Heat pipe type seawater desalination device and seawater desalination method

Abstract

The present invention belongs to the field of seawater desalination technology, specifically to a heat pipe desalination device and a seawater desalination method. The heat pipe desalination device comprises a sealed pipe structure, connected to the outside world via an outlet or pipe provided at the bottom. A focusing assembly is mounted on the outside of the base via a support structure, and the desalination and collection processes are completed within the base. The heat pipe desalination device is divided from top to bottom into an evaporation section, a connection section, and a condensation section.

Description

Technical Field

[0001] The present invention belongs to the technical field of seawater desalination, and in particular relates to a heat pipe type seawater desalination device and a seawater desalination method. Background Art

[0002] The world faces a severe energy crisis and freshwater shortage. Desalination is a sustainable technology for obtaining freshwater from seawater or brackish water, and its development holds promise for resolving this crisis. Current desalination technologies, including thermal distillation, reverse osmosis membranes, and electrodialysis, are generally subject to high energy consumption and high pollution levels. Therefore, it is necessary to develop new, low-carbon, and green desalination technologies.

[0003] Interfacial photothermal evaporation technology is a near-zero energy consumption seawater desalination technology that has emerged in recent years. The principle of this technology is to use photothermal conversion materials to convert sunlight into heat energy for evaporating seawater, and set up condensation components to collect the steam generated by evaporation to obtain fresh water. This technology can be efficiently utilized in the thin water layer at the air-water interface through photothermal conversion, and has great application potential and prospects in the field of solar seawater desalination. However, this technology is currently limited by the energy density of the input sunlight. The low energy density of the input sunlight will lead to a low photothermal evaporation rate. In addition, the low rate of the steam-to-fresh water conversion process will further make the actual water production rate difficult to meet the application. Therefore, improving the energy input quality of seawater desalination equipment and optimizing the heat-to-mass conversion efficiency are the keys to achieving high-throughput seawater desalination.

[0004] Patent application number CN202010664522.7, titled "A Heat Pipe Capillary Driven Small-Scale Seawater Desalination System," discloses a device that increases desalination efficiency and yield by spraying unevaporated seawater through multiple cycles. The device is complex in structure and primarily utilizes heat collectors and electric heating plates to collect heat. This heat is then transferred via heat transfer pipes to a heat sink-type turbulent evaporator for seawater evaporation. Heat is easily lost during pipe transmission, and the device does not address the low energy density of the source light.

[0005] In summary, it is necessary to propose a new seawater desalination device to alleviate the problem of low photothermal evaporation efficiency caused by low light energy density in the existing technology. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a heat pipe seawater desalination device and a seawater desalination method, and the specific technical solutions are as follows.

[0007] A heat pipe desalination device, wherein the base of the heat pipe desalination device is a closed pipe structure, connected to the outside world through an outlet or pipe provided at the bottom. A focusing assembly is provided on the outside of the base via a support structure, and the desalination and collection process of seawater is completed within the base. The heat pipe desalination device is divided from top to bottom into an evaporation section, a connection section, and a condensation section.

[0008] The evaporation section includes a concentrating module and a seawater desalination module; the concentrating module includes at least two sets of angle-adjustable concentrating panels, which are connected to the base of the heat pipe desalination device via a bracket (the angle of the concentrating panels is flexibly adjustable); the seawater desalination module is sequentially provided with a double-layer vacuum heat collection tube, a water absorption and evaporation layer, and a water-proof and breathable membrane from the outside to the inside; the inner layer of the double-layer vacuum heat collection tube is coated with a light-absorbing material at one end close to the water absorption and evaporation layer.

[0009] The connecting section serves as a connecting component for connecting and sealing the evaporation section and the condensation section.

[0010] The condensation section is formed by nesting a double-layer pipe structure, and the nested pipe structure forms two inner and outer chambers as independent condensing water chambers and cooling water chambers. A pipe and an outlet are arranged at the bottom to communicate with the outside world.

[0011] Furthermore, the vacuum heat collecting tube is a double-layer vacuum glass tubular structure with a closed top (to reduce environmental heat dissipation); a light absorbing material is coated on one end of the inner glass side wall close to the water absorbing evaporation layer to receive the solar energy absorbed by the concentrating plate and convert it into heat energy.

[0012] Furthermore, the light absorbing material is a gradient aluminum-nitrogen composite coating; the coating thickness is 0.1-0.3 μm and the area is 0.10-1.0 m 2 .

[0013] Furthermore, the water absorption and evaporation layer is attached to the inner side of the vacuum heat collecting tube; the water absorption and evaporation layer has a thickness of 1-3 mm and an area of ​​0.1-1.0 m 2 porous carbon felt material.

[0014] Furthermore, the water-proof and breathable membrane is arranged on the inner side of the water absorption and evaporation layer facing the interior of the heat pipe type seawater desalination device base. The size of the water-proof and breathable membrane matches the water absorption and evaporation layer, and is used to isolate seawater and allow water vapor to pass through.

[0015] Furthermore, the material of the water-proof and breathable membrane is polytetrafluoroethylene; the material of the connecting section is polytetrafluoroethylene (which has good thermal stability and thermal insulation, and is easy to process).

[0016] Furthermore, in the double-layer pipe structure of the condensation section, the inner layer is a copper tube and the outer layer is an acrylic tube; the hollow structure sandwiched in the middle of the double-layer pipe structure forms a cooling water cavity, and a cooling water inlet and outlet are set at the bottom; the inner copper tube forms a condensation water cavity, which is used to load the fresh water produced by the evaporation section.

[0017] Furthermore, a fresh water outlet is provided at the bottom of the condensation water chamber; a pipeline for conveying seawater is connected to the middle of the double-layer pipeline structure, and the other end of the pipeline is connected to the water absorption and evaporation layer.

[0018] A method for desalinating seawater using the above-mentioned heat pipe desalination device comprises the following steps:

[0019] S01: placing the heat pipe seawater desalination device outdoors in a place with sufficient sunlight;

[0020] S02: Seawater is pumped into the heat pipe desalination device through the pipe at the bottom;

[0021] S03: Seawater enters the water absorption and evaporation layer of the heat pipe desalination device through a pipe. The porous carbon felt material of the water absorption and evaporation layer fully absorbs the seawater by its own capillary force and is always in a state of saturated absorption of seawater;

[0022] S04: The concentrating plate on the outside of the base of the heat pipe desalination device and the light absorbing material coated on the double-layer vacuum heat collecting tube inside the base cooperate to absorb and amplify solar energy, converting the solar energy into heat energy, causing the seawater adsorbed in the water absorption and evaporation layer in S03 to evaporate and generate water vapor, which then passes through the waterproof and breathable membrane and enters the interior of the base of the heat pipe desalination device;

[0023] S05: Cold water is further introduced into the cooling water chamber of the heat pipe desalination device. The water vapor generated in S04, driven by the temperature difference between the evaporation section and the condensation section, condenses into fresh water, which falls into the condensation water chamber of the heat pipe desalination device and is collected from the fresh water outlet. Generally, condensed fresh water is produced after about 10 minutes of pumping seawater.

[0024] Furthermore, the light absorption rate of the light absorbing material is 0.98; the thermal conductivity of the evaporation material is 0.09 to 0.13wm -1 k -1 .

[0025] Beneficial technical effects

[0026] 1) The present invention provides a simple and compact integrated desalination / condensation device. The device utilizes the effective coupling of photothermal desalination and heat pipe technology, effectively concentrates sunlight through a butterfly-shaped concentrator, and adopts a heat pipe structure to reduce heat dissipation, thereby achieving high-throughput desalination of seawater.

[0027] 2) In the heat pipe desalination device proposed in the present invention, the coordinated use of the focusing assembly and the vacuum collector tube effectively increases the input of solar energy flux density, that is, the density of the source solar energy is amplified, and the evaporation and desalination efficiency of seawater in the water absorption and evaporation layer is improved.

[0028] 3) The heat pipe seawater desalination device proposed in the present invention cleverly separates the fresh water production port from the light absorption port by using a waterproof and breathable membrane and a double-layer vacuum heat collecting tube. Therefore, the fresh water produced by the device will not adhere to the light absorption port and affect the efficiency of the working of this part of the component. Therefore, the light-to-heat conversion capacity of the device will not decrease after long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the embodiments or the description of the prior art. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the various elements or parts are not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without inventive work.

[0030] Summary of reference numerals:

[0031] Evaporation section 100, connecting section 200, condensation section 300, peristaltic pump 400, focusing module 110, first focusing plate 111, second focusing plate 112, bracket 113, seawater desalination module 120, vacuum heat collecting tube 130, light absorbing material 131, water absorbing evaporation layer 140, waterproof breathable membrane 150, outer tube 310, inner tube 311, cooling water chamber 320, cooling water inlet and outlet 321, condensation water chamber 330, fresh water outlet 331.

[0032] Figure 1 A schematic cross-sectional view of the overall structure of a heat pipe type solar thermal seawater desalination device provided in an embodiment of the present invention;

[0033] Figure 2 This is a real picture of the outdoor test of the prototype of the heat pipe solar thermal desalination device;

[0034] Figure 3 This is a physical picture of the heat pipe solar thermal desalination device;

[0035] Figure 4 Accumulate water production data for a heat pipe solar thermal seawater desalination device in one embodiment;

[0036] Figure 5 Hourly water production rate data of a heat pipe seawater desalination device in one embodiment;

[0037] Figure 6 Schematic diagram of a traditional interface evaporation device used as a control in one of the embodiments. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] As used herein, "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0041] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0042] As used in this specification, the term "about" typically means + / - 5% of the stated value, more typically + / - 4% of the stated value, more typically + / - 3% of the stated value, more typically + / - 2% of the stated value, even more typically + / - 1% of the stated value, and even more typically + / - 0.5% of the stated value.

[0043] In this specification, some embodiments may be disclosed in a format of being within a certain range. It should be understood that such description of "being within a certain range" is only for convenience and brevity and should not be interpreted as a rigid limitation on the disclosed range. Therefore, the description of a range should be considered to have specifically disclosed all possible sub-ranges and independent numerical values ​​within this range. For example, the range The description of should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within this range, for example, 1, 2, 3, 4, 5, and 6. The above rules apply regardless of the breadth of the range.

[0044] Example 1

[0045] This embodiment provides a structural example of a heat pipe seawater desalination device.

[0046] A heat pipe seawater desalination device has a base portion that is a closed pipe structure and is connected to the outside world through an outlet or pipe provided at the bottom. The device is divided from top to bottom into an evaporation section 100, a connection section 200, and a condensation section 300.

[0047] The evaporation section 100 includes a concentrating module 110 and a desalination module 120. The concentrating module 110 includes at least two sets of concentrating panels (a first concentrating panel 111 and a second concentrating panel 112), which are symmetrically connected to the base of the heat pipe desalination device via brackets 113. More than two sets of concentrating panels may be provided depending on actual needs. The desalination module 120 is equipped, from the outside to the inside, with vacuum heat collection tubes 130, a water absorption and evaporation layer 140, and a water-insulating and breathable membrane 150.

[0048] The evacuated heat collecting tube 130 is a double-layered vacuum glass tubular structure with a closed top. A light-absorbing material 131 is coated on the inner glass sidewall, near the water-absorbing and evaporating layer 140, to receive solar energy absorbed by the first and second concentrating plates 111, 112 and convert it into thermal energy. The light-absorbing material 131 in the double-layered glass structure of the evacuated heat collecting tube 130 concentrates solar energy. Furthermore, the double-layered glass reduces ambient heat dissipation, increasing the source's solar energy flux density and, consequently, the rate of conversion to water vapor.

[0049] The water absorption and evaporation layer 140 is arranged on the inner side of the vacuum heat collecting tube 130 and is close to the light absorption material 131 , so as to improve the heat energy conversion efficiency.

[0050] The water-proof and breathable membrane 150 is provided on the inner side of the water-absorbing and evaporating layer 140 and faces the inside of the device base. The size of the water-proof and breathable membrane 150 matches that of the water-absorbing and evaporating layer 140 and is used to isolate seawater and allow water vapor to pass through.

[0051] The connecting section 200 serves as a connecting component for connecting and sealing the evaporation section 100 and the condensation section 300 .

[0052] The bottom of the condensation section 300 is provided with a pipeline and an outlet communicating with the outside.

[0053] Among them, the condensation section 300 is mainly composed of a double-layer pipe structure (the outer layer pipe 310 is made of acrylic; the inner layer pipe 311 is made of copper pipe). The hollow structure sandwiched between the two layers of pipes forms a cooling water cavity 320, and a cooling water inlet and outlet 321 is set at the bottom; the inner layer pipe forms a condensation water cavity 330.

[0054] The condensate chamber 330 is used to store fresh water obtained through evaporation and purification in the desalination module. A fresh water outlet 331 is located at its bottom. A seawater pipeline is connected to the center of the double-layered pipe structure, and the other end of the pipeline is connected to the water absorption and evaporation layer 140. Optionally, a peristaltic pump 400 can be connected to the seawater inlet end of the pipeline.

[0055] As a preferred embodiment, the material used for the water absorption and evaporation layer 140 of this embodiment is a porous carbon felt material, and the optional material includes the SMZ5MM model produced by Beihai Carbon Company, which has a specific surface area of ​​400 to 1350 g m -2 , the carbon content is about 98%, and the thermal conductivity is 0.09~0.13wm -1 k -1 .

[0056] As a preference, the vacuum heat collecting tube 130 used in this embodiment may optionally include the model zk42000292 produced by Nozhi Company; the light absorbing material 131 may optionally be a gradient aluminum-nitrogen composite coating with a light absorption rate of 0.98.

[0057] Example 2

[0058] This embodiment provides a specific example of a heat pipe seawater desalination method.

[0059] The method for desalination of seawater is implemented based on the device of Example 1, and the specific steps are as follows:

[0060] S01: placing the heat pipe seawater desalination device outdoors in an unobstructed and sunny place;

[0061] S02: Seawater is pumped into the heat pipe desalination device through the pipe at the bottom;

[0062] S03: The seawater is pumped into the water absorption and evaporation layer 140 of the heat pipe desalination device through a peristaltic pump. The pumping rate of the seawater is controlled at 10-20 ml min -1 The porous carbon felt material in the water absorption and evaporation layer 140 fully absorbs the seawater by its own capillary force and is always in a state of saturated absorption of seawater;

[0063] S04: The angle of the concentrating plates is adjusted to ensure they face the sun. The concentrating plates 111 and 112 of the heat pipe desalination device and the light absorbing material 131 coated inside the double-layer evacuated heat collecting tubes 130 cooperate to absorb and amplify solar energy, efficiently converting it into heat energy. The seawater adsorbed in the porous carbon felt in S03 evaporates to produce water vapor, which then passes through the waterproof and breathable membrane 150 and enters the interior of the device base.

[0064] S05: Cold water is further introduced into the cooling water chamber 320 of the heat pipe desalination device (through the cooling water inlet and outlet 321). The water vapor generated in S04, driven by the temperature difference between the evaporation section 100 and the condensation section 300, condenses into fresh water and falls into the condensation water chamber 330 below. The water is then collected from the fresh water outlet 331, completing the desalination and collection process. Generally, condensed fresh water is produced after about 10 minutes of pumping in seawater.

[0065] In this embodiment, the coating thickness of the light absorbing material 131 is 0.1 μm and the coating area is 0.13 m 2 .

[0066] In this embodiment, the thickness of the water evaporation layer 140 is 2 mm and the area is 0.1 m 2 .

[0067] Experimental results

[0068] Table 1 Cumulative water production data

[0069] time <![CDATA[Cumulative water production rate / L m -2 > <![CDATA[Solar irradiance / W m -2 > 10:00 3.41 579.5 12:00 12.05 842.4 14:00 22.64 889.2 16:00 32.12 674.5 18:00 38.95 362.6

[0070] Table 2 Hourly water production rate data

[0071] time <![CDATA[Using condensed water / W m -2 > <![CDATA[Without condensed water / W m -2 > 10:00 1.94 3.41 12:00 2.68 4.52 14:00 2.84 5.57 16:00 2.12 4.31 18:00 1.41 3.12

[0072] Experimental conclusion: See the experimental diagram Figure 4 and Figure 5 The device and method of this embodiment are used to desalinate seawater outdoors in sunny weather with no obstructions. The freshwater output is 3.2 to 5.5 L m -2 h -1 .

[0073] Example 3

[0074] Conventional interface evaporation desalination technology is a process in which photothermal evaporation materials directly absorb sunlight, and through photothermal conversion, heat is generated to heat the seawater at the evaporation interface to produce water vapor. In addition, the fresh water produced by evaporation will adhere to the condensation cover and fall to the fresh water collection area below under the action of gravity. The more fresh water adheres to the condensation cover, the more it affects the absorption efficiency of sunlight. This technical process is as follows Figure 6 As shown. Due to the low solar energy flux density, the photothermal evaporation rate of evaporation materials is usually around 1.4 kg m -2 h -1 The actual freshwater production rate is also less than 1 L m -2 h -1In contrast, the heat pipe desalination technology proposed in this invention effectively improves the input of solar energy flux density through the use of concentrating and vacuum heat collecting tubes, further improves the evaporation rate of the evaporation material, and realizes efficient condensation of water vapor through the condensation component, thereby ultimately obtaining 3.2-5.5L m -2 h -1 freshwater production rate.

[0075] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A heat pipe seawater desalination device, characterized in that: The base of the heat pipe desalination device is a closed pipe structure, which is connected to the outside world through an outlet or pipe provided at the bottom. A focusing assembly is provided on the outside of the base through a support structure, and the desalination and collection process of seawater is completed in the base. The heat pipe desalination device is divided into an evaporation section, a connection section, and a condensation section from top to bottom. The evaporation section includes a concentrating module and a seawater desalination module; the concentrating module includes at least two sets of angle-adjustable concentrating panels connected to the base of the heat pipe desalination device via a bracket; the seawater desalination module is sequentially provided with a double-layer vacuum heat collecting tube, a water absorption and evaporation layer, and a water-insulating and breathable membrane from the outside to the inside; the inner layer of the double-layer vacuum heat collecting tube is coated with a light-absorbing material at one end near the water absorption and evaporation layer; The connecting section serves as a connecting component for connecting and sealing the evaporation section and the condensation section; The condensation section is formed by nesting a double-layer pipe structure, and the nested pipe structure forms two inner and outer chambers as independent condensing water chambers and cooling water chambers. A pipe and an outlet are arranged at the bottom to communicate with the outside world.

2. The heat pipe seawater desalination device according to claim 1, characterized in that: The vacuum heat collecting tube is a double-layer vacuum glass tubular structure with a closed top. A light absorbing material is coated on one end of the inner glass side wall close to the water evaporation layer to receive the solar energy absorbed by the concentrating plate and convert it into heat energy.

3. The heat pipe seawater desalination device according to claim 2, characterized in that: The light absorbing material is a gradient aluminum-nitrogen composite coating; the coating thickness is 0.1-0.3 μm and the area is 0.10-1.0 m 2 .

4. The heat pipe seawater desalination device according to claim 1, characterized in that: The water absorption and evaporation layer is attached to the inner side of the vacuum heat collecting tube; the water absorption and evaporation layer has a thickness of 1-3 mm and an area of ​​0.1-1.0 m 2 porous carbon felt material.

5. The heat pipe seawater desalination device according to claim 1, wherein: The water-proof and breathable membrane is arranged on the inner side of the water-absorbing and evaporating layer facing the interior of the heat pipe type seawater desalination device base. The size of the water-proof and breathable membrane matches the water-absorbing and evaporating layer and is used to isolate seawater and allow water vapor to pass through.

6. The heat pipe seawater desalination device according to claim 1, characterized in that: The material of the water-proof and breathable membrane is polytetrafluoroethylene; the material of the connecting section is polytetrafluoroethylene.

7. The heat pipe seawater desalination device according to claim 1, wherein: In the double-layer pipe structure of the condensing section, the hollow structure sandwiched between the double-layer pipe structure forms a cooling water cavity, and a cooling water inlet and outlet are set at the bottom of the cavity; the inner pipe forms a condensing water cavity for loading the fresh water produced by the evaporating section.

8. The heat pipe seawater desalination device according to claim 7, characterized in that: A fresh water outlet is provided at the bottom of the condensation water chamber; a pipeline for conveying seawater is connected to the middle of the double-layer pipeline structure, and the other end of the pipeline is connected to the water absorption and evaporation layer.

9. A method for desalinating seawater using the heat pipe seawater desalination device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S01: placing the heat pipe seawater desalination device outdoors in a place with sufficient sunlight; S02: Seawater is pumped into the heat pipe desalination device through the pipe at the bottom; S03: Seawater enters the water absorption and evaporation layer of the heat pipe desalination device through a pipe. The porous carbon felt material of the water absorption and evaporation layer fully absorbs the seawater by its own capillary force and is always in a state of saturated absorption of seawater; S04: The concentrating plate on the outside of the base of the heat pipe desalination device and the light absorbing material coated on the double-layer vacuum heat collecting tube inside the base cooperate to absorb and amplify solar energy, converting the solar energy into heat energy, causing the seawater adsorbed in the water absorption and evaporation layer in S03 to evaporate and generate water vapor, which then passes through the waterproof and breathable membrane and enters the interior of the base of the heat pipe desalination device; S05: Cold water is introduced into the cooling water chamber of the heat pipe desalination device. The water vapor generated in S04 is converted into condensed fresh water under the influence of the temperature difference between the evaporation section and the condensation section, and falls into the condensation water chamber of the heat pipe desalination device and is collected from the fresh water outlet.

10. The method according to claim 9, wherein The light absorption rate of the light absorbing material is 0.98; the thermal conductivity of the evaporation material is 0.09 to 0.13wm -1 k -1 .

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