

[0014] In some variations, the method may also include circulating a coolant through the main condenser, the coolant having a temperature equal to or greater than ambient temperature, and / or circulating a first coolant through the main condenser and a second coolant through the auxiliary condenser, the temperature of the first coolant being greater than the temperature of the second coolant.

[0015] In some implementations, the method may also include providing a vapor pump fluidly connected to the vapor supply passage and disposed between the immersion tank assembly and the inlet of the condensation chamber, and operating the vapor pump while the valve is open to purge gas from the headspace of the immersion tank and reduce the pressure in the immersion tank below atmospheric pressure. [Brief explanation of the drawings]

[0016] [Figure 1] 1 illustrates a perspective view of a modular data center according to some embodiments of the present invention. [Figure 2] 2 illustrates a partial cutaway view of the modular data center of FIG. 1 exposing multiple immersion cooling bath assemblies within the vessel in accordance with some embodiments of the present invention. [Figure 3] FIG. 2 illustrates a perspective view of an immersion cooling bath assembly, according to some embodiments of the present invention. [Figure 4] FIG. 1 illustrates a perspective view of multiple immersion cooling tank assemblies disposed in a conventional data center in accordance with some embodiments of the present invention. [Figure 5] FIG. 1 shows a schematic diagram of a two-phase immersion cooling apparatus with a steam management system, in accordance with some embodiments of the present invention. [Figure 6] 6 illustrates the device of FIG. 5 with the flow control valve open, according to some embodiments of the present invention. [Figure 7] 6 illustrates the device of FIG. 5 with the flow control valve open and the bellows extended, according to some embodiments of the present invention. [Figure 8] FIG. 10 shows plots of immersion bath pressure and electronic device power consumption versus time, according to some embodiments of the present invention. [Figure 9]6 illustrates the apparatus of FIG. 5 with the pressure relief valve open, according to some embodiments of the present invention. [Figure 10] FIG. 1 illustrates a gravity-based water separator and filtration assembly according to some embodiments of the present invention. [Figure 11] 10A-10C illustrate alternative embodiments of a water separator, according to some embodiments of the present invention. [Figure 12] FIG. 1 illustrates a chiller and an auxiliary condenser according to some embodiments of the present invention. [Figure 13] 6 illustrates the apparatus of FIG. 5 with a vapor pump included in the vapor management system, according to some embodiments of the present invention. [Figure 14] FIG. 10 shows plots of immersion bath pressure and electronic device power consumption versus time when the bath pressure is reduced below atmospheric pressure before powering the electronic device, in accordance with some embodiments of the present invention. [Figure 15] FIG. 1 illustrates a prior art immersion cooling system with a main condenser. [Figure 16] FIG. 1 illustrates an immersion cooling system with a main condenser and a freeboard condenser according to the prior art. [Figure 17] FIG. 1 illustrates an embodiment of a two-phase immersion cooling apparatus with two immersion tanks fluidly connected to a central steam management system, in accordance with some embodiments of the present invention. [Figure 18] FIG. 18 illustrates the apparatus of FIG. 17 with a steam pump fluidly connected between each immersion tank and a central steam management system, according to some embodiments of the present invention. [Figure 19] 1 illustrates a vapor treatment device according to some embodiments of the present invention. [Figure 20] FIG. 1 illustrates a steam treatment device with two steam supply inlets, according to some embodiments of the present invention. [Figure 21] 1 illustrates a steam treatment device with a steam pump, according to some embodiments of the present invention. [Figure 22]FIG. 1 illustrates a steam treatment device with two steam supply inlets and two steam pumps, according to some embodiments of the present invention. [Figure 23] 6 illustrates the apparatus of FIG. 5 with a liquid level sensor included in the vapor management system and a liquid pump included in the water separator and filtration assembly, according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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, electronic devices are immersed in a dielectric fluid. Waste heat from the electronic devices is transferred to the fluid and then rejected outside the data center. Because the waste heat is not released into the data center atmosphere, precision air conditioning systems are generally not required.

[0018] Immersion cooling systems may utilize single-phase or two-phase technology. In single-phase immersion cooling systems, electronic devices are immersed in a fluid, such as mineral oil. Waste heat from the electronic devices is transferred to the fluid, warming it. The warmed fluid is pumped from the immersion cooling system to a heat rejection system, such as an evaporative cooling tower, dry chiller, or chilled water loop, which captures the waste heat from the fluid and rejects the heat outside the data center.

[0019] A drawback of single-phase immersion cooling technology is that mineral oil acts as a solvent and, over time, can remove identifying information from motherboards, processors, and other components. For example, product labels (e.g., stickers containing serial numbers and barcodes) and other markings (e.g., screen-printed information and model numbers on capacitors and other devices) can dissolve and run off due to the continuous flow of mineral oil on the device surface. As labels and ink run off the server, the mineral oil can become contaminated and need to be replaced, resulting in expense and periodic downtime. Another drawback of single-phase immersion cooling is that the server cannot be inspected immediately after being removed from the bath. Typically, the server must be removed from the bath and allowed to drip dry for several hours before inspection. 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 particulates) on sensitive circuitry, increasing the risk of short circuits and failures.

[0020] In a two-phase immersion cooling system, electronic devices are immersed in a fluid, such as a hydrofluoroether, in a bath. Because the fluid evaporates quickly and leaves no residue, two-phase systems do not suffer from the drawbacks of single-phase, mineral oil-based systems. During use, waste heat from the electronic devices is absorbed by the fluid, leading to localized vaporization of the fluid. Vapor rises into the headspace of the bath and is condensed by a condenser. 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 rejection system, such as an evaporative cooling tower, dry chiller, or chilled water loop, which captures the waste heat from the fluid and rejects the heat outside the data center.

[0021] Two-phase immersion cooling systems take advantage of phase-change heat transfer, making them more efficient and capable than single-phase immersion cooling systems for cooling high-heat-flux electronic devices, such as high-performance computing (HPC) servers with multiple graphics processing units (GPUs). However, challenges accompany the benefits of phase-change heat transfer. In practice, maintaining vapor within the system has proven difficult with prior art two-phase systems. Over time, existing two-phase immersion cooling systems inevitably experience fluid loss to the environment. The lost fluid can be costly to replenish on a circulatory basis. Examples of prior art two-phase cooling systems, as well as their modes of fluid loss and other drawbacks, are described below.

[0022] FIG. 15 illustrates a prior art example of a basic two-phase immersion cooling apparatus 1500. The apparatus 1500 includes an immersion bath 201 partially filled with a dielectric fluid 620 in the liquid phase. The apparatus includes a condenser 235 mounted in the headspace of the bath 201. An electronic device 800 is immersed in the dielectric fluid. The electronic device may be a server including one or more microprocessors 801. The bath 201 is closed by a lid 225. When powered and functioning, the electronic device 800 generates heat. The heat is transferred to the dielectric fluid 620, causing a portion of the fluid to boil and form a dielectric vapor 615. The vapor 615 rises through the bath of dielectric liquid 620 and enters the headspace of the bath 201. When the vapor 615 contacts the condenser 235, it condenses into a liquid and is passively recycled back into the liquid bath, thereby completing a cycle of evaporation, condensation, precipitation, and recovery. During operation, boiling of the relatively dense dielectric fluid 620 produces a relatively low-density vapor 615, which expands and enters the headspace occupied by non-condensable gases. Because the dielectric fluid 620 occupies more volume as a vapor than as a liquid, the vessel pressure increases as more vapor 615 is produced and enters the headspace. To prevent the vessel pressure from reaching unsafe levels, a pressure relief valve 460 is provided in the vessel 201 and opens when the pressure exceeds a predetermined threshold. In response to actuation of the pressure relief valve 460, the dielectric vapor 615 is released from the vessel 201 and lost to the environment. Over time, the periodic valve actuation and fluid loss depletes the fluid 620, necessitating replenishment.

[0023] In a variation of the example illustrated in FIG. 15 , the two-phase immersion cooling apparatus 1500 can be configured to maintain a bath pressure close to ambient pressure (e.g., 1 atmosphere) at all times. Operating at or near ambient pressure would be desirable to minimize fluid losses caused by leakage or diffusion through system joints or materials, respectively. As the heat load from the electronic device 800 increases, the dielectric vapor generation rate increases, and pressure builds up within the bath 201. To avoid pressure buildup, the pressure relief valve 460 may be activated whenever the bath pressure exceeds ambient pressure. During periods of intensive computing, this may lead to frequent venting of the vapor 615 to the environment. During periods of inactivity, the heat load from the device 800 will decrease, and the vapor generation rate will decrease or even cease. Any remaining vapor 615 is condensed by the condenser 235, which subsequently further cools the air in the headspace, causing the bath pressure to drop below ambient pressure. To relieve the negative pressure within the vessel 201, a pressure relief valve 460 may be opened to allow ambient air to enter the vessel 201. Over time, this cyclical gas exchange leads to fluid loss.

[0024] 15, a two-phase immersion cooling apparatus 1500 can include a high-capacity condenser 235 with a cooling capacity that exceeds the maximum heat load of the electronic device 800. The condenser 235 can operate at a temperature significantly below the vapor temperature of the dielectric fluid 620, thereby ensuring that the vapor 615 is condensed promptly, thereby avoiding overpressure due to vapor buildup. While this approach reduces fluid losses, the condenser 235 is large and energy inefficient, making it costly and impractical for large-scale data center applications.

[0025] In another variation of the example illustrated in FIG. 15 , the two-phase immersion cooling system 1500 can be sealed. The vessel 201 can be a pressure vessel, capable of withstanding high positive or negative pressures without risk of failure. Unfortunately, pressure vessels are expensive to build and maintain. Due to product liability, the effect of high-pressure operation on unique server models requires pre-use evaluation and approval, leading to ongoing review and liability exposure. High operating pressures can promote diffusional loss of fluids and accelerate aging of gaskets and other system components. With sealed systems, routine server maintenance requires shutting down the cooling system and opening the lid to access the server, which is time-consuming. For these reasons, a sealed vessel 201 is not a practical option for most data centers, especially those with high uptime requirements.

[0026] FIG. 16 illustrates a second prior art example of a two-phase immersion cooling apparatus 1600. The apparatus 1600 includes an immersion tank 201 partially filled with a dielectric fluid 620 in the 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 closed by a lid 225. The apparatus 1600 may include two condensers. For example, the apparatus 1600 may include a main condenser 235 and a freeboard condenser 250 mounted within the immersion tank 201. The main condenser 235 may be located above the liquid line 605 within the headspace of the tank 201. The freeboard condenser 250 may be located a distance above the main condenser 235 within the headspace 206. In one example, the main condenser 235 may operate at a temperature of approximately 5°C to 15°C. The freeboard condenser 250 may operate at low temperatures of approximately −28° C. to −2° C. The apparatus 1600 has a high freeboard ratio, which is defined as the distance measured from the top of the main condenser 235 to the underside of the lid 225 divided by the interior width of the immersion tank 201.

[0027] During steady-state operation of the apparatus 1600, vapor 615 is generated as heat from the electronic device 800 vaporizes the fluid 620 in the vessel 201. Because the vapor 615 is heavier than the air 705, a first region 1605 containing saturated vapor 615 may settle above the liquid line 605. A second region 1610 containing mixed vapor 615 and air 705 may form above the saturated vapor 615. A third region 1615 containing mostly air 705 may form above the mixture of vapor 615 and air 705. The saturated vapor region 1605 may be located between the liquid line 605 and the main condenser 235. The mixed vapor and air region 1610 may be located between the main condenser 235 and the freeboard condenser 250. The third region 1615 containing mostly air 705 may be located between the freeboard condenser 250 and the lid 225. The main condenser 235 may be appropriately sized to condense a majority of the steam 615 produced during steady-state operation. The freeboard condenser 250 may condense the steam 615 that rises from the main condenser 235 and enters the second region 1610. During steady-state operation, an equilibrium of steam production and condensation may exist.

[0028] During periods of high microprocessor 801 utilization, more power is consumed by device 800 and more heat is generated, leading to higher vapor production rates. As the amount of vapor 615 in headspace 206 increases, the depth of saturated vapor region 1605 increases. Freeboard condenser 250 is maintained at a much lower temperature than main condenser 235 and can effectively condense the vapor 615 that reaches it.

[0029] While effective, the apparatus 1600 in FIG. 16 has certain drawbacks. First, the freeboard condenser 250 requires the chiller to operate continuously to maintain an adequately chilled temperature, making the apparatus 1600 inefficient. Second, the apparatus 1600 is not compact or user-friendly. To be effective, the apparatus 1600 must have a high freeboard ratio, requiring a relatively tall vessel 201. While a tall vessel 201 may be acceptable for a traditional data center with high ceilings and hoist or ladder access for inserting and removing electronic equipment from the vessel 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 with height restrictions and minimal headroom (e.g., a shipping container 1005 (FIGS. 1 and 2) or a utility enclosure). In addition to these practical limitations, the cooling system 1600 in FIG. 16 may also experience fluid loss in a similar manner as the cooling system 1500 shown in FIG. 15 and described above.

[0030] In view of the above examples, it would be desirable to provide a two-phase immersion cooling system that is compact, energy efficient, inexpensive, and incurs minimal fluid loss to the environment.

[0031] Two-Phase Immersion Chiller with Active Vapor Management Figure 5 illustrates one embodiment of a two-phase immersion chiller 100 with active vapor management in accordance with an embodiment of the present invention. The two-phase immersion chiller 100 may be used in a variety of applications, ranging from a modular data center 1000, as illustrated in Figure 1, to a traditional data center 2000, as illustrated in Figure 4. In the embodiment of Figure 1, the immersion chiller 100 may be disposed within a vessel 1005 (Figures 1 and 2) and fluidly connected to an external heat rejection system 240 mounted on the vessel 1005.

[0032] The apparatus 100 may include an immersion tank assembly 200. The immersion tank assembly 200 may include an immersion tank 201 that is selectively sealable with a lid 225 (FIG. 3). The immersion tank 201 may be compact vertically, allowing it to be placed in a limited space, such as a shipping container 1005 or a utility enclosure associated with modular or edge data center applications. The immersion tank 201 may have a height that is less than the length or width of the tank 201. The immersion tank 201 may have a height that is less than the length and less than the width of the tank 201.

[0033] 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 a 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 formed between gas (e.g., air and dielectric vapor) in the headspace and the 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 electrical insulating layer 230 on its inner 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, a switch, or power electronics). When closed, the lid 225 may close the opening 220 to prevent vapor loss. The lid 225 may seal (eg, hermetically) the opening 220 .

[0034] The immersion bath 201 may be partially filled with a (e.g., dielectric) fluid 620. The fluid 620 may be selected to have a boiling point lower than the operating temperature of a heat-generating electronic device 800, such as a microprocessor 801, or may be prepared by mixing two or more fluids. When the electronic device 800 is operating, the fluid 620 in contact with the device 800 may locally boil and generate vapor 615. The vapor 615 may rise through the fluid bath into the headspace 206 of the immersion bath 201. The vapor 615 may settle above the liquid line 605, forming a blanket 625 of saturated vapor.

[0035] The immersion tank assembly 200 may include a main condenser 235. The main condenser 235 may be located in the headspace 206 of the tank 201. The main condenser 235 may condense the vapor 615 within the immersion tank 201. In some implementations, the main condenser 235 may be a cooling coil, more specifically, a cooling coil that receives a coolant such as chilled water, a water-glycol mixture, a refrigerant, or the like, from a heat rejection system 240, such as an evaporative cooling tower, a dry chiller, or a chilled water loop. The heat rejection system 240 may include a coolant pump 245, as illustrated in FIGS. 1 and 5 . The coolant pump 245 may circulate the coolant through the main condenser 235 and the heat rejection system 240.

[0036] To minimize energy consumption, the main condenser 235 may operate at or slightly above room temperature. In one embodiment, the main condenser 235 may receive and circulate coolant at a temperature of approximately 33°C when the ambient temperature is 30°C. In another embodiment, the main condenser 235 may receive and circulate coolant at a temperature of approximately 25°C to 40°C. In yet another embodiment, the main condenser 235 may receive and circulate coolant at a temperature of approximately 30°C to 36°C. In yet another embodiment, the main condenser 235 may receive and circulate coolant at a temperature of approximately 0 to 10 degrees above ambient temperature. In yet another embodiment, the main condenser 235 may receive and circulate coolant at a temperature of approximately 0 to 15 degrees above ambient temperature.

[0037] Apparatus 100 may include a vapor management system 400. Vapor management system 400 may be fluidly connected to immersion tank 201. Vapor management system 400 may receive vapor 615 from immersion tank 201 when necessary to avoid overpressurization of tank 201, condense vapor 615 into liquid 620, and return liquid 620 to immersion tank 201 for reuse. Vapor management system 400 may be located at least partially outside headspace 206 of immersion tank 201.

[0038] Steam management system 400 may be an auxiliary steam management system, e.g., an external steam management system. Steam management system 400 may operate during periods of high, variable, or sustained steam production. Steam management system 400 may be activated or deactivated based on one or more system variables (e.g., tank pressure, tank temperature, or device power). Steam management system 400 may provide excess condensing capacity to manage periods of increased heat load and steam production, thereby supplementing the condensing capacity of main condenser 235 when needed.

[0039] Vapor management system 400 may be actively controlled based on conditions measured or determined within apparatus 100. In embodiments, vapor management system 400 may be controlled based on the input of one or more variables, such as pressure, temperature, device power, vapor concentration, or opacity within immersion tank 201. The variables may be measured with electronic sensors, mechanically sensed, estimated based on correlated variables, or determined through any other suitable technique and combinations thereof.

[0040] The vapor management system 400 may include a vapor supply passage 405. The vapor supply passage 405 may fluidly connect the vapor management system 400 to the upper portion 205 of the immersion tank 201. The vapor supply passage 405 may be any suitable type of fluid passage, such as, for example, a tube, a pipe, an integrally formed passage, or a combination thereof.

[0041] 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. Together, the vapor supply channel 405 and the liquid return channel 470 may allow fluid circulation from and to the immersion tank 201. For example, the vapor management system 400 may receive a dielectric vapor 615 from the immersion tank 201 and return a liquid dielectric fluid 620 to the immersion tank 201.

[0042] The steam management system 400 may include a valve 410 in the steam supply flow path 405. The (e.g., flow control) valve 410 may control the flow of steam through the steam supply flow path 405. When open, the valve 410 may allow steam flow from the immersion tank 201 to the steam management system 400 through the steam supply flow path 405. 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 approximately 0.15 psig. In this embodiment, if the pressure in the immersion tank is equal to or greater than 0.15 psig, the valve 410 will open. The valve 410 may remain open until the steam pressure in the immersion tank 201 falls below 0.15 psig, at which point the valve 410 may close. In another embodiment, the threshold pressure setting may be at or between -0.15 psig and 0.15 psig. In another embodiment, the threshold pressure setting may be at or between -0.25 psig and 0.25 psig. In another embodiment, the threshold pressure setting may be at or between -0.9 psig and 0.9 psig. In another embodiment, the threshold pressure setting may be at or between 0 psig and 0.25 psig. In another embodiment, the threshold pressure setting may be at or between -0.25 psig and 0 psig. In another embodiment, the threshold pressure setting may be at or between 1 psig and 5 psig. In another embodiment, the threshold pressure setting may be at or between 4 psig and 10 psig. In another embodiment, the threshold pressure setting may be at or between -1 psig and -5 psig. In another embodiment, the threshold pressure setting may be at or between -4 psig and -10 psig.

[0043] In some embodiments, the threshold pressure setting may be variable instead of fixed. A variable pressure setting may be useful in dealing with anticipated surges in vapor production during transient operation. For example, if device power consumption increases suddenly, there may be a time lag before an increase in vapor pressure is detected through pressure measurements. The increase in vapor production may be accurately predicted by monitoring device power consumption. Upon detecting an increase in device power consumption, the threshold setting may be temporarily lowered to activate the vapor management system 400 sooner than if a fixed threshold setting were used.

[0044] In some applications, the vapor 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 interior volume between an inlet 435 and an outlet 440. The vapor supply passage 405 may be fluidly connected to the inlet 435 of the condensation chamber 430. The vapor supply passage 405 may fluidly connect the outlet of the valve 410 to the inlet 435 of the condensation chamber 430. The vapor supply passage 405 may transport vapor 615 from the immersion tank 201 to the condensation chamber 430 when the valve 410 is open. The condensation chamber 430 may have a volume that is at least 10% of the headspace volume of the immersion tank 201. The condensation chamber 430 may have a volume that is at least 30% of the headspace volume of the immersion tank 201. The condensation chamber 430 may have a volume that is at least 50% of the headspace volume of the immersion tank 201. The condensation chamber 430 may have a volume that is at least 70% as large as 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 lid 225 and enclosed by the sidewalls of the immersion tank 201.

[0045] The condensing chamber 430 may include an auxiliary condenser 451. The auxiliary condenser 451 may be in thermal communication with the condensing chamber 430. The auxiliary condenser 451 may extract heat from the vapor 615 to condense the vapor 615 within the condensing chamber 430. The auxiliary condenser 451 may extend within the interior volume of the condensing chamber 430 or may be in contact with at least one surface of the condensing 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 chiller 446. The liquid chiller 446 may circulate a chilled coolant through the auxiliary condenser 451. In one embodiment, the liquid chiller 446 may circulate a liquid at a temperature of approximately 5-15°C. In another embodiment, the liquid chiller 446 may circulate a liquid at a temperature of approximately -2-10°C. In another embodiment, the liquid chiller 446 may circulate liquid at a temperature of about -10 to -5°C. In another embodiment, the liquid chiller 446 may circulate liquid at a temperature of about -28 to -2°C.

[0046] In one variation, the liquid chiller 446 may be a refrigeration system, as illustrated in Figure 12. The chiller 446 cools a cooling coil to a temperature below ambient temperature (T c ) to maintain the temperature of the fluid in the reservoir 453. The fluid may be a dielectric fluid. The fluid may be the same type of fluid used in the immersion tank 201 to reduce the risk of cross-contamination from leakage or diffusion. Using the same type of fluid may also simplify maintenance operations. The liquid chiller 446 may include a compressor 449, a condenser 447, an expansion valve 450, and an evaporator 448. The liquid chiller 446 may utilize a refrigeration cycle to extract heat from the fluid in the reservoir 453 and reject the heat through the condenser 447.

[0047] The vapor management system 400 may include a variable volume chamber 415 (e.g., a bellows). The variable volume chamber 415 may be made of a vapor-resistant material, such as a metalized polyester film (e.g., Mylar), that has an expandable internal volume. The variable volume chamber 415 may contract when the pressure within the vapor management system 400 is equal to or less than 1 atmosphere. The variable volume chamber 415 may expand when the pressure within the vapor management system 400 is greater than 1 atmosphere. The variable volume chamber 415 may expand the total volume of the vapor management system 400, increasing the total vapor capacity, thereby allowing the system 400 to receive more vapor 615 during transient periods. The expansion of the variable volume chamber 415 may reduce the pressure of the input vapor 615, promoting condensation of the vapor 615.

[0048] Steam management system 400 may include a pressure relief valve 460. Pressure relief valve 460 may be a safety device. Pressure relief valve 460 may open at a predetermined pressure threshold to prevent over-pressurization of steam management system 400. Pressure relief valve 460 may be fluidly connected to condensing chamber 430 via an exhaust flow path 462. In one embodiment, pressure relief valve 460 may be configured to open when the pressure within steam management system 400 is equal to or greater than approximately 0.15 psig. In another embodiment, pressure relief valve 460 may be configured to open when the pressure within steam management system 400 is equal to or greater than approximately 0.20 psig. In yet another embodiment, pressure relief valve 460 may be configured to open when the pressure within steam management system 400 is equal to or greater than approximately 0.25 psig.

[0049] The vapor management system 400 may include a vapor pump 420, as shown in FIG. 13 . The vapor pump 420 may be configured to purge a mixture of air and dielectric vapor 615 from the immersion tank 201 to the condensation chamber 430. The vapor pump 420 may be located upstream of the condensation chamber 430. The vapor pump 420 may have an inlet and an outlet. The inlet of the vapor pump 420 may be fluidly connected to the outlet of the variable volume chamber 415. The outlet of the vapor pump 420 may be fluidly connected to the inlet 435 of the condensation chamber 430. The vapor pump 420 may be capable of reducing the pressure in the immersion tank 201 below atmospheric pressure. The vapor pump 420 overcomes the effects of gravity on fluid flow and allows the vapor management system 400 to be disposed regardless of height or orientation relative to the headspace 206, thereby providing greater design freedom that may be required when implementing the vapor management system 400 in a confined space, such as a vessel 1005 (Figures 1 and 2) or a utility box.

[0050] Vapor pump 420 may be useful for preemptively addressing periods of anticipated high vapor production. In one embodiment, upon detecting an increase in device power consumption that would result in high vapor production, valve 410 may be opened and vapor pump 420 may be activated to purge vapor 615 from headspace 206, thereby reducing the vapor pressure in vessel 201 ahead of the anticipated pressure increase. This approach may reduce the rate of pressure rise in immersion vessel 201 resulting from increased power consumption and vapor production.

[0051] The steam management system 400 may be electronically 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 send a signal to the electronic control unit 480 corresponding to the pressure in the immersion tank 201. The signal may be sent through a wired or wireless connection.

[0052] Electronic control unit 480 can be configured to open or close pressure relief valve 460 based on a signal received from a sensor or other input. Sensor 463 can be a pressure sensor configured to measure the pressure within steam management system 400. Sensor 463 can be configured to send a signal to electronic control unit 480 corresponding to the pressure within steam management system 400. The signal can be sent through a wired or wireless connection.

[0053] The electronic control unit 480 can be configured to activate or deactivate the vapor pump 420 (FIG. 13) based on a signal received from the (e.g., pressure) sensor 412. For example, in the embodiment plotted in FIG. 14, the electronic control unit 480 may activate the vapor pump 420 to purge vapor 615 from the headspace 206 to reduce the bath pressure below atmospheric pressure before initiating the cooling cycle. Reducing the pressure in the immersion bath 201 may lower the boiling temperature of the fluid 620, which may be desirable in certain applications. In the embodiment of FIG. 14, the bath pressure is reduced below atmospheric pressure, and the threshold pressure setting of the valve 410 is set above atmospheric pressure, thereby allowing the operating pressure of the bath 201 to vary over a range that includes values ​​above and below atmospheric pressure. This method may minimize the extent and duration of bath pressure excursions from atmospheric pressure, thereby minimizing fluid loss due to pressure-induced diffusion or leakage. In another embodiment, the vessel pressure may be reduced below atmospheric pressure, and the threshold pressure setting of valve 410 may be set below atmospheric pressure, thereby allowing the operating pressure of vessel 201 to vary in the negative pressure range. This method may be desirable to reduce the boiling temperature of fluid 620.

[0054] In some embodiments, apparatus 100 may include a water separation and filtration system 500 (FIG. 5). As illustrated in FIGS. 5, 10, and 11, water separation and filtration system 500 may include one or more assemblies of the following components: a water separator 565 and—by way of example, rather than limitation—a filtration system 575, which may include a liquid pump 585, a dry filter 590, an impurity filter 580, etc.

[0055] For example, referring 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 the water 715 or other undesired fluid from the dielectric fluid 620. The water separator 565 may capture the water 715 or other undesired fluid and allow the dielectric fluid 620 to pass through. The water 715 or other undesired fluid that accumulates in the water separator 565 may be periodically drained. The amount of accumulated water 715 or other undesired fluid may depend on the ambient humidity, how well the apparatus is sealed, and how frequently the lid 225 of the immersion tank 201 is opened.

[0056] In one embodiment, the water separator 565 may be a gravity-based water separator. The water 715 or other undesired fluid may be less dense than the dielectric liquid 620. Consequently, the captured water 715 or other undesired fluid may settle above the dielectric liquid 620 within the water separator 565. The water 715 or other undesired fluid may be periodically purged from the water separator 565 through a drain valve 573. The dewatered dielectric liquid 620 may occupy a lower portion of the water separator 565. The dewatered dielectric liquid 620 may be withdrawn from the water separator 565 through an outlet 574 located at a lower portion of the water separator 565.

[0057] In an alternative embodiment, the water separator 565 may be a pump-based water separator. As shown in FIG. 23 , the auxiliary condenser 451 may extract heat from the steam 615 and the water vapor 710 to condense the steam 615 and the water vapor 710 in the condensation chamber 430. A liquid pump 576 may be fluidly coupled between the condensation chamber 430 and the water separator 565. The condensate resulting from condensing the steam 615 and the water vapor 710 may then accumulate in the vent chamber, raising the liquid level in the condensation chamber 430. A liquid level sensor 577 operatively disposed in the condensation chamber 430 may be configured to measure the liquid level. If the measured liquid level exceeds a desired liquid level, a control device may be adapted to start the liquid pump 576, resulting in all or a portion of the liquid in the condensation chamber 430 being pumped into the water separator 565. One advantage of this alternative embodiment is that pump 576 means that water separator 565 no longer needs to be located in a position with a significant gravitational potential difference from condensation chamber 430 .

[0058] 11, the water separator 565 may include an inclined perforated plate 566 in a vessel 564. The vessel 564 may be constructed and arranged to include an inlet 571, a dielectric fluid chamber 567, a dielectric fluid drain 569, a water chamber 568, and a water drain 570. In some implementations, the water separator 565 may be configured to separate the dielectric fluid 620 from the water 715 based on liquid properties such as different surface tensions. For example, HFE-7100 has a typical surface tension of 13.6 dynes / cm, while water has a typical surface tension of 72 dynes / cm. As a result, the dielectric fluid and water mixture can flow across the inclined perforated plate 566, but the surface tension difference will cause the dielectric fluid 620, which has a lower surface tension, to flow through the holes or apertures 572 into the fluid chamber 567 below the inclined perforated plate 566, while the water, which has a higher surface tension, will flow to the edge of the inclined perforated plate 566 and into the water chamber 568. While HFE-7100 is used as an example, any type of dielectric fluid with a different dynamic viscosity than water can take advantage of such properties.

[0059] The size of the holes or apertures 572 in the inclined perforated plate 566 may vary based on the surface tension of the dielectric fluid. For example, a mesh size of approximately 60-200 may be effective for separating HFE-7100 from water. A mesh size of 80 means there are 80 holes per square inch of area. A mesh size of 80 may include holes having a diameter of approximately 0.18 mm. In another embodiment, the inclined perforated plate 566 may be replaced with a sieve. The sieve may be made from metal wire. The sieve may have a mesh size of approximately 60-200.

[0060] The apparatus 100 may also include a filtration system 575. In some variations, the filtration system 575 may include a dry filter 590 fluidly connected to the liquid return line 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.

[0061] The apparatus 100 may be constructed from a metal such as carbon steel. The immersion tank 201 may be constructed from metal with welded seams. Metal materials may be preferred over plastic materials because they may effectively prevent moisture migration from the ambient environment to the dielectric fluid 620 in the tank 201. Minimizing moisture migration to the dielectric fluid 620 is desirable to reduce the dehydration demands placed on the water separator 565 and may also reduce the dehydration demands on the desiccant material in the drying filter 590.

[0062] In some applications, the filtration system 575 may include an impurity filter 580. The impurity filter 580 may be fluidly connected to the liquid return line 470 and disposed between the outlet of the drying filter 590 and the inlet of the soaking tank 201. The impurity filter 580 may include activated carbon, charcoal, etc. The impurity filter 580 may capture any impurities or debris.

[0063] In some variations, the apparatus 100 may include a liquid return system. The liquid return system may be configured to return the dielectric liquid 620, condensed from the dielectric vapor, 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 flow path 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.

[0064] 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 subcooled fluid to function properly. Reducing the amount of fluid is desirable to reduce fluid costs, system weight, and system size. Minimizing size and weight can be especially important in mobile and stationary applications where a custom-designed floor is not available to support the device 100.

[0065] In some embodiments, the vapor management system 400 may only be needed periodically. For example, if the electronic device 800 is idle, operating below its maximum power rating, operating at a relatively constant power with little fluctuation, etc., the vapor management system 400 may not be needed until the electronic device power increases. In other embodiments, the vapor management system 400 may be needed frequently but may have sufficient cooling capacity to simultaneously service multiple immersion tanks 201. In either scenario, a central vapor management system 400 may service two or more immersion tanks 201, 201′. FIG. 17 illustrates an embodiment of a two-phase immersion cooling apparatus 1700 having a central vapor management system 400 fluidly connected to the first immersion tank assembly 200 and the second immersion tank assembly 200′. Utilizing a central vapor management system 400 may be less expensive than providing a separate vapor management system 400 for each immersion tank 201, 201′. Utilizing a central vapor management system 400 may conserve floor space in the data center 2000 ( FIG. 4 ). Utilizing a central steam management system 400 may reduce or simplify maintenance. Each dip tank 201, 201′ may be fluidly connected to the steam management system 400 by a corresponding steam supply passage 405, 405′ and may be fluidly connected to the water separation and filtration assembly 500 by a liquid return passage 470.

[0066] The central vapor management system 400 monitors the bath pressure in each immersion tank 201, 201′ (e.g., using (e.g., pressure) sensors 412) and receives dielectric vapor 615 from one tank 201, both tanks 201, 201′, or none of the tanks as needed to maintain the bath pressure within an acceptable range. For example, the central vapor management system 400 may receive vapor from the first immersion tank 201 when the first immersion tank pressure is equal to or greater than a first threshold pressure. The central vapor management system 400 may receive vapor from the second immersion tank 201′ when the second immersion tank pressure is equal to or greater than a second threshold pressure.

[0067] FIG. 18 illustrates a two-phase immersion cooling apparatus 1800 that differs from the apparatus 1700 of FIG. 17 by including vapor pumps 420, 420′ fluidly connected between the corresponding immersion tanks 201, 201′ and the central vapor management system 400. Each vapor pump 420, 420′ may be configured to purge a mixture of air and dielectric vapor from the respective immersion tanks 201, 201′ and pressurize it into the condensation chamber 430. Each vapor pump 420, 420′ may be located upstream of the condensation chamber 430. Each vapor pump 420, 420′ may have an inlet and an outlet. The inlet of each vapor pump 420, 420′ may be fluidly connected to the outlet of the corresponding variable volume chamber 415, 415′. The outlet of each vapor pump 420, 420′ may be fluidly connected to the inlet 435 of the condensation chamber 430. Advantageously, each vapor pump 420 may be capable of reducing the pressure within the respective immersion tank below atmospheric pressure.

[0068] In some embodiments, the vapor management system 400 may be incorporated into the two-phase immersion cooling apparatus 100 and located in a common housing. In other embodiments, the vapor management system 400 may be included in a separate vapor processing unit 900 that fluidly connects to one or more submersion bath assemblies 200, 200′, as illustrated in FIGS. 19-22. The vapor processing unit 900 may be retrofitted to an existing two-phase immersion cooling apparatus 100 to increase vapor management capabilities. For example, if the electronic devices 800 in the data center 2000 are upgraded to consume more power than the electronic devices 800 being replaced, the cooling capacity of the two-phase immersion cooling apparatus 100 may need to be upgraded to manage the additional heat load. Rather than replacing the apparatus 100, the vapor management system 400 may alternatively be added to the apparatus 100 to manage a higher vapor generation rate, allowing the existing submersion bath assemblies 200, 200′ to be reused.

[0069] In some implementations, the vapor processing device 900 may include a housing 905, as shown in FIG. 19 . The vapor processing device 900 may include a vapor management system 400. The vapor management system 400 may include a vapor supply flow path 405 having a vapor supply inlet 401. The vapor management system 400 may include a condensing chamber 430 having an inlet, an outlet, and an auxiliary condenser 451 in thermal communication with the interior volume of the condensing chamber 430. The vapor supply flow path 405 may fluidly connect the vapor supply inlet 401 to an inlet 435 of the condensing chamber 430. The vapor management system 400 may include a flow control valve 410 in the vapor supply flow path 405 between the vapor supply inlet 401 and the inlet 435 of the condensing chamber 430. The vapor management system 400 may include a liquid return flow path 470 fluidly connecting an outlet 440 of the condensing chamber 430 to a liquid return outlet 471. The vapor management system 400 may include a variable volume chamber 415 fluidly connected to the vapor supply passage 405 between the vapor supply inlet 401 and the inlet 435 of the condensing chamber 430. The vapor management system 400 may also include a (e.g., pressure) sensor 412 located in the vapor supply passage 405 and configured to detect the pressure within the immersion tank 201 when fluidly connected thereto. The vapor management system 400 may further include a pressure relief valve 460 fluidly connected to the condensing chamber 430.

[0070] Steam processing device 900 may include water separation and filtration assembly 500. Steam processing device 900 may include water separator 565 and / or filtration system 575, as shown in Figure 10. Filtration system 575 may include one or more of liquid pump 585, dry filter 590, impurity filter 580, etc.

[0071] FIG. 19 illustrates a steam processing device 900 having a single steam supply inlet 401. FIG. 20 illustrates a steam processing device 900 having two steam supply inlets 401, 401′. In other embodiments, the steam processing device 900 may have more than two steam supply inlets 401, 401′ such that the device 900 receives steam from three or more immersion tanks 201, 201′. In some embodiments, the steam processing device 900 may receive steam from a group of immersion tanks. For example, the steam processing device 900 may receive steam from a group of immersion tanks 201, 201′ provided in a multiple tank assembly 200, 200′, as illustrated in FIG. 2 or FIG. 4. Having a central steam processing device 900 may be more efficient and cost-effective than having a steam processing device 900 for each immersion tank 200.

[0072] In some variations, the vapor treatment device 900 may include a vapor pump 420 to enable the device 900 to actively purge the dielectric vapor 615 and air 705 (FIG. 5) from the headspace 206 (FIG. 5) of the immersion tank 200. FIG. 21 illustrates a vapor treatment device 900 with a single vapor supply inlet 401 and a single vapor pump 420 fluidly connected to the vapor management system 400. FIG. 22 illustrates a vapor treatment device 900 with two vapor supply inlets 401, 401′ and corresponding vapor pumps 420, 420′ fluidly connected to corresponding vapor supply passages 405, 405′ of the vapor management system 400.

[0073] How it works Prior to use, the immersion tank 201 may be partially filled with a liquid dielectric fluid 620, as illustrated in FIG. 5. The remainder of the immersion tank 201 may be filled with air 705 at approximately atmospheric pressure (e.g., 1 atmosphere). The interface between the liquid dielectric fluid 620 and the air 705 may define the liquid line 605. In some implementations, the fluid 620 may be non-toxic. Furthermore, in some variations, the fluid 620 may be non-conductive and pose no danger to the electronic device.

[0074] An electronic device 800 requiring cooling, such as a server, switch, router, firewall, etc., may be submerged in the fluid 620 within the immersion bath 201, as shown in FIG. 5 . For example, the electronic device 800 may be fully submerged and disposed below the liquid line 605. Power and communication cables (not shown) may extend from the electronic device 800 to a connection location outside the immersion bath 201. The cables may pass through openings in the lid 225 or bath wall. In another embodiment, the immersion bath 201 may include integrated connectors within the bath 201 to simplify cable management. In some applications, the electronic device 800 may be placed in a storage rack within the immersion bath 201.

[0075] The dielectric fluid 620 in the immersion tank 201 may initially be at approximately room temperature. After the electronic device 800 is immersed in the fluid and powered, the device 800 may begin to generate waste heat as a by-product of power consumption. The heat may be absorbed by the dielectric fluid 620. If the heat flux from the device 800 is high enough, localized boiling of the dielectric fluid 620 may occur. The boiling may generate vapor bubbles that rise into the liquid line 605 through buoyancy and enter the headspace 206 of the immersion tank 201. Because the dielectric vapor 615 may be denser than air 705, a saturated vapor region 625 may eventually form above the liquid line 605, as illustrated in FIG. 5 . The layer of vapor may be referred to as a vapor blanket 625. If the vapor generation rate exceeds the condensation rate, the depth of the vapor blanket 625 will increase. Eventually, the vapor level will approach the main condenser 235. Heat transfer from the vapor 615 to the main condenser 235 may facilitate condensation of the vapor 615 into liquid 620. The condensed liquid 620 will then passively return to the liquid bath.

[0076] When electronic device 800 is operating at steady state, the rate of vapor production and the rate of condensation by main condenser 235 may reach equilibrium, leading to a relatively constant vapor pressure within immersion tank 201. The vapor pressure for HFE-7100 can be calculated using the Antoine equation shown below, where P is the vapor pressure and T is the temperature in degrees Celsius: lnP vapor=22.415-3641.9(1 / (T+273))

[0077] As power consumption by the electronic device 800 increases, waste heat and steam production will also increase. If high power consumption persists, at some point the rate of steam production may overwhelm the condensing capacity of the main condenser 235. Steam pressure within the immersion tank 201 will then begin to rise. When the pressure within the immersion tank 201 reaches a predetermined threshold, the valve 410 may open, as illustrated in FIG. 6, and steam 615 will escape from the immersion tank 201 into the steam management system 400. As the steam management system 400 receives the dielectric fluid vapor 615, air 705, and water vapor 710 from the headspace 206 of the immersion tank 201, the variable volume chamber 415 will expand, as illustrated in FIG. 7.

[0078] FIG. 8 shows a plot of immersion tank 201 pressure and device 800 power consumption versus time. In this embodiment, electronic device 800 is idle or operates at low power for a period of time. During that time, vapor production may be managed entirely by main condenser 235, and vapor management system 400 may remain in standby mode. Eventually, device power consumption may increase. The increased power consumption may generate more waste heat, which may in turn generate more dielectric vapor 615. As vapor production increases, the condensing capacity of main condenser 235 may eventually be exceeded. As vapor 615, air 705, and water vapor 710 accumulate in headspace 206, immersion tank 201 pressure begins to rise until it reaches a predetermined threshold pressure setting. Upon reaching a predetermined threshold pressure setting, the flow control valve 410 may be actuated (e.g., by a signal from the (e.g., pressure) sensor 412), thereby allowing the steam 615, air 705, and water vapor 710 to escape from the immersion tank 201 and enter the steam management system 400, as illustrated in FIG. 6 . Actuation of the flow control valve 410 may cause the steam management system 400 to switch from standby mode to active mode and turn on the chiller 446 or lower its setpoint temperature to a level appropriate for condensing the incoming steam 615 and water vapor 710. As the steam 615, air 705, and water vapor 710 exit the immersion tank 201, the tank pressure may decrease. Eventually, the tank pressure may fall below the threshold pressure setting of the flow control valve 410, causing the flow control valve 410 to close, trapping the steam 615, air 705, and water vapor 710 received from the immersion tank 201 in the steam management system 400, as illustrated in FIG. 5 . The steam 615 and water vapor 710 may then be condensed in the condensation chamber 430, optionally dewatered in the water separator 565, and further dried and filtered through a drying filter 590 and an impurity filter 580, respectively, before being returned to the immersion tank 201 as the dielectric liquid 620. The vapor management system 400 may be cycled on and off as needed to receive and condense the steam 615 and water vapor 710 from the immersion tank 201, thereby maintaining the pressure within the immersion tank 201 at or below the desired operating pressure.

[0079] In one embodiment, it may be desirable to anticipate an increase in steam production that would require operation of the steam management system 400. The increase in steam production may be anticipated by monitoring device power consumption. When device power consumption exceeds a predetermined level, or alternatively, exceeds a predetermined level for a predetermined period of time, the steam management system 400 may switch from standby mode to active mode. Switching from standby mode to active mode may involve operating the chiller 446 or lowering the setpoint temperature of the chiller 446 to a level appropriate for condensing the admitted steam 615 and water vapor 710. This advance operation may allow sufficient time for the chiller 446 ( FIG. 6 ) to reach the desired operating temperature before the valve 410 is opened to admit the steam 615, air 705, and water vapor 710 from the immersion tank 201. This approach allows for energy savings when the steam management system 400 is in standby mode, as chiller temperature and chiller power consumption can be reduced.

[0080] In some cases, unexpected heat loads may exist within the immersion bath 201 and must be safely mitigated. For example, an unexpected heat load may occur if the electronic device 800 malfunctions and exceeds its maximum power consumption rating. When this occurs, the amount of heat generated, as well as the steam 615 and water vapor 710, may exceed the condensation capacity of the vapor management system 400. In practice, the flow control valve 410 will open when the bath pressure reaches a predetermined threshold setting for the flow control valve 410 ( FIG. 6 ). As the steam 615, air 705, and water vapor 710 fill the vapor management system 400, the bellows 415 may be configured to expand to accommodate the additional steam 615, air 705, and water vapor 710, as illustrated in FIG. 7 . If steam production continues to increase after the bellows 415 is fully expanded, the pressure within the vapor management system 400 (e.g., as measured by the (pressure) sensor 463) will continue to rise. To avoid mechanical failure due to overpressure, pressure relief valve 460 may be configured to activate when the pressure within steam management system 400 exceeds the maximum allowable pressure, as shown in Figure 9. Steam 615, air 705, and water vapor 710 will then be vented to the ambient environment, thereby reducing the pressure within steam management system 400 and immersion tank 201 and mitigating the risk of mechanical failure. Venting steam 615, air 705, and water vapor 710 to the ambient environment results in fluid loss, which is undesirable, but fluid loss is preferable to the safety risks associated with overpressure.

[0081] As used herein, the term "fluid" may refer to a substance in a gaseous state, a liquid state, or a two-phase mixture of gas and liquid. A fluid may be capable of undergoing a phase change from liquid to vapor or vice versa. A liquid may form a free surface not created by the container in which it resides, while a gas may not.

[0082] As used herein, the term "vapor" may refer to a substance in the gas phase at a temperature below the substance's critical temperature. Thus, a vapor may be condensed to a liquid by increasing the pressure without decreasing the temperature.

[0083] As used herein, the term "two-phase mixture" may refer to a vapor phase of a substance coexisting with a liquid phase of the substance. When this occurs, the partial pressure of the gas may equal the vapor pressure of the liquid.

[0084] The dielectric fluid 620 may be selected for use in an immersion cooling device based on a variety of factors, including operating pressure, temperature, boiling point, cost, or safety regulations governing installation (e.g., regulations set forth in ASHRAE Standard 15 regarding the amount of fluid allowed per volume of occupied building space).

[0085] In some cases, fluid selection may be influenced by desired dielectric properties, desired boiling point, or compatibility with the materials used to fabricate 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 to the system components and no adverse effects on the device 800 components.

[0086] A dielectric fluid 620, such as a hydrofluorocarbon (HFC) or hydrofluoroether (HFE), can be used as the fluid within the immersion cooling device 100. Unlike water, the dielectric fluid can be used in direct contact with electronic devices 800, such as microprocessors 801, memory modules, power inverters, etc., without the risk of shorting electrical connections.

[0087] Non-limiting examples of dielectric fluids include 1,1,1,3,3-pentafluoropropane (known as R-245fa), hydrofluoroethers (HFEs), 1-methoxyheptafluoropropane (known as HFE-7000), and methoxy-nonafluorobutane (known as HFE-7100). Hydrofluoroethers, including HFE-7000, HFE-7100, HFE-7200, HFE-7300, HFE-7500, and HFE-7600, are commercially available as NOVEC Engineered Fluids from 3M Company, headquartered in Mapleton, Minnesota. FC-40, FC-43, FC-72, FC-84, FC-770, FC-3283, and FC-3284 are also commercially available as FLUOROINERT Electronic Liquids from 3M Company.

[0088] NOVEC 7100 has a boiling point of 61°C, a molecular weight of 250g / mol, a critical temperature of 195°C, a critical pressure of 2.23MPa, a vapor pressure of 27kPa, a heat of vaporization of 112kJ / kg, and a viscosity of 1510kg / m 3 NOVEC 7100 has a liquid density of 1.0 MPa, a specific heat of 1183 J / kg-K, a thermal conductivity of 0.069 W / mK, and a dielectric strength of approximately 40 kV for a 0.1 inch gap. NOVEC 7100 works well for certain electronic devices 800, such as power electronic devices 800 that generate high heat loads and can safely operate at temperatures above approximately 80° C.

[0089] NOVEC 7100 can be used to cool a microprocessor 801 that has a preferred operating core temperature of approximately 60-70° C. If the microprocessor 801 is idle and has a surface temperature below 61° C., subcooled NOVEC 7100 near the microprocessor 801 may not experience localized boiling. If the microprocessor 801 is fully utilized and has a surface temperature above 61° C., the NOVEC 7100 may experience vigorous localized boiling and steam generation near the microprocessor.

[0090] NOVEC 649 Engineered Fluid is available from 3M Company. It is a fluoroketone fluid (C6-fluoroketone) with a low global warming potential (GWP). It has a boiling point of 49°C, a thermal conductivity of 0.059, a molecular weight of 316 g / mol, a critical temperature of 169°C, a critical pressure of 1.88 MPa, a vapor pressure of 40 kPa, a heat of vaporization of 88 kJ / kg, and a viscosity of 1600 kg / m 3 has a liquid density of

[0091] NOVEC 649 may be used to cool a microprocessor 801 that has a preferred operating core temperature of approximately 60-70° C. If the microprocessor 801 is idle and has a surface temperature below 49° C., the subcooled NOVEC 649 near the microprocessor 801 may not experience localized boiling. If the microprocessor 801 is fully utilized and has a surface temperature above 49° C., the NOVEC 649 may experience vigorous localized boiling and steam generation near the microprocessor 801.

[0092] The elements and method steps described herein can be used in any combination, whether stated or not. All combinations of method steps described herein can be performed in any order unless otherwise indicated or made clear by the context in which the referenced combination is made.

[0093] As used herein, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise.

[0094] As used herein, the unit "psig" refers to gauge pressure in pounds per square inch. Positive values ​​indicate pressures above atmospheric pressure. Negative values ​​indicate pressures below atmospheric pressure.

[0095] As used herein, the term "fluidly connected" can describe a first component that is directly connected to a second component, or a first component that is indirectly connected to the second component via one or more intervening components, where a fluid, whether gaseous, liquid, or two-phase mixture, can pass from the first component to the second component without escaping to the atmosphere.

[0096] Numerical ranges used herein are intended to include all numbers and subsets of numbers within that range, whether specifically disclosed or not. Furthermore, these numerical ranges should be construed as providing support for any claim directed to any number or subset of numbers within that range. For example, a disclosure of 1 to 10 should be construed as supporting ranges of 2 to 8, 3 to 7, 5 to 6, 1 to 9, 3.6 to 4.6, 3.5 to 9.9, etc.

[0097] In addition to the structural elements and process step limitations described herein, the methods and compositions of the present invention can comprise, consist of, or consist essentially of any additional or optional steps, components, or limitations described herein or otherwise useful in the art.

[0098] It is understood that this invention is not limited to the particular construction and arrangement of parts illustrated and described herein, but encompasses modifications thereof that fall within the scope of the claims.

[0099] 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 may be possible in light of the above teachings. The embodiments were chosen and described to explain the principles of the invention and its practical application, so as to enable those skilled in the art to best utilize the invention in various embodiments and variations suited to the particular uses contemplated. It is intended that the claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art. [Explanation of symbols]

[0100] 100 Two-phase immersion cooling system 200 Immersion Tank Assembly 200' Dip Tank Assembly 201 Immersion tank, sealed tank 201' Soaking tank 205 Upper 206 Headspace 210 Lower 215 Internal volume 220 aperture 225 Lid 230 Electrical insulating layer 235 Main condenser 240 Heat Rejection System 245 Coolant Pump 250 Freeboard Condenser 400 Steam Management System, Central Steam Management System 401 Steam supply inlet 401' Steam supply inlet 405 Steam supply channel 405' Steam supply channel 410 Flow control valve 412 Sensors 415 Variable volume chamber, bellows 415' variable volume chamber 420 Steam Pump 420' Steam Pump 430 Condensation chamber 435 Entrance 440 Exit, entrance 446 Liquid Chiller 447 Condenser 448 Evaporator 449 Compressor 450 Expansion Valve 451 Auxiliary condenser, cooling coil 452 Pump 453 Reservoir 460 Pressure Relief Valve 462 Discharge flow path 463 Sensors 470 Liquid return channel 471 Liquid return outlet 480 Electronic Control Unit 500 Water Separation and Filtration System, Filtration Assembly 564 Container 565 Water separator 566 Inclined perforated plate 567 Dielectric fluid chamber 568 Water room 569 Dielectric Fluid Drain 570 Water Drain 571 Entrance 572 Holes or holes 573 Drain valve 574 Exit 575 Filtration System 576 Liquid Pump 577 Liquid level sensor 580 Impurity Filter 585 Liquid Pump 590 Dry Filter 605 Liquid Line 615 Steam 620 Dielectric fluids, dielectric liquids 625 Steam Blanket 705 Air 710 Water Vapor 715 water 800 Electronic Devices 801 microprocessor 900 Steam treatment equipment, central steam treatment equipment 905 Case 1000 Modular Data Center 1005 Containers, shipping containers 1500 Two Phase Immersion Cooler 1600 Two Phase Immersion Cooler 1605 area 1610 area 1700 Two Phase Immersion Cooler 1800 Two Phase Immersion Cooler 2000 Previous Data Center

Claims

1. 1. A dip tank assembly comprising: at least one immersion tank, each forming an internal volume; The top and The bottom and an immersion tank assembly comprising an immersion tank comprising a main condenser in thermal communication with the interior volume of the immersion tank; a vapor management system fluidly connected to the dip tank assembly, comprising: a condensation chamber, forming an internal volume; The entrance and The exit and a condensing chamber including an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a steam supply channel fluidly connecting the upper portion of the immersion tank to the inlet of the condensing chamber; a valve in the vapor supply flow path between the top of the immersion tank and the inlet of the condensing chamber, the valve being open when the measured pressure at the immersion tank assembly is greater than a predetermined threshold setting and being closed when the measured pressure at the immersion tank assembly is less than the predetermined threshold setting; a liquid return flow path fluidly connecting the outlet of the condensing chamber to the dip tank assembly; A two-phase immersion cooling apparatus comprising:

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

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

4. 4. The two-phase immersion cooling apparatus of claim 1, further comprising a sensor for detecting a 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. an exhaust flow channel fluidly connected to the condensation chamber; a pressure relief valve fluidly connected to the exhaust flow path; a sensor located in the steam management system that detects pressure within the steam management system; 5. The two-phase immersion cooling apparatus of claim 1, further comprising:

6. 6. The two-phase immersion cooling apparatus of claim 1, further comprising a water separator fluidly connected to the liquid return flow path between the outlet of the condensing chamber and the inlet to the immersion tank assembly.

7. 7. The two-phase immersion cooling apparatus of claim 1, further comprising a liquid pump fluidly connected to the liquid return flow path and disposed between the outlet of the condensing chamber and the inlet to the immersion tank assembly.

8. 8. The two-phase immersion cooling apparatus of claim 1, further comprising a dry filter fluidly connected to the liquid return flow path and disposed between the outlet of the condensing chamber and the inlet to the immersion tank assembly.

9. 9. The two-phase immersion cooling apparatus of claim 1, further comprising an impurity filter fluidly connected to the liquid return flow path and disposed between the outlet of the condensing chamber and the inlet to the immersion tank assembly.

10. 10. The two-phase immersion cooling apparatus of claim 1, further comprising 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.

11. 1. A dip tank assembly comprising: at least one immersion tank, each forming an internal volume; The top and The bottom and an immersion tank assembly comprising an immersion tank having a main condenser in thermal communication with the interior volume; a vapor management system fluidly connected to the dip tank assembly, comprising: a condensation chamber, forming an internal volume; The entrance and The exit and a condensing chamber including an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a steam supply channel fluidly connecting the upper portion of the immersion tank to the inlet of the condensing chamber; a valve provided in the steam supply channel between the upper portion of the immersion tank and the inlet of the condensing chamber; a liquid return flow path fluidly connecting the outlet of the condensing chamber to an inlet to the immersion tank assembly; a sensor configured to detect pressure in the immersion tank assembly and to generate and transmit a signal based on the measured pressure; an electronic control unit configured to receive the signal from the sensor and to send a command signal to the valve; A two-phase immersion cooling apparatus comprising:

12. 12. The two-phase immersion cooling apparatus of claim 11, wherein the sensor is provided in at least one of the immersion tank assembly or the steam supply flow path between the valve and the immersion tank assembly.

13. 13. The two-phase immersion cooling apparatus of claim 11 or 12, wherein the condensation chamber has a volume at least 10% as large as the headspace volume of the immersion tank.

14. 14. The two-phase immersion cooling apparatus of claim 11, wherein the condensing chamber further comprises a chiller fluidly connected to the auxiliary condenser.

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

16. A method of immersion cooling a heat-generating device performed by a two-phase immersion cooling apparatus, comprising: The two-phase immersion cooling device comprises: a dip tank assembly; at least one immersion tank, each forming an internal volume; The top and The bottom and an immersion tank assembly comprising an immersion tank comprising a main condenser in thermal communication with the interior volume of the immersion tank; a vapor management system fluidly connected to the dip tank assembly; a condensation chamber, forming an internal volume; The entrance and The exit and a condensing chamber including an auxiliary condenser in thermal communication with the interior volume of the condensing chamber; a steam supply channel fluidly connecting the upper portion of the immersion tank to the inlet of the condensing chamber; a valve provided in the steam supply channel between the upper portion of the immersion tank and the inlet of the condensing chamber; a vapor management system including a liquid return flow path fluidly connecting the outlet of the condensing chamber to the dip tank assembly; Equipped with The method comprises: detecting a pressure in the immersion tank; opening the valve when the measured pressure at the immersion tank assembly is greater than a predetermined threshold setting, thereby allowing dielectric vapor and other gases from the immersion tank assembly to enter the condensing chamber; closing the valve when the measured pressure at the immersion tank assembly is less than the predetermined threshold setting; and at least one of condensing the dielectric vapor and other gases to a liquid state in the condensation chamber; returning condensed dielectric liquid to the immersion tank assembly through the liquid return channel; A method comprising:

17. The method of claim 16 further comprising circulating a coolant through the main condenser, the coolant having a temperature above ambient temperature.

18. circulating a first coolant through the main condenser; circulating a second coolant through the auxiliary condenser; the temperature of the first coolant is greater than the temperature of the second coolant; 18. The method of claim 16 or 17.

19. providing a vapor pump fluidly connected to the vapor supply line and disposed between the submerged tank assembly and the inlet of the condensing chamber; operating the vapor pump while the valve is open to purge gas from the headspace of the immersion tank and reduce the pressure within the immersion tank below atmospheric pressure; 19. The method of any one of claims 16 to 18, further comprising:

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

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