A two-phase immersion liquid cooling system

Abstract

The application discloses a two-phase immersion liquid cooling system, comprising a liquid cooling cabinet, an external heat exchanger, a circulating pump and a cooling tower. The liquid cooling cabinet comprises a sealed cabinet, a high-performance server, a porous jet module and an immersion cooling liquid. The high-performance server is immersed in the immersion cooling liquid. The surface of the arrayed high-heat-flow chip is provided with a composite phase change radiator. A bubble flow guide plate is arranged between adjacent upstream and downstream chips. The porous jet module introduces low-temperature immersion cooling liquid from the sealed cabinet inlet through a bypass liquid supply pipe and has a temperature self-adaptive flow adjusting function. During system operation, the composite phase change radiator strengthens local boiling heat exchange of the chip, the bubble flow guide plate regulates and controls the migration path of upstream bubbles, and the porous jet module directionally supplies liquid to the high-heat-flow area, thereby enhancing the heat exchange effect of the composite phase change radiator. The application relieves the problems of large-scale inter-chip thermal cascade, bubble retention and local heat transfer deterioration, and improves the system heat dissipation capacity, temperature uniformity and operation stability.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology for high-performance GPU servers, specifically relating to an adaptive enhanced two-phase immersion liquid cooling system that integrates local hot spot boiling enhancement, thermal cascade effect suppression, and self-driven jet regulation technology. Background Technology

[0002] With the rapid development of emerging information technologies such as big data, cloud computing, artificial intelligence, and next-generation communication technologies, data centers, as important carriers of computing infrastructure, are undertaking increasingly demanding data processing and storage tasks. To meet the continuously growing computing power requirements, server equipment is evolving towards higher integration, higher power density, and higher load capacity. The heat generation power of chips and other electronic components is constantly increasing, and the local heat flux density is significantly increasing, thus placing higher demands on data center thermal management technologies.

[0003] In recent years, with the continuous increase in server power, data center cooling methods have gradually evolved from traditional air cooling to liquid cooling technology. Currently, mainstream liquid cooling technologies include three categories: cold plate, spray, and immersion. Among them, immersion liquid cooling has become the most promising thermal management method for high-performance servers due to its higher heat exchange efficiency and system integration, as well as its ability to meet the energy consumption reduction needs of data centers. Based on whether the coolant undergoes a phase change during heat exchange, immersion liquid cooling technology can be divided into single-phase immersion liquid cooling and two-phase immersion liquid cooling. With the surge in power of major components such as CPUs and GPUs in high-performance servers, if single-phase immersion liquid cooling technology is used, under the conditions of limited device temperature rise and heat exchange structure, only increasing the coolant flow rate can meet the heat dissipation demand, leading to increased energy consumption in the data center. In contrast, two-phase immersion liquid cooling utilizes the latent heat of the coolant phase change to remove server heat, achieving a larger heat exchange capacity with a smaller circulation flow rate, thereby reducing pump power consumption and pipeline flow resistance, and thus having better application prospects in high-performance server heat dissipation.

[0004] Currently, most two-phase immersion liquid cooling systems focus on enhancing boiling heat transfer in localized high heat flux chips. Methods such as designing porous capillary structures on the substrate surface and applying hydrophilic / hydrophobic liquid surface treatments are used to enhance local boiling heat transfer. It should be noted that these are all passive enhancement methods. When the heat flux density further increases or bubbles continue to accumulate in localized areas, localized drying problems may still occur. Furthermore, high-performance servers typically employ an array of multiple high heat flux chips, which is prone to thermal cascading: on the one hand, bubbles from upstream can accumulate in downstream areas, forming drying zones; on the other hand, the liquid temperature at the downstream chip inlet does not increase significantly, thus weakening the heat transfer potential.

[0005] Therefore, it is necessary to actively and directionally replenish the high heat flux region of the immersion liquid cooling system, and at the same time combine it with local enhanced boiling heat transfer, so as to mitigate the adverse effects of the temperature difference and bubble behavior difference of the coolant near the chip in different locations on the heat transfer performance. Summary of the Invention

[0006] The technical problem to be solved by this invention is to propose a two-phase immersion liquid cooling system that reduces the adverse effects of local bubble accumulation and uneven coolant temperature on the heat exchange performance of high-performance servers, improves local boiling heat exchange capacity, and enhances the temperature uniformity and operational stability of high-performance servers.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows: A two-phase immersion liquid cooling system includes a liquid cooling cabinet comprising a sealed enclosure, a high-performance server, a composite phase change heat sink, and an immersion coolant. The high-performance server is completely immersed in the immersion coolant. The composite phase change heat sink includes a heat sink base and a gas-liquid separation structure. High heat flux chips of the high-performance server are arranged on the heat sink base, and the heat sink base and the gas-liquid separation structure are spaced apart and form a jet channel. The gas-liquid separation structure is composed of an array of heat exchange units, each heat exchange unit including an exhaust channel and a liquid return channel. The exhaust channel is used to discharge bubbles generated by boiling on the surface of the heat sink base, so that each heat exchange unit forms a local exhaust zone and a local liquid return zone. The liquid return channel is used to replenish the liquid coolant to the surface of the heat sink base. The liquid-cooled cabinet also includes a multi-hole jet module, which consists of a cavity and a distributor. The cavity is located on the outer periphery of the composite phase change heat sink. The cavity includes an exhaust port on the top surface, a jet channel inlet on two opposite sides, and a jet channel outlet. The distributor has a jet hole that communicates with the jet channel inlet. The jet channel inlet communicates with the jet channel of the composite phase change heat sink. The coolant sprayed through the jet hole of the distributor flows through the jet channel across the surface of the heat sink base to replenish the coolant.

[0008] The present invention provides an adaptive enhanced two-phase immersion liquid cooling system. When the system is working, the composite phase change heat sink is used to enhance local boiling heat transfer on the chip surface and promote gas-liquid separation. The bubble guide plate is used to regulate the migration path of bubbles generated by the upstream chip to reduce the thermal cascading effect caused by the accumulation of bubbles near the downstream chip. The porous jet module sprays the liquid directionally onto the surface of the composite phase change heat sink to achieve active liquid replenishment.

[0009] Furthermore, the composite phase change heat sink is mounted on the surface of a high heat flux chip and consists of a heat sink base and a gas-liquid separation structure, making it particularly suitable for surfaces with a surface area >50cm². 2A large-area, high-heat-flux chip is constructed. The heat sink substrate is made of a diamond / copper composite material with high thermal conductivity, which improves the overall thermal conductivity of the substrate. One side of the heat sink substrate is tightly attached to the surface of the high-heat-flux chip, while the other side has microribs arranged on its surface. Simultaneously, the surface of the microribs is treated to form a micro / nano-scale porous structure, including but not limited to methods such as spraying graphene oxide coating, sintering porous coatings, and electrochemical deposition. The porous structure increases surface roughness and enhances local boiling heat transfer.

[0010] Furthermore, a gas-liquid separation structure is positioned above the heat sink base and closely attached to the top of the micro-ribs. This structure is arranged in a grid pattern on the surface of the heat sink base, dividing the composite phase change radiator into multiple adjacent heat exchange units. Each heat exchange unit includes an exhaust channel and a liquid return channel, creating a local exhaust zone and a local liquid return zone. The exhaust channel is located in the central region of the heat exchange unit and includes multiple vertical deep-hole channels. The pore diameter is designed based on the bubble detachment diameter during nucleation boiling and the bubble diameter near the critical heat flux density. The interior of the vertical deep-hole channels undergoes a wettability gradient modification treatment, gradually increasing the wetting angle of the inner wall with the submerged coolant from the end closest to the heat sink base to the end furthest away, driving bubbles generated on the base surface to leave the surface. To reduce the vapor flow resistance of the exhaust channel, the porosity of the local exhaust zone is not less than 90%.

[0011] Furthermore, the liquid return channel is located in the circumferential region of the heat exchange unit and adopts a fractal flow channel structure, including a main flow channel, a primary branch flow channel, and a terminal capillary flow channel. The flow area of ​​the main flow channel is larger than that of the primary branch flow channel, and the flow area of ​​the primary branch flow channel is larger than that of the terminal capillary flow channel. The terminal capillary flow channel is used to generate capillary liquid suction, thereby enabling the liquid coolant to be replenished to the bottom of the radiator. At the same time, the small characteristic size of the terminal capillary flow channel can suppress a large number of air bubbles from entering the return channel.

[0012] Furthermore, a bubble guide plate is disposed between the upstream and downstream chips. The bubble guide plate is inclined relative to the normal direction of the surface of the high-performance server, with an inclination angle of about 10-30°. The upper end is offset away from the downstream high heat flux chip relative to the lower end. The height of the upper end of the bubble guide plate needs to be about 10-20 mm higher than the upper edge of the tallest device on the high-performance server. The bubble guide plate is provided with multiple millimeter-scale through holes. The diameter of the through holes is about 0.5-1 mm, and the porosity is not less than 90%. When the large-sized bubbles generated and rising from the upstream chip pass through the millimeter-scale through holes, they are restricted and sheared by the through hole boundary and divided into multiple small-sized bubbles.

[0013] Furthermore, the porous jet module consists of a cavity and a distributor. The cavity of the porous jet module is located on the outer periphery of the composite phase change heat sink. A preset distance is maintained between the inner wall of the cavity and the outer surface of the composite phase change heat sink. An exhaust hole is opened on the top of the cavity corresponding to the exhaust channel of the heat exchange unit. A preset gap between the gas-liquid separation structure of the composite phase change heat sink and the heat sink base serves as the jet channel. The distributor is located outside the cavity, and the distributors in the cabinet are interconnected. Finally, they are connected to the main circulation pipeline through the bypass liquid supply pipe. The distributor is provided with jet holes, which are aligned with the jet channel. The jet sprays from bottom to top onto the heat sink base to replenish the surface coolant. A flow adaptive valve is installed on the back of the cavity. The flow adaptive valve is made of shape memory material, including but not limited to nickel-titanium-based shape memory alloys and copper-based shape memory alloys, with a thickness of 0.1-0.5 mm. It can undergo large bending deformation under small temperature changes. After pre-training, the flow adaptive valve plate remains upright at room temperature. When the temperature of the submerged coolant near the flow adaptive valve plate approaches the derating temperature, it undergoes bending deformation, and the opening at the outlet increases.

[0014] Furthermore, the immersion coolant is an insulating cooling medium with a boiling point at standard atmospheric pressure not exceeding the derating temperature of the high heat flux chip, and includes at least one of hydrofluoroolefins, perfluoroolefins, perfluoroalkanes, and mixtures thereof.

[0015] The beneficial effects of this invention are as follows: 1. The present invention proposes a two-phase immersion liquid cooling system, which achieves the synergistic effect of bubble migration path control, local boiling heat transfer enhancement, and low-temperature immersion coolant directional replenishment by setting a composite phase change heat sink on the surface of high heat flux chips in high-performance servers, setting a bubble guide plate between upstream and downstream chips, and arranging a porous jet module with temperature adaptive flow regulation function. This alleviates problems such as thermal cascading of chips in different locations, bubble aggregation and retention, and local heat transfer deterioration in high-performance servers, and improves the overall heat dissipation capacity, temperature uniformity, and operational stability of high-performance servers.

[0016] 2. The composite phase change heat sink utilizes the local boiling enhancement treatment on the surface of the heat sink base and the grid-like partitioned gas-liquid separation structure to decouple the bubble separation path and the coolant return path. It is especially suitable for large-scale high heat flux chips, avoids the formation of a high thermal resistance gas film on the heat exchange surface, and improves the heat dissipation stability of the system under high load conditions.

[0017] 3. The bubble guide plate helps reduce the impact of bubbles generated by upstream chips on downstream chips, prevents bubbles from accumulating in the downstream area, and alleviates the thermal cascading effect.

[0018] 4. The multi-hole jet module actively directs the low-temperature coolant from the cabinet inlet into the high heat flux area, enhancing the local replenishment capacity. It can also automatically adjust the jet flow rate ratio according to temperature changes, thereby improving the system adaptability under variable temperature conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the two-phase adaptive enhanced immersion liquid cooling system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the composite phase change heat sink structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the heat exchange unit structure according to an embodiment of the invention; Figure 4 This is a schematic diagram of the liquid reflux channel. Figure 5 This is a schematic diagram of the bubble guide plate structure according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the porous jet module according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the assembly of the porous jet module and the composite phase change heat sink according to an embodiment of the present invention; Figure 8 Schematic diagram of the installation structure for surface-enhanced heat exchange components in high-performance servers; The components are as follows: 1-Sealed cabinet; 2-High-performance server; 3-Bubble guide plate; 4-Composite phase change heat sink; 5-Porous jet module; 6-Bypass liquid supply pipe; 7-Immersion coolant liquid flow direction; 8-Immersion coolant vapor flow direction; 9-External heat exchanger; 10-Cooling water flow direction; 11-Circulating pump; 12-Cooling tower; 13-High heat flux chip; 14-Heat sink base; 15-Micro ribs; 16-Gas-liquid separation structure; 17-Heat exchange unit; 18-Exhaust channel; 19-Liquid return channel; 20-Jet orifice; 21-Diverter; 22-Cavity; 23-Flow adaptive valve; 24-Exhaust port; 25-Jet direction; 26-Main flow channel; 27-First-level branch flow channel; 28-Terminal capillary flow channel. Figure 3 In the schematic diagram of the heat exchange unit structure, the micro-ribbed columns are not labeled. Detailed Implementation

[0020] To enhance understanding of the present invention, we will now describe it in further detail with reference to the accompanying drawings. These embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0021] Figure 1A specific embodiment of an adaptive enhanced immersion liquid cooling system is shown, including: a sealed cabinet 1, a high-performance server 2, a bubble guide plate 3, a composite phase change radiator 4, a porous jet module 5, a bypass supply pipe 6, a liquid flow direction of the immersion coolant 7, a vapor flow direction of the immersion coolant 8, an external heat exchanger 9, a cooling water flow direction 10, a circulating pump 11, and a cooling tower 12. The high-performance server 2 is arranged in the sealed cabinet 1, and the gaps in the sealed cabinet 1 are filled with immersion coolant. The height of the immersion coolant is not less than the height of the high-performance server 2, but a certain gap is left at the top of the sealed cabinet 1. A composite phase change heat sink 4 is arranged on the high heat flux chip 13 of the high-performance server 2. A porous jet module 5 is arranged outside the composite phase change heat sink 4. A bubble guide plate 3 is arranged between the upper and lower chips. The primary side of the external heat exchanger 9 is connected to the circulating pump 11 and the cooling tower 12 through pipelines to form a cooling water circulation. The secondary side is connected to the inlet and outlet of the sealed cabinet 1 through pipelines. The sealed cabinet 1 is equipped with a bypass liquid supply pipe 6 to form an immersion coolant circulation.

[0022] Figure 2 , 3 This is a schematic diagram of the composite phase change heat sink 4, including a high heat flux chip 13, a heat sink base 14, micro ribs 15, an exhaust channel 18, and a liquid return channel 19, as shown. Figure 2 As shown, the composite phase change heat sink includes a heat sink base 14 and a gas-liquid separation structure 16. One side of the heat sink base 14 is tightly attached to the surface of the high heat flux chip 13, while the other side has micro-ribs 15 arranged on its surface. The micro-ribs 15 are treated to form a micro / nano-scale porous structure, including but not limited to spraying a graphene oxide coating, sintering a porous coating, and electrochemical deposition. The height of the micro-ribs 15 is 0.5-2 mm, and the spacing between adjacent micro-ribs 15 is 0.5-2 mm. Immersion coolant forms a liquid film on the surface of the heat sink base 14 under capillary action. In this embodiment, the top of the composite phase change heat sink 4 is the gas-liquid separation structure 16. The gas-liquid separation structure 16 and the heat sink base 14 are arranged in a mesh-like partition on their surfaces, dividing the composite phase change heat sink 4 into multiple adjacent heat exchange units 17. Figure 3As shown, the heat exchange unit 17 includes an exhaust channel 18 and a liquid return channel 19, forming a local exhaust zone and a local liquid return zone in each heat exchange unit 17. The exhaust channel 18 is located in the central region of the heat exchange unit 17 and includes multiple vertical deep-hole channels. The pore diameter is designed based on the bubble departure diameter during nucleate boiling and the bubble diameter near the critical heat flux density, varying from 0.5 to 5 mm. Bubbles generated during boiling on the surface of the heat sink 14 exit through the exhaust channel 18. The interior of the exhaust channel 18 undergoes a wettability gradient modification treatment, with the wetting angle of the inner wall to the submerged coolant ranging from 20°-60° near the heat sink 14 to 90°-130° away from the heat sink 14. This causes bubbles entering the vertical deep-hole channels to form an asymmetric gas-liquid interface curvature on the channel surface, and the resulting Laplace pressure difference drives the bubbles generated on the surface of the heat sink 14 to leave the surface. To reduce the bubble flow resistance of the exhaust channel 18, the porosity of the local exhaust zone is not less than 90%.

[0023] Figure 4 This is a schematic diagram of the liquid return channel 19. The liquid return channel 19 is located in the circumferential region of the heat exchange unit 17 and adopts a fractal flow channel structure, including a main flow channel 26, primary branch flow channels 27, and terminal capillary flow channels 28. The flow area of ​​the main flow channel 26 is larger than that of the primary branch flow channel 27, and the flow area of ​​the primary branch flow channel 27 is larger than that of the terminal capillary flow channel 28. The terminal capillary flow channel 28 is used to generate capillary suction, thereby replenishing the liquid coolant to the bottom of the radiator. Simultaneously, the smaller characteristic size of the terminal capillary flow channel 28 can suppress a large number of air bubbles from entering the liquid return channel 19. Furthermore, the flow area of ​​a single primary branch flow channel 27 should be 30%-60% of the flow area of ​​a single primary flow channel 26, and the flow area of ​​a single terminal capillary flow channel 28 should be 10%-30% of the flow area of ​​a single primary branch flow channel 27.

[0024] Figure 5 This is a schematic diagram of the bubble guide plate 3. The bubble guide plate 3 is positioned between the upstream and downstream chips. It is inclined relative to the surface normal of the high-performance server 2 at an angle of approximately 10-30° to reduce flow resistance and prevent localized bubble stagnation caused by an excessively large inclination angle. The upper end of the bubble guide plate 3 is offset away from the downstream chip relative to its lower end, allowing small bubbles to deviate from the downstream chip after passing through. The height of the upper end of the bubble guide plate 3 must be approximately 10-20 mm higher than the upper edge of the tallest device on the high-performance server 2. Figure 4 As shown, the bubble guide plate 3 is provided with through holes with a diameter of about 0.5-1 mm and a porosity of not less than 90%. Large bubbles generated and rising from the upstream chip are restricted and sheared by the through hole boundary, and are divided into multiple small bubbles, which reduces the coverage and retention of bubbles near the surface of the downstream high heat flux chip 13.

[0025] Figure 6 This is a schematic diagram of the multi-hole jet module 5, including a cavity 22 and a flow divider 21. The cavity 22 is a cap-shaped structure with an open lower surface. An exhaust port 24 is provided on the upper surface of the cavity 22. A jet inlet and a jet outlet are respectively provided on a pair of sides of the cavity 22. A flow adaptive valve 23 is installed at the jet outlet. The flow adaptive valve 23 is made of shape memory material, including but not limited to nickel-titanium-based shape memory alloys and copper-based shape memory alloys, with a thickness of 0.1-0.5 mm, capable of large bending deformation under small temperature changes. The flow divider 21 is located outside the cavity 22. The flow dividers 21 in the cabinet are interconnected and finally connected to the main circulation pipeline through a bypass supply pipe 6. A jet hole 20 is provided on the flow divider 21, and the jet hole 20 is connected to the jet inlet of the cavity 22.

[0026] Figure 7 This is a schematic diagram of the assembly of the porous jet module and the composite phase change heat sink. The composite phase change heat sink 4 is disposed inside the cavity 22 of the porous jet module 5. A preset distance is maintained between the inner wall of the cavity 22 and the outer surface of the composite phase change heat sink 4. The exhaust port 24 on the upper surface of the cavity 22 corresponds to the position of the exhaust channel 18 of the heat exchange unit. A preset gap between the gas-liquid separation structure 16 of the composite phase change heat sink 4 and the heat sink base 14 serves as the jet channel. The inlet of the jet channel is connected to the jet channel inside the composite phase change heat sink 4. When the bubbles generated by the composite phase change heat sink 4 leave the surface, they will eventually leave the cavity 22 through the exhaust port 24 after passing through the exhaust channel 18. The porous jet module sprays low-temperature immersion coolant into the jet channel inside the composite phase change heat sink 4 from bottom to top through the jet holes 20, replenishing the immersion coolant on the surface of the heat sink base 14. After pre-training, the flow adaptive valve plate 23 remains upright at room temperature. When the temperature of the submerged coolant near the flow adaptive valve plate 23 approaches the derating temperature, the flow adaptive valve plate 23 undergoes bending deformation, and the opening at the jet channel outlet increases, thereby increasing the jet flow rate of the submerged coolant at the jet hole 20 and enhancing the heat exchange effect of the composite phase change radiator 4.

[0027] Figure 8 This is a schematic diagram of the installation structure of the surface-enhanced heat exchange component for a high-performance server. The surfaces of multiple high-heat-flux chips 13 on the surface of the high-performance server 2 are tightly attached to the composite phase change heat sink 4. The cavity 22 of the porous jet module 5 is located on the outer periphery of the composite phase change heat sink 4. The inner wall of the cavity 22 maintains a preset distance from the outer surface of the composite phase change heat sink 4. The top of the cavity 22 has exhaust holes 24 corresponding to the exhaust channel 18 of the heat exchange unit and the liquid return channel 19. The bubble guide plate 3 is located between the upstream and downstream chips and is inclined relative to the normal direction of the surface of the high-performance server 2, with an inclination angle of about 10-30°.

[0028] The above specific embodiments are only for illustrating the technical concept and structural features of the present invention, and are intended to enable those skilled in the art to implement them. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and essence of the present invention should fall within the scope of protection of the present invention.

Claims

1. A two-phase immersion liquid cooling system, comprising a liquid cooling cabinet, the liquid cooling cabinet including a sealed cabinet (1), a high-performance server (2), a composite phase change heat sink (4), and an immersion coolant, wherein the high-performance server (2) is completely immersed in the immersion coolant; characterized in that, The composite phase change heat sink (4) includes a heat sink base (14) and a gas-liquid separation structure (16). The high heat flux chip (13) of the high-performance server (2) is arranged on the heat sink base (14). The heat sink base (14) and the gas-liquid separation structure (16) are spaced apart and form a jet channel. The gas-liquid separation structure (16) is composed of an array of heat exchange units (17). The heat exchange unit (17) includes an exhaust channel (18) and a liquid return channel (19). The exhaust channel (18) is used to discharge the bubbles generated by boiling on the surface of the heat sink base (14) through the exhaust channel (18), so that each heat exchange unit (17) forms a local exhaust area and a local liquid return area respectively. The liquid return channel (19) is used to replenish the liquid coolant to the surface of the heat sink base (14). The liquid-cooled cabinet also includes a multi-hole jet module (5), which consists of a cavity (22) and a distributor (21). The cavity (22) is located on the outer periphery of the composite phase change heat sink (4). The cavity (22) includes an exhaust hole on the top surface, a jet channel inlet on two opposite sides, and a jet channel outlet. The distributor (21) is provided with a jet hole that communicates with the jet channel inlet. The jet channel inlet communicates with the jet channel of the composite phase change heat sink (4). The coolant sprayed through the jet hole of the distributor (21) flows through the jet channel and passes over the surface of the heat sink base (14) to replenish the coolant.

2. The two-phase immersion liquid cooling system according to claim 1, characterized in that, The exhaust channel (18) is located in the central area of ​​the heat exchange unit (17) and includes multiple vertical deep hole channels with a diameter of 0.5-5 mm. The porosity of the local exhaust zone is not less than 90%. The inner wall of the exhaust channel (18) is treated with a wettability gradient modification so that the wetting angle of the inner wall to the submerged coolant increases vertically from bottom to top, driving bubbles of different sizes to detach from the surface of the heat sink base (14). The liquid return channel (19) is located in the circumferential area of ​​the heat exchange unit (17) and adopts a fractal flow channel structure, including a main flow channel, a first-level branch flow channel and a terminal capillary flow channel. The flow area of ​​the main flow channel is larger than that of the first-level branch flow channel, and the flow area of ​​the first-level branch flow channel is larger than that of the terminal capillary flow channel. The terminal capillary flow channel is used to generate capillary liquid absorption so that the submerged coolant liquid can flow back to the surface of the heat sink base (14) in a timely manner to replenish it.

3. The two-phase immersion liquid cooling system according to claim 1, characterized in that, A flow adaptive valve (23) is provided at the outlet of the jet channel; the flow adaptive valve (23) is made of shape memory material. When the temperature of the immersion coolant near the high heat flux chip (13) approaches the derating temperature, the shape memory alloy valve undergoes bending deformation, and the opening at the outlet increases, thereby increasing the jet flow rate of the immersion coolant at the jet hole (20) and enhancing the heat exchange effect of the composite phase change radiator (4).

4. The two-phase immersion liquid cooling system according to claim 2, characterized in that, Microribs (15) are provided in the jet channel between the heat sink base (14) and the gas-liquid separation structure (16); the surface of the microribs (15) is treated to form a micro-nano scale porous structure, which increases the surface roughness and enhances local boiling heat transfer.

5. The two-phase immersion liquid cooling system according to claim 1, characterized in that, A bubble guide plate (3) is provided between the upstream and downstream composite phase change heat sinks (4). The bubble guide plate (3) is used to regulate the migration path of bubbles generated by the upstream chip, so as to reduce the thermal cascading effect caused by the accumulation of bubbles near the downstream chip.

6. The two-phase immersion liquid cooling system according to claim 5, characterized in that, The bubble guide plate (3) is inclined relative to the surface normal direction of the high-performance server (2) at an angle of about 10-30°. The upper end is offset away from the downstream high heat flux chip (13) relative to the lower end, thereby changing the migration direction of the small-sized bubbles and causing them to deviate from the downstream high heat flux chip (13). The bubble guide plate (3) is provided with multiple millimeter-scale through holes. The large-sized bubbles generated and rising from the upstream high heat flux chip (13) are divided into multiple small-sized bubbles when passing through the millimeter-scale through holes.

7. The two-phase immersion liquid cooling system according to claim 6, characterized in that, The height of the upper end of the bubble guide plate (3) is about 10-20 mm higher than the upper edge of the highest height device on the high-performance server (2).

8. The two-phase immersion liquid cooling system according to claim 1, characterized in that, The immersion coolant is an insulating cooling medium with a boiling point at standard atmospheric pressure that does not exceed the derating temperature of the chip.

9. The two-phase immersion liquid cooling system according to claim 8, characterized in that, The immersion coolant is at least one of hydrofluoroolefins, perfluoroolefins, perfluoroalkanes, and mixtures thereof.

10. The two-phase immersion liquid cooling system according to any one of claims 1-9, characterized in that, It also includes an external heat exchanger (9), a circulating pump (11) and a cooling tower (12); the primary side of the external heat exchanger (9) is connected to the circulating pump (11) and the cooling tower (12) through a pipeline to form a cooling water circulation; the secondary side of the external heat exchanger (9) is connected to the inlet and outlet of the sealed cabinet through a pipeline to form an immersion coolant circulation.

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