A two-phase dual-layer interleaved enhanced microchannel heat sink

Abstract

The embodiment of the application provides a two-phase double-layer staggered reinforced micro-channel radiator, which comprises a stacked upper cold plate and a lower cold plate. A plurality of first fins and second fins arranged in an array are arranged in the upper cold plate and the lower cold plate respectively, so as to form a first micro-channel group in the upper cold plate and a second micro-channel group in the lower cold plate. The first micro-channel group and the second micro-channel group are respectively used for containing and guiding a cooling working medium to flow through the upper cold plate and the lower cold plate. The extension direction of the first fin is perpendicular to the extension direction of the second fin, so that the flow directions of the first micro-channel group and the second micro-channel group are arranged in a vertical staggered manner. The bottom wall of the first micro-channel group and the second micro-channel group along the thickness direction of the cold plate is further provided with a porous layer. Based on the synergistic optimization of the double-layer staggered micro-channel and the porous layer, the problems of dry-out phenomenon, flow instability and low heat exchange efficiency of the micro-channel radiator in a high heat flux density scene are effectively solved.

Description

Technical Field

[0001] This application relates to the field of heat dissipation technology for electronic devices, and in particular to a two-phase, double-layer, staggered reinforced microchannel heat sink. Background Technology

[0002] With the rapid development of electronic information technology toward high integration and high power density, the heat flux density of chips and other core heat-generating components continues to rise, far exceeding the limits of traditional heat dissipation technologies such as air cooling and liquid cooling.

[0003] In related technologies, microchannel heat sinks are used to cool electronic devices with high heat flux density. The microchannel heat sink has densely arranged microchannels inside, and the cooling medium is forced to convect within the microchannels to remove heat, thereby achieving ultra-high performance heat dissipation.

[0004] However, microchannel heat sinks in related technologies have the following problems: uneven distribution of cooling working fluid in the microchannels can easily lead to flow dead zones and local heat accumulation in specific areas, affecting heat dissipation performance; under high heat flux density conditions, excessive dryness of the two-phase working fluid at the channel outlet can easily cause the microchannel end to dry out, seriously threatening the operational reliability and lifespan of electronic devices. Summary of the Invention

[0005] This application provides a two-phase, double-layer, staggered reinforced microchannel heat sink to solve the problems of low heat dissipation efficiency and easy burn-out of microchannel heat sinks under high heat flux density conditions in related technologies.

[0006] In a first aspect, embodiments of this application provide a two-phase, double-layer, staggered reinforced microchannel heat sink, comprising: an upper cold plate; and a lower cold plate, wherein the lower cold plate is stacked along its thickness direction at the bottom of the upper cold plate and connected to the upper cold plate to form an integral structure; the upper cold plate and the lower cold plate are respectively provided with a plurality of arrayed first ribs and a plurality of arrayed second ribs to form a first microchannel group in the upper cold plate and a second microchannel group in the lower cold plate, the first microchannel group and the second microchannel group being respectively configured to accommodate and guide the cooling working fluid to flow through the upper cold plate and the lower cold plate; the extension direction of the first ribs is perpendicular to the extension direction of the second ribs, so that the flow directions of the first microchannel group and the second microchannel group are vertically staggered; the bottom wall of the first microchannel group and the second microchannel group along the thickness direction of the cold plate is further provided with a porous layer.

[0007] The two-phase, double-layer, staggered reinforced microchannel heat sink provided in this application embodiment has the following effects:

[0008] This application embodiment improves heat dissipation performance through a double-layer cold plate design. The heat source is located below the lower cold plate, and its heat is primarily absorbed by the lower cold plate. The remaining heat is conducted to the upper cold plate through the solid-solid contact interface between the two cold plates. The upper cold plate absorbs this remaining heat, thus sharing the heat load and assisting the lower cold plate in heat dissipation. Simultaneously, the cooling medium in the upper cold plate maintains a lower temperature during heat exchange, creating a significant temperature gradient between the two cold plates. This further enhances heat transfer from the lower cold plate to the upper cold plate. The cooling medium in the lower cold plate is cooled by the cooling medium in the upper cold plate, reducing the dryness of the two-phase fluid within the lower cold plate and promoting heat transfer from the core area of ​​the heat source to the two microchannels, thereby increasing heat dissipation power.

[0009] This application embodiment also optimizes the microchannel layout of the upper and lower cold plates, resulting in a vertically staggered arrangement of the two microchannels to form a vertically staggered upper and lower flow field structure. The upper and lower flow field structures work together to dissipate heat, optimize the flow field and temperature field distribution, reduce local heat accumulation, and further improve heat dissipation efficiency. The upper and lower cold plate microchannels respectively adopt a centrally connected structure and a gradually expanding structure along the flow path, realizing fluid mixing and redistribution and increasing the flow cross-sectional area, thereby reducing flow instability and flow resistance.

[0010] Meanwhile, this embodiment also incorporates a porous layer on the bottom wall of the microchannel. Each pore in the porous layer serves as a potential, highly efficient vaporization nucleus, thereby increasing the vaporization nucleus density, enhancing flow boiling heat transfer, advancing the boiling initiation point, reducing the wall temperature of the cold plate, increasing the critical heat flux density, and significantly suppressing the risk of burn-out. This solves the problems of easy burn-out and low upper limit of heat flux density in traditional single-layer microchannels, improving heat dissipation capacity by more than 100% under the same scale, and is particularly suitable for long-term stable cooling of high heat flux density electronic devices. Attached Figure Description

[0011] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0012] Figure 1 Schematic diagram of the structure of the two-phase double-layer staggered reinforced microchannel heat sink provided in this application Figure 1 ;

[0013] Figure 2 Schematic diagram of the upper cold plate of the two-phase double-layer staggered reinforced microchannel heat sink provided in this application Figure 1 ;

[0014] Figure 3 A schematic diagram of the lower cold plate of the two-phase, double-layer, staggered reinforced microchannel heat sink provided in this application;

[0015] Figure 4Schematic diagram of the structure of the two-phase double-layer staggered reinforced microchannel heat sink provided in this application Figure 2 ;

[0016] Figure 5 Schematic diagram of the upper cold plate of the two-phase double-layer staggered reinforced microchannel heat sink provided in this application Figure 2 .

[0017] Figure label:

[0018] 100 - Upper cold plate;

[0019] 101-First rib; 102-Upper substrate; 103-Cover plate; 104-Baffle;

[0020] 1021 - Upper liquid collection tank; 1024 - Inlet through hole; 1025 - Outlet through hole; 1031 - First inlet pipe; 1032 - First outlet pipe; 1033 - Second inlet pipe; 1034 - Second outlet pipe; 1041 - First sub-chamber; 1042 - Second sub-chamber; 1043 - Third sub-chamber; 1044 - Fourth sub-chamber; 1045 - Fifth sub-chamber;

[0021] 200 - Lower cold plate;

[0022] 201 - Second rib; 202 - Lower substrate;

[0023] 2021 - Lower liquid collection tank.

[0024] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0026] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0027] First, let me explain the terms used in this application:

[0028] Flow boiling heat transfer: refers to the technology that uses the phase change (boiling) of liquid in forced flow to achieve extremely high heat dissipation efficiency. Compared with single-phase liquid cooling, it has a higher heat transfer coefficient.

[0029] Vaporization nucleus density refers to the number of "nucleation points" on a unit area of ​​the heated wall surface that can effectively generate steam bubbles during the boiling heat transfer process. The higher the vaporization nucleus density, the more fully and evenly the heat exchange of the entire heating surface is activated, and the higher the overall heat transfer performance.

[0030] Boiling initiation point: refers to the instant when steam bubbles begin to be stably generated on the heated wall surface for the first time during the boiling heat transfer process; that is, the moment of transition from "no bubbles" to "bubbling". The boiling initiation point marks the transformation of the heat transfer mode from relatively low-performance single-phase liquid cooling to extremely high-performance nucleation boiling.

[0031] Heat flux density: the amount of heat transferred through a unit area per unit time.

[0032] Critical heat flux density refers to the critical heat load at which, when the heat flux density of a heated wall reaches a certain level, the rate of bubble formation becomes too rapid and excessive, resulting in a continuous vapor film on the wall surface. This causes a sharp decrease in heat transfer capacity and a rapid increase in wall temperature. It represents the theoretical maximum heat dissipation capacity of a cooling system. Maximizing the critical heat flux density can improve the heat dissipation limit and safety of the cooling system.

[0033] Drying out (or dehydration): This refers to the phenomenon in the boiling heat transfer process where the liquid is completely evaporated on the heating surface, causing steam to come into direct contact with the heating surface, which leads to a sharp deterioration in heat transfer and a sudden rise in wall temperature, potentially causing overheating and damage to the equipment.

[0034] refer to Figure 1 , Figure 2 and Figure 3 The two-phase, double-layer, staggered reinforced microchannel heat sink provided in this application embodiment includes: an upper cold plate 100 and a lower cold plate 200.

[0035] The lower cold plate 200 is stacked on the bottom of the upper cold plate 100 along its thickness direction (z-axis shown in the figure) and is connected to the upper cold plate 100 by diffusion welding or brazing to form an integral structure. The connection is reliably sealed to prevent leakage of the cooling medium.

[0036] Both the upper cold plate 100 and the lower cold plate 200 are made of materials with good thermal conductivity, such as copper, aluminum, and diamond.

[0037] The upper cold plate 100 includes an upper substrate 102. The upper substrate 102 has two upper liquid collection tanks 1021 disposed on its top surface along its thickness direction (z-axis shown in the figure). The two upper liquid collection tanks 1021 are spaced apart along the length direction of the cold plate (x-axis shown in the figure). A plurality of arrayed first ribs 101 are disposed between the two upper liquid collection tanks 1021 to form a first microchannel group in the upper cold plate 100. The first microchannel group is used to contain and guide the cooling working fluid to flow through the upper cold plate 100.

[0038] The first microchannel group is connected to both upper liquid collection tanks 1021.

[0039] The lower cold plate 200 includes a lower substrate 202. The lower substrate 202 has two lower liquid collection tanks 2021 disposed on its top surface along its thickness direction (z-axis shown in the figure). The two lower liquid collection tanks 2021 are spaced apart along the width direction of the cold plate (y-axis shown in the figure). A plurality of arrayed second ribs 201 are disposed between the two lower liquid collection tanks 2021 to form a second microchannel group in the lower cold plate 200. The second microchannel group is used to contain and guide the cooling working fluid to flow through the lower cold plate 200.

[0040] The second microchannel group and the two lower liquid collection tanks 2021 are all connected.

[0041] In other words, the overall structure formed by connecting the upper cold plate 100 and the lower cold plate 200 has two layers of cooling channels.

[0042] The first rib 101 extends along the length direction of the cold plate (x-axis shown in the figure), and the second rib 201 extends along the width direction of the cold plate (y-axis shown in the figure). That is, the extension direction of the first rib 101 is perpendicular to the extension direction of the second rib 201, so that the flow directions of the first microchannel group and the second microchannel group are arranged perpendicularly and alternately.

[0043] The bottom walls of the first and second microchannel groups along the thickness direction of the cold plate (z-axis shown in the figure) are also provided with porous layers.

[0044] This embodiment of the application improves heat dissipation performance through a double-layer cold plate design. The heat source is located below the lower cold plate 200, and its heat is primarily absorbed by the lower cold plate 200. The remaining heat is conducted to the upper cold plate 100 through the solid-state interface between the two cold plates. The upper cold plate 100 absorbs this remaining heat, thus sharing the heat load and assisting the lower cold plate 200 in heat dissipation. Simultaneously, the cooling medium in the upper cold plate 100 maintains a lower temperature during heat exchange, creating a significant temperature gradient between the two cold plates. This further enhances heat transfer from the lower cold plate 200 to the upper cold plate 100. The cooling medium in the lower cold plate 200 is cooled by the cooling medium in the upper cold plate 100, reducing the dryness of the two-phase fluid within the lower cold plate 200 and promoting heat transfer from the core area of ​​the heat source to the two microchannels, thereby increasing heat dissipation power.

[0045] This application embodiment also optimizes the microchannel layout of the upper and lower cold plates, so that the two layers of microchannels are arranged vertically and staggered to form a vertically staggered upper and lower two-layer flow field structure. The upper and lower two-layer flow field structures work together to dissipate heat, optimize the flow field and temperature field distribution, reduce local heat accumulation, and further improve the heat dissipation capacity.

[0046] Meanwhile, this embodiment also incorporates a porous layer on the bottom wall of the microchannel. Each pore in the porous layer serves as a potential, highly efficient vaporization nucleus, thereby increasing the vaporization nucleus density, enhancing flow boiling heat transfer, advancing the boiling initiation point, reducing the wall temperature of the cold plate, increasing the critical heat flux density, and significantly suppressing the risk of burn-out. This solves the problems of easy burn-out and low upper limit of heat flux density in traditional single-layer microchannels, improving heat dissipation capacity by more than 100% under the same scale, and is particularly suitable for long-term stable cooling of high heat flux density electronic devices.

[0047] In this embodiment, the cooling medium can be a low-boiling-point medium under normal or positive pressure, and the boiling point range of the cooling medium is 20℃-60℃.

[0048] In this embodiment, the first microchannel group is a serpentine flow channel structure.

[0049] A serpentine flow channel refers to a first microchannel group consisting of a series of long, parallel straight channels, with adjacent straight channels connected at their ends in sub-chambers, allowing the cooling medium to flow repeatedly along a single series path within the first microchannel group.

[0050] The serpentine flow channel has its inlet located downstream of the cooling medium flowing through the lower cold plate 200, and its outlet located upstream of the cooling medium flowing through the lower cold plate 200. The upper cold plate 100 changes the flow direction of the cooling medium through the serpentine flow channel design, allowing the cooling medium in the upper cold plate 100 to flow into the outlet area of ​​the lower cold plate 200, directly cooling the high dryness area at the outlet of the lower cold plate 200. This effectively reduces the dryness of the two-phase fluid at the outlet of the lower cold plate 200, preventing it from drying out and reducing flow instability.

[0051] refer to Figure 4 and Figure 5 In this embodiment of the application, a sealed upper liquid collection tank 1021 is provided in the upper cold plate 100.

[0052] The upper cold plate 100 has an upper liquid collection tank 1021, a first microchannel group, and another upper liquid collection tank 1021 arranged in sequence and connected. At least one baffle 104 is provided in each of the two upper liquid collection tanks 1021 to form a sub-chamber. The baffle 104 is used to guide the cooling working fluid flowing in the first microchannel group to flow along a serpentine path to form a serpentine flow channel.

[0053] One of the upper liquid collection tanks 1021 is equipped with a baffle 104, which divides the upper liquid collection tank 1021 into a first sub-chamber 1041 and a second sub-chamber 1042 adjacent along the width direction of the cold plate (y-axis shown in the figure); the other upper liquid collection tank 1021 is equipped with two baffles 104, which divide the upper liquid collection tank 1021 into a third sub-chamber 1043, a fourth sub-chamber 1044 and a fifth sub-chamber 1045 adjacent along the width direction of the cold plate (y-axis shown in the figure).

[0054] The third sub-chamber 1043 is located downstream of the cooling medium in the lower cold plate 200, and the fifth sub-chamber 1045 is located upstream of the cooling medium in the lower cold plate 200; the inlet of the serpentine flow channel is located in the third sub-chamber 1043, and the outlet of the serpentine flow channel is located in the fifth sub-chamber 1045.

[0055] The cooling medium flows in from the third sub-chamber 1043, passes through the microchannel corresponding to the third sub-chamber 1043, flows into the first sub-chamber 1041 and fills the first sub-chamber 1041, then passes through the microchannel corresponding to the first sub-chamber 1041 and flows into the fourth sub-chamber 1044, continues to pass through the microchannel corresponding to the fourth sub-chamber 1044 and flows into the second sub-chamber 1042 and fills the second sub-chamber 1042, and finally passes through the microchannel corresponding to the second sub-chamber 1042 and flows into the fifth sub-chamber 1045.

[0056] By setting baffles 104 in the upper cold plate 100, the cooling medium is guided to flow along a serpentine path by the baffles 104, which is simple and easy to implement. Moreover, those skilled in the art can increase or decrease the number of baffles 104 or adjust the setting position of the baffles 104 according to the actual heat dissipation scenario and the distribution of the first ribs 101.

[0057] It should be noted that the upper substrate 102, the baffle 104 and the multiple first ribs 101 can be integrally formed.

[0058] refer to Figure 4 and Figure 5 In this embodiment of the application, the upper cold plate 100 further includes a cover plate 103.

[0059] The cover plate 103 is stacked on the top surface of the upper substrate 102 to seal the groove and microchannel group of the upper liquid collection tank 1021, forming a closed flow channel in the upper cold plate 100.

[0060] The cover plate 103 can be sealed to the upper substrate 102 by welding or a detachable joint to ensure that the cooling fluid does not leak.

[0061] The cover plate 103 is provided with a first inlet pipe 1031, a first outlet pipe 1032, a second inlet pipe 1033, and a second outlet pipe 1034.

[0062] The first inlet pipe 1031 is located above the third sub-chamber 1043 along the thickness direction of the cold plate (z-axis shown in the figure), and the first inlet pipe 1031 is connected to the third sub-chamber 1043; the first outlet pipe 1032 is located above the fifth sub-chamber 1045 along the thickness direction of the cold plate (z-axis shown in the figure), and the first outlet pipe 1032 is connected to the fifth sub-chamber 1045; thus, the first inlet pipe 1031 and the first outlet pipe 1032 are respectively connected to the first microchannel group, and the cooling working fluid flows into the first microchannel group from the first inlet pipe 1031, and flows out from the first outlet pipe 1032 after completing the heat exchange.

[0063] The upper substrate 102 is also provided with an inlet through hole 1024 and an outlet through hole 1025. The inlet through hole 1024 and the outlet through hole 1025 are opposite each other along the width direction of the cold plate (y-axis shown in the figure). In the lower cold plate 200, a lower liquid collection tank 2021, a second microchannel group and another lower liquid collection tank 2021 are sequentially connected. The two ends of the inlet through hole 1024 along its axial direction are respectively connected to the second inlet pipe 1033 and a lower liquid collection tank 2021. The two ends of the outlet through hole 1025 along its axial direction are respectively connected to the second outlet pipe 1034 and another lower liquid collection tank 2021. The cooling working fluid flows from the second inlet pipe 1033 through the inlet through hole 1024 into the second microchannel group. After completing the heat exchange, it flows out from the second outlet pipe 1034 through the outlet through hole 1025.

[0064] In other words, two low-boiling-point cooling media are connected in parallel and flow into the upper cold plate 100 and the lower cold plate 200 respectively through separate pipes. One low-boiling-point cooling media flows directly into the microchannel of the upper cold plate 100 through the inlet pipe of the cover plate 103, while the other low-boiling-point cooling media flows sequentially through the inlet pipe of the cover plate 103 and the inlet through-hole 1024 of the upper cold plate 100 before entering the microchannel of the lower cold plate 200. During the flow process, the low-boiling-point cooling media exchange heat with the cold plates to form a two-phase fluid. Finally, the two two-phase fluids flow out from the upper cold plate 100 and the lower cold plate 200 respectively, and exit through the outlet pipe on the cover plate 103, completing the cooling process.

[0065] It should be noted that the inlet area of ​​the upper cold plate 100 corresponds to the outlet area of ​​the lower cold plate 200, and the outlet area of ​​the upper cold plate 100 corresponds to the inlet area of ​​the lower cold plate 200, forming a combination of interleaved flow and counterflow, which reduces the dryness of the outlet of the lower cold plate 200.

[0066] Meanwhile, the cooling medium of the lower cold plate 200 is introduced and drawn out through the inlet and outlet holes opened on the upper cold plate 100, and the overall structure is highly integrated.

[0067] The cascading scenario in this application embodiment is as follows:

[0068] The first outlet pipe 1032 is connected to the second inlet pipe 1033. The low-boiling-point cooling medium flowing out of the upper cold plate 100 continues to enter the lower cold plate 200 through the second inlet pipe 1033, completing the series cooling and heat exchange of the two cold plates. The low-boiling-point cooling medium first enters the upper cold plate 100 for subcooling boiling heat exchange, and then enters the lower cold plate 200 for saturated boiling heat exchange.

[0069] In this embodiment, the porous layer is formed by sintering and solidifying copper powder particles with a particle size of 50μm to 150μm or copper wire mesh with a mesh size of 150 mesh to 300 mesh.

[0070] The preparation process of the porous layer is as follows:

[0071] First, copper powder particles with a particle size of 50μm to 150μm or copper wire mesh with a mesh size of 150 mesh to 300 mesh are placed in a concave mold and sintered and cured at 850℃ to form a structure with the same size as the first microchannel group and the second microchannel group. Then, the cured porous layer is placed on the bottom wall of the first microchannel group and the second microchannel group, pressed with a convex mold, and then sintered in a diffusion welding furnace or sintering furnace at 850℃ for 90 minutes to completely fix the porous layer to the bottom wall of the first microchannel group and the second microchannel group, achieving a tight bond and ensuring heat transfer performance.

[0072] Copper has excellent thermal conductivity. When copper powder particles with a particle size of 50μm to 150μm are used, the porous layer formed by sintering has the best capillary force, which can ensure that the liquid can flow smoothly inside the porous layer, while allowing the generated steam bubbles to easily detach and escape.

[0073] When using 150-300 mesh copper wire mesh, the sintered body can generate sufficiently strong capillary force to ensure a continuous and stable supply of liquid to the evaporation interface, and also has sufficiently high permeability to allow steam bubbles to escape efficiently.

[0074] The thickness of the porous layer, formed by sintering and solidifying copper powder particles or copper wire mesh, can be 0.3mm to 0.8mm. This ensures the porous layer possesses strong and timely capillary pumping capabilities to prevent drying out.

[0075] In this embodiment, the porous layer may also consist of multiple arrayed microfins, with the height of the microfins along the thickness direction of the cold plate being 0.1mm to 0.14mm. This ensures that the porous layer possesses strong and timely capillary pumping capability to suppress burn-out.

[0076] In this embodiment, the porosity of the porous layer is 40%~60%.

[0077] Porosity refers to the percentage of the volume of pores within a porous material relative to the total volume of the material.

[0078] Porous layers within the aforementioned porosity range exhibit excellent capillary force. During boiling, this strong capillary force can continuously and autonomously transport the liquid working fluid in the main channel to the wall area that urgently needs replenishment due to violent evaporation, achieving a good liquid replenishment effect and increasing heat flux density.

[0079] The porous layer has a uniform pore size distribution, which greatly increases the vaporization nuclei, enabling the low-boiling-point working fluid at normal pressure or at positive pressure to boil earlier.

[0080] In this embodiment, the porosity of the porous layer increases along the direction pointing towards the heat source to be dissipated.

[0081] The high-porosity region is close to the heat source side, providing a large number of vaporization nuclei and ensuring that the boiling initiation point is advanced, which greatly enhances the phase change heat transfer process. The low-porosity region is close to the outlet side, and the finer and denser pore network has greater capillary pressure, which can continuously "pull" the liquid in the main channel toward the high-porosity region that is evaporating violently, ensuring that the liquid is efficiently replenished to the region with higher dryness and preventing it from being burned dry.

[0082] In this embodiment, the cross-section of the first rib 101 and the second rib 201 is a rectangular cross-section. That is, the first microchannel group and the second microchannel group are both composed of a series of parallel straight channels, which facilitates processing and ensures uniform heat dissipation of the cooling medium.

[0083] In this embodiment, the projection of the first microchannel group on the thickness direction of the cold plate (the z-axis shown in the figure) coincides with the projection of the second microchannel group on the thickness direction of the cold plate (the z-axis shown in the figure).

[0084] The shape, structure, and size of the first microchannel group are the same as those of the second microchannel group. The first microchannel group and the second microchannel group are directly opposite each other in the thickness direction of the cold plate (the z-axis shown in the figure). They have the same projected heat transfer area, ensuring that the upper cold plate 100 can achieve the purpose of assisting the lower cold plate 200 in heat dissipation.

[0085] In this embodiment, the thickness of the first rib 101 and the second rib 201 is the first thickness; the distance between two adjacent first ribs 101 and the distance between two adjacent second ribs 201 are the first spacing; the height of the first rib 101 and the second rib 201 along the thickness direction of the cold plate is the first height; wherein, the first thickness, the first spacing and the first height are the same, and the first thickness, the first spacing and the first height are all 1 mm to 2 mm.

[0086] In this embodiment, the first thickness, first spacing, and first height may also be different, and those skilled in the art can set them according to the actual application scenario.

[0087] In this embodiment, one of the sidewalls of the outlet channels of the first microchannel group and the second microchannel group has a stepped step. The height of the stepped step in the thickness direction of the cold plate (z-axis shown in the figure) gradually decreases along the flow direction of the cooling medium, so that the outlet channel gradually expands along the flow direction of the cooling medium.

[0088] The outlet flow channel gradually expands along the flow direction of the cooling medium, allowing the cooling medium to obtain sufficient diffusion space in the outlet region. This effectively reduces the pressure drop and flow resistance of the gas-liquid mixture at the outlet, and improves flow stability.

[0089] The following detailed description of the two-phase, double-layer, staggered, reinforced microchannel heat sink according to specific embodiments of this application is provided:

[0090] The microchannel heat sink consists of a cover plate 103, an upper cold plate 100, and a lower cold plate 200. The cover plate 103, the upper cold plate 100, and the lower cold plate 200 are made of copper and are formed into a complete closed structure through precision diffusion welding.

[0091] In this embodiment, vacuum diffusion welding technology is used to complete the connection of each layer. The welding surfaces of the cover plate 103, the upper cold plate 100 and the lower cold plate 200 are ground with a grinding wheel, and the surface roughness is controlled within Ra1.6 μm to remove the surface oxide layer and impurities. The overall deviation does not exceed 1%, the welding temperature is controlled at 850℃, and the vacuum degree is maintained below 5×10-3 Pa.

[0092] The cover plate 103 is 6 mm thick, and the upper cold plate 100 and the lower cold plate 200 are 10 mm thick. The surfaces of the cover plate 103, the upper cold plate 100 and the lower cold plate 200 are all precision milled to ensure that the flatness is high enough to guarantee the welding seal.

[0093] The first inlet pipe 1031, the first outlet pipe 1032, the second inlet pipe 1033, and the second outlet pipe 1034 have a diameter of 8 mm and are welded to the cover plate 103 to realize the inlet and outlet flow of the cooling working fluid.

[0094] The first microchannel group of the upper cold plate 100 and the second microchannel group of the lower cold plate 200 are effective heat dissipation areas. The distribution area of ​​the first microchannel group of the upper cold plate 100 and the distribution area of ​​the second microchannel group of the lower cold plate 200 are both 32mm×50mm, and the first microchannel group and the second microchannel group are aligned.

[0095] The cross-sectional dimensions of the first rib 101 forming the first microchannel group and the second rib 201 forming the second microchannel group are both 1 mm wide and 1.5 mm high. The first microchannel group of the upper cold plate 100 has a length of 50 mm in the length direction of the cold plate (x-axis shown in the figure) and a total of 16 first ribs 101. The second microchannel group of the lower cold plate 200 has a width of 32 mm in the width direction of the cold plate (y-axis shown in the figure) and a total of 25 second ribs 201, forming a vertically interlaced flow field structure.

[0096] Both the first and second microchannel groups have porous layers made of sintered copper powder on their bottom walls along the thickness direction of the cold plate (z-axis shown in the figure). The copper powder with a particle size of 50μm is sintered at 850℃, with a thickness of 0.5mm and a porosity of 60%. It is bonded to the bottom walls of the first and second microchannel groups through diffusion welding.

[0097] The working process of this microchannel heat sink is as follows:

[0098] Two low-boiling-point cooling media are connected in parallel and their flow rates are individually controlled by the first inlet pipe 1031, the first outlet pipe 1032, the second inlet pipe 1033, and the second outlet pipe 1034. After entering the two low-boiling-point cooling media from the first inlet pipe 1031 and the second inlet pipe 1033 respectively, one flows directly into the first microchannel group of the upper cold plate 100, flows along the length direction, and flows out after heat exchange; the other flows through the inlet through hole 1024 (diameter 8 mm, bottom plate liquid collection tank width is 10 mm) of the upper cold plate 100 into the second microchannel group of the lower cold plate 200, flows along the width direction, and flows out through the outlet through hole 1025 after heat exchange.

[0099] During the flow within the two layers of cold plates, on one hand, the low-boiling-point cooling working fluid undergoes forced convection boiling heat exchange with the cold plates. The copper powder sintered porous layer at the bottom of the microchannel provides a large number of vaporization nuclei, prompting the working fluid to begin boiling at a relatively low wall temperature. On the other hand, the capillary force of the porous layer continuously replenishes the vaporization nuclei with liquid, preventing the risk of burn-out due to increased dryness. Simultaneously, the upper cold plate 100 assists the lower cold plate 200 in completing the heat exchange process. Finally, the low-boiling-point two-phase working fluid flows out from the upper cold plate 100 and the lower cold plate 200, respectively, completing the cooling process.

[0100] Specifically, the heat source is located below the lower cold plate 200, and its heat is mainly absorbed by the lower cold plate 200. Some of the heat can be conducted to the upper cold plate 100 through the solid contact interface between the two cold plates. The low-boiling-point working fluid flowing in the upper cold plate 100 can promptly conduct this part of the heat, directly sharing the heat load of the lower cold plate 200. At the same time, the low-boiling-point working fluid in the upper cold plate 100 maintains a low temperature during the heat exchange process, forming a significant temperature gradient between the two cold plates, further enhancing the heat transfer from the lower cold plate 200 to the upper layer. The low-boiling-point working fluid in the lower cold plate 200 is cooled by the low-boiling-point working fluid in the upper cold plate 100, reducing the dryness of the two-phase fluid in the lower cold plate 200, promoting the transfer of heat from the core area of ​​the heat source to the two layers of cold microchannels, and improving the heat dissipation power.

[0101] Finally, the staggered microchannels of the two cold plates change the distribution of the flow field and temperature field, effectively reducing the local heat flow concentration of the lower cold plate 200, and forming a synergistic heat dissipation effect with the flow of the working fluid, ultimately achieving efficient assistance for heat exchange of the lower cold plate 200.

[0102] Performance tests show that this two-phase, double-layer staggered reinforced microchannel radiator exhibits excellent heat dissipation performance under test conditions such as using low-boiling-point working fluid at normal pressure and high-pressure refrigerant: with an effective heat dissipation area of ​​32 mm × 50 mm, the heating power generated when the fluid is burned out is over 2400 W and 3000 W respectively, and the critical heat flux density reaches over 200 W / cm2 and 260 W / cm2 respectively, which is more than 100% higher than the traditional single-layer microchannel structure; when the heat flux density is 50~200 W / cm2, the double-layer staggered microchannel structure reduces the wall temperature by a maximum of 5-10℃ compared to the traditional single-layer microchannel structure; under the same operating conditions, the double-layer staggered microchannel structure greatly improves flow instability and reduces temperature fluctuation by at least 40% compared to the traditional single-layer microchannel structure.

[0103] This embodiment is applicable to the cooling of high heat flux density electronic devices, and is particularly suitable for cooling high heat flux density chips (such as 1000W-2600W GPUs). In practical applications, by adjusting the flow distribution ratio of the first inlet pipe 1031, the first outlet pipe 1032, the second inlet pipe 1033, and the second outlet pipe 1034, precise matching of heat load in different areas can be achieved.

[0104] Test data shows that when the local heat flux density of the chip suddenly increases to 260 W / cm2, the system can still maintain stable operation without any burn-out phenomenon.

[0105] It should be noted that although the embodiments of this application are applied to high-power chip heat dissipation scenarios, the technical solutions of the embodiments of this application are also applicable to the heat dissipation needs of other high-power electronic devices, such as power MOSFETs, CPUs, GPUs, etc. Any modified applications based on the basic design concept of this embodiment, as long as they adopt the core technical features of this invention, should fall within the protection scope of this application.

[0106] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A two-phase, double-layer, staggered reinforced microchannel heat sink, characterized in that, include: Upper cold plate (100); as well as The lower cold plate (200) is stacked on the bottom of the upper cold plate (100) along its thickness direction and connected to the upper cold plate (100) to form an integral structure; The upper cold plate (100) and the lower cold plate (200) are respectively provided with a plurality of arrayed first ribs (101) and a plurality of arrayed second ribs (201) to form a first microchannel group in the upper cold plate (100) and a second microchannel group in the lower cold plate (200). The first microchannel group and the second microchannel group are respectively configured to contain and guide the cooling working fluid to flow through the upper cold plate (100) and the lower cold plate (200). The extension direction of the first rib (101) is perpendicular to the extension direction of the second rib (201), so that the flow directions of the first microchannel group and the second microchannel group are arranged perpendicularly and alternately. The bottom walls of the first microchannel group and the second microchannel group along the thickness direction of the cold plate are also provided with a porous layer; The first microchannel group of the upper cold plate (100) is a serpentine flow channel. The inlet of the serpentine flow channel is close to the downstream of the cooling medium flowing through the lower cold plate (200), and the outlet of the serpentine flow channel is close to the upstream of the cooling medium flowing through the lower cold plate (200).

2. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The upper cold plate (100) is provided with two upper liquid collection tanks (1021). A plurality of first ribs (101) are disposed between the two upper liquid collection tanks (1021), and the two ends of the plurality of first ribs (101) extend toward the two upper liquid collection tanks (1021) respectively along their extension direction; At least one baffle (104) is provided in each of the two upper liquid collection tanks (1021). The baffle (104) is used to guide the cooling working fluid flowing in the upper cold plate (100) along a serpentine path to form the serpentine flow channel.

3. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 2, characterized in that, The upper cold plate (100) includes: The upper substrate (102) has two upper liquid collection tanks (1021) on its top surface along the thickness direction of the cold plate. A cover plate (103) is stacked on the top surface of the upper substrate (102) to close the two upper liquid collection tanks (1021). The cover plate (103) is provided with a first inlet pipe (1031), a first outlet pipe (1032), a second inlet pipe (1033), and a second outlet pipe (1034). The first inlet pipe (1031) and the first outlet pipe (1032) are respectively connected to the two upper liquid collection tanks (1021) so that one of the cooling working fluids flows through the first microchannel group. The lower cold plate (200) is provided with two lower liquid collection tanks (2021), and a plurality of second ribs (201) are provided between the two lower liquid collection tanks (2021). The two ends of the plurality of second ribs (201) extend toward the two lower liquid collection tanks (2021) respectively along their extension direction. The upper substrate (102) is provided with an inlet through hole (1024) and an outlet through hole (1025). The two ends of the inlet through hole (1024) along its axial direction are respectively connected to the second inlet pipe (1033) and a lower liquid collection tank (2021). The two ends of the outlet through hole (1025) along its axial direction are respectively connected to the second outlet pipe (1034) and another lower liquid collection tank (2021), so that another cooling working fluid flows through the second microchannel group. The upper cold plate (100) and the lower cold plate (200) are connected in parallel.

4. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 3, characterized in that, The first outlet pipe (1032) and the second inlet pipe (1033) are connected, and the cooling medium flowing out from the upper cold plate (100) flows into the lower cold plate (200). The upper cold plate (100) and the lower cold plate (200) are connected in series.

5. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The porous layer is formed by sintering and solidifying copper powder particles with a particle size of 50μm to 150μm or copper wire mesh with a mesh size of 150 mesh to 300 mesh, and the thickness of the porous layer is 0.3mm to 0.8mm; or, The porous layer consists of multiple arrayed microfins, the height of which along the thickness direction of the cold plate is 0.1mm-0.14mm.

6. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The porosity of the porous layer is 40% to 60%.

7. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The porosity of the porous layer increases along the direction pointing towards the heat source to be dissipated.

8. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The cross-sections of the first rib (101) and the second rib (201) are rectangular.

9. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The projection of the first microchannel group in the thickness direction of the cold plate coincides with the projection of the second microchannel group in the thickness direction of the cold plate.

10. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The thickness of the first rib (101) and the second rib (201) is the first thickness; The distance between two adjacent first ribs (101) and the distance between two adjacent second ribs (201) constitute the first distance; The height of the first rib (101) and the second rib (201) along the thickness direction of the cold plate is the first height; The first thickness, the first spacing, and the first height may be the same or different.

11. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, One of the sidewalls of the outlet flow channels of the first microchannel group and the second microchannel group has a stepped step. The height of the stepped step in the thickness direction of the cold plate gradually decreases along the flow direction of the cooling medium, so that the outlet flow channel gradually expands along the flow direction of the cooling medium.

12. The two-phase, double-layer, staggered reinforced microchannel heat sink according to claim 1, characterized in that, The cooling medium is a low-boiling-point medium under normal or positive pressure, and the boiling point range of the cooling medium is 20℃-60℃.

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