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 sealing shell, a micro-channel phase change heat exchange structure and a multi-stage flow channel structure. According to the phase change heat dissipation device, the gas-liquid working medium can flow along different paths, the liquid working medium continuously wets the heat exchange surface on the lower layer, the gas-phase working medium is rapidly discharged on the upper layer, the problems of bubble blockage, vapor film coverage and drying caused by gas-liquid mixed flow in a traditional device are thoroughly solved, and the stable and continuous heat exchange process is guaranteed; the working medium boiling effect is enhanced, each micro-channel can obtain sufficient working medium through uniform distribution of the multi-stage flow channels, the heat dissipation advantage of phase change latent heat is fully played, the heat exchange efficiency is far higher than that of traditional single-phase liquid cooling, and the requirement for high-heat-flux heat dissipation of the hundred watts per square centimeter level can be effectively met; and the blockage of bubbles on the backflow of the liquid working medium can be avoided, the working medium flows more smoothly, the working medium circulation efficiency is improved, and the system pressure drop and energy consumption are reduced.

Description

Technical Field

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

[0002] With the development of modern technology, the integration of chips, power electronic devices, and laser equipment is constantly increasing, and the heat flux density they generate is also rising sharply. Taking chips as an example, in order to support higher integration and operating performance, the heat flux density on a chip can reach hundreds of watts per square centimeter. Traditional single-phase liquid cooling systems, although they can effectively cool the temperature on the circuit board, are inadequate in dealing with such high heat flux densities due to the limitations of their heat transfer coefficient.

[0003] To address this challenge, existing technologies involve two-phase cooling, which aims to utilize the latent heat released by the working fluid during phase change to achieve efficient heat dissipation. This approach is suitable for compact cooling applications such as microchannels or small enclosed cold plates. The core of two-phase cooling technology lies in utilizing the absorption or release of heat by the liquid working fluid during boiling or condensation, thereby effectively removing the large amount of heat generated by the device. Compared to single-phase cooling, this method offers higher cooling efficiency and a greater heat flux density handling capacity.

[0004] However, in practical applications, gas-liquid mixing within microchannels or enclosed cold plates remains a major issue affecting cooling performance. When bubbles in the liquid coalesce to form vapor films or plugs, they hinder the return flow of the liquid working fluid, leading to insufficient cooling in localized areas. In severe cases, this can cause the cooling chamber to dry out and the heat transfer effect to deteriorate drastically. On the other hand, the periodic generation and detachment of bubbles can cause oscillations within the system, resulting in pressure fluctuations. Summary of the Invention

[0005] This invention provides a phase change heat dissipation device to solve the defect in related technologies that cannot ensure that the liquid phase region and the gas phase region maintain a stable separation state overall.

[0006] This invention provides a phase change heat dissipation device, comprising: The sealed housing is equipped with a working fluid inlet and a working fluid outlet. A microchannel phase change heat transfer structure is disposed within the sealed housing, and the microchannel phase change heat transfer structure includes multiple parallel microchannels; A multi-stage flow channel structure is disposed within the sealed housing, the multi-stage flow channel structure including a main flow channel, at least one secondary liquid flow channel and at least one secondary gas / two-phase flow channel; The main channel is connected to the working fluid inlet; At least one of the secondary liquid channels is disposed above the microchannel phase change heat exchange structure and is in fluid communication with the main channel and the microchannel phase change heat exchange structure. At least one of the secondary liquid channels is used to introduce liquid working fluid into the microchannel. The flow direction of the microchannel is perpendicular to the flow direction of the secondary liquid channel. At least one of the secondary gas / two-phase flow channels is disposed above the secondary liquid flow channel and is in fluid communication with the microchannel phase change heat transfer structure and the working fluid outlet, for collecting and exporting the gaseous working fluid generated in the microchannel.

[0007] According to one embodiment of the present invention, the sealing housing includes an upper cover plate and a lower substrate plate, the lower substrate plate being used to contact a heat source, and the microchannel phase change heat transfer structure being disposed within the lower substrate plate.

[0008] According to one embodiment of the present invention, the main flow channel, the secondary liquid flow channel, and the secondary gas / two-phase flow channel are formed within the upper cover plate.

[0009] According to one embodiment of the present invention, the upper cover plate and the lower substrate are assembled by brazing, diffusion welding or sealing bolts.

[0010] According to one embodiment of the present invention, the upper cover plate and the lower substrate are integrally formed by metal 3D printing technology.

[0011] According to one embodiment of the invention, the cross-section of the microchannel is arranged asymmetrically along its flow direction to form a pressure gradient for inducing gas-liquid partitioning.

[0012] According to one embodiment of the present invention, the liquid working fluid enters the microchannel phase change heat transfer structure via the working fluid inlet, the main flow channel, and the secondary liquid flow channel; The gaseous working fluid flows out of the working fluid outlet via the microchannel phase change heat transfer structure and the secondary gas / two-phase flow channel.

[0013] According to one embodiment of the present invention, the working fluid outlet is positioned higher than the microchannel phase change heat transfer structure to utilize the gravity effect to assist in the discharge of the gaseous working fluid.

[0014] According to one embodiment of the present invention, the cross-sectional shape of the microchannel is rectangular, trapezoidal, or inverted trapezoidal.

[0015] According to one embodiment of the present invention, the device is made of a high thermal conductivity metal or composite material, wherein the high thermal conductivity metal or composite material is selected from at least one of copper, aluminum, titanium alloy, graphite-reinforced composite metal or diamond composite metal.

[0016] According to the phase change heat dissipation device provided in this embodiment of the invention, the layered layout of multi-stage flow channels and the vertical staggered design of microchannels allow the gas and liquid working fluids to flow along different paths. The liquid working fluid continuously wets the heat exchange surface in the lower layer, while the gaseous working fluid is rapidly discharged in the upper layer. This completely solves the problems of bubble blockage, vapor film coverage, and drying caused by gas-liquid mixing in traditional devices, ensuring a stable and continuous heat exchange process. The parallel layout of microchannels increases the heat exchange area, the nucleation point design enhances the boiling effect of the working fluid, and the uniform distribution of multi-stage flow channels ensures that each microchannel receives sufficient working fluid, fully utilizing the heat dissipation advantages of latent heat of phase change. The heat exchange efficiency is far higher than that of traditional single-phase liquid cooling, effectively meeting the high heat flux density heat dissipation requirements at the level of hundreds of watts per square centimeter. The optimized design of the layered flow channels reduces the shear resistance at the gas-liquid interface, and the smooth inner walls of the microchannels and flow channels reduce friction resistance. The separate flow of gas and liquid avoids the obstruction of the liquid working fluid backflow by bubbles, making the working fluid flow smoother, improving the working fluid circulation efficiency, and reducing system pressure drop and energy consumption. By integrating the flow channel and microchannel design, gas-liquid separation is achieved within a limited space, eliminating the need for additional gas-liquid separation cavities or components. This results in a compact and highly integrated device that meets the packaging requirements of high-power-density devices, broadening its application scenarios. Stable gas-liquid separation flow avoids system oscillations and pressure fluctuations, reducing the impact and corrosion of the working fluid on the channel walls. Continuous liquid working fluid replenishment ensures that the heat exchange surface remains constantly wetted, preventing device damage caused by localized overheating and extending the device's lifespan and operational reliability. 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 This is a schematic perspective view of the phase change heat dissipation device provided by the present invention.

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

[0020] Figure 3 This is a schematic side view of the phase change heat dissipation device provided by the present invention.

[0021] Figure 4 This is a schematic bottom view of the phase change heat dissipation device provided by the present invention.

[0022] Figure label: 100. Sealed housing; 102. Working fluid inlet; 104. Working fluid outlet; 106. Main flow channel; 108. Secondary liquid flow channel; 110. Secondary gas / two-phase flow channel. Detailed Implementation

[0023] 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.

[0024] like Figures 1 to 4 As shown, an embodiment of the present invention provides a phase change heat dissipation device, comprising: The sealed housing 100 is provided with a working fluid inlet 102 and a working fluid outlet 104; A microchannel phase change heat transfer structure is disposed within a sealed housing 100. The microchannel phase change heat transfer structure includes multiple parallel microchannels. A multi-stage flow channel structure is disposed within a sealed housing 100. The multi-stage flow channel structure includes a main flow channel 106, at least one secondary liquid flow channel 108, and at least one secondary gas / two-phase flow channel 110. Among them, the main channel 106 is connected to the working fluid inlet 102; At least one secondary liquid flow channel 108 is disposed above the microchannel phase change heat exchange structure and is in fluid communication with the main flow channel 106 and the microchannel phase change heat exchange structure. The at least one secondary liquid flow channel 108 is used to introduce liquid working fluid into the microchannel. The flow direction of the microchannel is perpendicular to the flow direction of the secondary liquid flow channel 108. At least one secondary gas / two-phase flow channel 110 is disposed above the secondary liquid flow channel 108 and is in fluid communication with the microchannel phase change heat transfer structure and the working fluid outlet 104, for collecting and discharging the gaseous working fluid generated in the microchannel.

[0025] According to the phase change heat dissipation device provided in this embodiment of the invention, the layered layout of multi-stage flow channels and the vertical staggered design of microchannels allow the gas and liquid working fluids to flow along different paths. The liquid working fluid continuously wets the heat exchange surface in the lower layer, while the gaseous working fluid is rapidly discharged in the upper layer. This completely solves the problems of bubble blockage, vapor film coverage, and drying caused by gas-liquid mixing in traditional devices, ensuring a stable and continuous heat exchange process. The parallel layout of microchannels increases the heat exchange area, the nucleation point design enhances the boiling effect of the working fluid, and the uniform distribution of multi-stage flow channels ensures that each microchannel receives sufficient working fluid, fully utilizing the heat dissipation advantages of latent heat of phase change. The heat exchange efficiency is far higher than that of traditional single-phase liquid cooling, effectively meeting the high heat flux density heat dissipation requirements at the level of hundreds of watts per square centimeter. The optimized design of the layered flow channels reduces the shear resistance at the gas-liquid interface, and the smooth inner walls of the microchannels and flow channels reduce friction resistance. The separate flow of gas and liquid avoids the obstruction of the liquid working fluid backflow by bubbles, making the working fluid flow smoother, improving the working fluid circulation efficiency, and reducing system pressure drop and energy consumption. By integrating the flow channel and microchannel design, gas-liquid separation is achieved within a limited space, eliminating the need for additional gas-liquid separation cavities or components. This results in a compact and highly integrated device that meets the packaging requirements of high-power-density devices, broadening its application scenarios. Stable gas-liquid separation flow avoids system oscillations and pressure fluctuations, reducing the impact and corrosion of the working fluid on the channel walls. Continuous liquid working fluid replenishment ensures that the heat exchange surface remains constantly wetted, preventing device damage caused by localized overheating and extending the device's lifespan and operational reliability.

[0026] Please continue reading Figures 1 to 4 ,in, Figure 3 , Figure 4 Solid arrows represent liquid flow paths, while cross-sectional arrows represent gas / two-phase flow paths.

[0027] The phase change heat dissipation device provided in this embodiment of the invention achieves stable gas-liquid separation and efficient phase change heat dissipation through the synergistic design of multi-stage flow channels and microchannels.

[0028] The sealed housing 100 is a closed cavity structure made of material with good sealing and thermal conductivity. It is used to house the microchannel phase change heat transfer structure and multi-stage flow channel structure, isolating it from the external environment and preventing working fluid leakage and impurity ingress. The working fluid inlet 102 is located on one side of the housing for introducing liquid working fluid; the working fluid outlet 104 is located on the other side or top of the housing for discharging gaseous working fluid. The overall dimensions of the housing are adapted to the layout of the microchannel and flow channel structure, ensuring a compact internal space and facilitating working fluid flow.

[0029] The microchannel phase change heat transfer structure consists of multiple parallel microchannels evenly distributed in the lower region within the sealed housing 100, corresponding to the heat source contact area. The cross-sectional shape of the microchannels is adapted to the phase change heat transfer requirements, with smooth inner walls and nucleation points to enhance the boiling effect of the working fluid. Multiple microchannels connected in parallel form a highly efficient heat transfer network, increasing the contact area between the working fluid and the wall surface and improving heat transfer efficiency. The flow direction of the microchannels is perpendicular to and intersects with the secondary liquid flow channel 108, forming a cross flow field, providing a structural basis for gas-liquid separation.

[0030] The main channel 106 is a long strip channel with one end directly connected to the working fluid inlet 102 and the other end extending in a divergent manner to evenly distribute the liquid working fluid to each secondary liquid channel 108. The inner wall of the channel is smooth to reduce flow resistance.

[0031] The secondary liquid flow channel 108 consists of multiple parallel branch channels, horizontally positioned above the microchannel phase change heat transfer structure. One end is vertically connected to the main flow channel 106, and the other end faces the inlet area of ​​the microchannel. The outlet is aligned with the microchannel, ensuring that the liquid working fluid can be smoothly introduced into each microchannel.

[0032] The secondary gas / two-phase flow channel 110 is located above the secondary liquid flow channel 108. It is also a parallel branch channel. One end is connected to the outlet area of ​​the microchannel phase change heat exchange structure, and the other end is connected to the working fluid outlet 104 after convergence. It is used to quickly gather and export the gas phase working fluid. The channel cross-sectional size is larger than that of the secondary liquid flow channel 108 to reduce the gas phase flow resistance.

[0033] Liquid working fluid enters the main flow channel 106 through working fluid inlet 102, and after being split, is vertically introduced into the microchannel through secondary liquid flow channel 108. Within the microchannel, the working fluid contacts the wall surface, absorbs heat, and undergoes a phase change to generate a gaseous working fluid. Because the microchannel and secondary liquid flow channel 108 are perpendicularly intersecting, the gas and liquid working fluids naturally stratify under the influence of the cross-flow field: the liquid working fluid continues to flow along the bottom of the microchannel and replenishes the heat exchange surface, while the gaseous working fluid rises and enters the secondary gas / two-phase flow channel 110, finally exiting through working fluid outlet 104. The entire process requires no additional separation device; the gas-liquid separation flow is achieved through structural design.

[0034] According to one embodiment of the present invention, the sealing housing 100 includes an upper cover plate and a lower substrate plate, the lower substrate plate being used to contact a heat source, and a microchannel phase change heat transfer structure being disposed within the lower substrate plate.

[0035] In one embodiment of the present invention, the lower substrate is a rigid flat plate structure made of a high thermal conductivity material, with a smooth and flat bottom surface for close contact with the heat source, ensuring efficient heat conduction. Multiple parallel microchannels are machined inside the lower substrate, forming a microchannel phase-change heat transfer structure. The size and density of the microchannels are adapted to the high heat flux density heat dissipation requirements. The thickness of the substrate is optimized to ensure structural strength while rapidly transferring heat from the heat source to the working fluid within the microchannels, preventing heat accumulation.

[0036] The upper cover plate has a cavity structure that precisely matches the dimensions of the lower substrate, forming a sealed space through a sealing structure. The inner side of the upper cover plate has a pre-reserved flow channel forming area for constructing a multi-stage flow channel structure. Its material is the same as the lower substrate or a suitable high thermal conductivity material is selected to ensure balanced overall heat conduction performance. The thickness of the cover plate is designed according to the flow channel depth and structural strength to prevent deformation from affecting the flow channel sealing performance.

[0037] The microchannel phase change heat transfer structure of the lower substrate is precisely aligned with the multi-stage flow channel structure of the upper cover plate. The outlet of the secondary liquid flow channel 108 faces the inlet of the microchannel, and the inlet of the secondary gas / two-phase flow channel 110 covers the outlet area of ​​the microchannel, ensuring smooth flow of the working fluid. After closure, a sealed working fluid flow space is formed between the upper cover plate and the lower substrate, eliminating the risk of leakage and providing a structural basis for gas-liquid separation flow.

[0038] The bottom surface of the lower substrate is connected to the heat source via a thermally conductive medium or directly. The heat generated by the heat source is rapidly conducted to the walls of the microchannels, and then transferred to the internal working fluid, triggering a phase change heat transfer. The upper cover plate assists in heat dissipation through heat conduction, preventing its own temperature from becoming too high and affecting the working fluid state within the flow channel, thus ensuring the thermal management efficiency of the entire device.

[0039] According to one embodiment of the present invention, a main flow channel 106, a secondary liquid flow channel 108, and a secondary gas / two-phase flow channel 110 are formed within the upper cover plate.

[0040] In one embodiment of the present invention, the main channel 106 is an elongated channel formed within the upper cover plate, with one end directly connected to the working fluid inlet 102 and the other end extending into the interior of the cover plate, distributed in a divergent pattern. The cross-sectional dimensions of the main channel 106 are designed according to the working fluid flow rate to ensure that the working fluid can be quickly and evenly distributed to the secondary channels. The inner wall of the channel is smooth to reduce flow resistance. The orientation of the main channel 106 is adapted to the distribution position of the secondary channels, making the working fluid distribution more balanced.

[0041] The secondary liquid channels 108 consist of multiple parallel branch channels, one end of which is perpendicularly connected to the main channel 106, and the other end faces the microchannel phase change heat exchange structure, with the outlet aligned with the inlet region of the microchannel. The cross-sectional shape of the channels is rectangular or trapezoidal, and the dimensions are adapted to the inlet size of the microchannel to ensure smooth introduction of the working fluid into the microchannel. Multiple secondary liquid channels 108 are evenly distributed on one side of the main channel 106 to achieve uniform distribution of the working fluid, ensuring that each microchannel receives sufficient liquid working fluid.

[0042] The secondary gas / two-phase flow channel 110 is positioned above the secondary liquid flow channel 108 and is a parallel branch channel. One end connects to the outlet region of the microchannel phase change heat exchange structure, and the other end converges and connects to the working fluid outlet 104. The cross-sectional dimension of the flow channel is larger than that of the secondary liquid flow channel 108, facilitating rapid collection and discharge of the gaseous working fluid. The inner wall of the channel is smooth to reduce resistance during gaseous working fluid flow. The flow channel's orientation avoids the secondary liquid flow channel 108, forming a layered flow channel layout to prevent mutual interference between the gas and liquid working fluids.

[0043] All flow channels are integrally molded into the upper cover plate using precision machining. The thickness of the partitions between the flow channels has been optimized to ensure structural strength while avoiding obstruction of heat conduction. The inlet and outlet of the flow channels are precisely aligned with their corresponding interfaces, forming a sealed flow channel system with the lower substrate after closure, eliminating the risk of working fluid leakage.

[0044] According to one embodiment of the present invention, the upper cover plate and the lower substrate are assembled by brazing, diffusion welding or sealing bolts.

[0045] In one embodiment of the present invention, when using a brazing process, brazing filler metal is evenly applied to the mating surfaces of the upper cover plate and the lower substrate. After the two are precisely aligned, they are placed in a high-temperature furnace for heating. During the heating process, the brazing filler metal melts and fills the tiny gaps in the mating surfaces. After cooling, a strong metallurgical bond is formed, achieving a sealed connection between the upper cover plate and the lower substrate. The brazing mating surfaces are pretreated to remove oxide layers and impurities, ensuring brazing quality and avoiding incomplete or missed welds.

[0046] During diffusion welding assembly, the mating surfaces of the upper cover plate and the lower substrate are ground smooth and cleaned. After alignment, a certain pressure is applied and maintained at a high temperature for a period of time. Through atomic diffusion, a strong bonding layer is formed at the mating surfaces, achieving a sealed fixation between the two. The temperature, pressure, and holding time of diffusion welding are optimized according to material properties to ensure connection strength and sealing performance, while avoiding damage to the microchannel and flow channel structure caused by high temperatures.

[0047] During the assembly of the sealing bolts, sealing washers are placed on the mating surfaces of the upper cover plate and the lower base plate. Bolts are then tightened by passing them through pre-drilled bolt holes on both surfaces. The bolts are evenly distributed along the edges of the mating surfaces to ensure uniform tightening force, resulting in a tight fit. The compressed sealing washers form a sealing barrier, preventing leakage of the working fluid. The number and specifications of the bolts are designed according to the dimensions of the device and the sealing requirements to ensure structural stability and sealing performance after assembly.

[0048] Regardless of the assembly method used, an airtightness test must be performed after assembly. This is done by injecting pressurized gas into the sealed housing 100 to check for leaks. The assembled device ensures that the flow channels of the upper cover plate and the microchannels of the lower substrate are precisely aligned, without misalignment or blockage, to guarantee smooth flow of the working fluid.

[0049] According to one embodiment of the present invention, the upper cover plate and the lower substrate are integrally formed by metal 3D printing technology.

[0050] In one embodiment of the present invention, a high thermal conductivity metal or composite material is selected as the printing material. The particle size and purity of the material powder are screened to ensure printing quality and thermal conductivity. Before printing, the device is sliced ​​according to its three-dimensional model, and reasonable printing parameters are set, including printing layer height, laser power, scanning speed, etc., to ensure that fine structures such as flow channels and microchannels can be accurately formed.

[0051] Using metal 3D printing technology, the lower substrate, microchannel phase change heat transfer structure, upper cover plate, and internal multi-level flow channel structure are printed layer by layer from bottom to top, forming the entire device as a single piece without any seams. During the printing process, the internal structure of the flow channels and microchannels is formed with the assistance of support material. After printing, the support material is removed to ensure that the flow channels and microchannels remain unobstructed.

[0052] To address the precise dimensions of the microchannels and flow channels, printing parameters are optimized to ensure that the cross-sectional dimensions, length, and connection angles of the flow channels accurately meet design requirements. During the printing process, the forming quality is monitored in real time, and parameters are adjusted promptly to prevent issues such as flow channel blockage and dimensional deviations. The one-piece molding structure ensures a smooth transition between the flow channels and microchannels, without steps or gaps, facilitating the smooth flow of the working fluid.

[0053] After printing, the device undergoes heat treatment to eliminate internal stress and improve structural strength and thermal conductivity. The sealing surfaces are precision machined to ensure the device's airtightness. Testing equipment verifies the dimensional accuracy and unobstructed flow of the flow channels and microchannels to ensure that heat dissipation performance meets design requirements.

[0054] According to one embodiment of the invention, the cross-section of the microchannel is arranged asymmetrically along its flow direction to form a pressure gradient for inducing gas-liquid partitioning.

[0055] In one embodiment of the invention, the microchannel has a trapezoidal, inverted trapezoidal, or irregular cross-sectional shape, exhibiting an asymmetrical distribution along the flow channel direction. For example, in an inverted trapezoidal cross-section microchannel, one wall is vertical while the other is inclined; or in a trapezoidal cross-section microchannel, the inclination angles of the two walls are different. This asymmetrical cross-sectional design creates a pressure gradient along the flow channel direction within the microchannel, with the pressure on the side closer to the inclined wall being lower than on the other side.

[0056] The asymmetric cross-sectional structure alters the flow field distribution within the microchannel. As the liquid working fluid flows within the microchannel, velocity differences arise along different regions of the asymmetric cross-section, resulting in a pressure gradient. The pressure is higher near the bottom of the microchannel, propelling the liquid working fluid along the bottom; the pressure is lower near the top, facilitating the upward accumulation and flow of the gaseous working fluid, thus achieving natural gas-liquid zoning.

[0057] Multiple microchannels with asymmetrical cross-sections are arranged in parallel to form a microchannel phase change heat transfer structure. The length of the microchannels is adapted to the size of the device, and the flow direction is perpendicular to and staggered with the flow direction of the secondary liquid flow channel 108. The inlet of the microchannel is precisely connected to the outlet of the secondary liquid flow channel 108, and the outlet is connected to the inlet of the secondary gas / two-phase flow channel 110, allowing the gas-liquid working fluid guided by the pressure gradient to be smoothly introduced and discharged.

[0058] The dimensions of the asymmetric cross-section are optimized, and the angle of the inclined wall, the height and width of the cross-section are adapted to the physical properties and flow requirements of the working fluid, ensuring that the pressure gradient formed is sufficient to induce gas-liquid partitioning, while avoiding excessive flow resistance due to unreasonable cross-sectional dimensions.

[0059] According to one embodiment of the present invention, the liquid working fluid enters the microchannel phase change heat transfer structure via the working fluid inlet 102, the main flow channel 106, and the secondary liquid flow channel 108. The gaseous working fluid flows out of the working fluid outlet 104 through the microchannel phase change heat transfer structure and the secondary gas / two-phase flow channel 110.

[0060] In one embodiment of the present invention, after the liquid working fluid enters the sealed housing 100 through the working fluid inlet 102, it first flows into the main channel 106, where initial diversion is achieved. Subsequently, the working fluid is further distributed through multiple secondary liquid channels 108, the outlets of which are aligned with the inlets of the microchannel phase change heat transfer structure, allowing the liquid working fluid to be smoothly introduced into each microchannel. During the flow, the liquid working fluid flows along the bottom of the microchannel under pressure, making full contact with the microchannel wall and absorbing heat.

[0061] The liquid working fluid absorbs heat within the microchannel and undergoes a phase change, generating a gaseous working fluid. Under the influence of pressure gradient and buoyancy, the gaseous working fluid flows upward along the top of the microchannel and converges to the outlet region of the microchannel. Subsequently, the gaseous working fluid enters the secondary gas / two-phase flow channel 110. Multiple secondary gas / two-phase flow channels 110 collect the gaseous working fluid and guide it into the working fluid outlet 104, finally discharging it from the sealed housing 100.

[0062] The liquid and gaseous working fluids flow in separate, tiered layers, forming a parallel flow network. The secondary liquid flow channel 108 precisely connects to the inlet of the microchannel, and the secondary gas / two-phase flow channel 110 precisely connects to the outlet of the microchannel, ensuring smooth flow of the working fluid without stagnation or blockage. The length and cross-sectional dimensions of the flow paths are adapted to the flow characteristics of the working fluid, ensuring rapid introduction of the liquid working fluid and rapid discharge of the gaseous working fluid.

[0063] The entire flow path is located within the sealed housing 100, and the connections of the flow channels are well-sealed, eliminating the risk of working fluid leakage. The smooth inner wall of the flow channel reduces resistance and wear during working fluid flow, extending the service life of the device.

[0064] According to one embodiment of the present invention, the working fluid outlet 104 is positioned higher than the microchannel phase change heat transfer structure to utilize the gravity effect to assist in the discharge of the gaseous working fluid.

[0065] In one embodiment of the invention, the working fluid outlet 104 is located above the top or side of the upper cover plate of the sealing housing 100, with its lowest edge higher than the highest edge of the microchannel phase change heat transfer structure. The location of the outlet corresponds to the confluence area of ​​the secondary gas / two-phase flow channel 110, ensuring smooth introduction of the gaseous working fluid into the outlet. The cross-sectional shape of the outlet is circular or rectangular, and its size is adapted to the discharge flow rate of the gaseous working fluid, ensuring rapid discharge of the gaseous working fluid.

[0066] The density of the gaseous working fluid is less than that of the liquid working fluid, and it tends to float upwards under the influence of gravity. The design of the working fluid outlet 104 being higher than the microchannel makes it easier for the gaseous working fluid to flow upwards and converge at the working fluid outlet 104 under the influence of its own buoyancy and the difference in gravity, thus accelerating the discharge of the gaseous working fluid and preventing it from stagnating above the microchannel.

[0067] The secondary gas / two-phase flow channel 110 extends upward from the outlet region of the microchannel to the working fluid outlet 104, forming an upward flow path. This, in conjunction with the gravity effect, further assists in the discharge of the gaseous working fluid. The inclination angle of the flow channel is adapted to the direction of gravity, reducing the resistance to the flow of the gaseous working fluid and allowing it to rise smoothly to the working fluid outlet 104.

[0068] The working fluid outlet 104 is sealed to the external pipeline to prevent working fluid leakage and air ingress. The edges of the outlet are smoothed to reduce resistance to the flow of the gaseous working fluid and prevent blockage caused by working fluid residue. According to one embodiment of the present invention, the cross-sectional shape of the microchannel is rectangular, trapezoidal, or inverted trapezoidal.

[0069] In one embodiment of the present invention, the microchannel with a rectangular cross-section has four planar walls that are parallel to each other. The height and width of the cross-section are adapted to the flow and phase change requirements of the working fluid. The inner wall of the channel is smooth, and the bottom wall is in close contact with the heat source contact area of ​​the lower substrate, ensuring efficient heat conduction. The microchannel with a rectangular cross-section is simple to manufacture, its dimensional accuracy is easy to control, and multiple channels arranged in parallel form a uniform heat exchange network.

[0070] The microchannel has a trapezoidal cross-section with inclined side walls, and the bottom width is greater than the top width. The inclined side walls guide the upward flow of the gaseous working fluid, facilitating the detachment of bubbles from the bottom wall and their upward aggregation. The wider bottom design increases the contact area between the liquid working fluid and the wall, improving heat exchange efficiency; the narrower top design promotes rapid aggregation of the gaseous working fluid.

[0071] The microchannel features an inverted trapezoidal cross-section with sloping side walls and a wider top than bottom. This structure creates a more spacious area at the top of the microchannel, facilitating rapid collection and discharge of the gaseous working fluid and reducing flow resistance. The narrower bottom allows the liquid working fluid to quickly form a stable flow layer, ensuring continuous wetting of the bottom wall, while the sloping side walls also aid in bubble detachment.

[0072] Regardless of the cross-sectional shape, the microchannels are arranged in parallel to form a microchannel phase change heat transfer structure, with the flow direction perpendicular to and staggered with the secondary liquid flow channel 108. The inlet of the microchannel is precisely connected to the outlet of the secondary liquid flow channel 108, and the outlet is connected to the inlet of the secondary gas / two-phase flow channel 110. The cross-sectional dimensions are adapted to the inlet and outlet dimensions of the flow channel to ensure smooth flow of the working fluid.

[0073] According to one embodiment of the present invention, the device is made of a high thermal conductivity metal or composite material, wherein the high thermal conductivity metal or composite material is selected from at least one of copper, aluminum, titanium alloy, graphite-reinforced composite metal or diamond composite metal.

[0074] In one embodiment of the present invention, the selected high thermal conductivity metals include copper, aluminum, and titanium alloys, and the composite materials include graphite-reinforced composite metals and diamond composite metals. These materials have extremely high thermal conductivity, enabling them to quickly transfer heat generated by the heat source and preventing heat accumulation inside the device. The materials also possess good mechanical strength and corrosion resistance, allowing them to withstand corrosion from the working fluid and stress caused by temperature changes, thus meeting the requirements for long-term use.

[0075] The sealed housing 100, microchannel phase change heat transfer structure, and multi-stage flow channel structure of the entire device are all made of the aforementioned materials to ensure efficient heat conduction between the various components of the device. As the main component in contact with the heat source, the lower substrate is preferably made of materials with the highest thermal conductivity, such as copper or diamond composite metal, to ensure rapid heat transfer; the upper cover and flow channel structure can be made of suitable materials according to requirements to balance thermal conductivity and cost.

[0076] The selected materials all possess excellent machinability and can be processed into various shapes using CNC milling, etching, brazing, 3D printing, and other techniques, enabling the precise fabrication of intricate structures such as microchannels and multi-level flow channels. The thermal expansion coefficients of the materials are matched to prevent structural deformation or sealing failure caused by excessive differences in thermal expansion coefficients between different components.

[0077] The material has good compatibility with the working medium, will not react chemically with the working medium, and will not experience performance degradation due to immersion in the working medium, ensuring the reliability and safety of the device during long-term operation.

[0078] 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: The sealed housing (100) is provided with a working fluid inlet (102) and a working fluid outlet (104). A microchannel phase change heat transfer structure is disposed within the sealed housing (100), and the microchannel phase change heat transfer structure includes multiple parallel microchannels; A multi-stage flow channel structure is disposed within the sealed housing (100). The multi-stage flow channel structure includes a main flow channel (106), at least one secondary liquid flow channel (108), and at least one secondary gas / two-phase flow channel (110). The main channel (106) is connected to the working fluid inlet (102); At least one of the secondary liquid channels (108) is disposed above the microchannel phase change heat exchange structure and is in fluid communication with the main channel (106) and the microchannel phase change heat exchange structure. At least one of the secondary liquid channels (108) is used to introduce liquid working fluid into the microchannel. The flow direction of the microchannel is perpendicular to the flow direction of the secondary liquid channel (108). At least one of the secondary gas / two-phase flow channels (110) is disposed above the secondary liquid flow channel (108) and is in fluid communication with the microchannel phase change heat transfer structure and the working fluid outlet (104) for collecting and exporting the gaseous working fluid generated in the microchannel.

2. The phase change heat dissipation device according to claim 1, characterized in that, The sealed housing (100) includes an upper cover plate and a lower substrate plate, the lower substrate plate being used to contact a heat source, and the microchannel phase change heat transfer structure being disposed within the lower substrate plate.

3. The phase change heat dissipation device according to claim 2, characterized in that, The main flow channel (106), the secondary liquid flow channel (108), and the secondary gas / two-phase flow channel (110) are formed within the upper cover plate.

4. The phase change heat dissipation device according to claim 2, characterized in that, The upper cover plate and the lower substrate are assembled by brazing, diffusion welding or sealing bolts.

5. The phase change heat dissipation device according to claim 2, characterized in that, The upper cover and the lower substrate are integrally formed using metal 3D printing technology.

6. The phase change heat dissipation device according to claim 1, characterized in that, The cross-sections of the microchannels are arranged asymmetrically along their flow direction to form a pressure gradient for inducing gas-liquid partitioning.

7. The phase change heat dissipation device according to claim 1, characterized in that, The liquid working fluid enters the microchannel phase change heat transfer structure via the working fluid inlet (102), the main flow channel (106), and the secondary liquid flow channel (108); The gaseous working fluid flows out of the working fluid outlet (104) via the microchannel phase change heat transfer structure and the secondary gas / two-phase flow channel (110).

8. The phase change heat dissipation device according to claim 1, characterized in that, The working fluid outlet (104) is positioned higher than the microchannel phase change heat transfer structure to utilize the gravity effect to assist in the discharge of the gaseous working fluid.

9. The phase change heat dissipation device according to any one of claims 1 to 8, characterized in that, The cross-sectional shape of the microchannel is rectangular, trapezoidal, or inverted trapezoidal.

10. The phase change heat dissipation device according to any one of claims 1 to 8, characterized in that, The device is made of a high thermal conductivity metal or composite material, wherein the high thermal conductivity metal or composite material is selected from at least one of copper, aluminum, titanium alloy, graphite-reinforced composite metal or diamond composite metal.

Images