3D separated double-layer groove evaporator and preparation method and application thereof

Abstract

The application discloses a 3D separated double-layer groove evaporator and a preparation method and application thereof, and has separated and collaborative functional areas to promote multiple utilization of energy, and different functional areas with different effects are constructed by modifying the height of square grooves and the depth of V-shaped grooves, and the channels and high-reflective cotton attached to the side walls can absorb sunlight from different directions for multiple times by designing reasonable height, in addition, the V-shaped groove bottom provides sufficient area for salt water discharge and salt storage, the design of the 3D separated double-layer groove evaporator makes water supply and salt collection more powerful, and synchronous and efficient recovery of water vapor and salt resources is realized.

Description

Technical Field

[0001] This invention belongs to the field of evaporator technology, specifically relating to a 3D split double-layer grooved evaporator, its preparation method, and its application. Background Technology

[0002] Clean water is an indispensable resource for human survival and development. However, severe water scarcity has become a major global challenge. In recent years, extracting freshwater from seawater through solar steam generation (SSG) has emerged as a feasible desalination solution to meet water demand. In the SSG process, sufficient solar and thermal input and ideal thermal energy utilization play a crucial role in efficient desalination. Diverse heat flows can be synergistically used for mineral and electrical extraction, possessing comprehensive resource regeneration potential. Therefore, rational thermal management is of great significance in integrating various aspects of solar desalination technology.

[0003] Efficient thermal management can accelerate interfacial evaporation. Hybrid evaporators compactly integrate components such as photothermal conversion, water supply systems, and even thermal insulation into a single device, achieving centralized heating. Localized heating and interfacial vaporization can lead to reduced water viscosity and air blockage, hindering smooth water circulation. In contrast, while macroscopically separated evaporators avoid inter-component interference, they sacrifice thermal efficiency; large-scale convection flow and strong thermal resistance result in significant energy waste. Therefore, ensuring the coordinated operation of different functional areas to achieve effective heat flow is crucial. Increased available heat can be achieved by increasing photothermal input and reducing energy waste. By constructing a solar capture structure, incident sunlight reflected and scattered by the first receiving surface can be reabsorbed, thereby improving the adaptability of radiation absorptivity and incident angle. By constructing a closed evaporation surface to capture heat, heat convection losses to the surrounding environment can be reduced. This can be achieved by avoiding liquid backflow and modifying the heat transfer medium to a low thermal conductivity air gap (0.02 W·m). -1 ·K⁻¹ can reduce heat transfer loss to the main brine mass (0.6 W·m⁻¹). -1 ·K-1).

[0004] Extensive heat flow within the evaporator facilitates ion and charge transport. However, as evaporation proceeds, particularly in desalination processes with high salinity or high desalination rates, excessive heat flow can restrict aqueous transport, leading to salt blockage and reduced desalination efficiency. The large number of ions in concentrated brine tends to lower the free energy of water molecules. The saturated vapor pressure of brine decreases with increasing salinity, ultimately reducing the evaporation rate. To overcome this limitation, a rational Marangoni effect and thermocapillary flow can be induced through localized heat and directional thermal gradients to modify water flow and ion exchange. Using low-concentration brine for evaporation and saturated brine for discharge can reduce evaporation energy consumption. Simultaneously, the external expansion of cogeneration induced by heat flow is a comprehensive approach to achieving diversified energy utilization. Low-grade heat, often wasted, can be reused for thermoelectric regeneration through asymmetric energy allocation. In long-term operation, a stable heat flow resilient to environmental disturbances plays a crucial role in ensuring continuous charge migration and power output. A heat flow utilization strategy needs to be developed to mitigate power generation degradation caused by environmental convective heat loss and salt blockage. However, evaporators only possess one or a few of these key factors. Integrating all these factors into a single evaporator remains a significant challenge. In particular, the trade-off between independently constructed functional areas and efficient collaborative operation severely limits the thermal management required to achieve ideal desalination performance.

[0005] Existing technologies address salt crystallization at the light-absorbing interface by spraying hydrophobic materials onto the evaporation interface. However, this method leads to salt crystallization and accumulation within the pores of the evaporator, resulting in insufficient water supply, increased thermal resistance, and ultimately, a reduced evaporation rate. Furthermore, existing technologies utilize capillary forces between the pores of porous media to supply water to the evaporation interface. However, these porous media require complex synthesis processes to ensure pore connectivity and appropriate size, thereby providing sufficient water supply while minimizing heat loss. Moreover, existing technologies rely on expensive materials and complex synthesis processes, making them unsuitable for industrial-scale production.

[0006] Given the shortcomings of the aforementioned seawater desalination equipment, it is necessary to improve it. Summary of the Invention

[0007] This invention provides a 3D separated double-layer grooved evaporator, its preparation method, and its application. It can solve the problem that existing evaporators can maintain stable operation under significant salt accumulation, but their evaporation efficiency is often significantly limited by environmental heat loss and aqueous solution diffusion resistance. In particular, the trade-off between independently constructed functional areas and efficient synergistic operation severely limits the thermal management required to achieve ideal desalination performance.

[0008] To solve the above problems, the technical solution provided by the present invention is as follows:

[0009] This invention provides a 3D split-type double-layer grooved evaporator, including a trough-type foam floating structure (2) located on the surface of seawater (5). The trough-type foam floating structure (2) includes a square groove (2-2) and a V-shaped groove (2-1) located below the square groove (2-2). The surface of the trough-type foam floating structure (2) is covered by a hydrophilic mass transfer layer (1). A hydrophobic light-absorbing layer (3) is provided between the square groove (2-2) and the V-shaped groove (2-1). The internal space of the V-shaped groove (2-1) is a salt collection area (4). Under sunlight, water molecules in the seawater (5) can... Under the hydrophilic directional concentration effect of the hydrophilic mass transfer layer (1), seawater will migrate from the bottom to the top of the trough-type foam floating structure (2), and water vapor will continuously rise. By adjusting the height of the square groove (2-2) and the depth of the V-shaped groove (2-1), a dynamic balance between heat input and water input can be achieved. Light is absorbed by the hydrophobic light-absorbing layer (3) and converted into heat. The solution seawater (5) can be concentrated step by step. The water supply flow rate can be controlled, and the salt concentration rate can be effectively regulated. The saturation concentration is just limited to the bottom of the V-shaped groove (2-1), realizing the synchronous and efficient recovery of water vapor and salt resources, and efficiently guiding salt crystallization to the salt collection area (4) of the evaporator.

[0010] In a preferred embodiment of the present invention, the height of the square groove is 1-5 cm and the depth of the V-shaped groove is 0.5-2 cm.

[0011] In a preferred embodiment of the present invention, the hydrophilic mass transfer layer (1) is prepared as a double-layer cotton fabric using an industrial loom. The hydrophilic cotton yarns of the double-layer cotton fabric are arranged simultaneously in the warp and weft directions. The fabric is divided into upper and lower layers by the loom program control, and the warp and weft yarns are woven into a double-layer structure.

[0012] In a preferred embodiment of the present invention, the hydrophobic light-absorbing layer (3) is formed by polypyrrole and hydrophobic treatment on the upper fabric surface of the hydrophilic cotton fabric.

[0013] In a preferred embodiment of the present invention, the trough-type foam floating structure (2) is made of hydrophobic foam.

[0014] This invention provides a method for preparing a 3D split-type double-layer groove evaporator, characterized by the following steps:

[0015] Step 1: Prepare a trough-type foam floating structure using 3D printing technology. The trough-type foam floating structure has a square groove in the middle and a V-shaped groove below the square groove.

[0016] Step 2: A hydrophilic mass transfer layer is prepared on the surface of the trough-type foam floating structure. The hydrophilic mass transfer layer is prepared by using an industrial loom to make a double-layer cotton fabric. The hydrophilic cotton yarns of the double-layer cotton fabric are arranged in both the warp and weft directions. The loom program controls the fabric to divide it into upper and lower layers, and the warp and weft yarns are woven into a double-layer structure.

[0017] The top layer of cotton fibers in the double-layer structure is modified with polypyrrole and then hydrophobically treated. The cotton fabric is ultrasonically treated in anhydrous ethanol for 30 minutes to remove impurities. The original cotton fibers are pretreated by immersing them in SDBS dispersion for about 30 minutes. Subsequently, the pretreated cotton fibers are immersed in ferric chloride solution for pre-oxidation treatment. Pyrrole is added to the ferric chloride solution to carry out polypyrrole polymerization. Then, the PPy layer of the double-layer cotton is hydrophobically treated on one side. The cotton layer remains in its original state, and its length is customized according to the size of the thermal insulation foam.

[0018] Step 3: A hydrophobic light-absorbing layer is provided between the square groove and the V-shaped groove. The hydrophobic light-absorbing layer is formed by treating the upper fabric surface of the hydrophilic cotton fabric with polypyrrole and hydrophobic treatment, and then combined with the trough-type foam floating structure to obtain the photothermal evaporator.

[0019] In a preferred embodiment of the present invention, the specific preparation method of the trough-type foam floating structure is as follows: polylactic acid is used as the raw material, and the trough-type foam is manufactured by a layered 3D printer with a nozzle diameter of 0.4 mm and a printing speed of 30 mm / s; the nozzle and platform temperatures are 210°C and 60°C, respectively; the base size of the trough-type foam floating structure is 5×3 cm, used to construct the stitched flat evaporator (SPE) and the separate flat evaporator (DPE); as for the double-layer grooved evaporator (DGE), a 3×3 cm opening is made at the center of the trough-type foam floating structure to place the top layer absorber, while the bottom layer cotton is fixed to the foam sidewall; the height of the square groove is set to 1-5 cm, and the depth of the V-shaped groove is set to 0.5-2 cm.

[0020] In a preferred embodiment of the present invention, the thickness ratio of the hydrophilic mass transfer layer to the hydrophobic light-absorbing layer is set to 1:1.

[0021] This invention provides an application of a 3D split double-layer groove evaporator in brine treatment, wherein the salt concentration in the brine to be treated is 0-20 wt%, and is not 0.

[0022] Compared with the prior art, the present invention provides a 3D split double-layer grooved evaporator, its preparation method and application, which has the following beneficial effects: The 3D split double-layer grooved evaporator has separate and synergistic functional zones to promote the multiple utilization of energy. By modifying the height of the square groove and the depth of the V-shaped groove, functional zones with different effects can be constructed. The reasonable height design allows the channels and high reflective cotton attached to the side wall to absorb sunlight from different directions multiple times. In addition, the bottom of the V-shaped groove provides sufficient area for brine discharge and salt storage. The design of the 3D split double-layer grooved evaporator makes the water supply and salt collection capacity stronger, realizing the simultaneous and efficient recovery of water vapor and salt resources. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the cross-sectional structure of a 3D split double-layer grooved evaporator provided in an embodiment of this application.

[0025] Figure 2 This is a cross-sectional schematic diagram of a trough-type foam floating structure provided in an embodiment of this application.

[0026] Figure 3 A schematic diagram of a square groove provided in an embodiment of this application.

[0027] Figure 4 The diagram shows a schematic (sectional view) and a physical schematic of a 3D split double-layer groove evaporator for treating brine, as provided in the embodiments of this application.

[0028] Figure 5 This is a schematic diagram illustrating the process of weaving and evaporation device printing of a fabric, as provided in an embodiment of this application.

[0029] Figure 6 This is a schematic diagram of evaporation rate curves with different trench heights provided in an embodiment of this application.

[0030] Figure 7 Evaporation rate curves for different groove depths at a groove height of 3cm, provided for embodiments of this application;

[0031] Figure 8 This is a schematic diagram of the evaporation rate curves of the 20wt% brine treated in this embodiment and the comparative embodiment, provided for the purposes of this application.

[0032] Figure 9The salt collection amounts provided for embodiments of this application and comparative examples.

[0033] Figure 10 This is a schematic diagram showing the changes in ion concentration before and after desalination in outdoor environments throughout the day, provided as an embodiment of this application.

[0034] Figure labels: 1. Hydrophilic mass transfer layer; 2. Trough-type foam floating structure; 2-1. Square groove; 2-2. V-shaped groove; 3. Hydrophobic light-absorbing layer; 4. Salt collection zone; 5. Seawater. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The terms "upper," "lower," "front," "rear," "left," and "right," etc., used when describing the installation position or direction of the structure or components in this embodiment are based on the orientation shown in the accompanying drawings. They are merely for convenience of description, used to distinguish the relative positions of various components or directions, and do not represent the orientation of the device or functional component in this embodiment during use.

[0036] like Figures 1-4 As shown, this embodiment of the invention provides a 3D separated double-layer groove evaporator, including a trough-type foam floating structure 2. The trough-type foam floating structure 2 is located on the surface of seawater 5. The trough-type foam floating structure 2 includes a square groove 2-2 and a V-shaped groove 2-1 located below the square groove 2-2. The surface of the trough-type foam floating structure 2 is covered with a hydrophilic mass transfer layer 1. A hydrophobic light-absorbing layer 3 is provided between the square groove 2-1 and the V-shaped groove 2-2. The internal space of the V-shaped groove 2-1 is a salt collection area 4.

[0037] The height of the square groove 2-2 is 1-5 cm, specifically 1, 2, 3, 4, and 5 cm. The depth of the V-shaped groove 2-1 is 0.5-2 cm, specifically 0.5, 1, 1.5, 2, and 2.5 cm. A preferred embodiment has a square groove 2-2 height of 3 cm and a V-shaped groove 2-1 depth of 2 cm.

[0038] Driven by sunlight, water molecules in seawater 5 can migrate from the bottom to the top of the trough-type foam floating structure 2 under the directional concentration effect of the hydrophilic mass transfer layer 1 and the capillary action. Water vapor continuously dissipates upward. By adjusting the height of the square groove 2-2 and the depth of the V-shaped groove 2-1, a dynamic balance between heat input and water input can be achieved. Light is absorbed by the hydrophobic light-absorbing layer 3 and converted into heat. The solution seawater 5 can be concentrated step by step. The water supply flow rate can be controlled, the salt concentration rate can be effectively regulated, and the saturation concentration can be precisely limited to the bottom of the V-shaped groove 2-1. This achieves the synchronous and efficient recovery of water vapor and salt resources and efficiently guides salt crystallization to the salt collection area 4 of the evaporator.

[0039] In this embodiment, the hydrophilic mass transfer layer 1 is prepared using an industrial loom to create a double-layer cotton fabric. The hydrophilic cotton yarns of the double-layer cotton fabric are arranged simultaneously in the warp and weft directions, and are divided into upper and lower layers by the loom program control, with the warp and weft yarns woven into a double-layer structure. The hydrophobic light-absorbing layer 3 is formed by treating the upper fabric surface of the hydrophilic cotton fabric with polypyrrole and hydrophobic treatment. The trough-type foam floating structure 2 is a structure made of hydrophobic foam.

[0040] This invention also provides a method for preparing a 3D split double-layer grooved evaporator, comprising the following steps:

[0041] Step 1: Prepare a trough-type foam floating structure using 3D printing technology. The trough-type foam floating structure has a square groove in the middle and a V-shaped groove below the square groove.

[0042] Step 2: A hydrophilic mass transfer layer is prepared on the surface of the trough-type foam floating structure. The hydrophilic mass transfer layer is prepared by using an industrial loom to make a double-layer cotton fabric. The hydrophilic cotton yarns of the double-layer cotton fabric are arranged in both the warp and weft directions. The loom program controls the fabric to divide it into upper and lower layers, and the warp and weft yarns are woven into a double-layer structure.

[0043] The top layer of cotton fibers in the double-layer structure is modified with polypyrrole and then hydrophobically treated. The cotton fabric is ultrasonically treated in anhydrous ethanol for 30 minutes to remove impurities. The original cotton fibers are pretreated by immersing them in SDBS dispersion for about 30 minutes. Subsequently, the pretreated cotton fibers are immersed in ferric chloride solution for pre-oxidation treatment. Pyrrole is added to the ferric chloride solution to carry out polypyrrole polymerization. Then, the PPy layer of the double-layer cotton is hydrophobically treated on one side. The cotton layer remains in its original state, and its length is customized according to the size of the thermal insulation foam.

[0044] Step 3: A hydrophobic light-absorbing layer is provided between the square groove and the V-shaped groove. The hydrophobic light-absorbing layer is formed by treating the upper fabric surface of the hydrophilic cotton fabric with polypyrrole and hydrophobic treatment, and then combined with the trough-type foam floating structure to obtain the photothermal evaporator.

[0045] The specific preparation method of the trough-type foam floating structure is as follows: Polylactic acid is used as the raw material, and the trough-type foam is manufactured by a layered 3D printer with a nozzle diameter of 0.4 mm and a printing speed of 30 mm / s; the nozzle and platform temperatures are 210℃ and 60℃, respectively; the base size of the trough-type foam floating structure is 5×3 cm, used to construct the stitched flat evaporator (SPE) and the split flat evaporator (DPE); as for the double-layer grooved evaporator (DGE), a 3×3 cm opening is made in the center of the trough-type foam floating structure to place the top layer absorber, and the bottom layer cotton is fixed to the foam sidewall; the height of the square groove is set to 1-5 cm, and the depth of the V-shaped groove is set to 0.5-2 cm. The thickness ratio of the hydrophilic mass transfer layer to the hydrophobic light-absorbing layer is set to 1:1.

[0046] When the height of the square groove in the trough-type foam floating structure is set to 1, 2, 3, 4, and 5 cm, the resulting evaporators are named DGE-H1, DGE-H2, DGE-H3, DGE-H4, and DGE-H5, respectively. Subsequently, when the depth of the V-shaped groove in the trough-type foam floating structure is set to 0.5, 1.0, 1.5, 2.0, and 2.5 cm, the resulting evaporators are named DGE-D1, DGE-D2, DGE-D3, DGE-D4, and DGE-D5, respectively.

[0047] This invention also provides an application of a 3D split double-layer groove evaporator in brine treatment, wherein the salt concentration in the brine to be treated is 0-20 wt%, and not 0.

[0048] Comparative Example 1: The difference from the embodiment is that the trough-type foam floating structure base has a size of 5×3 cm and is used to construct a stitched flat evaporator (SPE).

[0049] Comparative Example 2: The difference from the embodiment is that the trough-type foam floating structure base has a size of 5×3 cm and is used to construct a stitched, separate, flat evaporator (DPE).

[0050] Performance testing

[0051] Figure 4 The diagram shows the principle (sectional view) and physical image of the 3D separated double-layer groove evaporator for treating brine according to the present invention. Figure 4The system design and operation mechanism of DGE are demonstrated. It consists of a multi-layered, three-dimensional structure that enables coordinated operation with separated functional zones. A double-layered textile, composed of hydrophobic polypyrrole (PPy / cotton) for photothermal conversion and hydrophilic cotton for water supply, achieves heat transfer through low-conductivity air gaps. The textile is tightly wrapped with insulating foam for thermal positioning. The generated heat is synergistically utilized to accelerate evaporation, drive ion flow, and regenerate thermoelectricity. Therefore, the 3D grooved channels can achieve multiple absorption and heat recovery through the wrapped textile structure. The hydrated cotton is subdivided into a low-salinity evaporation zone for low-enthalpy vaporization and a high-salinity discharge zone for salt collection.

[0052] Figure 5 This invention describes the weaving of the double-layer fabric, the printing process of 3D split double-layer grooved evaporators with different structures, and the fabric after the top layer fabric has been treated with polypyrrole.

[0053] Figure 6 and Figure 7 For the evaporation rate curves of different sizes in this embodiment, DGE employs a covered thermally insulating foam and a three-dimensional evaporation layer, with the trench height designed to achieve multi-level refraction and absorption of sunlight, thereby realizing efficient thermal energy utilization. Although the increase in surface area contributes, thermal regulation is the main mechanism of DGE. The evaporation rate of DGE-Hs does not continuously increase with the increase of height (evaporation area), which is due to insufficient thermal regulation.

[0054] Figure 8 The evaporation rate curves for this embodiment and the comparative example of treating 20 wt% brine are shown. After 24 hours of desalination at high salinity (20 wt%), a large amount of salt accumulated in the evaporator. Due to capillary effect and steam escape, the salt enrichment zones of both SPE and DPE were located below the absorption layer. In contrast, the salt in DGE tended to converge towards the bottom of the tank under gravity, thus maintaining the cleanliness and integrity of the side water supply layer. Therefore, the seawater desalination rate of DGE can reach 2.16 kg·m³. -2 ·h -1 Due to sufficient ion replenishment and clean circulation channels, the seawater desalination rate has remained stable after long-term operation.

[0055] Figure 9 For the salt collection amounts in this embodiment and the comparative example, a large amount of salt accumulated in the evaporator after 24 hours of desalination at high salinity (20 wt%). Reasonable and precise water / ion management in DGE can mitigate the negative impact of salt blockage while achieving considerable mineral extraction. Valuable salt mineral resources are synergistically extracted during seawater desalination. It can be seen that the salt collection performance of DGE (11.8 g) is significantly better than that of SPE (6.2 g) and DPE (7.4 g).

[0056] Figure 10This embodiment illustrates the ion concentration changes before and after desalination during the entire day outdoors. After DGE desalination and purification, common metal ions (Ca) in the condensate are... 2+ Mg 2+ Na + K + The pollutants were effectively removed, with a removal rate exceeding 99%. The salinity of the desalinated water meets the WHO standards. These results demonstrate the feasibility of the 3D split-type double-layer groove evaporator for efficient seawater desalination and wastewater treatment.

[0057] The embodiments described in this invention are merely preferred solutions and do not constitute any limitation on this invention. It should be clearly stated that those skilled in the art can make various improvements and optimizations to the invention without departing from its core principles. Such improvements and optimizations, if not exceeding the substantive scope of this invention, should be included within the protection scope of this invention.

[0058] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention constructs a 3D separation-type double-layer grooved evaporator with an adjustable brine transport path, which can efficiently guide salt crystallization to the V-groove region of the material, achieving a highly efficient and stable concentrated brine treatment effect. The principle is as follows: Under sunlight, water molecules in the brine can be directionally concentrated in the photothermal evaporator (directional concentration is due to the hydrophilic effect of the hydrophilic cotton fabric; under capillary action, water will migrate from the bottom to the top). Water vapor continuously escapes upwards, while the lower layer solution can be concentrated step by step. By adjusting the groove height of the 3D separation-type double-layer grooved evaporator, the water supply flow rate can be controlled, effectively regulating the salt concentration rate and precisely limiting the saturation concentration to the bottom of the V-groove, achieving simultaneous and efficient recovery of water vapor and salt resources. That is, this invention achieves multiple absorption and heat recovery through the wrapped textile structure. The hydrated cotton is subdivided into a low-salinity evaporation zone for low-enthalpy vaporization and a high-salinity discharge zone for salt collection. Multiple functional zones, including photothermal conversion, heat localization, brine evaporation, and saturated discharge, are connected in series to achieve efficient energy interaction, thereby accelerating desalination in high-salinity environments. Often overlooked waste heat can be captured and used to construct temperature gradients, promoting low-grade heat exchange for thermoelectric output. Cogeneration of freshwater, salt, and electricity achieves synergistic enhancement and sustainable development of multiple resources.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A 3D split-type double-layer groove evaporator, characterized in that, The system includes a trough-type foam floating structure (2), which is located on the surface of seawater (5). The trough-type foam floating structure (2) includes a square groove (2-2) and a V-shaped groove (2-1) located below the square groove (2-2). The surface of the trough-type foam floating structure (2) is a hydrophilic mass transfer layer (1). A hydrophobic light-absorbing layer (3) is provided between the square groove (2-2) and the V-shaped groove (2-1). The internal space of the V-shaped groove (2-1) is a salt collection area (4). Under the drive of sunlight, water molecules in the seawater (5) are hydrophilic in the hydrophilic mass transfer layer (1). Under the directional concentration of water, seawater migrates from the bottom to the top of the trough-type foam floating structure (2), and water vapor continuously rises. By adjusting the height of the square groove (2-2) and the depth of the V-shaped groove (2-1), a dynamic balance between heat input and water input is achieved. Light is absorbed by the hydrophobic light-absorbing layer (3) and converted into heat. The solution seawater (5) is concentrated step by step. The water supply flow rate is controlled, the salt concentration rate is effectively regulated, and the saturation concentration is just limited to the bottom of the V-shaped groove (2-1). This achieves the synchronous and efficient recovery of water vapor and salt resources, and efficiently guides salt crystallization to the salt collection area (4) of the evaporator. The hydrophilic mass transfer layer (1) is a double-layer cotton fabric prepared by an industrial loom. The hydrophilic cotton yarns of the double-layer cotton fabric are arranged in both the warp and weft directions. The loom program controls the fabric to divide it into upper and lower layers. The warp and weft yarns are woven into a double-layer structure. The top layer cotton fiber in the double-layer structure is modified with polypyrrole and then hydrophobically treated. The hydrophobic light-absorbing layer (3) is formed by polypyrrole and hydrophobic treatment on the upper fabric surface of the hydrophilic cotton fabric.

2. The 3D split-type double-layer groove evaporator according to claim 1, characterized in that, The height of the square groove is 1-5 cm, and the depth of the V-shaped groove is 0.5-2 cm.

3. A 3D separated double-layer grooved evaporator according to claim 1, characterized in that, The trough-type foam floating structure (2) is a structure made of hydrophobic foam.

4. An application of the 3D split double-layer groove evaporator as described in any one of claims 1-3 in brine treatment, wherein the salt concentration in the brine to be treated is 0-20 wt%, and not 0.

5. A method for preparing a 3D split-type double-layer groove evaporator as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Prepare a trough-type foam floating structure using 3D printing technology. The trough-type foam floating structure has a square groove in the middle and a V-shaped groove below the square groove. Step 2: Prepare a hydrophilic mass transfer layer on the surface of the trough-type foam floating structure. The hydrophilic mass transfer layer is a double-layer cotton fabric prepared by an industrial loom. The hydrophilic cotton yarns of the double-layer cotton fabric are arranged in both the warp and weft directions. The loom program controls the fabric to divide it into upper and lower layers, and the warp and weft yarns are woven into a double-layer structure. The top layer cotton fiber in the double-layer structure is modified with polypyrrole and then hydrophobically treated. The cotton fabric is ultrasonically treated in anhydrous ethanol for 30 minutes to remove impurities. The original cotton fiber is pretreated by soaking in SDBS dispersion for 30 minutes. Subsequently, the pretreated cotton fibers were immersed in a ferric chloride solution for pre-oxidation treatment, and pyrrole was added to the ferric chloride solution to carry out polypyrrole polymerization. Subsequently, the PPy layer of the double-layer cotton is treated with a single-sided hydrophobic coating; the cotton layer remains in its original shape, and its length is customized according to the size of the thermal insulation foam. Step 3: A hydrophobic light-absorbing layer is provided between the square groove and the V-shaped groove. The hydrophobic light-absorbing layer is formed by treating the upper fabric surface of the hydrophilic cotton fabric with polypyrrole and hydrophobic treatment, and then combined with the trough-type foam floating structure to obtain the evaporator.

6. The method for preparing a 3D split double-layer grooved evaporator according to claim 5, characterized in that, The specific preparation method of the trough-type foam floating structure is as follows: polylactic acid is used as the raw material, and the trough-type foam is manufactured by a layered 3D printer with a nozzle diameter of 0.4 mm and a printing speed of 30 mm / s; the nozzle and platform temperatures are 210℃ and 60℃, respectively; the base size of the trough-type foam floating structure is 5×3 cm, which is used to construct the stitched flat evaporator (SPE) and the separate flat evaporator (DPE); as for the double-layer grooved evaporator (DGE), a 3×3 cm opening is made in the center of the trough-type foam floating structure to place the top layer absorber, and the bottom layer cotton is fixed to the foam sidewall; the height of the square groove is set to 1-5 cm, and the depth of the V-shaped groove is set to 0.5-2 cm.

7. The method for preparing a 3D split double-layer grooved evaporator according to claim 5, characterized in that, The thickness ratio of the hydrophilic mass transfer layer to the hydrophobic light-absorbing layer is set to 1:1.

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