Efficient passive heat dissipation system based on particle movement

Abstract

The invention discloses an efficient passive heat dissipation system based on particle movement, and belongs to the field of enhanced boiling heat dissipation. Movable particles are arranged at the bottom of the boiling pool, boiling heat transfer is promoted, and flow field disturbance and boiling are enhanced through particle movement; the kinetic energy of the phase change steam is used for pushing working medium circulation to realize passive heat dissipation; the microparticles comprise hydrophilic porous structures, a liquid-containing wetting state is kept in the boiling phase change heat transfer process, and the adhesion migration effect on a phase change interface in the boiling process is ensured; movable particles are used for providing a vaporization core for a heat source point boiling area in the boiling pool, heat is brought into a fluid area, and therefore boiling heat transfer is enhanced; the movement of the particles can cause disturbance of fluid in the boiling pool, the falling particles destroy large bubbles and steam films on the heating surface, bubble separation is accelerated, formation of the steam films is delayed, meanwhile, the temperature of a fluid area is increased, and the effect of continuous boiling of the fluid area is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of enhanced boiling heat dissipation, and more specifically to a high-efficiency passive heat dissipation system based on particle movement. Background Art

[0002] As the integration of electronic chips soars and the power density surges, heat dissipation has become a "bottleneck" problem. Conventional air-cooled heat dissipation has become increasingly ineffective and can hardly meet the temperature control requirements of chips for long-term stable operation. The boiling pool miniaturized heat dissipation solution came into being. A micro-scale boiling pool structure is constructed inside the chip packaging layer or the radiator. The working fluid boils and vaporizes in a tiny cavity under the action of the chip heat source, absorbing a large amount of heat, and then turns back into liquid and refluxes in the condensation section, forming an efficient heat dissipation closed loop. This solution has low heat dissipation thermal resistance and high heat transfer coefficient. It can firmly control the operating temperature of the chip within a safe range, ensuring the continuous and reliable operation of electronic equipment such as 5G base stations, high-performance computers, and artificial intelligence servers, and injecting "cool" power into the development of cutting-edge science and technology in the digital age.

[0003] Currently, research shows that porous structures greatly increase the effective surface area for heat transfer. The intricate interior and crisscrossing pores can provide a considerable number of tiny surfaces per unit volume compared to smooth surfaces. When liquid boils in a porous structure, bubbles are generated on the walls of these rich pores. The numerous pores are like tiny "boiling sites", allowing the vaporization process to unfold synchronously over a larger area. Therefore, how to use porous structures to effectively enhance the boiling heat transfer process has become a hot research topic in the industry.

[0004] There are related patent schemes for the existing structure to enhance the heat dissipation effect. For example, the patent publication number is CN110842202A, the publication date is February 28, 2020, and the name of the invention is: a free particle / porous medium composite enhanced boiling structure and its preparation method. The application has a number of cavities distributed in the porous matrix structure, and the cavities are dispersed with free particles that can move. The application is based on the enhanced characteristics of nucleation point activation and liquid supply to the nucleation site during boiling heat transfer, so as to prevent bubble merging and reduce liquid reflux resistance; at the same time, the collision of free particles in the boiling process is used to enhance the heat conduction, microlayer evaporation and convection heat transfer in the working fluid, so that bubbles are easy to nucleate, grow fast, and have a high detachment frequency, thereby achieving enhanced boiling heat transfer. However, this design cannot solve the problem of film boiling under high heat flow. The film boiling forms an evaporation zone on the heating surface, which will significantly reduce the effect of boiling heat transfer. Summary of the invention

[0005] 1. Technical problem to be solved by the invention

[0006] The purpose of the present invention is to overcome the problem that film boiling is easily occurred in the process of enhancing heat dissipation using porous particle structures in the prior art, and to provide an efficient passive heat dissipation system based on particle movement, which can effectively enhance the boiling heat transfer effect.

[0007] 2. Technical solution

[0008] In order to achieve the above object, the technical solution provided by the present invention is:

[0009] A high-efficiency passive heat dissipation system based on particle movement includes a boiling pool, a pipeline and a condenser. The boiling pool is filled with a fluid medium, and the bottom wall of the boiling pool has a heat-conducting layer for transferring heat from a heat source, and the heat-conducting layer is used to transfer the heat from the heat source to the boiling pool; movable particles are laid in the boiling pool; the inlet and outlet of the pipeline are respectively connected to the inner cavity of the boiling pool, and a condenser is provided on the outside of the pipeline.

[0010] Furthermore, the surface of the movable particle has a hydrophilic porous liquid storage structure.

[0011] Furthermore, the movable particle includes a microparticle skeleton and a plurality of microparticle pores formed on the surface of the microparticle skeleton.

[0012] Furthermore, a microparticle hollow portion is formed in the middle of the microparticle skeleton of the movable particle, and the microparticle porous surface is connected to the microparticle hollow portion in the center.

[0013] Furthermore, the movable particles are metal microparticles, and the thermal conductivity of the metal microparticles is not less than 20 W / (m·K).

[0014] Furthermore, a partition net is provided on the bottom wall of the boiling pool, and the partition net evenly divides the bottom of the boiling pool into a plurality of placement areas, and the movable particles are laid in each placement area respectively.

[0015] Furthermore, particle barrier nets are provided on the boiling pool at the inlet and outlet of the pipeline, respectively, and the particle barrier nets can restrict movable particles in the boiling pool from entering the interior of the pipeline.

[0016] Furthermore, the particle size of the movable particles is 5 to 250 μm.

[0017] Furthermore, the thermal conductivity of the heat-conducting layer is not less than 100 W / (m·K).

[0018] Furthermore, the liquid level of the fluid medium in the boiling pool is lower than the height of the inner cavity of the boiling pool, and the inlet and outlet positions of the pipeline communicating with the boiling pool are both below the liquid level of the fluid medium.

[0019] The present invention arranges movable particles at the bottom of the boiling pool to promote and enhance heat transfer during the formation and development of boiling heat transfer, and at the same time uses the movement of particles to enhance flow field disturbance and enhance boiling; the system uses the kinetic energy of phase change steam to promote the circulation of working fluid inside the system to achieve the effect of passive heat dissipation, the microparticles contain a hydrophilic porous structure, and maintain a liquid-containing wet state during the boiling phase change heat transfer process, ensuring the attachment and migration of the phase change interface during the boiling process; the movable particles are used to provide a vaporization core for the boiling zone of the heat source point in the boiling pool, and bring heat into the flow The particles can move in the boiling pool and carry the liquid to the heating surface for boiling again. When the particles hit the large bubbles, they will accelerate the detachment of the large bubbles. Under high heat flow, the falling of the porous particles will also destroy the steam film formed on the heating surface, and the carried liquid will boil again on the heating surface, which will alleviate the local hot spot problem caused by the evaporation zone, accelerate the detachment of bubbles and delay the formation of the steam film. At the same time, due to the arrangement of movable particles, the temperature of the fluid zone is increased, and the effect of continuous boiling of the fluid zone is achieved.

[0020] 3. Beneficial effects

[0021] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0022] The heat dissipation system of the present invention lays multiple layers of movable particles on the bottom wall of the boiling pool, so that heat is gathered near the particle layer, so that the liquid here boils faster, and the pits and pores between the particles and the boiling pool will give priority to the generation of vaporization cores. At the same time, the movable particles are used to maintain the wet state of the liquid in the process of boiling phase change heat transfer, ensuring the adhesion and migration effect on the phase change interface during the boiling process; in addition, because the movable particles have good thermal conductivity, heat is not only transferred from the bottom micro-liquid layer and the nearby superheated liquid to the bubbles, but also from the surrounding particles to the bubbles. When the particles move and contact with the bubbles, the particles transfer the adsorbed heat to the bubbles, thereby enhancing the growth rate of the bubbles; when the particles jump up and down, the bubbles will be broken due to the collision of the particles, accelerating the detachment of the bubbles; and when the particles fall down, the tiny cold fluid is brought into the superheated fluid, accelerating the detachment of the large bubble bag on the surface, destroying the steam film that deteriorates the heat transfer formed under the high heat flow on the surface, thereby enhancing the overall boiling heat transfer effect of the device and improving the heat transfer capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the heat dissipation system of the present invention;

[0024] Figure 2 Schematic diagram of the porous microparticle structure of the present invention;

[0025] Wherein (a) is the cross-sectional structure of porous microparticles, (b) is the cross-sectional structure of hollow microparticles, and (c) is the surface porous structure of microparticles;

[0026] Figure 3 Schematic diagram of bubble nucleation in the present invention;

[0027] Figure 4 It is a schematic diagram of bubble growth in the present invention;

[0028] Figure 4 The q1 in the equation represents the heat transferred from the particles to the bubbles, and the q2 represents the heat transferred from the bottom of the boiling pool.

[0029] Figure 5 It is a schematic diagram of bubble separation in the present invention;

[0030] Figure 6 Schematic diagram of particles impacting bubbles in the present invention;

[0031] Figure 7 It is a top view of the migration of hot spots on the heated wall surface in the present invention.

[0032] Explanation of the symbols in the schematic diagram:

[0033] 1. Boiling pool; 2. Movable particles; 21. Microparticle skeleton; 22. Microparticles are porous; 23. Microparticles are hollow;

[0034] 3. Heat conducting layer; 4. Heat source; 5. Pipeline; 6. Condenser; 7. Bubbles. DETAILED DESCRIPTION

[0035] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] The present invention will be further described below in conjunction with the embodiments.

[0038] Example

[0039] Combination Figure 1-Figure 7As shown, this embodiment provides a high-efficiency passive heat dissipation system based on particle movement, including a boiling pool 1, a pipe 5 and a condenser 6. The boiling pool 1 is filled with a fluid medium. In practice, the fluid medium can be water, methanol, ethanol, Freon, etc.; the bottom wall of the boiling pool 1 has a heat-conducting layer 3 for transferring heat from a heat source 4, and the heat-conducting layer 3 is used to transfer the heat of the heat source 4 to the boiling pool 1; in practice, it is preferred to directly use the bottom wall of the boiling pool 1 as the heat-conducting layer 3, and receive and transfer heat through the bottom wall of the boiling pool 1; movable particles 2 are laid in the boiling pool 1; the inlet and outlet of the pipe 5 are respectively connected to the inner cavity of the boiling pool 1, and a condenser 6 is provided on the outside of the pipe 5. Combined with the attached Figure 1 The system is used to quickly dissipate the heat generated by the heat source 4. In practice, the heat source 4 can be a single group or multiple groups, which can be randomly distributed, etc., and the heat is conducted to the boiling pool 1 through the heat conductive layer 3.

[0040] In practice, the movable particles 2 are metal microparticles, and the thermal conductivity of the metal microparticles is not less than 20W / (m·K), and preferably copper, aluminum, and the like are used. The particle size of the movable particles 2 is 5 to 250μm. In addition, the heat-conducting layer 3 is also preferably made of a high thermal conductivity material, and the thermal conductivity of the heat-conducting layer 3 is not less than 100W / (m·K), and preferably copper, aluminum, and the like are used.

[0041] Combination Figure 2 As shown, in this embodiment, the surface of the movable particle 2 has a hydrophilic porous liquid storage structure, which ensures the wetting of the liquid to provide continuous boiling of the particle surface and can move freely during the boiling heat transfer process. Specifically, the movable particle 2 includes a microparticle skeleton 21, and a plurality of microparticle porous 22 formed on the surface of the microparticle skeleton 21. More preferably, a microparticle hollow portion 23 is formed in the middle of the microparticle skeleton 21 of the movable particle 2, and the microparticle porous 22 on the surface is connected to the microparticle hollow portion 23 in the center to further enhance the liquid storage capacity. These surface porous structures help to enhance the liquid storage capacity of the movable particle 2, ensure the wetting of the movable particle 2 to achieve the migration effect on the gas-liquid interface. In addition, while increasing the vaporization core of the boiling heat transfer, it is beneficial to re-boiling bubbles to promote their free movement in the liquid working medium to further enhance heat transfer.

[0042] In practice, the amount of movable particles 2 laid should at least reach 2-5 layers covering the heating surface, such as covering 2-5 layers of the bottom wall of the boiling pool 1. Furthermore, the movement range of the movable particles 2 can be constrained by the frame, and the size of the range can be subdivided according to the needs to achieve more precise constraints on the movable particles 2. For example, in this embodiment, a partition net is preferably provided on the bottom wall of the boiling pool 1, and the partition net is evenly divided into multiple placement areas at the bottom of the boiling pool 1, and the movable particles 2 are laid in each placement area. Figure 7As shown, the partition net can be evenly divided into nine spaces on the bottom wall of the boiling pool 1, so that the movable particles 2 can be distributed in each area. The jumping of the particles can quickly carry heat to the interior of the fluid to enhance boiling heat transfer. When the particles fall back to the heating surface and hit the bubbles, the detachment of the bubbles is accelerated, and the steam film formed under high heat flow can be destroyed, delaying the occurrence of film boiling that deteriorates heat transfer.

[0043] Furthermore, in order to prevent the movable particles 2 from entering the pipe 5, the boiling pool 1 is provided with particle barrier nets at the inlet and outlet of the pipe 5, respectively, and the particle barrier nets can limit the movable particles 2 in the boiling pool 1 from entering the pipe 5. The liquid level of the fluid medium in the boiling pool 1 is lower than the height of the inner cavity of the boiling pool 1, and the outlet and inlet positions of the pipe 5 connected to the boiling pool 1 are both below the liquid level of the fluid medium.

[0044] The purpose of this embodiment is to provide a system for efficient phase change heat dissipation, in which the phase change part is to transfer heat to the boiling pool 1 through the heat conducting layer 3, and the pores in the pits between the movable particles 2 and the movable particles 2, and between the movable particles 2 and the boiling pool 1 will preferentially act as active vaporization nucleation points, which is more conducive to the generation of vaporization cores. At the same time, since the movable particles 2 have good thermal conductivity, heat is not only conducted to the bubbles 7 from the bottom micro-liquid layer and the nearby superheated liquid, but also transferred to the bubbles 7 from the surrounding movable particles 2. When the movable particles 2 move and contact with the bubbles 7, the movable particles 2 transfer the adsorbed heat to the bubbles 7, thereby enhancing the growth rate of the bubbles 7. When the movable particles 2 jump up and down, the bubbles 7 will be broken due to the collision of the movable particles 2, which accelerates the separation of the bubbles 7. The movable particles 2 are constantly moving in the boiling pool 1, so that the heat can be more evenly distributed in the whole pool, avoiding the overheating phenomenon caused by local heat accumulation. Moreover, the movable particles 2 form a porous structure between the movable particles 2 and the bubbles 7, thereby enhancing the porous phase change effect. When the liquid is heated to boil and bubbles 7 are generated, these movable particles 2 will move around with the convection of the liquid and the rising and bursting of the bubbles 7. Their movement will drive the surrounding liquid to flow together, thereby enhancing the boiling heat transfer in the bottom liquid area.

[0045] The following combination Figure 3-Figure 7 The heat dissipation system of this embodiment is described in detail:

[0046] Figure 3 , 4 , 5 are schematic diagrams of bubble nucleation, growth, and detachment. Figure 1The figure shows a schematic diagram of the working state of the heat dissipation system. When the heat source 4 is dissipated, the heat is quickly transferred to the boiling pool 1 through the heat conductive layer 3. Due to the increase in heat, there is a thin fluid layer with a dramatic temperature change near the heating surface. The movable particles 2 form a porous structure between the particles and the bubbles, which improves the porous phase change effect. At the same time, the movement and up and down jumping of the movable particles 2 are used to strengthen the flow field disturbance in the boiling pool 1 and strengthen the boiling heat transfer in the bottom liquid area. At the same time, when the movable particles 2 are accumulated on the heating surface to form a porous structure, the heat accumulates near the particle layer, causing the liquid near the particles to overheat faster, thereby accelerating the boiling speed. The heat is not only conducted to the bubbles from the bottom micro-liquid layer and the nearby superheated liquid, but also from the surrounding particles to the bubbles. When the particles come into contact with the bubbles during movement, the particles transfer the adsorbed heat to the bubbles, increasing the bubble growth rate, which is conducive to the detachment of the bubbles and effectively avoiding the phenomenon of local overheating.

[0047] Figure 6 This is a schematic diagram of the movable particle 2 colliding with the bubble. Figure 7 The top view of the hot spot change migration on the heating wall surface is shown. Due to the high thermal conductivity of the movable particle 2, the position of the hot spot will migrate as the movable particle 2 moves. In addition, since the movable particle 2 can move freely, during the up and down movement, the movable particle 2 not only disturbs the thermal boundary layer and destroys the steam film on the heating surface under the high heat flow when it hits the heating surface, but also carries the cold fluid back to the overheating area, thereby enhancing the heat exchange. On the other hand, due to the arrangement of the movable particles 2, the heat transfer area is increased, thereby achieving the effect of rapid heat transfer. When the steam enters the pipe 5, the steam pushes the working fluid to flow to the condenser 6 position. In the condensation area, the bubbles cool and shrink after releasing heat, and the pressure drops, thus forming a pressure difference in the flow channel. In addition, the pressure imbalance between the adjacent tubes causes the working fluid to flow randomly between the evaporation section and the condensation section, thereby achieving efficient heat transfer with the help of pulsating flow and phase change heat transfer.

[0048] The above is a schematic description of the present invention and its implementation mode, which is not restrictive and is only one of the implementation modes of the present invention, and is not actually limited thereto. Therefore, if a person skilled in the art is inspired by it and, without departing from the purpose of the invention, designs a structure and an implementation mode similar to the technical solution without creativity, they shall all fall within the protection scope of the present invention.

Claims

1. An efficient passive heat dissipation system based on particle movement, characterized in that: The invention comprises a boiling pool (1), a pipeline (5) and a condenser (6); the boiling pool (1) is filled with a fluid medium; the bottom wall of the boiling pool (1) has a heat-conducting layer (3) for transferring heat from a heat source (4); the heat-conducting layer (3) is used to transfer the heat from the heat source (4) to the boiling pool (1); movable particles (2) are laid in the boiling pool (1); the inlet and outlet of the pipeline (5) are respectively connected to the inner cavity of the boiling pool (1), and the condenser (6) is arranged outside the pipeline (5).

2. The high-efficiency passive heat dissipation system based on particle movement according to claim 1, characterized in that: The surface of the movable particle (2) has a hydrophilic porous liquid storage structure.

3. The high-efficiency passive heat dissipation system based on particle movement according to claim 2, characterized in that: The movable particle (2) includes a microparticle skeleton (21) and a plurality of microparticle pores (22) formed on the surface of the microparticle skeleton (21).

4. The high-efficiency passive heat dissipation system based on particle movement according to claim 3, characterized in that: A microparticle hollow portion (23) is formed in the middle of the microparticle skeleton (21) of the movable particle (2), and the microparticle pores (22) on the surface are connected to the microparticle hollow portion (23) in the center.

5. The high-efficiency passive heat dissipation system based on particle movement according to claim 2, characterized in that: The movable particles (2) are metal microparticles, and the thermal conductivity of the metal microparticles is not less than 20 W / (m·K).

6. The high-efficiency passive heat dissipation system based on particle movement according to claim 1, characterized in that: A partition net is provided on the bottom wall of the boiling pool (1), and the partition net evenly divides the bottom of the boiling pool (1) into a plurality of placement areas, and the movable particles (2) are respectively laid in each placement area.

7. A high-efficiency passive heat dissipation system based on particle movement according to any one of claims 1 to 6, characterized in that: Particle blocking nets are respectively arranged on the boiling pool (1) at the inlet and outlet positions of the pipeline (5), and the particle blocking nets can restrict movable particles (2) in the boiling pool (1) from entering the interior of the pipeline (5).

8. The high-efficiency passive heat dissipation system based on particle movement according to claim 1, characterized in that: The particle size of the movable particles (2) is 5 to 250 μm.

9. The high-efficiency passive heat dissipation system based on particle movement according to claim 1, characterized in that: The thermal conductivity of the heat-conducting layer (3) is not less than 100 W / (m·K).

10. The high-efficiency passive heat dissipation system based on particle movement according to claim 1, characterized in that: The liquid level of the fluid medium in the boiling pool (1) is lower than the inner cavity height of the boiling pool (1), and the inlet and outlet positions of the pipeline (5) communicating with the boiling pool (1) are both below the liquid level of the fluid medium.

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