Surface structure for enhanced boiling heat transfer, and manufacturing method therefor

Abstract

The present application discloses a surface structure for enhanced boiling heat transfer, comprising first channels for vapor bubble departure, micro-scale structures for promoting vapor bubble nucleation, and second channels for liquid suction. The aperture of the first channels is greater than the aperture of the second channels, the aperture of the second channels is greater than the width of the micro-scale structures, and there are a plurality of first channels, micro-scale structures, and second channels. In the surface structure for enhanced boiling heat transfer disclosed in the present application, the provision of the plurality of micro-scale structures can increase effective vapor bubble nucleation sites for boiling, thereby promoting the start of boiling. The provision of the plurality of first channels can provide low-resistance vapor flow channels, so that vapor bubbles can depart more quickly. The departure direction of vapor bubbles is consistent with the heat dissipation direction, thereby improving the heat transfer efficiency. The provision of the plurality of first channels separates vapor and liquid flows, minimizing interference between vapor bubble departure and liquid suction, thereby enhancing the heat transfer performance. The present application further discloses a method for manufacturing the surface structure for enhanced boiling heat transfer.

Description

Surface structure for enhancing boiling heat transfer and preparation method thereof

[0001] The present application relates to the technical field of heat transfer, and more particularly to a surface structure for enhancing boiling heat transfer and a preparation method thereof.

[0002] With the development of integration and miniaturization of electronic components, many high-power energy systems, such as radars, lasers, light-emitting diodes and microprocessors, need to dissipate huge heat in limited space. Compared with single-phase liquid convection cooling methods (such as fans), vapor / liquid phase change cooling methods (such as capillary evaporation and boiling) make full use of the huge latent heat of vapor / liquid phase change, and can achieve efficient heat dissipation at low surface temperature, so they are paid more and more attention in the design of heat dissipation systems.

[0003] The critical heat flux (CHF) of capillary evaporation is mainly improved by thickening the liquid film to improve the liquid transport capacity of the surface. However, increasing the thickness of the capillary core will significantly increase the thermal resistance of the surface, thereby reducing the heat transfer coefficient (HTC) of the surface. In recent years, by introducing vapor bubbles in the thick liquid film, liquid film boiling can significantly expand the vapor-liquid evaporation interface and improve the heat transfer coefficient, solving the contradictory demand of surface structure thickness on the improvement of critical heat flux and heat transfer coefficient. To improve the performance of vapor / liquid phase change heat transfer, some scholars have developed surface structures with high capillary pumping performance. However, these surface structures only perform outstandingly in strengthening liquid film transport.

[0004] Therefore, how to prepare a surface structure to realize the synergistic enhancement of liquid film transport and vapor bubble detachment, and improve the heat transfer efficiency and heat transfer performance of boiling, has become a technical problem to be solved by those skilled in the art.

[0005]

Content of application

[0006] Therefore, the core of the present application is to provide a surface structure for enhancing boiling heat transfer to realize the synergistic enhancement of liquid film transport, vapor bubble nucleation and vapor bubble detachment, and improve the heat transfer efficiency and heat transfer performance of boiling.

[0007] Another core of the present application is to provide a preparation method of the surface structure for enhancing boiling heat transfer.

[0008] To achieve the above purpose, the present application provides the following technical solutions:

[0009] A surface structure for enhancing boiling heat transfer, which is combined on a heat transfer substrate and has a first pore for vapor bubble detachment, a micro-scale structure for promoting vapor bubble nucleation and a second pore for liquid pumping;

[0010] ​​The first hole channel has a larger pore size than the second hole channel, and the second hole channel has a larger pore size than the width of the micro-scale structure.

[0011] The first hole channel, the micro-scale structure, and the second hole channel are each a plurality.

[0012] Optionally, in the surface structure for enhanced boiling heat transfer, the arrangement of the plurality of first hole channels includes at least one of an array arrangement or a random arrangement.

[0013] The array arrangement includes at least one of a square array, a rectangular array, a ring array, and a hexagonal array.

[0014] Optionally, in the surface structure for enhanced boiling heat transfer, the cross-sectional shape of the first hole channel includes at least one of a triangle, a rectangle, a rhombus, a pentagon, a hexagon, a circle, an ellipse, and a star; and / or,

[0015] The type of the micro-scale structure includes at least one of a cavity, a micro-hole, and a crack.

[0016] Optionally, in the surface structure for enhanced boiling heat transfer, the first hole channel is configured as a blind hole channel on the surface structure for enhanced boiling heat transfer; or,

[0017] The first hole channel is configured as a through-hole channel on the surface structure for enhanced boiling heat transfer; or,

[0018] Some of the first hole channels are configured as blind hole channels on the surface structure for enhanced boiling heat transfer, and the remaining first hole channels are configured as through-hole channels on the surface structure for enhanced boiling heat transfer.

[0019] Optionally, in the surface structure for enhanced boiling heat transfer, the first hole channel includes at least one of a gradually expanding hole channel, a gradually shrinking hole channel, and a uniform hole channel.

[0020] Optionally, in the surface structure for enhanced boiling heat transfer, the pore size of the first hole channel is 10 μm-1000 μm, and the spacing between adjacent two first hole channels is 15 μm-5000 μm; and / or,

[0021] The height of the micro-scale structure is 0.1 μm-20 μm, and the aspect ratio is greater than 2.

[0022] Optionally, in the surface structure for enhanced boiling heat transfer, the pore size of the second hole channel is 10 μm-500 μm, and the diameter or width of the skeleton of the surface structure for enhanced boiling heat transfer is 20 μm-100 μm.

[0023] Optionally, in the surface structure for enhanced boiling heat transfer, the surface structure for enhanced boiling heat transfer includes one or more of a multi-layer woven mesh, a sintered powder, a foamed metal, a groove, a micro-column array, and an electrodeposited porous structure.

[0024] Optionally, in the surface structure for enhancing boiling heat transfer, the material for preparing the surface structure for enhancing boiling heat transfer comprises one or more of red copper, brass, bronze, aluminum, silicon, titanium, and stainless steel; and / or,

[0025] The material for preparing the heat transfer substrate comprises one of red copper, brass, bronze, aluminum, silicon, titanium, and stainless steel.

[0026] A method for preparing a surface structure for enhancing boiling heat transfer, for preparing the surface structure for enhancing boiling heat transfer as described above, comprising:

[0027] Preparing a uniform surface structure, the uniform surface structure comprising second holes;

[0028] Preparing first holes, perforating the uniform surface structure to form a first surface structure with the first holes;

[0029] Combining the first surface structure to the heat transfer substrate to form a combination of the two;

[0030] Preparing micro-scale structures, using an etching method to treat the surface of the combination of the heat transfer substrate and the first surface structure to form a plurality of micro-scale structures on the first surface structure and the heat transfer substrate;

[0031] Performing a hydrophilic or hydrophobic surface modification treatment on at least a portion of the micro-scale structures.

[0032] Optionally, in the method for preparing the surface structure for enhancing boiling heat transfer, the method further comprises a pretreatment step before the step of combining the first surface structure to the heat transfer substrate, the pretreatment step specifically comprising:

[0033] Grinding the surface of the heat transfer substrate;

[0034] Cleaning the heat transfer substrate and the first surface structure after grinding.

[0035] Optionally, in the method for preparing the surface structure for enhancing boiling heat transfer, the etching method comprises at least one of chemical etching, sandblasting, electroplating, and mechanical processing.

[0036] Optionally, in the method for preparing the surface structure for enhancing boiling heat transfer, the method for hydrophilic or hydrophobic surface modification treatment comprises at least one of plasma modification, surface coating modification, and surface grafting modification.

[0037] From the above technical solutions can be seen, the surface structure of the enhanced boiling heat transfer disclosed by the application, the second hole is arranged for pumping liquid, the plurality of micro-scale structures are arranged to increase the effective vapor bubble nucleation sites of boiling and promote the initiation of boiling. The plurality of first holes are arranged to provide a low-resistance vapor flow channel, so that the vapor bubbles can be detached more quickly. The detachment direction of the vapor bubbles is consistent with the heat dissipation direction, which can improve the heat transfer efficiency. The plurality of first holes separate the vapor-liquid flow, minimize the interference between the vapor bubble detachment and the liquid pumping, and thus enhance the heat transfer performance.

[0038] The preparation method of the surface structure of the enhanced boiling heat transfer disclosed by the application is simple in steps, reasonable in design, easy to implement, strong in operability, convenient for large-scale production and preparation, and has important practical value and popularization significance.

DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0040] Fig. 1 is a schematic diagram of a liquid film boiling of the surface structure of the enhanced boiling heat transfer disclosed by the embodiments of the application;

[0041] Fig. 2 is a top view and a side view SEM image of a perforated micro-copper mesh structure with a square array of the array arrangement of the first holes and a SEM image of a micro-hole structure on a copper wire disclosed by the embodiments of the application;

[0042] Fig. 3 is a top view SEM image of a perforated micro-copper mesh structure with a hexagonal array of the array arrangement of the first holes and a schematic diagram of a hexagonal array disclosed by the embodiments of the application;

[0043] Fig. 4 is a top view SEM image of a perforated micro-copper powder structure with a square array of the array arrangement of the first holes disclosed by the embodiments of the application;

[0044] Fig. 5 is a top view SEM image of a perforated foam copper structure with a square array of the array arrangement of the first holes disclosed by the embodiments of the application;

[0045] Fig. 6A is a field diagram of a liquid film boiling experimental device disclosed by the embodiments of the application;

[0046] Fig. 6B is a schematic diagram of a liquid film boiling experimental device disclosed by the embodiments of the application;

[0047] Fig. 6C is a schematic diagram of the position of a thermocouple inside a heating block in a liquid film boiling experimental device disclosed by the embodiments of the application;

[0048] FIG. 7A is an optical photograph of the device for measuring the thickness-direction permeability of the surface structure for enhanced boiling heat transfer according to the embodiments of the present application;

[0049] FIG. 7B is a curve of the thickness-direction viscous pressure drop of water flow through the perforated micro-copper mesh with different perforation distances versus the water flow velocity according to the embodiments of the present application;

[0050] FIG. 7C is a curve of the thickness-direction viscous pressure drop of water flow through the micro-copper mesh with different kinds of uniform surface structures versus the water flow velocity according to the embodiments of the present application;

[0051] FIG. 7D is a curve of the thickness-direction viscous pressure drop of water flow through the perforated surface structure versus the water flow velocity according to the embodiments of the present application;

[0052] FIG. 8A is a measurement result of the thickness-direction permeability of the perforated micro-copper mesh with different perforation distances according to the embodiments of the present application;

[0053] FIG. 8B is a measurement result of the thickness-direction permeability of the surface of the different uniform surface structures and the perforated surface structure according to the embodiments of the present application;

[0054] FIG. 9A is a line graph of the liquid film boiling heat flux density on the perforated micro-copper mesh with the array arrangement mode of the first hole channel being a square array according to the embodiments of the present application;

[0055] FIG. 9B is a measurement result graph of the liquid film boiling critical heat flux density and the maximum heat exchange coefficient on the perforated micro-copper mesh with the array arrangement mode of the first hole channel being a square array and a hexagonal array according to the embodiments of the present application;

[0056] FIG. 10A is an optical photograph of two time-lapse photographs of the liquid film boiling on the perforated micro-copper mesh surface with the array arrangement mode of the first hole channel being a hexagonal array and the corresponding schematic diagram of bubble dynamics according to the embodiments of the present application;

[0057] FIG. 10B is an optical photograph of two time-lapse photographs of the liquid film boiling on the perforated micro-copper mesh surface with the array arrangement mode of the first hole channel being a square array and the corresponding schematic diagram of bubble dynamics according to the embodiments of the present application;

[0058] FIG. 11A is an optical photograph of three time-lapse photographs of the liquid film boiling on the uniform micro-copper mesh surface and the corresponding schematic diagram of bubble dynamics according to the embodiments of the present application;

[0059] FIG. 11B is an optical photograph of three time-lapse photographs of the liquid film boiling on the perforated micro-copper mesh surface with the perforation pitch being 1500 μm and the corresponding schematic diagram of bubble dynamics according to the embodiments of the present application;

[0060] Figure 11C is three time-lapse optical photographs of liquid film boiling on the perforated micro-copper mesh surface with a perforation pitch of 900 μm and the corresponding schematic of bubble dynamics according to the embodiments disclosed herein;

[0061] Figure 12A is a quantitative analysis of the liquid film boiling area on three test surface structures as a function of heat flux according to the embodiments disclosed herein;

[0062] Figure 12B is a quantitative analysis of the bubble departure frequency on three test surface structures as a function of heat flux according to the embodiments disclosed herein;

[0063] Figure 13 is a comparison of the liquid film boiling heat transfer performance on three test surface structures according to the embodiments disclosed herein;

[0064] Figure 14 is a comparison of the liquid film boiling heat transfer performance of ordinary copper mesh, uniform micro-copper mesh and perforated micro-copper mesh with different heating areas according to the embodiments disclosed herein;

[0065] Figure 15 is a flow chart of a method for preparing a surface structure for enhanced boiling heat transfer according to the embodiments disclosed herein.

[0066] wherein 10 is a heater, A is a bubble;

[0067] 101 is a first hole, 102 is a micro-scale structure, 103 is a second hole, and 110 is a heat transfer substrate;

[0068] 210 is a liquid film boiling cavity, 211 is an observation window, 220 is a high-speed camera, 230 is a cooling circulation loop, 231 is a condenser, 232 is a refrigerator, 240 is a heating module, 241 is a direct current power supply, 242 is a cylindrical heater, 243 is a heating block, 244 is a thermal insulation material, 250 is a data measurement module, 251 is a thermocouple, 252 is a pressure transmitter, 253 is a data acquisition instrument, and 260 is a vacuum pump.

DETAILED DESCRIPTION

[0069] The core of the present application is to disclose a surface structure for enhanced boiling heat transfer to achieve synergistic enhancement of liquid film transport and bubble departure, and to improve the heat transfer efficiency and heat transfer performance of boiling.

[0070] Another core of the present application is to disclose a method for preparing the above-mentioned surface structure for enhanced boiling heat transfer.

[0071] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0072] As shown in FIG. 1, the present application discloses a surface structure for enhancing boiling heat transfer, which is combined on a heat transfer substrate 110 and has first holes 101 for bubble departure, micro-scale structures 102 for promoting bubble nucleation and second holes 103 for liquid extraction. It should be noted that the material of the surface structure for enhancing boiling heat transfer can be the same as or different from the material of the heat transfer substrate 110.

[0073] The number of the first holes 101, the micro-scale structures 102 and the second holes 103 is multiple, and they are arranged at intervals. Among them, the pore diameter of the first holes 101 > the pore diameter of the second holes 103 > the width of the micro-scale structures 102.

[0074] Taking the micro-copper mesh structure as an example, in order to distinguish the structure with the first holes 101 and the structure without the first holes 101, the micro-copper mesh structure with the first holes 101, the micro-scale structures 102 and the second holes 103 is called perforated micro-copper mesh, and the micro-copper mesh structure with only the second holes 103 is called uniform micro-copper mesh. The naming rules of other structures are the same. In the following, the perforated copper foam refers to the copper foam structure with the first holes 101, the micro-scale structures 102 and the second holes 103, the uniform copper foam refers to the copper foam structure with only the second holes 103, the perforated micro-copper powder refers to the micro-copper powder structure with the first holes 101, the micro-scale structures 102 and the second holes 103, and the uniform micro-copper powder refers to the micro-copper powder structure with only the second holes 103.

[0075] The uniform micro-copper mesh includes a multi-layer structure, and each single layer is composed of multiple copper wires. The second holes 103 refer to the holes formed by the pores between the copper wires and between the layers. The first holes 101 are formed by perforating the uniform micro-copper mesh, as shown in FIG. 1, the first holes 101 pass through the copper wires and the second holes 103. Multiple first holes 101 are arranged at intervals to form a low-resistance vapor flow channel for bubble departure.

[0076] The first holes 101 can be arranged uniformly, as shown in FIG. 2A, or non-uniformly. The cross-sectional shape of the first holes 101 includes at least one of a triangle, a rectangle, a rhombus, a pentagon, a hexagon, a circle, an ellipse, and a star, and can be other shapes. The micro-scale structures 102 are arranged on the skeleton of the surface structure for enhanced boiling heat transfer, as shown in FIGS. 2C and 2D. The micro-scale structures 102 shown in the figures are arranged on a copper wire, and FIG. 2D is a magnified view of the micro-scale structures 102 in FIG. 2C. The number in the lower right corner of the figure is a scale, which is only an example and cannot be used as a limitation. The type of the micro-scale structures 102 shown in the figure is a cavity, which can be circular, elliptical, or square, and the specific shape is not limited. The type of the micro-scale structures 102 can also be a micro-hole and a crack.

[0077] FIG. 1 illustrates liquid film boiling. The left picture shows a heater 10 that provides heat for boiling of the liquid. The surface structure for enhanced boiling heat transfer disclosed in the embodiments of the present application is arranged above the heater 10. The part without the heater 10 is a uniform surface structure with only the second holes 103. The liquid is supplied to the surface structure for enhanced boiling heat transfer disclosed in the embodiments of the present application through the second holes 103 (the arrow in the left picture indicates the flow direction of the liquid) to perform liquid film boiling and dissipate heat. As shown in the right picture of FIG. 1, the arrangement of the plurality of micro-scale structures 102 increases the effective bubble nucleation sites for boiling and promotes the initiation of liquid film boiling. The arrangement of the micro-scale structures 102 also improves the wettability of the surface, provides high capillary forces and low resistance permeable liquid channels, and allows liquid absorption to re-wet the heated surface. The arrangement of the plurality of first holes 101 provides low resistance vapor flow channels, which enable the bubbles to detach from the surface structure for enhanced boiling heat transfer quickly. As shown in the right picture of FIG. 1, the bubble A detaches from the first hole 101. The horizontal arrow in the right picture indicates liquid film suction, and the vertical arrow indicates the direction of the bubble A detachment. The direction of the bubble A detachment is consistent with the heat dissipation direction, which improves the heat transfer efficiency. The arrangement of the plurality of first holes 101 and the micro-scale structures 102 separates the vapor-liquid flow, minimizes the interference between bubble detachment and liquid suction, and thus enhances the overall heat transfer performance. It should be noted that the embodiments of the present application are applicable not only to liquid film boiling but also to other heat transfer application scenarios such as pool boiling, flow boiling, and spray cooling.

[0078] The surface structure for enhanced boiling heat transfer disclosed in the embodiments of the present application includes at least one of an array arrangement and a random arrangement. The array arrangement includes at least one of a square array, a rectangular array, a ring array, and a hexagonal array, and can be other array arrangements.

[0079] In some embodiments, the plurality of first holes 101 are arranged in an array, including a square array (as shown in FIG. 2A) and a hexagonal array (as shown in FIG. 3). In the following experiments, the array of the plurality of first holes 101 is of the square array and the hexagonal array.

[0080] The square array is shown in FIG. 2A, in which the array is 11x11, i.e., the array has 11 rows and 11 columns. For convenience of description, the plurality of first holes 101 arranged in the same line in the horizontal direction is referred to as a horizontal unit. The square array means that the first holes 101 at the corresponding positions of the plurality of horizontal units arranged in the vertical direction are in the same line. For each horizontal unit, the first holes 101 from left to right include eleven first holes 101. For all the horizontal units, the centers of the first holes 101 at the first, second, and eleventh positions are in the same line. The positions of the first holes 101 at other positions are the same as those of the first holes 101 at the first, second, and eleventh positions, which will not be described herein. It should be noted that the number of the first holes 101 shown in the figure is only an example, and the actual number can be selected according to the actual use scenario.

[0081] Based on the above embodiments, the hexagonal array means that the area where each first hole 101 is located is a regular hexagon, and the regular hexagons are connected in sequence, as shown in FIG. 3B. Alternatively, the hexagonal array means that the first holes 101 at the corresponding positions of the horizontal units in the odd-numbered rows are in the same line, and the first holes 101 at the corresponding positions of the horizontal units in the even-numbered rows are in the same line, as shown in FIG. 3A and FIG. 3B. Taking the first horizontal unit to the sixth horizontal unit as an example, the centers of the first holes 101 at the first, second, and fifth positions of the first, third, and fifth horizontal units are in the same line. The centers of the first holes 101 at the other positions are the same, which will not be described herein. The centers of the first holes 101 at the first, second, and sixth positions of the second, fourth, and sixth horizontal units are in the same line. The centers of the first holes 101 at the other positions are the same. It should be noted that the square array and the hexagonal array herein are only two specific schemes, and the array arrangement of the plurality of first holes 101 can also be other arrangements.

[0082] The surface structure for enhancing boiling heat transfer disclosed in the embodiments of the present application is configured as a blind hole channel in some specific embodiments; as a through hole channel in other specific embodiments; and as a blind hole channel for some first channels 101 and a through hole channel for the rest of the first channels 101 in other specific embodiments. As shown in Figure 2E, which is a side view of the first channel 101, the first channel 101 is configured as a through hole channel in the perforated micro-copper mesh, which includes a plurality of copper wires. As shown in the figure, the first channel 101 penetrates through the plurality of layers of copper wires (skeleton of the perforated micro-copper mesh) and the second channel 103. The first channel 101 is a through hole channel in the surface structure for enhancing boiling heat transfer. The blind hole channel refers to the first channel 101 penetrating through only some layers of copper wires and the second channel 103, but not all layers of copper wires.

[0083] The surface structure for enhancing boiling heat transfer disclosed in the embodiments of the present application is configured as a blind hole channel in some specific embodiments; as a through hole channel in other specific embodiments; and as a blind hole channel for some first channels 101 and a through hole channel for the rest of the first channels 101 in other specific embodiments. As shown in Figure 2E, which is a side view of the first channel 101, the first channel 101 is configured as a through hole channel in the perforated micro-copper mesh, which includes a plurality of copper wires. As shown in the figure, the first channel 101 penetrates through the plurality of layers of copper wires (skeleton of the perforated micro-copper mesh) and the second channel 103. The first channel 101 is a through hole channel in the surface structure for enhancing boiling heat transfer. The blind hole channel refers to the first channel 101 penetrating through only some layers of copper wires and the second channel 103, but not all layers of copper wires.

[0084] In some specific embodiments, the diameter of the first channel 101 is 10 μm-1000 μm (as shown in Figures 2B and 2E, d p ), the cross-sectional shape of the first channel 101 is circular, the distance between the adjacent two first channels 101 (hereinafter referred to as the hole spacing) is 15 μm-5000 μm, and the height of the micro-scale structure 102 is 0.1 μm-20 μm and the aspect ratio is greater than 2. As shown in Figure 2D, the type of the micro-scale structure 102 is a cavity. It should be noted that the distance between the adjacent two first channels 101 refers to the distance between the centers of the adjacent two first channels 101, as shown in Figure 2B, s p .

[0085] In some specific embodiments, the diameter of the first channel 101 is 10 μm-1000 μm (as shown in Figures 2B and 2E, d m , the cross-sectional shape of the first channel 101 is circular, the distance between the adjacent two first channels 101 (hereinafter referred to as the hole spacing) is 15 μm-5000 μm, and the height of the micro-scale structure 102 is 0.1 μm-20 μm and the aspect ratio is greater than 2. As shown in Figure 2D, the type of the micro-scale structure 102 is a cavity. It should be noted that the distance between the adjacent two first channels 101 refers to the distance between the centers of the adjacent two first channels 101, as shown in Figure 2B, s m(As shown in the drawing, taking the perforated micro copper mesh as an example), the drawing refers to the diameter range of the copper wire, if the surface structure for strengthening the boiling heat transfer is the perforated micro copper powder, it refers to the diameter range of the copper powder, and the drawing shown in Fig. 4 is a top SEM image of the perforated micro copper powder; if the surface structure for strengthening the boiling heat transfer is the perforated foam copper, it refers to the width range of the foam copper skeleton, and the drawing shown in Fig. 5 is a top SEM image of the perforated foam copper.

[0086] The surface structure for strengthening the boiling heat transfer disclosed in the embodiments of the present application is not limited to the multi-layer woven mesh, sintered powder and foam metal, but can also include other structure types such as grooves, micro column arrays, electrodeposited porous structures and combinations of these types.

[0087] Fig. 2 is a top SEM image of the perforated micro copper mesh, Fig. 4 is a top SEM image of the perforated micro copper powder structure, and Fig. 5 is a top SEM image of the perforated foam copper. The array arrangement of the first channels 101 of these structures is a square array, the aperture size of the first channels 101 is 300 μm, the inter-pore distance is 900 μm, the total thickness of the surface structure for strengthening the boiling heat transfer is 400 μm, and the width of the micro-scale structure 102 is 1 μm-10 μm. For the perforated micro copper mesh, the diameter of the copper wire of the copper mesh is 60 μm, the distance between the center lines of the copper wires is 170 μm, the number of layers of the copper mesh is 4, the surface roughness is 0.27 μm, and the static contact angle between the copper mesh and deionized water is 20.3°; for the perforated micro copper powder, the average diameter of the copper powder is 50 μm, and the average porosity is 43%; for the perforated foam copper, the average pore size of the foam copper is 170 μm, and the average porosity is 85%.

[0088] The material for preparing the surface structure for strengthening the boiling heat transfer and the heat transfer substrate disclosed in the embodiments of the present application can be not only red copper, but also other materials such as brass, bronze, aluminum, silicon, titanium and stainless steel.

[0089] In order to verify the effect of the surface structure for strengthening the boiling heat transfer disclosed in the embodiments of the present application on enhancing the heat transfer performance, the inventors take the liquid film boiling as an example and verify it by experiment. In the experiment, the arrangement of the plurality of first channels 101 is array arrangement (hereinafter referred to as perforated array), including square array and hexagonal array, and the first channels 101 are taken as through-hole channels for illustration.

[0090] Figs. 6A and 6B are respectively a field photo and a schematic diagram of a liquid film boiling experimental device. The liquid film boiling experimental device includes a liquid film boiling cavity 210, a camera module, a cooling circulation loop 230, a heating module 240 and a data measurement module 250.

[0091] The liquid film boiling cavity 210 is a closed cavity, and an observation window 211 is arranged on the liquid film boiling cavity 210. The liquid film boiling cavity 210 is provided with a heating tube, a thermocouple 251, a PID control system and a vacuum pump 260, so as to ensure that the liquid working medium boiling in the liquid film boiling cavity 210 is maintained at a preset temperature and pressure.

[0092] The camera module includes a high-speed camera 220, which can take a time-lapse photograph of the boiling phenomenon of the surface structure (hereinafter referred to as a test sample) of enhanced boiling heat transfer through the observation window 211. The cooling circulation loop 230 includes a condenser 231 and a refrigerator 232. The condenser 231 is a spiral tube condenser, and deionized water is used as the working medium to provide a cold source for the liquid film boiling device.

[0093] The heating module 240 includes a direct current power supply 241, a cylindrical heater 242, a heating block 243 and a heat insulation material 244. The heat insulation material 244 can be thermal insulation cotton or polyether ether ketone (PEEK). The cylindrical heater 242 is powered by the direct current power supply 241, and the heat insulation material 244 assists in heat preservation, so as to ensure that the test sample in the experiment obtains sufficient heat. The cross-sectional area of the heating block 243 connected to the test sample is 5mm*5mm and 10mm*10mm.

[0094] FIG. 6C is a schematic view of the arrangement of the thermocouples 251 inside the heating block 243 in the liquid film boiling device according to an embodiment of the present application. Each test sample is connected to the heating block 243 by solder. Three K-type thermocouples 251 are inserted into holes with a diameter of 1mm at a spacing of 10mm. The first thermocouple T1 is 5mm away from the top end of the heating block 243. In the experiment, the electric power input to the cylindrical heater 242 is adjusted by the direct current power supply 241 to change the heat flux density inside the heating block 243. The temperature data of the three thermocouples T1, T2 and T3 are recorded by the data acquisition instrument 253. Each power is maintained for more than 20 minutes, until the change of all temperatures within 10 minutes is less than 0.2K, reaching a steady state. Then, the heat flux density and the surface temperature of the test sample are calculated using the temperature data. According to the Taylor reverse series approximation, the heat flux density q” provided to the test sample can be calculated as: q” = k Cu [2(T2-T1) / Δx 12 -(T3-T1) / Δx 13 ], where k Cu is the thermal conductivity of copper (in the experiment, copper is taken as an example of the material of the test sample), and Δx ij is the distance between T i and T j thermocouples. The surface superheat ΔT, i.e., the wall temperature (T wall) and saturated water vapor temperature (T v The temperature difference between the two is obtained by extrapolating from the linear temperature gradient in the copper block: ΔT = T w -T v =T1-q″(δ Cu / k Cu +δ solder / k solder )-T v , where δ Cu It is the distance δ between the top thermocouple T1 and the top surface of the copper block. solder and k solder These are the solder thickness and thermal conductivity, respectively. The heat transfer coefficient h is calculated using the following formula: h = q″ / ΔT. The uncertainties of heat flux density, superheat, and heat transfer coefficient can all be determined using the standard error propagation equation: Where Y is the calculation parameter, a i These are the measurement parameters, and σ is the uncertainty. Calculation results show that the uncertainty of pressure P is ±0.075%, the uncertainty of temperature T is ±0.1K, the uncertainty of distance measurement Δx is ±0.1mm, and the uncertainty of solder thickness δ... solder The uncertainty is ±0.01 mm, the uncertainty of superheat ΔT is ±12%, the uncertainty of heat flux density q” is ±1%, and the uncertainty of heat transfer coefficient h is ±12%.

[0095] First, the inventors experimentally measured the permeability in the perpendicular thickness direction of three types of surface structures: perforated micro-copper mesh, perforated micro-copper powder, and perforated foamed copper. Figure 7A shows the physical diagram of the experimental setup, which mainly consists of two PMMA tubes with an inner diameter of 10 mm. Permeability was calculated by controlling the water flow rate and measuring the pressure difference of the liquid (deionized water) between the two PMMA tube openings. According to Darcy's law, the permeability in the thickness direction can then be calculated using the following formula: K wz =μ l u l δ w / ΔP w , where ΔP w It's a pressure difference, u l It is the water flow velocity, δ w This refers to the thickness of the sample. As shown in Figures 7B-7D, for different types of surface structures that enhance boiling heat transfer, K... wz It is obtained by linearly fitting the pressure drop to the liquid flow rate, i.e., ΔP. w =(μ l δ w / K wz )u lAs can be seen from FIG. 7B, for the perforated micro-copper mesh, at the same water flow rate, the viscous pressure drop tends to increase as the hole spacing increases, and for the same hole spacing of the perforated array, the viscous pressure drop tends to increase as the water flow rate increases.

[0096] FIG. 7C shows the curve change of the viscous pressure drop in the thickness direction with the water flow rate for the water flow through three types of surface structures of uniform micro-copper mesh, uniform micro-copper powder and uniform foam copper respectively. As can be seen from the figure, the increasing trend of the viscous pressure drop of the uniform micro-copper powder with the water flow rate is more obvious, followed by the uniform micro-copper mesh, and the uniform foam copper has the smallest increasing trend. That is, compared with the other two types of surface structures, the uniform micro-copper powder has a larger water flow resistance.

[0097] FIG. 7D is a curve change of the viscous pressure drop in the thickness direction with the water flow rate for the water flow through perforated micro-copper mesh, perforated micro-copper powder and perforated foam copper respectively. As can be seen from the figure, the increasing trend of the viscous pressure drop of the perforated micro-copper powder with the water flow rate is more obvious, followed by the perforated micro-copper mesh, and the perforated foam copper has the smallest increasing trend, which is the same as the trend of the uniform surface structure without the perforated array. At the same time, as can be seen from FIG. 7C and FIG. 7D, the viscous pressure drop of the surface structure for enhanced boiling heat transfer with the perforated array is significantly reduced compared with the surface structure without the perforated array. For example, when the water flow rate is 27 mm / s, the viscous pressure drop in the thickness direction of the water flow through the uniform micro-copper powder is about 5400 Pa, and the viscous pressure drop in the thickness direction of the water flow through the perforated micro-copper powder is about 130 Pa. It can be seen that the viscous pressure drop of the water flow through the surface structure for enhanced boiling heat transfer with the perforated array is significantly reduced, thereby verifying that the perforated array of the surface structure for enhanced boiling heat transfer can provide a low-resistance flow channel, so that the vapor bubbles can smoothly detach, the detachment direction of the vapor bubbles is consistent with the heat dissipation direction, and thus the heat transfer efficiency can be improved.

[0098] As can be seen from FIG. 8A, as the hole spacing (s p ) of the perforated array decreases, the number of the first hole channel 101 of the perforated array increases, and K wz significantly increases. FIG. 8B compares the K wz of different types of surface structures for enhanced boiling heat transfer. All the surface structures with the first hole channel 101 (perforated as shown in the figure) have a larger K wz than the surface structures without the first hole channel 101 (uniform as shown in the figure), because their flow channels are expanded.

[0099] Figure 9A is a graph of liquid film boiling heat transfer curves on perforated micro-copper mesh surfaces with different hole pitches (the heating area of the heating block 243 is 10 mm x 10 mm), and the liquid film boiling curve of the uniform micro-copper mesh without the perforated array is also shown in the graph. As can be seen from the graph, for the perforated micro-copper mesh with a hole pitch greater than 600 pm, the critical heat flux CHF and the heat transfer coefficient HTC are significantly enhanced. For example, for the perforated micro-copper mesh with a hole pitch of 900 pm, the CHF reaches 311.2 W / cm 2 at a superheat of 10.1 K, and the maximum HTC is 310.4 kW / (m 2 · K), which are 38.4% and 58.5% higher than those of the uniform micro-copper mesh, respectively. It can be seen that after the perforated array is arranged, the CHF and HTC of the liquid film boiling are significantly enhanced, i.e., the surface structure for enhancing boiling heat transfer disclosed in the embodiments of the present application has significantly enhanced heat transfer performance.

[0100] For the two types of perforated arrays, i.e., the square array and the hexagonal array, the inventors have respectively conducted experimental verification, as shown in Figure 9B, which shows the liquid film boiling heat transfer performance of the perforated micro-copper mesh surfaces with the square array and the hexagonal array under the heating area of 10 mm x 10 mm of the heating block 243. In the experiment, the diameter of the first hole channel 101 is 300 pm, and the hole pitch is 900 pm. When the type of the perforated array is changed from the square array to the hexagonal array, the CHF on the heating area of 10 mm x 10 mm decreases from 311.2 W / cm 2 to 243.2 W / cm 2 , and the maximum HTC decreases from 310.4 kW / (m 2 · K) to 245 kW / (m 2 · K). It can be seen that the square array has a better effect of enhancing heat transfer than the hexagonal array.

[0101] Figures 10A-10B show the bubble dynamic images on the perforated micro-copper mesh surfaces with the square array and the hexagonal array at a heat flux ranging from 56.7 W / cm 2 to 77.5 W / cm 2 . The arrows in the figures represent the transport path of the liquid, and the dashed line circle represents the boiling area. As can be seen from the figures, the liquid supply of the perforated micro-copper mesh surface with the square array is more sufficient, forming an ordered liquid transport path, and the boiling area is larger. The perforation of the hexagonal array increases the resistance of the liquid flow, and the liquid transport path is relatively tortuous, which hinders the flow of the liquid in the copper mesh structure, thereby resulting in a lower CHF and HTC.

[0102] The inventors have respectively conducted experiments on the boiling phenomenon of the uniform micro-copper mesh and the perforated micro-copper mesh (the hole pitches are 1500 pm and 900 pm, respectively), and the experiments are conducted at a heat flux ranging from 6.1 W / cm2 to 117.1 W / cm 2 As can be seen from FIG. 11A, for the uniform microcopper mesh, bubble nucleation is activated at a heat flux of 16.8 W / cm 2 and a superheat of 5.3 K, i.e., bubble formation begins at this parameter. As the heat flux increases, the number of bubble nucleation sites increases, and the boiling region gradually expands, as shown by the dashed line in the figure. At a higher heat flux (110.0 W / cm 2 ), the number of bubbles increases, and the bubbles tend to coalesce to form large bubbles, which hinder the flow of the liquid and the wetting of the heating surface, and can cause local dryout, triggering CHF.

[0103] FIG. 11B shows the boiling phenomenon on the perforated microcopper mesh with a hole pitch of 1500 μm. Due to the arrangement of the plurality of microscale structures 102, bubble nucleation is triggered at a heat flux of 8.2 W / cm 2 . As the heat flux increases, a plurality of bubbles simultaneously detach from the first channels 101 and the second channels 103 of the perforated array. When the heat flux exceeds 113.8 W / cm 2 , the bubbles coalesce in the copper mesh, and the steam fills a large portion of the copper mesh structure, hindering the flow of the liquid, thereby triggering the critical CHF.

[0104] FIG. 11C shows the boiling phenomenon on the perforated microcopper mesh with a hole pitch of 900 μm. Bubble nucleation is activated at a heat flux of 6.1 W / cm 2 and a superheat of 3.1 K. In the heat flux range of 6.1 W / cm 2 to 117.1 W / cm 2 , the bubbles mainly detach from the first channels 101 of the perforated array, and the liquid flows through the copper mesh structure to re-wet the heating surface, so that the liquid and the vapor transmission are not disturbed, resulting in lower liquid / vapor flow resistance and faster liquid / vapor transmission. As can be seen from the above data, compared with the uniform microcopper mesh, the perforated microcopper mesh has a lower heat flux at which bubble nucleation is triggered and a higher CHF, i.e., the arrangement of the perforated array and the plurality of microscale structures 102 can promote bubble nucleation and bubble detachment, improve the heat transfer efficiency, and enhance the heat transfer performance.

[0105] Figures 12A-12B show the boiling region area ratio (i.e., the ratio of the bubble ejection area to the total heating area) and bubble detachment frequency of three surface structures: uniform micro-copper mesh, perforated micro-copper mesh with a hole spacing of 1500 μm, and perforated micro-copper mesh with a hole spacing of 900 μm. The boiling region area ratio and bubble detachment frequency are important parameters describing the boiling heat transfer characteristics. Bubble nucleation increases with increasing heat flux density, and the boiling region area ratio of the three surface structures gradually increases with heat flux density. The perforated micro-copper mesh has a larger boiling region area than the uniform micro-copper mesh. As can be seen from Figure 12A, when the heat flux density exceeds 50 W / cm²... 2 The boiling region area of ​​the perforated micro-copper mesh with a pore spacing of 900 μm rapidly exceeds 90%, indicating that more vapor-liquid interface participates in phase change heat transfer, thereby enhancing the surface heat transfer coefficient. Figure 12B shows the variation of bubble escape frequency with heat flux density for the three types of surface structures. The bubble escape frequency increases continuously with increasing heat flux density. Due to the reduced bubble escape resistance, the bubble escape frequency of the perforated micro-copper mesh is higher than that of the uniform micro-copper mesh. Among the three types of surface structures, the perforated micro-copper mesh with a pore spacing of 900 μm has the highest bubble escape frequency, approximately 310 Hz, which is more than twice the bubble escape frequency (approximately 130 Hz) on the uniform micro-copper mesh. It can be seen that the perforated micro-copper mesh exhibits enhanced phase change heat transfer phenomena throughout the entire heat flux density range, including a larger boiling region and faster bubble escape. Therefore, the perforated array configuration significantly enhances the heat transfer effect.

[0106] Figure 13 shows the heat transfer characteristics of different types of surface structures when the perforated array is a square array. The surface structures tested include woven copper mesh structure, sintered copper powder structure and foam copper structure, all with a first hole 101 diameter of 300 pm and a hole pitch of 900 pm. Uniform refers to surface structures with only the second hole 103, composite micro-hole refers to surface structures with the second hole 103 and micro-scale structure 102, and perforated refers to surface structures with the second hole 103, micro-scale structure 102 and first hole 101. Compared with the uniform surface structure, the CHF and heat transfer HTC of each type of surface structure with composite micro-hole structure are significantly improved due to the enhanced liquid pumping capacity. In addition, compared with the composite micro-hole structure surface structure, the CHF and HTC of the perforated surface structure are further enhanced. Specifically, compared with the composite micro-hole structure surface structure, the CHF of the perforated micro-copper mesh and the perforated micro-copper powder is enhanced by 66.1% and 66.8%, respectively, and the HTC is enhanced by 77.3% and 90.2%, respectively, mainly because the first hole 101 reduces the steam flow resistance and promotes bubble detachment. However, for the foam copper structure, the perforated foam copper shows only a 6.8% CHF enhancement and a 13.2% HTC improvement compared with the composite micro-hole foam copper structure. This difference is due to the fact that the composite micro-hole foam copper already has a high porosity (about 82%) and large micro-holes (about 200 pm), so that the steam flow resistance is already low when the steam flows in the composite micro-hole foam copper. The test samples in this embodiment are suitable for two-phase heat spreaders, such as VC heat spreaders.

[0107] Figure 14 compares the measurement results of different surface structures (taking the micro-copper mesh structure as an example) under two heating areas of 5 mm x 5 mm and 10 mm x 10 mm of the heating block 243. As can be seen from the figure, the perforated micro-copper mesh (abbreviated as perforated in the figure) significantly increases the CHF and HTC compared with the other two structures under different heating areas. By reducing the area of the heating region, the flow distance of the liquid from the bottom edge to the top edge can be significantly reduced, which helps to reduce the liquid flow resistance and increase the liquid pumping speed, thereby improving the CHF and HTC of the copper mesh surface. Especially on the small heating area of 5 mm x 5 mm, the CHF of the perforated micro-copper mesh surface reaches 693.1 W / cm 2 , and the HTC is as high as 974.9 kW / (m 2 ·K).

[0108] As can be seen from the various experiments of the inventor, the arrangement of the micro-scale structures 102 increases the effective vapor bubble nucleation sites of boiling, promotes the initiation of liquid film boiling. The arrangement of the micro-scale structures 102 also improves the wettability of the surface, provides high capillary force and low resistance permeable liquid channels, allowing passive, high-flux liquid imbibition to re-wet the heated surface. The arrangement of the perforated array (the first hole 101) reduces the steam flow resistance, can promote the detachment of the bubble, thereby improves the heat transfer efficiency, and further enhances the heat transfer performance.

[0109] In addition, the application also discloses a preparation method of the surface structure for enhanced boiling heat transfer in the above embodiment, as shown in Figure 15, comprising the following steps:

[0110] S10, preparing a uniform surface structure;

[0111] The uniform surface structure comprises the second hole 103;

[0112] S20, preparing a first surface structure;

[0113] Perforating the uniform surface structure to form the first hole 101, specifically, the perforation can be achieved by mechanical processing or laser perforation.

[0114] S30, combining the first surface structure to the heat transfer substrate 110;

[0115] Combining the first surface structure to the heat transfer substrate 110 to form a combination of the heat transfer substrate 110 and the first surface structure, hereinafter referred to as the combination, specifically, the first surface structure can be combined with the heat transfer substrate 110 by vacuum sintering or protective gas sintering or electroplating, or other methods.

[0116] S40, preparing a micro-scale structure 102;

[0117] The surface of the combination of the heat transfer substrate 110 and the first surface structure is treated by etching method to form a plurality of micro-scale structures 102 on the first surface structure and the heat transfer substrate 110. Specifically, the surface can be etched by chemical etching or sandblasting or electroplating or mechanical processing, or other methods.

[0118] S50, surface modification treatment of the micro-scale structure 102;

[0119] At least a part of the micro-scale structure 102 is subjected to hydrophilic or hydrophobic surface modification treatment. Specifically, the surface modification treatment method includes but is not limited to plasma modification, surface coating modification and surface grafting modification.

[0120] Taking the laser perforation as an example, in some embodiments, the step S20 specifically comprises the following steps:

[0121] S21, importing the perforation array design pattern into the laser perforation equipment, and analyzing and processing the structure model of the perforation array (the structure model of the perforation array can be designed and drawn by using a 2D drawing software AutoCAD), so as to obtain a laser scanning sequence;

[0122] S22, adjusting the laser frequency and power of the laser perforation equipment, perforating the uniform surface structure, such as using a nanosecond laser perforation technology, exposing the structure pattern of the two-dimensional perforation array on the uniform surface structure to be prepared according to the laser scanning sequence, so as to prepare a perforated surface structure;

[0123] S23, repeating the above process on different types of uniform surface structures to form a perforation array on different types of uniform surface structures.

[0124] In the step S22, a clamp can be used to fix the uniform surface structure on the laser processing console, so as to reduce the shaking of the uniform surface structure, and thus the perforation of the uniform surface structure is more accurate to the modeling pattern of the two-dimensional perforation array.

[0125] It should be noted that the laser perforation technology herein can use various types of lasers, such as femtosecond laser, picosecond laser, nanosecond laser, etc. The structure topography left on the uniform surface structure after cutting by different types of lasers will be different, for example, using nanosecond laser can leave a relatively rough metal melting structure on the uniform surface structure. Therefore, when actually perforating, the specific laser model to be selected can be selected according to the actual situation.

[0126] Taking the mechanical drilling as an example, in some embodiments, the step S20 specifically comprises: according to the designed structure model of the perforation array, using a general lathe, a numerical control lathe or a machining center to drill the uniform surface structure, so as to obtain a perforated surface structure.

[0127] In some embodiments, the step S30 specifically comprises the following steps:

[0128] S31, fixing the heat transfer substrate 110 and the first surface structure together by using a clamp to form a combination;

[0129] S32, placing the combination into a vacuum high-temperature sintering furnace for sintering, so as to combine the first surface structure on the surface of the heat transfer substrate 110 to form a combination of the two.

[0130] In some embodiments, before the step S30, a pretreatment step S20' is further included, and the pretreatment step S20' specifically comprises the following steps:

[0131] S21', polishing the surface of the heat transfer substrate 110;

[0132] S22', cleaning the heat transfer substrate 110 and the first surface structure after polishing.

[0133] Specifically, the first surface structure and the heat transfer substrate 110 after polishing are sequentially cleaned in an ultrasonic cleaning bath using an oil cleaning solvent, an alcohol solvent, an acid solution and deionized water. The oil cleaning solvent is used to clean the oil stains on the surface of the heat transfer substrate 110 and the first surface structure, the alcohol solvent is used to clean the oil cleaning solvent remaining on the surface of the heat transfer substrate 110 and the first surface structure, the acid solution is used to remove oxides such as copper oxide on the surface of the heat transfer substrate 110 and the first surface structure, and the deionized water is used to clean the residual acid solution. During the above cleaning process, the heat transfer substrate 110 and the first surface structure can be soaked in the cleaning reagent for 3 to 20 minutes, and the mass percentage of dilute sulfuric acid can be selected as 5%.

[0134] In the embodiments of the present application, the oil cleaning solvent, the alcohol solvent and the acid solution can all be multiple, for example, the oil cleaning solvent can use acetone or toluene or ethyl acetate; the alcohol solvent can use anhydrous ethanol or isopropyl alcohol; and the acid solution can use 5% dilute sulfuric acid or 2M dilute hydrochloric acid solution (containing 2 moles of hydrochloric acid molecules per liter of solution).

[0135] The pre-treatment step S20' in the embodiments of the present application removes burrs, oil stains and oxides existing on the surface of the heat transfer substrate 110, so that the first surface structure can be more closely combined on the surface of the heat transfer substrate 110.

[0136] In some specific embodiments, the step S40 is realized by a chemical etching method, specifically including the following steps:

[0137] S41, preparing an oxidation structure, immersing the combination into a hot alkaline chemical solution or a strong oxidizing solution to form an oxidation structure;

[0138] S42, removing the oxidation structure, using an acid solution to remove the oxidation structure on the surface of the combination and forming a micro-scale structure 102 on the surface.

[0139] The chemical etching method of the combination using a hot alkaline solution or a strong oxidizing solution can be various. For example, the combination can be immersed in an alkaline solution mixed by NaClO2, NaOH, Na3PO4·12H2O and deionized water at a ratio of 3.75:5:10:100 wt% at a temperature of 60-90℃ for 5-50 minutes; or the combination can be immersed in a 30% H2O2 solution at room temperature for 3-8 hours; or the combination can be immersed in a combined solution of 2.5M NaOH and 0.1M (NH4)2S2O8 at a temperature of 5-85℃ for 5-30 minutes. These methods can form an oxidation structure on the surface of the first surface structure and the heat transfer substrate 110.

[0140] In the embodiments of the present application, the methods for removing the surface oxidation structure using an acidic solution are various, for example, a 5% mass percent dilute sulfuric acid or a 2M dilute hydrochloric acid solution can be used.

[0141] It should be noted that the above description of the oil stain cleaning solvent, the alcohol solvent, the alkaline solution, the strong oxidizing solution, the chemical oxidation reaction temperature, the chemical oxidation reaction time, the mass percent of the dilute sulfuric acid and the mole percent of the dilute hydrochloric acid is only an example in the embodiments of the present application, and is not the only limitation of the embodiments of the present application.

[0142] The preparation method of the enhanced boiling heat transfer surface structure disclosed in the embodiments of the present application has the advantages of simple steps, reasonable design, easy implementation, strong operability, convenient scale production, important practical value and popularization significance.

[0143] It should be noted that each embodiment in the present specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts of each embodiment can be referred to each other.

[0144] As shown in the present application and claims, unless the context clearly indicates otherwise, the words "one", "an", "a", and / or "the" do not specifically refer to the singular, but also include the plural. Generally, the terms "comprise" and "include" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements. The element defined by the statement "comprising a" does not exclude the presence of another same element in the process, method, product or device comprising the element.

[0145] In the following, the terms "first" and "second" are only used for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features.

[0146] The principles and implementations of the present application have been described in specific examples. The above examples are only used to help understand the core idea of the present application. It should be pointed out that, for ordinary skilled persons in the technical field, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A surface structure for enhancing boiling heat transfer, characterized by, The surface structure for enhanced boiling heat transfer is combined on a heat transfer substrate (110) and has first holes (101) for vapor bubble departure, microscale structures (102) for promoting vapor bubble nucleation, and second holes (103) for liquid suction; The first holes (101) have a larger hole diameter than the second holes (103), and the second holes (103) have a larger hole diameter than the width of the microscale structures (102); The first holes (101), the microscale structures (102), and the second holes (103) are each multiple in number.

2. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The arrangement of the multiple first holes (101) includes at least one of an array arrangement or a random arrangement. The array arrangement includes at least one of a square array, a rectangular array, a ring array, and a hexagonal array.

3. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The cross-sectional shape of the first holes (101) includes at least one of a triangle, a rectangle, a rhombus, a pentagon, a hexagon, a circle, an ellipse, and a star; and / or, The type of the microscale structures (102) includes at least one of a cavity, a micro-hole, and a crack.

4. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The first holes (101) are configured as blind hole channels on the surface structure for enhanced boiling heat transfer. Alternatively, The first holes (101) are configured as through-hole channels on the surface structure for enhanced boiling heat transfer. Alternatively, 5. The surface structure for enhanced boiling heat transfer according to claim 4, wherein Some of the first holes (101) are configured as blind hole channels on the surface structure for enhanced boiling heat transfer, and the rest of the first holes (101) are configured as through-hole channels on the surface structure for enhanced boiling heat transfer.

6. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The first holes (101) include at least one of a diverging channel, a converging channel, and a uniform channel. The first holes (101) have a hole diameter of 10 μm-1000 μm, and a spacing between adjacent two first holes (101) of 15 μm-5000 μm; and / or, 7. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The microscale structures (102) have a height of 0.1 μm-20 μm and a height-to-width ratio greater than 2.

8. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The second holes (103) have a hole diameter of 10 μm-500 μm, and the skeleton of the surface structure for enhanced boiling heat transfer has a diameter or width of 20 μm-100 μm.

9. The surface structure for enhanced boiling heat transfer according to claim 1, wherein The surface structure for enhanced boiling heat transfer includes one or more of a multi-layer woven mesh, a sintered powder, a foam metal, a groove, a micro-pillar array, and an electrodeposited porous structure. The material for preparing the surface structure for enhanced boiling heat transfer includes one or more of red copper, brass, bronze, aluminum, silicon, titanium, and stainless steel; and / or, 10. A method for producing a surface structure for enhanced boiling heat transfer, for producing a surface structure for enhanced boiling heat transfer according to any one of claims 1 to 9, characterized in that The material for preparing the heat transfer substrate (110) includes one of red copper, brass, bronze, aluminum, silicon, titanium, and stainless steel. The method includes: preparing a uniform surface structure including the second holes (103); preparing a first surface structure, perforating the uniform surface structure to form the first surface structure having the first holes (101); combining the first surface structure to the heat transfer substrate (110) to form a combination of the two. The micro-scale structures (102) are prepared by etching the surface of the combination of the heat transfer substrate (110) and the first surface structure to form a plurality of the micro-scale structures (102) on the first surface structure and the heat transfer substrate (110). The micro-scale structures (102) are subjected to surface modification treatment, and at least a portion of the micro-scale structures (102) are subjected to hydrophilic or hydrophobic surface modification treatment.

11. The method of producing an enhanced boiling heat transfer surface structure according to claim 10, characterized in that The method further comprises a pretreatment step before the step of combining the first surface structure to the heat transfer substrate (110), and the pretreatment step specifically comprises: polishing the surface of the heat transfer substrate (110); cleaning the heat transfer substrate (110) and the first surface structure after polishing.

12. The method of producing an enhanced boiling heat transfer surface structure according to claim 10, wherein The etching method at least comprises one of chemical etching, sandblasting, electroplating and mechanical processing.

13. The method of producing an enhanced boiling heat transfer surface structure according to claim 10, wherein The hydrophilic or hydrophobic surface modification treatment at least comprises one of plasma modification, surface coating modification and surface grafting modification.

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