Anti-salt solar seawater desalination system based on reverse distillation of low heat capacity water layer

Abstract

The present invention discloses a salt-resistant solar desalination system based on reverse distillation of a low-heat-capacity water layer, which belongs to the field of solar desalination. The present invention is composed of a transparent cover plate, a light-absorbing plate, a hydrophobic breathable membrane, a support net, a condensation plate, a side plate, a water supply bottle, a water supply pipe, etc. When the system is working, the light-absorbing plate absorbs sunlight and converts it into heat energy to heat the seawater in the water layer. The steam generated by the downward evaporation of seawater passes through the hydrophobic breathable membrane and the support net in turn and is finally condensed on the condensation plate. While the seawater evaporates, the seawater in the high-position water supply bottle is automatically replenished into the water layer, continuously supplying seawater to the water layer. The seawater inlet is located at the lowest position by a tilting device, which promotes the uniform distribution of seawater salinity in the water layer and reduces the risk of salt formation; the seawater outlet is set and a valve is installed to control the discharge of seawater before saturation to achieve sustainable distillation; the latent heat of steam condensation is recovered by setting a multi-stage stacked structure to improve the energy utilization efficiency of the system.

Description

Technical Field

[0001] The invention relates to a salt-resistant solar seawater desalination system based on reverse distillation of a low-heat-capacity water layer, belonging to the technical field of solar thermal utilization and seawater desalination. Background Art

[0002] Freshwater, an essential resource in human life, is gaining increasing attention, especially in coastal areas. Desalination technology is a crucial means of obtaining freshwater resources, and using solar energy to drive desalination contributes to energy conservation, emission reduction, and sustainable development. Traditional passive solar desalination systems utilize a distiller-type structure. The high heat capacity of the large amount of seawater pre-placed in the distiller inhibits distillation performance. Sunlight exposure and seawater evaporation occur on the same side of the ocean surface, and the light-incoming surface is also the condensation surface. Condensed droplets weaken the sunlight entering the device. Furthermore, this distillation method is not conducive to enhanced condensation and recovery of latent heat of condensation.

[0003] In recent years, solar desalination systems based on hydrophilic core reverse distillation have been proposed. This allows sunlight exposure and seawater evaporation to occur on different sides of the ocean surface, decoupling the two processes. This prevents condensation droplets from interfering with incoming light and greatly facilitates enhanced condensation and recovery of latent heat. However, this hydrophilic core-based reverse distillation method triggers salt crystallization at the evaporation interface, limiting its sustainability. Summary of the Invention

[0004] In view of this, the present invention provides a salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer, which can avoid salt crystallization through the flow inside the water layer while achieving low heat capacity reverse distillation.

[0005] A salt-resistant solar desalination system based on reverse distillation of a low-heat-capacity water layer comprises a transparent cover, a light-absorbing plate, a hydrophobic breathable membrane, a support net, a condensation plate, side plates, a water supply bottle, and a water supply pipe. The transparent cover is a transparent plate; the light-absorbing plate is a flat plate with a solar-selective absorption coating on the top and good thermal conductivity; the hydrophobic breathable membrane blocks the permeation of water but allows the permeation of gas; the support net is a porous plate with a certain degree of hardness; the condensation plate is a flat plate with good thermal conductivity; and the side walls are sealed and heat-insulating plates.

[0006] The side wall supports a transparent cover plate and a light-absorbing plate, and the three form an enclosed air domain. The side wall supports a light-absorbing plate and a hydrophobic breathable membrane, and the three form an enclosed water layer. The distance between the light-absorbing plate and the hydrophobic breathable membrane is set to 1mm-20mm to achieve low heat capacity distillation of the water layer. The support net is close to the hydrophobic breathable membrane and is located below it. The side wall, hydrophobic breathable membrane, support net, and condensation plate form an enclosed air domain. A small hole is opened at one end of the side wall of the water area, and a water supply pipe is used to connect the small hole and the water supply bottle. The water level in the water supply bottle is higher than the water level of the water layer. A small hole is opened in the part of the side plate located between the support net and the condensation plate, which serves as an outlet for fresh water droplets.

[0007] Working principle: Sunlight passes through the transparent cover and is absorbed by the light-absorbing plate, heating the seawater below the light-absorbing plate. After being heated, the seawater generates steam downwards, which passes through the hydrophobic breathable membrane and the support net in turn and finally reaches the condensation plate, condensing to form fresh water. The moment the seawater is evaporated, the seawater in the water supply bottle at a higher position will be replenished into the seawater below the light-absorbing plate through the water supply pipe under the action of the siphon, thereby realizing the water replenishment function. The device is tilted 10°-60° so that the entrance of the water layer is at the lowest position of the entire water area. This method allows the high-salinity seawater in the water layer away from the inlet end to flow back to the inlet end, thereby making the salinity of the seawater inside the entire water layer evenly distributed, maximizing the salt solubility of all seawater in the water layer.

[0008] Furthermore, a small hole is drilled in the side panel at the opposite end of the water layer from the inlet, serving as a seawater outlet. This is connected to a pipe and valve. The device is tilted 5-60 degrees so that the outlet is at the lowest point of the water layer. This ensures that the density and salinity of the seawater at the outlet are the highest in the entire water layer. The valve controls the drainage flow rate, ensuring that the seawater at the outlet is discharged before reaching saturation.

[0009] Furthermore, in order to increase the water production per unit light-incoming area, a multi-level stacked structure is arranged under the condensation plate, and the structural layout between the light-absorbing plate and the condensation plate is repeated to recover the latent heat of water vapor condensation and improve energy utilization efficiency.

[0010] Beneficial effects

[0011] 1. The salt-resistant solar seawater desalination system based on reverse distillation of a low-heat-capacity water layer of the present invention can realize low-heat-capacity, salt-resistant solar seawater desalination, has a lower seawater heat capacity than traditional distiller and a better distillation efficiency than traditional distiller, and improves the salt crystallization resistance of the reverse distiller using a hydrophilic core.

[0012] 2. The salt removal method of the present invention can meet the requirements of sustainable distillation of high-concentration seawater or brine without salt crystallization.

[0013] 3. The multi-stage distillation structure can recover the latent heat of condensation between stages and achieve ultra-efficient water production per unit light-incoming area. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer according to the present invention.

[0015] Figure 2 The figure is a schematic diagram of an embodiment of the salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer according to the present invention in the seawater discharge mode.

[0016] Figure 3 The diagram is a schematic diagram of an embodiment of a salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer in a multi-stage distillation configuration according to the present invention.

[0017] Among them, 1-transparent cover; 2-light-absorbing plate; 3-side plate; 4-condensation droplets; 5-condensation plate; 6-fresh water outlet; 7-support net; 8-hydrophobic breathable membrane; 9-seawater inlet; 10-water supply bottle; 11-seawater; 12-water supply pipe; 13-water layer; 14-sunlight; 15-seawater outlet; 16-drain pipe; 17-valve. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0019] As attached Figure 1 As shown, the present invention provides a salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer, comprising a transparent cover plate 1, a light-absorbing plate 2, a hydrophobic breathable membrane 8, a support net 7, a condensation plate 5, a side plate 3, a water supply bottle 10, and a water supply pipe 12; wherein, the transparent cover plate 1 is a transparent plate; the light-absorbing plate 2 is a flat plate with a solar selective absorption coating on the top and good thermal conductivity; the hydrophobic breathable membrane 8 blocks the permeation of water but allows the permeation of gas; the support net 7 is a hard porous plate; the condensation plate 5 is a flat plate with good thermal conductivity; and the side plate 3 is a sealed heat-insulating plate.

[0020] The side panel 3 supports the transparent cover plate 1 and the light-absorbing plate 2, and the three of them form a closed air domain. The side panel 3 supports the light-absorbing plate 2 and the hydrophobic breathable membrane 8, and the three of them form a closed water layer 13. The distance between the light-absorbing plate 2 and the hydrophobic breathable membrane 8 is set to 1mm-20mm to achieve low heat capacity distillation of the water layer 13. The support net 7 is close to the hydrophobic breathable membrane 8 and is located below it. The side panel 3, the hydrophobic breathable membrane 8, the support net 7, and the condensation plate 5 form a closed air domain. A small hole is opened at one end of the side panel 3 of the water layer 13 as a seawater inlet 9, and a water supply pipe 12 is used to connect the seawater inlet 9 and the water supply bottle 10. The water level in the water supply bottle 10 is higher than the water level of the water layer 13. A small hole is opened in the part of the side panel 3 located between the support net 7 and the condensation plate 5, which serves as a fresh water outlet 6 for the condensed droplets.

[0021] Working principle: When the system is working, sunlight 14 passes through the transparent cover plate 1 and is then absorbed by the light-absorbing plate 2, heating the seawater in the water layer 13 below the light-absorbing plate. After being heated, the seawater generates steam downwards, and passes through the hydrophobic breathable membrane 8 and the support mesh 7 in sequence to finally reach the condensation plate 5, condensing to form condensation droplets 4. The moment the seawater is evaporated, the seawater 11 in the water supply bottle 10 at a higher position will be replenished into the water layer 13 below the light-absorbing plate 2 through the water supply pipe 12 under the action of siphon, thereby realizing the water replenishment function. The device is tilted 10°-60° so that the seawater inlet 9 of the water layer 13 is at the lowest position of the entire water layer. This approach allows the high-salinity saltwater in the water layer 13 away from the seawater inlet 9 to flow back to the seawater inlet 9, thereby making the salinity of the seawater inside the entire water layer 13 evenly distributed, maximizing the salt solubility of all seawater in the water layer 13.

[0022] exist Figure 2 In the illustrated embodiment, a small hole is opened in the side panel 3 at the end of the water layer 13 opposite the seawater inlet 9, serving as a seawater outlet 15. This hole is connected to a drain pipe 16 and a valve 17. The device is tilted 5°-60° so that the seawater outlet 15 is at the lowest point of the entire water layer 13. This ensures that the seawater density and salinity at the seawater outlet 15 are the highest in the entire water layer 13. The drainage flow rate is controlled by valve 17, ensuring that the seawater at the seawater outlet 15 is discharged before reaching saturation.

[0023] exist Figure 3 In one embodiment shown, in order to increase the water production per unit light-incoming area, a multi-level stacked structure is arranged below the condensation plate 5, and the structural layout between the light-absorbing plate 2 and the condensation plate 5 is repeated to recover the latent heat of water vapor condensation and improve energy utilization efficiency.

[0024] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer, characterized in that: The invention comprises a transparent cover plate (1), a light absorbing plate (2), a hydrophobic breathable membrane (8), a support net (7), a condensation plate (5), a side plate (3), a water supply bottle (10), and a water supply pipe (12); wherein the transparent cover plate (1) is a transparent plate; the light absorbing plate (2) is a flat plate with a solar selective absorption coating on the top and good thermal conductivity; the hydrophobic breathable membrane (8) blocks the permeation of water but allows the permeation of gas; the support net (7) is a hard porous plate; the condensation plate (5) is a flat plate with good thermal conductivity; and the side plate (3) is a sealed heat-insulating plate. The side plate (3) supports the transparent cover plate (1) and the light absorbing plate (2), and the three of them enclose a closed air domain; the side plate (3) supports the light absorbing plate (2) and the hydrophobic breathable membrane (8), and the three of them enclose a closed water layer (13); the spacing between the light absorbing plate (2) and the hydrophobic breathable membrane (8) is set to 1mm-20mm to achieve a low heat capacity distillation function; the support net (7) is closely attached to the hydrophobic breathable membrane (8) and is located below it; the side plate (3), the hydrophobic breathable membrane (8), the support net (7), and the condensation plate (5) enclose a closed air domain; the side plate (3) of the water layer (13) A small hole is opened at one end as a seawater inlet (9), and a water supply pipe (12) is used to connect the seawater inlet (9) and the water supply bottle (10); the water level in the water supply bottle (10) is higher than the water level of the water layer (13); a small hole is opened in the portion of the side plate (3) located between the support net (7) and the condensation plate (5) as a fresh water outlet (6) for condensed liquid droplets (4); the whole composed of the transparent cover plate (1), the light absorbing plate (2), the hydrophobic breathable membrane (8), the support net (7), the condensation plate (5), and the side plate (3) is tilted clockwise by 10°-60° with the seawater inlet (9) as the center to achieve salt resistance.

2. The salt-resistant solar seawater desalination system based on reverse distillation of a low heat capacity water layer according to claim 1, characterized in that: A multi-level stacked structure is arranged below the condensation plate (5), and the structural layout between the light absorbing plate (2) and the condensation plate (5) is repeated to achieve a heat recovery function.

Images