A surface unit with bionic grass leaf surface wedge-shaped piece, preparation method and condensation strengthening surface structure

Abstract

The present application belongs to the technical field of condensation enhancement, and relates to a surface unit with bionic grass leaf surface wedge-shaped pieces, comprising a heat conduction plate and a plurality of bionic grass leaf surface wedge-shaped pieces connected to the heat conduction plate; the length of the bionic grass leaf surface wedge-shaped piece is greater than the thickness, and the shape is triangular. A preparation method thereof is also disclosed, wherein the bionic grass leaf surface wedge-shaped pieces are made of a metal plate with heat conduction performance by means of striping, slant cutting and pricking; one side of each bionic grass leaf surface wedge-shaped piece coincides with the edge of the metal strip, and the other side is obtained by slant cutting. The present application also discloses a bionic condensation enhancement surface structure, which can be applied to a condensation pipeline to be enhanced and also can be applied to a condensation surface to be enhanced; when liquid drops are self-transported to the bottom of the triangular piece by surface force, coalescence of the liquid drops obtained by condensation at the bottom occurs; when the liquid drops contact the super-hydrophilic flow guide wire, the liquid drops are quickly sucked and leave the surface, so that the metal condensation enhancement surface is exposed for the next round of collection, and the liquid drop accumulation phenomenon at the bottom of the traditional fin design fin is effectively prevented.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of condensation enhancement, and particularly relates to a surface unit with bionic grass leaf surface wedge-shaped sheet, a preparation method and a condensation enhancement surface structure. BACKGROUND

[0002] In people's industrial production and daily life, condensation is widely used as an efficient energy transfer method. In industrial applications, water in the power generation cycle is converted between liquid and gas. In order to reduce the damage caused by impurities in hard water to the steam turbine, the water quality used for circulation and cooling is different. The water used for circulation is high-purity softened water, which needs to be condensed into liquid in the condenser after power generation to be completely recycled for the next cycle. In indoor condensation and dehumidification, efficient collection of air moisture during condensation is also pursued. In addition, the condensation process also needs to achieve energy-saving cooling effect for the required working medium or environment, that is, to pursue lower heat loss in the condensation process to obtain higher heat transfer efficiency. From the above common application examples of condensation surface, it can be seen that whether in industrial field or daily life, the dual goals of maximizing condensation into liquid and achieving the highest heat transfer efficiency in the condensation process are often pursued.

[0003] Traditional condensation surfaces are liquid-wetted surfaces, which are mostly film condensation. The condensed liquid cannot be separated from the condensation surface in time, and the condensation surface often forms a continuous liquid film, which hinders the further contact of steam with the metal condensation surface. Compared with metal, the thermal conductivity of liquid is reduced by an order of magnitude, which is a poor conductor of heat, greatly affecting the heat transfer efficiency of the condensation surface. Researchers have found that the means of strengthening condensation is to thin the liquid film and discharge the liquid in time. On this basis, various condensation strengthening fins are designed, which use two-dimensional or three-dimensional fins to enhance convection, strengthen heat transfer, and thin the liquid film. However, the bottom of the two-dimensional or three-dimensional fins is easy to deposit a thick liquid film, and the related research on directional liquid discharge is not sufficient, and the effect of condensation strengthening is limited.

[0004] Compared with film condensation, the condensate on the treated metal surface presents a pearl-like condensation, and as the condensation proceeds, the liquid pearl grows continuously, and the surface is refreshed quickly, and the heat transfer efficiency is greatly improved compared with the film condensation. In recent years, researchers have designed many enhanced condensation surfaces for realizing pearl-like condensation by using laser processing combined with chemical reagents, and the heat transfer efficiency of the condensation process is improved. However, the premise of this new type of condensation enhanced heat transfer surface to pursue pearl-like condensation is to transform the traditional metal surface into a liquid-repellent or super-liquid-repellent surface, and the steam is not easy to condense on the hydrophobic surface, and the heat transfer efficiency is improved at the same time. In addition, the application of chemical reagents on the surface causes certain pollution to the collected condensate, and the application is limited for high-purity softened water or other condensers; with the extension of the use time limit, the hydrophobic or super-hydrophobic condensation surface prepared by the method often appears surface failure, and the phenomenon of "flood" reappears film condensation, so in the preparation of the new type of enhanced condensation surface, the chemical reagents should be attached to the surface as much as possible to realize the liquidophilic modification to obtain long-term surface condensation enhancement effect.

[0005] From the current research on the condensation enhanced surface, it can be seen that the current technology often focuses on the single target of enhancing heat transfer or improving the amount of condensed liquid, and it is difficult to meet the dual targets of enhancing heat transfer and improving the amount of condensed liquid. In order to improve the amount of condensed liquid, the whole condensation surface should be kept hydrophilic, and in order to enhance the heat transfer efficiency and thin the liquid film in time, new means should be explored to drain the liquid in time. SUMMARY

[0006] The purpose of the present application is to provide a surface unit with bionic grass leaf surface wedge-shaped piece, preparation method and condensation enhanced surface structure, which realizes the directional self-refreshing of the condensate on the condensation surface through the bionic structure, solves the problem that the traditional condensation surface forms a continuous liquid film, the condensate cannot be separated from the surface in time, the heat transfer efficiency is low, and the condensate collection rate is low.

[0007] The present application is realized by the following technical solutions:

[0008] A surface unit with bionic grass leaf surface wedge-shaped piece, comprising a heat conduction plate and a plurality of bionic grass leaf surface wedge-shaped pieces connected to the heat conduction plate.

[0009] The length of the bionic grass leaf surface wedge-shaped piece is greater than the thickness, and the shape is triangular.

[0010] Further, the thickness d of the bionic grass leaf surface wedge-shaped piece is 0.1mm-5mm, the top angle a is 5°-45°, and the length L is 1mm-50mm.

[0011] The preparation method of the surface unit with the bionic grass leaf surface wedge-shaped piece is as follows: a metal plate with heat conduction performance is cut into strips and pieces, and is obliquely cut to form a spike, one side of each bionic grass leaf surface wedge-shaped piece coincides with the edge of the metal strip, and the other side is obtained by oblique cutting.

[0012] Further, the method specifically comprises the following steps:

[0013] S1, cutting a metal plate with heat conduction performance with a thickness of d into metal strips with a width of D;

[0014] S2, cutting a plurality of penetrating notches on the edge of the metal strip as a wedge-shaped edge to form a planar triangular wedge-shaped piece; the wedge-shaped edge and the edge of the metal strip form an angle of a;

[0015] S3, after the planar triangular wedge-shaped piece is cut, the planar triangular wedge-shaped piece is bent upward by using a metal bending process to obtain a plurality of bionic grass leaf surface wedge-shaped pieces.

[0016] Further, the surface of the bionic grass leaf surface wedge-shaped piece is a hydrophilic surface, and the contact angle between the hydrophilic surface and water is 30°-90°.

[0017] Further, a is 5°-45°;

[0018] The unbent metal strip serves as a bottom plate, and after the planar triangular wedge-shaped piece is bent upward, the planar triangular wedge-shaped piece and the bottom plate form an angle, and the angle ranges from 30° to 150°.

[0019] Further, the width D of the metal strip is 0.5 mm-50 mm, the thickness d is 0.1 mm-5 mm, and the length L of a single triangular wedge-shaped piece is 1 mm-50 mm;

[0020] The wedge-shaped spacing between adjacent planar triangular wedge-shaped pieces is b, and b is 2 mm-50 mm.

[0021] A bionic condensation strengthening surface structure, wherein a flow guide wire and the surface unit are wound on a pipeline to be strengthened in an alternating manner, and the wound flow guide wire and surface unit are tightly combined with the pipeline by thermal expansion;

[0022] The bionic grass leaf surface wedge-shaped piece faces the pipeline outward in the radial direction.

[0023] A bionic condensation strengthening surface structure, wherein a heat-conducting silicone layer is coated on a planar surface to be condensed and strengthened, and a flow guide wire and the surface unit are arranged on the heat-conducting silicone layer in an alternating manner.

[0024] Further, the flow guide wire comprises the following two preparation methods:

[0025] Preparation method one: the flow guide wire is ground in the radial direction by using sandpaper to increase the surface roughness and longitudinal flow guide microchannels of the metal wire;

[0026] Preparation method two: the guide wire is subjected to super-hydrophilic treatment, the metal wire is soaked in an acidic solution at room temperature, the surface of the guide wire is corroded to present a micro-nano structure, and the liquid affinity is enhanced.

[0027] Compared with the prior art, the present application has the following beneficial technical effects:

[0028] The present application discloses a surface unit with a bionic grass leaf surface wedge-shaped sheet, the design of the bionic grass leaf makes the tip and edge of the triangular sheet provide sufficient condensation nucleation sites, which is conducive to realizing the shaping of the condensate, and the wedge-shaped sheet structure promotes the condensate drops on the surface to be affected by surface forces during growth, so that the self-refreshing of the transport of the drops from the tip to the bottom is spontaneously driven, and timely drainage on the single planar triangular wedge-shaped sheet is realized.

[0029] The planar triangular wedge-shaped sheet basic unit has the following advantages when collecting water mist or condensate: the edge and the tip of the triangular wedge-shaped metal sheet of the bionic grass leaf provide a large number of condensation nuclei, which is conducive to condensation at the above-mentioned positions; as the condensation or water mist collection further proceeds, the condensate drops gradually grow and coalesce with each other, and due to the fact that the length of the triangular wedge-shaped metal sheet is significantly greater than the thickness, the condensate drops are mainly attached to the wedge-shaped surface.

[0030] As the position of the drops gradually changes in the planar triangular wedge-shaped sheet towards the wide bottom of the triangular sheet, the solid-liquid interface contact area gradually increases, causing the free energy to decrease, and the capillary force imbalance along the axis of the triangular sheet drives the drops to spontaneously transport to the equilibrium position with the lowest free energy. Intuitively, due to the fact that the drops are limited by the two narrow edges of the planar triangular wedge-shaped sheet and cannot fully spread on the surface of the triangular sheet, the drops move on the surface of the triangular wedge-shaped sheet towards the root of the triangular sheet under the action of the capillary force, the contact area of the drops and the hydrophilic solid surface continuously increases, and the drops gradually tend to the final equilibrium position where the drops are located at the root of the triangular sheet.

[0031] Further, the equilibrium positions of condensate drops of different sizes on the planar wedge-shaped surface are different (the larger the volume of the condensate drops, the farther the equilibrium position of the condensate drops on the planar wedge-shaped surface from the tip), and the capillary force generated thereby spontaneously drives the growing condensate drops to complete the transport from the tip to the bottom of the wedge, realizing the rapid condensation of the condensate on a single planar wedge-shaped sheet and the local continuous self-refreshing of a single triangular sheet.

[0032] The present application also discloses a preparation method of the surface unit with the bionic grass leaf surface wedge-shaped sheet, and due to the bending of the triangular sheet, after the surface unit is installed, a condensation pipeline to be strengthened or a condensation plane to be strengthened naturally forms a surface unit with a bionic grass leaf surface wedge-shaped sheet as shown in the figure. Figure 6The multiple triangular wedge-shaped recessed micro-channels are shown, the liquid drops transported to the bottom of the planar triangular wedge-shaped sheet are subjected to similar surface force when contacting the triangular recess, spontaneously complete the suction of the surface liquid drops, and quickly separate from the surface under the action of the super-hydrophilic guide wire.

[0033] The application further discloses a bionic condensation reinforced surface structure which can be applied to a pipeline to be reinforced for condensation or a surface structure to be reinforced for condensation. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a schematic diagram of a single bionic grass leaf surface wedge-shaped sheet structure of the application.

[0035] Figure 2 It is a schematic diagram of providing sufficient condensation nucleation sites for the tip and edge of a single bionic grass leaf surface wedge-shaped sheet.

[0036] Figure 3 It is a schematic diagram of the directional self-transportation of liquid drops from the tip to the bottom.

[0037] Figure 4 It is a flow chart of preparing a surface unit with a bionic grass leaf surface wedge-shaped sheet.

[0038] Figure 5 It is a schematic diagram of installing the surface unit and the guide wire in a pipeline.

[0039] Figure 6 It is a schematic diagram of preparing the surface unit and installing the surface unit and the guide wire in a pipeline to be reinforced for condensation.

[0040] Figure 7 It is a schematic diagram of the directional suction of the liquid drops transported to the bottom of the triangular sheet by the triangular recess and the metal guide wire to separate the liquid drops from the condensation surface.

[0041] Figure 8 It is a calculation result of the free energy of six liquid drops with different volumes on the triangular wedge-shaped surface varying with positions (Z coordinate is the axial distance from the tip of the triangular sheet, and the circle encloses the position of the lowest free energy, i.e., the equilibrium position of the liquid drops on the triangular wedge-shaped surface).

[0042] Figure 9The calculation results of the directional capillary forces on the triangular wedge surface of six different volume droplets with the distance from the tip.

[0043] 1, the condenser pipeline to be strengthened; 2, the flow guide wire; 3, the bionic grass leaf surface wedge-shaped sheet; 4, the condenser plane to be strengthened. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the following will be further described in detail in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application, that is, the described examples are only a part of the examples of the present application, but not all examples.

[0045] The components described and illustrated in the drawings and examples of the present application can be arranged and designed in various different configurations, therefore, the detailed description of the examples of the present application provided in the following drawings is not intended to limit the scope of the claimed present application, but only to represent a selected embodiment of the present application. Based on the drawings and examples of the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0046] It should be noted that the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, element, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed, or further includes the elements inherent to the process, element, method, article or equipment.

[0047] The present application is inspired by the dew drops hanging on the grass leaves in the early morning, the unique planar triangular wedge structure of the grass leaves provides sufficient condensation nucleation sites at the edges, the triangular wedge surface can provide a surface force from the wedge tip to the wedge root on the dew drops thereon, driving the dew drops to move towards the root of the grass leaves, having excellent self-refreshing effect, which is a new means of timely removing surface condensate and realizing directional delivery of condensate.

[0048] The present application proposes a planar triangular wedge sheet structure designed by the bionic grass leaf as shown in Figure 1 The design of the bionic grass leaf provides sufficient condensation nucleation sites at the tip and edges of the triangular sheet, which is beneficial to realize the shaping of the condensate (as shown in Figure 2 ).

[0049] With the further condensation or water mist collection, the condensate droplets gradually grow and coalesce with each other. Since the length L of the triangular wedge sheet is obviously greater than the thickness d, the condensate droplets are mainly attached to the wedge surface.

[0050] According to the free energy formula of the droplets on the surface:

[0051] G = γ SV A SV + γ SL A SL + γ LV A LV

[0052] where G is the surface energy, A is the interfacial surface area, and the subscripts SV, SL, and LV refer to solid-vapor, solid-liquid, and liquid-vapor interfaces, respectively. Taking water as an example, γ SL << γ SV ≈ γ LV .

[0053] As the droplet position changes gradually in the direction of the root of the planar triangular wedge-shaped sheet, the solid-liquid interfacial contact area A SL increases gradually, causing the free energy to decrease, thus triggering the capillary force imbalance along the axis of the triangular sheet to drive the droplet to spontaneously transport to the equilibrium position with the lowest free energy (as shown in Figure 3 , Figure 8 Intuitively, since the droplet is limited by the two narrow edges of the planar triangular wedge-shaped sheet and cannot fully spread on the surface of the triangular sheet, under the action of capillary force, the droplet moves on the surface of the triangular wedge-shaped sheet towards the root of the triangular sheet, and the contact area of the droplet with the hydrophilic solid surface increases gradually, gradually tending towards the final equilibrium position of the droplet at the root of the triangular sheet (as shown in Figure 3 , Figure 8 .

[0054] The equilibrium positions of condensation droplets of different sizes on the planar wedge-shaped surface are different (the larger the volume of the condensation droplet, the farther the equilibrium position of the condensation droplet on the planar wedge-shaped surface from the tip) (as shown in Figure 8 ), and the surface force thus generated spontaneously drives the growing condensation droplet to complete the transport from the tip to the bottom of the wedge-shaped sheet, realizing rapid condensation of condensation liquid on a single planar wedge-shaped sheet and local and continuous self-refreshing of a single triangular sheet.

[0055] When the droplet is self-transported to the bottom of the triangular sheet by surface force, it coalesces with the droplet condensed at the bottom and further grows. When it contacts the superhydrophilic flow guide wire 2, it will be quickly sucked away from the surface, exposing the metal condensation strengthening surface for the next round of collection (as shown in Figure 7 ), effectively preventing the accumulation of droplets at the bottom of the traditional fin design.

[0056] The slitting and sheeting, and the oblique cutting and pricking process not only facilitate the installation of the next new bionic reinforced condensing surface, but also greatly reduce the cost and processing time of laser cutting or line cutting processing of the planar triangular wedge-shaped surface by combining one side of each triangular sheet with the edge of the slitting. In the bending of the triangular wedge-shaped sheet, the thickness of the selected metal sheet is small (0.1-5 mm), and the hardness of the heat-conducting metal (aluminum or copper) is low, so the bending of the metal sheet is low in cost.

[0057] The application discloses a surface unit with Figure 1 The surface unit with the bionic grass leaf surface wedge-shaped sheet 3 comprises a heat-conducting plate and a plurality of bionic grass leaf surface wedge-shaped sheets 3 connected to the heat-conducting plate.

[0058] The preparation method of the surface unit with the bionic grass leaf surface wedge-shaped sheet 3 comprises the following steps of slitting and sheeting and oblique cutting and pricking to prepare a planar wedge-shaped triangular sheet metal strip (as shown in the drawing). Figure 4 The specific manufacturing process is as follows.

[0059] First, an aluminum plate, a copper plate or other metal sheet with good heat conduction is cut and slit into a metal strip with a width of D (D can be 0.5-50 mm). Then, a penetrating notch with a wedge-shaped edge length of l, an angle of α with respect to the edge of the metal strip and a spacing of b is cut on the edge of the slitted metal strip by laser cutting or line cutting. The width D of the metal strip can be 2 mm-50 mm, and the thickness d can be 0.1 mm-5 mm. The edge length l of a single triangular wedge-shaped sheet can be 1 mm-50 mm (l>>d to ensure that the cut planar triangular wedge-shaped surface is close to the shape of a grass leaf), the spacing b of the planar triangular wedge-shaped sheet can be 2 mm-50 mm, and the top angle α can be 5°-45°. Then, the triangular metal sheet is bent to an angle of γ with respect to the bottom plate by using a mold or other common metal sheet bending method, and γ can be 30°-150°.

[0060] Based on the prepared planar wedge-shaped triangular sheet metal strip, the installation method of the new bionic surface reinforced condensing surface on the surface of a copper pipe is slightly different.

[0061] The installation method of the new bionic condensing reinforced surface structure on the surface of a copper pipe is as follows.

[0062] Method one: the prepared surface unit with a planar triangular wedge-shaped sheet (as shown in the drawing) is wound on a copper pipe that needs to be reinforced and condensed. Figure 4 Further, the bionic reinforced condensing surface wound on the copper pipe is tightly combined with the copper pipe by using the thermal expansion method (as shown in the drawing). Figure 5

[0063] ​Method two: a thin layer of thermal conductive silicone grease is coated on the surface of the copper pipe, and then the polished flow guide wire 2 is wound on the copper pipe with the aforementioned metal strip with a flat triangular wedge-shaped piece (ensure that the flat wedge-shaped triangular piece is oriented radially outward during installation), thereby completing the installation of the new bionic condensation strengthening surface on the copper pipe (as shown in Figure 5

[0064] In addition to being applicable to the condensation strengthening pipeline 1, it can also be applied to the condensation strengthening plane 4. The installation method of the new bionic condensation strengthening surface on the plane surface is as follows: a thin layer of thermal conductive silicone grease is coated on the required condensation strengthening surface, and then the polished flow guide wire 2 is arranged on the required condensation strengthening plane with the aforementioned metal strip with a flat triangular wedge-shaped piece, thereby completing the installation of the new bionic condensation strengthening surface on the plane. Figure 6

[0065] Due to the bending of the triangular piece, after the surface unit is installed, a plurality of triangular wedge-shaped recessed microchannels are naturally formed on the condensation strengthening pipeline or the condensation strengthening plane (as shown in Figure 6 When the liquid droplets transported to the bottom of the flat triangular wedge-shaped piece come into contact with the triangular groove, they are subjected to similar surface forces as the flat triangular piece surface, spontaneously completing the pumping of the surface liquid droplets, and rapidly separating from the surface under the action of the super-hydrophilic flow guide wire 2 (as shown in Figure 7

[0066] Due to the orderly arrangement of the super-hydrophilic flow guide wire 2, the final condensation droplet falling direction is macroscopically controllable, avoiding the problem of unordered macroscopic falling of traditional condensation strengthening surface condensation liquid, which makes it difficult to arrange the collection device. While ensuring the hydrophilic surface, it realizes the energy-free rapid directional self-refreshing of the condensation droplets on the condensation surface, and realizes the dual improvement of the condensation liquid quantity and the heat exchange efficiency.

[0067] There are two methods for preparing the flow guide wire 2, as follows:

[0068] Method one for preparing the flow guide wire 2: the flow guide wire 2 (aluminum, copper or other metals) with a wire diameter φ ranging from 0.3 to 3 mm is polished along the radial direction using 100-300 mesh sandpaper to increase the surface roughness and longitudinal flow guide microchannels of the metal wire.

[0069] Method two for preparing the flow guide wire 2: to obtain better surface condensation droplet self-refreshing effect, the flow guide wire 2 can be subjected to super-hydrophilic treatment. A 0.1-5 mol / L acidic solution such as nitric acid, hydrochloric acid, sulfuric acid, or oxalic acid is used to soak the metal wire at room temperature for 0.1-30 min, so that the metal wire surface is corroded to form a micro-nano structure, enhancing its liquid affinity and better playing the flow guide effect of the metal wire.

[0070] ​​​In view of the possible residual problem of the condensate at the bottom of the planar triangular wedge-shaped sheet, the acid corrosion super-hydrophilic wire is used as a flow guide pipe, which is wound on the copper pipe in need of enhanced condensation with the aforementioned metal strip with planar triangular wedge-shaped sheets, the metal wire timely guides the liquid drops at the bottom of the planar triangular wedge-shaped sheet, and under the action of gravity, the condensate is oriented to fall off at the lower part of the condensing pipe, the directional separation of the condensate on the whole structure of the condensing surface is completed, and the self-refreshing of the condensing surface is realized.

[0071] As shown in Figure 8 The calculation results of the free energy of different droplet sizes at different positions of the triangular wedge-shaped surface are shown in the figure (contact angle 60 degrees, half cone angle 2.5 degrees, cone length 3mm, Z coordinate is the distance from the tip of the triangular sheet, and the circle encloses the position of the lowest free energy, that is, the equilibrium position of the droplet on the triangular wedge-shaped plane). It can be seen from the calculation results that the larger the droplet size, the farther the equilibrium position from the tip of the triangular sheet, that is, as the condensation process accumulates, the condensate droplets continuously grow, coalesce and spontaneously complete the transport to the bottom of the triangular sheet.

[0072] As shown in Figure 9 The calculation results of the free energy of different droplet sizes at different positions of the triangular wedge-shaped surface are shown in the figure (contact angle 60 degrees, half cone angle 2.5 degrees, cone length 3mm, Z coordinate is the distance from the tip of the triangular sheet, and the circle encloses the position of the lowest free energy, that is, the equilibrium position of the droplet on the triangular wedge-shaped plane). It can be seen from the calculation results that the larger the droplet size, the farther the equilibrium position from the tip of the triangular sheet, that is, as the condensation process accumulates, the condensate droplets continuously grow, coalesce and spontaneously complete the transport to the bottom of the triangular sheet.

[0073] The numerical simulation of the spontaneous completion of the droplet from the tip to the bottom of the single planar triangular wedge-shaped sheet under the action of surface force in less than 10ms is carried out by using Ansys Fluent software (contact angle 60 degrees, half cone angle 2.5 degrees, cone length 3mm, droplet 0.1μL).

[0074] Compared with the existing condensation enhancement surface relying on chemical reagents to achieve beaded condensation, the present application does not attach any chemical reagents, and relies on the unique design and configuration to realize the self-refreshing of the condensate on the condensing surface, while reducing the pollution to the refrigerant.

[0075] Compared with the widely used two-dimensional or three-dimensional overall finned tube, the unique grass leaf-shaped design provides more condensation nucleation sites, and the planar wedge-shaped surface design enables the directional self-refreshing of the condensate droplets on the single planar triangular wedge-shaped sheet, the surface unit and the triangular groove formed by the installation on the surface to be enhanced condensation 4 jointly act on the metal super-hydrophilic flow guide wire 2, and the liquid film at the root of the planar wedge-shaped triangular sheet is directionally and rapidly thinned, realizing the rapid directional self-refreshing and overall directional liquid discharge of the condensate during the condensation process, which is advanced for realizing the enhanced condensation heat exchange efficiency and the rapid collection of the condensate during the condensation process.

[0076] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement should be covered in the protection scope of the claims of the present application.

Claims

1. A surface unit with bionic grass leaf surface wedgelets, characterized in that, The surface unit comprises a heat-conducting plate and a plurality of bionic grass leaf surface wedge-shaped pieces (3) connected to the heat-conducting plate. The bionic grass leaf surface wedge-shaped piece (3) is triangular in shape. The heat-conducting plate is a metal strip cut from a metal plate with thermal conductivity. Several through-cuts are made along the edges of the metal strips to form wedge-shaped sides, creating a planar triangular wedge-shaped plate. The angle between the wedge-shaped sides and the edges of the through-cuts on the metal strip is [value missing]. , The angle is 5° to 45°. The length L of the wedge-shaped edge is 1 mm to 50 mm. The thickness d of the bionic grass leaf surface wedge-shaped piece (3) is 0.1 mm to 5 mm. The length L is greater than the thickness d.

2. The method for preparing the surface unit with the biomimetic grass leaf wedge as described in claim 1, characterized in that, Each bionic grass leaf surface wedge-shaped piece (3) is formed by slitting, beveling and cutting a metal plate having heat-conducting properties, one edge of each bionic grass leaf surface wedge-shaped piece (3) coincides with the edge of the metal strip, and the other edge is obtained by beveling cutting. Specifically, the method comprises the following steps: S1, cutting a metal plate having heat-conducting properties with a thickness d into a metal strip with a width D; S2, cutting a plurality of penetrating notches on the edge of the metal strip as wedge-shaped edges to form planar triangular wedge-shaped pieces; S3, after the planar triangular wedge-shaped pieces are cut, the planar triangular wedge-shaped pieces are bent upward by using a metal bending process to obtain a plurality of bionic grass leaf surface wedge-shaped pieces (3).

3. The method for preparing the surface unit with the biomimetic grass leaf wedge as described in claim 2, characterized in that, The surface of the bionic grass leaf surface wedge-shaped piece (3) is a hydrophilic surface, and the contact angle between the hydrophilic surface and water is 30° to 90°.

4. The method for preparing the surface unit with the biomimetic grass leaf wedge as described in claim 2, characterized in that, The unbent metal strip serves as a bottom plate, and after the planar triangular wedge-shaped pieces are bent upward, the planar triangular wedge-shaped pieces form an included angle with the bottom plate, and the included angle ranges from 30° to 150°.

5. The method of claim 2, wherein the surface unit with the biomimetic grass blade face wedge is prepared by the steps of: The width D of the metal strip is 0.5 mm to 50 mm. The wedge-shaped spacing between adjacent planar triangular wedge-shaped pieces is b, and b is 2 mm to 50 mm.

6. A biomimetic condensation-enhancing surface structure, characterized by The surface unit and the flow guide wire (2) are wound on the condenser pipeline (1) to be strengthened, and the wound surface unit and flow guide wire (2) are tightly combined with the pipeline by thermal expansion; The bionic grass leaf surface wedge-shaped piece (3) is radially directed outward from the pipeline.

7. A biomimetic condensation-enhancing surface structure, characterized by A heat-conducting silicone grease layer is coated on the surface of the condenser plane (4) to be strengthened, and the flow guide wire (2) and the surface unit are arranged on the heat-conducting silicone grease layer.

8. A surface structure for condensation according to claim 6 or 7, wherein The flow guide wire (2) comprises the following two preparation methods: Preparation method one: the flow guide wire (2) is ground along the radial direction with sandpaper to increase the surface roughness and longitudinal flow guide microchannels of the metal wire; Preparation method two: the flow guide wire (2) is subjected to super-hydrophilic treatment, and the metal wire is soaked in an acidic solution at room temperature to corrode the surface of the flow guide wire (2) to present a micro-nano structure and enhance the liquid affinity.

Images