Vapor Management System and Method in Immersion Cooling

Abstract

A thermal management system for a computing device includes an immersion chamber, a cooling fluid, a plurality of heat-generating components, and a means for removing vapor from a cooling zone of the cooling fluid. The cooling fluid is contained within the immersion chamber and fills at least a portion of the immersion chamber. The plurality of heat-generating components are disposed within the cooling fluid and arranged in a continuum. The continuum defines a cooling zone of the cooling fluid in contact with the plurality of heat-generating components for cooling the plurality of heat-generating components.

Description

Background Art

[0001]

[0001] Computing devices can generate a large amount of heat during use. Computing components are likely to be damaged by heat and generally require a cooling system to keep the temperature of the components within a safe range while the processing or usage load is high. Since liquid cooling fluids have a greater heat mass than air or gas cooling, liquid cooling can effectively cool components. By generating a vaporized fluid from the liquid cooling fluid, the liquid cooling fluid can be maintained at a lower temperature. Vapor within the cooling fluid can potentially have an adverse effect on the cooling performance of the cooling fluid.

Summary of the Invention

[0002]

[0002] In one embodiment, a heat management system for a computing device includes an immersion chamber, a cooling fluid, a plurality of heat - generating components, and means for removing vapor from a cooling volume of the cooling fluid. The cooling fluid is housed within the immersion chamber and fills at least a portion of the immersion chamber. The plurality of heat - generating components are disposed within the cooling fluid and are arranged in a continuum. This continuum defines a cooling volume where the cooling fluid contacts the plurality of heat - generating components to cool the plurality of heat - generating components.

[0003]

[0003] This abstract is provided to introduce in a simplified form a selection of concepts that are further described below in the detailed description. This abstract is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0004]

[0004] Further other features and advantages are specified in the following description, are partly self-evident from this description, or can be acquired by practicing the teachings herein. The features and advantages of the present disclosure can be realized and obtained by the components (instruments) and combinations specifically pointed out in the appended claims. The features of the present disclosure will become even more fully apparent from the following description and the appended claims, or can be acquired by practicing the present disclosure specified below.

Brief Description of the Drawings

[0005]

[0005] To describe the embodiments in which the features and other features of the present disclosure described above can be obtained, a more specific description will be made with reference to the specific embodiments shown in the accompanying drawings. For better understanding, throughout the various accompanying drawings, the same reference numerals are assigned to the same elements. Although some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings can also be drawn at the same scale. Understanding that the drawings show only some examples of the embodiments, the use of the accompanying drawings will describe and explain the embodiments more specifically and in detail.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0006]

[0013] The present disclosure generally relates to thermal management systems and methods for electronic devices or other heat generating components. An immersion chamber surrounds the heat generating component in a liquid cooling fluid, and the liquid cooling fluid removes heat from the heat generating component to cool the heat generating component. As the cooling fluid absorbs heat from the heat generating component, the temperature of the cooling fluid rises, the cooling fluid vaporizes, and the vapor is mixed into the liquid of the cooling fluid.

[0007]

[0014] In certain embodiments, thermal management of the heat generating component includes removing or managing vapor in the cooling zone of the cooling fluid proximate to the heat generating component. As the amount of vapor increases in the cooling zone, the thermal conductivity and thermal mass of the cooling fluid in the cooling zone decrease. The resulting effect is known as dryout. As a result of dryout, the thermal management capacity of the cooling zone decreases, and the temperature of the heat generating component may increase in an undesirable and / or uncontrollable manner.

[0008]

[0015] In certain embodiments, dryout can be suppressed and / or prevented by one or more uses of the systems and / or methods described herein. Vaporization of the cooling fluid requires thermal energy to overcome the latent heat of vaporization, and in addition to convective cooling by the liquid cooling fluid, a certain amount of vaporization enables removal of thermal energy. By enabling vaporization that does not allow a dryout condition, thermal management can be improved.

[0009]

[0016] Referring now to FIG. 1, immersion cooling system 100 according to the present disclosure includes a chamber 102, within which a cooling fluid 104 is contained. A capacitor 106 is disposed above the liquid cooling fluid 108, in the upper portion of the cooling fluid 104, and within the vapor 110 of the cooling fluid 104. The capacitor 106 cools a portion of the vapor 110 of the cooling fluid 104 back to the liquid phase, removes thermal energy from the system, and reintroduces the cooling fluid 104 into the immersion bath 112 of the liquid cooling fluid 108.

[0010]

[0017] In certain embodiments, the immersion bath 112 of the liquid cooling fluid 108 has a plurality of heat generating components 114 disposed within the liquid cooling fluid 108. The liquid cooling fluid 108 surrounds the heat generating components 114 and can also surround other objects or portions attached to the heat generating components 114. In certain embodiments, the heat generating components 114 are disposed on one or more supports 116 within the liquid cooling fluid 108. The supports 116 support one or more heat generating components 114 within the liquid cooling fluid 108 and can move the cooling fluid 104 around the periphery of the heat generating components 114. In certain embodiments, the supports 116 are thermally conductive in order to conduct heat away from the heat generating components 114. The support(s) 116 can increase the effective surface area from which the cooling fluid 104 can remove heat by convective cooling. One or more of the heat generating components 114 include, in certain embodiments, a heat sink, or other device that scavenges thermal energy and effectively increases the surface area of the heat generating components 114.

[0011]

[0018] As described above, the conversion of the liquid cooling fluid to its vapor phase requires an input of thermal energy to overcome the latent heat of vaporization, which can increase the heat capacity of the cooling fluid and provide an effective mechanism for removing heat from the heat-generating components. As shown in FIG. 2, the formation of vapor bubbles 118 in the liquid cooling fluid 108 is not uniform in a conventional immersion cooling system 100. In a conventional system having vertically aligned heat-generating components 114, equal heat generation by the heat-generating components 114 produces vaporization of the cooling liquid 104 along the vertical stack of the heat-generating components 114. Since the vapor bubbles 18 rise within the liquid cooling fluid 108, a higher vapor-to-liquid ratio occurs in the region of the cooling fluid 104 directly surrounding the heat-generating components 114 that are located higher in the vertical stack. This is because the liquid cooling fluid 108 vaporizes near the heat-generating components 114 and the vapor bubbles 118 rise from a lower position within the liquid cooling fluid.

[0012]

[0019] In certain embodiments according to the present disclosure, a thermal management system for a computing device includes one or more mechanisms for removing vapor from a cooling zone of a cooling fluid that directly surrounds a heat-generating component. The cooling zone is the region of the cooling fluid that directly surrounds the heat-generating component and is responsible for convective cooling of the heat-generating component (including both the liquid and vapor phases). In certain embodiments, the cooling zone is the region of the cooling fluid that is within 5 millimeters (mm) of the heat-generating component. In certain embodiments, the cooling zone is the region of the cooling fluid that is within 5 mm of a vertical stack (support and heat-generating components). In certain embodiments, the cooling zone is defined by a vertical cylinder that surrounds each of the vertical stacks, and no part of this cylinder enters within 5 mm of the heat-generating component.

[0013]

[0020] The immersion cooling system described herein includes one or more mechanisms that remove vapor from the cooling zone and maintain the vapor-to-liquid ratio below a target value even when the heat-generating component is operating at maximum load. In certain embodiments, when the heat-generating component is operating at maximum load, less than 50% vapor remains in the cooling zone. In certain embodiments, when the heat-generating component is operating at maximum load, less than 25% vapor remains in the cooling zone. In certain embodiments, when the heat-generating component is operating at maximum load, less than 15% vapor remains in the cooling zone. In certain embodiments, when the heat-generating component is operating at maximum load, less than 10% vapor remains in the cooling zone. In certain embodiments, when the heat-generating component is operating at maximum load, less than 5% vapor remains in the cooling zone.

[0014]

[0021] The cooling fluid has a boiling point lower than the critical temperature at which thermal damage occurs to the heat-generating component. For example, the heat-generating component may be a computing device that is damaged at temperatures higher than 100 degrees Celsius (°C). In certain embodiments, the boiling point of the cooling fluid is less than the critical temperature of the heat-generating component. In certain embodiments, the boiling point of the cooling fluid is less than about 90 °C. In certain embodiments, the boiling point of the cooling fluid is less than about 80 °C. In certain embodiments, the boiling point of the cooling fluid is less than about 70 °C. The cooling fluid includes water in certain embodiments. The cooling fluid includes glycol in certain embodiments. The cooling fluid includes a combination of water and glycol in certain embodiments. The cooling fluid is an aqueous solution in certain embodiments. The cooling liquid is an electronic liquid such as FC-72 available from 3M or a similar non-conductive fluid in certain embodiments. In certain embodiments, the heat-generating component, the support, or other elements of the immersion cooling system located within the cooling fluid have nucleation sites on their surfaces that promote nucleation of vapor bubbles of the cooling fluid at temperatures below the boiling point of the cooling fluid.

[0015]

[0022] In one embodiment, the immersion cooling system includes one or more mechanisms to displace vapor from the cooling region to reduce and / or maintain the vapor-to-liquid ratio. In the immersion tank, an angled vapor diffuser may be disposed above one or more of the heat-generating components. The vapor diffuser is angled with respect to the direction of the vapor flow (i.e., vertically upward) such that vapor bubbles generated by the heat-generating component encounter the angled vapor diffuser and are laterally biased as the vapor bubbles rise through the liquid due to the relative buoyancy of the vapor.

[0016]

[0023] In one embodiment, at least one vapor diffuser is flush with a surface oriented at a fixed angle with respect to the direction of the vapor flow, and the vapor flow crosses this surface. In one embodiment, the at least one vapor diffuser has a plurality of surfaces (or curved surfaces), with a portion of the vapor diffuser oriented at a first angle and a portion of the vapor diffuser oriented at a different second angle to direct vapor bubbles in different lateral directions. In one example, the vapor diffuser is V-shaped, with a portion of the vapor generated by the heat-generating component being directed in a first lateral direction and another portion of the vapor being directed in a second lateral direction. In one embodiment, the vapor diffuser directs all of the vapor generated by the associated heat-generating component in a first direction. In one embodiment, the vapor diffuser directs approximately half of the vapor in a first direction and half of this vapor in a second direction.

[0017]

[0024] In one embodiment, a combination of the outer shapes of the vapor diffusers can be used to move the vapor bubbles away from the vertical stack or continuum of the heat generating components and disperse them throughout the immersion chamber. For example, at least one of the vapor diffusers may be oriented at a first angle with respect to the direction of the vapor flow, and a second vapor diffuser may be oriented at a second angle with respect to the direction of the vapor flow. In one example, the immersion cooling system includes at least one vapor diffuser having one plane and a second vapor diffuser having a plurality of planes and / or curved surfaces.

[0018]

[0025] Referring now to FIG. 3, an embodiment of an immersion cooling system 200 is shown, where a vapor diffuser 220 is disposed within a liquid cooling fluid 208 above and / or between at least a portion of the heat generating components 214. The heat generating components 214 raise the temperature of the liquid cooling fluid 208 adjacent to the heat generating components 214 until the liquid cooling fluid 208 vaporizes into vapor bubbles 218. The vapor bubbles 218 rise within the liquid cooling fluid 208 until they strike the vapor diffuser, which deflects the vapor bubbles 218 laterally and away from the heat generating components 214 (e.g., in the direction of the vapor flow).

[0019]

[0026] The steam diffuser can further vary the spatial orientation within the immersion chamber in three dimensions. For example, in a continuum of heat-generating components, the first heat-generating component may have a first steam diffuser disposed above the first heat-generating component, and the second heat-generating component disposed above the first heat-generating component in the continuum may have a second steam diffuser disposed above the second heat-generating component. The first steam diffuser and the second steam diffuser can be oriented at the same angle (e.g., 30°) with respect to the direction of the steam flow, but can also be oriented in different lateral directions such that the first steam diffuser directs steam bubbles to the right side of the continuum of heat-generating components and the second steam diffuser directs steam bubbles to the left side of the continuum of heat-generating components. In one example, yet another steam diffuser in the continuum can also direct steam bubbles forward and / or backward (perpendicular to the first steam diffuser and the second steam diffuser).

[0020]

[0027] In one embodiment, the vapor diffuser has different textures on the bottom surface and the top surface. For example, the bottom surface can be made smooth, or smoother than the top surface, to allow vapor bubbles to flow along the bottom surface without being hindered. The top surface may have a texture with greater undulations than the bottom surface, such as nucleation sites, or a rougher, wavy, or irregular texture than the bottom surface. The textured top surface can prevent rising bubbles from floating up and adhering to the top surface around the edge of the vapor diffuser when the bubbles float. Further, the textured top surface can encourage any bubbles formed on this top surface to be more easily released from the top surface and not remain trapped on the surface of the top surface. In one embodiment, the edge of the vapor diffuser includes one or more release features to encourage bubbles to be discharged upward in the direction of the vapor flow, adhere to the edge, and otherwise not remain on the edge and impede the flow. For example, the release feature may include an irregular or non-linear edge that suppresses the formation of vortices, allowing bubbles not to be captured in the vortices in the edge flow and to be swept towards the top surface of the vapor diffuser.

[0021]

[0028] The vapor diffuser can cause the immersion chamber to change the vapor flow path from the upward direction of the vapor flow. By inducing the vapor path to move away from the cooling region, the immersion cooling system can control the vapor-to-liquid ratio in the cooling region and enhance the cooling efficiency. The thermal control device can locally adjust the fluid temperature to control the vapor-to-liquid ratio in the cooling region and enhance the cooling efficiency.

[0022]

[0029] In one embodiment, a micro - capacitor is disposed within an immersion tank of a liquid - cooling fluid. The micro - capacitor can lower the temperature of the cooling fluid below the vaporization temperature in order to condense the vapor within the immersion tank and return it to the liquid phase. In one embodiment, the micro - capacitor is a solid - state cooler, such as a Peltier cooler. In one embodiment, the micro - capacitor includes conduits for passing a secondary cooling fluid (e.g., refrigerant) through the micro - capacitor, and the secondary cooling fluid is at a lower temperature than the cooling fluid of the immersion tank. In one embodiment, the micro - capacitor is at least 2 millimeters from the surface of the heat - generating component.

[0023]

[0030] FIG. 4 shows another embodiment of the immersion cooling system 300, where a vapor diffuser 320 is disposed adjacent to the heat - generating component 314 on the outer laminate, and a micro - capacitor 322 is disposed adjacent to the heat - generating component 314 on the inner laminate. In one embodiment, the vapor bubbles 318 generated by the heat - generating component 314 on the outer laminate are directed towards the micro - capacitor 322, and the micro - capacitor 322 lowers the temperature of the liquid - cooling fluid 308 and the vapor bubbles 322 to condense the vapor bubbles 322 and return them to the liquid - cooling fluid 308.

[0024]

[0031] In one embodiment, the vaporization temperature of the cooling fluid can be adjusted by pressurizing the immersion chamber. For example, most fluids exhibit an increase in vaporization temperature with increasing pressure. In one embodiment, the cooling fluid can be pressurized to raise the vaporization temperature. In one embodiment, the cooling fluid can be dynamically pressurized in response to a dry-out condition. For example, a vapor sensor, such as an optical sensor that measures light scattering in the cooling fluid, can measure the vapor-to-liquid ratio. When the vapor-to-liquid ratio exceeds a threshold, the pressure increase in the immersion chamber (and, accordingly, the pressure increase on the cooling fluid) raises the vaporization temperature of the cooling fluid. Subsequently, the temperature of the liquid cooling fluid further increases, and the effectiveness of cooling the heat-generating component temporarily decreases, but the increase in vaporization temperature can suppress the formation of vapor and prevent the dry-out effect from compounding and worsening the situation.

[0025]

[0032] In one embodiment, a combination of a vapor diffuser, a micro condenser, and other devices can be used to control the vapor-to-liquid ratio of the cooling fluid in the cooling region. For example, the vapor diffuser can be used to divert vapor away from the heat-generating component and direct it towards the micro condenser. In other examples, the vapor diffuser can also direct vapor towards a nucleation rod or plate, which promotes the formation of vapor bubbles outside the cooling region. This allows heat to be removed from the liquid cooling fluid without increasing the vapor-to-liquid ratio in the cooling region.

[0026]

[0033] FIG. 5 shows an example of an immersion cooling system 400. In this system 400, a nucleation rod 424 is disposed laterally between a continuum of heat-generating components 414. The nucleation rod 424 promotes the formation of vapor bubbles 418 in the liquid cooling fluid 408 surrounding the heat-generating components 414. The vapor bubbles 418 can then rise through the liquid cooling fluid 408 in the direction of the vapor flow without colliding with the heat-generating components 414.

[0027]

[0034] In one embodiment, a thermal control device applied to an individual heat - generating component, such as a heat sink, cooling fins, a heat pipe, a vapor chamber, or other heat transfer device, can promote the vaporization of the liquid - cooling fluid by the individual heat - generating component at a specific location in the immersion tank. FIG. 6 shows an embodiment including a first heat - generating component 514 - 1 and a first heat transfer device 526 - 1 having a first width 528 - 1 in a vertical stack. The first heat transfer device 526 - 1 laterally transfers energy to a heat sink 530 - 1 or other device that promotes the formation of vapor bubbles 518 at a first lateral position that is separated from the first heat - generating component 514 - 1 by the first width 528 - 1. The second heat - generating component 514 - 2 is located above the first heat - generating component in the vertical stack and has a second heat transfer device 526 - 2 with a second width 528 - 2. The second heat transfer device 526 - 2 promotes vapor formation at the second width such that the second heat sink 530 - 2 does not enter the vapor path of the first heat transfer device 526 - 1 or the first heat sink 530 - 1. Thus, the vaporization of the cooling fluid 508 is promoted without causing a dry - out effect on subsequent heat - generating components, heat transfer devices, or heat sinks.

[0028]

[0035] In other examples, a continuum of heat - generating components can be disposed in a cooling fluid such that each heat - generating component in the continuum is laterally displaced from the immediately preceding heat - generating component. In one embodiment, the continuum is oriented at an angle with respect to the direction of the vapor flow, and each heat - generating component in the continuum vaporizes the cooling fluid into a different vertical vapor path. In a densely packed cooling system, a vapor diffuser can separate each continuum from one another and prevent the vapor generated by the heat - generating components of the first continuum from causing dry - out in the heat - generating components of the second continuum.

[0029]

[0036] FIG. 7 depicts an embodiment of an immersion cooling system 600 having a plurality of heat generating components 614 arranged in angled continua. Each continuum is oriented at an angle with respect to the direction of the vapor flow such that a first heat generating component 614-1 and a second heat generating component 614-2 do not laterally overlap each other (e.g., the vertical flow path from the first heat generating component 614-1 does not coincide with the second heat generating component 614-2). Vapor bubbles 618 generated by the heat of the first heat generating component 614-1 rise upward within the liquid cooling fluid 608. In some embodiments, a vapor diffuser 620 can direct the vapor bubbles 618 away from the continua of other heat generating components 614 and suppress and / or prevent a dry-out effect on adjacent continua.

[0030]

[0037] In embodiments of an immersion cooling system having heat generating components that include computing components, like computing components can be grouped into a stack or continuum. For example, a first continuum of heat generating components may be a graphics processing unit (GPU), and a second continuum of heat generating components may be a central processing unit (CPU). In other examples, a first immersion cooling system houses a GPU and a second immersion cooling system houses a CPU. Industrial Application Field

[0038] The present disclosure generally relates to thermal management systems and methods for electronic devices or other heat generating components. An immersion chamber surrounds a heat generating component within a liquid cooling fluid, and the liquid cooling fluid removes heat from the heat generating component to cool the heat generating component. As the cooling fluid absorbs heat from the heat generating component, the temperature of the cooling fluid rises, and the cooling fluid may vaporize, introducing vapor into the liquid of the cooling fluid.

[0031]

[0039] In one embodiment, thermal management of a heat-generating component includes removing or managing vapor in a cooling zone of a cooling fluid proximate to the heat-generating component. As the amount of vapor increases within the cooling zone, the thermal conductivity and thermal mass of the cooling fluid in the cooling zone decrease. The resulting effect is known as dryout. As a result of dryout, the thermal management capacity of the cooling zone decreases, and there is a risk that the temperature of the heat-generating component may rise to an undesirable and / or uncontrollable level.

[0032]

[0040] In one embodiment, dryout can be suppressed and / or prevented by one or more uses of the systems and / or methods described herein. Vaporization of the cooling fluid requires thermal energy to overcome the latent heat of vaporization, and in addition to convective cooling by the liquid cooling fluid, a certain amount of vaporization enables removal of thermal energy. By enabling vaporization that does not allow a dryout condition, thermal management can be improved.

[0033]

[0041] The immersion cooling system according to the present disclosure includes a chamber that houses a cooling fluid therein. A condenser is disposed above the liquid cooling fluid, in the upper portion of the cooling fluid, and in the vapor region of the cooling fluid. The condenser cools a portion of the vapor of the cooling fluid back to the liquid phase, removes thermal energy from the system, and reintroduces the cooling fluid into the immersion bath of the liquid cooling fluid.

[0034]

[0042] In one embodiment, the immersion tank of the liquid cooling fluid has a plurality of heat generating components disposed within the liquid cooling fluid. The liquid cooling fluid can surround the heat generating components and can also surround other objects or portions attached to the heat generating components. In one embodiment, the heat generating components are disposed on one or more supports within the liquid cooling fluid. The support supports one or more heat generating components within the liquid cooling fluid and can move the cooling fluid around the heat generating components. In one embodiment, the support is thermally conductive to remove heat from the heat generating components. The support(s) can increase the effective surface area of one or more of the heat generating components from which the cooling fluid can remove heat by convective cooling and, in one embodiment, includes a heat sink or other device attached to the heat generating component to rob thermal energy and effectively increase the surface area of the heat generating component.

[0035]

[0043] As described above, the conversion of the liquid cooling fluid to the gas phase requires an input of thermal energy to overcome the latent heat of vaporization and can be an effective mechanism for increasing the heat capacity of the cooling fluid and removing heat from the heat generating components. The formation of vapor bubbles in the liquid cooling fluid is not uniform in conventional immersion cooling systems. In conventional systems with vertically aligned heat generating components, equal heat generation by the heat generating components causes vaporization of the cooling fluid along the vertical stack of heat generating components. Since vapor rises in the liquid cooling fluid, the higher the heat generating component located in the vertical stack, the higher the vapor-to-liquid ratio in the region of the cooling fluid directly surrounding the heat generating component. This is because the liquid cooling fluid vaporizes near the heat generating components and the vapor bubbles rise within the liquid cooling fluid from a lower position.

[0036]

[0044] In certain embodiments according to the present disclosure, a thermal management system of a computing device includes one or more mechanisms for removing vapor from a cooling region of a cooling fluid that directly surrounds a heat - generating component. The cooling region is the region of the cooling fluid that directly surrounds the heat - generating component (including both liquid and vapor phases) and is the region of the cooling fluid responsible for convective cooling of the heat - generating component. In certain embodiments, the cooling region is the region of the cooling fluid within 5 millimeters (mm) of the heat - generating component. The cooling region is, in certain embodiments, the region of the cooling fluid within 5 mm of a vertical stack (support and heat - generating component). In certain embodiments, the cooling region is defined by a vertical cylinder surrounding each of the vertical stacks, and no part of this cylinder enters within 5 mm of the heat - generating component.

[0037]

[0045] The immersion cooling system described herein includes one or more mechanisms for removing vapor from the cooling region and maintaining a vapor - to - liquid ratio below a target value even when the heat - generating component is operating at maximum load. In certain embodiments, when the heat - generating component is operating at maximum load, less than 50% vapor remains in the cooling region. In certain embodiments, when the heat - generating component is operating at maximum load, less than 25% vapor remains in the cooling region. In certain embodiments, when the heat - generating component is operating at maximum load, less than 15% vapor remains in the cooling region. In certain embodiments, when the heat - generating component is operating at maximum load, less than 10% vapor remains in the cooling region. In certain embodiments, when the heat - generating component is operating at maximum load, less than 5% vapor remains in the cooling region.

[0038]

[0046] The cooling fluid has a boiling point lower than the critical temperature at which heat damage occurs to the heat-generating component. For example, the heat-generating component may be a computing device that is damaged when it is higher than 100 degrees Celsius (°C). In certain embodiments, the boiling point of the cooling fluid is less than the critical temperature of the heat-generating component. In certain embodiments, the boiling point of the cooling fluid is less than about 90 °C. In certain embodiments, the boiling point of the cooling fluid is less than about 80 °C. In certain embodiments, the boiling point of the cooling fluid is less than about 70 °C. The cooling fluid includes water in certain embodiments. The cooling fluid includes glycol in certain embodiments. The cooling fluid includes a combination of water and glycol in certain embodiments. The cooling fluid is an aqueous solution in certain embodiments. The cooling liquid is an electronic liquid such as FC-72 available from 3M or a similar non-conductive fluid in certain embodiments. In certain embodiments, the heat-generating component, the support, or other elements of the immersion cooling system disposed within the cooling fluid have nucleation sites on their surfaces and promote nucleation of vapor bubbles of the cooling fluid at temperatures below the boiling point of the cooling fluid.

[0039]

[0047] In certain embodiments, the immersion cooling system includes one or more mechanisms for discharging vapor from the cooling zone to reduce and / or maintain the vapor-to-liquid ratio. Within the immersion tank, an angled vapor diffuser may be disposed above one or more of the heat-generating components. The vapor diffuser is angled with respect to the direction of the vapor flow (i.e., vertically upward) such that vapor bubbles generated by the heat-generating component strike the angled vapor diffuser and are laterally biased as the vapor bubbles rise through the liquid due to the relative buoyancy of the vapor.

[0040]

[0048] In one embodiment, at least one vapor diffuser is flush with a surface oriented at a constant angle with respect to the direction of the vapor flow, and the vapor flow crosses this surface. In one embodiment, the at least one vapor diffuser has a plurality of surfaces (or curved surfaces), a portion of the vapor diffuser is oriented at a first angle, a portion of the vapor diffuser is oriented at a different second angle, and the vapor bubbles are induced in different lateral directions. In one example, the vapor diffuser is V-shaped, and a portion of the vapor generated by the heating component is induced in a first lateral direction and another portion of the vapor is induced in a second lateral direction. In one embodiment, the vapor diffuser directs all of the vapor generated by the associated heating component in a first direction. In one embodiment, the vapor diffuser directs approximately half of the vapor in a first direction and half of this vapor in a second direction.

[0041]

[0049] In one embodiment, a combination of the outer shapes of the vapor diffusers can be used to move the vapor bubbles away from the vertical stack or continuum of the heating components and disperse them throughout the immersion chamber. For example, at least one of the vapor diffusers can be oriented at a first angle with respect to the direction of the vapor flow, and a second vapor diffuser can be oriented at a second angle with respect to the direction of the vapor flow. In one example, the immersion cooling system includes at least one vapor diffuser having one plane and a second vapor diffuser having a plurality of planes and / or curved surfaces.

[0042]

[0050] The steam diffuser can further vary the spatial orientation within the immersion chamber in three dimensions. For example, in a continuum of heating components, the first heating component may have a first steam diffuser disposed above the first heating component, and the second heating component disposed above the first heating component in the continuum may have a second steam diffuser disposed above the second heating component. The first steam diffuser and the second steam diffuser can be oriented at the same angle (e.g., 30°) with respect to the direction of the steam flow, but can also be oriented in different lateral directions such that the first steam diffuser directs steam bubbles to the right side of the continuum of heating components and the second steam diffuser directs steam bubbles to the left side of the continuum of heating components. In one example, yet another steam diffuser in the continuum can also direct steam bubbles forward and / or backward (perpendicular to the first and second steam diffusers).

[0043]

[0051] In one embodiment, the vapor diffuser has different textures on the bottom surface and the top surface. For example, the bottom surface can be made smooth, or smoother than the top surface, to allow vapor bubbles to flow along the bottom surface without being hindered. The top surface may have a texture with greater undulations than the bottom surface, such as a nucleation site, or a rougher, wavy, or irregular texture than the bottom surface. The textured top surface can prevent rising bubbles from floating up and adhering to the top surface around the edge of the vapor diffuser when the bubbles float up. Further, the textured top surface can encourage any bubbles formed on this top surface to more easily break away from the top surface and not remain captured on the surface of the top surface. In one embodiment, the edge of the vapor diffuser includes one or more release features to encourage bubbles to be discharged upward in the direction of the vapor flow, adhere closely to the edge, and otherwise not remain on the edge and impede the flow. For example, the release feature may include an irregular or non-linear edge that suppresses the formation of vortices, so that the bubbles are not captured in the vortices in the edge flow and can be pushed away toward the top surface of the vapor diffuser.

[0044]

[0052] The vapor diffuser can cause the immersion chamber to change the vapor flow path from above the upward direction of the vapor flow. By inducing the vapor path to move away from the cooling region, the immersion cooling system can control the vapor-to-liquid ratio in the cooling region and enhance the cooling efficiency. The thermal control device can locally adjust the fluid temperature to control the vapor-to-liquid ratio in the cooling region and enhance the cooling efficiency.

[0045]

[0053] In one embodiment, a micro - capacitor is disposed within the immersion tank of the liquid - cooling fluid. The micro - capacitor can lower the temperature of the cooling fluid below the vaporization temperature in order to condense the vapor within the immersion tank and return it to the liquid phase. The micro - capacitor is, in one embodiment, a solid - state cooler, such as a Peltier cooler. In one embodiment, the micro - capacitor includes conduits for passing a secondary cooling fluid (e.g., refrigerant) through the micro - capacitor, and the secondary cooling fluid is at a lower temperature than the cooling fluid of the immersion tank. In one embodiment, the micro - capacitor is at least 2 millimeters from the surface of the heat - generating component.

[0046]

[0054] In one embodiment, the vaporization temperature of the cooling fluid can be adjusted by pressurizing the immersion chamber. For example, most fluids exhibit an increase in vaporization temperature with an increase in pressure. In one embodiment, the cooling fluid can be pressurized to raise the vaporization temperature. In one embodiment, the cooling fluid can be dynamically pressurized in response to a dry - out condition. For example, a vapor sensor, such as an optical sensor that measures the scattering of light in the cooling fluid, can measure the vapor - to - liquid ratio. When the vapor - to - liquid ratio exceeds a threshold value, an increase in pressure within the immersion chamber (and, accordingly, an increase in the pressure applied to the cooling fluid) raises the vaporization temperature of the cooling fluid. Then, the temperature of the liquid - cooling fluid further increases, and the effectiveness of cooling the heat - generating component temporarily decreases, but the increase in vaporization temperature can suppress the formation of vapor and prevent the dry - out effect that would exacerbate the situation.

[0047]

[0055] In one embodiment, a combination of a vapor diffuser, a micro condenser, and other devices can be used to control the vapor-to-liquid ratio of the cooling fluid in the cooling region. For example, the vapor diffuser can be used to direct vapor away from the heat-generating component and towards the micro condenser. In other examples, the vapor diffuser can also direct vapor towards a nucleation rod or plate, which promotes the formation of vapor bubbles outside the cooling region. This allows heat to be removed from the liquid cooling fluid without increasing the vapor-to-liquid ratio in the cooling region.

[0048]

[0056] In one embodiment, a thermal control device applied to an individual heat-generating component, such as a heat sink, cooling fins, a heat pipe, a vapor chamber, or other heat transfer device, can promote the vaporization of the liquid cooling fluid by the individual heat-generating component at a specific location in the immersion tank. For example, the first heat-generating component in a vertical stack can have a first heat transfer device with a first width. The first heat transfer device transfers energy laterally towards the heat sink or towards another device that promotes vapor formation at a first lateral position that is separated from the first heat-generating component by the first width. The second heat-generating component located above the first heat-generating component in the vertical stack has a second heat transfer device with a second width. The second heat transfer device promotes vapor formation at the second width such that the second heat transfer device does not enter the vapor path of the first heat transfer device. Thus, the vaporization of the cooling fluid is promoted without causing a dry-out effect on subsequent heat transfer devices.

[0049]

[0057] In other examples, a continuum of heat generating components can be disposed within a cooling fluid such that each heat generating component in the continuum is displaced laterally from the immediately preceding heat generating component. In certain embodiments, the continuum is oriented at an angle with respect to the direction of the vapor flow and cooling fluid is vaporized into different perpendicular vapor paths at each heat generating component in the continuum. In a closely packed cooling system, a vapor diffuser can separate each continuum from one another and prevent the vapor generated by the heat generating components of a first continuum from causing dryout at the heat generating components of a second continuum.

[0050]

[0058] In embodiments of an immersion cooling system having heat generating components that include computing components, like computing components can be grouped into a stack or continuum. For example, the heat generating components of a first continuum may be graphical processing units (GPUs) and the heat generating components of a second continuum may be central processing units (CPUs). In other examples, a first immersion cooling system houses a GPU and a second immersion cooling system houses a CPU.

[0051]

[0059] The present disclosure relates to systems and methods for removing vapor from a cooling zone and maintaining a vapor-to-liquid ratio below a target value, according to at least the examples set forth in the following items.

[0052] 1. A thermal management system for a computing device, comprising: an immersion chamber; a cooling fluid filling at least a portion of the immersion chamber; a plurality of heat generating components disposed within the cooling fluid and arranged in a continuum, the continuum defining a cooling zone of the cooling fluid in contact with the plurality of heat generating components for cooling the plurality of heat generating components; and means for removing vapor from the cooling zone of the cooling fluid.

[0053] 2. The system of item 1, wherein the means for removing vapor includes a vapor diffuser.

[0054] 3. In the system of item 1 or 2, the means for removing steam includes a thermal control device.

[0055] 4. In the system of item 3, the thermal control device is a condenser rod.

[0056] 5. In the system of any of the preceding items, the means for removing steam includes a nucleation source outside the cooling region.

[0057] 6. In the system of any of the preceding items, the cooling fluid includes glycol.

[0058] 7. A system according to any of the preceding items, further comprising a condenser disposed outside the cooling fluid in the immersion chamber.

[0059] 8. In the system of any of the preceding items, the immersion chamber is pressurized higher than atmospheric pressure.

[0060] 9. In the system of any of the preceding items, at least one of the plurality of heat generating components includes a heat sink disposed in the cooling fluid.

[0061] 10. In the system of item 9, the first heat generating component has a first heat sink of a first width, and the second heat generating component is located above the first heat generating component in the direction of the steam flow and has a second heat sink of a second width narrower than the first width.

[0062] 11. In the system of any of the preceding items, the cooling fluid has a boiling point of less than 90 degrees Celsius.

[0063] 12. In the system of any of the preceding items, the plurality of heat generating components includes a vertical stack of heat generating components, and the vertical stack of heat generating components consists of a central processing unit.

[0064] 13. In the system of any of the preceding items, the average liquid-to-vapor ratio in the cooling region is between 5% and 50%.

[0065] 14. In any of the systems of the preceding items, the cooling zone is within 5 millimeters of the continuum.

[0066] 15. In any of the systems of the preceding items, the continuum is oriented at an angle with respect to the direction of the vapor flow.

[0067]

[0060] The articles "a", "an", and "the" are intended to mean that there is one or more of the elements in the immediately preceding description. The terms "comprising", "including", and "having" are intended to be inclusive and mean that there may be additional elements other than the recited elements. Additionally, when referring to "one embodiment" or "an embodiment" of the present disclosure, it is not intended to exclude the existence of additional embodiments that incorporate the described features as well. For example, any of the elements described in relation to an embodiment herein may be combined with any of the elements of any other embodiment described herein. The numbers, percentages, ratios, or other values recited herein are intended to include that value and also other values that are "about" or "approximately" that recited value, as would be recognized by one of ordinary skill in the art in the technical field encompassed by the embodiments of the present disclosure. Accordingly, the recited values should be construed broadly enough to include at least values that are sufficiently close to the recited value to perform the desired function or achieve the desired result. The recited values should include at least the variations expected in a suitable manufacturing or production process and may include values that fall within 5%, 1%, 0.1%, or 0.01% of the recited value.

[0068]

[0061] Moreover, in view of the present disclosure, it should be recognized by those skilled in the art that equivalent structures do not depart from the gist and scope of the present disclosure, and that various changes, exchanges, and alterations can be made to the embodiments disclosed herein without departing from the gist and scope of the present disclosure. Equivalent structures including functional “means-plus-function” clauses are intended to include within the scope the structures described herein as performing the recited functions, including both structural equivalents that operate in a similar manner and equivalent structures having the same function. Except for claims in which the phrase “means for” appears in connection with a related function, it is the express intention of the applicant not to rely on means-plus-function or other functional claiming for any claim. Each addition, deletion, and change to an embodiment shall be included by the claims if it falls within the meaning and scope of the claims.

[0069]

[0062] It should be understood that any of the directions or reference systems in the immediately preceding description are merely relative directions or movements. For example, whenever reference is made to “front” and “rear” or “upper end” and “lower end,” or “left” and “right,” it merely describes the relative position or movement of the relevant elements.

[0070]

[0063] The present disclosure can be embodied in other specific forms without departing from its gist or characteristics. The described embodiments are to be construed as illustrative and not restrictive. Therefore, the scope of the disclosure is indicated not by the above description but by the appended patent claims. Changes falling within the equivalent meaning and scope of the claims shall be included within the scope of the claims.

Claims

1. A thermal management system for a computing device, comprising: an immersion chamber; a cooling fluid having a vapor phase and a liquid phase, the cooling fluid including a liquid cooling fluid that fills at least a portion of the immersion chamber; a plurality of heat-generating components disposed within the liquid cooling fluid and arranged in a continuum, the continuum defining a cooling region, the heat-generating components; means for removing vapor from the cooling region; wherein: the cooling region is within 5 millimeters of the continuum, and the means for removing vapor includes, outside the cooling region, a nucleation source that promotes nucleation of vapor bubbles of the cooling fluid, a thermal management system for a computing device.

2. The system according to claim 1, wherein the means for removing vapor includes a vapor diffuser.

3. The system according to claim 1 or 2, wherein the means for removing vapor includes a thermal control device.

4. The system according to claim 3, wherein the thermal control device is a condenser rod.

5. The system according to any one of claims 1 to 4, wherein the cooling fluid includes glycol.

6. The system according to any one of claims 1 to 5, further comprising a condenser disposed outside the liquid cooling fluid within the immersion chamber.

7. The system according to any one of claims 1 to 6, wherein the immersion chamber is pressurized higher than atmospheric pressure.

8. The system according to any one of claims 1 to 7, wherein at least one of the plurality of heat-generating components includes a heat sink disposed within the liquid cooling fluid.

9. The system according to claim 8, wherein a first heat-generating component has a first heat sink of a first width, and a second heat-generating component disposed above the first heat-generating component in the direction of the vapor flow has a second heat sink of a second width that is narrower than the first width.

10. The system according to any one of claims 1 to 9, wherein the cooling fluid has a boiling point lower than 90 degrees Celsius.

11. The system according to any one of claims 1 to 10, wherein the plurality of heat-generating components includes a vertical stack of heat-generating components, and the vertical stack of heat-generating components consists of a central processing unit, the system.

12. The system according to any one of claims 1 to 11, wherein an average liquid-to-vapor ratio in the cooling region is between 5% and 50%, the system.

13. The system according to any one of claims 1 to 12, wherein the continuum is oriented at an angle with respect to the direction of the vapor flow, the system.

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