Water desalination device and method of making same

Abstract

The application provides a water desalination device and a manufacturing method thereof. The device comprises a shell; evaporation units and condensation units in parallel wave crest and trough are staggered in the shell, and the evaporation units are provided with the condensation units at both ends; the evaporation unit comprises an optical absorption layer and an evaporation surface, a transparent anti-convection cover is arranged above the optical absorption layer, the anti-convection cover is fixed on the upper surface of the shell, the upper and lower surfaces of the V-shaped structure are respectively arranged on the upper and lower parts of the optical absorption layer and the evaporation surface, and the lower end of the evaporation surface is inserted into a water tank for evaporation; the condensation unit comprises a cooling side and a condensation side, the cooling side and the condensation side are respectively arranged on the upper and lower sides of the upper surface of the shell, the cooling side comprises a plurality of 3D fins coated with a radiation refrigeration coating, and the condensation side comprises a plurality of hydrophobic copper columns; the water tank for evaporation is provided with a water inlet; the liquid drops of the condensation side are gathered at the bottom of the shell; and the bottom of the shell is provided with a water outlet. The application can effectively alleviate the fresh water crisis problem in energy shortage areas.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a water desalination device and its manufacturing method. Background Technology

[0002] Water is a fundamental element for human survival. Despite the Earth's abundant water resources, the lack of safe drinking water remains a significant challenge. Traditional water treatment methods (such as evaporation and membrane filtration) often consume large amounts of fossil fuels. With the advancement of the "dual carbon" goal, there is a strong need to develop freshwater collection technologies based on renewable energy sources. Therefore, green and clean freshwater collection or treatment technologies have become one of the urgent tasks in solving the water shortage problem. In the past few years, researchers have made numerous efforts to overcome this problem, including wastewater filtration, mist collection, air-based water collection, and photothermal evaporation. Freshwater collection technology based on photothermal evaporation has shown great potential in water treatment processes such as freshwater collection due to its high evaporation efficiency, simple structure, and low cost, attracting great interest from scholars both domestically and internationally. However, the mutual constraints and inability to achieve synchronous matching between the evaporation and condensation ends result in an actual freshwater collection rate that is far lower than the evaporation rate, severely limiting its large-scale practical application. Therefore, how to decouple the evaporation and condensation ends to improve the system's freshwater collection rate is of great significance. Summary of the Invention

[0003] The present invention provides a water desalination device and its manufacturing method, the purpose of which is to solve the above-mentioned problems existing in the background art.

[0004] To achieve the above objectives, embodiments of the present invention provide a water desalination device and its manufacturing method. The device employs a heat pipe-like structure to decouple the light-absorbing layer and evaporation surface of the evaporation unit, and the cooling side and condensation side of the condensation unit. Specifically, a flexible, foldable, light-thermal selective absorption coating (light-absorbing layer) is controllably prepared in the light-absorbing layer of the evaporation unit through a displacement reaction, achieving a solar light absorption rate of up to [percentage missing]. Mid-infrared emissivity as low as The coupled convection barrier significantly improves the light-to-heat conversion efficiency on the light-absorbing side; on the evaporation surface of the evaporation unit, copper foam is modified by oxidation and in-situ polymerization to give it a high resistance to gravitational water transport rate (0.042 ms). -1 With a lower enthalpy of vaporization (1297 J g) -1 This effectively improves its evaporation rate. By folding the light-absorbing layer and the evaporation surface into a V-shaped three-dimensional structure, its evaporation rate can reach 4.31 kg / m³ under 1x light intensity. -2 h -1The evaporation rate is high. On the cooling side of the condensing unit, a radiative cooling coating is applied to the surface of a three-dimensional finned structure, coupling daytime passive radiative cooling with natural convection cooling. Its temperature drop is 3.5℃ lower than that of a single flat substrate (under the same heat source). On the condensing side of the condensing unit, a copper pillar array structure is set up and modified to be hydrophobic (142°), improving the condensation of steam and the shedding of droplets. Under indoor light intensity of 1 times the normal value, the device can achieve a freshwater collection rate of 2.06 kg / m³. -2 h -1 Outdoor freshwater collection rate up to 2.34 kg / m³ -2 h -1 The passive freshwater collection strategy designed in this invention makes full use of solar energy and space cold energy to achieve efficient passive freshwater collection, which can effectively alleviate the freshwater crisis in energy-scarce areas.

[0005] One object of embodiments of the present invention is to provide a water desalination device.

[0006] Includes the casing;

[0007] The shell contains evaporation units and condensation units arranged in parallel with peaks and troughs, and condensation units are provided at both ends of the evaporation units.

[0008] The evaporation unit includes a light-absorbing layer and an evaporation surface. A transparent anti-convection cover is provided above the light-absorbing layer and is fixedly installed on the upper surface of the shell. The upper part of the light-absorbing layer and the evaporation surface are respectively provided on the upper and lower surfaces of the V-shaped structure. The lower end of the evaporation surface is inserted into the evaporation water tank.

[0009] The condensation unit includes a cooling side and a condensation side, which are respectively disposed on the upper and lower sides of the upper surface of the housing. The cooling side includes multiple 3D fins coated with a radiation cooling coating, and the condensation side includes multiple hydrophobic copper pillars.

[0010] The evaporation water tank is equipped with a water inlet; the droplets on the condensation side collect at the bottom of the shell; and the bottom of the shell is equipped with a water outlet.

[0011] According to one aspect of an embodiment of the present invention, the included angle of the V-shaped structure is 30°, the height is 1.7cm, the width is 2cm, and the thickness of the lower end of the evaporation surface is 1mm.

[0012] According to one aspect of an embodiment of the present invention, the water includes seawater and wastewater.

[0013] According to one aspect of an embodiment of the present invention, the solar absorption rate of the light-absorbing layer Up to 0.92, mid-infrared emissivity As low as 0.1.

[0014] According to one aspect of an embodiment of the present invention, the antigravity water transport rate of the evaporation surface is 0.042 ms. -1 Enthalpy of evaporation 1297 J g -1 .

[0015] According to one aspect of an embodiment of the present invention, the hydrophobic angle of the copper pillar is 142°.

[0016] According to one aspect of an embodiment of the present invention, the number of evaporation units is at least one set or at least two sets.

[0017] Another objective of the embodiments of the present invention is to provide a method for manufacturing the above-mentioned passive freshwater collection device, comprising the following steps: preparing the shell using 3D printing;

[0018] The upper and lower surfaces of a 30°, 1.7cm high V-shaped structure are respectively attached to the light-absorbing layer and the upper part of the evaporation surface. The lower end of the evaporation surface is inserted into the evaporation water tank, and a transparent anti-convection cover is fixed above the light-absorbing layer.

[0019] The condenser side is connected to the 3D fins coated with a radiation cooling coating via thermally conductive adhesive, and is located on the upper and lower sides of the upper surface of the shell.

[0020] Preparation of light-absorbing layer:

[0021] Cut the zinc sheet into pieces, ultrasonically clean the zinc sheet with alcohol, air dry it, and simply immerse it in dilute sulfuric acid to remove the surface oxide layer. Then immerse it in CuSO4 solution, take it out, rinse it, and air dry it.

[0022] Preparation of evaporation surface:

[0023] Copper foam was modified by oxidation and in-situ polymerization to obtain copper / copper oxide-polypyrrole foam;

[0024] Preparation of radiation-cooled coating:

[0025] Take the thickener solution and mix it with hollow glass microspheres, then add styrene-butadiene rubber latex and ultrasonically disperse it into a uniform slurry. Let it stand to remove air bubbles, then coat the slurry onto an acrylic plate and dry it to obtain the final product.

[0026] Preparation of the condenser side:

[0027] The copper column array is placed in mixed solution 1, heated in a constant temperature water bath, rinsed with deionized water and dried, then immersed in mixed solution 2, and finally dried to obtain the final product.

[0028] According to one aspect of an embodiment of the present invention, the preparation process of the condenser side is specifically as follows: the copper column array is placed in a mixed solution of NaClO2, NaOH, Na3PO4·12H2O and deionized water in a mass fraction of 3.75:5:10:100, heated in a water bath at a constant temperature of 95°C for 10 minutes, removed, rinsed with deionized water and dried, and then immersed in a mixed solution of 1H,1H,2H,2H-perfluorooctyltrichlorosilane and alcohol in a mass fraction of 1:100 for 3 minutes, removed and dried to obtain the final product.

[0029] According to one aspect of the present invention, the process of preparing the evaporation surface is as follows: NaClO2, NaOH, Na3PO4·12H2O and deionized water are mixed in a mass fraction of 3.75:5:10:100 to prepare a mixed solution, which is placed in a constant temperature water bath at 95°C. The copper foam is immersed in the mixed solution for 10 minutes, and then removed and dried to obtain copper / copper oxide foam.

[0030] Dissolve 2.74 g of (NH4)2S2O8 in 5 mL of deionized water and label it as monomer A;

[0031] Mix 0.84 mL of pyrrole with 5 mL of isopropanol (IPA) and 1.84 mL of phytic acid solution, and label the mixture as monomer B.

[0032] Then monomers A and B are sprayed alternately onto the copper / copper oxide foam in the order BABA to obtain copper / copper oxide-polypyrrole foam.

[0033] According to one aspect of an embodiment of the present invention, the thickener solution is obtained by dissolving 1g of sodium carboxymethyl cellulose (CMCNa) in 75g of water and stirring at 80°C for 1 to 2 hours.

[0034] The working principle is as follows:

[0035] Copper / copper oxide-polypyrrole foam, with excellent anti-gravity water transport performance and low enthalpy of vaporization, overcomes gravity to supply water through capillary force. Combined with a light-absorbing layer, it heats the wastewater on the evaporation surface to generate water vapor. The convection shielding layer (transparent PE film) covering the light-absorbing layer reduces non-radiative losses, allowing water vapor to be transported from the evaporation unit to the condensation unit through natural convection. The hydrophobic copper pillar array on the condensation side improves steam condensation and droplet shedding. The daytime radiation cooling coating on the cooling side, combined with the finned heat sink, further enhances the passive cooling performance. The 3D-printed shell and the staggered evaporation-condensation structure with parallel crests and troughs further reduce the steam transport resistance in the confined space, thereby improving the passive freshwater collection performance.

[0036] The above-described solution of the present invention has the following beneficial effects:

[0037] (1) This invention, through a decoupled design of evaporation and condensation, couples passive heating and cooling. Under indoor light intensity of 1 times the normal intensity, the device can achieve a freshwater collection rate of 2.06 kg / m³. -2 h -1 Outdoor freshwater collection rate up to 2.34 kg / m³ -2 h -1 .

[0038] (2) Compared with freshwater collection and treatment methods such as reverse osmosis, multi-stage flash evaporation and electrodialysis, this invention makes full use of solar energy and space cold energy to achieve efficient passive freshwater collection, which has extremely high environmental and economic value and provides a new idea for obtaining sustainable water resources in arid or water-scarce areas. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a front view of the overall structure of a water desalination device according to the present invention;

[0041] Figure 2 This is a front view of a water desalination device according to the present invention;

[0042] [Explanation of Labels in the Attached Image]

[0043] 1-Shell; 2-Cooling side; 3-Condensation side; 4-Anti-convection cover; 5-Light-absorbing layer; 6-Evaporation surface; 7-Evaporation water tank; 8-Water outlet. Detailed Implementation

[0044] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0045] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0046] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0047] To address the existing problems, one objective of embodiments of the present invention is to provide a water desalination device.

[0048] Includes housing 1;

[0049] The shell 1 contains evaporation units and condensation units arranged in parallel with peaks and valleys, and condensation units are provided at both ends of the evaporation units.

[0050] The evaporation unit includes a light-absorbing layer 5 and an evaporation surface 6. A transparent anti-convection cover 4 is provided above the light-absorbing layer 5. The anti-convection cover 4 is fixedly provided on the upper surface of the shell 1. The upper ends of the light-absorbing layer 5 and the evaporation surface 6 are respectively provided on the upper and lower surfaces of the V-shaped structure. The lower end of the evaporation surface 6 is inserted into the evaporation water tank 7.

[0051] The condensation unit includes a cooling side 2 and a condensation side 3, which are respectively disposed on the upper and lower sides of the upper surface of the housing 1. The cooling side 2 includes multiple 3D fins coated with a radiation cooling coating, and the condensation side 3 includes multiple hydrophobic copper pillars.

[0052] The evaporation water tank 7 is provided with a water inlet; the droplets on the condensation side 3 collect at the bottom of the shell 1; and the bottom of the shell 1 is provided with a water outlet 8.

[0053] According to one aspect of an embodiment of the present invention, the included angle of the V-shaped structure is 30°, the height is 1.7cm (the vertical distance between the lowest and highest points of the "V"), and the width is 2cm (the widest point); the thickness of the lower end of the evaporation surface 6 is 1mm.

[0054] According to one aspect of an embodiment of the present invention, the water includes seawater and wastewater.

[0055] According to one aspect of an embodiment of the present invention, the solar absorption rate of the light-absorbing layer 5 is... Up to 0.92, mid-infrared emissivity As low as 0.1.

[0056] According to one aspect of an embodiment of the present invention, the antigravity water transport rate of the evaporation surface 6 is 0.042 ms. -1 Enthalpy of evaporation 1297 J g -1 .

[0057] According to one aspect of an embodiment of the present invention, the hydrophobic angle of the copper pillar is 142°.

[0058] According to one aspect of an embodiment of the present invention, the number of evaporation units is at least one set or at least two sets.

[0059] Another objective of the embodiments of the present invention is to provide a method for manufacturing the above-mentioned passive freshwater collection device, comprising the following steps: fabricating the shell 1 using 3D printing;

[0060] The light-absorbing layer 5 and the upper end of the evaporation surface 6 are respectively attached to the upper and lower surfaces of the V-shaped structure, and the lower end of the evaporation surface 6 is inserted into the evaporation water tank 7. A transparent anti-convection cover 4 is fixed above the light-absorbing layer 5.

[0061] The condenser side 3 is connected to the 3D fins coated with a radiation cooling coating via thermally conductive adhesive and is located on the upper and lower sides of the upper surface of the housing 1.

[0062] Preparation of light-absorbing layer 5:

[0063] Cut the zinc sheet into pieces, ultrasonically clean the zinc sheet with alcohol, air dry it, and simply immerse it in dilute sulfuric acid to remove the surface oxide layer. Then immerse it in CuSO4 solution, take it out, rinse it, and air dry it.

[0064] Preparation of evaporation surface 6:

[0065] Copper foam was modified by oxidation and in-situ polymerization to obtain copper / copper oxide-polypyrrole foam;

[0066] Preparation of radiation-cooled coating:

[0067] Take the thickener solution and mix it with hollow glass microspheres, then add styrene-butadiene rubber latex and ultrasonically disperse it into a uniform slurry. Let it stand to remove air bubbles, then coat the slurry onto an acrylic plate and dry it to obtain the final product.

[0068] Preparation of condenser side 3:

[0069] The copper column array is placed in mixed solution 1, heated in a constant temperature water bath, rinsed with deionized water and dried, then immersed in mixed solution 2, and finally dried to obtain the final product.

[0070] According to one aspect of an embodiment of the present invention, the preparation process of the condenser side 3 is specifically as follows: the copper column array is placed in a mixed solution of NaClO2, NaOH, Na3PO4·12H2O and deionized water in a mass fraction of 3.75:5:10:100, heated in a water bath at a constant temperature of 95°C for 10 minutes, removed, rinsed with deionized water and dried, and then immersed in a mixed solution of 1H,1H,2H,2H-perfluorooctyltrichlorosilane and alcohol in a mass fraction of 1:100 for 3 minutes, removed and dried to obtain the final product.

[0071] According to one aspect of an embodiment of the present invention, the process of preparing the evaporation surface 6 is as follows: take NaClO2, NaOH, Na3PO4·12H2O and deionized water to prepare a mixed solution with a mass fraction of 3.75:5:10:100, place it in a constant temperature water bath at 95°C, immerse the foamed copper in the mixed solution for 10 minutes, take it out and dry it to obtain copper / copper oxide foam;

[0072] Dissolve 2.74 g of (NH4)2S2O8 in 5 mL of deionized water and label it as monomer A;

[0073] Mix 0.84 mL of pyrrole with 5 mL of isopropanol (IPA) and 1.84 mL of phytic acid solution, and label the mixture as monomer B.

[0074] Then monomers A and B are sprayed alternately onto the copper / copper oxide foam in the order BABA to obtain copper / copper oxide-polypyrrole foam.

[0075] According to one aspect of an embodiment of the present invention, the thickener solution is obtained by dissolving 1g of sodium carboxymethyl cellulose (CMCNa) in 75g of water and stirring at 80°C for 1 to 2 hours.

[0076] The following examples illustrate this in detail.

[0077] Example 1

[0078] A method for manufacturing a water desalination device includes the following steps:

[0079] Preparation of S1, the light-absorbing layer 5: First, a 0.01 mol / L CuSO4 solution was placed in a constant temperature water bath and the temperature was adjusted to 75°C. Then, zinc sheets were cut into blocks, and tape was applied to one side to ensure uniformity during the displacement reaction. Subsequently, the zinc sheets were ultrasonically cleaned in alcohol for five minutes, then dried and simply immersed in dilute sulfuric acid to remove the surface oxide layer. The cleaned zinc sheets were immersed in the solution for 60 seconds, then removed, rinsed, and dried.

[0080] Preparation process of S2, evaporation surface 6: Preparation process of porous metal foam copper / copper oxide-polypyrrole: Prepare a mixed solution of NaClO2, NaOH, Na3PO4·12H2O and deionized water (3.75:5:10:100wt%), then place it in a constant temperature water bath at 95℃. Immerse the copper foam in the mixed solution for 10 minutes, remove and dry to obtain copper / copper oxide foam. Dissolve 2.74g (NH4)2S2O8 in 5mL of deionized water and label it as monomer A. Mix 0.84mL of pyrrole with 5mL of isopropanol (IPA) and 1.84mL of phytic acid solution and label it as monomer B. Then, alternately spray monomers A and B onto the copper / copper oxide foam in the order BABA to obtain copper / copper oxide-polypyrrole foam.

[0081] S3, Preparation process of the radiation-cooling coating: The radiation-cooling coating was prepared using commercially available hollow glass microspheres (3M's iM30K). First, the thickener solution was obtained by dissolving 1g of sodium carboxymethyl cellulose (CMCNa) in 75g of water and stirring at 80°C for 1-2 hours. Then, 14g of the thickener solution was mixed with 6g of hollow glass microspheres to form a white slurry. Next, 1g of styrene-butadiene rubber (SBR) emulsion was added to the white slurry as a binder. Finally, the mixture was treated with an ultrasonic cell disruptor for 2-3 minutes to form a uniformly dispersed slurry. After standing for 12 hours to remove air bubbles, the slurry was coated onto an acrylic plate and then dried in an oven to obtain the radiation-cooling coating.

[0082] S4, the process of surface modification of the condenser side 3: A three-dimensional copper heat sink is placed in a mixed solution of NaClO2, NaOH, Na3PO4·12H2O, and deionized water (3.75:5:10:100wt%), heated in a constant temperature water bath at 95℃ for 10 minutes, and then removed. After rinsing with deionized water and drying, it is immersed in a mixed solution of 1H,1H,2H,2H-perfluorooctyltrichlorosilane and alcohol (1:100wt%) for 3 minutes, then removed and dried to obtain the hydrophobic condenser side 3.

[0083] S5. The designed device is printed using a 3D printer. The light-absorbing layer 5 is folded into a paper-folding structure consisting of three 30° V-shapes, each 1.7cm high and 2cm wide. Six copper / copper oxide-polypyrrole foams are folded and glued to the back of the light-absorbing layer 5 to obtain the evaporation surface 6. The entire assembly is then placed in the evaporation water tank 7. Finally, a transparent PE film is placed over the light-absorbing layer 5 to reduce heat convection loss. The three-dimensional hydrophobic copper pillar condenser side 3 is placed inside the housing 1. Thermally conductive adhesive is applied to the back of the three-dimensional hydrophobic copper pillar condenser side 3, and a three-dimensional aluminum heat sink coated with a radiation cooling coating is placed on top. Deionized water is then added through the communicating vessel connected to the evaporation water tank 7. A container is placed next to the outlet 8 on the condenser side 3 to collect the generated fresh water.

[0084] Comparative Example 1

[0085] A water desalination device consists of a set of evaporation units and a set of condensation units symmetrically distributed within a shell. Other components and manufacturing parameters are the same as in Example 1.

[0086] To better demonstrate the freshwater collection performance of the device, Comparative Example 1 was set as the control group, and the specific experiments included the following:

[0087] (1) Three-dimensional reverse evaporation experiment

[0088] A solar xenon lamp simulator was used to simulate sunlight, and a solar radiometer was used to calibrate the solar intensity to 1000 W / m². -2In a planar evaporator configuration, the evaporation performance was compared using cotton cloth and copper / copper oxide-polypyrrole foam. The entire evaporation system was placed on an electronic balance, and a computer was connected to record the continuous mass changes of the evaporation system. In the planar evaporator configuration, copper / copper oxide-polypyrrole foam exhibited excellent mass transfer behavior during evaporation, with an evaporation rate of 1.73 kg m³ / h. -2 h -1 ) higher than cotton cloth (1.14 kg m -2 h -1 ).

[0089] Furthermore, a folded 3D structure evaporator is introduced, in which the light-absorbing layer 5 is folded into a V-shape. Two copper / copper oxide-polypyrrole foams are folded and pasted onto the back of the light-absorbing layer 5, and the entire assembly is inserted into the insulating foam. The ends of the copper / copper oxide-polypyrrole foams penetrate the foam and contact the water in the evaporation tank 7 (i.e., the evaporation unit of this invention). To optimize the V-shaped structure, parameters such as the folding angle, foam thickness, and height / width were fine-tuned. With a fixed width of 2 cm and a foam thickness of 1 mm, the evaporation rate initially increases with the increase of the folding angle due to the increase in evaporation area, but eventually decreases due to insufficient water supply. At this point, the optimal folding angle is 30°, and the peak evaporation rate is 2.92 kg m³. -2 h -1 With a fixed folding angle of 30° and a width of 2cm, further optimization revealed that a foam thickness of 1mm yielded the best results. In other cases, for example, thinner foam (0.5mm) resulted in insufficient water supply, while thicker foam (2mm) increased the heat transfer resistance between the solar thermal interface and the evaporator.

[0090] (2) Salt resistance test of evaporation surface 6

[0091] During water evaporation, if salt residue forms scale on the surface of the evaporation layer, it will reduce heat transfer efficiency and thus affect the evaporation rate. Therefore, the evaporation performance of evaporation surface 6 in brine was evaluated. In 3.5 wt% brine, after evaporation surface 6 operated continuously for 9 hours, the evaporation rate decreased slightly. This is because as the evaporation process proceeds, the water content in the evaporation layer decreases, the salt concentration increases, leading to the formation of salt crystals on the surface of the evaporation layer. Nevertheless, the evaporation rate can still be maintained between 3.72 and 4.35 kg m³. -2 h -1The study demonstrated the potential for long-term stable desalination. A scenario was also simulated where salt particles were sprinkled onto evaporation surface 6, and the simulated light source was then turned off. Under dark conditions with the light source off, the salt particles on evaporation surface 6 dissolved and diffused back into the bottom water within 40 minutes. This is because the copper / copper oxide-polypyrrole foam has a three-dimensional porous structure that promotes salt diffusion and reflux. Simultaneously, in darkness, water evaporation slows down, reducing the salt gradient between evaporation surface 6 and the bottom water, causing the crystalline salt to dissolve and return to the bottom water. This indicates that even after long-term water evaporation and salt accumulation, the salt particles can diffuse back into the bottom water, effectively preventing salt buildup.

[0092] (3) Steam condensation experiment on the condenser side

[0093] To evaluate the water collection performance of condenser side 3, the sample was placed in a constant temperature and humidity chamber, with the internal temperature controlled at 25℃ and humidity at 99%. A humidifier was used to simulate the generation of steam during water evaporation to test the water collection performance. To further improve the water collection capacity, a copper column array was prepared to expand the condensation specific area. The original smooth surface of copper was chemically etched into knife-shaped nanosheets. Simultaneously, after oxidation modification, it was treated with PFOTS for 3 minutes to obtain a hydrophobic surface. The contact angle of the copper significantly increased from 88° to 142°, indicating that the hydrophobic nano-copper oxide surface has good hydrophobicity. The water collection experiment results show that the water collection rate of the three-dimensional hydrophobic condenser side 3 can reach 3.05 kg m³. -2 h -1 It is far higher than the two-dimensional hydrophilic condensation side (1.32 kg m -2 h -1 ) and two-dimensional hydrophobic condensation side (1.56 kg m -2 h -1 Furthermore, the water collection performance of the three-dimensional hydrophobic condensation side 3 under different subcooling degrees was further evaluated using a cryogenic constant temperature bath. As the subcooling degree increased from 0℃ to 10℃, the water collection rate increased from 3.02 kg / m³. -2 h -1 Increased to 5.72 kg m -2 h -1 These results demonstrate that adjusting the subcooling, wettability, and geometry of the condenser side has a significant impact on passive freshwater collection. Condensation performance was further enhanced by combining passive cooling strategies, structural optimization, and alteration of wettability.

[0094] (4) Passive cooling performance test on the condenser side 3

[0095] To evaluate the cooling performance of condenser side 3, an outdoor temperature drop experiment was conducted on the cooling layer separately outdoors. To compare the cooling effects, four samples were placed: a two-dimensional aluminum plate, a two-dimensional aluminum plate coated with a radiation-cooling coating, a three-dimensional aluminum radiator, and another three-dimensional aluminum radiator coated with a radiation-cooling coating. For photothermal evaporation desalination systems, the operating temperature of condenser side 3 is often higher than the ambient temperature. Therefore, a DC power supply and a heating plate were used to simulate a heat source environment. At 300W m -2 Under the heat source, the three-dimensional finned aluminum radiator covered with a radiation cooling coating achieved the lowest temperature rise (~13°C). This is significantly lower than the temperature rise of the two-dimensional aluminum plate coated with a radiation cooling coating (~16.5°C), the three-dimensional finned aluminum radiator without a radiation cooling coating (~19.5°C), and the two-dimensional aluminum plate without a radiation cooling coating (~24.4°C).

[0096] At temperatures below ambient, thermal convection must be avoided to minimize heat gain from the air. Therefore, planar substrates with a radiative cooling coating achieve the highest temperature drop (~3.2°C). Based on the achieved performance, it exhibits maximum cooling performance when the fin structure is combined with the radiative cooling coating and thermal convection design, given that the device operates at temperatures above ambient.

[0097] (5) Indoor freshwater collection performance test

[0098] To improve water production, an optimized evaporation surface 6 and condensation side 3 were combined to form a three-dimensional inverted freshwater collection device based on photothermal and radiative cooling. Indoor water production experiments were conducted to evaluate the freshwater collection performance of the entire device, recording the change in water production over time under 1 times the light intensity. Under one solar condition, the average water collection volume over 6 consecutive hours was 2.02 kg m³. -2 h -1 It covers the indoor evaporation rate (4.31 kg m³). -2 h -1 48% of the simulated solar intensity. When the simulated solar intensity increases from 0.5 solar units to 1.5 solar units, the water collection rate increases from 0.95 kg / m³. -2 h -1 Increased to 2.99 kg m -2 h -1 .

[0099] (6) Outdoor Freshwater Collection Experiment

[0100] To further evaluate its water production performance in practical applications, evaporation was carried out using natural sunlight as the heat source and condensation using outer space as the cold source. On sunny days, solar intensity and ambient temperature fluctuated over time. Initially, due to the lack of steam evaporation, the temperature on condensation side 3 was lower than the ambient temperature. As time progressed, water vapor continued to be generated and condensed, and the temperature on condensation side 3 rose above the ambient temperature. The water collection rate was highly dependent on solar intensity, starting from 0 kg / m³ at sunrise. -2 h -1 The temperature rose to 2.34 kg / m at 2 PM. -2 h -1 The peak solar intensity was 952W. -2 It gradually decreased to 0.41 kg m by sunset. -2 h -1 .

[0101] During the 5-day water collection experiment, the average water collection rate measured ranged from 1.21 to 1.85 kg / m³. -2 h -1 This fully passive, heat pipe-inspired freshwater harvesting device achieves a yield of approximately 1.85 kg m³ by utilizing solar energy and a cold source from outer space. -2 h -1 Its high efficiency in water collection.

[0102] For a device where the evaporation and condensation units are symmetrically distributed within the shell—Comparative Example 1—an indoor water production experiment was also conducted to evaluate the freshwater collection performance of the entire device. The change in water production over time was recorded under 1 times the light intensity, with a production rate of 1.03 kg / m³. -2 h -1 Outdoor water production experiments also showed that, at a peak solar intensity of approximately 877 Wm... -2 At that time, its peak water production was 1.02 kg m³. -2 h -1 The indoor and outdoor freshwater collection performance is far inferior to that of the desalination device described in this invention.

[0103] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A water desalination device, characterized in that, Includes the casing; The shell contains evaporation units and condensation units arranged in parallel with peaks and troughs, and condensation units are provided at both ends of the evaporation units. The evaporation unit includes a light-absorbing layer and an evaporation surface. A transparent anti-convection cover is provided above the light-absorbing layer and is fixedly installed on the upper surface of the shell. The upper part of the light-absorbing layer and the evaporation surface are respectively provided on the upper and lower surfaces of the V-shaped structure. The lower end of the evaporation surface is inserted into the evaporation water tank. The condensation unit includes a cooling side and a condensation side, which are respectively disposed on the upper and lower sides of the upper surface of the housing. The cooling side includes multiple 3D fins coated with a radiation cooling coating, and the condensation side includes multiple hydrophobic copper pillars. The evaporation water tank is equipped with a water inlet; the droplets on the condensation side collect at the bottom of the shell; and the bottom of the shell is equipped with a water outlet.

2. The water desalination device according to claim 1, characterized in that, The included angle of the V-shaped structure is 30°, the height is 1.7cm, and the width is 2cm; the thickness of the lower end of the evaporation surface is 1mm.

3. The water desalination device according to claim 1, characterized in that, The solar absorption rate of the light-absorbing layer Up to 0.92, mid-infrared emissivity As low as 0.

1.

4. The water desalination device according to claim 1, characterized in that, The anti-gravity water transport rate of the evaporation surface is 0.042 ms. -1 Enthalpy of evaporation 1297 J g -1 .

5. A water desalination device according to claim 1, characterized in that, The hydrophobic angle of the copper pillar is 142°.

6. The water desalination device according to claim 1, characterized in that, The number of evaporation units is at least one set or at least two sets.

7. A method for manufacturing a water desalination device as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The shell is manufactured using 3D printing; The light-absorbing layer and the upper part of the evaporation surface are respectively attached to the upper and lower surfaces of the V-shaped structure, and the lower end of the evaporation surface is inserted into the evaporation water tank. A transparent anti-convection cover is fixed above the light-absorbing layer. The condenser side is connected to the 3D fins coated with a radiation cooling coating via thermally conductive adhesive, and is located on the upper and lower sides of the upper surface of the shell. Preparation of light-absorbing layer: Cut the zinc sheet into pieces, ultrasonically clean the zinc sheet with alcohol, air dry it, and simply immerse it in dilute sulfuric acid to remove the surface oxide layer. Then immerse it in CuSO4 solution, take it out, rinse it, and air dry it. Preparation of evaporation surface: Copper foam was modified by oxidation and in-situ polymerization to obtain copper / copper oxide-polypyrrole foam; Preparation of radiation-cooled coating: Take the thickener solution and mix it with hollow glass microspheres, then add styrene-butadiene rubber latex and ultrasonically disperse it into a uniform slurry. Let it stand to remove air bubbles, then coat the slurry onto an acrylic plate and dry it to obtain the final product. Preparation of the condenser side: The specific process for preparing the condenser side is as follows: The copper column array is placed in a mixed solution 1 prepared with NaClO2, NaOH, Na3PO4·12H2O and deionized water in a mass fraction of 3.75:5:10:

100. The solution is heated in a water bath at a constant temperature of 95°C for 10 minutes. After being removed, it is rinsed with deionized water and dried. Then, it is immersed in a mixed solution 2 prepared with 1H,1H,2H,2H-perfluorooctyltrichlorosilane and alcohol in a mass fraction of 1:100 for 3 minutes. After that, it is removed and dried to obtain the final product.

8. A method for manufacturing a water desalination device according to claim 7, characterized in that, The specific process for preparing the evaporation surface is as follows: Take NaClO2, NaOH, Na3PO4·12H2O and deionized water to prepare a mixed solution with a mass fraction of 3.75:5:10:100, place it in a constant temperature water bath at 95℃, immerse the copper foam in the mixed solution for 10 minutes, take it out and dry it to obtain copper / copper oxide foam; Dissolve 2.74 g of (NH4)2S2O8 in 5 mL of deionized water and label it as monomer A; Mix 0.84 mL of pyrrole with 5 mL of isopropanol and 1.84 mL of phytic acid solution, and label the mixture as monomer B. Then monomers A and B are sprayed alternately onto the copper / copper oxide foam in the order BABA to obtain copper / copper oxide-polypyrrole foam.

9. A method for manufacturing a water desalination device according to claim 7, characterized in that, The thickener solution is obtained by dissolving 1g of sodium carboxymethyl cellulose in 75g of water and stirring at 80°C for 1-2 hours.

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