Method and system for obtaining dew condensation surfaces using a surface to be treated, and high-performance dew collection system

Abstract

The invention relates to a method and system for obtaining dew condensation surfaces in the form of a film, using a surface to be treated, and to a high-performance dew collection system. Described is a method for producing dew condensation surfaces in the form of a film, based on the micrometric and nanometric modification of the original surface by means of a laser beam, said surface being formed as a flat tile with a plurality of parallel longitudinal grooves. The present invention also describes a passive, robust, durable, high-performance dew collection system.

Description

[0001] DESCRIPTION

[0002] METHOD AND SYSTEM FOR OBTAINING DEW WATER CONDENSATION SURFACES FROM A SURFACE TO BE TREATED AND SYSTEM FOR HIGH-PERFORMANCE DEW WATER COLLECTION.

[0003] OBJECT OF THE INVENTION

[0004] The present invention falls within the field of atmospheric water harvesting. Specifically, it relates to a method for obtaining dew condensation surfaces from a treated surface using a laser beam. Furthermore, passive, robust, long-lasting, and high-performance dew collection systems based on this method are described.

[0005] BACKGROUND OF THE INVENTION

[0006] It is a fact that the world faces a growing water scarcity problem. According to the United Nations Sustainable Development Goals Report for 2023, around 28% of the world's population, or 2.2 billion people, currently lack access to safely managed drinking water. Along with increased water use efficiency and reduced water pollution levels, exploring alternative sources of clean water is one of the necessary actions to address this global challenge.

[0007] Capturing atmospheric water in the form of dew or fog is one of the strategies currently being studied for collecting clean, residue-free water. Nature serves as inspiration for the development of materials and systems for collecting water from the atmosphere. Examples include how different systems of animal or plant origin serve this purpose: spider silk structures, cactus spines, and the skin of various beetle and frog species.

[0008] Dew and fog are two distinct sources of atmospheric water that require different physical mechanisms for collection. In dew, water vapor condenses upon contact with a cold surface. This process requires the extraction of the water's latent heat of condensation. In contrast, fog water is already in a liquid state as tiny droplets suspended in the air. Therefore, fog collection is technically simpler and generally yields a higher amount of water: dew water yields are typically less than 0.3 mm (1 mm equates to 1 L per m³). 2 ) per night, while tens of millimeters per night can be obtained using fog collectors. However, the environmental conditions required for fog collection are more demanding, restricting it to coastal areas, whereas dew is available virtually everywhere on the planet.

[0009] The most direct implication of dew dependence on the condensation phase change is the consequently important role played by surface wettability in the process. For condensation to occur, water molecules must overcome an energy barrier that arises from the newly formed interfaces when a liquid nucleus appears. Unlike nucleation within the bulk gas phase (i.e., homogeneous nucleation), liquid nucleation is facilitated on a surface (i.e., heterogeneous nucleation). Here, the greater the surface wettability, the lower the nucleation energy barrier, which disappears when the contact angle with the surface water reaches zero.

[0010] In addition to the nucleation rate, surface wettability also defines how water is distributed across the condensation surface. Individual droplet patterns (i.e., droplet condensation) generally form on hydrophobic surfaces. Conversely, water tends to spread and form a continuous film (i.e., film condensation) on hydrophilic surfaces.

[0011] In this regard, despite the higher nucleation rate on hydrophilic surfaces, the film-like condensation regime they exhibit is often considered detrimental to the water harvesting process. For these reasons, surfaces combining hydrophobic and hydrophilic areas have been studied to combine the advantages offered by both.

[0012] The manufacture of these types of composite surfaces is a complex and generally expensive process. Furthermore, the resulting surfaces are not robust in terms of their long-term durability and are susceptible to weathering, since the dew collection systems must be located outdoors.

[0013] Another type of atmospheric water harvesting system uses absorbent materials. Generally made from hygroscopic salts, polymer gels, or metal-organic frameworks, these materials absorb water molecules from the environment and release them as droplets. These materials have been used in laboratory settings, but their viability as materials for constructing water harvesting systems suitable for use under normal environmental conditions has not yet been conclusively proven. Furthermore, they are not very robust and have limited durability.

[0014] That is why it is necessary to develop a new robust, efficient and long-lasting dew water collection system.

[0015] To this end, the present invention presents a method for treating a surface to obtain homogeneously superhydrophilic, high-emissivity water condensation surfaces by means of a laser beam. It also describes a passive, autonomous, robust, long-lasting, and high-performance dew collection system.

[0016] SUMMARY OF THE INVENTION

[0017] The present invention provides a method for obtaining homogeneously superhydrophilic, high-emissivity water condensation surfaces according to claim 1 and a system for obtaining film-like water condensation surfaces according to claim 15. A passive, self-contained, robust, long-lasting, high-performance water collection system is also described according to claim 17. Preferred embodiments of the invention are defined in the dependent claims.

[0018] The first inventive aspect presents a method for obtaining dew condensation surfaces in the form of a film from a surface to be treated, characterized in that it comprises: providing a material with a substantially flat surface to be treated, cutting the contour of the surface to be treated in the form of a flat tile, with a rectangular perimeter, having two longer sides and two shorter sides and with a pointed end on one of its shorter sides, modifying the topography of said surface to be treated at the micrometric and nanometric level, forming a plurality of longitudinal grooves parallel to each other and substantially parallel to the long sides, applying to the surface to be treated a laser beam whose wavelength is within the range of 100 nm to 11000 nm.Advantageously, applying the laser beam within that wavelength range maximizes the emissivity of these surfaces, minimizes the nucleation energy of the water droplets, achieves a homogeneously superhydrophilic behavior, produces condensation of the water in the form of a film, and achieves continuous and efficient evacuation of the condensed water.

[0019] Specifically, the tile-shaped surface configuration with a plurality of longitudinal grooves parallel to each other and substantially parallel to the long sides, along with a pointed end, facilitates the collection of condensed water by directing and concentrating it in these pointed areas.

[0020] In the context of the invention, the term longitudinal groove refers to a groove or channel that extends along the surface to be treated in a specific direction.

[0021] In the context of the invention, the surface to be treated is a surface of a material, composite or part on which the method of this invention is to be applied.

[0022] In the context of the present invention, exposure of the laser beam on the surface to be treated shall be understood as the natural logarithm of the quotient of the laser power squared, divided by the square root of the processing speed.

[0023] In one embodiment, the laser beam performs a continuous sweep across the surface to be treated, following a specific geometric pattern, or irradiates the entire surface in a single exposure. An example of irradiating the entire surface is the DLIP (Direct Laser Interference Patterning) technique. Advantageously, this technique allows for increased surface treatment speed.

[0024] In one embodiment, the laser beam is scanned using a Cartesian kinematic system or a head consisting of one or more mirrors. Advantageously, these systems are simpler and less expensive than those using the DLIP technique.

[0025] Preferably, the longitudinal grooves, parallel to each other and substantially parallel to the long sides, are substantially perpendicular to a horizontal plane of the surface to be treated. Advantageously, the surface modification in the form of longitudinal grooves parallel to each other and substantially perpendicular to the horizontal plane maximizes the emissivity of these surfaces, minimizes the nucleation energy of the water droplets, produces condensation of the water in the form of a film, and achieves continuous and efficient drainage of the condensed water.

[0026] In one particular embodiment, the modification of the material's surface topography comprises the formation of a lattice structure on the surface. Advantageously, this lattice structure allows for the collection of condensation water in two directions.

[0027] In one embodiment, the exposure of the laser beam on the surface of the material to be treated is in the range between 0.1 W 2 m -05 s 05 and 100 W 2 m -05 s 05 , and more preferably in the range between 1 W 2 m' 05 s 05 and 10 W 2 m -05 s 05 .

[0028] Advantageously, an exposure of the laser beam within this range allows for optimal modification of the surface topography, maximum emissivity, homogeneously superhydrophilic behavior, and optimal condensation of water in film condensation regime.

[0029] In one embodiment of the method of the present invention, the material or part to be treated is a metal, a ceramic, a polymer, a natural rock, a hybrid material (also known as a “composite”), etc. In one particular embodiment, the material or part to be treated is an alloy of aluminum, lithium, magnesium, titanium, manganese, niobium, thallium, vanadium, zinc, chromium, cadmium, indium, gallium, iron, cobalt, copper, nickel, silver, tin, or a combination of all or some of these alloys.

[0030] In one particular embodiment, the irradiation of the laser beam onto the surface to be treated is carried out in a vacuum.

[0031] In a particular embodiment, the irradiation of the laser beam on the surface to be treated is carried out in the presence of an oxidizing or reactive atmosphere.

[0032] In one embodiment, the oxidizing gas is O2, CO2, or mixtures thereof. Advantageously, this oxidizing gas atmosphere promotes the formation of oxides during the action of the laser beam on the material, thereby maximizing the emissivity of the treated surfaces, minimizing the nucleation energy of the water droplets, and producing condensation of the water in the form of a film.

[0033] In one embodiment, the laser source used to generate the laser beam radiation is selected from Nd:YAG, Nd:glass, Nd:YVÜ4, Er:YAG, Yb:YAG, Tm:YAG, diode, fiber, disk, CO2, CO, HeCd, copper vapor, mud, Argon, Krypton or chemical lasers (HF, DF).

[0034] Advantageously, the use of this type of laser source allows maximizing the emissivity of the treated surfaces, minimizing the nucleation energy of the water droplets, and producing the condensation of water in the form of a film on a large number of materials with different chemical compositions.

[0035] In one embodiment, the laser source used emits radiation in pulsed or continuous mode. In a more particular embodiment, the laser used emits in pulsed mode with pulse durations between milliseconds and femtoseconds, and more favorably in the range of 1 to 500 nanoseconds.

[0036] Advantageously, the use of this laser pulse duration range allows maximizing the emissivity of the treated surfaces, minimizing the nucleation energy of the water droplets, achieving a homogeneously superhydrophilic behavior, and producing the condensation of water in the form of a film on a large number of materials with different chemical compositions.

[0037] In one embodiment of the method, the material or part to be treated has a non-flat shape and the laser performs a scan over the surface of the material or part to be treated by means of a three-dimensional optical scanning system.

[0038] In one embodiment of the method, the laser beam performs a scan over the surface of the material or part to be treated by means of a two-dimensional optical scanning system.

[0039] Optionally, the method of the present invention is carried out with the surface of the material to be treated submerged in a liquid, preferably water, hydrogen peroxide, an acid diluted in water, an organic liquid, or mixtures thereof.

[0040] Advantageously, this liquid can interact with the laser beam and promote the formation of oxides during the action of the laser beam on the material, in such a way as to maximize the emissivity of the treated surfaces, minimize the nucleation energy of the water droplets and produce the condensation of the water in the form of a film.

[0041] Additionally, the method for obtaining water condensation surfaces from a surface to be treated according to any of the preceding embodiments comprises applying a second treatment to the already treated surface, intended to stabilize and / or passivate the surface. In particular embodiments, this second treatment is a heat treatment, the application of a coating or paint, the spraying of a nanoparticle layer, immersion in a passivating liquid, or a combination of several of these treatments.

[0042] Optionally, the method of the present invention can be applied to the inner faces of a hollow body such as an inverted truncated hollow pyramid or an inverted hollow frustum of a cone. This hollow geometry also allows for minimizing the negative effect of wind on the condensation of dew water.

[0043] The method that is the subject of the present invention is universally applicable to a wide variety of materials, so that the condensation of dew water is achieved by forming homogeneously superhydrophilic, high-emissivity surfaces, simultaneously benefiting from their radiative cooling capabilities and their high water nucleation rate.

[0044] In a second inventive aspect, a system is presented for obtaining water condensation surfaces from a surface to be treated comprising

[0045] - Fastening means configured to support the material whose surface is to be treated,

[0046] - A laser beam device configured to irradiate a laser beam onto the surface to be treated according to any of the embodiments of the first inventive aspect.

[0047] In one embodiment, the system further comprises cutting means for shaping the contour of the surface to be treated into a flat tile with a rectangular perimeter, two longer sides, two shorter sides, and a pointed end on one of its shorter sides. Advantageously, the cutting means allow the contour of the surface to be treated to be shaped into a flat tile when the surface to be treated does not have this geometric configuration. In a third inventive aspect, a water collection system is presented comprising at least one material with at least one surface treated according to any embodiment of the method of the first inventive aspect.

[0048] In one embodiment, the water collection system comprises a plurality of treated surfaces arranged in a contiguous row. Advantageously, this arrangement allows for increased water collection, essentially multiplying the collection from one treated surface by the number of surfaces in the plurality of treated surfaces.

[0049] In another embodiment, the water collection system comprises at least two rows, each row comprising a plurality of treated surfaces arranged contiguously, with the plurality of treated surfaces in one row partially overlapping the plurality of treated surfaces in the other row. Advantageously, this arrangement, similar to a conventional roof, also allows for a substantial increase in the amount of water collected.

[0050] Any of the systems described in this third inventive aspect is passive, meaning it does not require an external power source and can operate autonomously. Furthermore, they do not require the use of water-absorbing materials and are long-lasting, high-performance systems for collecting dew.

[0051] DESCRIPTION OF THE DRAWINGS

[0052] To complement the description being made and in order to help a better understanding of the characteristics of the invention, the following figures are included as an integral part of said description.

[0053] Figure 1 This figure shows the topographic profile of the surface of an aluminum alloy sheet prior to the application of the method of the present invention. The image was obtained by means of optical profilometry.

[0054] Figure 2 shows the topographic profile of the surface of an aluminum alloy sheet after applying the method of the present invention. The image was obtained by optical profilometry. Figure 3 shows the emissivity in the [8 - 13] micrometer range for an aluminum alloy before and after applying the method of the present invention. Note the enormous increase in emissivity provided by applying the method of the present invention. The emissivity increases from a value of 0.03 ± 0.02 to a value of 0.92 ± 0.02, representing a 3000% increase thanks to the application of the method of the present invention.

[0055] Figure 4 shows the results of a radiation cooling test performed on an aluminum alloy before and after applying the method of the present invention. It can be seen that the material subjected to the method of the present invention is cooled 5°C below ambient temperature. The material before the treatment was cooled by only 2°C. Since all ambient conditions (temperature, humidity, airflow, etc.) were the same during the test of both materials, it is demonstrated that the reason for the greater radiation cooling is due to the higher emissivity of the material after being subjected to the method of the present invention.

[0056] Figure 5. This figure shows the surface appearance of an aluminum alloy sheet prior to the application of the method of the present invention, after being subjected to a water vapor condensation test (test conditions: material temperature of 14.7 °C, ambient temperature of 30 °C, and 70% relative humidity). Note the formation of droplets, a clear indication of a drop-by-drop condensation regime.

[0057] Figure 6 This figure shows the surface appearance of an aluminum alloy sheet after the application of the method of the present invention, following a water vapor condensation test (test conditions: material temperature of 14.7 °C, ambient temperature of 30 °C and 70% relative humidity). Note that, in this case, the condensation regime is by film.

[0058] Figure 7. This figure illustrates the process of collecting condensed water on the surface of a material where condensation occurs drop by drop. The drops grow until they slide down the surface. This is a discontinuous process. Figure 8. This figure illustrates the process of collecting condensed water on the surface of a material where condensation occurs by film. A continuous flow of water is produced on the surface to which the method of the present invention has been applied, such that it accumulates at the bottom until its weight overcomes the surface tension and it detaches from the material. This is a continuous process.

[0059] Figure 9. This figure shows examples of designs for a basic condensation water collection system. The water collects at the bottom of the square shape and is continuously collected in a suitable container to prevent evaporation (not shown in the figure). Each line in the figures indicates the formation of a groove, as shown in Figure 2.

[0060] Figure 10. This figure shows an example of a tile-shaped condensation water collection system. The water collects on the underside of the tile and is continuously collected in a suitable container to prevent evaporation (not shown in the figure). Each line in the figures indicates the formation of a groove, as shown in Figure 2.

[0061] Figure 11. This figure shows an example of a condensation water collection system with a broken finish and several pointed areas for water collection. The water concentrates on the pointed parts and is continuously collected in a suitable container to prevent evaporation of the collected water (not shown in the figure). Each line in the figures indicates the formation of a groove like those shown in Figure 2.

[0062] Figure 12. This figure shows an example of a condensation water collection system with an inverted domed finish and several pointed areas for water collection. The water concentrates on the pointed areas and is continuously collected in a suitable container to prevent evaporation (not shown in the figure). Each line in the figures indicates the formation of a groove like those shown in Figure 2. Figure 13. This figure shows an example of a condensation water collection system with a domed finish and several pointed areas for water collection. The water concentrates on the pointed areas and is continuously collected in a suitable container to prevent evaporation (not shown in the figure). Each line in the figures indicates the formation of a groove like those shown in Figure 2.

[0063] Figure 14 This figure illustrates the operation of an example of a condensation water collection system formed by the superposition of different individual tile-shaped systems (as shown in Figure 10) overlapping one another. The water concentrates on the pointed parts of the tiles and is continuously collected in a suitable container to prevent evaporation of the collected water.

[0064] Figure 15. This figure shows an example of a condensation water collection system formed by the superposition of different individual tile-shaped systems (as shown in Figure 10) overlapping one another. The water concentrates on the pointed parts of the tiles and is continuously collected in a suitable container to prevent evaporation of the collected water.

[0065] DETAILED EXPLANATION OF THE INVENTION

[0066] The present invention, according to the first inventive aspect, is a method for obtaining water condensation surfaces in the form of a film from a surface to be treated.

[0067] The method for obtaining water condensation surfaces in the form of a film, which is the subject of the present invention, comprises providing a material with a substantially flat surface to be treated, cutting the contour of the surface to be treated in the shape of a flat tile, with a pointed end on one of its shorter sides, and modifying the topography of said surface to be treated at the micrometric and nanometric level, forming a plurality of longitudinal grooves parallel to each other and substantially parallel to the long sides, by applying a laser beam to the surface to be treated, the wavelength of which is within the range of 100 nm to 11000 nm. The tile-shaped cut of the contour of the surface to be treated gives the surface a rectangular geometry, with two longer sides and two shorter sides.

[0068] Applying the laser beam within that wavelength range maximizes the emissivity of these surfaces, minimizes the nucleation energy of the water droplets, achieves a homogeneously superhydrophilic behavior, produces condensation of water in the form of a film, and achieves continuous and efficient evacuation of the condensed water.

[0069] Specifically, the tile-shaped surface configuration with a plurality of longitudinal grooves parallel to each other and substantially parallel to the long sides, along with a pointed end, facilitates the collection of condensed water by directing and concentrating it in these pointed areas.

[0070] The laser beam can perform a continuous sweep across the surface following a specific geometric pattern, or it can be expanded to irradiate the entire surface to be treated in a single exposure, as is the case with the DLIP (Direct Laser Interference Patterning) technique. The laser beam sweep can be performed using a Cartesian kinematic system or by employing a head consisting of one or more mirrors.

[0071] The application stage of a laser beam to the surface to be treated may include a substage in which at least one of the following parameters is adjusted: average laser beam power, laser beam size at focus, pulse width, wavelength, type of interaction (fusion / vaporization), and distance between consecutive laser beam sweeps across the surface, in such a way as to obtain the desired exposure. These parameters are easily controllable and tunable depending on the type of material being treated, and their effects are visible in the modification of the surface topography, emissivity, and condensation capacity.

[0072] The exposure of the laser beam on the surface of the material to be treated is in the range between 0.1 W 2 m -05 s 05 and 100 W 2 m -05 s 05 , and more preferably in the range between 1 W 2 m -05 s 05 and 10 W 2 m-05 s 05 Advantageously, laser beam exposure within this range allows for optimal modification of the surface topography, maximum emissivity, homogeneous superhydrophilic behavior, and optimal water condensation under film condensation conditions. The action of the laser beam on the surface to be treated produces a change in its topography, as shown in Figure 2 (treated material) compared to that shown in Figure 1 (untreated material). Figure 2 also shows the topographic profile of the surface of an aluminum alloy sheet after application of the method of the present invention. The image was obtained by optical profilometry.

[0073] The application of the method of the present invention produces a drastic change in the emissivity of the material to which it is applied, as shown in Figure 3. The application of the method of the invention to a material produces an increase of 3000%. This drastic increase in emissivity allows the material treated with the method of the invention to cool by radiation to a lower temperature than the untreated material, as shown in Figure 4.

[0074] At the same time, the method that is the subject of the invention minimizes the nucleation energy of the water droplets on the treated surface, causing a homogeneously superhydrophilic behavior, so that the condensation of the water occurs in the form of a film (see figure 6) and not drop by drop (figure 5) as happens on an untreated surface.

[0075] Surfaces treated with the method of the invention can be used to collect condensation (dew) more efficiently than untreated surfaces. On untreated surfaces (Figure 7), condensation occurs drop by drop. The droplets grow until they slide down the surface. This is a discontinuous process.

[0076] Conversely, on the treated surfaces (Figure 8), condensation occurs in a film-like manner. A continuous flow of water is produced on the surface to which the method of the present invention has been applied, such that the water accumulates at the bottom until its weight overcomes the surface tension and it detaches from the material. This is a continuous process.

[0077] The method of the present invention can be used to manufacture condensation (dew) collection systems in film form in a simple manner. Simple systems such as those shown in Figure 9 can thus be obtained.

[0078] Figure 10 shows a surface treated with the method of the invention with a surface treated with a flat tile-shaped contour, i.e., with a rectangular perimeter, with two longer sides and two shorter sides, with a pointed end on one of its shorter sides, and with a plurality of longitudinal grooves parallel to each other and substantially parallel to the long sides.

[0079] Figures 11 to 13 show embodiments with different configurations of pointed ends of a surface treated with the method of the invention.

[0080] Figure 14 shows an arrangement comprising two rows, each row comprising a plurality of surfaces treated according to the method of the invention, arranged contiguously, with the plurality of treated surfaces in one row partially overlapping the plurality of treated surfaces in the other row. Specifically, the upper row of tile-shaped treated surfaces with a pointed end slightly overlaps the lower row of tile-shaped treated surfaces with a pointed end.

[0081] These systems are passive (they do not need an external energy input), autonomous, robust, long-lasting, and have a high performance in terms of collecting dew water per night.

[0082] The method of the present invention can also be applied directly to flat or curved surfaces, which are then joined to form a three-dimensional shape such as an inverted truncated hollow pyramid. The interior walls of the hollow pyramid are treated by the method of the invention so that water condenses on these walls and is collected at the bottom. Under a film condensation regime, the water condenses and flows to the bottom of the inverted truncated hollow pyramid, where it is collected by a container that prevents evaporation after sunrise. The hollow pyramid geometry minimizes the negative effect of wind on the condensation of dew on the system's walls.

[0083] The method of the invention can also be applied to a flat sheet, which, after treatment, is shaped into an inverted hollow truncated cone. Dew condenses on the inner wall of the hollow truncated cone. Under film condensation, the water condenses and flows to the bottom of the inverted truncated cone, where it is collected by a container that prevents evaporation after sunrise. The hollow truncated cone geometry minimizes the negative effect of wind on dew condensation on the system walls.

[0084] EXAMPLES

[0085] Example 1:

[0086] The method of the invention was applied to the surface of AISI 304 stainless steel. For this purpose, a 7 W average power Nd:YVÜ4 (532 nm) laser was used, operating at a frequency of 20,000 Hz, a line spacing of 100 micrometers, a pulse duration of 14 ns, an energy per pulse of 0.3 mJ, with a scan speed of 25 mm / s and in an air atmosphere. An exposure of 2.3 W was applied. 2 m -05 s 05 A surface is generated that exhibits high emissivity compared to the untreated material and with minimal condensation energy of the dew water, allowing a condensation regime by film formation.

[0087] Example 2:

[0088] The method of the invention was applied to the surface of aluminum alloy 2024. For this purpose, a 13 W average power Nd:YVC>4 (1064 nm) laser was used, operating at 20,000 Hz, with a line spacing of 100 micrometers, a pulse duration of 20 ns, a scan speed of 20 mm / s, and in an air atmosphere. An exposure of 3.6 W was applied. 2 m -05 s 05 A surface is generated that exhibits high emissivity compared to the untreated material and with minimal condensation energy of the dew water, allowing a condensation regime by film formation.

[0089] Example 3:

[0090] The method of the invention was applied to the surface of 6061 aluminum alloy. A 120 W medium-power fiber laser (1064 nm) was used, operating at 20,000 Hz, with a line spacing of 240 micrometers, a pulse duration of 110 ns, a scan speed of 100 mm / s, and in an air atmosphere. An exposure of 7.3 W was applied. 2 m -05 s 05 A surface is generated that exhibits high emissivity compared to the untreated material and with minimal condensation energy of the dew water, allowing a condensation regime by film formation.

[0091] Example 4:

[0092] Applying the method of the invention according to claim 1 and under the conditions detailed in example 3, a dew collection system was constructed as shown in Figure 14. For this purpose, the method of the invention according to claim 1 was applied to 6061 aluminum alloy tiles shaped like roof tiles. Ten tiles were treated and mounted in parallel in two rows of five tiles each, as shown in Figure 15. These tiles were mounted on a thermally insulating support, and this support was mounted on a metal frame inclined at 30 degrees to the horizontal. This system improved dew collection by 70% compared to other similar systems based on the use of high-emissivity paints. Its durability, robustness, and high performance were verified over more than a year of exposure to the elements.

Claims

CLAIMS 1. Method for obtaining dew water condensation surfaces in the form of a film from a surface to be treated, characterized in that it comprises: providing a material with a substantially flat surface to be treated, cutting the contour of the surface to be treated in the form of a flat tile, with a rectangular perimeter, having two longer sides and two shorter sides and with a pointed end on one of its shorter sides, modifying the topography of said surface to be treated at the micrometric and nanometric level, forming a plurality of longitudinal grooves parallel to each other and substantially parallel to the long sides, applying to the surface to be treated a laser beam whose wavelength is within the range of 100 nm to 11000 nm.

2. Method according to claim 1 in which the laser beam performs a continuous sweep over the surface to be treated or irradiates the entire surface to be treated in a single exposure.

3. Method according to any of the preceding claims in which the laser beam sweep is performed by means of a Cartesian kinematic system or by means of the use of a head formed by one or more mirrors.

4. Method according to any of the preceding claims wherein the longitudinal grooves, parallel to each other and substantially parallel to the long sides, are substantially perpendicular to a horizontal plane of the surface to be treated.

5. Method according to the preceding claims wherein the exposure of the laser beam on the surface of the material to be treated is in the range between 0.1 W 2 m -05 s 05 and 100 W 2 m -05 s 05, and more preferably in the range between 1 W 2 m -05 s 05 and 10 W 2 m -05 s 05 .

6. Method according to the preceding claims in which the irradiation of the laser beam on the surface to be treated is carried out in the presence of an oxidizing or reactive atmosphere.

7. Method according to any of the preceding claims wherein the laser source The material used to generate the laser beam radiation is selected from Nd:YAG, Nd:glass, Nd:YVO4, Er:YAG, Yb:YAG, Tm:YAG, diode, fiber, disk, CO2, CO, HeCd, copper vapor, mud, Argon, Krypton or chemical lasers (HF, DF).

8. Method according to any of the preceding claims wherein the laser source used emits radiation in pulsed or continuous mode.

9. Method according to claim 8 wherein the laser source used emits in pulsed mode with a pulse duration between milliseconds and femtoseconds and more favorably in the range of 1 to 500 nanoseconds.

10. Method according to any of the preceding claims wherein the laser beam performs a sweep over the surface to be treated by means of a three-dimensional optical scanning system.

11. Method according to any of claims 1 to 9 wherein the laser beam performs a sweep over the surface to be treated by means of a two-dimensional optical scanning system.

12. Method according to any of the preceding claims wherein the method is carried out with the surface of the material to be treated immersed in a liquid, preferably water, hydrogen peroxide, an acid diluted in water, an organic liquid, or mixtures thereof.

13. Method according to any of the preceding claims comprising applying to the already treated surface a second treatment intended to stabilize and / or passivate the surface.

14. Method according to claim 13 wherein the second treatment comprises a heat treatment, the application of a coating or paint, the spraying of a nanoparticle layer, immersion in a passivating liquid, or a combination of several of these treatments.

15. System for obtaining water condensation surfaces in the form of a film from a surface to be treated comprising, - Fastening means configured to support the material whose surface is to be treated, - A laser beam device configured to irradiate a laser beam onto the surface to be treated according to any of claims 1 to 14.

16. System according to claim 15 comprising cutting means for cutting the contour of the surface to be treated in the form of a flat tile, with a rectangular perimeter, having two longer sides and two shorter sides and with a pointed end on one of its shorter sides 17. Water collection system comprising at least one material with at least one surface treated according to the method of any of claims 1 to 14.

18. Water collection system according to claim 17 comprising a plurality of treated surfaces arranged in a contiguous row.

19. Water collection system according to claim 18 comprising at least two rows, each of which comprises a plurality of treated surfaces arranged contiguously, and the plurality of treated surfaces of one row partially overlapping the plurality of treated surfaces of the other row.

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