Porous oil-filled metal surface capable of strengthening dropwise condensation and preparation method of porous oil-filled metal surface

Abstract

The invention provides a porous oil-filled metal surface for strengthening dropwise condensation and a preparation method thereof, and the preparation method comprises the following steps: (1) processing a metal surface to form a blind hole array, and obtaining a porous surface; (2) polishing the porous surface to obtain a polished surface; (3) etching a nano structure on the polished surface to obtain a hydrophilic surface; (4) soaking the hydrophilic surface into a hydrophobic surface; and (5) infiltrating the hydrophobic surface into an oil-filled surface to obtain the porous oil-filled metal surface. The manufacturing method disclosed by the invention is simple and low in cost, can realize accelerated merging and rapid separation of the drop-shaped condensate drops on a plane and a curved surface, has a lasting drop-shaped condensation strengthening effect, can be suitable for a metal plate or a metal pipe, and is high in applicability and practicability; belongs to the technical field of heat transfer enhancement and energy conservation.

Description

Technical Field

[0001] The invention relates to the technical field of enhanced heat transfer and energy saving, and in particular to a porous oil-infused metal surface for enhanced droplet condensation and a preparation method thereof. Background Art

[0002] The phenomenon of steam condensation is widely present in the industrial field and nature. It is one of the important heat exchange processes in the fields of petrochemicals, power generation, energy and power, refrigeration and air conditioning, and energy conservation. The condensation mode of steam can be divided into film condensation and droplet condensation according to the degree of wetting between the condensate and the condensation surface. At present, there are two main methods to enhance condensation. One is film condensation, which is mainly to reduce the thickness of the surface condensate film, and the other is to change film condensation into droplet condensation through surface treatment. Droplet condensation is the most ideal way to enhance condensation heat transfer by using surface tension. Its condensation heat transfer coefficient is more than one order of magnitude higher than that of film condensation.

[0003] The oil-infused surface inspired by Nepenthes has an important application prospect in droplet condensation heat transfer and condensate collection because of its good condensation droplet migration ability. The basic design idea of ​​ordinary oil-infused surface is: first, prepare nanostructures on the solid surface; second, reduce the surface energy of the structure surface by treating with a hydrophobic solution; finally, immerse the surface in oil, and lock a layer of lubricating oil film through the low surface energy nanostructure, so as to permanently improve the movement and migration ability of droplets on the surface. Existing oil-infused surfaces can achieve enhanced droplet growth and merging. For example, the document "Robust platform for water harvesting and directional transport [J], Mater. Chem. A. 2018, 6, 5635" designed a wedge-shaped oil-infused surface to enhance droplet growth and merging, and the document "Condensation on slippery asymmetric bumps [J], Nature. 2016, 531: 78-82" designed a convex oil-infused surface to enhance droplet growth and merging. The above oil-infused surface structures have achieved certain results in promoting the merging of condensed droplets, but their preparation methods are complex and expensive, and they are difficult to implement on complex metal surfaces, which limits their application effects and scope. Therefore, it is of great value and significance to design an oil-infused surface with simple manufacturing methods, low cost, strong applicability and long-lasting droplet condensation enhancement effect. Summary of the invention

[0004] The purpose of the present invention is to provide a porous oil-infused metal surface for enhancing droplet condensation and a preparation method thereof, so as to solve the technical problems that the preparation method of the existing oil-infused surface for enhancing droplet growth and merging is complex and expensive, difficult to implement on complex metal surfaces, and has poor applicability.

[0005] To achieve the above object, the technical solution adopted by the present invention is: providing a method for preparing a porous oil-infused metal surface for enhancing droplet condensation, comprising the following steps:

[0006] (1) forming a blind hole array on the metal surface to obtain a porous surface;

[0007] (2) grinding the porous surface to obtain a grinded surface;

[0008] (3) etching nanostructures on the polished surface to obtain a hydrophilic surface;

[0009] (4) Soaking the hydrophilic surface into a hydrophobic surface;

[0010] (5) The hydrophobic surface is infiltrated into an oil-infused surface, thereby obtaining a porous oil-infused metal surface.

[0011] Preferably, in step (1), the metal includes any one of aluminum, aluminum alloy, and copper; and the metal surface includes a flat surface or a curved surface.

[0012] Preferably, in step (1), a laser marking machine is used to form a blind hole array on the metal surface, wherein the blind hole array is an array of multiple blind hole structures arranged at a fixed interval, the diameter D of the blind hole is 0.1≤D≤1mm, the depth H of the blind hole is 0.2≤H≤2mm, and the distance S between two adjacent blind holes is S>D.

[0013] In the present invention, the blind hole comprises a tapered blind hole.

[0014] Preferably, in step (1), after obtaining the porous surface, an acidic solution is used for ultrasonic cleaning to remove the residual metal powder and oxide layer in the blind holes on the porous surface, wherein the acidic solution comprises any one of dilute hydrochloric acid and dilute sulfuric acid, and the ultrasonic cleaning time is 30 to 90 seconds.

[0015] Preferably, in step (2), the porous surface is polished to be smooth using sandpapers of 1000 mesh, 1500 mesh, 2000 mesh and 3000 mesh in sequence.

[0016] In the present invention, the purpose of grinding is to ensure that the metal surface is flat and smooth and to prevent the metal surface from having protruding structures that interfere with condensation.

[0017] Preferably, in step (3), a chemical etching method is used to prepare the nanostructure on the polished surface.

[0018] Preferably, in step (3), for metallic aluminum and aluminum alloys, a hydrothermal synthesis method is used to prepare the nanostructure, and the hydrothermal synthesis time is 10 to 90 minutes; for metallic copper, a mixed aqueous solution of sodium hydroxide and ammonium persulfate is used to immerse the nanostructure, and the immersion time is 30 to 90 minutes.

[0019] In the present invention, the purpose of preparing the nanostructure is to better lock the silicone oil during subsequent infiltration of silicone oil and prevent the silicone oil from being lost too quickly.

[0020] Preferably, in step (4), the hydrophilic surface is treated into a hydrophobic surface using a hydrophobic solution, wherein the hydrophobic solution includes any one of a stearic acid solution and a fluorosilane solution. The specific operation is: soak the hydrophilic surface in the hydrophobic solution for 20 to 60 minutes, take it out, and then place the hydrophilic surface on a hot plate at 80 to 120° C. and heat it for 10 to 90 minutes to obtain a hydrophobic surface.

[0021] In the present invention, the hydrophobic solution may be selected from a 0.05 M stearic acid ethanol solution or a 1 mM 1H,1H,2H,2H-perfluorooctyltrichlorosilane n-hexane solution.

[0022] Preferably, in step (5), silicone oil is used to infiltrate the hydrophobic surface into an oil-infused surface, and the specific operation is: immersing the hydrophobic surface in silicone oil, taking it out after immersion, and then tilting it to stand still so that a uniform oil film layer is formed on its surface, thereby obtaining the oil-infused surface; wherein the viscosity of the silicone oil is 10 to 100 mPa·s, the immersion time is ≥30 min, and the tilted standing time is 1 to 12 h.

[0023] In the present invention, the purpose of tilting and standing is to allow excess silicone oil on the metal surface to flow away, and the remaining silicone oil is silicone oil locked in the nanostructure, and the oil film layer is relatively stable.

[0024] The present invention also provides a porous oil-infused metal surface for enhancing droplet condensation, which is prepared according to any of the above-mentioned methods for preparing a porous oil-infused metal surface for enhancing droplet condensation.

[0025] The present invention provides a porous oil-infused metal surface for strengthening droplet condensation and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects: the present invention processes a blind hole array on the metal surface, and the interior of the blind hole array structure has a lower water vapor diffusion flux, which can prevent water vapor from condensing and nucleating in the hole. The existence of the blind hole array also provides an energy barrier, so that the condensation droplets avoid the blind holes during the growth process, so the condensation droplets tend to move and merge in the plane between the blind holes, and the droplet condensation droplets are accelerated to merge and quickly detach; the present invention is not only applicable to metal planes, but also to metal curved surfaces, which improves the application effect and application range. The manufacturing method of the present invention is simple and low in cost, and can achieve the accelerated merging and rapid detachment of droplet condensation droplets on planes and curved surfaces, and has a persistent droplet condensation strengthening effect. It can be applied to metal plates or metal tubes, and has strong applicability and high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a morphology of the hydrophilic surface obtained during the preparation of the porous oil-infused metal surface of a 6061 aluminum alloy sheet in Example 1 of the present application;

[0028] Figure 2 The water drop contact angle on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 of the present application;

[0029] Figure 3 The sliding angle of a water droplet on the porous oil-infused metal surface of a 6061 aluminum alloy sheet prepared in Example 1 of the present application;

[0030] Figure 4 It is a diagram showing the condensation of water vapor on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 when placed horizontally for 60 minutes;

[0031] Figure 5 It is a curve diagram showing the change of the maximum condensed droplet diameter as a function of the condensation time when the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 are placed horizontally;

[0032] Figure 6It is a growth sequence diagram of condensed droplets on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 when placed vertically;

[0033] Figure 7 It is a graph showing the variation of the condensate droplet collection amount on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 as a function of condensation time;

[0034] Figure 8 This is a morphology of the hydrophilic surface obtained during the preparation of the porous oil-infused metal surface of a pure copper tube in Example 2 of the present application;

[0035] Fig. 9 It is a growth sequence diagram of condensed droplets on the porous oil-infused metal surface of the pure copper tube prepared in Example 2 and the ordinary oil-infused metal surface of the pure copper tube prepared in Comparative Example 2 when placed vertically. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercial products unless otherwise specified.

[0037] In order to verify the reliability of the effect of the present invention, the present invention is described below in conjunction with Examples 1 and 2, and compared with Comparative Examples 1 and 2.

[0038] Example 1

[0039] This embodiment provides a method for preparing a porous oil-infused metal surface for enhancing droplet condensation, comprising the following steps:

[0040] (1) preparing a 6061 aluminum alloy sheet of 20 mm × 40 mm × 2 mm, and using a laser marking machine to machine a tapered hole array with a diameter of 0.15 mm, a depth of 0.8 mm, and a mutual spacing of 0.5 mm on the surface of the 6061 aluminum alloy sheet to obtain a porous surface;

[0041] (2) Soaking the porous surface in 0.2 mol / L dilute hydrochloric acid for ultrasonic cleaning for 60 seconds to remove the residual metal powder in the blind holes on the porous surface and the oxide layer on the surface to obtain a clean porous surface;

[0042] (3) using 1000 mesh, 1500 mesh, 2000 mesh, and 3000 mesh sandpaper in sequence to grind the clean porous surface until it is smooth to obtain a grinded surface;

[0043] (4) Soaking the polished surface in boiling deionized water for 40 minutes to generate a nanostructure on the polished surface, then taking it out, waiting for the temperature of the polished surface to drop to room temperature and removing residual water to obtain a hydrophilic surface;

[0044] (5) soaking the hydrophilic surface in a 0.05 mol / L stearic acid ethanol solution for 60 min, then taking it out and heating it on a hot plate at 120° C. for 20 min to ensure that the stearic acid modifies the hydrophilic surface to obtain a hydrophobic surface;

[0045] (6) The hydrophobic surface was immersed in 10 mPa·s dimethyl silicone oil for 60 min, then taken out and tilted to stand for 2 h to form a uniform and stable oil film layer on its surface, thereby obtaining a porous oil-infused metal surface, which was named as 6061 aluminum alloy sheet porous oil-infused metal surface.

[0046] The hydrophilic surface prepared in step (4) of Example 1 was tested and its morphology was measured as follows: Figure 1 As shown. Figure 1 It can be seen that the hydrophilic surface is covered with rich nanosheet structures, which provides a guarantee for surface oil locking to form an oil-infused surface.

[0047] The wettability of the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 was characterized, and the contact angle and sliding angle of a water droplet (5 μL) on the porous oil-infused metal surface of the 6061 aluminum alloy sheet were measured as follows: Figure 2 and Figure 3 As shown. Figure 2 It can be seen that the contact angle of a water droplet (5 μL) on the porous oil-infused metal surface of a 6061 aluminum alloy sheet is 101°. Figure 3 It can be seen that the sliding angle of the droplet (5 μL) on the porous oil-infused metal surface of the 6061 aluminum alloy sheet is 3.5°. In summary, the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 has good hydrophobic properties.

[0048] In order to verify the effect of the present invention, the condensation performance of the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 was tested as follows:

[0049] Comparative Example 1

[0050] The present embodiment differs from Example 1 in that step (1) is not performed, i.e., the conical hole array is not punched on the surface of the 6061 aluminum alloy sheet, thereby obtaining a common oil-infused metal surface, which is named 6061 aluminum alloy sheet common oil-infused metal surface.

[0051] Condensation performance test method: Under the environmental conditions of humidity 49.1% RH and temperature 20°C, the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 were placed horizontally on a cold table with a base temperature of 1°C. The droplet condensation process was observed and photographed under a microscope. The results are shown in FIG. Figure 4-Figure 7 shown.

[0052] See also Figure 4 , is a diagram showing the condensation of water vapor on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 when placed horizontally for 60 minutes. Figure 4 It can be seen that the condensed droplets on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 are much larger than the condensed droplets on the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1. This shows that the condensed droplets are easier to move and merge on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1.

[0053] See also Figure 5 , is a graph showing the change of the maximum condensed droplet diameter with condensation time on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1. Figure 5 It can be seen that the maximum droplet size on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 is 1.7 times that of the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1, which shows that the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 has the effect of enhancing the growth and merging of droplets.

[0054] See also Figure 6 , which is a growth sequence diagram of condensed droplets on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1. Figure 6 It can be seen that if the two surfaces are placed vertically, the merged large droplets can more easily overcome the adhesion of the surface under the action of gravity, thereby accelerating the detachment of the condensed droplets and improving the condensation efficiency of the surface.

[0055] See also Figure 7 , is a graph showing the variation of the condensate droplet collection amount on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 and the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1 as a function of condensation time. Figure 7It can be seen that the amount of condensed water collected on the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 is much greater than that on the ordinary oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Comparative Example 1, which shows that the porous oil-infused metal surface of the 6061 aluminum alloy sheet prepared in Example 1 has stronger condensed water collection performance.

[0056] Example 2

[0057] This embodiment provides a method for preparing a porous oil-infused metal surface for enhancing droplet condensation, comprising the following steps:

[0058] (1) preparing a pure copper tube with an outer diameter of 10 mm and an inner diameter of 6 mm, and using a laser marking machine to machine an array of tapered holes with a diameter of 0.15 mm, a depth of 0.8 mm, and a mutual spacing of 0.5 mm on the outer surface of the pure copper tube to obtain a porous surface;

[0059] (2) Soaking the porous surface in 0.2 mol / L dilute hydrochloric acid for ultrasonic cleaning for 60 seconds to remove the residual metal powder in the blind holes on the porous surface and the oxide layer on the surface to obtain a clean porous surface;

[0060] (3) using 1000 mesh, 1500 mesh, 2000 mesh, and 3000 mesh sandpaper in sequence to grind the clean porous surface until it is smooth to obtain a grinded surface;

[0061] (4) soaking the polished surface in a mixed aqueous solution of 2.5 mol / L sodium hydroxide and 0.1 mol / L ammonium persulfate for 1 h to form a nano-copper oxide structure on the polished surface, then taking it out, waiting for the temperature of the polished surface to drop to room temperature and removing residual moisture to obtain a hydrophilic surface;

[0062] (5) soaking the hydrophilic surface in a 0.05 mol / L stearic acid ethanol solution for 30 min, then taking it out and heating it on a hot plate at 120° C. for 30 min to ensure that the stearic acid modifies the hydrophilic surface to obtain a hydrophobic surface;

[0063] (6) The hydrophobic surface was immersed in 10 mPa·s dimethyl silicone oil for 60 min, then taken out and tilted to stand for 2 h to form a uniform and stable oil film layer on its surface, thereby obtaining a porous oil-infused metal surface, which was named pure copper tube porous oil-infused metal surface.

[0064] The hydrophilic surface prepared in step (4) of Example 2 was tested and its morphology was measured as follows: Figure 8 As shown. Figure 8 It can be seen that the surface of the copper tube is covered with rich nano-sheet structures, which provides a guarantee for surface oil locking to form an oil-infused surface.

[0065] In order to verify the effect of the present invention, the condensation performance of the porous oil-infused metal surface of the pure copper tube prepared in Example 2 was tested as follows:

[0066] Comparative Example 2

[0067] The present implementation method is different from Example 2 in that step (1) is not performed, that is, the tapered hole array is not punched on the surface of the pure copper tube, thereby obtaining an ordinary oil-perfused metal surface, which is named pure copper tube ordinary oil-perfused metal surface.

[0068] Condensation performance test method: Under the environmental conditions of humidity 60% RH and temperature 26°C, the porous oil-infused metal surface of the pure copper tube prepared in Example 2 and the ordinary oil-infused metal surface of the pure copper tube prepared in Comparative Example 2 were simultaneously connected to the pipeline loop of a low-temperature water circulation box, and the circulating water temperature was 5°C. The droplet condensation process was observed and photographed by a SLR camera, and the results are shown as follows: Fig. 9 shown.

[0069] See also Fig. 9 , which is a growth sequence diagram of condensed droplets on the porous oil-infused metal surface of the pure copper tube prepared in Example 2 and the ordinary oil-infused metal surface of the pure copper tube prepared in Comparative Example 2. Fig. 9 It can be seen that the condensed droplets on the surface of the porous oil-infused metal of the pure copper tube prepared in Example 2 grow faster than the condensed droplets on the surface of the ordinary oil-infused metal of the pure copper tube prepared in Comparative Example 2, and more large condensed droplets appear below the surface of the porous oil-infused metal of the pure copper tube. This shows that the condensed droplets are easier to move and merge on the surface of the porous oil-infused metal of the pure copper tube prepared in Example 2.

[0070] Based on the condensation performance test results of Examples 1 to 2 and Comparative Examples 1 to 2, it can be seen that the porous oil-infused metal surface prepared by the present invention can achieve accelerated merging and rapid detachment of droplet-shaped condensation droplets on flat and curved surfaces, and has a persistent droplet-shaped condensation enhancement effect.

[0071] It should be noted that: in the above embodiments 1 to 2, in step (1), the diameter D of the blind hole is 0.1≤D≤1mm, the depth H of the blind hole is 0.2≤H≤2mm, and the distance S between two adjacent blind holes is S>D. In step (2), the acidic solution includes any one of dilute hydrochloric acid and dilute sulfuric acid, and the duration of ultrasonic cleaning is 30 to 90s. In step (4), for metal aluminum and aluminum alloy, the duration of hydrothermal synthesis is 10 to 90min; for metal copper, the immersion time is 30 to 90min. In step (5), the hydrophobic solution includes any one of stearic acid solution and fluorosilane solution, the immersion time of the hydrophilic surface in the hydrophobic solution is 20 to 60min, the temperature of the hot stage is 80 to 120°C, and the heating time is 10 to 90min. In step (6), the viscosity of the silicone oil is 10 to 100mPa·s, the immersion time is ≥30min, and the tilted static time is 1 to 12h. As long as the above parameters are within the range, they can be adaptively adjusted according to specific circumstances in actual production.

[0072] In summary, the present invention provides a porous oil-infused metal surface for enhancing droplet condensation and a preparation method thereof. Compared with the prior art, the present invention forms a blind hole array on the metal surface. The interior of the blind hole array structure has a lower water vapor diffusion flux, which can prevent water vapor from condensing and nucleating in the hole. The existence of the blind hole array also provides an energy barrier, so that the condensation droplets avoid the blind holes during the growth process, so the condensation droplets tend to move and merge in the plane between the blind holes, and the droplet condensation droplets are accelerated. Merge and quickly detach; the present invention is not only applicable to metal planes, but also to metal curved surfaces, which improves the application effect and scope of application. The manufacturing method of the present invention is simple and low-cost, and can achieve accelerated merging and rapid detachment of droplet condensation droplets on planes and curved surfaces, and has a persistent droplet condensation enhancement effect. It can be applied to metal plates or metal tubes, and has strong applicability and high practicality. The present invention can be widely used in the field of enhanced heat transfer and energy-saving technology.

[0073] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for preparing a porous oil-impregnated metal surface for enhanced droplet condensation, characterized in that: The following steps are involved: (1) forming a blind hole array on the metal surface to obtain a porous surface; (2) grinding the porous surface to obtain a grinded surface; (3) etching nanostructures on the polished surface to obtain a hydrophilic surface; (4) Soaking the hydrophilic surface into a hydrophobic surface; (5) The hydrophobic surface is infiltrated into an oil-infused surface, thereby obtaining a porous oil-infused metal surface.

2. The method for preparing a porous oil-impregnated metal surface for enhanced droplet condensation according to claim 1, characterized in that: In step (1), the metal includes any one of aluminum, aluminum alloy, and copper; and the metal surface includes a flat surface or a curved surface.

3. The method for preparing a porous oil-infused metal surface for enhanced droplet condensation according to claim 1, characterized in that: In step (1), a laser marking machine is used to form a blind hole array on the metal surface, wherein the blind hole array is an array of multiple blind hole structures arranged at a fixed interval, the diameter D of the blind hole is 0.1≤D≤1mm, the depth H of the blind hole is 0.2≤H≤2mm, and the distance S between two adjacent blind holes is S>D.

4. The method for preparing a porous oil-infused metal surface for enhanced droplet condensation according to claim 1, characterized in that: In step (1), after obtaining the porous surface, an acidic solution is used for ultrasonic cleaning to remove the residual metal powder and oxide layer in the blind holes on the porous surface. The acidic solution includes any one of dilute hydrochloric acid and dilute sulfuric acid. The ultrasonic cleaning time is 30 to 90 seconds.

5. The method for preparing a porous oil-infused metal surface for enhanced droplet condensation according to claim 1, characterized in that: In step (2), the porous surface is polished to be smooth using sandpapers of 1000 mesh, 1500 mesh, 2000 mesh, and 3000 mesh in sequence.

6. The method for preparing a porous oil-infused metal surface for enhanced droplet condensation according to claim 2, characterized in that: In step (3), a nanostructure is prepared on the polished surface using a chemical etching method.

7. The method for preparing a porous oil-impregnated metal surface for enhanced droplet condensation according to claim 6, characterized in that: In step (3), for metallic aluminum and aluminum alloy, a hydrothermal synthesis method is used to prepare a nanostructure, and the hydrothermal synthesis time is 10 to 90 minutes; for metallic copper, a mixed aqueous solution of sodium hydroxide and ammonium persulfate is used to immerse the nanostructure, and the immersion time is 30 to 90 minutes.

8. The method for preparing a porous oil-infused metal surface for enhanced droplet condensation according to claim 1, characterized in that: In step (4), the hydrophilic surface is treated into a hydrophobic surface using a hydrophobic solution, wherein the hydrophobic solution includes any one of a stearic acid solution and a fluorosilane solution. The specific operation is: the hydrophilic surface is immersed in the hydrophobic solution for 20 to 60 minutes, taken out, and then the hydrophilic surface is placed on a hot plate at 80 to 120° C. and heated for 10 to 90 minutes to obtain a hydrophobic surface.

9. The method for preparing a porous oil-impregnated metal surface for enhanced droplet condensation according to claim 1, characterized in that: In step (5), silicone oil is used to infiltrate the hydrophobic surface into an oil-infused surface. The specific operation is: immerse the hydrophobic surface in silicone oil, take it out after immersion, and then tilt it to stand still so that a uniform oil film layer is formed on its surface, thereby obtaining the oil-infused surface; wherein the viscosity of the silicone oil is 10 to 100 mPa·s, the immersion time is ≥30 min, and the tilted standing time is 1 to 12 h.

10. A porous oil-impregnated metal surface for enhanced droplet condensation, characterized in that: The surface is prepared by the method for preparing a porous oil-infused metal surface for enhancing droplet condensation according to any one of claims 1 to 9.

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