A solar heat collecting type seawater desalination device

Abstract

The present application relates to solar seawater desalination technology field, it provides a kind of solar heat collection type seawater desalination device, it includes lower water inlet pipe and upper steam pipe, several closed heat collection pipes are uniformly connected between water inlet pipe and steam pipe;Single heat collection pipe is equipped with the heat storage suite for storing solar heat energy, heat storage suite includes the sleeve of outside and the inner tube of inside, sleeve and inner tube are closed and filled with phase change material;The cavity between sleeve and heat collection pipe is vacuumized;The lower end of inner tube is communicated with water inlet pipe, and ultrasonic atomizer is arranged at the communicating portion;The upper end of inner tube is communicated with steam pipe, and hydrophobic ceramic membrane is arranged at the communicating portion;Inner tube is equipped with topological structure, and topological structure is accelerated to the seawater in inner tube by several groups of rib, which is oriented to middle part and is in the shape of bionic branch, to heat transfer.The present application uses topological structure to greatly increase heating contact area and evenly distribute radial heat, so that heat energy, water vapor transmission path is shorter, and resistance is smaller.

Description

Technical Field

[0001] This invention relates to the field of solar-powered seawater desalination technology, and more particularly to a solar-powered seawater desalination device. Background Technology

[0002] Solar membrane distillation (SMD) technology combines solar thermal utilization with membrane distillation to drive seawater desalination using renewable, low-grade heat sources. A typical SMD system consists of two parts: a solar collector unit and a membrane distillation module. The solar collector unit can be a flat-plate collector, a vacuum tube collector, or a concentrating collector. Its function is to absorb solar radiation and convert it into heat to heat the circulating working fluid. The heated working fluid transfers heat to the seawater to be treated through a heat exchanger, raising the temperature of the hot-side seawater to a predetermined temperature before it enters the membrane distillation module for separation. The cold side can be maintained at a low temperature using circulating cooling water, air cooling, or natural cooling to ensure the transmembrane vapor pressure difference. Existing literature reports various configurations of SMD systems, such as direct contact, air-gap, scavenging, and vacuum membrane distillation integrated with solar collectors. These systems are particularly suitable for coastal and remote areas with abundant solar resources but scarce freshwater resources, and have the potential for distributed and green applications.

[0003] Ultrasonic atomization technology is a technique that uses ultrasonic vibration energy to break down liquid media into tiny droplets. Existing ultrasonic atomization technology has the following shortcomings in seawater desalination or brine treatment applications: during atomization, salt is atomized along with water, making in-situ separation impossible; while condensing and collecting the atomized droplets can yield fresh water, the equipment is bulky and has low thermal efficiency. Furthermore, the atomization volume of conventional ultrasonic atomization systems is significantly affected by liquid surface tension, viscosity, and salinity; atomization efficiency decreases significantly at high salinity, limiting its feasibility for direct application in seawater desalination.

[0004] Although solar membrane distillation technology has shown promising application prospects in seawater desalination, several technical bottlenecks still exist in practical engineering applications, hindering its performance and economic viability. Objectively speaking, existing solutions still have room for improvement in terms of mass transfer mechanism, membrane stability, and flow channel structure, requiring collaborative innovation at the system level.

[0005] (1) The contradiction between temperature polarization and mass transfer efficiency has not been fundamentally resolved.

[0006] In traditional membrane distillation, water vapor absorbs a significant amount of latent heat when it vaporizes at the membrane surface, resulting in a feed liquid temperature near the membrane surface that is significantly lower than the mainstream liquid temperature, forming a "temperature polarized" boundary layer. This phenomenon weakens the effective transmembrane vapor pressure differential, causing the actual flux to be far lower than the theoretical value. To compensate for the flux loss, conventional approaches are to increase the hot-side temperature or increase the circulation flow rate. The former increases the solar collector area, while the latter increases the energy consumption of the circulation pump, making it difficult to optimize overall energy efficiency. The reason for this is that existing membrane modules mostly use simple flow channel structures such as parallel flat plates or hollow fiber bundles, lacking effective control over the coupling effect of the thermal boundary layer and concentration boundary layer, and thus limiting heat transfer enhancement methods. This indicates that reconstructing the vaporization mechanism at the mass transfer mechanism level, rather than simply patching up the existing framework, is a feasible solution to improve energy efficiency.

[0007] (2) Membrane fouling and hydrophobic stability failure have long constrained long-term operation.

[0008] The long-term stable operation of hydrophobic membranes is one of the core challenges in the engineering of membrane distillation technology. During seawater concentration, inorganic salts, colloids, and microorganisms easily deposit on the membrane surface and within the pores, causing flux decline. More importantly, the "vapor-permeable, liquid-impermeable" function of hydrophobic membranes relies on their surface hydrophobicity. Once covered by salt crystals or organic matter, or when the membrane material ages during thermal cycling, "membrane wetting" can occur, leading to a sharp decline in the quality of the produced water. Existing solutions mainly rely on periodic chemical cleaning or membrane module replacement, but chemical cleaning accelerates membrane aging, and frequent replacements increase operating costs. Therefore, how to effectively suppress fouling and wetting without damaging the membrane structure remains a crucial aspect that has not yet been adequately addressed in the current technological system.

[0009] (3) The flow channel structure design of the membrane module leads to uneven heat and mass transfer distribution.

[0010] Existing membrane distillation modules often employ simple geometric configurations such as rectangular or parallel grooves for their hot-side flow channels, which easily lead to flow dead zones and short-circuit flow phenomena. This results in highly uneven velocity distribution across the membrane surface, causing localized overheating or undercooling and reducing membrane area utilization efficiency. The non-uniformity of the temperature field further exacerbates the localized effects of temperature polarization, causing some membrane surfaces to wet prematurely due to excessive flux, while others remain idle due to insufficient mass transfer driving force. Furthermore, the cold-end design also suffers from similar limitations: traditional metal condenser plates (such as copper plates) have planar contact with the cooling medium, limiting the heat transfer area; grooved channels are often simple parallel grooves, leading to uneven condensate distribution under surface tension and gravity, easily forming a liquid film that increases thermal resistance and prevents the cold end from effectively matching the vaporization flux of the hot end. This indicates that there is still significant room for optimization in the existing flow channel structure regarding the coordination of fluid distribution and heat and mass transfer.

[0011] (4) The functional use of ultrasonic technology is limited to auxiliary cleaning and is not deeply integrated with the mass transfer process.

[0012] In recent years, researchers have attempted to introduce ultrasonic atomization technology into membrane separation processes, utilizing the microjets generated by ultrasonic cavitation to suppress contaminant deposition on membrane surfaces. However, in current applications, the function of ultrasound is mostly limited to the "cleaning" level. The ultrasonic transducer acts directly on the membrane module, and while its intense cavitation effect can remove contaminants, it can also easily cause impact damage to the hydrophobic membrane surface, accelerating hydrophilicity failure and mechanical damage. In other words, the "atomization" function of ultrasound and the "vaporization mass transfer" process of membrane distillation have not yet formed a mechanistic coupling; ultrasound is only used as an external auxiliary means, not a core component of the mass transfer process. How to transform ultrasonic atomization from "passive cleaning" to "actively enhanced mass transfer" while avoiding damage to the membrane structure is a promising direction for breakthroughs in the current technological system.

[0013] In summary, existing solar membrane distillation technology still faces challenges in addressing high-salinity seawater desalination, including the contradictions between mass transfer efficiency and temperature polarization, membrane fouling and hydrophobic stability, uneven heat and mass distribution within the flow channel, and insufficient utilization of ultrasonic capabilities. These problems are interconnected and mutually restrictive, making fundamental breakthroughs difficult to achieve through improvements in a single dimension. Summary of the Invention

[0014] In order to overcome or alleviate one or more of the above technical problems, the present invention aims to provide a solar thermal seawater desalination device. This device has undergone mass transfer mechanism reconstruction, membrane material adaptation and flow channel structure biomimicry, which can not only enhance vaporization efficiency, but also effectively suppress pollution and wetting, while realizing the efficient utilization of solar energy.

[0015] This invention provides the following technical solution:

[0016] A solar-powered seawater desalination device includes a lower inlet pipe (7) and an upper steam pipe (10). Several sealed heat collection tubes (1) are uniformly connected between the inlet pipe (7) and the steam pipe (10). Each heat collection tube (1) is provided with a heat storage kit (6) for storing solar thermal energy. The heat storage kit (6) includes an outer heat transfer sleeve and an inner heat transfer tube. The space between the sleeve and the inner tube is sealed and filled with phase change material. The cavity between the sleeve and the heat collection tube (1) is vacuum treated. The lower end of the inner tube is connected to the inlet pipe (7), and an ultrasonic atomizer (3) is provided at the connection. The upper end of the inner tube is connected to the steam pipe (10), and a hydrophobic ceramic membrane (4) is provided at the connection. The inner tube is provided with a topology structure (2). The topology structure (2) accelerates heat transfer to the seawater in the inner tube through several sets of ribs facing the center and with a biomimetic tree branch-shaped cross section.

[0017] Preferably, the topology includes at least four sets of ribs.

[0018] Preferably, the thickness of a single rib is 1 to 3 mm.

[0019] Preferably, the rib extends inward from the inner wall of the inner tube, and the extension range is 60% to 90% of the inner diameter of the inner tube.

[0020] Preferably, the ribs are made of copper and are polished.

[0021] Preferably, both the sleeve and the inner tube are made of copper.

[0022] Preferably, the outer wall of the inner tube is provided with an ultrasonic oscillator (5).

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) To address the technical problems of "temperature polarization" caused by the latent heat of vaporization of water vapor and low mass transfer efficiency in traditional membrane distillation, this invention designs a solar-powered seawater desalination device. Technically, by enhancing the heat exchanger design through a topological structure, the highly selective separation process of membrane distillation, the thermally driven process of solar distillation, and the microscale efficient mass transfer process generated by ultrasonic atomization are organically connected. The effect is that the topological structure significantly increases the heating contact area and uniformly distributes radial heat, resulting in shorter and less resistant heat and material (water vapor) transfer paths, effectively weakening the temperature polarization boundary layer, thereby significantly improving the overall heat exchange efficiency and transmembrane vapor pressure difference.

[0025] (2) In view of the problem that conventional ultrasonic atomization systems in the background technology suffer from a significant decrease in atomization efficiency under high salinity and are prone to scaling on the membrane surface and pipes, the technical solution adopted in this application is to introduce ultrasonic oscillation technology. The effect is that, by utilizing its cavitation effect and shear force, it continuously destroys and inhibits the adhesion and growth of salt crystals on the membrane surface and inside the pipes during system operation, changing "periodic treatment" to "real-time prevention". Even in high salinity environments, it can maintain a high atomization volume, extend the life of core components and maintenance cycle, and ensure the long-term stability of water production.

[0026] (3) In view of the problem in the prior art that salt is atomized along with water during the atomization process and cannot be separated in situ, the technical solution adopted in this application is to combine ultrasonic atomization technology with a hydrophobic ceramic membrane. The effect is that the ultrasonic atomizer greatly increases the specific surface area of ​​water, creating conditions for evaporation; at the same time, by utilizing the separation characteristics of the hydrophobic ceramic membrane to accurately trap liquid water and salt ions and allow only water vapor to pass through, salt is successfully blocked, realizing in-situ and efficient freshwater production, avoiding the problems of large size and low thermal efficiency of traditional equipment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a solar-powered seawater desalination device provided in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the internal structure of the heat collection tube provided in an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of a biomimetic branch-shaped topology provided in an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the ultrasonic atomizer structure provided in an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram of the structure of an ultrasonic oscillator provided in an embodiment of the present invention.

[0032] Figure 6 This is a schematic cross-sectional view of a vacuum tube provided in an embodiment of the present invention.

[0033] In the picture:

[0034] 1. Heat collection tube; 2. Topology; 3. Ultrasonic atomizer; 4. Hydrophobic ceramic membrane; 5. Ultrasonic oscillator; 6. Heat storage kit; 7. Water inlet pipe; 8. Water inlet; 9. Steam outlet; 10. Steam pipe. Detailed Implementation

[0035] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0036] Example 1

[0037] 1. Solar-powered seawater desalination plant and its installation process

[0038] like Figure 1 As shown, the solar thermal seawater desalination device consists of multiple heat collection tubes 1, a topology structure 2, an ultrasonic atomizer 3, a hydrophobic ceramic membrane 4, and an auxiliary system. Several heat collection tubes 1 are connected between the parallel water inlet pipe and the steam pipe. The heat collection tube 1 has an ultrasonic atomizer 3 at the lower water inlet end and a hydrophobic ceramic membrane at the steam end. An ultrasonic oscillator 5 is installed on the upper part of the copper tube inside the heat collection tube 1.

[0039] (1) Heat collection tube

[0040] like Figure 2As shown, the seawater desalination device is a solar vacuum tube type. The collector tube 1 is made of heat-resistant glass, and a brass heat storage kit 6 is coaxially installed inside it. The copper tube is inserted into a copper sleeve, with the upper end of the sleeve extending beyond the copper tube and the lower end flush with it. Both ends are sealed with circular steel caps. After welding, a 5 mm threaded hole is made in the upper steel cap, and after injecting phase change material, it is sealed with screws and fitted with a silicone gasket to prevent leakage. The sleeve is placed inside the collector tube 1, and a vacuum is created between the inner wall of the collector tube 1 and the outer wall of the sleeve. The lower part of the copper tube is connected to the water inlet pipe 7, and the upper part is connected to the steam pipe 10.

[0041] After absorbing solar energy, the collector tube 1 heats the phase change material and copper tubes within the thermal storage kit. The heat is then rapidly conducted to the water inside the copper tubes of the collector tube 1 via the topology structure 2. The topology structure 2 is arranged on the inner wall of the copper tubes in the thermal storage kit. Its branched layout significantly increases the heating contact area, improving heat exchange efficiency compared to traditional straight-plate fins. This structure also ensures a more uniform radial heat distribution in the collector tubes, preventing uneven water vaporization caused by localized overheating. The manifold is a cylindrical double-layer aluminum alloy structure. The inner cavity is open at one end and closed at the other, with six equally spaced threaded holes at the bottom for copper tube connections. The open end is welded to the flange end face using tungsten inert gas welding. The outer cavity is open at both ends and coaxially mounted to the flange end face with the inner cavity. Both ends are also welded using tungsten inert gas welding. The inner wall of the outer cavity is threaded, with six circular holes slightly larger than the outer diameter of the vacuum tube, each fitted with a silicone gasket to achieve a sealed connection between the vacuum tube and the manifold.

[0042] (2) Topology

[0043] Topology 2 is a biomimetic tree-branch topology, which mimics the branching of trees, leaf vein networks, or biological cyclic systems in nature through multi-level fractal topologies. Its core design idea is to achieve efficient transport and distribution of matter or energy through hierarchical branching channels, aiming to minimize transport resistance while maximizing contact area, thereby enhancing heat and mass transfer processes. A typical structure features a main channel that branches into multiple sub-channels, with the diameter and length of each channel typically following the scaling laws of fractal geometry, resulting in uniform distribution of fluid or heat within the branch network and minimal pressure drop. This type of structure has been applied in microchannel radiators, fuel cell flow fields, microreactors, and distributed piping networks.

[0044] like Figure 3As shown, this device employs a biomimetic branching topology 2, with an overall "trident-shaped" radially symmetrical distribution. Four groups of fins are evenly spaced along the central axis of the copper tube, with each group extending into the inner cavity of the heat collection tube 1, achieving radial full-coverage heat transfer. Topology 2 is made of brass with high thermal conductivity, and the thickness of a single fin is set to 1–3 mm, which can be adjusted according to the inner diameter of the copper tube, the strength of the topology, and the processing precision. The overall dimensions of topology 2 are adapted to the inner cavity of the copper tube, with the fins extending from the inner wall of the copper tube towards the center, and their extension length being 60%–90% of the inner diameter of the copper tube, ensuring that the inner fins are tightly fitted to the inner wall of the copper tube without any contact gaps.

[0045] like Figure 6 As shown, the innermost components are a sleeve and a copper tube, with the copper tube containing seawater. Precision stamping is used to form the brass topological ribs, ensuring the curvature of the bottom of the branched structure matches the inner wall curvature of the copper tube, preventing gaps after assembly. The rib surfaces are polished to reduce fluid flow resistance and improve the smooth flow of atomized water mist. TIG welding is used to fix the outer ribs of the topological structure to the inner wall of the collector tube, while the inner ribs are welded to the copper sleeve of the thermal storage kit. Non-destructive testing is performed at the weld joints to ensure a weld strength ≥200 MPa, preventing the risk of detachment during high-temperature operation. The assembled thermal storage kit is placed inside the vacuum collector tube, and the position of the topological structure is adjusted to ensure the distance between its end and the inner side of the hydrophobic ceramic membrane is controlled at 0.5-1 mm, which does not affect the membrane module's separation function while maximizing heat transfer efficiency.

[0046] The topology 2 provided in this embodiment is adapted to the gas-liquid two-phase interface; the tree-shaped flow channel and the hydrophobic film structure are designed in a coordinated manner to reduce the concentration polarization and temperature polarization effects at the same time.

[0047] (3) Ultrasonic atomizer

[0048] like Figure 1 As shown, the inlet of the water inlet pipe at the bottom of the device is connected to the lower end of each heat collector tube 1. The seawater to be treated is distributed into the lower end of each heat collector tube through the inlet at the bottom of the device. Based on the preheating provided by the heat collector tube 1 and the heat storage kit 6, the ultrasonic atomizer 3 (such as...) installed at the lower end of the heat collector tube 1... Figure 4 (As shown) First, it plays a role by breaking up liquid seawater into micron-sized water mist through high-frequency vibration, greatly increasing the specific surface area of ​​the gas-liquid two-phase contact and creating conditions for efficient evaporation; at the same time, the ultrasonic oscillator 5 installed at the upper end of the outer wall of the inner copper tube of the collector tube 1 (as shown) Figure 5As shown, a continuous acoustic field is generated, forming a synergistic structure of "lower atomization and upper oscillation". The upper ultrasonic oscillator 5, on the one hand, disperses the upward-moving water mist secondary through acoustic flow effect and micro-jet, effectively avoiding the aggregation of droplets during the ascent process, so that the water mist always maintains a uniform and stable gas-liquid two-phase flow state. On the other hand, the cavitation effect and mechanical vibration generated by the ultrasonic oscillator 5 in the heat collection tube 1 play a continuous descaling role on the tube wall and heat exchange surface. The high-frequency micro-shock waves generated by ultrasonic oscillation can destroy the salt scale crystal structure that is forming, making it difficult for crystals to nucleate and grow on the wall surface. At the same time, it can cause fatigue cracks in the already attached scale layer and gradually peel off, thereby effectively preventing the scaling problem caused by salt concentration due to water evaporation, and ensuring the heat transfer efficiency and stability of the heat collection tube in long-term operation. The water mist, after being treated by atomization and oscillation, is transported upward to the hydrophobic ceramic membrane in a highly dispersed uniform flow pattern. The selective permeability of the membrane is used to achieve gas-liquid separation. Water vapor is collected as fresh water after passing through the membrane pores, while the retained concentrated brine is returned or discharged. A complete and optimized path was constructed within the collector tube, from liquid phase disruption and uniform transport to anti-fouling maintenance.

[0049] (4) Hydrophobic ceramic membrane

[0050] like Figure 6 As shown, a hydrophobic ceramic membrane 4 is installed between the copper tube at the upper end of the collector tube 1 and the steam pipe. The membrane has good hydrophobic and air-permeable properties. The steam outlet of the steam pipe located at the top of the copper tube is connected to the subsequent condensation system. In the lower part of the collector tube 1, the water absorbs heat energy and its temperature rises. When it reaches a certain temperature, the liquid water undergoes a phase change, producing high-temperature water mist and saturated water vapor, forming a vapor-liquid mixture. Driven by thermal pressure, this mixture flows upward and enters the area covered by the hydrophobic ceramic membrane 4 on the upper part of the collector tube 1. This hydrophobic ceramic membrane 4 has selective permeability: water vapor molecules, because their dynamic diameter is much smaller than the membrane pores, pass through the membrane pores under the drive of the vapor pressure difference on both sides of the membrane and reach the steam collection area on the other side of the membrane; while the size of liquid water droplets is much larger than the membrane pores, and due to the repulsive effect of the surface tension of the hydrophobic ceramic membrane 4, they cannot wet the membrane pores and are physically blocked on the collector tube side. At the same time, non-volatile salts, heavy metal ions, colloidal and solid impurities dissolved in the raw water are also efficiently intercepted by the membrane layer because they cannot migrate with the water vapor. Water vapor passing through the hydrophobic ceramic membrane 4 enters the steam outlet at the top of the device. Since this outlet is connected to the subsequent condensation system, a low steam partial pressure is maintained in the steam outlet area. Driven by the pressure difference, the water vapor continuously flows towards the condensation system, releasing latent heat and liquefying into high-purity fresh water. The trapped liquid water, concentrated salts, and impurities flow back along the inner wall of the collector tube to the lower heating zone, forming a circulating concentration process. This allows for recycling or periodic discharge, thereby achieving efficient separation of water and pollutants.

[0051] (5) Auxiliary system

[0052] The auxiliary system, including water inlet pipe, steam pipe, water inlet, steam outlet and condensation system, is used for inputting water to be treated, exporting fresh water steam and condensing it into liquid.

[0053] The desalination method of the solar thermal seawater desalination device provided in this embodiment is as follows:

[0054] An ultrasonic atomizer 3 is installed at the lower end of the collector tube 1, and a hydrophobic ceramic membrane 4 is installed at the upper end; the water inlet is connected to the water source to be treated, and the steam outlet is connected to the condenser coil. During sunshine, the collector tube 1 absorbs solar energy to heat the storage unit. After the water to be treated enters, it is atomized, separated, and condensed to obtain fresh water; during non-sunlight conditions, the phase change material releases heat to maintain the short-term operation of the device.

[0055] After absorbing solar energy, the collector tube 1 heats the phase change material and copper tube within the thermal storage kit. The heat is then rapidly conducted to the water within the copper tube through the topology 2 inside the collector tube 1. The branched layout of the topology 2 significantly increases the thermal contact area, improving heat exchange efficiency compared to traditional straight-plate fins. Simultaneously, the symmetrical distribution of the structure ensures more uniform radial heat distribution within the collector tube, preventing uneven water vaporization caused by localized overheating. The water to be treated is then broken into micron-sized water mist by the ultrasonic atomizer 3, and the upper ultrasonic oscillator 5 enhances the water mist flow, forming a high-temperature, highly dispersed gas-liquid two-phase flow. As the water mist flows upward, it comes into contact with the surface of the topology 2. The high-temperature surface of the topology 2 further preheats the water mist, shortening the time for the water mist to vaporize into a gaseous state and reducing the energy consumption of the ultrasonic oscillator 5. When the high-temperature water mist comes into contact with the hydrophobic ceramic membrane 4, the water vapor passes through the membrane layer and enters the steam outlet, where it is condensed to obtain fresh water. The retained concentrated water and impurities flow back to the heat collector tube 1. The residual heat of the topology 2 continues to maintain the temperature of the water mist, ensuring the kinetic energy of the water vapor molecules and increasing the rate at which the water vapor passes through the hydrophobic ceramic membrane 4. The fin gaps of the topology 2 provide a stable flow channel for the water vapor, optimize the water mist flow field, reduce the risk of condensation and blockage on the membrane surface, and extend the service life of the membrane module.

[0056] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A solar-powered seawater desalination device, characterized in that: It includes a lower water inlet pipe (7) and an upper steam pipe (10), and several sealed heat collection tubes (1) are uniformly connected between the water inlet pipe (7) and the steam pipe (10); each heat collection tube (1) is provided with a heat storage kit (6) for storing solar thermal energy, the heat storage kit (6) includes an outer heat transfer sleeve and an inner heat transfer tube, the sleeve and the inner tube are sealed and filled with phase change material; the cavity between the sleeve and the heat collection tube (1) is vacuum treated; the lower end of the inner tube is connected to the water inlet pipe (7), and an ultrasonic atomizer (3) is provided at the connection; the upper end of the inner tube is connected to the steam pipe (10), and a hydrophobic ceramic membrane (4) is provided at the connection; the inner tube is provided with a topology (2), the topology (2) accelerates heat transfer to the seawater in the inner tube through several sets of ribs facing the middle and with a biomimetic tree branch-shaped cross section.

2. The solar thermal seawater desalination device according to claim 1, characterized in that: The topology (2) includes at least 4 sets of ribs.

3. The solar thermal seawater desalination device according to claim 2, characterized in that: The thickness of a single rib is 1 to 3 mm.

4. The solar thermal seawater desalination device according to claim 3, characterized in that: The rib extends inward from the inner wall of the inner tube, with an extension range of 60% to 90% of the inner diameter of the inner tube.

5. The solar thermal seawater desalination device according to claim 4, characterized in that: The ribs are made of copper and are polished.

6. The solar thermal seawater desalination device according to claim 1, characterized in that: Both the sleeve and the inner tube are made of copper.

7. The solar thermal seawater desalination device according to any one of claims 1 to 6, characterized in that: An ultrasonic oscillator (5) is provided on the outer wall of the inner tube.

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