Phase change heat dissipation device

Abstract

The invention relates to the field of heat dissipation devices, and provides a phase change heat dissipation device. The phase change heat dissipation device comprises a sealed cavity, and the sealed cavity is provided with a heat transfer face used for making contact with a heat source, a working medium inlet and a working medium outlet. The macroscopic turbulent flow structure is arranged in the sealing cavity and is used for generating a transverse velocity component and a secondary flow in a working medium flowing through the sealing cavity so as to damage and reconstruct a near-wall boundary layer; and the microscopic nucleation structure is arranged on the heat transfer surface or the surface of the macroscopic turbulent flow structure and is used for providing bubble nucleation points. The phase change heat dissipation device can accelerate heat transfer, start nucleate boiling in advance, effectively meet the requirement for high-heat-flux heat dissipation and solve the problem that a traditional device is low in heat exchange efficiency. The limitation that a traditional phase change heat dissipation device is prone to failure under the high heat flux density is broken through, and the application range is expanded.

Description

Phase change heat dissipation device Technical Field

[0001] This invention relates to the field of heat dissipation devices, and provides a phase change heat dissipation device. Background Technology

[0002] In the thermal management of high-power-density electronic devices, traditional cooling methods, such as single-phase liquid cooling, are increasingly unable to meet the growing heat dissipation demands. Against this backdrop, phase change cooling, as a novel cooling technology, significantly improves cooling efficiency by utilizing the latent heat generated during the phase change process of the cooling medium. It is particularly suitable for the thermal management of high-heat-generating devices such as power electronics, computing accelerator chips, and energy storage devices. The basic principle of phase change cooling is that the cooling medium undergoes a phase change (liquid to gas) at its surface. During this process, it can carry away a large amount of heat, thereby effectively reducing the temperature of the device.

[0003] However, achieving both high heat flux density and good thermal uniformity in a phase change heat exchanger is not easy. This is because the phase change heat exchange efficiency is affected by the two-phase flow pattern distribution, especially during boiling, where the generation and detachment of bubbles from the surface significantly impact overall heat exchange performance. Traditional smooth or single rough surfaces require high wall superheat for bubble nucleation (i.e., bubble formation starting from the surface), which delays the onset of nucleated boiling and increases thermal resistance. Once bubbles are generated and fail to detach from the surface and be carried away by the fluid in time, they accumulate in the heated area to form a vapor film, hindering liquid replenishment and causing a sharp decline in heat exchange performance near the critical heat flux density (CHF, i.e., maximum heat flux capacity).

[0004] Therefore, current research typically focuses on optimizing a single aspect, such as enhancing bubble formation by creating micropores or roughening the surface, or promoting bubble detachment through tortuous designs. However, this decentralized optimization neglects the coupling characteristics between flow and phase change effects during the phase transition process, often increasing the optimization cost of one aspect while improving another. For example, while microporous structures can improve bubble formation, they increase surface frictional resistance; and while tortuous channels help expel bubbles, they can easily cause localized pressure drop effects. Summary of the Invention

[0005] This invention provides a phase change heat dissipation device to address the shortcomings of related technologies where phase change heat dissipation devices struggle to simultaneously achieve efficient heat dissipation and reduce resistance.

[0006] This invention provides a phase change heat dissipation device, comprising: a sealed cavity having a heat transfer surface for contact with a heat source, a working fluid inlet, and a working fluid outlet; a macroscopic turbulence structure disposed within the sealed cavity for generating a transverse velocity component and secondary flow in the working fluid flowing through the sealed cavity, thereby disrupting and rebuilding the near-wall boundary layer; and a microscopic nucleation structure disposed on the surface of the heat transfer surface or the macroscopic turbulence structure for providing bubble nucleation points to reduce the wall superheat required for boiling.

[0007] According to one embodiment of the present invention, the macroscopic disturbance structure is a geometric structure that forms periodic or non-periodic disturbances in the main flow direction of the working fluid, and the macroscopic disturbance structure includes non-linear channels or discontinuous array structures.

[0008] According to one embodiment of the present invention, the macroscopic turbulence structure includes at least one of the following: a corrugated fin structure, a biomimetic shark fin structure, a streamlined teardrop-shaped flow guide structure, a serrated channel structure, or a twisted channel structure.

[0009] According to one embodiment of the present invention, the macroscopic turbulence structure is further used to apply hydrodynamic shear to the bubbles generated on the heat transfer surface or the surface of the macroscopic turbulence structure, so as to cause the bubbles to detach from the surface of the macroscopic turbulence structure and be carried away by the flowing working fluid.

[0010] According to one embodiment of the present invention, the micronucleation structure is locally arranged in the main heated area or the flow-facing area of ​​the heat transfer surface.

[0011] According to one embodiment of the present invention, the micronucleation structure includes at least one of micropores, micropits, microchannels, or porous sintered layers.

[0012] According to one embodiment of the present invention, the phase change heat dissipation device further includes a top cavity, which is disposed on the upper part of the sealed cavity and communicates with the flow channel where the macroscopic turbulence structure is located.

[0013] According to one embodiment of the present invention, the inner wall of the top cavity has a flat, gradually expanding or streamlined structure, and its flow cross-sectional area gradually increases along the flow direction of the working medium or in the vertical upward direction, so as to adapt to the volume expansion of the working medium after the phase change and reduce the exhaust resistance of the gaseous working medium.

[0014] According to one embodiment of the present invention, the top cavity is used to perform gas-liquid separation on the working fluid entering the top cavity, and to buffer pressure pulsations caused by phase change and boiling.

[0015] According to one embodiment of the present invention, the working fluid outlet is positioned higher in the vertical direction than the working fluid inlet, and the height difference between the working fluid outlet and the working fluid inlet is used to establish a natural pressure gradient within the sealed cavity, so as to realize gas-liquid stratified flow and spontaneous steam discharge by utilizing the coupling effect of static pressure and buoyancy.

[0016] According to the phase change heat dissipation device provided in the embodiments of the present invention, the macroscopic turbulence structure disrupts the near-wall boundary layer, accelerating heat transfer; the microscopic nucleation structure reduces wall superheat, initiating nucleation boiling earlier. Both the macroscopic turbulence structure and the microscopic nucleation structure significantly improve the phase change heat transfer efficiency, effectively addressing the heat dissipation requirements of high heat flux density and solving the problem of low heat transfer efficiency in traditional devices. The hydrodynamic shear force of the macroscopic turbulence structure promotes rapid bubble detachment, preventing bubble aggregation and the formation of a vapor film that hinders heat transfer, significantly increasing the critical heat flux density and solving the problem of heat transfer deterioration caused by bubble retention in traditional devices. The non-linear design of the macroscopic turbulence structure enhances heat transfer while avoiding a surge in flow resistance through optimized morphology and layout; the variable density or variable cross-section design of the macroscopic turbulence structure (such as densification in hot spot areas) achieves precise matching between heat dissipation capacity and heat source heat flux distribution, effectively eliminating local hot spots and preventing heat transfer deterioration. The localized arrangement of the microscopic nucleation structure reduces obstruction to the working fluid flow, achieving a balance between high heat transfer efficiency and low flow resistance, and reducing the energy consumption required for working fluid circulation. The top-mounted cavity design follows the volume expansion law of the working fluid from liquid to gas, significantly reducing exhaust resistance, flow pressure drop, and pump power loss. The capillary effect of the micro-nucleation structure promotes liquid replenishment, maintains the wetted state of the heat transfer surface, and avoids local drying; the macro-turbulence structure ensures uniform mixing of the working fluid and stable temperature distribution. Together, these factors reduce fluctuations in phase change heat transfer and improve the heat transfer stability of the device. The high-efficiency heat transfer performance and stable operation make the device suitable for high heat flux density electronic devices, power modules, and other applications, overcoming the limitation of traditional phase change heat dissipation devices being prone to failure under high heat flux density and expanding its application range. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 is a schematic perspective view of the phase change heat dissipation device provided by the present invention.

[0019] Figure 2 is a schematic perspective view of the phase change heat dissipation device provided by the present invention.

[0020] Figure 3 is a schematic diagram of the working fluid flow in the phase change heat dissipation device provided by the present invention.

[0021] Figure 4 is a schematic structural diagram of a macroscopic disturbance structure provided by the present invention.

[0022] Figure 5 is a schematic structural diagram of another macroscopic disturbance structure provided by the present invention.

[0023] Figure 6 is a schematic top view of the phase change heat dissipation device provided by the present invention.

[0024] Figure 7 is a schematic side view of the phase change heat dissipation device provided by the present invention.

[0025] Figure 8 is a schematic structural diagram of the micro-nucleation structure provided by the present invention.

[0026] Reference numerals: 100, sealed cavity; 102, working fluid inlet; 104, working fluid outlet; 106, macroscopic turbulence structure; 108, microscopic nucleation structure; 110, top cavity. Detailed Implementation

[0027] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0028] As shown in Figures 1 to 8, an embodiment of the present invention provides a phase change heat dissipation device, comprising: a sealed cavity 100 having a heat transfer surface for contact with a heat source, a working fluid inlet 102, and a working fluid outlet 104; a macroscopic turbulence structure 106 disposed within the sealed cavity 100 for generating a transverse velocity component and secondary flow in the working fluid flowing through the sealed cavity 100 to disrupt and rebuild the near-wall boundary layer; and a microscopic nucleation structure 108 disposed on the surface of the heat transfer surface or the macroscopic turbulence structure 106 for providing bubble nucleation points to reduce the wall superheat required for boiling.

[0029] According to the phase change heat dissipation device provided in the embodiments of the present invention, the macroscopic turbulence structure 106 disrupts the near-wall boundary layer, accelerating heat transfer; the microscopic nucleation structure 108 reduces wall superheat and initiates nucleation boiling earlier. The macroscopic turbulence structure 106 and the microscopic nucleation structure 108 significantly improve the phase change heat transfer efficiency, effectively meeting the heat dissipation requirements of high heat flux density and solving the problem of low heat exchange efficiency in traditional devices. The hydrodynamic shear force of the macroscopic turbulence structure 106 promotes rapid bubble detachment, preventing bubble aggregation and the formation of a vapor film that hinders heat transfer, significantly increasing the critical heat flux density and solving the problem of heat transfer deterioration caused by bubble retention in traditional devices. The non-linear design of the macroscopic turbulence structure 106 enhances heat transfer while avoiding a surge in flow resistance through optimized morphology and layout; the localized arrangement of the microscopic nucleation structure 108 reduces obstruction to the working fluid flow, achieving a balance between high heat transfer efficiency and low flow resistance, and reducing the energy consumption required for working fluid circulation. The capillary effect of the micro-nucleation structure 108 promotes liquid replenishment, maintains the wettability of the heat transfer surface, and prevents localized drying. The macro-turbulence structure 106 ensures uniform mixing of the working fluid and stable temperature distribution. Together, these two elements reduce fluctuations in phase change heat transfer and improve the heat transfer stability of the device. The high heat transfer efficiency and stable operation make the device suitable for high heat flux density electronic devices, power modules, and other applications, overcoming the limitations of traditional phase change heat dissipation devices that are prone to failure under high heat flux density and expanding its application range.

[0030] Please refer to Figures 1 to 8. The phase change heat dissipation device provided in this embodiment of the invention achieves a balance between high-efficiency phase change heat dissipation and low flow resistance through the synergistic design of macroscopic turbulence and microscopic nucleation.

[0031] The sealed cavity 100 has a closed structure and can be made of high thermal conductivity metals or composite materials to ensure rapid heat conduction.

[0032] A heat transfer surface is provided on one side of the sealed cavity 100, which is in close contact with the heat source. The heat transfer surface is flat and smooth, which increases the contact area with the heat source and improves the heat transfer efficiency.

[0033] The working fluid inlet 102 is located at the bottom of the cavity to facilitate the rapid arrival of the liquid working fluid at the heat transfer surface; the working fluid outlet 104 is located at the top of the cavity to facilitate the discharge of the gaseous working fluid. The internal space of the sealed cavity 100 is adapted to accommodate the installation of the macroscopic turbulence structure 106 to ensure smooth flow of the working fluid.

[0034] The macroscopic turbulence structure 106 is disposed inside the sealed cavity 100, above the heat transfer surface, and maintains a preset distance from the heat transfer surface. The macroscopic turbulence structure 106 has a non-linear geometry and can be corrugated, staggered, spiral, sawtooth, or twisted, etc., forming periodic or non-periodic disturbances in the main flow direction of the working fluid. The macroscopic turbulence structure 106 is uniformly distributed within the sealed cavity 100. When the working fluid flows through it, it generates a transverse velocity component and secondary flow, destroying and rebuilding the near-wall boundary layer, while simultaneously applying hydrodynamic shear force to the generated bubbles.

[0035] The micro-nucleation structures 108 are arranged in the main heated area or the flow-facing region of the heat transfer surface, or on the surface of the macro-turbulence structure 106. The micro-nucleation structures 108 are arranged locally to avoid increased flow resistance caused by full surface coverage. The morphology of the micro-nucleation structures 108 includes micropores, micro-pits, microchannels, or porous sintered layers, formed through precision machining processes, and is firmly bonded to the substrate, providing a high density of bubble nucleation points. The capillary effect of the micro-nucleation structures 108 promotes liquid replenishment and maintains the wettability of the heat exchange surface.

[0036] Liquid working fluid enters the sealed cavity 100 through working fluid inlet 102. As it flows through the macroscopic turbulence structure 106, a secondary flow is generated under the influence of turbulence, rapidly covering the heat transfer surface. The microscopic nucleation structure 108 reduces the wall superheat required for boiling, allowing the working fluid to vaporize and generate bubbles at a relatively low temperature difference. The hydrodynamic shear force generated by the macroscopic turbulence structure 106 causes the bubbles to quickly detach from the heat transfer surface and structural surface, being carried away by the mainstream working fluid, preventing the formation of a vapor film. The bubbles flow with the working fluid to the working fluid outlet 104 and are discharged. The liquid working fluid continuously replenishes the heat transfer surface under the action of secondary flow and capillary effect, forming a stable phase change heat cycle.

[0037] According to one embodiment of the present invention, the macroscopic disturbance structure 106 is a geometric structure that forms periodic or non-periodic disturbances in the main flow direction of the working fluid; the macroscopic disturbance structure 106 includes non-linear channels or discontinuous array structures.

[0038] In one embodiment of the present invention, the macroscopic turbulence structure 106 generates periodic or non-periodic disturbances in the main flow direction of the working fluid. The macroscopic turbulence structure 106 is integrally arranged inside the sealed cavity 100, maintaining a preset distance from the heat transfer surface, and is evenly distributed along the working fluid flow path, without blocking the flow channel, ensuring smooth passage of the working fluid. The shape of the macroscopic turbulence structure 106 can be adjusted according to the flow channel size and heat dissipation requirements to adapt to different working fluid flow velocities and heat exchange scenarios.

[0039] When the working fluid flows through the macroscopic turbulence structure 106, its flow direction is forcibly changed, generating a transverse velocity component outside the main flow direction, forming a secondary flow. The periodic turbulence structure makes this secondary flow change regularly, while the non-periodic structure generates random turbulence. Both forms can break the near-wall boundary layer of the working fluid, avoiding the decrease in heat transfer efficiency caused by an excessively thick boundary layer.

[0040] The height and width of the macroscopic disturbance structure 106 are adapted to the size of the sealed cavity 100, generating effective disturbance without significantly increasing flow resistance.

[0041] The macroscopic disturbance structure 106 can be made of a high thermal conductivity material, which is the same as or compatible with the material of the sealed cavity 100, ensuring that heat can be conducted through the structure and avoiding local heat accumulation. The structure can be processed by metal 3D printing, CNC milling and other processes to ensure the precise forming of the macroscopic disturbance structure 106.

[0042] According to one embodiment of the present invention, the macroscopic turbulence structure 106 includes at least one of the following: a corrugated fin structure, a biomimetic shark fin structure, a streamlined teardrop-shaped flow guide structure, a serrated channel structure, or a twisted channel structure.

[0043] In one embodiment of the invention, the corrugated fin structure is a continuous wave shape, extending along the main flow direction of the working fluid, with alternating crests and troughs forming periodic disturbances. The height, wavelength, and amplitude of the fins are optimized to ensure stable lateral velocity components and secondary flow when the working fluid flows through them. The structure is uniformly distributed above the heat transfer surface within the sealed cavity 100, maintaining a preset distance from the heat transfer surface, thus neither blocking the flow channel nor obstructing the heat exchange area. The fins are made of the same material as the sealed cavity 100, possessing good thermal conductivity, which helps transfer heat and avoids localized heat accumulation.

[0044] The biomimetic shark fin structure mimics the shape of a shark fin, consisting of multiple independent fin units arranged in a cross-shaped network to form a flow-disrupting structure. Each fin unit is streamlined, with its thickness gradually decreasing from the root to the tip, reducing flow resistance. The arrangement density and intersection angle of the fin units have been optimized through fluid dynamics, generating a complex and uniform secondary flow as the working fluid flows through it, creating omnidirectional hydrodynamic shearing of the bubbles. The entire structure is fixed within a sealed cavity 100, forming a preset angle with the flow direction of the working fluid, ensuring the flow-disrupting effect without significantly increasing pressure drop.

[0045] The streamlined teardrop-shaped flow guide structure is teardrop-shaped with a smooth, edgeless surface and is arranged along the flow direction of the working fluid. The front end of the structure is rounded and gradually tapers to a point at the rear, guiding the working fluid smoothly and reducing eddy current losses. Multiple flow guide structures are distributed in an array, with spacing adapted to the channel size, dividing the working fluid into multiple streams during flow. Each stream generates lateral disturbances, disrupting the near-wall boundary layer. The structure's axis is parallel to the main flow direction of the working fluid, ensuring smooth flow guidance, while its smooth surface reduces frictional resistance during flow.

[0046] The serrated channel structure generates disturbance through serrated protrusions on the channel wall. The tooth height, tooth pitch, and inclination angle are designed to create localized high-speed flow zones at the tooth tips as the working fluid flows through, exerting a shearing effect on the bubbles. The overall orientation of the channel is consistent with the flow direction of the working fluid, and the serrated protrusions are evenly distributed along the inner wall of the channel, ensuring that the working fluid throughout the entire channel is disturbed. The smooth inner wall of the structure and the gradual transition of the serrations avoid flow instability caused by sudden changes in local pressure.

[0047] The twisted channel structure causes the entire flow channel to spiral, forcing the working fluid to rotate during flow and forming a strong axial and radial combined secondary flow. The twist angle and pitch of the channel are optimized to balance the turbulence intensity and flow resistance, allowing the working fluid to mix fully in the rotating flow and disrupting the near-wall boundary layer. The two ends of the structure smoothly connect to the flow channel, ensuring smooth entry and exit of the working fluid without impact loss, and adapting to the heat exchange requirements of high-velocity working fluids.

[0048] According to one embodiment of the present invention, the macroscopic turbulence structure 106 is also used to apply hydrodynamic shear to the bubbles generated on the heat transfer surface or the surface of the macroscopic turbulence structure 106, so as to cause the bubbles to detach from the surface of the macroscopic turbulence structure 106 and be carried away by the flowing working fluid.

[0049] In one embodiment of the invention, the non-linear shape of the macroscopic turbulence structure 106 causes local velocity changes as the working fluid flows through it, generating hydrodynamic shear force. This shear force acts on bubbles generated on the heat transfer surface or structural surface, disrupting the adhesion between the bubbles and the surface and causing the bubbles to detach rapidly.

[0050] The protrusions or bends of the macroscopic turbulence structure 106 create local high-speed flow zones, which scour the attached bubbles; the depressions create low-pressure zones, attracting liquid back to replenish the flow and further weakening the bubble adhesion. The periodic structure causes the shear force to act in a regular manner, while the non-periodic structure improves the comprehensiveness of debubbling through random perturbations.

[0051] The layout of the macroscopic turbulence structure 106 is adapted to the flow direction of the working fluid, ensuring that the direction of the shear force is consistent with the direction of bubble detachment. This allows the detached bubbles to be quickly carried away by the mainstream working fluid and not remain near the heat transfer surface. The distance between the structure and the heat transfer surface ensures that the shear force can cover all bubble generation areas, eliminating any dead zones in the debubbling process.

[0052] The design of the macroscopic turbulence structure 106 generates sufficient shear force without excessively disturbing the flow of the working fluid, thus avoiding a surge in flow resistance due to defoaming and achieving a balance between defoaming effect and flow resistance.

[0053] According to one embodiment of the present invention, the micronucleation structure 108 is locally arranged in the main heated area or the flow-facing area of ​​the heat transfer surface.

[0054] In one embodiment of the invention, the micro-nucleation structures 108 are locally arranged in the main heated areas or the flow-facing areas of the heat transfer surface. These areas are where the working fluid first comes into contact with the heat source and where the heat is most concentrated, resulting in the highest demand for bubble nucleation. Localized arrangement avoids the increase in flow resistance caused by full surface coverage, balancing nucleation enhancement and flow resistance control.

[0055] The micro-nucleation structure 108 is formed on the surface of the heat transfer surface or the macro-turbulence structure 106 through precision machining, and is firmly bonded to the substrate, making it difficult to fall off. The distribution density of the structure is adjusted according to the regional heat flux density, with a higher density in the main heated area to ensure sufficient nucleation points, and the density in the flow-facing area is adapted to the impact strength of the working fluid to avoid structural damage.

[0056] When the micro-nucleation structure 108 is arranged on the surface of the macro-turbulence structure 106, its position avoids the key disturbance parts of the structure and does not affect the generation of secondary flow. At the same time, the secondary flow is used to promote the detachment of bubbles after nucleation, so as to achieve the synergy of nucleation and debubbling.

[0057] The material of the micronucleation structure 108 is compatible with the material of the heat transfer surface and the macroscopic turbulence structure 106. According to an embodiment of the present invention, the micronucleation structure 108 includes at least one of micropores, micro-pits, microchannels or porous sintered layers.

[0058] In one embodiment of the present invention, the microporous structure is a through-hole or blind hole, with a small and uniform pore size, distributed on the heat transfer surface or the surface of the macroscopic turbulence structure 106, providing dense nucleation points; the micro-pit structure is a surface depression, in the shape of a hemispherical or cylindrical shape, which can capture tiny bubbles in the working fluid and promote bubble growth; the microchannel structure is a narrow groove, arranged along the flow direction of the working fluid or perpendicular to the direction, which not only provides nucleation points, but also guides liquid replenishment; the porous sintered layer is a porous film covering the key heated area, forming a large number of tiny pores inside, which has both nucleation and capillary replenishment functions.

[0059] The structural parameters of various forms are adjusted according to the working fluid characteristics and heat dissipation requirements: the pore size and depth of micropores, the diameter and depth of micro-pits, the width and spacing of microchannels, and the porosity and thickness of porous sintered layers are all aimed at improving nucleation efficiency and promoting bubble detachment, while avoiding excessive flow resistance.

[0060] The micro-nucleation structure 108 is formed through processes such as chemical etching, laser drilling, and powder sintering, resulting in high processing precision and uniform structural dimensions. The porous sintered layer is fixed to the substrate surface by sintering or bonding, while other structures are integrally formed with the substrate, ensuring a strong connection and preventing detachment over long-term use.

[0061] The structure has a smooth surface without sharp edges, which avoids scratching the working medium or causing it to decompose. The material has good compatibility with the working medium and does not react chemically, ensuring the long-term stability of the nucleation effect.

[0062] According to one embodiment of the present invention, the phase change heat dissipation device further includes a top cavity 110, which is disposed on the upper part of the sealed cavity 100 and is connected to the flow channel where the macroscopic turbulence structure 106 is located.

[0063] In one embodiment of the present invention, the top cavity 110 is disposed at the upper part of the sealed cavity 100 and is directly connected to the flow channel where the macroscopic turbulence structure 106 is located, forming a vertically continuous space. The volume of the cavity is designed according to the size of the sealed cavity 100 and the working fluid flow rate, which can accommodate sufficient gaseous working fluid without occupying too much space, ensuring a compact device structure. The inner wall of the cavity is smooth, without protrusions or dead corners, to avoid gaseous working fluid retention.

[0064] After the working fluid flows through the macroscopic turbulence structure 106, the gas-liquid two-phase mixture flows upward into the overhead cavity 110. Because the density of the gaseous working fluid is less than that of the liquid phase, it accumulates upward under buoyancy, while the liquid working fluid flows back along the inner wall of the cavity or the lower part of the flow channel to the heat transfer surface region, achieving initial gas-liquid separation. The separated gaseous working fluid is discharged through the working fluid outlet 104, while the liquid working fluid continues to participate in the heat exchange cycle.

[0065] The cavity is aligned with the top of the macroscopic turbulence structure 106 to ensure that the mixed flow can smoothly enter the cavity without flow obstruction. The bottom of the cavity and the connection with the flow channel have a smooth transition, reducing flow resistance and promoting rapid reflux of the liquid working fluid.

[0066] The top cavity 110 can buffer the pressure pulsation generated during boiling. When the working fluid vaporization rate fluctuates, the volume of the cavity can absorb the pressure change, avoiding flow channel vibration or unstable working fluid flow caused by sudden pressure changes.

[0067] According to one embodiment of the present invention, the top cavity 110 has a flat, gradually expanding or streamlined structure; the flow cross-sectional area of ​​the top cavity 110 gradually increases along the flow direction of the working medium or in the vertical upward direction, so as to adapt to the volume expansion of the working medium after the phase change and reduce the exhaust resistance of the gaseous working medium.

[0068] In one embodiment of the present invention, the inner wall of the flat-type top cavity 110 is a smooth plane, with an overall flat structure and no obvious protrusions or depressions. Its flow cross-sectional area remains uniform along the flow direction of the working fluid, while slightly increasing in the vertical upward direction, forming a gently expanding space. The length and width of the cavity are adapted to the upper dimensions of the sealed cavity 100, and smoothly connect with the flow channel where the macroscopic turbulence structure 106 is located, ensuring that the working fluid can smoothly enter the cavity without flow obstruction. The smooth inner wall of the flat structure reduces the frictional resistance during the flow of gaseous working fluid, and adapts to the need for mild volume expansion after the phase change of the working fluid.

[0069] The inner wall of the gradually expanding top cavity 110 has a gradually expanding shape, with the flow cross-sectional area gradually increasing along the direction of the working fluid flow, while simultaneously expanding vertically upwards. The expansion angle is optimized to avoid local eddies caused by abrupt changes, ensuring a smooth transition in the working fluid flow. The inlet end of the cavity matches the flow channel size, and the outlet end cross-sectional area is designed according to the volume expansion ratio of the working fluid after phase change, ensuring sufficient capacity to accommodate the expanded gaseous working fluid and reducing pressure loss. The smooth transition of the inner wall of the gradually expanding structure guides the orderly flow of the gaseous working fluid, adapting to medium- to high-intensity working fluid volume expansion.

[0070] The streamlined top cavity 110 features a smooth, curved inner wall, simulating the optimal path for fluid flow. The cross-sectional area gradually increases along both the working fluid flow direction and the vertically upward direction. The curve profile is optimized for fluid dynamics, reducing boundary layer separation and eddy current losses during gaseous working fluid flow. Both the cavity's inlet and outlet employ a smooth transition design, precisely connecting with the flow channel and working fluid outlet 104, minimizing flow resistance throughout the entire process of the working fluid entering and exiting the cavity. This streamlined structure is suitable for high-speed gaseous working fluid flow, particularly in scenarios where the working fluid undergoes significant volume expansion after a phase change.

[0071] According to one embodiment of the present invention, the top cavity 110 is used to perform gas-liquid separation on the working fluid entering the top cavity 110 and to buffer pressure pulsations caused by boiling.

[0072] In one embodiment of the present invention, the top cavity 110 is connected to the flow channel where the macroscopic turbulence structure 106 is located. After the working fluid enters the cavity, the flow space suddenly expands and the flow velocity decreases. The gaseous working fluid gathers upward under the action of buoyancy, while the liquid working fluid flows back along the inner wall of the cavity or the bottom of the flow channel due to gravity. A simple flow guiding structure can be set inside the cavity to guide the gaseous working fluid to flow towards the working fluid outlet 104 and the liquid working fluid to flow back towards the heat transfer surface, thereby improving the separation efficiency.

[0073] During boiling, fluctuations in the vaporization rate of the working fluid can cause pressure changes within the sealed cavity 100. The volume of the top cavity 110 can absorb these pressure fluctuations. When the pressure increases, the gas inside the cavity is compressed, and when the pressure decreases, the gas expands, thereby buffering pressure pulsations and preventing sudden pressure changes.

[0074] The volume of the cavity is designed based on the volume of the sealed cavity 100, the flow rate of the working fluid, and the pressure fluctuation range. It must meet the residence time required for gas-liquid separation and also have sufficient buffer volume. The height and cross-sectional area of ​​the cavity are adapted to the flow velocity of the working fluid to ensure the effective realization of separation and buffering functions.

[0075] The cavity outlet is directly connected to the working fluid outlet 104, allowing the separated gaseous working fluid to be discharged quickly; the bottom of the cavity smoothly transitions to the flow channel, ensuring smooth reflux of the liquid working fluid and preventing stagnation.

[0076] According to one embodiment of the present invention, the working fluid outlet 104 is positioned higher in the vertical direction than the working fluid inlet 102. The height difference between the working fluid outlet 104 and the working fluid inlet 102 is used to establish a natural pressure gradient within the sealed cavity 100, so as to realize gas-liquid stratified flow and spontaneous steam discharge by utilizing the coupling effect of static pressure and buoyancy.

[0077] In one embodiment of the present invention, the working fluid inlet 102 is located at the lower part of the sealed cavity 100, near the bottom of the heat transfer surface, to facilitate the rapid arrival of the liquid working fluid at the heat transfer surface for heat exchange; the working fluid outlet 104 is located at the upper part of the sealed cavity 100, communicating with the top cavity 110 or directly located at the upper part of the flow channel, to ensure that the gaseous working fluid can be smoothly discharged. The height difference between the inlet and outlet is designed according to the height of the sealed cavity 100 and the characteristics of the working fluid to form a sufficient natural pressure gradient.

[0078] The height difference creates a natural pressure differential within the sealed cavity 100, with the pressure in the lower inlet area being higher than that in the upper outlet area. Under the coupling effect of static pressure and buoyancy, the working fluid is propelled from the inlet to the outlet. The gaseous working fluid gathers upward due to buoyancy and moves rapidly towards the outlet under the action of the pressure differential, while the liquid working fluid flows downward under the drive of the pressure differential, achieving gas-liquid stratified flow.

[0079] The height difference between the inlet and outlet, along with the overhead cavity 110, works synergistically. The overhead cavity 110 promotes gas-liquid separation, while the height difference accelerates the discharge of the separated gas phase and the reflux of the liquid phase, forming a more stable gas-liquid cycle. The inlet position avoids the key disturbance area of ​​the macroscopic turbulence structure 106, ensuring that the working fluid can smoothly enter the flow channel, while the outlet position is aligned with the gas phase accumulation area, improving exhaust efficiency.

[0080] The natural pressure difference generated by the height difference makes the working fluid flow more smoothly, avoiding excessive turbulence and pressure fluctuations caused by forced flow. At the same time, the gas-liquid stratified flow reduces the shearing effect at the gas-liquid interface, further improving the flow stability.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A phase change heat dissipation device, characterized in that, include: A sealed cavity (100) having a heat transfer surface for contact with a heat source, a working fluid inlet (102), and a working fluid outlet (104); a macroscopic turbulence structure (106) disposed within the sealed cavity (100) for generating a transverse velocity component and secondary flow in the working fluid flowing through the sealed cavity (100) to disrupt and rebuild the near-wall boundary layer; and a microscopic nucleation structure (108) disposed on the surface of the heat transfer surface or the macroscopic turbulence structure (106) for providing bubble nucleation points to reduce the wall superheat required for boiling.

2. The phase change heat dissipation device according to claim 1, characterized in that, The macroscopic disturbance structure (106) is a geometric structure that forms periodic or non-periodic disturbances in the main flow direction of the working fluid; the macroscopic disturbance structure includes non-linear channels or discontinuous array structures.

3. The phase change heat dissipation device according to claim 2, characterized in that, The macroscopic turbulence structure (106) includes at least one of the following: a corrugated fin structure, a biomimetic shark fin structure, a streamlined teardrop-shaped flow guide structure, a serrated channel structure, or a twisted channel structure.

4. The phase change heat dissipation device according to claim 3, characterized in that, The macroscopic turbulence structure (106) is also used to apply hydrodynamic shear to the bubbles generated on the heat transfer surface or the surface of the macroscopic turbulence structure (106), so as to cause the bubbles to detach from the surface of the macroscopic turbulence structure (106) and be carried away by the flowing working fluid.

5. The phase change heat dissipation device according to claim 1, characterized in that, The micronucleation structure (108) is locally arranged in the main heat-receiving area or the flow-facing area of ​​the heat transfer surface.

6. The phase change heat dissipation device according to claim 5, characterized in that, The micronucleation structure (108) includes at least one of micropores, micropits, microchannels or porous sintered layers.

7. The phase change heat dissipation device according to claim 1, characterized in that, The phase change heat dissipation device also includes a top cavity (110), which is located on the upper part of the sealed cavity (100) and is connected to the flow channel where the macroscopic turbulence structure (106) is located.

8. The phase change heat dissipation device according to claim 7, characterized in that, The top cavity (110) has a flat, gradually expanding or streamlined structure; the flow cross-sectional area of ​​the top cavity (110) gradually increases along the flow direction of the working medium or in the vertical upward direction, so as to adapt to the volume expansion of the working medium after the phase change and reduce the exhaust resistance of the gaseous working medium.

9. The phase change heat dissipation device according to claim 7, characterized in that, The top cavity (110) is used to perform gas-liquid separation on the working fluid entering the top cavity (110) and to buffer the pressure pulsation caused by phase change and boiling.

10. The phase change heat dissipation device according to any one of claims 1 to 9, characterized in that, The working fluid outlet (104) is positioned higher in the vertical direction than the working fluid inlet (102). The height difference between the working fluid outlet (104) and the working fluid inlet (102) is used to establish a natural pressure gradient within the sealed cavity (100) so as to achieve gas-liquid stratification flow and spontaneous steam discharge by utilizing the coupling effect of static pressure and buoyancy.

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