Cooling Systems and Heat Exchangers

Abstract

An embodiment of the present application relates to a heat exchanger. The heat exchanger may include a plurality of flow paths configured for flow of a working fluid. The plurality of flow paths may be configured to move between a non-expanded configuration and an expanded configuration. In the non-expanded configuration, the plurality of flow paths are sized to allow movement of the heat exchanger relative to the one or more heat sources, and in the expanded configuration, the plurality of flow paths are sized to limit movement of the heat exchanger relative to the one or more heat sources, and the plurality of flow paths are configured to cause a change in an internal pressure of the working fluid to cause the plurality of flow paths to move between the non-expanded configuration and the expanded configuration.

Description

[Technical Field]

[0001] TECHNICAL FIELD Embodiments of the present application relate to cooling systems and heat exchangers. Some embodiments of the present application relate to evaporators and heat exchangers as part of a cooling system for a data center containing multiple electronic devices such as servers and other hardware components. [Background technology]

[0002] Cooling is essential for the proper operation of telecommunications and computing systems, so efficient cooling systems that consume less energy, require less active control, and lower costs are advantageous. Summary of the Invention

[0003] According to various (but not necessarily all) embodiments of the present disclosure, a heat exchanger may be provided, the heat exchanger may include a plurality of flow paths configured to carry a working fluid, the plurality of flow paths configured to move between an unexpanded configuration and an expanded configuration, wherein in the unexpanded configuration, the plurality of flow paths are sized to allow movement of the heat exchanger relative to the one or more heat sources, and in the expanded configuration, the plurality of flow paths are sized to limit movement of the heat exchanger relative to the one or more heat sources, and wherein changes in internal pressure of the working fluid cause the plurality of flow paths to move between the unexpanded configuration and the expanded configuration.

[0004] The plurality of channels may be substantially planar.

[0005] The plurality of flow paths may be configured to be disposed between substantially planar heat sources. The heat exchanger may be configured such that, when the plurality of flow paths are in an unexpanded configuration and disposed between one or more of the heat sources, a gap is provided between the heat source and the plurality of flow paths.

[0006] The heat exchanger may be configured such that when the plurality of flow paths are in an expanded configuration and positioned between one or more of the heat sources, the plurality of tubes grip the heat sources.

[0007] A thermal interface material may be coupled to the plurality of channels.

[0008] The plurality of channels may include a plurality of interior walls configured to provide a plurality of sub-channels, the plurality of interior walls including means for enabling expansion of the interior walls as the plurality of channels move between the unexpanded configuration and the expanded configuration.

[0009] The heat exchanger may include at least one header configured to facilitate cooling of one or more heat sources.

[0010] According to various (but not necessarily all) embodiments of the present application, a cooling system may be provided that includes a plurality of heat exchangers as described herein.

[0011] The cooling system may be used to cool hardware components.

[0012] The cooling system may include one or more intermediate heat exchangers that include a reservoir for storing a working fluid.

[0013] The reservoir may be coupled to an outlet of the intermediate heat exchanger.

[0014] The heat exchanger may be removably coupled to the cooling system.

[0015] The cooling system may be coupled to an air-cooling system, and the air-cooling system may include one or more fans configured to drive airflow through the air-cooling system toward a two-phase cooling system.

[0016] The two-phase cooling system may be configured to recover heat from the air cooling system. [Brief explanation of the drawings]

[0017] Some embodiments will now be described with reference to the accompanying drawings. [Figure 1] 1 is a schematic diagram illustrating a two-phase cooling system according to an embodiment. [Figure 2A] FIG. 2 is a schematic diagram showing an evaporator according to an embodiment. [Figure 2B] FIG. 2 is a schematic diagram showing an evaporator according to an embodiment. [Figure 3A] FIG. 2 is a schematic diagram showing a flow path of an evaporator according to an embodiment. [Figure 3B] FIG. 2 is a schematic diagram showing a flow path of an evaporator according to an embodiment. [Figure 3C] FIG. 2 is a schematic diagram showing a flow path of an evaporator according to an embodiment. [Figure 3D] FIG. 2 is a schematic diagram showing a flow path of an evaporator according to an embodiment. [Figure 4] 1 is a schematic diagram illustrating a cooling system according to an embodiment. [Figure 5A] FIG. 1 is a schematic diagram showing a heat exchanger according to an embodiment. [Figure 5B] FIG. 1 is a schematic diagram showing a heat exchanger according to an embodiment. [Figure 5C] FIG. 1 is a schematic diagram showing a heat exchanger according to an embodiment. [Figure 6A] FIG. 1 is a schematic diagram illustrating an evaporator and a high-speed junction coupled to a rack-level manifold according to an embodiment. [Figure 6B] FIG. 1 is a schematic diagram illustrating an evaporator and a high-speed junction coupled to a rack-level manifold according to an embodiment. [Figure 7A] FIG. 1 is a schematic diagram illustrating a cooling system for hardware components according to an embodiment. [Figure 7B] FIG. 1 is a schematic diagram illustrating a cooling system for hardware components according to an embodiment. [Figure 7C] FIG. 1 is a schematic diagram illustrating a cooling system for hardware components according to an embodiment. [Figure 8A] FIG. 10 is a schematic diagram illustrating a cooling system for hardware components according to another embodiment. [Figure 8B] FIG. 10 is a schematic diagram illustrating a cooling system for hardware components according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1 is a schematic diagram illustrating a passive two-phase refrigeration system including an evaporator 103 according to some embodiments of the present application. It should be understood that the refrigeration system disclosed herein is also compatible with active single-phase and two-phase embodiments in which a pump or other mechanical driver is used to circulate the working fluid.

[0019] 1, the two-phase refrigeration system 101 includes a thermosiphon loop that is driven by gravity rather than a pump. The heat exchanger and evaporator 103 according to the disclosed embodiments may be implemented in other types of two-phase refrigeration systems 101 in other embodiments of the present application.

[0020] 1 includes an evaporator 103, a condenser 105, a downcomer 107, and an upcomer 109. A working fluid 113 is provided within the thermosiphon loop. When the thermosiphon loop is in use, the working fluid 113 circulates through the components of the thermosiphon loop.

[0021] The evaporator 103 is located at the bottom of the thermosiphon loop so that the working fluid flows by gravity through the downcomer 107, as shown by arrow 115, and into the evaporator 103. The height and inner diameter of the downcomer 107 can be selected to set the thermosiphon driving force that causes fluid to flow through the evaporator 103, the riser 109, and the condenser 105. The working fluid 113 is in a liquid phase 117 at the inlet of the evaporator 103.

[0022] The evaporator 103 includes any means for transferring heat from a heat source 111 to the working fluid 113. The evaporator 103 is thermally coupled to the heat source 111. A thermal interface material may be used to enable the evaporator 103 to be thermally coupled to the heat source 111. The heat source 111 may include electronic equipment that generates unwanted heat during use. The electronic equipment may be a server, a router, a network switch, storage equipment, or any other suitable type of equipment. In some embodiments, these heat sources include a data center, a communications equipment room, or multiple electronic equipment that may provide a network, communications room, computer room, network room, or any other suitable arrangement.

[0023] Heat is transferred from the heat source 111 to the working fluid 113 in the evaporator 103, as indicated by arrow 119. This heat transfer causes a portion of the working fluid 113 to evaporate within the evaporator 103, converting the working fluid 113 from a liquid phase 117 to a mixture of liquid and vapor phases. Specifically, the evaporator 103 converts a portion of the working fluid 113 to a vapor phase 121 while retaining a portion in the liquid phase 117, resulting in a two-phase mixture exiting the evaporator 103. Heat transfer within the evaporator 103 is a combination of sensible and latent heat. The mass fraction of vapor 121 at the exit of the evaporator 103 is determined by the vapor quality factor. The two-phase mixture may include droplets of vapor entrained within a liquid or other flow regime, depending on the thermosiphon loop design, heat load, charge ratio, and other suitable parameters. The evaporator 103 is coupled to a riser 109 such that working fluid discharged from the evaporator 103 flows from the evaporator 103 into the riser 109. The working fluid comprises a two-phase mixture in which the vapor phase 121 is less dense than the liquid phase 117. As indicated by arrow 123, the working fluid 113 in the thermosiphon loop rises through the riser 109. Passive flow in the thermosiphon loop is driven by the density difference between the liquid phase working fluid 113 in the downcomer 107 and the two-phase mixture working fluid 113 in the riser 109.

[0024] The evaporator 103 may include structures that enable efficient heat transfer from the evaporator 103 to the working fluid 113. For example, the evaporator 103 may include a wick structure, microchannels, an array of fins, a serpentine arrangement of macro / microchannels, or any suitable combination of these elements.

[0025] The condenser 105 is located at the top of the thermosiphon loop and is positioned above the evaporator 103 such that the working fluid 113 flows upward from the evaporator 103 to the condenser 105.

[0026] The condenser 105 is coupled to the riser 109 such that the working fluid 113 in the two-phase mixture (vapor phase 121 and liquid phase 117) enters the condenser 105 from the riser 109. The condenser 105 may include any means for cooling the working fluid 113. For example, the condenser 105 may be air-cooled or liquid-cooled. A liquid-cooled condenser 105 may include a tube-in-tube heat exchanger, a shell-and-tube heat exchanger, a plate heat exchanger, or any other suitable heat exchanger configuration or arrangement. An air-cooled condenser 105 may include a louvered fin flat tube heat exchanger, a tube-and-fin heat exchanger, or any other suitable heat exchanger configuration or arrangement. The condenser 105 may include any suitable shape capable of efficiently removing heat from the working fluid.

[0027] The condenser 105 is thermally coupled to the coolant 125. A thermal interface material may be used to enable the condenser 105 to be thermally coupled to the coolant 125. The embodiments described below can also be used to enable hot-swappability of hardware by installing a reworkable thermal interface material connecting the two flows of the condenser 105. In other embodiments, the coolant 125 may be directly integrated into the condenser 105 with a wall interface separating the working fluid 113 flow from the coolant 125 flow. The wall interface may include a highly conductive metal or metal alloy, such as copper, aluminum, brass, or any other suitable metal. In some embodiments, the wall interface may include a highly conductive ceramic, such as aluminum nitride (AlN), or a polymer, such as a filled polymer composite.

[0028] The condenser 105 allows heat transfer from the working fluid 113 to the coolant 125, as indicated by arrow 127. This heat transfer causes the working fluid 113 to at least partially condense and return to the liquid phase 117. Thus, the working fluid 113 at the outlet of the condenser 105 may be in the liquid phase 117 or a two-phase mixture (vapor phase 121 and liquid phase 117).

[0029] The condenser 105 is coupled to the downcomer 107 such that the working fluid 113 flows by gravity down the downcomer 107 and back to the inlet of the evaporator 103 .

[0030] 2A and 2B are schematic diagrams illustrating a heat exchanger 200 according to some embodiments of the present application. In this embodiment, the heat exchanger 200 is an evaporator 103. The evaporator 103 can be used in refrigeration systems such as the two-phase refrigeration system 101 shown in FIG. 1. It should be understood that the evaporator 103 shown in FIGS. 2A and 2B can also be used in active single-phase and two-phase refrigeration systems in which a pump or other mechanical driver is used to circulate the working fluid.

[0031] The evaporator 103 may be used to cool memory boards, GPU cards, and / or other flat or substantially flat components of hardware or other heat sources. The cooled components may be used in telecommunications systems, computing systems, or any other suitable systems. In the embodiment of FIGS. 2A and 2B, the evaporator 103 is shown positioned adjacent to a memory board 203. In the embodiment of FIGS. 2A and 2B, the evaporator 103 is configured to enable cooling of a stack of the memory boards 203. A gap is provided between adjacent memory boards 203, and a portion of the evaporator 103 is configured to be disposed in the gap between the adjacent memory boards 203.

[0032] The evaporator 103 includes a plurality of flow paths 201. The flow paths 201 are configured to permit the flow of working fluid 113. The flow paths 201 provide a conduit or conduits for the working fluid 113 between an inlet manifold and an outlet manifold. In this example, the inlet manifold is the downcomer 107 of the two-phase refrigeration system 101, and the outlet manifold is the riser 109 of the two-phase refrigeration system 101. In the example of Figures 2A and 2B, the working fluid 113 flows through the flow paths 201 in the direction indicated by arrows 209.

[0033] The plurality of flow paths 201 are configured to allow heat from one or more heat sources 111 to be transferred to the working fluid 113 within the plurality of flow paths 201. In the embodiment of Figures 2A and 2B, the memory substrate 203 and components on the memory substrate 203 provide the heat source 111 (shown in Figure 1). The plurality of flow paths 201 are sized and shaped to be positioned sufficiently close to the memory substrate 203 such that heat from the memory substrate 203 is transferred to the working fluid 113 within the flow paths 201.

[0034] The flow channels 201 may be flat or substantially flat. The flow channels 201 may be shaped such that the height of the flow channels 201 is much smaller than the width of the flow channels 201. This allows for efficient heat transfer from the memory substrate 203 to the working fluid 113 within the flow channels 201. This allows the multiple flow channels 201 to be disposed in the gap between adjacent memory substrates 203.

[0035] The channel 201 may be sized to cover or substantially cover a surface of the memory substrate 203. In some embodiments, the channel 201 may be sized and shaped such that the surface area of ​​a planar side of the channel 201 covers or substantially covers the memory substrate 203, thereby allowing heat from multiple different components on the memory substrate 203 to be transferred into the working fluid 113.

[0036] In some embodiments of the present application, the plurality of channels 201 are expandable so as to move between an unexpanded configuration and an expanded configuration. FIG. 2A illustrates an evaporator 201 having the plurality of channels 201 in an unexpanded configuration. In this embodiment, the working fluid pressure is slightly higher than ambient pressure in the unexpanded configuration. In other embodiments, the working fluid pressure may be the same as or substantially the same as ambient pressure in the unexpanded configuration. FIG. 2B illustrates the plurality of channels 201 in an expanded configuration. In this embodiment, the working fluid pressure is much higher than ambient pressure in the expanded configuration. An outer wall of the plurality of channels 201 may be configured to expand and contract so as to move the plurality of channels 201 between an expanded configuration and an unexpanded configuration. The outer wall of the plurality of channels 201 may be formed from any suitable material that allows for expansion of the plurality of channels 201.

[0037] 2A , when the plurality of channels 201 are in an unexpanded configuration, the plurality of channels 201 are sized to allow relative movement of the evaporator 103 with respect to the memory substrate 203 or other heat source 111. In this unexpanded configuration, a gap 207 is provided between the plurality of channels 201 and the memory substrate 203. The gap 207 provides an air gap between the channels 201 and the memory substrate 203 and allows the evaporator 103 to be inserted into and / or removed from a position adjacent to the memory substrate 203.

[0038] During use of the evaporator 103, when cooling the heat source 111 on the memory substrate 203, heat is transferred to the working fluid 113 within the plurality of channels 201. This causes the pressure of the working fluid 113 within the plurality of channels 201 to increase. When the internal pressure of the working fluid 113 increases above the fluid pressure at ambient temperature, this causes the channels 201 to expand. This causes the channels 201 to move from the unexpanded configuration shown in FIG. 2A to the expanded configuration shown in FIG. 2B.

[0039] 2B, when the evaporator 103 is in the expanded configuration, the channels 201 are sized to ensure good heat transfer between the heat source 111 of the memory substrate 203 and the working fluid 113 flowing within the evaporator 103. The enlarged channels 201 may also limit the relative movement of the evaporator 103 with respect to one or more heat sources 111 and the memory substrate 203.

[0040] As shown in FIG. 2B , in the expanded configuration, there is no gap between the flow channels 201 and the memory substrate 203. In this configuration, the flow channels 201 are in direct contact with the memory substrate 203, such that the flow channels 201, or at least a portion of the flow channels 201, contact the memory substrate 203. This limits the relative movement of the evaporator 103 with respect to the memory substrate 203 because the flow channels 201 grip the memory substrate 203 or other heat source 111. The flow channels 201 of the evaporator 103 can return to a non-expanded configuration. For example, when the memory substrate 203 is not in use and heat is not being transferred to the working fluid 113, this causes a pressure drop in the working fluid 113. This causes the flow channels 201 to contract and return to the non-expanded configuration when the evaporator 103 is disconnected from the thermosiphon loop 101. This allows the evaporator 103 to be removed from the memory stack for maintenance, repair, or other suitable purposes.

[0041] 2A and 2B, a thermal interface material 205 is coupled to the plurality of channels 201. The thermal interface material 205 is coupled to the outer walls of the channels 201, and is therefore disposed between the memory substrate 203 and the channels 201. The thermal interface material 205 may include a phase change material, a reworkable gad pad, or other suitable thermally conductive material.

[0042] The thermal interface material 205 may be provided on a flat or substantially flat surface of the flow channel 201 to provide good thermal conductivity across the entire surface area of ​​the memory substrate 203 .

[0043] It should be understood that the evaporator 103 may include components not shown in FIGS. 2A and 2B . For example, the evaporator 103 may include an inlet header and / or an outlet header. The inlet header and the outlet header may be configured to enable uniform flow distribution and stable heat transfer performance from the inlet to the outlet of the evaporator 103. The inlet header and the outlet header may be designed to meet the power requirements of the evaporator 103 and take into account the shape and spacing constraints of the cooled hardware. The inlet header and the outlet header of the evaporator 103 may have a circular, rectangular, or any other cross-sectional area and / or shape. The evaporator 103 may have a dedicated header if cooling one heat source or a shared header if cooling multiple heat sources.

[0044] 3A-3D illustrate an exemplary flow channel 201 for use in the evaporator 103 shown in FIGS. 2A and 2B, or any other suitable evaporator 103 or heat exchanger 200. FIG. 3A illustrates an example of a flow channel 201 configured to move between an expanded and a non-expanded configuration. The flow channel 201 is flat or substantially flat. The height "h" of the flow channel 201 is much less than the width "w" of the flow channel 201. This provides a low-profile flow channel 201 that allows for efficient heat transfer from the memory substrate 203 or other heat source 111 to the working fluid 113 within the flow channel 201. This also allows the multiple flow channels 201 to be positioned between the interstices of a stack of memory substrates 203.

[0045] The flow path 201 includes an outer wall 303. The outer wall 303 provides a closed flow path through which the working fluid 113 flows. The outer wall 303 may include a thermally conductive material to allow heat to be effectively transferred to the working fluid 113. The outer wall 303 may further include a material that is sufficiently flexible to allow the flow path 201 to move between the unexpanded configuration and the expanded configuration. In some embodiments, the outer wall 303 may include copper, aluminum, brass, or any other suitable material or combination of materials.

[0046] The flow channel 201 may include a plurality of interior walls 301. The interior walls 301 extend vertically across a height "h" of the flow channel 201. The interior walls 301 subdivide the flow channel 201 into a plurality of sub-flow channels 305. The sub-flow channels 305 provide a more efficient flow of the working fluid 113 within the flow channel 201 due to a lower pressure drop, thereby enabling efficient heat transfer. In the embodiment shown in FIG. 3A, the interior walls 301 are evenly distributed across the width "w" of the flow channel, so that the sub-flow channels 305 all have the same or similar size. In other embodiments, different configurations of the interior walls 301 and the sub-flow channels 305 may be used to optimize or substantially optimize flow distribution.

[0047] Figures 3B-3D show how the channel 201 is configured to allow movement between an unexpanded configuration and an expanded configuration, and show cross sections of the channel 201 at different stages of fabrication.

[0048] Figure 3B shows a cross section of the channel 201 shown in Figure 3A. In this embodiment, the channel 201 comprises a multi-port tube. The channel 201 comprises an outer wall 303 and a plurality of internal channels 305, which are formed from the inner wall 301. In Figure 3B, the channel 201 is in the expanded configuration. In this expanded configuration, the side edges 309 of the channel 201 have a convex shape such that they curve outward.

[0049] In Figure 3C, the inner wall 301 is configured with means for allowing expansion of the inner wall 301 as the channels 201 move between the unexpanded configuration and the expanded configuration. In the embodiment of Figure 3A, portions of the inner wall 301 are removed to form gaps 307 between portions of the inner wall 301. The gaps 307 allow movement of a lower portion of the inner wall 301 relative to an upper portion of the inner wall 301, thereby allowing expansion and contraction of the channels 201.

[0050] The gap 307 may be sized to allow relative movement of portions of the interior wall 301 while still providing efficient flow of working fluid 113 through the flow passage 201. The gap 307 in the interior wall 301 may be formed using any suitable method.

[0051] Once the gap 307 or other means for allowing expansion of the inner wall 301 is provided in the inner wall 301, a force can be applied to the channel 201 to contract the channel to the unexpanded configuration. In the example of Figure 3B, a horizontal force is applied to the side edges 309 of the channel 201 and a vertical force is applied to the top edge of the channel 201.

[0052] The applied force causes the channels 201 to contract to the unexpanded configuration, as shown in Figure 3D. In this unexpanded configuration, the side edges of the channels 201 are in a folded configuration 311, which reduces the height of the channels 201 and makes the channels 201 smaller. When the channels 201 are in the unexpanded configuration, the upper edges of the channels 201 are closer together, thereby reducing the size of the gaps 307 between portions of the interior walls 301.

[0053] 3D, the flow channels 201 can be moved to a position relative to a memory board or other similar heat source 111. During use of the hardware, heat from the heat source is transferred to the working fluid 113 within the flow channels 201, causing an increase in pressure within the working fluid, resulting in expansion of the flow channels 201 back to the expanded configuration, in which the folded side edges are at least partially unfolded.

[0054] FIG. 4 illustrates an exemplary two-phase cooling system 101 including an evaporator 103 having multiple flow paths 201, as shown in FIGS. 2A-3D. The two-phase cooling system 101 may be configured to be thermally coupled to a secondary cooling system. For example, the two-phase cooling system 101 may provide server-level cooling, while the secondary cooling system may provide rack-level and / or room-level cooling. The two-phase cooling system 101 may be fluidly isolated from the secondary cooling system to allow for the use of two different working fluids within each cooling system. The two-phase cooling system 101 may be used to cool any device that generates unwanted heat, typically in a telecommunications system, a computing system, or any other suitable type of system.

[0055] The two-phase cooling system 101 shown in Figure 4 is a low-height thermosyphon loop. The thermal performance of the thermosyphon loop may be controlled by selecting an appropriate working fluid 113. The selection of the appropriate working fluid may be based on a trade-off between thermal performance, cost, and robust operation.

[0056] The evaporator 103 of the two-phase cooling system 101 is thermally coupled to a heat source 111. The heat source 111 may include one or more memory boards 203 and / or any other suitable heat-generating components, such as CPUs, GPUs, TPUs, etc. The evaporator 103 may include multiple expandable channels 201 or wick structures, microchannels, fin arrays, serpentine arrangements of macro / microchannels, or any suitable combination of these elements. While not shown in FIG. 4 for clarity, the above configurations may be incorporated into the evaporator 103.

[0057] The evaporator 103 is coupled between the downcomer 107 and the riser 109 of the two-phase refrigeration system 101 such that working fluid 113 flows from the downcomer 107 through the flow path 201 of the evaporator 103 to the riser 109 as indicated by the arrows.

[0058] The two-phase cooling system 101 also includes an intermediate heat exchanger 401. The intermediate heat exchanger 401 allows the two-phase cooling system to be coupled to the secondary cooling system. The intermediate heat exchanger 401 may include means for allowing heat to be transferred from the two-phase cooling system 101 to the secondary cooling system. The secondary cooling system may be an air-cooled or liquid-cooled system.

[0059] 4, the intermediate heat exchanger 401 includes a condenser 105 and a rack-level evaporator 403. In the intermediate heat exchanger 401, the working fluid 113 from the two-phase cooling system 101 is condensed by the condenser 105 on the primary side, thereby transferring heat to the rack-level evaporator 403 on the secondary side of the intermediate heat exchanger 401.

[0060] The rack-level evaporator 403 becomes part of a rack-level cooling loop, which may be an active single-phase cooling system, a two-phase cooling system, or another passive two-phase cooling system such as that shown in Figure 1. As mentioned above, the thermosiphon loop and the rack-level cooling system may have the same or different types of working fluid 113.

[0061] The intermediate heat exchanger 401 may be located directly above the evaporator 103 as shown in Figure 4. In other embodiments, the intermediate heat exchanger 401 may be located in a different location. The location of the intermediate heat exchanger 401 relative to the evaporator 103 may be determined by refrigeration hardware. The location of the intermediate heat exchanger 401 relative to the evaporator 103 is determined by the geometry (diameter and length) of the downcomer pipe 107 and the riser pipe 109.

[0062] The condenser 105 is coupled between the riser pipe 109 and the downcomer pipe 107. The condenser 105 is a low-profile condenser 105 having a flat or substantially flat shape. The condenser 105 also includes a reservoir 405. The reservoir 405 may be configured to store working fluid 113 and optimize or substantially optimize thermal performance. The reservoir 405 may be machined directly into an outlet header of the condenser 105 or integrated along the downcomer pipe 107. The reservoir may have a circular, rectangular, or any other cross-sectional area and / or shape.

[0063] The rack-level evaporator 403 may include any means that allows for the transfer of heat from the condenser 105 to a secondary cooling system. The condenser 105 may include multiple wick structures, microchannels, an array of evaporator fins, a serpentine arrangement of macro / microchannels, or any suitable combination of these elements.

[0064] 5A-5C show in more detail an exemplary condenser 105. This exemplary condenser 105 may be provided in a two-phase refrigeration system 101, such as that shown in FIG. 4, or in any other suitable type of refrigeration system.

[0065] Figure 5A shows the intermediate heat exchanger 401, which includes the condenser 105 and the rack-level evaporator 403. Figure 5B is a top view of the condenser 105, and Figure 5C is a bottom view of the condenser 105.

[0066] In the embodiment of FIG. 5A , the rack-level evaporator 403 includes an inlet 501 and an outlet 503. The inlet 501 and the outlet 503 are located on opposite sides of the rack-level evaporator 403 to allow the working fluid 113 to flow through the rack-level evaporator 403. In the embodiment of FIG. 5A , the inlet 501 and the outlet 503 are configured to extend horizontally to allow the working fluid 113 to flow horizontally. This provides a low-profile rack-level evaporator 403 that reduces the size factor of the intermediate heat exchanger 401. This configuration provides a more versatile cooling system that may be used in a wider range of devices. Other configurations and arrangements of the inlet pipes 501 and the outlet pipes 503 may be used depending on the hardware being cooled.

[0067] The condenser 105 further includes an inlet port 507 and an outlet port 509 for the flow of the working fluid 113 .

[0068] The condenser 105 includes a reservoir 405 for storing the working fluid 113. In the embodiment of FIGS. 5A-5C, the reservoir 405 is coupled to the outlet header of the condenser 105. Locating the reservoir 405 in the outlet header of the condenser 105 rather than in the downcomer 107 can simplify the fabrication of the cooling system 101. Locating the reservoir 405 in the outlet header also ensures that the reservoir 405 is located at the highest point in the cooling system 101, resulting in optimal thermal performance. FIGS. 5A-5C further illustrate that the reservoir 405 may be designed with a fill port 505 for filling the cooling system 101 before use. The reservoir 405 in the condenser 105 can reduce subcooling of the working fluid 113, thereby preventing the condenser 105 from overflowing, which reduces the thermal efficiency of the cooling system.

[0069] FIG. 6A shows an evaporator 103 coupled to a rack manifold 609. The rack manifold 609 allows the evaporator 103 to be fluidly coupled to a condenser 105 and other components of a cooling system. The evaporator 103 may include multiple flow paths 201, as shown in FIGS. 2A-3D, or may be fabricated with any other suitable type of structure to enhance heat transfer. The evaporator 103 may be thermally coupled to a heat source 111 by a thermal interface material (not shown in FIG. 6A). The heat source may be a heat-generating component such as a memory board 203, CPUs, GPUs, TPUs, or any other suitable heat source.

[0070] The evaporator 103 is coupled to the rack manifold 609, which includes the downcomer pipes 107 and the riser pipes 109. The downcomer pipes 107 and the riser pipes 109 are configured to allow working fluid 113 to flow between the condenser 105 (not shown in FIG. 6A ) and the evaporator 103.

[0071] In the embodiment shown in FIG. 6A , means for removably coupling the evaporator 103 to the rack manifold 609 are provided on both the downcomer pipes 107 and the riser pipes 109. In this embodiment, this means is manifested by quick couplings on both the downcomer pipes 107 and the riser pipes 109. Other coupling means and / or coupling types may be used in other embodiments of the present application. This may allow the evaporator 103 to be removed from the rest of the cooling system 101 while the hardware is in use. This may provide a hot-swappable evaporator 103 or other heat exchanger 200.

[0072] 6B is a detailed schematic diagram of the usable quick coupling 601. The quick coupling 601 includes an adapter plug 603, a valve 605, and a housing 607. Depending on the operating conditions and system configuration, the quick coupling can be either blind-mate or hand-mate.

[0073] 7A and 7B are schematic diagrams illustrating the layout of a cooling system for multiple components to be cooled within target hardware 701. The cooling system may use passive two-phase flow as shown in FIG. 1. The cooling system includes multiple evaporators 103 with multiple flow channels 201 as shown in FIGS. 2A-3D. In some embodiments, the evaporators 103 may include wick structures, microchannels, an array of evaporator fins, a serpentine arrangement of macro / microchannels, or any suitable combination of these elements.

[0074] 7A and 7B, the hardware 701 includes a memory unit 703 and a processing unit 705. In the example, the hardware 701 includes four memory units 703 and two processing units 705. Other arrangements and configurations of components within the hardware 701 may be used in other embodiments of the present application.

[0075] The memory unit 703 may include a stack of memory substrates 203. The expandable flow channel 201 of the evaporator 103 may be disposed in the gap between adjacent memory substrates 203, thereby efficiently cooling the memory substrates 203. Additional evaporators 103 may be provided in the processing unit 705.

[0076] In the embodiment of Figure 7A, the two-phase refrigeration system 101 is configured such that the evaporators 103 are connected in series. The evaporators 103 are connected in series such that the working fluid 113 flows from the outlet of the first evaporator 103 to the inlet of the next evaporator 103 in the series. In this series arrangement, the working fluid 113 passes through each evaporator 103 in sequence.

[0077] 7A, the two-phase cooling system 101 includes two serial loops. The first serial loop includes an evaporator 103 for cooling a memory unit 703, and the second serial loop includes an evaporator 103 for cooling a processing unit 705. Other arrangements may be used in other embodiments of the present application depending on the hardware configuration and thermal design power of different components.

[0078] In the embodiment of FIG. 7B, the two-phase cooling system 101 is configured with the evaporators 103 connected in parallel. The evaporators 103 are connected in parallel so that the inlet and outlet of each evaporator 103 share a common server-level manifold. In this embodiment, the working fluid 113 at the server-level inlet manifold flows from the downcomer 107, while the working fluid 113 at the server-level outlet manifold flows to the riser 109. Other configurations may be used in other embodiments of the present application depending on the hardware configuration and thermal design power of different components. FIG. 7C shows an example of an evaporator 103 that may be used in cooling systems operating in single-phase and two-phase flow, and in active and passive modes, such as the two-phase cooling system 101 of FIGS. 7A and 7B.

[0079] The exemplary evaporator 103 includes a substrate 707 and a plurality of evaporator fins 709. The evaporator 103 further includes a cover plate (not shown in FIG. 7C) disposed over the substrate 707 and the evaporator fins 709.

[0080] The substrate 707 includes a flat or substantially flat surface. The substrate 707 may include a thermally conductive material. The substrate 707 may be thermally coupled to a heat source to allow heat to be transferred from the heat source to the working fluid 113 within the evaporator 103 during use of the evaporator 103.

[0081] The plurality of evaporator fins 709 extend from a surface of the substrate 707. At least a portion of the evaporator fins 709 define a flow path for the working fluid 113 through the evaporator 103.

[0082] In the embodiment of Figure 7C, the evaporator fins 709 include elongated structures that extend perpendicularly or substantially perpendicularly from the substrate 707. In the embodiment of Figure 7C, the evaporator fins 709 include elongated plates that extend parallel or substantially parallel across the surface of the substrate 707.

[0083] The evaporator fins 709 may comprise any suitable thermally conductive material. The evaporator fins 709 may comprise the same material as the base plate 707 and the cover plate.

[0084] 8A and 8B show alternative cooling system configurations that can be used to cool the subject hardware 701. In this embodiment, the hardware 701 includes four memory units 703 and two processing units 705. Other hardware configurations 701 may be used in other embodiments of the present application.

[0085] In one example of hardware 701 shown in Figure 8A, the evaporator 103 is located on the processing unit 705, while the memory unit 703 and other low-power components on the server board are cooled by an air-cooled heat sink 819. The evaporator 103 may include multiple wick structures, microchannels, an array of evaporator fins, a serpentine arrangement of macro / microchannels, or any suitable combination of these elements. Figure 7C shows an example of a microchannel that can be used.

[0086] The hardware 701 shown in FIG. 8A includes a hybrid cooling system, where the two processing units 705 are two-phase cooled, while other components such as memory units 703, substrates, and secondary chips are cooled by an air-cooling system.

[0087] The air cooling system is configured to draw cool air in at the front of the hardware 701, as indicated by arrows 801. The air then flows through different air-cooled heat sinks 819 located on hardware components, where it is heated by heat dissipation from the memory units 703 and other heat sources 111. The heated air is exhausted from the back of the hardware 701, as indicated by arrows 803.

[0088] In the embodiment shown in FIG. 8A , the hardware 701 includes a baffle 805. The baffle 805 may be an adjustable baffle and may be positioned around the memory unit 703 and other heat sources 111. The baffle 805 provides a means for directing airflow over the memory unit 703 and other air-cooled components to reduce pressure drop and maximize or substantially maximize the heat transfer provided by the air cooling. The arrows and baffle shown in FIG. 8A indicate uniform airflow over the hardware components. In other embodiments, additional baffles or other means for directing airflow may be positioned on the hardware 701 to provide increased airflow over the air-cooled components compared to other components that may be two-phase cooled or do not require specific cooling. Controlling the airflow is advantageous for improving energy efficiency and reducing noise levels.

[0089] A plurality of fans 809 are also provided at the rear of the hardware 701. The plurality of fans 809 are configured to draw air through the hardware 701. In the embodiment of Figure 8A, three fans 809 are provided. Other numbers of fans, other fan locations, and other air flow directions may be used in other embodiments of the present application.

[0090] In the embodiment shown in FIG. 8A, the hardware 701 further includes an additional cooling system 807. In this embodiment, the additional cooling system 807 may include a passive two-phase cooling system 101 as shown in FIG. 1. The additional cooling system 807 is configured to allow cooling of heated air drawn over the memory unit 703 and any other air-cooled components. Thus, the two-phase cooling system is configured to recover heat from the air-cooling system. The additional cooling system 807 is provided at the rear of the hardware 701 to allow cooling of air from the air-cooling system before it exits the hardware 701 and enters the ambient environment.

[0091] The additional cooling system 807 may include an evaporator 103 disposed between the downcomer 107 and the riser 109. Figure 8B shows a portion of the additional cooling system 807 and the evaporator 103 in more detail. The evaporator 103 may be connected to a rack manifold as described above, or may be connected using any other suitable connection.

[0092] The evaporator 103 of the additional cooling system 807 is located at the rear of the hardware 701 and includes an inlet 813 coupled to the downcomer 107. The inlet 813 can provide a single-phase working fluid 113 to the evaporator 103.

[0093] The working fluid 113 flows through the evaporator 103 as shown by arrows 817. The working fluid 113 is thereby heated by air drawn through the evaporator 103. The air may be drawn through the evaporator 103 by multiple fans in a fan tray 811. In this embodiment, three fans 809 are provided in the fan tray 811. Other numbers of fans 809, other fan locations, and other air flow directions may be used in other embodiments of the present application.

[0094] Heat transfer between the heated air and the working fluid 113 causes the working fluid 113 to partially boil, and the two-phase working fluid 113 is then discharged from the evaporator 807 through the outlet 815 and supplied to the riser 109.

[0095] The additional cooling system 807 may remove additional heat from the data center 701. This heat may be recovered and transferred for heating elsewhere or may be reused in waste heat recovery applications, thereby providing a more energy-efficient hardware 701. The embodiments shown in Figures 8A and 8B are suitable for use in data centers and other hardware environments that operate with traditional cooling methods, such as direct expansion, chilled water, free cooling with an evaporator, or other traditional cooling methods.

[0096] The additional cooling system 807 is also advantageous in mitigating hot spots that can occur in existing data centers when upgrading hardware with additional IT, telecommunications, and computing capabilities because room-level cooling infrastructure is sized for a given cooling capacity.

[0097] 8A and 8B, the cooling system 807 is in addition to the evaporator 103 used in the processing unit 705. In other embodiments, the additional cooling system 807 may be provided in hardware 701 without the primary evaporator 103, or in any other suitable configuration.

[0098] 8A and 8B , the additional cooling system 807 is configured to cool the air before it is exhausted from the hardware 701 to the ambient environment. In other embodiments, the additional cooling system 807 may be configured to recirculate the cooled air within the hardware 701 rather than exhausting it from the hardware 701. In this embodiment, baffles or other suitable means for directing air flow may be provided within the hardware 701. Recirculating air within the hardware 701 may reduce the heat exhausted to the environment surrounding the hardware 701, resulting in more efficient cooling and reduced overall energy consumption.

[0099] The term "comprises" as used herein is intended to be inclusive rather than exclusive, i.e., any reference to X containing Y indicates that X may contain only one Y or may contain two or more Ys.

[0100] Reference may be made herein to various embodiments. The description of a feature or function with respect to an embodiment indicates that the feature or function is present in that embodiment. References herein to "an embodiment," "for example," "may," or "may," whether explicitly stated or not, indicate that such feature or function is present in at least the described embodiment, whether or not it is listed as an example, and may, but need not, be present in some or all of the other embodiments. Thus, references herein to "an embodiment," "for example," "may," or "may," whether explicitly stated or not, indicate a particular embodiment within a class of embodiments. Properties of an embodiment may be properties of only that embodiment, properties of that class, or properties of a subclass of that class (including some, but not all, of the class). Thus, a feature described with reference to one embodiment and not described with reference to another embodiment is implicitly indicated to the extent possible, but not necessarily, to be used in other embodiments as part of a working combination.

[0101] Although the embodiments of the present application have been described in detail in the above paragraphs, the present application is not limited to the above embodiments, and it should be understood that any modifications, equivalent replacements, improvements, etc. made under the concept and principles of the present application are included in the scope of protection of the present application.

[0102] Features set out in the above description may be used in combinations other than those explicitly set out above.

[0103] Although functions have been described with reference to particular functions, those functions may be performed by other functions, whether or not described.

[0104] Although features have been described with reference to particular embodiments, those features may also be present in other embodiments, whether or not described.

[0105] The terms "a" and "the" used herein are inclusive rather than exclusive. That is, the phrase "X includes Y / said Y" used herein indicates that X may include only one Y or may include two or more Ys, unless the context clearly indicates otherwise. When using "a" or "the" with an exclusive meaning, the context must clearly indicate this. In some cases, the terms "at least one" or "one or more" may be used to emphasize an inclusive meaning, but the absence of these terms should not be considered as an inference of an exclusive meaning.

[0106] A feature (or combination of features) in a claim refers to the feature or (combination of features) itself, as well as features that can achieve substantially the same technical effect (equivalent features). Equivalent features include, for example, modified features that achieve substantially the same result in substantially the same way. Equivalent features include, for example, features that perform substantially the same function in substantially the same way to achieve substantially the same result.

[0107] Various embodiments may be referred to herein using adjectives or adjectival phrases to describe features of the embodiments. The description of a property with respect to an embodiment indicates that the property is, in some embodiments, specifically as described and, in other embodiments, substantially as described.

[0108] Although the foregoing specification has endeavored to draw attention to what are considered to be essential features, applicants should understand that they may seek protection through the claims to protect any patentable feature or combination of features shown in the above drawings and / or drawings, whether emphasized or not. [Explanation of symbols]

[0109] 101 Two-phase cooling system, thermosyphon loop, cooling system 103 Evaporator 105 Condenser, liquid-cooled condenser, thin condenser 107 Downcomer 109 Ascending Pipe 111 Heat source 113 Working fluids, single-phase working fluids, two-phase working fluids 117 Liquid phase 121 Vapor Phase 125 Coolant 200 heat exchanger 201 Flow path, channel, evaporator 203 Memory Board 205 Thermal interface materials 207 Gap 301 Interior wall 303 Exterior Wall 305 Sub-channel, internal channel 307 Gap 309 Side edge 311 Configuration 401 Intermediate heat exchanger 403 Rack level evaporator, Thin rack level evaporator 405 reservoir 501 Inlet, inlet pipe 503 Outlet, outlet pipe 505 Filling Port 507 Inlet Port 509 Exit Port 601 High speed coupling section 603 adapter plug 605 Valve 607 Case 609 Rack Manifold 701 Hardware, Data Center 703 Memory Unit 705 Processing Unit 707 Substrate 709 Evaporator fin 805 Baffle 807 Cooling System 809 Fan 811 Fan Tray 819 Air-cooled Heatsink

Claims

1. a plurality of flow paths configured to carry a working fluid, the plurality of flow paths configured to move between an unexpanded configuration and an expanded configuration, wherein in the unexpanded configuration, the plurality of flow paths are sized to allow movement of the heat exchanger relative to one or more heat sources, and in the expanded configuration, the plurality of flow paths are sized to restrict movement of the heat exchanger relative to the one or more heat sources, and wherein changes in internal pressure of the working fluid cause the plurality of flow paths to move between the unexpanded configuration and the expanded configuration; In the unexpanded configuration, for each of the plurality of channels, upper and lower edges are adjacent and side edges are in a folded configuration; the plurality of channels include a plurality of interior walls configured to provide a plurality of sub-channels evenly distributed across a width of the channels, the plurality of interior walls including means for enabling expansion of the interior walls as the plurality of channels move between the unexpanded configuration and the expanded configuration; heat exchanger.

2. the plurality of channels are substantially planar; The heat exchanger of claim 1 .

3. the plurality of channels are configured to be disposed between substantially planar heat sources; The heat exchanger of claim 1 .

4. the heat exchanger is configured such that, when the plurality of flow paths are in the unexpanded configuration and disposed between one or more of the heat sources, a gap is provided between the heat source and the plurality of flow paths. The heat exchanger of claim 1 .

5. the heat exchanger is configured such that when the plurality of flow paths are in the expanded configuration and the heat exchanger is disposed between one or more of the heat sources, the plurality of tubes grip the heat sources. The heat exchanger of claim 1 .

6. a thermal interface material coupled to the plurality of flow channels; The heat exchanger of claim 1 .

7. the heat exchanger including at least one header configured to enable cooling of one or more of the heat sources; The heat exchanger of claim 1 .

8. A heat exchanger according to any one of claims 1 to 7, Cooling system.

9. The cooling system is configured to include one or more hardware components used to cool the The cooling system of claim 8.

10. the cooling system includes one or more intermediate heat exchangers including a reservoir for storing the working fluid; The cooling system of claim 8.

11. the reservoir is coupled to the outlet of the intermediate heat exchanger; The cooling system of claim 10.

12. the heat exchanger is removably coupled to the cooling system; The cooling system of claim 8.

13. the cooling system is coupled to an air cooling system; The cooling system of claim 8.

14. the air-cooling system includes one or more fans configured to drive airflow through the air-cooling system toward a two-phase cooling system. The cooling system of claim 13.

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