Solar evaporator, solar desalination apparatus comprising same, and solar desalination method

Abstract

This solar evaporator comprises: a membrane which includes an inlet part immersed in seawater, and through which the seawater spreads from the inlet part so as to move in one direction; and a photothermal part for evaporating the seawater moving from the membrane. This solar desalination apparatus comprises: a water tank, which has an open top and accommodates the seawater; the solar evaporator, which is mounted on the top of the water tank and evaporates the seawater; and a collection part for collecting moisture evaporated from the solar evaporator, and covering the top of the water tank.

Description

Solar evaporator, solar desalination device including the same, and solar desalination method

[0001] The present invention relates to a solar evaporator, a solar desalination device including the same, and a solar desalination method.

[0002] This research is related to the Individual Basic Research (MSIT) project, specifically the study on high-efficiency / high-stable iron oxide mineral decomposition electrodes for voluntary hydrogen production (Project No.: 2020R1A2C201405011, Project No.: 2710062678, Research Period: 2024.03.01 ~ 2025.02.28), conducted at Ulsan National Institute of Science and Technology with funding from the Ministry of Science and ICT (Government) and support from the National Research Foundation of Korea, and the Research Center for Chemical / Bio Convergence Processes Response to Microplastics (Project No.: 2020R1A5A1019631, Project No.: 2710034967, Research Period: 2024.03.01 ~ 2025.02.28), conducted at Ulsan National Institute of Science and Technology with funding from the Ministry of Science and ICT (Government) and support from the National Research Foundation of Korea.

[0003] Freshwater scarcity is currently one of the most serious problems worldwide that needs to be solved as soon as possible. Membrane distillation (MD), reverse osmosis (RO), and flash distillation have been used as technical solutions to the problem of freshwater scarcity. However, in order to supply essential amounts of fresh water to low-income countries and remote areas, it is necessary to supply fresh water at a lower cost.

[0004] Solar-driven interfacial evaporation is the process of evaporating water at the interface between air and water using a photoabsorber that converts sunlight into heat. Because solar-driven interfacial evaporation can minimize infrastructure and energy requirements, it can be a promising technological solution for producing fresh water from seawater and supplying essential amounts of fresh water to low-income countries and remote areas.

[0005] In photothermal interfacial evaporation, solar energy is the only energy used for the evaporation of water. In addition, to improve photothermal conversion efficiency, various effective photothermal materials, including plasmonic nanomaterials, carbon-based materials, polymer materials, and graphitic hydrogels, have been used as photoabsorbers for photothermal interfacial evaporation.

[0006] However, despite the excellent light absorption performance of these photothermal materials, an excessive supply of water to the light absorber can have an adverse effect on the light-thermal conversion efficiency of the light absorber. In other words, an excessive supply of water to the light absorber can cause a large amount of heat conduction loss because the heat generated in the light absorber by light irradiation is used to unnecessarily heat the water that has been excessively supplied to the light absorber.

[0007] Meanwhile, conventional solar evaporators reduce the photothermal effect and seawater evaporation rate by decreasing the contact area with sunlight as salt accumulates on the surface of the light absorber while seawater evaporates through sunlight. This results in a problem that lowers the efficiency of the solar evaporator and the desalination device containing it.

[0008] Embodiments of the present invention were invented against the background described above, and aim to provide a solar evaporator that is simple in structure, inexpensive, possesses excellent evaporation rate and thermal efficiency, and can be used for a long period without a decrease in evaporation rate, a solar desalination device including the same, and a solar desalination method.

[0009] A solar evaporator according to the first aspect of the present invention comprises: an inlet portion immersed in seawater and a membrane configured to allow the seawater to move in one direction by diffusing from the inlet portion; and a photothermal portion for evaporating the seawater moving in the membrane.

[0010] Additionally, the membrane further includes an evaporator extending to a first length and including the photothermal section; the inlet section and the evaporator section may extend in directions offset from each other.

[0011] In addition, the above membrane may be provided as a glass fiber filter.

[0012] In addition, the present invention further includes a support member that supports the membrane; the support member may block the inlet from sunlight and expose the evaporator to sunlight.

[0013] Additionally, the support member may include a support body that seats the evaporator on one surface, and a slot formed so that the inlet part penetrates the support body.

[0014] Additionally, the above-mentioned photothermal element may be positioned at the center in the longitudinal direction of the above-mentioned evaporator and may be extended to a second length shorter than the first length.

[0015] In addition, the membrane is hydrophilic; and the photothermal part may be hydrophilic.

[0016] In addition, the above-mentioned photothermal element may be provided with a perovskite structure.

[0017] In addition, the above-mentioned photothermal element may include one or more of ratanum, strontium, manganese, and oxygen.

[0018] In addition, the above-mentioned photothermal unit is La 0.7 Sr 0.3 It can be provided as MnO3 (LSMO).

[0019] A solar desalination device according to a second aspect of the present invention may be provided, comprising: a tank having an open top and containing seawater; a solar evaporator seated on the top of the tank and evaporating the seawater; and a collection unit that collects moisture evaporated from the solar evaporator and covers the top of the tank; wherein the solar evaporator may include a membrane configured to allow the seawater to diffuse from the inlet and move in one direction, the membrane comprising an inlet portion immersed in the seawater; and a photothermal unit that evaporates the seawater moving in the membrane.

[0020] Additionally, the above-mentioned collection unit may include a receiving body that accommodates the water tank and the solar evaporator inside; and an inclined cover that moves the fresh water evaporated from the solar evaporator in one direction.

[0021] A solar desalination method according to a third aspect of the present invention comprises: a seawater immersion step of immersing an inlet portion of a membrane in seawater; a seawater movement step of moving the seawater in one direction by allowing the seawater to diffuse from the inlet portion; and a seawater evaporation step of evaporating the seawater moving in the membrane.

[0022] In addition, it may further include a freshwater collection step in which steamed freshwater generated as the seawater evaporates flows in one direction to collect it.

[0023] According to embodiments of the present invention, the light absorber is spaced apart from the water surface, thereby reducing conductive heat loss in the light absorber and controlling the supply of water to the light absorber, so that the light energy supplied to the light absorber can be used for the evaporation of water in the light absorber.

[0024] In addition, according to the embodiments of the present invention, the accumulation of salt on the surface of the light absorber is prevented, thereby enabling long-term use without a decrease in the evaporation rate of the light absorber.

[0025] In addition, according to the embodiments of the present invention, the structure is simple and inexpensive, yet possesses excellent evaporation and thermal efficiency, and can be used for a long period without a decrease in evaporation rate, thereby having the effect of supplying an essential amount of fresh water to low-income countries and remote areas.

[0026] FIG. 1 is a perspective view showing a solar desalination device including a solar evaporator according to one embodiment of the present invention.

[0027] Figure 2 is an exploded perspective view showing the solar evaporator of Figure 1.

[0028] Figure 3 is a perspective view showing the membrane portion of Figure 1.

[0029] Figure 4 is a cross-sectional view showing the solar evaporator of Figure 1.

[0030] Figure 5 is a structural diagram showing the chemical structure of the photothermal part of Figure 1.

[0031] FIG. 6 is a flowchart illustrating a solar desalination method according to one embodiment of the present invention.

[0032] FIG. 7 is a flowchart illustrating a method for producing a material used in the photothermal part of the present invention.

[0033] Figure 8 is a graph showing the absorbance of the photothermal part of Figure 1.

[0034] Figure 9 is a graph showing the measured evaporation rate for the photothermal section of Figure 1.

[0035] FIG. 10 is a partial cross-sectional view showing the location where salt is generated in a solar evaporator according to one embodiment of the present invention.

[0036] FIG. 11 is a graph showing the measured evaporation rate of a solar evaporator according to one embodiment of the present invention.

[0037] Figure 12 is a graph measuring the salinity of fresh water produced through the solar desalination device of the present invention.

[0038] Hereinafter, specific embodiments for implementing the technical concept of the present invention will be described in detail with reference to the drawings.

[0039] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0040] Furthermore, when it is mentioned that one component is 'supported,' 'connected,' 'supplied,' or 'contacted' with another component, it should be understood that while the support, connection, supply, or contact may be direct to that other component, there may also be other components present in between.

[0041] The terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0042] Furthermore, it should be noted in advance that expressions such as "upper side," "lower side," and "side" in this specification are described based on the drawings, and may be expressed differently if the orientation of the object changes. For the same reason, some components in the attached drawings may be exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size.

[0043] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but such components are not limited by such terms. These terms are used solely for the purpose of distinguishing one component from another.

[0044] The meaning of "comprising" as used in the specification is to specify certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0045] Hereinafter, specific configurations of a solar evaporator according to one embodiment of the present invention, a solar desalination device including the same, and a solar desalination method will be described with reference to the drawings.

[0046] Referring to FIG. 1, the solar desalination device (1) of the present invention can produce fresh water by using sunlight to evaporate seawater (W) containing salt and collecting the generated water vapor. Such a solar desalination device (1) may include a water tank (10), a solar evaporator (20), and a collection unit (30).

[0047] The water tank (10) can store seawater (W) containing salt. The top of the water tank (10) may be open. A solar evaporator (20) may be placed on the upper side of the water tank (10). The water tank (10) may be housed inside a collection unit (30). The water tank (10) may be provided with a transparent material.

[0048] Referring to FIGS. 2 to 5, the solar evaporator (20) can absorb sunlight to evaporate seawater (W) and generate water vapor. The solar evaporator (20) can be placed on the upper part of the water tank (10). The solar evaporator (20) can be housed inside the collection unit (30). The solar evaporator (20) may include a membrane (100), a photothermal unit (200), and a support unit (300).

[0049] The membrane (100) can draw in seawater (W) in one direction and move it in the other direction. The membrane (100) may be provided as a glass fiber filter (GFA). The membrane (100) may have a shape of approximately 'Γ'. The membrane (100) may be composed of a single unit. A photothermal unit (200) may be installed on the membrane (100). The membrane (100) may be hydrophilic. Such a membrane (100) may include an inlet (110) and an evaporation unit (120).

[0050] The inlet section (110) may be immersed in seawater (W). The inlet section (110) may be bent at a right angle from the evaporator section (120). The inlet section (110) may be immersed in seawater (W) for a predetermined length. The inlet section (110) may be placed in a non-exposed area that is not exposed to sunlight. When the inlet section (110) is mounted in the water tank (10), it may be extended vertically so as to be immersed in seawater (W). The inlet section (110) may be a passage that moves the seawater (W) contained in the water tank (10) to the evaporator section (120).

[0051] A photothermal section (200) may be disposed in the evaporation section (120). The evaporation section (120) may be extended in a direction offset from the inlet section (110) for a predetermined length. The evaporation section (120) may move seawater (W) in a horizontal direction. In the evaporation section (120), seawater (W) may evaporate and crystallized salt (Sa) may be formed on the surface. The evaporation section (120) may be disposed in an exposed area exposed to sunlight.

[0052] The photothermal section (200) can be exposed to sunlight to generate a photothermal effect. The photothermal section (200) can be positioned at the center along the longitudinal direction of the evaporator section (120). The photothermal section (200) can have a length shorter than the length of the evaporator section (120). The photothermal section (200) can heat and evaporate seawater (W) moving in the evaporator section (120). The photothermal section (200) can be hydrophilic. The photothermal section (200) can be LSMO (Lanthanum Strontium Manganite). The photothermal section (200) can have a structure of perovskites. The photothermal section (200) can include one or more of latanium (La), strontium (Sr), manganese (Mn), and oxygen (O). The photothermal section (200) is La 0.7 Sr 0.3 It could be MnO3.

[0053] The support member (300) can support the membrane (100). The support member (300) can block the inlet (110) from sunlight and expose the evaporation part to sunlight. The support member (300) can be provided to be seated on the upper part of the water tank (10). Such a support member (300) may include a support body (310) and a slot (320).

[0054] The support body (310) can support the evaporator (120) on one side. The support body (310) may be a housing with an open bottom. An extension piece extending toward the water tank (10) may be provided on the rim of the support body (310) so as to be fitted into the upper part of the water tank (10).

[0055] The slot (320) may be a through hole through which the inlet (110) can pass. For example, the slot (320) may be a rectangular opening, the long side of the slot may be provided with a length equal to or greater than the width of the inlet (110), and the short side of the slot (320) may be provided with a length equal to or greater than the thickness of the inlet (110). The inlet (110) may pass through from one side of the slot (320) to the other.

[0056] The collection unit (30) may include a receiving body (31) that accommodates a water tank (10) and a solar evaporator (20) inside, and an inclined cover (32) that moves fresh water evaporated from the solar evaporator (20) in one direction.

[0057] Hereinafter, with reference to the drawings, a specific configuration of a solar desalination method according to one embodiment of the present invention will be described.

[0058] Referring to FIG. 6, a solar desalination method (S1) can desalinate seawater by evaporating it. This solar desalination method (S1) may include a seawater storage step (S100), a seawater transfer step (S200), a seawater evaporation step (S300), and a freshwater collection step (S400).

[0059] The seawater immersion step (S100) may be a step of immersing the inlet portion (110) of the membrane (100) in seawater (W). For example, the seawater immersion step (S100) may extend the inlet portion (110) of the membrane (100) vertically toward the seawater (W) contained in the water tank (10), extend the evaporation portion (120) horizontally so as to be offset from the inlet portion (110), and then immerse the inlet portion (110) in seawater (W).

[0060] The seawater movement step (S200) can move the seawater (W) in one direction. The seawater movement step (S200) can allow the seawater (W) to spread out from the inlet (110). For example, the seawater movement step (S200) may be a step in which the seawater (W) spread out from the inlet (110) moves toward the evaporation section (120) of the membrane (100).

[0061] The seawater evaporation step (S300) can evaporate seawater (W) moving in the membrane (100). For example, the seawater evaporation step (S300) may be a step in which seawater (W) moving in the evaporation unit (120) passes through the photothermal unit (200) and is evaporated by the heat generated by the photothermal effect in the photothermal unit (200) which generates heat by the photothermal effect.

[0062] The freshwater collection step (S400) can collect steamed freshwater generated as seawater (W) evaporates by flowing it in one direction. For example, the freshwater collection step (S400) may be a step in which water vapor evaporated from the heat source (200) condenses on the collection unit (30) positioned at the top and collects freshwater while flowing in an inclined direction.

[0063] The operation and effects of a solar evaporator having the configuration described above, a solar desalination device including the same, and a solar desalination method are explained below.

[0064] Referring to FIG. 7, the lanthanum strontium manganite cathode powder used in the photothermal unit (200) can be produced in the following sequence. First, latanum (La) and strontium (Sr) to be placed at site A and manganese (Mn) to be placed at site B are prepared, and oxygen ions to be placed at site C are mixed in an aqueous solution. Then, potassium hydroxide (KOH) is added to induce a precipitation reaction, and the solid and liquid are separated through centrifugation. The lanthanum strontium manganite cathode powder, which is a precipitate with a perovskite structure, can be produced by drying the centrifuged solid precipitate and then heat-treating it at 750°C.

[0065] The photothermal part (200) may be provided in black. Referring to FIG. 8, the absorbance of the photothermal part (200) is approximately 100% from ultraviolet light of 100 nm to 400 nm to near-infrared light of 780 nm to 2500 nm. Thus, it can be confirmed that the photothermal part (200) is a material capable of absorbing a large amount of sunlight.

[0066] Referring to FIG. 9, the photothermal unit (200) can have a high evaporation rate of seawater (W). Here, when the respective evaporation rates for 3.5% seawater, a glass fiber filter, and the photothermal unit (200) are measured for 60 minutes, it can be confirmed that the evaporation rate of LSMO, which is a component of the photothermal unit (200), is the best.

[0067] Referring to FIG. 10, the solar evaporator (20) can evaporate water as seawater (W) moving from the evaporation section (120) passes through the photothermal section (200). The seawater (W) from which water has been evaporated may leave behind salt (Sa). At this time, salt may be generated at the point where it passes through the photothermal section (200). In other words, the seawater (W) moves by diffusing in the evaporation section (120) until water remains, and solid salt (Sa) can be generated at the point where all the water has evaporated. As a result, the problem of salt (Sa) being generated on the surface of the photothermal section (200) and reducing the contact area with sunlight can be solved, and the evaporation efficiency can be increased.

[0068] Referring to FIG. 11, when the evaporation rate is measured for 12 hours through the solar evaporator (20) according to the present invention, it can be confirmed that a stable and excellent evaporation rate is maintained without irregular changes. Therefore, it can be confirmed that the evaporation efficiency of the solar evaporator (20) of the present invention is excellent.

[0069] Referring to FIG. 12, it can be seen that the concentrations of sodium, calcium, potassium, and magnesium ions in the fresh water produced by the solar desalination device (1) according to the present invention are significantly reduced compared to the ion concentration of seawater (W) before desalination. Therefore, the salinity of the fresh water produced by the solar desalination device (1) according to the present invention is much lower than the salinity level of safe drinking water defined by the World Health Organization (WHO) standards. Thus, it can be confirmed that the desalination efficiency of the solar desalination device (1) of the present invention is excellent.

[0070] Although the embodiments of the present invention have been described above as specific embodiments, they are merely examples and the present invention is not limited thereto, but should be interpreted as having the broadest scope in accordance with the technical concept disclosed in this specification. Those skilled in the art may implement patterns of shapes not specified by combining or substituting the disclosed embodiments, and this also does not deviate from the scope of the present invention. Furthermore, those skilled in the art may easily modify or alter the disclosed embodiments based on this specification, and it is evident that such modifications or alterations also fall within the scope of the rights of the present invention.

Claims

1. A membrane comprising an inlet portion immersed in seawater, configured such that the seawater moves in one direction by diffusing from the inlet portion; and A photothermal unit comprising a photothermal unit that evaporates the seawater moving in the above membrane, Solar evaporator.

2. In Paragraph 1 The above membrane is, The above-mentioned photothermal section and further including an evaporator section extending to a first length; The above inlet and the above evaporator extend in directions offset from each other, Solar evaporator.

3. In Paragraph 2 The above membrane is provided as a glass fiber filter, Solar evaporator.

4. In Paragraph 3, It further includes a support member that supports the above membrane; The above support blocks the above inlet from sunlight and exposes the above evaporator to sunlight. Solar evaporator.

5. In Paragraph 4, The above support member is, A support body that supports the evaporator on one surface, and a slot formed such that the inlet penetrates the support body. Solar evaporator.

6. In Paragraph 5, The above-mentioned photothermal unit is, A portion disposed at the center in the longitudinal direction of the above evaporator and extending to a second length shorter than the first length, Solar evaporator.

7. In Paragraph 6, The above membrane is hydrophilic and the above photothermal part is hydrophilic, Solar evaporator.

8. In Paragraph 7, The above photothermal element is provided with a perovskite structure, Solar evaporator.

9. In Paragraph 7, The above-mentioned photothermal unit is, Comprising one or more of latanium (La), strontium (Sr), manganese (Mn), and oxygen (O), Solar evaporator.

10. In Paragraph 9, The above-mentioned photothermal part is La 0.7 Sr 0.3 Provided as MnO3(LSMO), Solar evaporator.

11. A tank with an open top containing seawater; A solar evaporator that is mounted on the upper part of the above water tank and evaporates the seawater; and It includes a collection unit that collects moisture evaporated from the solar evaporator and covers the upper part of the water tank; The above solar evaporator is, A membrane comprising an inlet portion immersed in the seawater, configured such that the seawater diffuses from the inlet portion and moves in one direction; and A photothermal unit comprising a photothermal unit that evaporates the seawater moving in the above membrane, Solar desalination device.

12. In Paragraph 11, The above-mentioned capture unit is, A receiving body that accommodates the above-mentioned water tank and the above-mentioned solar evaporator inside; and Includes an inclined cover that moves fresh water evaporated from the above-mentioned solar evaporator in one direction, Solar desalination device.

13. A seawater immersion step for immersing the inlet of the membrane in seawater; A seawater movement step for moving the seawater in one direction by allowing the seawater to diffuse from the inlet; and A seawater evaporation step comprising evaporating the seawater moving in the above membrane, Solar desalination method.

14. In Paragraph 13, A freshwater collection step further comprising collecting vaporized freshwater generated as the above seawater evaporates by flowing it in one direction, Solar desalination method.

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