Heat sink unit and two-phase flow high-efficiency heat dissipation system with three-dimensional space structure

Abstract

The application discloses a heat sink unit and a two-phase flow high-efficiency heat dissipation system with a three-dimensional space structure, and multiple groups of parallel micro-channel units are arranged in the heat sink unit; each group of the micro-channel units is composed of an inlet header, an inlet throttling structure, a main channel, a secondary channel, a micro-nozzle, a micro-cavity array and an outlet header; the main channel and the secondary channel are arranged between the inlet header and the outlet header, and the main channel and the secondary channel are arranged in parallel and alternately; the inlet throttling structure is arranged at the inlet of the main channel; the micro-cavity array is arranged on the side wall surface of the main channel, and the secondary channel is in fluid communication with the main channel through multiple micro-nozzles which are arranged at intervals along the length direction of the secondary channel. The application combines the main channel and the secondary channel with the jet flow of the micro-nozzle, strengthens boiling heat transfer and two-phase mixing, effectively inhibits boiling instability of the micro-channel, can be adapted to a three-dimensional array type heat source layout, and realizes high-efficiency and uniform heat dissipation of a high heat flux microwave assembly.

Description

Technical Field

[0001] This application relates to the field of high-efficiency heat dissipation technology for high-power electronic devices, and in particular to a two-phase flow high-efficiency heat dissipation system with a three-dimensional spatial structure. Background Technology

[0002] As high-power electronic devices rapidly evolve towards integration and higher power, the power density of individual heat-generating units (such as chips) continues to climb, increasing from 10W / cm² in the past. 2 Jump to 10 2 W / cm 2 Traditional air cooling and single-phase liquid cooling are no longer sufficient to meet heat dissipation requirements. Microchannel flow boiling, with its dual advantages of high specific surface area and phase change heat transfer, has become a core technology solution for high heat flux density heat dissipation. However, two-phase flow in microchannels is prone to flow instability problems such as flow oscillation, steam backflow, and localized burnout. Furthermore, the problem of uniform flow distribution for large-scale heat sources has not yet been properly solved.

[0003] To address the aforementioned heat dissipation challenges, existing technology (patent publication number: CN 116568001A) discloses a data center cooling device that utilizes thermosiphon and gravity coupling to achieve a self-driven circulation of the cooling medium, and incorporates a two-phase heat exchanger at the heat source end, comprising gradually expanding microchannels and interconnected microchannels. This solution reduces flow resistance and suppresses steam backflow through the gradually expanding structure, and balances the pressure and flow rate between the sub-channels using the interconnected channels, aiming to improve the heat transfer efficiency of the two-phase heat exchanger.

[0004] In recent years, high-power electronic devices have been rapidly developing towards high-density integration, three-dimensional stacking, and modularization. Three-dimensional array-type heat sources, such as server chip arrays, new energy vehicle power modules, and aerospace electronic components, have widely adopted modular designs. While modular design improves system flexibility and maintainability, it also places two core demands on cooling systems: First, the cooling system must be able to flexibly arrange heat sink structures in three-dimensional space to fit the three-dimensional stacking spatial layout of the modular heat source array; second, in a large-scale, multi-branch three-dimensional flow path, it is essential to achieve uniform distribution of the cooling fluid flow and effectively control pump power consumption to avoid flow imbalance and energy surges caused by complex flow paths. Under this trend, the existing technical solutions mentioned above have fundamental flaws and are no longer suitable for three-dimensional heat source scenarios. 1) Structural dimension mismatch: The microchannel heat exchanger is designed only for two-dimensional planar heat sources and cannot achieve spatial coupling with three-dimensional stacked and interlocked array heat sources; 2) Lack of three-dimensional flow distribution: The lack of multi-stage distribution / return channels makes it impossible to achieve uniform distribution of cooling fluid in a three-dimensional multi-branch, large-scale parallel heat sink array, which can easily lead to uneven heat dissipation and local overheating of each heat-generating unit in the three-dimensional space. 3) Insufficient high heat flux stabilization capability: Relying solely on the single method of gradual expansion and interactive channels to suppress boiling instability, without setting up multiple reinforcement structures such as inlet throttling, micro-nozzle jetting, and micro-cavity nucleation, it is still prone to flow oscillation and burn-out in three-dimensional high heat flux density scenarios.

[0005] In view of this, existing technologies cannot simultaneously meet the heat dissipation requirements of three-dimensional spatial adaptation, uniform flow distribution, and stable boiling under high heat flux density, making it difficult to adapt to efficient heat dissipation of three-dimensional array heat sources. Therefore, this application proposes a two-phase flow efficient heat dissipation system with a three-dimensional spatial structure to solve the aforementioned problems of existing technologies. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a heat sink unit and a two-phase flow high-efficiency heat dissipation system with a three-dimensional spatial structure that can effectively suppress steam backflow and promote steady-state nucleation boiling.

[0007] To solve the above-mentioned technical problems, this application provides the following technical solution: A heat sink unit includes multiple sets of parallel microchannel units. Each set of microchannel units comprises an inlet manifold, an inlet throttling structure, a main channel, a secondary channel, micro-nozzles, a micro-cavity array, and an outlet manifold. The main channel and the secondary channel are arranged between the inlet manifold and the outlet manifold, and are arranged in parallel and alternately. The inlet throttling structure is located at the inlet of the main channel. The micro-cavity array is provided on the wall of the main channel. The secondary channel is in fluid communication with the main channel through multiple micro-nozzles spaced apart along its length.

[0008] This application also provides a three-dimensional spatial structure for a two-phase flow high-efficiency heat dissipation system, comprising: An array composed of the aforementioned heat sink units; A cooling medium distribution and collection flow path system is provided, which is connected to the working medium inlet and working medium outlet of the heat sink unit array, respectively.

[0009] In some embodiments of this application, the cross-sectional area of ​​the inlet throttling structure is designed to be significantly smaller than the inlet cross-sectional area of ​​the downstream main and secondary channels. This structure, by reducing the volume of the channel inlet section and increasing the local pressure gradient of the inlet section, effectively prevents the reverse flow of high-temperature steam originating downstream towards the upstream (inlet header direction), thereby fundamentally suppressing the triggering of explosive boiling and flow oscillations. Simultaneously, the adiabatic pressure reduction effect generated by throttling allows the near-saturated liquid cooling medium to be in the gas-liquid two-phase region upon entering the expanding main and secondary channels, achieving spontaneous bubble nucleation (flash evaporation) without superheating, thus advancing and homogenizing the boiling initiation process.

[0010] In some embodiments of this application, the width of the secondary channel is typically smaller than that of the main channel. A regularly arranged array of microcavities is fabricated on the sidewall of the main channel. These microcavities, acting as stable vaporization nuclei, significantly reduce the initial superheat of boiling and promote the uniform and continuous generation of numerous tiny bubbles, thereby enhancing nucleate boiling heat transfer. Furthermore, the capillary force generated by the microcavity array helps maintain and transport a thin liquid film on the wall surface, enhancing surface wettability, which is crucial for delaying localized drying under high heat flux.

[0011] In some embodiments of this application, multiple micro-nozzles are opened at certain intervals along the length of the secondary channel, connecting the secondary channel to the adjacent main channel. The injection direction of the micro-nozzles is preferably at an angle of 50° to 70° to the mainstream direction of the working fluid in the main channel. This invention can stably form a positive pressure difference between the secondary channel and the main channel: First, the inlet throttling structure is only set at the inlet of the main channel, significantly increasing the flow resistance at the inlet section of the main channel, causing the inlet pressure of the main channel to drop rapidly, while the secondary channel has no equivalent throttling structure, thus actively constructing an initial pressure difference; Second, the width of the secondary channel is smaller than that of the main channel. According to Poiseuille's law, its flow resistance along the path is naturally higher than that of the main channel. Combined with the two-phase flow pressure reduction effect brought about by the core boiling in the main channel, the positive pressure difference between the secondary channel and the main channel can be further amplified and stably maintained. Driven by the pressure difference, the cooling medium from the secondary channel flows into the main channel as a high-speed microjet after passing through the micro-nozzle. The jet formation mechanism is based on the fluid dynamics continuity equation and Bernoulli's principle: the pressure difference between the secondary and main channels drives the working medium to flow into the main channel. When the working medium passes through the micro-nozzle with its rapidly shrinking cross-sectional area, the drastic reduction in flow area significantly increases the working medium velocity, ultimately forming a directional high-speed microjet. This design offers multiple benefits: 1) The jet strongly disturbs the thermal boundary layer near the wall of the main channel, greatly enhancing convective heat transfer; 2) The shearing and impact effects of the jet promote the breakup and elimination of large bubbles in the main channel, accelerating the renewal and mixing of the gas-liquid interface and improving the overall heat transfer coefficient; 3) The jet momentum can supplement the flow kinetic energy of the main channel, optimizing the flow distribution and pressure balance within the entire flow channel unit.

[0012] In some embodiments of this application, the hydraulic diameter design of the multi-stage distribution channels follows a progressively decreasing principle. The primary distribution channel connects to the system main pipe and is responsible for the primary distribution of the working fluid; the secondary distribution channel connects the primary distribution channel to multiple tertiary distribution channels; and the tertiary distribution channels are directly connected to the inlet of each heat sink unit. This is achieved by setting... D h2 = (0.7~0.8) × D h1 , D h3 = (0.7~0.8) × D h2It can meet the requirements of compact space layout while matching the flow resistance distribution of the flow channel system with the parallel resistance of each heat sink unit, thereby achieving a flow uniformity error of less than ±5% to all heat sink units with the lowest pump power consumption of the system.

[0013] In some embodiments of this application, the heat sink unit structure design takes into account lightweight, high strength and good manufacturability, which meets the stringent requirements of aerospace, automotive electronics and other scenarios for the weight and structural strength of the heat dissipation system.

[0014] In some embodiments of this application, the overall external contour of the heat sink unit is processed into a standard fractal tree shape, which is perfectly matched with the basic unit structure of the three-dimensional array heat source; multiple heat sink units can be seamlessly spliced ​​to form a cold plate array covering the entire three-dimensional array heat source, while providing solid mechanical support and a good thermal contact interface for the upper components, realizing the integration of heat dissipation function and structural support, and improving integration.

[0015] In some embodiments of this application, the working fluid inlet and outlet of the heat sink unit are located on the side and connected to the cooling circulation system through an external piping system; the inlet manifolds of multiple heat sink units can be connected to a centralized distribution manifold, and the outlet manifolds can be connected to a centralized collection manifold, which facilitates modular assembly and maintenance.

[0016] Compared with the prior art, this application has at least the following advantages: 1) This application constructs a highly controllable microscale boiling and flow environment through the synergistic design of "inlet throttling + main and secondary channels + micro-nozzle jet + wall microstructure"; inlet throttling blocks steam backflow, micro-cavities provide stable nucleation sites, micro-nozzle jet breaks up large bubbles and stabilizes the flow field, and the main and secondary channels work together to balance the flow rate. While significantly improving heat transfer performance, it effectively suppresses the inherent boiling instability of microchannels and ensures the smoothness and reliability of the heat dissipation process. 2) This application solves the problem of uniform flow and pressure distribution in large-scale parallel heat sink units by designing a multi-stage distribution channel with a specific hydraulic diameter decreasing relationship, thereby avoiding local overheating and improving the uniformity and reliability of heat dissipation of array-type heat sources. 3) The heat sink unit of this application adopts a fractal tree design integrated with the three-dimensional heat source array, realizing a high degree of unity between the heat dissipation functional unit and the heat source structural unit. The modular design facilitates expansion, maintenance and replacement, and improves the maintainability of the three-dimensional heat source array. 4) This application comprehensively adopts multiple passive heat transfer enhancement methods (micro-cavities, hydrophilic surfaces, micro-nozzle jets, and inlet throttling), all of which rely on the flow channel structure and surface modification to achieve the goal. It requires no external power and consumes no extra power. The multi-stage decreasing flow channel precisely matches the flow resistance to reduce system losses. It achieves ultra-high heat flux density and efficient cooling and heat dissipation without significantly increasing pump power consumption, making it suitable for energy-constrained scenarios such as aerospace. 5) This application has a clear structure, strong process feasibility, is easy to mass-produce in an engineered manner, and has high practical value and promotion prospects. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0018] Figure 1 This is a three-dimensional structural schematic diagram of a microchannel heat sink unit applied to an array-type heat source according to an embodiment of this application; Figure 2 This is a rear view of the microchannel heat sink unit array according to an embodiment of this application; Figure 3 This is a split view of the microchannel heat sink unit array according to an embodiment of this application; Figure 4 for Figure 3 Middle AA Top view of the cross-sectional structure of the line; Figure 5 for Figure 3 Middle AA A sectional view of the line structure from an oblique angle. Figure 6 This is a partial enlarged view of the inlet section of the microchannel heat sink unit in an embodiment of this application; Figure 7 This is a partially enlarged schematic diagram illustrating the principle of enhanced heat transfer through micro-cavity array on the main channel wall and micro-nozzle jet in some embodiments of this application. The reference numerals in the attached figures are explained as follows: 1-Heat sink unit, 2-Heat source, 3-Cooling medium main pipe inlet, 4-Cooling medium main pipe outlet, 5-Primary flow channel, 6-Secondary flow channel, 7-Tertiary flow channel; 8-Heat sink unit inlet, 9-Heat sink unit outlet; 10-Inlet manifold, 11-Outlet manifold, 12-Inlet throttling structure, 111-Main channel, 112-Secondary channel, 1121-Micro-cavity array, 1122-Micro-nozzle. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0020] refer to Figure 1 This illustrates a typical application scenario of the embodiments of this application (taking an airborne active phased array radar system as an example; this application is also applicable to other three-dimensional array heat source scenarios such as high-power servers and new energy vehicles). Multiple microchannel heat sink units 1 are tightly spliced ​​together to form a cold plate array that perfectly matches the shape of the three-dimensional heat source array surface; a high heat flux density heat source 2 is installed on the upper surface of each heat sink unit 1, and a thermally conductive interface material is laid between the two and they are tightly bonded, forming a three-dimensional array heat dissipation architecture with alternating layers of "heat source-cold plate", realizing efficient heat conduction between the heat source and the cold plate and tight structural integration.

[0021] refer to Figure 1 This illustrates the structure of the multi-stage distribution channel system of this application. The cooling medium (exemplarily R134a, but other media suitable for two-phase flow heat dissipation can also be selected) enters the multi-stage distribution channel system through the inlet manifold 3. This system adopts a tree-like branching structure, enabling precise, step-by-step distribution of the medium: firstly, it enters the primary channel 5 with the largest hydraulic diameter for initial distribution; then, it is diverted to several secondary channels 6 with the next smallest hydraulic diameter for secondary distribution; finally, it is transported to the inlet 8 of each heat sink unit through numerous tertiary channels 7 with the smallest hydraulic diameter. In this embodiment, the hydraulic diameters of the primary, secondary, and tertiary channels specifically meet the following requirements: D h2 = 0.75 D h1 , D h3 = 0.75 D h2 The proportional relationship (this ratio is an example value and can be adjusted according to the actual scenario within the range of 0.7~0.8); this design can make the flow channel resistance distribution and the parallel resistance of each heat sink unit precisely match within a limited installation space, ensuring that the working fluid is delivered to each parallel heat sink unit 1 with uniform pressure and flow, thus ensuring uniform heat dissipation of the large-scale array.

[0022] refer to Figure 2 and Figure 3The diagram details the internal structure of a single heat sink unit 1. Multiple sets of parallel microchannel units are arranged within the heat sink unit 1. The flow and heat exchange process of the cooling medium is as follows: the cooling medium enters the inlet header 10 from the side inlet of the heat sink unit. After uniform distribution of the medium through the inlet header 10, it flows into the core inlet throttling structure 12. The flow channel cross-section of this inlet throttling structure 12 contracts sharply, and its cross-sectional area is significantly smaller than the inlet cross-sectional area of ​​the downstream main channel 111 and secondary channel 112. This achieves the aforementioned technical effect of "suppressing steam backflow and promoting flash vaporization," fundamentally improving the stability of boiling heat dissipation.

[0023] The working fluid, after passing through the inlet throttling structure 12, enters the main channel 111 and the secondary channel 112 in parallel. To enhance nucleation boiling heat transfer and improve the stability of two-phase flow, this embodiment provides a micro-cavity array 1121 on the sidewall of the main channel 111 and arranges micro-nozzles 1122 that connect to the main channel along the length of the secondary channel 112.

[0024] The micro-cavity array 1121 is a micron-scale pit structure formed periodically on the inner wall of the main channel 111. As a stable vaporization core, it can reduce the initial superheat of boiling, promote the uniform and continuous generation of fine bubbles, and enhance nucleation boiling heat transfer from the source.

[0025] The micro-nozzle 1122 is a micro-scale injection channel that is spaced apart along the length of the secondary channel 112. It is used to connect the secondary channel 112 and the main channel 111. Its axis forms an angle of 50° to 70° (preferably 60°) with the mainstream direction of the working fluid in the main channel 111. The working fluid in the secondary channel 112 can be injected into the main channel 111 through the micro-nozzle 1122 to form a high-speed micro-jet. This accelerates the mixing and interface renewal of the gas-liquid two-phase flow by disturbing the thermal boundary layer and breaking up large bubbles. At the same time, it replenishes the flow kinetic energy and optimizes the flow distribution and pressure balance in the flow channel.

[0026] The secondary channel 112 is narrower than the main channel 111, and the sidewall of the main channel 111 is processed with a regularly arranged array of micro-cavities 1121. Micro-nozzles 1122 are spaced apart along the length of the secondary channel 112, which can realize the connection between the secondary channel 112 and the adjacent main channel 111. The jet effect can significantly improve the overall heat transfer coefficient and ensure the heat dissipation stability under high heat flux conditions.

[0027] After heat exchange, the working fluid merges at the ends of the main channel 111 and the secondary channel 112, enters the outlet header 11, and is discharged from the heat sink unit 1. The working fluid after heat exchange is collected through the outlet 9 of the heat sink unit to the tertiary flow channel 7, and then successively flows through the secondary flow channel 6 and the primary flow channel 5, and finally flows back to the cooling circulation system from the outlet manifold 4 to complete the entire heat dissipation cycle.

[0028] This application has a clear structure, strong process feasibility, and is easy to mass-produce in an engineered manner, possessing high practical value and promising prospects for promotion. Those skilled in the art will understand that the above embodiments are merely illustrative of the technical solutions of this application and do not constitute a limitation thereof; modifications, equivalent substitutions, and improvements made to the number of microchannel units, the specific shape and arrangement of microcavities, the angle of micronozzles, etc., without departing from the principles of this application, should all be included within the scope of protection of the claims of this application.

Claims

1. A heat sink unit, wherein multiple sets of parallel microchannel units are provided within the heat sink unit; characterized in that, Each microchannel unit comprises an inlet manifold, an inlet throttling structure, a main channel, a secondary channel, micro-nozzles, a micro-cavity array, and an outlet manifold. The main channel and the secondary channel are arranged between the inlet manifold and the outlet manifold, and the main channel and the secondary channel are arranged in parallel and alternately. The inlet throttling structure is located at the inlet of the main channel. The micro-cavity array is provided on the side wall of the main channel. The secondary channel is in fluid communication with the main channel through a plurality of micro-nozzles spaced apart along its length.

2. The heat sink unit according to claim 1, characterized in that, The inlet throttling structure is a vertical baffle plate located between the inlets of the main channel.

3. The heat sink unit according to claim 1, characterized in that, The micro-cavity array is a tiny pit structure formed periodically on the inner wall of the main channel. The size of the tiny pit structure is on the micrometer scale, which is used to enhance the nucleation sites of nucleation boiling.

4. The heat sink unit according to claim 1, characterized in that, The axial direction of the micro-nozzle forms an angle of 50° to 70° with the mainstream direction of the working fluid in the main channel.

5. The heat sink unit according to claim 1, characterized in that, The entire wall surface of both the main channel and the secondary channel is treated with micro- and nano-structures to form a hydrophilic micron- and nano-scale composite rough structure.

6. The system according to claim 1, characterized in that, The working fluid inlet and working fluid outlet of the heat sink unit are respectively located on the side of the heat sink unit.

7. A two-phase flow high-efficiency heat dissipation system with a three-dimensional spatial structure, characterized in that, include: An array comprising the heat sink unit as described in any one of claims 1-6; A cooling medium distribution and collection flow path system is provided, which is connected to the working medium inlet and working medium outlet of the heat sink unit array, respectively.

8. The two-phase flow high-efficiency heat dissipation system according to claim 7, characterized in that, The cooling medium distribution and collection flow path system includes a multi-stage distribution / return flow channel, which includes multiple flow channels connected sequentially along the flow direction of the cooling medium. The multi-stage flow channel is used to distribute the cooling medium from the primary flow channel to the final flow channel. The hydraulic diameter of the primary flow channel to the final flow channel decreases sequentially. The heat sink unit is connected to the final flow channel of the multi-stage distribution / return flow channel.

9. The two-phase flow high-efficiency heat dissipation system according to claim 8, characterized in that, The hydraulic diameters of the multi-stage flow channels satisfy the following relationship: D i+1 = (0.7~0.8) × D i in, D i , D i+1 These are the hydraulic diameters of the i-th and (i+1)-th flow channels, respectively.

10. The two-phase flow high-efficiency heat dissipation system according to claim 8, characterized in that, Multiple heat sink units can be spliced ​​and combined to form a heat sink unit array that matches a high-power three-dimensional array heat source. The heat sink unit array and the corresponding heat source array are arranged in a three-dimensional stacked structure with the elements interlocked.

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