CN109292874B

CN109292874B - Solar still for collecting condensed water based on capillary action

Info

Publication number: CN109292874B
Application number: CN201811289847.0A
Authority: CN
Inventors: 杨诺; 刘欢; 彭桂龙; 胡志响
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2018-10-31
Filing date: 2018-10-31
Publication date: 2020-08-04
Anticipated expiration: 2038-10-31
Also published as: CN109292874A

Abstract

The invention belongs to the technical field of water treatment and discloses a solar distiller for collecting condensed water based on capillary action. This solar still includes one or more vertical superimposed solar still substructure in proper order, and wherein, single solar still substructure includes bottom uncovered water tank, water catch bowl, condensing plate and water storage baffle, bottom uncovered water tank portion contains the reservoir, the condensing plate contains condensation surface and vertical drop face. The solar distiller disclosed by the invention can realize multi-stage utilization of waste heat of water vapor on the basis of fully utilizing solar energy resources, and can quickly absorb and transport condensed water through capillary action and collect the condensed water to condense the condensed water, so that the efficiency of a system is reduced by preventing water drops from scattering sunlight, the utilization rate of solar energy is further improved on the basis of obviously improving the efficiency of water purification treatment, and the solar distiller further has the advantages of more compact structure, convenience in operation and control, stronger environmental adaptability, low water purification cost and the like.

Description

Solar still for collecting condensed water based on capillary action

Technical Field

The invention belongs to the technical field of water treatment such as solar seawater desalination/sewage purification and the like, and particularly relates to a solar distiller for collecting condensed water based on capillary action.

Background

Drinking water is one of the major global problems, most health problems being due to lack of clean drinking water. In recent decades, insufficient rainfall around the world has led to increased water salinity. Environmental pollution further exacerbates the lack of clean fresh water. One of the most important means for solving the problem of lack of fresh water is seawater desalination. Generally, seawater desalination technologies are roughly divided into two categories: thermal desalination technology and membrane desalination technology. In the thermal desalination technology, fresh water is obtained by heating seawater to evaporate water and condense steam, and these technologies are various and include multi-effect distillation (MED), multi-stage flash evaporation (MSF), Thermal Vapor Compression (TVC), Mechanical Vapor Compression (MVC), humidification-dehumidification (HDH), and solar still. The membrane desalination technology utilizes a selective permeation membrane to separate salt and water. Membrane desalination typically uses a pressure driven brine separation process that does not require phase change to occur, and membrane desalination technologies mainly include Reverse Osmosis (RO) technology and Electrodialysis (ED) technology.

Among them, the solar seawater desalination technology has many advantages compared with the traditional technology using high-grade energy such as fuel oil, electric energy and the like. The solar energy is not dependent on remote transportation of energy fuel, is hardly influenced by geographical positions, has the energy cost of 0, and has good popularity; meanwhile, solar energy is a clean renewable energy source, is environment-friendly and pollution-free, and accords with the current global trend of enhancing environmental protection. In addition to desalination of seawater, sewage purification is also an important way to supplement clean fresh water. The traditional distiller comprises a wedge-shaped cavity, seawater is filled in the wedge-shaped cavity, the temperature of the seawater and the temperature of the bottom of the seawater rise through solar radiation absorption, the seawater is promoted to evaporate, water vapor can be condensed on a glass cover plate and attached to glass, and the condensed water flows downwards along the glass under the action of gravity and then enters a collecting tank, so that the evaporation and desalination process is completed. Based on the above-mentioned conventional distiller principle, the prior art has developed many different kinds of solar evaporators, such as a step evaporator and an inclined core type evaporator, but the solar energy utilization efficiency of the conventional evaporator is generally below 50% due to a large amount of heat loss. Meanwhile, in the prior art, nanoparticles such as nano metal particles, nano metal oxides, nano carbon materials and the like are added into seawater/sewage, the absorption efficiency (low-grade heat energy) and the heat transfer performance of a system are remarkably improved through the high heat conductivity of the nanoparticles, and the nanofluid has high absorption rate to solar energy, so that the fresh water yield of the system is effectively increased through the nanofluid formed by the nanoparticles and the seawater/sewage.

However, there are still many problems with nanotechnology based distillers. On the one hand, the water vapor in the distiller is directly condensed on the glass cover plate to form condensed water, and the condensed water scatters the irradiated sunlight, so that the utilization of solar energy is greatly reduced, and meanwhile, the condensed water is dripped into a seawater or sewage container under the action of gravity, so that the condensed water recovery effect is poor. On the other hand, the prior art adopts a single-stage distiller, cannot realize multi-stage utilization of solar energy, and cannot realize heat dissipation utilization of seawater or sewage heated by solar energy, and although the evaporation efficiency is 80-90%, the comprehensive efficiency of the system is only less than 30%. Accordingly, there is a need in the art for further improvements or improvements to better achieve efficient use of solar energy to drive water evaporation and accelerated condensation to meet the needs of modern clean drinking water.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a solar distiller for collecting condensed water based on capillary action, which can realize multi-stage utilization of waste heat of water vapor on the basis of fully utilizing solar energy resources by combining recycling of various kinds of sewage or seawater and fully utilizing the specific working condition requirements of solar energy for water purification, and can quickly absorb and transport the condensed water and collect the condensed water through capillary action, thereby obviously improving the efficiency of water purification treatment.

In order to achieve the above object, the present invention provides a solar still for collecting condensed water based on capillary action, which is characterized by comprising one or more vertically sequentially stacked solar still substructures, wherein a single solar still substructure comprises a bottom layer uncovered water tank, a water collection tank, a condensation plate and a water storage baffle; wherein the content of the first and second substances,

the bottom layer uncovered water tank is a base of the single solar distiller substructure, a liquid storage tank is arranged in the bottom layer uncovered water tank, and nano fluid or water-containing porous material is arranged in the liquid storage tank and used for absorbing sunlight and converting solar energy into heat energy so as to evaporate liquid into water vapor;

the condensation plate covers the uncovered water tank and is not contacted with the liquid in the liquid storage tank, the condensation plate comprises a condensation surface and a vertical dropping surface, the surfaces of the condensation surface and the vertical dropping surface are provided with capillary structures, the vertical dropping surface is contacted with the inner wall of the inner baffle plate of the water collecting tank, and the capillary force of the vertical dropping surface is greater than that of the condensation surface; meanwhile, the waste heat energy of the water vapor is transferred to the solar distiller subsystem on the upper layer through the condensing surface to realize the multi-stage utilization of the energy, and

the water collecting tank is arranged on the side surface of the uncovered water tank or the water storage baffle and is used for collecting the condensed water from the dripping surface.

Furthermore, the capillary structure is a micron line or a nano line which is laid on the surface of the condensation surface and has a porous structure by adopting the processes of deposition, spin coating, spray coating, rod coating, weaving, pressure welding and the like.

Further, the capillary structure is a transparent metal organic framework material with a porous structure.

Further, the diameter of the micron line or the nano line is less than 100 microns; the pore diameter of the porous structure formed by the micron lines or the nano lines is less than 10 millimeters.

Furthermore, the condensation surface is horizontally arranged on the uncovered water tank or the water storage baffle, and the dripping surface and the condensation surface are connected or bonded into a whole in a direct lap joint mode.

Further, the dripping surface is arranged at the peripheral edge or partial edge of the bottom surface of the condensing surface; the vertical dropping surface is of an inverted pyramid structure with the bottom folded downwards, preferably, the vertical dropping surface is of a triangular structure with the bottom edge attached to the bottom surface of the condensation surface or of a plurality of triangular structures arranged in a horizontal array, so that liquid drops can be formed at the sharp position of the bottom of the vertical dropping surface.

Furthermore, the cross sections of the uncovered water tank and the water storage baffle are rectangular, polygonal or circular, and are matched with the shape structure of the condensation plate.

Furthermore, the height of the uncovered water tank and the water storage baffle is less than or equal to 5 cm.

Furthermore, at least one side wall of the uncovered water tank is provided with a water inlet, and at least one side wall of the uncovered water tank is provided with a water outlet, preferably, each side wall of the uncovered water tank is provided with the water inlet and the water outlet; the water storage baffle is characterized in that a water inlet is formed in at least one side wall of the water storage baffle, a water outlet is formed in at least one side wall of the water storage baffle, and the water inlet and the water outlet are preferably formed in each side wall of the water storage baffle.

Further, the liquid storage tank is of a tank body structure for storing seawater, sewage, nanofluid or a water-containing porous material.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. the solar distiller of the invention redesigns the spatial layout and structure of the whole distiller device by closely combining the reutilization of various sewage or seawater and fully utilizing the specific working condition requirement of solar heat energy for water purification, particularly improves the condensed water system thereof from the aspects of specific structure composition, equipped condensing surface and dripping surface, action mechanism of capillary structure arranged on the condensing surface and the dripping surface, installation and arrangement between the condensed water system and other components, correspondingly realizes the multi-stage utilization of water vapor waste heat on the basis of fully utilizing solar energy resources, simultaneously quickly absorbs and transports condensed water through capillary action and gathers the condensed water, prevents water droplets from scattering sunlight to reduce the system efficiency, and further improves the utilization rate of solar energy on the basis of remarkably improving the efficiency of water purification treatment, but also has the advantages of more compact structure, convenient operation and control, stronger environmental adaptability, low water purification cost and the like.

2. According to the solar distiller, the capillary structure is arranged on the surface of the condensation surface of the solar distiller to accelerate the absorption and conduction of water vapor and prevent the water vapor from being condensed and gathered on the plate surface directly, so that the system efficiency is reduced by preventing water drops from scattering sunlight, and the utilization rate of solar energy is improved.

3. According to the solar distiller, the capillary force of the vertical dropping surface is not weaker than that of the condensing surface, in this way, the condensing surface is used for rapidly condensing water vapor from the liquid storage tank and transporting condensed water to the vertical dropping surface through the capillary action, and the vertical dropping surface rapidly absorbs the condensed water transported by the condensing surface through the capillary action and collects the condensed water, so that the water vapor is prevented from directly collecting on the condensing surface.

4. The solar distiller comprises a plurality of solar distiller substructures, the thickness of the solar distiller substructures can be set to be thin, the previous layer of substructure can fully absorb and utilize the waste heat of water vapor of the next layer of substructure to accelerate the water evaporation speed, and meanwhile, the superposition of the multiple layers of substructures has the characteristics of compact structure, capability of effectively reducing the heat dissipation area of the device and reducing the heat loss of the system.

5. The solar distiller of the invention adopts single-stage and multi-stage structures, which can effectively recover latent heat of condensation, and make the absorbed heat be used for many times, thereby greatly improving the system yield.

Drawings

FIG. 1 is an exploded view of a solar still according to an embodiment of the present invention;

FIG. 2 is a schematic view of a cold plate of a solar still according to an embodiment of the present invention;

FIG. 3 is a schematic view of a sump of a solar still according to an embodiment of the present invention;

FIG. 4 is a schematic view of a bottom uncovered water tank of a solar still according to an embodiment of the present invention;

FIG. 5 is a schematic view of a water storage baffle of a solar still according to an embodiment of the present invention;

fig. 6 is a schematic structural view of a liquid storage tank of the solar still according to the embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Referring to fig. 1 to 6, the embodiment of the invention provides a solar still for collecting condensed water based on capillary action, which comprises one or more vertically sequentially stacked solar still substructures, wherein a single solar still substructure comprises a bottom layer uncovered water tank 1, a water collection tank 2, a liquid storage tank (stored water or nano-fluid or porous material containing water) 3, a condensation plate 4 and a water storage baffle plate 5. Wherein, the bottom layer uncovered water tank 1 is a base of the distiller, and the inside of the bottom layer uncovered water tank is provided with a liquid storage tank 3 which is used for absorbing sunlight and evaporating water. The condensation plate 4 is covered on the uncovered water tank 1 and is not contacted with the liquid in the liquid storage tank 3, and is used for condensing the water vapor from the liquid storage tank 3 and transporting the condensed water, and the condensation plate 4 is made of transparent material. The water collecting tank 2 is installed at a side of the uncovered water tank 1 or the water storage baffle 5 for collecting the condensed water from the condensing panel 4. A water storage baffle 5 is placed above the condensation plate 4. The contact part of the water storage baffle 5 and the condensation plate 4 is sealed by silicone adhesive or other materials, and the liquid storage tank 3 placed in the water storage baffle 5 is prevented from leaking from the gap. The distiller comprises a bottom layer uncovered water tank 1, a water collecting tank 2, a liquid storage tank 3, a condensation plate 4 and a water storage baffle plate 5, wherein the water storage baffle plate 5 and the liquid storage tank 3 are used for cooling the condensation plate 4, and the condensation effect is prevented from being reduced due to overheating of the condensation plate 4. When the solar still comprises a plurality of substructures, the solar still comprises a bottom layer uncovered water tank 1, a water collection tank 2, a liquid storage tank 3, a condensation plate 4 and a water storage baffle 5, wherein the liquid storage tank 3 in the water storage baffle 5 is used for cooling the condensation plate 4 and is used as a steam source of the stage. The number of the substructures of the solar distiller is determined according to requirements and working conditions. The condensing plate 4 has good capillary action and keeps transparent, can effectively condense vapor and transport condensed water to the water collecting tank 2, and simultaneously prevents the surface of the condensing plate from fogging to block sunlight from entering the system.

Referring to fig. 1 to 6, the condensation plate 4 includes a condensation surface 401 having a capillary structure on the surface and a dripping surface 402, wherein the dripping surface 401 contacts (overlaps) the inner wall 202 of the inner baffle of the water collection tank 2. The droplet plane 402 and the condensation plane 401 may be of the same material or different materials, but the capillary force of the droplet plane 402 is not weaker than that of the condensation plane 401. The dripping surface 402 and the condensing surface 401 are in contact with each other in a physical overlapping manner or in a combined manner. The condensation surface 401 is horizontally placed on the uncovered water tank 1 or the water storage baffle 5, is made of transparent material, and has strong capillary force. The drip surface 402 is vertically disposed and is disposed around the peripheral edge or a portion of the edge of the condensation surface 401. The preferred configuration of the drip surface 402 is one or more triangles to facilitate the formation of drops at the lower, sharp point of the drip surface, thereby facilitating the collection of the condensate. Meanwhile, the height of the dripping surface is preferably about 1-2cm lower than the height of the uncovered water tank 1 and the water storage baffle 5. When the hot vapour from the reservoir 3 contacts the condensation surface 401, the vapour condenses at the surface into a liquid which is transported by capillary action from the condensation surface 401 towards the droplet surface 402. The liquid collected on the lower portion of the dropping surface 402 forms a water flow or water drops toward the water collecting tub 2 by gravity. The water collecting tank 2 is fixedly connected to the uncovered water tank 1 and the water storage baffle 5, and a water outlet 201 is formed in the water collecting tank 2 and used for discharging collected condensed liquid out of the distiller.

The condensation plate 4 covers the uncovered water tank 1 and is not contacted with the liquid in the liquid storage tank 3, the condensation plate 4 comprises a condensation surface 401 and a dripping surface 402, the surfaces of the condensation surface 401 and the dripping surface 402 are both provided with capillary structures, the dripping surface 402 is contacted with the inner baffle inner wall 202 of the water collecting tank 2, the capillary force of the dripping surface 402 is not weaker than that of the condensation surface 401, in this way, the condensation surface 401 is used for rapidly condensing the water vapor from the liquid storage tank 3 and transporting the condensed water to the dripping surface 402 through the capillary action, and the dripping surface 402 rapidly absorbs the condensed water transported by the condensation surface 401 through the capillary action and collects the condensed water, so that the water vapor is prevented from directly collecting on the condensation surface 401; meanwhile, the waste heat energy of the water vapor is transferred to the substructure of the solar still on the upper layer through the condensation surface 401, so that the multi-stage utilization of the energy is realized.

The capillary structure of the condensation plate 4 may be fabricated by attaching microwires and nanowires to materials such as a transparent glass plate, an acrylic plate, and a plastic film by using deposition, spin coating, spray coating, bar coating, pressure welding, and the like, thereby forming a porous transparent capillary plate. Or the materials such as the micron wires and the nano wires are made into transparent capillary porous films and are adhered to the materials such as glass plates, acrylic plates, plastic films and the like. Or a transparent metal organic framework based porous material, and the like. The microwire and the nanowire can be organic materials such as cellulose and can also be inorganic materials such as silver nanowires. The diameter of the microwire or the nanowire is preferably less than 100 micrometers. The micrometer wires, the nanometer wires and the transparent metal organic framework are preferably made of hydrophilic materials. The pore diameter formed by the micron line and the nano line is preferably less than 10 mm.

As shown in fig. 4 and 5, the uncovered water tank 1 and the water storage baffle 5 can be rectangular, polygonal or other shapes, and are matched with the shape structure of the condensation plate 4, preferably rectangular structure. And at least one side wall is provided with a water inlet 101 and a water inlet 502, and the same side or the other side is provided with a water outlet 102 and a water outlet 501. Preferably, each side wall is provided with a water inlet 101, a water inlet 502, a water outlet 102 and a water outlet 501 for rapidly inputting sewage or seawater to be purified and discharging high-concentration seawater or sewage, and the structural form and the number of the side walls can be designed according to actual requirements. The uncovered water tank 1 is located at the bottom of the distiller and a water storage baffle 5 is located above each stage of condensing panels 4. The water storage baffle 5 is hermetically connected with the condensing plate 4 below the water storage baffle, and the water storage baffle and the condensing plate are combined into a water tank. The liquid storage tank 3 is placed in the uncovered water tank 1 and the water storage baffle 5 as an evaporation source. When the number of stages of the distiller is changed, only the corresponding water storage baffle 5, the liquid storage tank 3 and the condensing plate 4 need to be detached or added. The height of the uncovered water tank 1 and the water storage baffle 5 is preferably within 5 cm.

As shown in fig. 6, the reservoir 3 may store substances such as seawater, sewage, nanofluids, or water-containing porous materials that can absorb solar energy and generate water vapor. The reservoir 3 is placed in the uncovered water tank 1 and the water storage baffle 5. When the reservoir 3 is located in the uncovered water tank 1, it is preferably in the form of a nanofluid or an aqueous porous material or the like having a high absorbance. When the liquid storage tank 3 is located in the water storage baffle 5, the liquid storage tank is preferably in the form of relatively transparent liquid substances such as seawater, sewage and the like, so that sunlight enters the liquid storage tank 3 located in the uncovered water tank 1 through the liquid storage tank 3 located in the water storage baffle 5 and is sufficiently absorbed. When the distiller is of a single-stage sub-structure, the liquid storage tank 3 in the water storage baffle 5 is used as condensate liquid for reducing the temperature of the condensation plate 4 and promoting the condensation of steam. When the distiller is of a multi-stage substructure, the liquid storage tank 3 in the water storage baffle 5 is used as a condensate and a stage steam source at the same time, and is used for reducing the temperature of the condensing plate 4 and recovering the latent heat of condensation from the condensing plate 4.

According to the solar distiller disclosed by the invention, the condensing plate is horizontally arranged, and the thickness of the water layer on the second layer and above layers of the device can be adjusted as required, so that the solar distiller can be conveniently suitable for different working conditions to enable the system to be in a state of higher efficiency all the time. Meanwhile, the thickness and the shape of each layer can be changed by a plurality of subsystems according to requirements, so that the system is suitable for different working conditions, such as different space limitations. Furthermore, the whole thickness of the device is small, and the polygonal structure of the device enables the device to have excellent stability and wind resistance when the device is flatly placed on the ground or the sea surface.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A solar distiller for collecting condensed water based on capillary action is characterized by comprising one or more vertically sequentially superposed solar distiller substructures, wherein each single solar distiller substructure comprises a bottom layer uncovered water tank (1), a water collecting tank (2), a condensing plate (4) and a water storage baffle (5); wherein the content of the first and second substances,

the bottom layer uncovered water tank (1) is a base of the single solar distiller substructure, a liquid storage tank (3) is arranged inside the bottom layer uncovered water tank (1), and nano fluid or a water-containing porous material is arranged in the liquid storage tank (3) and used for absorbing sunlight and converting solar energy into heat energy to evaporate liquid into water vapor;

the condensation plate (4) covers the uncovered water tank (1) and is not in contact with the liquid in the liquid storage tank (3), the condensation plate (4) comprises a condensation surface (401) and a dripping surface (402), the surfaces of the condensation surface (401) and the dripping surface (402) are both provided with capillary structures, the dripping surface (402) is in contact with the inner baffle inner wall (202) of the water collecting tank (2), the capillary force of the dripping surface (402) is larger than that of the condensation surface (401), in this way, the condensation surface (401) is used for rapidly condensing the water vapor from the liquid storage tank (3) and transporting the condensed water to the dripping surface (402) through the capillary action, and the dripping surface (402) rapidly absorbs the condensed water transported by the condensation surface (401) through the capillary action and collects the condensed water, so that the water vapor is prevented from directly collecting on the condensation surface (401); at the same time, the waste heat energy of the water vapor is transferred to the solar still subsystem of the previous layer through the condensation surface (401) to realize the multi-stage utilization of the energy, and

the water collecting tank (2) is arranged on the side surface of the uncovered water tank (1) or the water storage baffle (5) and is used for collecting condensed water from the dripping surface (402);

the water storage baffle (5) is hermetically connected with the condensing plate (4) below the water storage baffle, and the water storage baffle and the condensing plate form a water tank.

2. A solar still according to claim 1, wherein the capillary structure is a porous micro-or nano-wire applied to the surface of the condensation surface (401) by deposition, spin coating, spray coating, bar coating, weaving or pressure welding.

3. A solar still according to claim 1 wherein the wicking structure is a transparent metal organic framework material having a porous structure.

4. A solar still according to claim 2 wherein the micro or nano wires have a diameter of less than 100 microns; the pore diameter of the porous structure formed by the micron lines or the nano lines is less than 10 millimeters.

5. A solar still according to any one of claims 1 to 4 wherein the condensation surface (401) is horizontally placed on the uncovered water tank (1) or water storage barrier (5) and the dripping surface (402) is directly connected or bonded to the condensation surface (401) as a unit.

6. A solar still according to any one of claims 1 to 4 wherein said drip surface (402) is provided at the peripheral edge or at part of the edge of the bottom surface of said condensation surface (401); and the dripping surface (402) is of an inverted pyramid structure with the bottom folded downwards.

7. A solar still according to claim 6 wherein the droplet landing (402) is a triangular structure or a plurality of triangular structures arranged in a horizontal array with the base of the triangular structure abutting the bottom of the condensation surface (401) to facilitate the formation of droplets at the base of the droplet landing (402).

8. A solar still according to any of the claims 1-4 wherein the cross section of the uncovered water tank (1) and the water storage barrier (5) is rectangular, polygonal or circular and matches the shape of the condensation plate (4).

9. A solar still according to any of claims 1-4 wherein the height of the uncovered water tank (1) and water storage barrier (5) is less than or equal to 5 cm.

10. A solar still according to any of the claims 1-4 wherein the uncovered tank (1) is provided with a water inlet (101) on at least one side wall and the uncovered tank (1) is provided with a water outlet (102) on at least one side wall; a water inlet (502) is formed in at least one side wall of the water storage baffle (5), and a water outlet (501) is formed in at least one side wall of the water storage baffle (5).

11. A solar still according to claim 10, characterised in that the uncovered tank (1) has said water inlet (101) and outlet (102) on each side wall.

12. A solar still according to claim 10 wherein the water storage baffles (5) are provided with said water inlet (502) and outlet (501) on each side wall.

13. A solar still according to any of claims 1-4 wherein the reservoir (3) is a tank structure for holding seawater, sewage, nanofluids or porous materials containing water.