Multi-effect solar water treatment device and application

Abstract

This invention relates to a multi-effect solar water treatment device, comprising at least a first chamber and a second chamber, separated by a condensation membrane. A first evaporation layer is disposed on the bottom wall of the first chamber. The first evaporation layer is a light-absorbing material or a light-absorbing material connected to the first evaporation layer. The light-absorbing material absorbs light and converts it into heat to heat the water on the first evaporation layer. A second evaporation layer is disposed on the side of the condensation membrane facing the second chamber. When light shines on the light-absorbing material in the first chamber, the water on the first evaporation layer is heated by the light-absorbing material and forms water vapor. The water vapor releases heat on the condensation membrane to form condensate. The released heat is transferred to the second evaporation layer, heating the water on the second evaporation layer to form water vapor. The formed water vapor condenses on the top wall of the second chamber to form condensate. This device increases the utilization rate of the latent heat of phase change of water vapor without affecting the utilization of light.

Description

Technical Field

[0001] This invention relates to a water treatment device, and more particularly to a multi-effect solar water treatment device and its application. Background Technology

[0002] Solar-powered interfacial evaporation utilizes a specific structure to confine energy to a light-absorbing layer, allowing water to evaporate on the surface of the structure. This avoids heat loss to the water body and offers advantages such as high photothermal conversion efficiency and rapid evaporation. Placing the solar interfacial evaporator within a transparent, sealed chamber (such as a roof-shaped, pyramidal, or conical shape) allows the humidity inside the chamber to gradually rise to saturation as evaporation progresses. The dew point temperature of the water vapor, being higher than the inner wall temperature of the transparent condensation surface, causes condensation, resulting in pure distilled water suitable for applications such as seawater desalination and wastewater treatment. However, the intensity of solar radiation is finite and exhibits uneven distribution over time and space. Recovering and utilizing the latent heat of phase change released during water vapor condensation for multi-effect distillation is the only method to significantly increase the water production per unit area. Specific technical solutions include: 1) Since the latent heat of phase change of water vapor passes through the light-transmitting condensing surface and dissipates to the surrounding environment through the outer surface, water can be used to wash the outer surface of the light-transmitting condensing surface to absorb this heat and achieve the effect of cooling the light-transmitting condensing surface and accelerating condensation; 2) Water vapor is transferred to an independently set multi-effect condensing device using temperature difference, exhaust fan, etc. The device is equipped with multiple stacked seawater pans. Water vapor condenses and releases latent heat on the bottom surface (tilted) of the seawater pan, heating the seawater in the pan and evaporating. The water vapor diffuses upward and condenses again, becoming the evaporation heat source of the upper seawater pan, thus utilizing the latent heat of phase change of water vapor multiple times to increase water production.

[0003] Washing the translucent condenser surface with water can only recover a portion of the heat energy, and the resulting hot water is used to preheat the seawater in the solar distiller, resulting in low utilization efficiency. An external multi-effect condenser can perform multi-effect evaporation, but water vapor will experience heat loss during transmission, reducing the overall utilization efficiency. Summary of the Invention

[0004] In order to efficiently utilize the latent heat of phase change of water vapor, this invention provides a multi-effect solar water treatment device. By rationally setting the positional relationship, structure, and material layers of each chamber, the device can improve the utilization rate of the latent heat of phase change of water vapor without affecting the utilization of light.

[0005] The technical solution adopted in this invention is as follows: a multi-effect solar water treatment device, comprising a first chamber and a second chamber, separated by a condensation membrane. The first chamber includes a bottom wall, and a first evaporation layer is disposed on the bottom wall of the first chamber. The first evaporation layer is a light-absorbing material or has a light-absorbing material disposed on it. The light-absorbing material absorbs sunlight and converts it into heat to heat the water on the first evaporation layer. The condensation membrane is a transparent material, with a hydrophilic membrane layer disposed on the side of the condensation membrane facing the first chamber, and a second evaporation layer disposed on the side of the condensation membrane facing the second chamber. The second chamber includes a top wall, which is the uppermost wall of the chamber. The top wall of the second chamber is a transparent wall. The material of the top wall of the second chamber may be the same as or different from the material of the condensation membrane. Light passes through the second chamber and is incident on the light-absorbing material of the first chamber. Water to be treated flows on both the first evaporation layer and the second evaporation layer. The water on the first evaporation layer is heated by the light-absorbing material to form water vapor. The water vapor releases heat on the condensation membrane to form condensate. The released heat is transferred to the second evaporation layer, heating the water on the second evaporation layer to form water vapor. The formed water vapor condenses on the top wall of the second chamber to form condensate.

[0006] As a preferred embodiment, the second evaporation layer is a material layer that is misty in a dry state and becomes transparent after absorbing moisture, with a light transmittance of >90% after absorbing water and a thickness of less than 0.1 mm.

[0007] As a preferred embodiment, the device comprises several chambers, arranged from bottom to top as the first chamber, the second chamber, ..., the nth chamber, where n ≥ 3. Light passes sequentially through the nth chamber ... the second chamber and is incident on the light-absorbing material of the first chamber. Adjacent chambers are separated by a condensation membrane. A hydrophilic membrane layer is disposed on one side of the condensation membrane, and an evaporation layer is disposed on the other side of the condensation membrane. For example, the condensation membrane between the nth chamber and the (n-1)th chamber has a hydrophilic membrane layer disposed on the side of the condensation membrane facing the (n-1)th chamber and an evaporation layer disposed on the side of the condensation membrane facing the nth chamber. The hydrophilic membrane layer materials on each condensation membrane may be the same or different, and the evaporation layer materials on each condensation membrane may be the same or different. Preferably, the hydrophilic membrane layer materials and the evaporation membrane layer materials are the same. The upper wall of the nth chamber at the top is called the top wall, which is made of a transparent material, preferably the same material as the condensation membrane below. A hydrophilic membrane layer is disposed on the inner wall of the top wall.

[0008] As a preferred embodiment, the hydrophilic membrane layer is coated onto the condensation membrane, and the contact angle between water vapor and the hydrophilic membrane layer after water vapor condenses into droplets is less than 10°.

[0009] As a preferred embodiment, the second evaporation layer is an electrospun material layer, and the preparation method includes the following steps: Two types of slurries are available, distinguished by whether the solute is soluble in water or ethanol. One slurry has PAN or modified PTFE as the solute and DMF as the solvent, with a solute mass fraction of 6% to 9%; the other slurry has PVP, PVA, or PEO as the solute and ethanol or water as the solvent, with a solute mass fraction of 6% to 9%; using the condensation membrane as a substrate and the mixed slurry as the electrospun material, electrospinning is performed to form the electrospun material layer.

[0010] As a preferred method, electrospinning uses a No. 22 needle, a spinning distance of 10cm, a spinning voltage of 15-20kV, a spinning slurry flow rate of 1.5-2mL / h, and adopts biaxial reciprocating spinning, spinning each 15×10cm area for 5-20min.

[0011] As a preferred embodiment, the condensation membrane is a PE membrane, PC membrane, or PET membrane with a thickness of less than 0.1 mm, and the hydrophilic membrane layer is formed by grafting hydrophilic functional groups onto the condensation membrane. The hydrophilic membrane layer is a silica sol membrane or a modified polyacrylic acid resin membrane with a thickness of less than 0.01 mm.

[0012] As a preferred embodiment, the chamber is provided with three chambers, namely, a first chamber, a second chamber, and a third chamber, from bottom to top. The first chamber and the second chamber are separated by a condensation membrane, and the second chamber and the third chamber are separated by a condensation membrane. Each condensation membrane, the bottom wall of the first chamber, and the top wall of the third chamber are all set at the same angle to the horizontal direction. Each chamber is provided with an inlet, a collection tank, and a drain. The water to be treated flows through the inlet to the corresponding evaporation layer and flows from top to bottom along the evaporation layer. During the flow, it evaporates to form water vapor, which condenses on the condensation membrane to form condensate. The condensate flows along the condensation membrane to the collection tank, and the evaporated water to be treated flows to the drain at the bottom of the chamber and is discharged from the chamber through the drain.

[0013] This invention also provides the application of the above-mentioned multi-effect solar water treatment device in seawater desalination and sewage treatment. During application, the influent flow rate is controlled according to the sunlight conditions. When the sunlight energy is ≥22 MJ / m², the influent flow rate is controlled accordingly. 2 / day, the water inflow to the first chamber is ≥8L / m 2 / day, the water inflow to the second chamber is ≥6L / m 2 / day, the water inflow to the third chamber is ≥4L / m 2 / day. Under other light intensities, adjust the water supply proportionally. The water intake for each distillation chamber should be fine-tuned based on the daily freshwater production; a freshwater to concentrated water ratio of 4 to 1 is optimal. Water supply should begin 1 hour before sunrise to ensure the evaporation membrane is fully wetted; water supply should cease 1 hour after sunset to allow the salt precipitated on the evaporation membrane surface to be rinsed and dissolved.

[0014] The technical effects of this invention include: 1. The device in this invention uses solar energy to generate heat and evaporate water to obtain fresh water resources, which is energy-saving and environmentally friendly. Through the stacking of multiple chambers, multi-level heat transfer and multi-effect heating are achieved. On the one hand, it makes full use of the solar energy absorbed by the light-absorbing material, and on the other hand, it accelerates the condensation of water vapor in the lower layer, reduces the inhibition of evaporation by water vapor supersaturation, and accelerates the evaporation of seawater in the upper layer, thereby improving the overall operating efficiency and water production.

[0015] 2. In this invention, a condensation membrane is used between adjacent chambers. The condensation membrane is made of a specific material to achieve optical transparency and efficient heat transfer. Water transfer is achieved by setting an electrospun material on the condensation membrane. During water transfer, the material is optically transparent and does not affect the incident light intensity. This ensures that the light can still maintain a certain light intensity after passing through several chambers and then be incident on the light-absorbing material. A specific process is used to make the electrospun material layer hazy in the dry state with low transparency, less than 70%. After absorbing water, the transparency increases to more than 90%.

[0016] 3. In this invention, the electrospinning layer makes the water layer uniform and the water film extremely thin, which can absorb the latent heat of phase change of the water vapor condensation of the next layer and evaporate efficiently, thereby improving the overall solar energy utilization efficiency and increasing the water production per unit area.

[0017] 4. This invention forms a hydrophilic film layer on the lower surface of the condensation membrane by chemical grafting, which modifies the lower surface from hydrophobic to hydrophilic. When water vapor condenses on the lower surface, it forms a water film instead of mist droplets, which improves light transmittance. The film layer formed by chemical grafting is extremely thin and stable, and does not affect heat transfer and light transmission.

[0018] 5. The present invention is an inclined plate structure, which is different from the common disk-type passive solar distiller where the light-absorbing surface is horizontal. The tilt angle can be set according to the latitude of the equipment installation location to increase the total intensity of sunlight received throughout the year. Moreover, the tilt angle is conducive to the spontaneous flow, diffusion and wetting of seawater from top to bottom, avoiding crystallization due to excessive local salt concentration.

[0019] 6. This invention can be set up with 3 or more multi-stage multi-effect chambers, and the water supply of each chamber can be controlled separately. It can be adjusted according to the light intensity to reduce heat loss caused by seawater heating, and can effectively flush out crystalline salts to avoid scaling.

[0020] 7. The device in this invention can increase the efficiency of solar distillation to over 110% through multi-effect heat utilization, breaking through the theoretical limit of single-stage solar distillation. The specific calculation method for the solar distillation efficiency η is as follows: η = (m × h) ÷ P; where m is the daily water production of the device, in kg / m³. 2 Calculated based on the area of ​​the light-absorbing material in the first chamber; h is the enthalpy of vaporization of water, in kJ / kg, which can be taken according to the actual operating temperature of the device; P is the total light intensity of the day, in MJ / m². 2 . Attached Figure Description

[0021] Figure 1 Structural diagram of the device in this invention;

[0022] Figure 2 The structural diagram of the first condensation membrane. Detailed Implementation

[0023] The present invention will be further explained in detail below with reference to the accompanying drawings and specific embodiments, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. The directional terms such as "upper" and "lower" used below refer to the positional relationship of the device in its use state.

[0024] The multi-effect solar water treatment device of this invention, such as Figure 1 As shown, the device comprises 2 to n chambers stacked sequentially, where n > 2. The number of chambers is determined based on the heat loss during the step-by-step heat transfer process. Taking the three chambers shown in the attached figure as an example, the specific structure of the device is described. From bottom to top, the device consists of a first chamber 1, a second chamber 2, and a third chamber 3. A first condensation membrane 8 is disposed between the first chamber 1 and the second chamber 2, and a second condensation membrane 9 is disposed between the second chamber 2 and the third chamber 3. The top wall of the third chamber 3 is a third condensation membrane 10. The first condensation membrane 8, the second condensation membrane 9, and the third condensation membrane 10 may have the same or different structures or materials, but they are all transparent and waterproof materials. The condensation membrane can be a rigid plate, such as a glass plate, or a polymer material with a certain degree of flexibility.

[0025] The first chamber 1, the second chamber 2, and the third chamber 3 are respectively equipped with a first evaporation layer 14, a second evaporation layer 4, and a third evaporation layer. All three evaporation layers are connected to a water source to be treated. The water absorbs heat and evaporates into water vapor as it flows along the evaporation layers. The first evaporation layer 14 is located on the bottom wall of the first chamber 1. A light-absorbing material is also located on the bottom wall of the first chamber 1. This light-absorbing material absorbs sunlight and converts it into heat. The light-absorbing material and the first evaporation layer 14 can be configured in the following ways: a) the light-absorbing material and the first evaporation layer 14 are the same material, such as black non-woven fabric or black paper; b) the light-absorbing material is located below the first evaporation layer 14, where the first evaporation layer 14 is a transparent hydrophilic material, and the light-absorbing material is a black metal, black carbon-based material, or other strong light-absorbing material; c) the light-absorbing material is incorporated into the first evaporation layer 14, such as light-absorbing particles distributed in a hydrophilic material or a nanoporous material sprayed with black particles. When the light-absorbing material absorbs sunlight or other light, it heats the water in the first evaporation layer 14, causing the water to evaporate and form water vapor. The second evaporation layer 4 and the third evaporation layer are respectively disposed on the side of the first condensation film 8 facing the second chamber 2 and the second condensation film 9 facing the third chamber 3. The second evaporation layer 4 and the third evaporation layer are made of transparent hydrophilic materials. On the lower surface of the condensation film, such as the side of the first condensation film 8 facing the first chamber 1, the side of the second condensation film 9 facing the second chamber 2, and the side of the third condensation film 10 facing the third chamber 3, a hydrophilic film layer 5 is disposed. The contact angle between this hydrophilic film layer 5 and water is less than 10°. Water droplets can quickly spread into a thin water layer upon contact with this film layer, without scattering incident light, thus avoiding the influence of droplets on incident light. The first evaporation layer 14, the second evaporation layer 4, and the third evaporation layer are preferably made of hydrophilic materials.

[0026] The first chamber 1, the second chamber 2, and the third chamber 3 are all flat rectangular structures, and the chambers are set at an angle. This setting facilitates light to enter the light-absorbing material and also facilitates water flow along the evaporation layer under the action of gravity.

[0027] The second evaporation layer 4 and the third evaporation layer are electrospun materials. The preparation method of this film layer is as follows: a) Preparation of slurry: There are two types of slurry to choose from, distinguished by whether the solute is soluble in water or ethanol. One type of slurry uses PAN or modified PTFE as the solute and DMF as the solvent, with a mass fraction of 6% to 9%; the other type of slurry uses PVP, PVA, or PEO as the solute and ethanol or water as the solvent, with a mass fraction of 6% to 9%; b) The slurry is heated and stirred in a water bath at 50 to 70°C for 1 hour to allow the polymer powder to precipitate. Complete dissolution; c. Electrospinning: Using a condensation membrane as a substrate, biaxial reciprocating spinning is performed on the condensation membrane at a flow rate of 1.5-2 mL / h, with each 15×10 cm area spinning for 5-10 min. The spinning parameters are: No. 22 needle, spinning distance 10 cm, and spinning voltage 15-20 kV. Finally, an electrospinning layer is formed on the condensation membrane. This electrospinning layer is hazy and has low transparency in the dry state. After absorbing moisture, the transparency is higher than 90%, so it does not affect the light transmittance of the device in the water supply state.

[0028] The hydrophilic film layer 5 is a superhydrophilic material thin layer on the condensing membrane, with hydrophilic functional groups adsorbed onto it in the form of chemical grafting. The thickness of the thin layer is <0.01 mm. It can be a silica sol membrane. The preparation method is as follows: a) Prepare the coating solution: Mix water, ethanol and silica sol to form a coating solution, wherein the mass fraction of water is 84% ​​to 84.5%, the mass fraction of ethanol is 15%, and the mass fraction of silica sol (nano silica) is 0.5% to 1%; b) Apply by scraping: Apply the coating to the surface of the condensing membrane using a 10-20 μm extrusion wire rod wet film coater. The condensing membrane is PE, PC, PET, etc. After coating, let it stand and dry. Use water and ethanol as solvents to dissolve the silica sol to form a coating solution, which reduces the contact angle between the coating solution and the condensing membrane, so that the coating solution is uniformly coated on the condensing membrane. The silica sol has abundant hydroxyl functional groups, which combine with the functional groups on the polymer of the condensing membrane to form a chemical graft, forming a dense and firm thin layer on the condensing membrane. The preferred thickness of the condensation film is 0.25 mm.

[0029] This invention achieves capillary water transport by setting an electrospun layer on a condensation membrane, and the water transport process does not affect light absorption. The transparency of the electrospun layer differs between dry and wet states, and the incident light intensity can be adjusted by utilizing this difference in transparency. When it is necessary to reduce the incident light intensity, one or more chambers in the upper layer are de-watered, the electrospun layer is dry, and the transparency is low, thus reducing the incident light intensity. The invention employs multiple chambers, which on the one hand allows for multi-stage utilization of heat, increasing the water treatment capacity, and on the other hand allows for adjustment of the number of de-watered chambers, thereby adjusting the incident light intensity. Situations requiring light intensity adjustment include wastewater treatment processes where certain components volatilize at high temperatures. To prevent this volatilization, it is necessary to control the evaporation temperature of the water to be treated; in this case, the water temperature can be adjusted by controlling the incident light intensity. In this invention, the hydrophilic membrane layer 5 is formed on the condensation membrane by chemical grafting. If this membrane layer is not provided, water vapor will condense on the condensation membrane and form droplets, and the light incident on the condensation membrane will be scattered, thus affecting the intensity of the incident light. Forming the membrane layer by chemical grafting functional groups can increase the stability of the hydrophilic membrane layer 5 and the condensation membrane surface and prevent it from falling off.

[0030] In this invention, the chamber is mounted on a support 7, which supports and fixes the chamber, allowing it to be tilted. The tilt angle is set according to the latitude and longitude of the area where the device is located. If the device is located north of 20°N or south of 20°S, the tilt angle should correspond to the latitude. At this tilt angle, the device receives maximum sunlight energy throughout the year, making full use of light. If the device is located between 20°N and 20°S, the tilt angle should be set at 20°. At this tilt angle, seawater can flow downwards under gravity, fully wetting the evaporation membrane.

[0031] In this invention, a heat insulation layer 6 is provided on the outer side of the bottom wall of the first chamber 1 at the bottom layer to prevent heat from diffusing out of the chamber. For the same reason, a heat insulation layer 6 is provided on the outer wall of each chamber. The chambers can be integrated, that is, the same chamber is divided into multiple chambers by a condensation film, or they can be independent of each other, such as the first chamber 1 and the second chamber 2 being independent of each other. During installation, the top wall of the first chamber 1 and the bottom wall of the second chamber 2 are attached together or attached together in the middle through a heat-conducting layer. The condensation film is formed by attaching the top wall of the first chamber 1 and the bottom wall of the second chamber 2 together. This arrangement allows for the free removal or replacement of the intermediate chambers.

[0032] When the present invention has multiple chambers, the required number of chambers are stacked on top of the third chamber 3. A condensation membrane is provided between adjacent chambers. An electrospun layer is provided on the upper surface of the condensation membrane, and a hydrophilic membrane layer 5 is provided on the lower surface of the condensation membrane. Each chamber is provided with an inlet 11, an outlet 12, and a collection tank 13. The inlet 11 is located on the upper end face of the chamber near the evaporation layer. The water to be treated flows into the corresponding evaporation layer through the inlet 11. As a preferred embodiment, a diverter is provided at the end to drip the water to be treated onto the evaporation layer, which then flows downwards along the evaporation layer. The outlet 12 is provided on the lower end face of the chamber, preferably at the lower edge of the evaporation layer, to collect the water flowing down the evaporation layer. The collection tank 13 is located on the inner wall of the lower end wall of the chamber to collect the condensate flowing along the condensation membrane.

[0033] The device in this invention can be used for seawater desalination or wastewater treatment. Taking seawater desalination as an example, the operation process of the device in this invention is described. For clarity, it is described in sections, and the numbers before the sections are not operational steps:

[0034] Seawater is delivered to the corresponding chambers through a diversion dripper. The seawater drips onto the evaporation layer and flows along the evaporation layer under the action of gravity. It also diffuses to the surroundings through the capillary action of the evaporation layer, wetting the entire evaporation layer.

[0035] b. The seawater in the first chamber 1 is heated to form water vapor under the action of light-absorbing material;

[0036] c. Water vapor diffuses upwards to the lower surface of the first condensation film 8 and condenses into water, and the released heat continues to be transferred upwards to the second chamber 2;

[0037] The evaporation layer of the second chamber 2 absorbs the heat transferred from the first chamber 1, evaporates to form water vapor, and then condenses into water on the second condensation film 9, releasing heat. The heat continues to be transferred upward to the third chamber 3.

[0038] The water in the third chamber 3 absorbs heat and evaporates into water vapor, which then condenses back into water on the third condensation membrane 10.

[0039] The condensate flows downward along the first condensation membrane 8, the second condensation membrane 9, or the third condensation membrane 10 to the water collection tank 13. The water in the water collection tank 13 is discharged through the discharge pipe to obtain pure water.

[0040] The water treatment capacity of the device in this invention is: when the light energy is ≥22MJ / m 2 / day, the water inflow to chamber 1 is ≥8L / m 2 / day, the water inflow to the second chamber 2 is ≥6L / m 2 / day, the water inflow to the third chamber 3 is ≥4L / m 2 / day. Under other light intensities, adjust the water supply proportionally. The water intake of each distillation chamber should be fine-tuned according to the daily freshwater production, with a freshwater:concentrate ratio of (4-1):1 being the optimal operating condition. The water supply should begin 1 hour before sunrise to ensure the evaporation layer is fully moistened; the water supply should end 1 hour after sunset to allow the salt precipitated on the evaporation membrane surface to be rinsed and dissolved.

[0041] Example

[0042] The device comprises three chambers. Each chamber is a rectangular prism, 20cm long, 10cm wide, and 4cm high. Two condensation films are positioned along the height of each chamber, separating them into three separate chambers. Each chamber is 1cm high. The bottom wall of the first chamber (1) is 1cm thick. The top wall of the third chamber (3), along with the first condensation film (8) and the second condensation film (9), is a 0.2mm transparent PE film. Figure 2 As shown, a second evaporation layer 4 and a third evaporation layer are respectively disposed on the upper surfaces of the first condensation membrane 8 and the second condensation membrane 9, and a hydrophilic membrane layer 5 is disposed on the lower surfaces. The second evaporation layer 4 and the third evaporation layer are made of electrospun materials, the first evaporation layer 14 is made of black cotton cloth, the inclination angle of the chamber is 30°, and the effective dimensions of the first evaporation layer 14, the second evaporation layer 4, the third evaporation layer, the first condensation membrane 8, the second condensation membrane 9, and the third condensation membrane 10 are all 19cm × 9cm.

[0043] The method for loading the second evaporation layer 4 onto the first condensing membrane 8 or the third evaporation layer onto the second condensing membrane is as follows: A condensing membrane (PE membrane) cut to the appropriate size is attached to a grounded electrode plate. The spinning slurry is a 6% wt% PAN solution in DMF. A No. 22 needle is used, the spinning distance is 10 cm, the voltage is 12 kV, the flow rate of the spinning slurry is 2 mL / h, and a micro-pump is used for control. Biaxial reciprocating spinning is used, with the X and Y axes corresponding to the size of the PE membrane. The spinning time is 10 min.

[0044] After preparation and drying for 1 hour, the condensed membrane was then fully immersed in water. The transmittance before and after water absorption was measured to be 76% and 91%, respectively. Within a certain parameter range, the shorter the spinning time, the lower the spinning slurry concentration, and the slower the flow rate, the thinner the electrospun membrane obtained, and the higher the transmittance after water absorption, but the water absorption becomes worse.

[0045] Method for loading superhydrophilic membranes onto the first condensing membrane 8, the second condensing membrane 9, or the third condensing membrane 10: At room temperature (15°C), the coating solution ratio is 84% ​​water, 15% ethanol, and 1% silica sol (wt%), where the silica particle size is 5–20 nm. Stir thoroughly for 60 minutes before use. Place the condensing membrane (PE membrane) on a flat workbench. The loading surface of the first condensing membrane 8 and the second condensing membrane 9 should face away from the electrospun membrane, while the loading surface of the third condensing membrane 10 should face one side of the membrane. During installation, evenly drop 5 ml of coating solution onto one end of the PE membrane, then use a 15 μm extrusion-type wire rod wet film coater to evenly coat the membrane to the other end. Excess coating solution is scraped directly off the PE membrane, and then allowed to dry. The test results showed a contact angle <5°, while the contact angle before modification was approximately 105°.

[0046] After assembling the apparatus, a micro-pump was used to supply water to each chamber, with two diverting droplets per chamber. The water supply rates for chamber 1, chamber 2, and chamber 3 were 23 mL / h, 17 mL / h, and 12 mL / h, respectively. Experimental conditions: Laboratory environment, room temperature 15℃, xenon lamp light source, average light intensity reaching 1 kW / m². 2 The raw water used for testing was a NaCl solution with a wt% concentration of 3.5%.

[0047] Test results: The micro-pump was turned on to supply water first, and the xenon lamp light source was turned on after 30 minutes. After 1 hour of stable operation, the water production rate was tested. The water production rates of the first chamber, the second chamber 2, and the third chamber 3 were 14 mL / h, 10 mL / h, and 7 mL / h, respectively, with a total light utilization rate of ≈120.9%.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multi-effect solar water treatment device, characterized in that: The device includes at least a first chamber and a second chamber, which are separated by a condensation membrane. The first chamber includes a bottom wall, and a first evaporation layer is disposed on the bottom wall of the first chamber. The first evaporation layer is a light-absorbing material or the first evaporation layer is connected to a light-absorbing material. The light-absorbing material absorbs light and converts it into heat to heat the water on the first evaporation layer. The condensation membrane is a transparent material, and a hydrophilic membrane layer is disposed on the side of the condensation membrane facing the first chamber, and a second evaporation layer is disposed on the side of the condensation membrane facing the second chamber. Water to be treated flows through both the first and second evaporation layers. When light is incident on the light-absorbing material of the first chamber, the water on the first evaporation layer is heated by the light-absorbing material to form water vapor. The water vapor releases heat on the condensation film to form condensate. The released heat is transferred to the second evaporation layer, heating the water on the second evaporation layer to form water vapor. The formed water vapor condenses on the top wall of the second chamber to form condensate. The second chamber includes a top wall, which is a transparent wall. The material of the top wall of the second chamber is the same as or different from the condensation film material. Light passes through the second chamber and is incident on the light-absorbing material of the first chamber. The second evaporation layer is a material layer that is translucent in a dry state and becomes transparent after absorbing moisture. After absorbing water, the light transmittance is >90%, and the thickness of the second evaporation layer is less than 0.1mm.

2. The multi-effect solar water treatment device according to claim 1, characterized in that: The device has several chambers, namely the first chamber, the second chamber, ... the nth chamber, where n ≥ 3. Light passes through the nth chamber ... the second chamber and is incident on the light-absorbing material of the first chamber. Adjacent chambers are separated by a condensation membrane. A hydrophilic membrane layer is provided on one side of the condensation membrane, and an evaporation layer is provided on the other side of the condensation membrane. The hydrophilic membrane layer materials on each condensation membrane may be the same or different, and the evaporation layer materials on each condensation membrane may be the same or different.

3. The multi-effect solar water treatment device according to claim 1, characterized in that: The hydrophilic membrane layer is coated onto the condensation membrane. After water vapor condenses into droplets on the hydrophilic membrane layer, the contact angle between the water vapor and the hydrophilic membrane layer is less than 10°.

4. The multi-effect solar water treatment device according to claim 1, characterized in that: The second evaporation layer is an electrospun material layer, and the preparation method includes the following steps: Prepare electrospinning sizing agents. Choose one of the following: Sizing agent one: use DMF as solvent and PAN or modified hydrophilic PTFE as solute, with a solute mass fraction of 6%~9%; Sizing agent two: use ethanol or water as solvent and PVP, PVA, or PEO as solute, with a solute mass fraction of 6%~9%. Electrospinning: Using the condensation membrane as a substrate and the slurry one or slurry two as the electrospinning material, electrospinning is performed to form the electrospinning material layer.

5. The multi-effect solar water treatment device according to claim 4, characterized in that: Electrospinning uses a No. 22 needle, a spinning distance of 10cm, a spinning voltage of 15~20kV, a spinning slurry flow rate of 1.5~2mL / h, and a biaxial reciprocating spinning method. Each 15×10cm area is spun for 5~20min.

6. The multi-effect solar water treatment device according to claim 1, characterized in that: The condensation membrane is made of PE, PC or PET film, and the hydrophilic membrane layer is formed by grafting hydrophilic functional groups onto the condensation membrane. The hydrophilic membrane layer is a silica sol membrane and the thickness of the hydrophilic membrane layer is less than 0.01 mm.

7. The multi-effect solar water treatment device according to claim 1, characterized in that: The method for preparing the hydrophilic film layer includes the following steps: a. Preparation of coating solution: Mix water, ethanol, and silica sol to form a coating solution, wherein the mass fraction of water is 84%~84.5%, the mass fraction of ethanol is 15%, and the mass fraction of silica sol is 0.5%~1%; b. Scraping: Apply the coating to the surface of the condensation film using a 10~20μm extrusion-type wire bar wet film applicator.

8. The multi-effect solar water treatment device according to claim 1, characterized in that: The chamber is configured with three chambers, namely, the first chamber, the second chamber, and the third chamber, from bottom to top. The first chamber and the second chamber are separated by a first condensation membrane, and the second chamber and the third chamber are separated by a second condensation membrane. Each condensation membrane, the bottom wall of the first chamber, and the top wall of the third chamber are all set at the same angle to the horizontal direction. Each chamber is equipped with a water inlet, a water collection tank, and a water outlet. The water to be treated flows through the water inlet to the corresponding evaporation layer and flows from top to bottom along the evaporation layer. During the flow, it evaporates to form water vapor, which condenses on the condensation membrane to form condensate. The condensate flows along the condensation membrane to the water collection tank. The evaporated water to be treated flows to the water outlet at the bottom of the chamber and is discharged from the chamber through the water outlet.

9. The application of the multi-effect solar water treatment device as described in claim 1 in seawater desalination and sewage treatment.

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