A light condensing direct heating spiral falling film evaporation type solar distillation device

Abstract

The application discloses a light-gathering direct-heating spiral falling-film evaporation type solar distillation device and method, and belongs to the technical field of solar energy utilization and water treatment. The main device comprises a light-gathering lens, a light guide device, a spiral blade and a cylindrical cavity. First, cold seawater forms a uniform liquid film through water-absorbing material, and the liquid film flows downwards along the spiral blade to the bottom of a distiller; sunlight is gathered by the light-gathering lens to a collimator, and the gathered sunlight irradiates the bottom of the distiller along the light guide device; the bottom light-absorbing coating absorbs the sunlight to convert it into heat energy to heat seawater to generate water vapor; the water vapor condenses on the back of the spiral blade to release latent heat to heat the liquid film on the blade to repeatedly utilize the latent heat to produce fresh water. The structure of the spiral blade overcomes the problem of low heat transfer efficiency caused by inconsistent heat transfer distance, and widens the area of the evaporation surface and the condensation surface; in combination with the light-gathering structure, the seawater can be directly heated, so that the system structure is more compact and simple, and the heat energy utilization efficiency, water production efficiency and solar energy utilization rate are improved.

Description

TECHNICAL FIELD

[0001] The application discloses a light-concentrating direct-heating spiral falling-film evaporation type solar distillation device and method, and belongs to the technical field of solar energy utilization and water treatment. BACKGROUND

[0002] The solar distiller is one of solar seawater desalination technologies. The solar distiller is characterized by small size, simple device, simple principle, and no need for complex operation and maintenance. The solar distiller is very useful in places where fuel and electricity are insufficient, or where it is difficult to install a complex seawater desalination device (such as a reverse osmosis device), such as poor and remote coastal areas, small islands, ships and outdoor emergency water treatment.

[0003] At present, the yield and efficiency of the solar distiller are low, which limits the practical application. Optimizing the heat and mass transfer process of the system, researching suitable materials and system design are important ways to make the solar distiller develop to a new stage and make greater contributions to the field of seawater desalination. In order to improve the efficiency of the solar distiller, there are works of using micro-nano particles or materials with micro-nano structure to improve the solar evaporation efficiency. However, the works mainly focus on material science, and lack of research in the field of heat transfer and mass transfer. This leads to a series of problems, such as the cost of the distiller is easy to be high, and the thermodynamic and heat transfer optimization of each process in the distiller is insufficient.

[0004] The spiral structure can greatly increase the heat exchange surface area in a limited space. Meanwhile, in the multi-spiral structure, the heat exchange distance between any two spiral leaf surfaces is consistent, which avoids the heat loss caused by the inconsistent heat exchange distance between the upper and lower levels, and improves the heat exchange capacity of the system. In addition, under the loading of the multi-stage spiral blade, the temperature in the distiller can change continuously with the change of height, which greatly improves the heat energy utilization efficiency and further improves the water production efficiency of the whole system.

[0005] From the perspective of thermodynamics, any seawater desalination system driven by heat energy has a higher performance coefficient when operating at a higher temperature. The application of the solar concentrating system can make the solar seawater desalination system transition from the low-moderate temperature stage to the moderate-high temperature stage. Compared with other concentrating methods, the light loss of the concentrating lens is smaller, and the concentrating ability is stronger. In addition, the concentrating lens is lighter, thinner and lower in cost than the ordinary lens. Combined with the Fresnel concentrating technology, the structure of the distiller can be more compact, the evaporation temperature of the distiller can be improved, and the water production efficiency of the system can be improved. SUMMARY

[0006] Therefore, the application provides a light-concentrating direct-heating spiral falling-film evaporation type solar distillation device and method, which couples the concentrating lens with the distiller to improve the efficiency of the distiller.

[0007] A kind of concentrated direct heating spiral falling film evaporation solar distillation device and method, main device includes: condensing lens, lens support frame, sunlight, rotatable fixed point, collimator, high reflectivity mirror surface, freshwater sandwich, heat preservation layer, water vapor, along edge, cylindrical metal wall, spiral blade, light outlet, support column, bottom seawater, 16-absorbing coating, concentrated brine outlet, freshwater collection tank, freshwater outlet, freshwater, water-absorbing material, switch, cold seawater inlet, water collecting tank, baffle, condensed seawater, spiral blade 2, spiral insert piece, CPC condenser, support, heat collector hot stream inlet, heat exchanger, solar collector, water pump, heat collector plate joint, heat collector hot stream outlet, heat collector support frame.

[0008] Connection relationship: cold seawater enters from the seawater inlet at the top of spiral blade, then passes through water collecting tank, after cold seawater fills water collecting tank, overflow to spiral blade, baffle is closely attached to the back of water collecting tank, along edge is equipped on the left and right edges of spiral blade, baffle and along edge can prevent cold seawater from flowing out of spiral blade range;Water-absorbing material is adhered on spiral blade, water-absorbing material can absorb cold seawater to form uniform liquid film on spiral blade;Freshwater collection tank is installed at the back of spiral blade at certain interval, freshwater in freshwater collection tank flows into freshwater sandwich in support cylindrical pipe, the bottom of freshwater sandwich is communicated with the lowest level freshwater collection tank, the lowest level freshwater collection tank is communicated with freshwater outlet, freshwater in freshwater sandwich flows out along freshwater outlet;Cold seawater flows into bottom seawater along spiral blade and is heated and evaporated together;Lens support frame supports condensing lens, one end of lens support frame is fixed at rotatable fixed point;The direction of condensing lens is adjusted by adjusting rotatable fixed point to realize real-time sun tracking;Collimator can make incident light as much as possible exit as parallel light, reduce light loss caused by multiple reflection in light guide;The outer layer of cylindrical support body is cylindrical metal wall, the inner of cylindrical metal wall is heat preservation layer, the inner of heat preservation layer is freshwater sandwich, the inner of freshwater sandwich is high reflectivity mirror surface;Selective light transmission glass is equipped at light outlet;The lower part of cylindrical support body is equipped with four support columns, four support columns do not enclose closed space;The periphery of peripheral cylinder is formed by cylindrical metal wall, light-absorbing coating is laid on the bottom and certain height periphery of cylindrical metal wall, heat preservation layer is wrapped outside cylindrical metal wall.

[0009] The technical scheme adopted by the present application is as follows: firstly, cold seawater enters from the seawater inlet at the top of the spiral blade, and then passes through the water collecting tank. After the cold seawater fills the water collecting tank, it overflows and flows to the spiral blade. The water-absorbing material adhered to the spiral blade absorbs the cold seawater to form a uniform liquid film. The uniform liquid film formed by the cold seawater flows downward along the spiral blade to the bottom of the seawater and heats and evaporates. The sunlight transmitted through the condenser is collected by the condenser. The condenser can make the incident light as much as possible to be parallel light, reducing the light loss caused by multiple reflections in the light guide. After the sunlight passes through the condenser, it is reflected in the high reflector channel and then emitted from the light outlet. The light outlet is also provided with light-transmitting glass with high transmittance to sunlight. After the sunlight is emitted from the light outlet, it irradiates the light-absorbing coating around the seawater through the bottom seawater. The light-absorbing coating converts the sunlight into heat energy to heat the bottom seawater. After the bottom seawater is heated, it evaporates upward. The water vapor rises and condenses into fresh water when it meets the back of the spiral blade. The fresh water condenses into water droplets at the bottom of the spiral blade and flows into the fresh water collecting tank. The fresh water in the fresh water collecting tank flows into the fresh water interlayer in the supporting cylindrical pipe. The bottom of the fresh water interlayer is connected with the lowest fresh water collecting tank and the fresh water outlet. The fresh water in the fresh water interlayer flows out through the fresh water outlet. At the same time, the latent heat released by the condensation of water vapor heats the uniform liquid film formed by the condensed seawater on the spiral blade, so that the internal seawater of the water-absorbing material evaporates. The water vapor meets the back of the upper blade and condenses into fresh water. The heating-condensing-heating process is repeated to produce fresh water. The concentrated brine after evaporation can be discharged through the concentrated brine outlet.

[0010] The present application has the following advantages:

[0011] (1) The structure of the multi-stage spiral blade makes the heat transfer distance of the evaporation surface and the condensation surface consistent, overcoming the problem of low heat transfer efficiency caused by inconsistent heat transfer distance. The seawater flows along the spiral surface in a falling film mode, and the water temperature can change continuously with the change of height, realizing continuous temperature difference driven distillation and improving the water production rate.

[0012] (2) The structure of the multi-stage spiral blade improves the space utilization in a certain volume, greatly expands the area of the evaporation surface and the condensation surface in the limited space, and improves the heat transfer rate.

[0013] (3) The upper and lower sides of the spiral surface are evaporation surface and condensation surface respectively. The spiral surface itself can form a multi-stage structure, which can recycle the condensation latent heat of seawater and improve the heat utilization efficiency.

[0014] (4) The integrated design of light collection, heating, evaporator and condenser makes the system structure more simple and compact, reduces the operation and maintenance cost, and also reduces the occupied area. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a front view of the spiral falling film solar distillation device of the present application

[0016] Figure 2 Sectional view of the spiral blade and water absorbing material of the present invention

[0017] Figure 3 Sectional view of the internal structure of the cylindrical support body of the present invention

[0018] Figure 4 Double spiral falling film solar distillation device of the present invention with lens condensing system

[0019] Figure 5 Spiral falling film solar distillation device of the present invention with CPC condensing system

[0020] Figure 6 Spiral falling film solar distillation device of the present invention with solar collector plate

[0021] Wherein, 1 - condensing lens; 2 - lens support frame; 3 - sunlight; 4 - rotatable fixed point; 5 - collimator; 6 - high reflectivity mirror; 7 - fresh water interlayer; 8 - heat preservation layer; 9 - water vapor; 10 - along the edge; 11 - cylindrical metal wall; 12 - spiral blade; 13 - light outlet; 14 - support column; 15 - bottom seawater; 16 - light absorbing coating; 17 - concentrated brine outlet; 18 - fresh water collection tank; 19 - fresh water outlet; 20 - fresh water; 21 - water absorbing material; 22 - switch; 23 - cold seawater inlet; 24 - water collection tank; 25 - baffle; 26 - condensed seawater; 27 - spiral blade 2; 28 - spiral insert; 29 - CPC condenser; 30 - support; 31 - collector hot stream inlet; 32 - heat exchanger; 33 - solar collector plate; 34 - water pump; 35 - collector plate joint; 36 - collector hot stream outlet; 37 - collector support frame. DETAILED DESCRIPTION

[0022] As shown in the accompanying drawings Figure 1 , Figure 2 and Figure 3As shown, the present application provides a light condensation direct heating spiral falling film evaporation type solar distillation device and method, the main device includes: condensing lens (1), lens support frame (2), rotatable fixed point (4), collimator (5), high reflectivity mirror (6), fresh water sandwich (7), heat preservation layer (8), along the edge (10), cylindrical metal wall (11), spiral blade (12), light outlet (13), support column (14), light absorbing coating (16), concentrated brine outlet (17), fresh water collection tank (18), fresh water outlet (19), water absorbing material (21), cold seawater inlet (23), water collecting tank (24), baffle (25). Wherein the top of the spiral blade (12) is provided with a water collecting tank (24) at the seawater inlet (23), the water collecting tank (24) is closely attached to the baffle (25) behind, the left and right edges of the spiral blade (12) are provided with the along edge (10); the water absorbing material (21) is adhered to the spiral blade (12), the water absorbing material (21) can absorb cold seawater to form a uniform liquid film on the spiral blade (12); the back of the spiral blade (12) is provided with a fresh water collection tank (24) at a certain interval, the fresh water (20) in the fresh water collection tank (18) flows into the fresh water sandwich (7) in the support cylindrical pipe, the bottom of the fresh water sandwich (7) is communicated with the lowest level fresh water collection tank (18), the lowest level fresh water collection tank (18) is communicated with the fresh water outlet (19), and the fresh water (20) in the fresh water sandwich (7) flows out along the fresh water outlet (19); the lens support frame (2) supports the condensing lens (1), one end of the lens support frame (2) is fixed at the rotatable fixed point (4); the direction of the condensing lens (1) is adjusted by adjusting the rotatable fixed point (4) to realize real-time sun tracking; the collimator can make the incident light as much as possible to be parallel light, and reduce the light loss caused by multiple reflections in the light guide; the outer layer of the cylindrical support body is the cylindrical metal wall (11), the inner of the cylindrical metal wall (11) is the heat preservation layer (8), the inner of the heat preservation layer (8) is the fresh water sandwich (7), and the inner of the fresh water sandwich (7) is the high reflectivity mirror (6); the light outlet (13) is provided with selective light transmission glass; the lower part of the cylindrical support body is provided with four support columns (14), and the four support columns (14) do not form a closed space; the periphery of the peripheral cylinder is composed of the cylindrical metal wall (11), the bottom of the cylindrical metal wall (11) and the periphery of a certain height are paved with the light absorbing coating (16), and the cylindrical metal wall (11) is wrapped with the heat preservation layer (8).

[0023] The working process is as follows: firstly, cold seawater enters from the seawater inlet (23) at the top of the spiral blade (12), and then passes through the water collecting tank (24). After the cold seawater fills the water collecting tank (24), it overflows and flows to the spiral blade (12). The water-absorbing material (21) adhered to the spiral blade (12) absorbs the cold seawater to form a uniform liquid film. The uniform liquid film formed by the cold seawater flows downward along the spiral blade (12) to the bottom seawater (15) and evaporates after being heated. The concentrated sunlight is collected by the condenser (5) through the light condensing lens (1). The condenser can make the incident light as much as possible to be parallel light, reducing the light loss caused by multiple reflections in the light guide. After the sunlight passes through the condenser (5), it is reflected in the high reflector (6) channel and then emitted from the light outlet (13). The light outlet (13) is also equipped with selective light transmission glass. The selective light transmission glass at the light outlet (13) allows the reflected light to be emitted but prevents sunlight outside the light outlet (13) from entering the reflector. After the sunlight is emitted from the light outlet (13), it irradiates the light-absorbing coating (16) around the seawater through the bottom seawater (15).

[0024] The light-absorbing coating (16) converts sunlight into heat energy to heat the bottom seawater (15). After being heated, the bottom seawater (15) evaporates upward. The water vapor (9) rises and condenses into fresh water (20) after encountering the back of the spiral blade (12). The fresh water (20) condenses into water droplets at the bottom of the spiral blade (12) and flows into the fresh water collecting tank (18). The fresh water (20) in the fresh water collecting tank (18) flows into the fresh water interlayer (7) in the supporting cylindrical tube. The bottom of the fresh water interlayer (7) is connected to the lowest level of the fresh water collecting tank (18) and the fresh water outlet (19). The fresh water (20) in the fresh water interlayer (7) flows out through the fresh water outlet (19). At the same time, the latent heat released by the condensation of water vapor (9) heats the uniform liquid film formed by the condensed seawater on the spiral blade (12), causing the internal seawater of the water-absorbing material (21) to evaporate. The water vapor (9) then encounters the back of the spiral blade (12) of the next level to condense into fresh water (20), repeating the heating-condensing-heating process to produce fresh water. The concentrated brine after evaporation can be discharged through the concentrated brine outlet (17).

[0025] As shown in one embodiment, Figure 4 If the radius of the spiral blade is large, it is more difficult for the water-absorbing material to absorb water and form a uniform liquid film. Therefore, multiple water baffles are inserted into the spiral blade to divide the multiple spiral blades into multiple small areas to make the liquid film on the spiral fan blade more uniform and convenient. Multiple spiral inserts (28) that follow the trend of the spiral blade are used to replace the multiple horizontal water baffles to achieve regional action. An additional spiral blade 2 (27) is added. Compared with a single spiral, the multi-spiral structure improves the space utilization rate and greatly increases the evaporation area of the heat flow and the condensation area of the water vapor.

[0026] As shown in one embodiment, Figure 5In one embodiment shown, replacing the lens condenser with a CPC condenser (29) makes the condensing structure simpler and easier to implement; the CPC condenser (29) uses a support (30) for weight-bearing, and the support (30) is connected to a rotatable fixed point (4) which can be rotated to adjust the condensing direction.

[0027] like Figure 6 In one embodiment shown, the method of removing the concentrator structure and using a solar collector to collect heat and then exchanging heat with the bottom seawater (15) to heat the seawater is another effective and feasible way to improve the heat production of the solar distiller. Figure 6 In this embodiment, the heat flow heated by the solar collector (33) and the heat flow between adjacent collectors are connected by the collector plate joint (35). When the solar collector (33) works to a certain extent and the heat flow in the vacuum tube reaches a certain temperature, the switch (17) is turned on and the heat flow flows into the heat exchanger (32). The water pump (34) makes the solar collector, the heat flow outlet (36) of the collector, the heat exchanger (32) and the heat flow inlet (31) of the collector form a closed loop to heat and evaporate the seawater.

[0028] Therefore, the description of the specific embodiments in this invention is not intended to limit the concept and scope of the invention. Any modifications and improvements made to the technical solution by those skilled in the art without departing from the technical solution of this invention will still fall within the protection scope of this invention.

Claims

1. A concentrating direct heating spiral falling film evaporation type solar distillation device, characterized in that, It comprises: lens condenser, light guide assembly, inner cylindrical support and outer cylindrical cavity; the lens condenser comprises condensing lens (1), lens support frame (2), rotatable fixed point (4); the light guide assembly comprises collimator (5), high reflectivity mirror (6), light outlet (13); the inner cylindrical support comprises freshwater interlayer (7), heat preservation layer (8), cylindrical metal wall (11), support column (14); the upper end of the high reflectivity mirror (6) is sealingly connected with the collimator (5), and the lower end is sealingly connected with the light outlet (13), so that a closed light guide assembly is formed; the freshwater interlayer (7) is a closed interlayer; the outer cylindrical cavity comprises heat preservation layer, cylindrical metal wall and light absorbing coating (16); the outer cylindrical cavity is an open container, and the heat preservation layer of the outer cylindrical cavity is closely attached to the cylindrical metal wall, and the light absorbing coating (16) is sprayed on the inner side bottom of the cylindrical metal wall of the outer cylindrical cavity; the lens condenser, the light guide assembly and the inner cylindrical support are integrally connected; It also comprises a spiral falling film evaporative distiller assembly, which comprises edge (10), spiral blade (12), freshwater collection tank (18), freshwater outlet (19), water absorbing material (21), cold seawater inlet (23), water collecting tank (24) and baffle (25); the cold seawater inlet (23) is connected with the water collecting tank (24), and the water collecting tank (24) and the baffle (25) are installed on the top of the spiral blade (12); the freshwater collection tank (18) is installed on the bottom of the spiral blade (12), and the freshwater collection tank (18) is connected with the freshwater outlet (19); the water absorbing material (21) is laid on the spiral blade (12); the spiral blade (12) is fixed between the inner and outer cylindrical metal walls; The working method of the condensing direct heating spiral falling film evaporative solar distillation device comprises that the light absorbing coating (16) can convert sunlight into heat energy to heat the bottom seawater (15); after being heated, the seawater (15) evaporates upward, the water vapor (9) rises and condenses into freshwater (20) after meeting the back of the spiral blade (12), and the released latent heat of phase change heats the uniform liquid film of the condensed seawater on the spiral blade (12), so that the seawater in the water absorbing material (21) evaporates, the water vapor (9) meets the back of the spiral blade (12) of the upper level again to condense and phase change into freshwater (20), so that the heating-condensing-heating process is repeatedly performed to produce freshwater, the latent heat is recycled multiple times, and the heat utilization efficiency is improved.

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