A nano-bubble liquid low-pressure preparation device and a photovoltaic cleaning system

Abstract

This application discloses a nanobubble liquid preparation device and a photovoltaic cleaning system. The preparation device includes an inlet pipe, a Venturi jet injector, a packed tower, a hydrocyclone, a collisioner, and an outlet pipe, connected sequentially by pipelines in the direction of the cleaning liquid flow. The Venturi jet injector is connected to the inlet pipe, the packed tower, and the gas delivery pipe. The packed tower is connected to the Venturi jet injector and the hydrocyclone. The hydrocyclone is connected to the packed tower and the collisioner. The collisioner is connected to the hydrocyclone and the outlet pipe. The beneficial effects of this application are: multi-stage energy input is achieved through step-by-step energy superposition, compensating for insufficient inlet pressure, stable preparation of nanobubble liquid under low-pressure environment, and the ability to briefly reach high-pressure conditions, promoting gas supersaturation and nanobubble nucleation, forming a dynamic pressure gradient within the device, which is beneficial for step-by-step energy superposition; the gas is repeatedly broken and refined, and the synergistic effect jointly prepares the nanobubble liquid, achieving step-by-step energy superposition and significantly reducing energy consumption.

Description

Technical Field

[0001] This utility model belongs to the field of gas-liquid two-phase mixing technology, and relates to a low-pressure preparation device for nanobubble liquid and a photovoltaic cleaning tank, especially a low-pressure preparation device for nanobubble liquid and a photovoltaic cleaning system that can be produced under low pressure in the photovoltaic cleaning industry. Background Technology

[0002] Tiny bubbles in liquids are classified according to their diameter into macrobubbles, microbubbles, submicron bubbles, or nanobubbles. Bubbles with a diameter in the range of 10-100 micrometers are called microbubbles, those in the range of 1-10 micrometers are submicron bubbles, and those in the range of 10-1000 nanometers are nanobubbles. Due to their large specific surface area, long residence time, high interfacial potential, ability to generate free radicals, and enhanced mass transfer, nanobubbles have excellent application prospects in many fields, such as wastewater treatment, plant cultivation, new material preparation, photovoltaic cleaning, and mineral flotation.

[0003] Due to the advantages of nanobubble liquid, its application in the photovoltaic cleaning industry has significant research value. In existing related technologies, nanobubble water is generally prepared using a pressure dissolution method. The traditional pressure dissolution method applies high pressure (5-10 MPa) in a closed container, utilizing the principle that increased pressure significantly enhances the solubility of gas in the cleaning solution to prepare stable nanobubble water. Under this high-pressure environment, gas solubility increases by 3-5 times, and bubble diameters are concentrated in the range of 50-200 nm. Especially at 10 MPa, nanobubbles smaller than 100 nm can be stably obtained. In contrast, bubble diameters prepared using the dissolved gas release method under normal or low-pressure environments are concentrated in the range of 1-50 μm (mainly micrometer-scale), with only a small amount reaching below 200 nm. At 0.6 MPa pressure, the peak bubble size is 40 μm, and nanobubbles account for less than 10%. Even with optimized shearing processes (such as high-speed vortexing), bubbles of 200-500 nm can be briefly generated, but their stability is poor (lifespan <1 minute). Therefore, when manufacturing nanobubble water, metal pumps that can provide high pressure are typically selected to provide the power. However, photovoltaic cleaning commonly uses alkaline cleaning agents, acidic cleaning agents, oxidants, composite cleaning solutions, surfactants, and other chemicals. Some of these chemicals are corrosive, making them unsuitable for transport using metal pumps. Magnetic pumps are required, but their pressure is relatively low, typically 0.1~1.6 MPa (with some models reaching 2.5 MPa or 4.0 MPa). This pressure is insufficient to meet the inlet pressure requirements of traditional nanobubble preparation methods, meaning that traditional pressurized dissolution methods cannot be used to prepare nanobubble water with the required size and stable performance. Therefore, traditional pressurized dissolution methods for preparing nanobubble water cannot be directly applied to the photovoltaic cleaning industry. Patent CN109985877A discloses a photovoltaic power station cleaning technology application, method, and device based on micro / nanobubble water. However, in practical applications, this application requires adding krypton gas to degassed water to 6 atmospheres and maintaining this pressure for 30 minutes. This high pressure requirement and long time consumption result in low production efficiency of the nanobubble generating equipment.

[0004] Therefore, there is an urgent need for a low-pressure preparation method and apparatus for high-density nanobubble liquid that can be directly applied to the photovoltaic cleaning industry, stably prepares high-density nanobubble water under low-pressure conditions, requires a small amount of cleaning solution, has a good cleaning effect, low energy consumption, and high production efficiency. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, this application provides a low-pressure preparation device and photovoltaic cleaning system for nanobubble liquid that can be directly applied to the photovoltaic cleaning industry, can stably prepare high-concentration nanobubble water under low-pressure conditions, has a small amount of cleaning stock solution, good cleaning effect, low energy consumption, and high production efficiency.

[0006] To solve the above problems, the technical solution adopted in this application is: This application provides a low-pressure preparation device for nanobubble liquid, comprising an inlet pipe, a Venturi ejector, a packed tower, a hydrocyclone, and an outlet pipe connected sequentially in the direction of liquid medium flow, wherein: The inlet pipe is configured to transport liquid media. The Venturi jet nozzle has its inlet, outlet, and air inlet connected to the inlet pipe, the packed tower, and the compressed air source, respectively, and is configured to form a primary gas-liquid mixture flow through gas-liquid mixing. A packed tower, which is filled with packing material, has its inlet and outlet connected to the jet generator and cyclone generator, respectively, and is configured to perform secondary shearing and collision on the primary gas-liquid mixture to form a secondary gas-liquid mixture. The hydrocyclone has its tangential inlet and outlet connected to the packed tower and the collisioner, respectively. The hydrocyclone is equipped with a redisper unit and is configured to perform gas-liquid separation on the two-stage gas-liquid mixture. After separation, the bubbles are refined and mixed with the liquid medium to form a three-stage gas-liquid mixture. The collider, whose inlet and outlet are connected to the hydrocyclone and outlet pipe respectively, is configured to cavitate and ultimately break up the three-stage gas-liquid mixture to form nanobubble liquid. The liquid outlet pipe is configured to output nanobubble liquid.

[0007] As a preferred embodiment of this application, the low-pressure preparation device for nanobubble liquid further includes a control unit, the control unit comprising: An exhaust control assembly includes an exhaust pipe connected to a packed tower and a pneumatic valve and a first throttle valve disposed on the exhaust pipe. The pneumatic valve and the first throttle valve are electrically connected to a controller and are used to regulate the gas flow rate in the exhaust pipe. An intake control assembly includes an intake control valve disposed on a gas delivery pipe, the intake control valve being electrically connected to a controller for regulating the gas flow rate within the gas delivery pipe; and The controller is electrically connected to the liquid inlet control component, the air inlet control component, and the exhaust control component, and is used to control the operation of the low-pressure nanobubble liquid preparation device.

[0008] As a preferred embodiment of this application, the low-pressure preparation device for nanobubble liquid further includes a control unit, the control unit comprising: The liquid inlet control assembly includes a liquid inlet control valve and a first flow meter disposed on the liquid inlet pipe. The liquid inlet control valve and the first flow meter are electrically connected to the controller and are used to regulate the flow rate and velocity of the liquid medium in the liquid inlet pipe. The air intake control assembly includes an air intake control valve and a second flow meter installed on the air supply pipe. The air intake control valve and the first flow meter are electrically connected to the controller and are used to regulate the gas flow rate and velocity in the air supply pipe. The liquid discharge control component includes a liquid discharge control valve and a third flow meter mounted on a liquid discharge pipe. The liquid discharge control valve and the third flow meter are electrically connected to a controller and are used to regulate the output flow rate and velocity of the nanobubble liquid within the liquid discharge pipe. The controller is electrically connected to the liquid inlet control component, the air inlet control component, and the liquid outlet control component, and is used to control the operation of the low-pressure nanobubble liquid preparation device.

[0009] As a preferred embodiment of this application, the Venturi jet ejector comprises an inlet jet section, a throat, and an outlet diffuser section connected in sequence, wherein: The liquid inlet jet section is conical, with its small diameter end connected to the first end of the throat tube and its large diameter end connected to the liquid inlet pipe, and is used to inject liquid medium into the throat tube. The throat tube is cylindrical in shape and has an air inlet on its side wall. The air inlet is connected to the air source through an air supply pipe and is used to inject the gas drawn in under negative pressure at the throat tube into the liquid medium flowing through the throat tube. The liquid outlet diffusion section is conical, with its small diameter end connected to the second end of the throat tube and its large diameter end connected to the packed tower. It is used to transport the primary gas-liquid mixture containing micron-sized bubbles to the packed tower.

[0010] As a preferred embodiment of this application, the Reynolds number Re ≥ 10000 is used to form high Reynolds number turbulence in the negative pressure zone of the Venturi jet.

[0011] As a preferred embodiment of this application, the packed tower includes a tower body, the top of which is provided with a gas phase outlet, an exhaust port, and a feed port. The gas phase outlet is configured to discharge the treated gas phase medium, the exhaust port is connected to the atmosphere, and the feed port is connected to the liquid outlet end of a Venturi jet via a first pipe. The bottom of the tower body is provided with a discharge port and a gas phase inlet. The discharge port is connected to the tangential inlet of a hydrocyclone via a second pipe, and the gas phase inlet forms a gas phase medium circulation channel with the gas phase outlet via a circulation pipeline.

[0012] As a preferred embodiment of this application, a distributor is provided inside the tower body.

[0013] As a preferred embodiment of this application, the tower body is filled with a porous material, which is a Raschig ring, a Pall ring, or a wire mesh. A Pall ring is preferred.

[0014] As a preferred embodiment of this application, the exhaust port of the packed tower is connected to an exhaust pipe, and the outlet of the exhaust pipe is equipped with a pneumatic valve and a first throttle valve to achieve slow exhaust.

[0015] As a preferred embodiment of this application, the gas pipeline is further equipped with a second throttle valve, a gas-opening valve, and a pressure recording controller to monitor and stabilize the pipeline pressure in real time.

[0016] As a preferred embodiment of this application, the hydrocyclone includes a cyclone separation unit and a redisperation unit. The cyclone separation unit comprises an axially connected cylindrical separation chamber and a conical separation chamber that gradually narrows from the bottom of the cylindrical body and communicates with the inner cavity of the cylindrical body. The sidewall of the cylindrical separation chamber has a tangential inlet, and the bottom of the conical separation chamber has an underflow outlet. The redisperation unit includes a variable-diameter flow channel structure. The fluid channel is a variable-diameter channel, with its inlet end sealed to the underflow outlet via a flange connection, and its outlet end connected to the collider inlet via a quick connector. The variable-diameter flow channel contains at least two remixing chambers, with adjacent remixing chambers transitionally connected by a straight pipe section of equal diameter. The secondary gas-liquid mixture enters the cyclone separation unit of the hydrocyclone through the tangential inlet, generating a high-speed rotating flow and forming a centrifugal force field. The liquid and gas stratify in the hydrocyclone, with the gas accumulating towards the central axis due to its lower density. The fluid velocity gradient inside the hydrocyclone is extremely large (especially in the conical separation chamber), forming a strong shear force field, which tears the gas into tiny bubbles under the action of shear force. The turbulent vortex in the swirling flow further breaks the bubbles down to the nanoscale (typically <1 μm). After flowing out from the underflow port of the swirling separation unit, the bubbles are sent to the redispersion unit. Due to the multiple changes in the diameter of the fluid channel in the redispersion unit, the pressure changes multiple times, which triggers local cavitation, generates bubble nuclei, and promotes the formation of nanobubbles. Finally, a three-stage gas-liquid mixture containing transitional nanobubbles is formed and sent into the collider from the outlet end of the redispersion unit.

[0017] As a preferred embodiment of this application, the ratio of the minimum diameter to the maximum diameter of the fluid channel is greater than 1 / 4.

[0018] As a preferred embodiment of this application, the collider includes a housing and a collision structure. The housing has a collision cavity inside and an inlet and an outlet connected to the collision cavity on the housing. The collision structure is a collision plate or a perforated plate disposed inside the housing.

[0019] As a preferred embodiment of this application, there are at least two liquid inlets, the axes of which all pass through the center of the collision cavity to form an intersecting structure, and the liquid outlets are symmetrically distributed on the sidewalls of the shell.

[0020] As a preferred embodiment of this application, the collision structure is a collision plate, and an annular medium channel is formed between the outer edge or inner edge of the collision plate and the inner wall of the shell, with the channel width being 1 / 10 to 1 / 5 of the diameter of the collision cavity.

[0021] Alternatively, the collision structure can be an orifice plate with micropores. The micropores on the orifice plate have a diameter of 50-200 nm and a porosity of ≥60%, and are arranged radially or in a matrix. When the collision structure is an orifice plate, the liquid forms a jet through the micropores of the orifice plate and converges and collides at the center of the cavity to generate a vortex. After the three-stage gas-liquid mixture is fed into the collisioner, it impacts the collision structure. The sudden drop in local pressure triggers cavitation, generating a transient high-pressure shock wave (>100 MPa), which breaks the bubbles into nanoscale particles. The microjet (velocity >100 m / s) generated when the bubbles collapse tears apart adjacent bubbles, further breaking them into nanoscale particles.

[0022] As a preferred embodiment of this application, the outlet end of the liquid outlet pipe is equipped with a nozzle for spraying nanobubble water onto the surface of the photovoltaic product to be cleaned, thereby removing and cleaning dust or contaminants from the surface. In use, a controllable gas and liquid medium are mixed in an ejector to obtain a primary gas-liquid mixture. This primary gas-liquid mixture then undergoes secondary shearing and collision in a packed tower to obtain a secondary gas-liquid mixture. This mixture is then fed into a hydrocyclone for gas-liquid separation and refinement, resulting in a tertiary gas-liquid mixture. Finally, it is sent to a collisioner for cavitation and final crushing to obtain nanobubble liquid. The nanobubble liquid is then sprayed onto the surface of the photovoltaic product to be cleaned using the nozzle, thereby removing and cleaning dust or contaminants from the surface.

[0023] As a preferred embodiment of this application, the low-pressure preparation device for nanobubble liquid further includes a reflux pipe and a reflux control valve disposed on the reflux pipe. One end of the reflux pipe is connected to the outlet pipe, and the other end of the reflux pipe is connected to the inlet pipe, for returning substandard nanobubble liquid to the Venturi jet injector; the reflux control valve is electrically connected to the controller.

[0024] This application also provides an application of a low-pressure nanobubble liquid preparation device in photovoltaic cleaning.

[0025] This application also provides a photovoltaic cleaning system, including: A liquid storage tank is used to store liquid media. The delivery pipe is connected to the liquid storage tank and the magnetic pump respectively, and is used to deliver the liquid medium in the liquid storage tank to the magnetic pump. A magnetic pump, connected to both the delivery pipe and the low-pressure preparation device for nanobubble liquid, is used to pressurize the liquid medium output from the storage tank and deliver it to the low-pressure preparation device for nanobubble liquid; and A low-pressure preparation device for nanobubble liquid, connected to a magnetic pump and a gas source, is used to form nanobubble liquid; and The gas storage tank is connected to the low-pressure preparation device for nanobubble liquid via a gas supply pipe, and is used to supply gas into the low-pressure preparation device for nanobubble liquid.

[0026] As a preferred embodiment of this application, the liquid storage tank is made of corrosion-resistant material and is used to store chemicals used in photovoltaic cleaning.

[0027] This invention also provides a low-pressure preparation method for high-density nanobubble liquid, comprising the following steps: Step 1, Primary jet breakup: The gas and liquid media are mixed through a Venturi jet injector at a volume ratio of 0.01~0.2:1. Through the jet negative pressure effect and turbulent shearing action, a primary gas-liquid mixture is formed. Step 2, Turbulent Refining: The primary gas-liquid mixture is fed into a packed tower filled with packing material. Under turbulent conditions with a Reynolds number Re≥4000, the bubbles are broken up a second time to obtain a secondary gas-liquid mixture. Step 3, Cyclone Recombination: The secondary gas-liquid mixture is fed into a hydrocyclone, where the bubbles are broken and redispersed in the rotating flow field to obtain a tertiary gas-liquid mixture. Step 4, cavitation treatment: The three-stage gas-liquid mixture is fed into the collider for cavitation and final breakup to obtain nanobubble liquid.

[0028] As a preferred embodiment of this application, the gas in step 1 is one or a combination of two or more of nitrogen, oxygen, ozone, hydrogen, helium, neon, argon, and krypton. Nitrogen is preferred.

[0029] As a preferred embodiment of this application, the volume ratio of the gas to the liquid medium is 0.03 to 0.05:1.

[0030] As a preferred embodiment of this application, the liquid inlet pressure of the Chinese jet injector in step 1 does not exceed 5 bar.

[0031] As a preferred embodiment of this application, the liquid inlet pressure of the Chinese jet injector in step 1 is 2.2~3.2 bar.

[0032] As a preferred embodiment of this application, the liquid inlet pressure of the Chinese jet injector in step 1 is 3 bar.

[0033] As a preferred embodiment of this application, the liquid inlet velocity of the Chinese jet injector in step 1 is 2~10 m / s. Preferably, it is 3.6 m / s.

[0034] As a preferred embodiment of this application, the gas inlet velocity of the Chinese jet injector in step 1 is 15~30 L / min. More preferably, it is 15~20 L / min. Even more preferably, it is 15 L / min.

[0035] As a preferred embodiment of this application, the secondary gas-liquid mixture is fed into the hydrocyclone at a tangential velocity of 6~10 m / s.

[0036] As a preferred embodiment of this application, the liquid medium in step 1 is a chemical used for photovoltaic cleaning. The liquid medium can be an alkaline solution, hydrofluoric acid (HF) solution, or other chemicals, such as 3-25 wt% KOH solution, or other commonly used cleaning solutions. The formula is: TX-10 surfactant (2 wt%) + triethanolamine oleic acid soap (2 wt%) + potassium hydroxide (2 wt%) + sodium silicate (1 wt%). Its function is to remove grease and heavy metal ions without corroding the silicon wafer. The hydrofluoric acid (HF) solution is used to dissolve the natural oxide film and remove metal adhesions such as Al / Fe / Zn. Photovoltaic panel surface cleaning agents are classified into neutral cleaners, acidic emergency treatment agents, and alkaline emergency treatment agents.

[0037] As a preferred embodiment of this application, the packed tower in step 2 needs to be vented during operation.

[0038] As a preferred embodiment of this application, the nanobubbles in the nanobubble liquid in step 4 have a diameter ≤100 nm and a concentration ≥0.79×10⁻⁶. 8 Cells / mL, half-life > 18h.

[0039] As a preferred embodiment of this application, the nanobubbles in the nanobubble liquid in step 4 have a diameter ≤100 nm and a concentration ≥1.15×10⁻⁶. 8 Cells / mL, half-life > 24h.

[0040] This application utilizes the kinetic energy (high-speed shear) of the jet injector → the mechanical energy (collision) of the packed tower → the centrifugal energy of the hydrocyclone → the cavitation energy of the collisioner, superimposing energy at each stage to achieve multi-stage energy input, compensating for insufficient inlet pressure. This allows for the preparation of nanobubble liquids under low-pressure environments. The possible mechanism is as follows: (1) The liquid medium is first sent into the ejector, which can generate the Venturi effect in the ejector and form a negative pressure zone. The gas that is sucked in is initially broken by the high-speed shear force, and the broken bubbles form a primary gas-liquid mixture with the liquid medium in the ejector. (2) The primary gas-liquid mixture is fed into the packed tower for secondary shearing and collision to form a secondary gas-liquid mixture containing submicron-sized bubbles. Since the packed tower is filled with porous materials (such as Raschig rings, Pall rings, or wire mesh), the following processes can occur when the primary gas-liquid mixture passes through the packed tower: Turbulence enhancement: The perturbation of the flow field on the packing surface increases the local shear rate; Bubble collision: Bubbles collide with the surface of the filler or with each other, further breaking them up.

[0041] Extended gas-liquid contact time: The tortuous path of the packed tower prolongs the residence time, promoting gas dissolution; (3) When the secondary gas-liquid mixture is fed into the hydrocyclone through the tangential inlet, a high-speed rotating flow field is generated. Under the action of centrifugal force, gas-liquid separation and bubble refinement are achieved to obtain a tertiary gas-liquid mixture. In this process, the bubbles are classified: larger bubbles are thrown to the wall and broken, while the small bubbles are concentrated in the central region; shear enhancement: the high shear rate (>10) inside the cyclone 4 s⁻¹) Further reduce the bubble size to the nanoscale edge; (4) The three-stage gas-liquid mixture undergoes cavitation and final breakup in the collider. The three-stage gas-liquid mixture generates cavitation effect and micro-jet impact in the collider. The cavitation effect is caused by the sudden drop in local pressure when the high-speed fluid hits the obstacle, which generates a transient high-pressure shock wave (>100 MPa) that breaks the bubble to the nanoscale (<100 nm). Micro-jet impact: the micro-jet (velocity>100 m / s) generated when the bubble collapses tears apart adjacent bubbles.

[0042] Compared with the prior art, the beneficial effects of this application are: 1. This application achieves multi-stage energy input by progressively superimposing energy through the kinetic energy (high-speed shear) of the jet generator → the mechanical energy (collision) of the packed tower → the centrifugal energy of the hydrocyclone → the cavitation energy of the collider, thus compensating for insufficient inlet pressure and enabling the preparation of nanobubble liquid under low-pressure conditions. 2. Local pressure fluctuations within the device (such as the low-pressure zone at the center of the hydrocyclone and the collision cavitation zone) can briefly reach high-pressure conditions, promoting gas supersaturation and nanobubble nucleation, thereby forming a dynamic pressure gradient within the device, which is beneficial for the stepwise superposition of energy. 3. In this application, after the gas is broken into bubbles by the ejector, it continues to be refined in subsequent stages, rather than relying on a single high-pressure crushing process. This achieves energy superposition and synergistic effect, resulting in a significant reduction in energy consumption. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of a low-pressure preparation device for nanobubble liquid according to an embodiment of the present invention.

[0044] Figure 2 This is a schematic diagram of the structure of a Venturi jet generator according to an embodiment of the present invention.

[0045] Figure 3 This is a schematic diagram of the structure of a hydrocyclone according to an embodiment of the present invention.

[0046] Figure 4 This is a schematic diagram of the internal structure of a redispersion unit according to an embodiment of the present invention.

[0047] Figure 5 This is a schematic diagram of the internal structure of the redistribution unit according to another embodiment of the present invention.

[0048] Figure 6 This is a schematic diagram of the collider in one embodiment of the present invention.

[0049] Figure 7 This is a schematic diagram of the structure of a photovoltaic cleaning system according to an embodiment of the present invention.

[0050] Figure 8 This is a particle size distribution diagram of the bubbles in the nanobubble liquid prepared in Example 1 of this utility model.

[0051] In the picture: 1-Low-pressure preparation device for nano-bubble liquid; 11-Liquid inlet pipe; 12-Venturi jet injector; 121-Liquid inlet jet section; 122-Throat; 1221-Air inlet; 123-Liquid outlet diffusion section; 13-Packed tower; 131-First pipe; 132-Second pipe; 133-Circulation pipe; 14-Hydrocyclone; 141-Hydrocyclone separation unit; 1411-Cylindrical separation chamber; 1412-Conical separation chamber; 1413-Tangential inlet; 1414-Underflow port; 142-Redispersion unit; 1421-Remixing chamber; 1422-Straight pipe section of equal diameter; 15-Collider; 151-Shell; 152-Collision structure; 153-Inlet... 154 - Liquid outlet; 155 - Extension pipe; 16 - Liquid outlet pipe; 171 - Exhaust control assembly; 1710 - Exhaust pipeline; 1711 - Pneumatic valve; 1712 - First throttle valve; 172 - Intake control assembly; 1721 - Intake control valve; 1722 - Second throttle valve; 1723 - Air-opening valve; 1724 - Pressure recorder and controller; 2 - Liquid storage tank; 3 - Delivery pipe; 4 - Magnetic pump; 5 - Gas storage tank; 6 - Gas delivery pipe. Detailed Implementation

[0052] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0053] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0054] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this utility model does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this utility model.

[0055] The present application will be further described below with reference to specific embodiments, but the scope of protection of the present application is not limited thereto.

[0056] like Figure 1 As shown, this application provides a low-pressure preparation device 1 for nanobubble liquid, including an inlet pipe 11, a Venturi jet injector 12, a packed tower 13, a cyclone separator 14, a collisioner 15, and an outlet pipe 16 connected sequentially in the direction of liquid medium flow, wherein: The liquid inlet pipe 11 is configured to transport liquid media; The Venturi jet 12 has its liquid inlet, liquid outlet and gas inlet connected to the liquid inlet pipe, the packed tower and the compressed gas source respectively, and is configured to form a primary gas-liquid mixed flow through gas-liquid mixing. The packed tower 13 is filled with packing material. The inlet and outlet of the packed tower 13 are connected to the jet ejector and the cyclone separator, respectively. It is configured to perform secondary shearing and collision on the primary gas-liquid mixture to form a secondary gas-liquid mixture. The hydrocyclone 14 has its tangential inlet and outlet connected to the packed tower and the collisioner, respectively. The hydrocyclone is equipped with a redisper unit and is configured to perform gas-liquid separation on the secondary gas-liquid mixture. After separation, the bubbles are refined and mixed with the liquid medium to form a tertiary gas-liquid mixture. Collider 15, whose inlet and outlet are connected to hydrocyclone and outlet pipe respectively, is configured to cavitate and ultimately break up the three-stage gas-liquid mixture to form nanobubble liquid. The liquid outlet tube 16 is configured to output nanobubble liquid.

[0057] like Figure 2 As shown, the low-pressure preparation device 1 for nanobubble liquid also includes a control unit, which includes: The exhaust control assembly 171 includes an exhaust pipe 1710 connected to the packed tower 13 and a pneumatic valve 1711 and a first throttle valve 1712 disposed on the exhaust pipe 1710. The pneumatic valve 1711 and the first throttle valve 1712 are electrically connected to the controller and are used to regulate the gas flow rate in the exhaust pipe 1710. The intake control assembly 172 includes an intake control valve 1721 disposed on the gas delivery pipe, the intake control valve being electrically connected to a controller for regulating the gas flow rate within the gas delivery pipe; and The controller is electrically connected to the liquid inlet control component, the air inlet control component 172, and the exhaust control component 171, and is used to control the operation of the low-pressure nanobubble liquid preparation device.

[0058] In some other embodiments of this application, the low-pressure preparation device 1 for nanobubble liquid further includes a liquid discharge control component, which includes a liquid discharge control valve disposed on a liquid discharge pipe. The liquid discharge control valve is electrically connected to a controller and is used to regulate the flow rate of the nanobubble liquid in the liquid discharge pipe.

[0059] In other embodiments of this application, the low-pressure nanobubble liquid preparation device 1 further includes a control unit, the control unit comprising: The liquid inlet control assembly 171 includes a liquid inlet control valve and a first flow meter disposed on the liquid inlet pipe. The liquid inlet control valve and the first flow meter are electrically connected to the controller and are used to regulate the flow rate and velocity of the liquid medium in the liquid inlet pipe. The air intake control assembly 172 includes an air intake control valve 1721 and a second flow meter disposed on the air supply pipe 6. The air intake control valve and the first flow meter are electrically connected to the controller and are used to regulate the gas flow rate and velocity in the air supply pipe. The liquid discharge control component includes a liquid discharge control valve and a third flow meter mounted on a liquid discharge pipe. The liquid discharge control valve and the third flow meter are electrically connected to a controller and are used to regulate the output flow rate and velocity of the nanobubble liquid within the liquid discharge pipe. The controller is electrically connected to the liquid inlet control component, the air inlet control component, and the liquid outlet control component, and is used to control the operation of the low-pressure nanobubble liquid preparation device.

[0060] like Figure 1 As shown, the gas pipeline is also equipped with a second throttle valve 1722, a gas-opening valve 1723, and a pressure recording controller 1724 to monitor and stabilize the pipeline pressure in real time.

[0061] like Figure 3 As shown, the Venturi jet injector 12 includes a liquid inlet jet section 121, a throat 122, and a liquid outlet diffuser section 123 connected in sequence, wherein: The liquid inlet jet section 121 is conical, with its small diameter end connected to the first end of the throat tube and its large diameter end connected to the liquid inlet pipe, for injecting liquid medium into the throat tube. The throat tube 122 is cylindrical and has an air inlet 1221 on its side. The air inlet 1221 is connected to the air source through an air supply pipe and is used to inject the gas drawn in under negative pressure at the throat tube into the liquid medium flowing through the throat tube. The liquid outlet diffusion section 123 is conical, with its small diameter end connected to the second end of the throat tube and its large diameter end connected to the packed tower. It is used to transport the primary gas-liquid mixture containing micron-sized bubbles to the packed tower.

[0062] like Figure 1 As shown, the angle between the injection direction of the liquid in the Venturi jet 12 and the input direction of the gas can be set to 90°.

[0063] In some embodiments of this application, the Reynolds number Re ≥ 10000 is the Reynolds number of the high Reynolds number turbulence formed in the negative pressure zone of the Venturi jet 12.

[0064] like Figure 1 As shown, the packed tower 13 includes a tower body, the top of which is provided with a gas phase outlet, an exhaust port and a feed port. The gas phase outlet is configured to discharge the treated gas phase medium, the exhaust port is connected to the atmosphere, and the feed port is connected to the liquid phase outlet of the Venturi jet through a first pipe 131. The bottom of the tower body is provided with a discharge port and a gas phase inlet. The discharge port is connected to the tangential inlet 1413 of the hydrocyclone 14 through a second pipe 132, and the gas phase inlet forms a gas phase medium circulation channel with the gas phase outlet through a circulation pipe 133.

[0065] In some embodiments of this application, a distributor is provided inside the tower body.

[0066] In some embodiments of this application, the tower body is filled with a porous material, such as Raschig rings, Pall rings, or wire mesh. Pall rings are preferred, and are packed in bulk with a porosity ≥91%.

[0067] In some embodiments of this application, the exhaust port of the packed tower is connected to an exhaust pipe 171, and the outlet of the exhaust pipe 171 is equipped with a pneumatic valve 172 and a first throttle valve 173, which can realize slow exhaust.

[0068] In some embodiments of this application, the height of the packed tower 13 is ≥1100mm.

[0069] In some embodiments of this application, the packed tower is equipped with a level gauge to monitor the upper and lower liquid levels inside the tower. When the liquid level drops to the lower level, the pneumatic valve at the vent pipe of the packed tower is opened to vent the liquid. To reduce pressure fluctuations, a first throttle valve is installed at the outlet of the vent pipe to release the liquid slowly and quantitatively. The pneumatic valve is closed when the liquid level reaches the upper level.

[0070] like Figure 3 , Figure 4 and Figure 5 As shown, the hydrocyclone 14 includes a hydrocyclone separation unit 141 and a redispersion unit 142. The hydrocyclone separation unit 141 includes a cylindrical separation chamber 1411 connected axially and a conical separation chamber 1412 that gradually narrows from the bottom of the cylindrical body and communicates with the inner cavity of the cylindrical body. The side wall of the cylindrical separation chamber is provided with a tangential inlet 1413, and the bottom of the conical separation chamber 1412 is provided with an underflow outlet 1414. The redispersion unit 142 includes a variable diameter flow channel structure. The fluid channel is a variable diameter channel. Its inlet end is sealed and connected to the underflow outlet through a flange connector, and its outlet end is connected to the collider inlet through a quick connector. The variable diameter flow channel includes at least two remixing chambers 1421, and adjacent remixing chambers are transitionally connected by a straight pipe section 1422 of equal diameter.

[0071] In some embodiments of this application, the ratio of the minimum diameter to the maximum diameter of the cyclone separation unit is greater than 1 / 4.

[0072] like Figure 6 As shown, the collider 15 includes a housing 151 and a collision structure 152. The housing 151 is provided with a collision cavity, and the housing 151 is provided with an inlet 153 and an outlet 154 communicating with the collision cavity. The collision structure 152 is a collision plate or perforated plate disposed in the housing.

[0073] In some embodiments of this application, there are at least two liquid inlets, the axes of which all pass through the center of the collision cavity to form an intersecting structure, and the liquid outlets are symmetrically distributed on the sidewalls of the shell.

[0074] In some embodiments of this application, the inner end of the liquid inlet 153 is connected to an extension tube 155 for delivering liquid to the central region of the housing.

[0075] In some embodiments of this application, the collision structure 152 is a collision plate, and an annular medium channel is formed between the outer edge or inner edge of the collision plate and the inner wall of the shell, with the channel width being 1 / 10 to 1 / 5 of the diameter of the collision cavity.

[0076] In some embodiments of this application, the collision structure 152 is an orifice plate with micropores. The micropores on the orifice plate have a diameter of 50-200 nm and a porosity of ≥60%, and are arranged radially or in a matrix. When the collision structure is an orifice plate, the liquid forms a jet through the micropores of the orifice plate and converges and collides at the center of the cavity to generate a vortex. After the three-stage gas-liquid mixture is fed into the collisioner, it impacts the collision structure. The sudden drop in local pressure triggers cavitation, generating a transient high-pressure shock wave (>100 MPa), which breaks the bubbles to the nanoscale. The microjet generated when the bubbles collapse has a velocity >100 m / s, tearing apart adjacent bubbles and further breaking them to the nanoscale.

[0077] In some embodiments of this application, the outlet end of the liquid outlet pipe is equipped with a nozzle for spraying nanobubble water onto the surface of the photovoltaic product to be cleaned, thereby removing and cleaning dust or contaminants from the surface. In use, a controllable gas and liquid medium are mixed in an ejector to obtain a primary gas-liquid mixture. This primary gas-liquid mixture then undergoes secondary shearing and collision in a packed tower to obtain a secondary gas-liquid mixture. This secondary mixture is then fed into a hydrocyclone for gas-liquid separation and refinement, resulting in a tertiary gas-liquid mixture containing nanobubbles. Finally, this tertiary mixture is fed into a collisioner for cavitation and final breakup to obtain nanobubble liquid. The nanobubble liquid is then sprayed onto the surface of the photovoltaic product to be cleaned using a nozzle, thereby removing and cleaning dust or contaminants from the surface.

[0078] In some embodiments of this application, the low-pressure preparation device for nanobubble liquid further includes a reflux pipe and a reflux control valve disposed on the reflux pipe. One end of the reflux pipe is connected to the liquid outlet pipe, and the other end of the reflux pipe is connected to the liquid inlet pipe, for returning substandard nanobubble liquid to the ejector; the reflux control valve is electrically connected to the controller.

[0079] like Figure 7 As shown, this application also provides a photovoltaic cleaning system, including: Storage tank 2 is used to store liquid media; The delivery pipe 3 is connected to the liquid storage tank 2 and the magnetic pump 4 respectively, and is used to deliver the liquid medium in the liquid storage tank 2 to the magnetic pump. The magnetic pump 4 is connected to the delivery pipe 3 and the low-pressure preparation device 1 for nanobubble liquid, respectively, and is used to pressurize the liquid medium output from the storage tank and deliver it to the low-pressure preparation device 1 for nanobubble liquid. A low-pressure nanobubble liquid preparation device 1 is connected to a magnetic pump 4 and a gas source, respectively, for forming a nanobubble liquid; and The gas storage tank 5 is connected to the low-pressure preparation device 1 for nanobubble liquid via the gas supply pipe 6, and is used to supply gas into the low-pressure preparation device 1 for nanobubble liquid.

[0080] In some embodiments of this application, the liquid storage tank is made of corrosion-resistant material and is used to store chemicals used in photovoltaic cleaning. Example 1

[0081] The method for preparing high-density nanobubble liquid under low pressure using the nanobubble liquid low-pressure preparation device of this invention includes the following steps: Step 1, Primary Jet Breaking: N2 and a 5wt% KOH solution are fed into a Venturi jet injector at a volume ratio of 0.05:1. Under the shear force of the liquid medium, the gas undergoes primary breakage to form micron-sized bubbles with an average particle size of 10~100 μm. The micron-sized bubbles mix with the liquid medium in the jet injector to form a primary gas-liquid mixture containing the micron-sized bubbles. The inlet pressure of the liquid medium is 3 bar, the inlet velocity of the liquid phase medium is 3.6 m / s, and the flow rate of N2 at the gas phase inlet is 15 L / min. Step 2, Turbulent Refining: The primary gas-liquid mixture is sprayed from the top of the tower at a speed of 340 m through a distributor. 3 / (m 2 The spray density of h) is delivered to the packed tower. The primary gas-liquid mixture flows from top to bottom through the packing layer and undergoes secondary shearing and collision. Under the condition of Reynolds number Re > 10000, the bubbles are subjected to secondary shearing and breaking to obtain a secondary gas-liquid mixture containing submicron-sized bubbles. The average particle size of the submicron-sized bubbles in the secondary gas-liquid mixture is 100~500 nm.

[0082] Specifically, the packed tower has a height >1100mm, and its interior is filled with Pall rings in a bulk manner with a porosity ≥91%. The primary gas-liquid mixture flows from top to bottom through the packing layer at the top of the packed tower, which prolongs the residence time of the primary gas-liquid mixture in the tortuous path of the packed tower, promoting gas dissolution. During the process of delivering the primary gas-liquid mixture to the packed tower, venting is required. The liquid level in the tower is monitored by a level gauge inside the packed tower. When the liquid level drops to the low level, the pneumatic valve is opened to begin venting. To reduce pressure fluctuations, the outlet of the venting pipe has a first throttle valve for slow venting. The pneumatic valve is closed when the liquid level reaches the upper level.

[0083] Step 3, Cyclone Recombination: The secondary gas-liquid mixture is fed into a hydrocyclone at a tangential velocity of 8 m / s to break up and redisperse the bubbles, thereby obtaining a tertiary gas-liquid mixture containing nanobubbles; the average particle size of the transition state nanobubbles in the tertiary gas-liquid mixture is 50~200 nm.

[0084] In this step, the secondary gas-liquid mixture enters the cyclone separation unit of the hydrocyclone through a tangential inlet, generating high-speed rotating flow and forming a centrifugal force field. The liquid and gas stratify within the hydrocyclone, with the gas, due to its lower density, accumulating towards the central axis. The fluid velocity gradient inside the hydrocyclone is extremely large (especially within the conical separation chamber), creating a strong shear force field. Under the action of shear force, the gas is torn into tiny bubbles. The turbulent vortices in the cyclone further break the bubbles down to the nanoscale (typically <1 μm), and after flowing out from the underflow port of the cyclone separation unit, they are sent to the redispersion unit. Due to the multiple changes in the fluid channel diameter of the redispersion unit, the pressure changes multiple times, inducing local cavitation, generating bubble nuclei, and promoting the formation of nanobubbles. Finally, a tertiary gas-liquid mixture containing transition-state nanobubbles is formed, and it is sent from the outlet of the redispersion unit into the collider.

[0085] Step 4, cavitation treatment: The three-stage gas-liquid mixture is fed into the collider for cavitation and collision breakup to obtain a nanobubble liquid containing nanobubbles; the nanobubble half-life refers to the time required for the bubble concentration to drop to 50% of the initial value under specific conditions (such as standing at 25°C).

[0086] In this embodiment, the particle size distribution and half-life of the nanobubbles in the nanobubble liquid were determined by nanoparticle tracking analysis (NTA), and the concentration was measured by dynamic light scattering (DLS). The average particle size of the nanobubbles in the nanobubble liquid was 80 nm, and the concentration was 1.15 × 10⁻⁶. 8 The concentration was [number] cells / mL, and the half-life was 24 h. The test results are shown in Table 1 and [other tables]. Figure 8 . Example 2

[0087] The difference between this embodiment and Embodiment 1 is that the volume ratio of the gas and liquid media is different. In this embodiment, the volume ratio of the gas and liquid media is 0.01:1, while the rest is the same as in Embodiment 1. Example 3

[0088] The difference between this embodiment and Embodiment 1 is that the volume ratio of the gas and liquid media is different. In this embodiment, the volume ratio of the gas and liquid media is 0.2:1, while the rest is the same as in Embodiment 1. Example 4

[0089] The difference between this embodiment and Embodiment 1 is that the inlet pressure of the Venturi jet is different. In this embodiment, the inlet pressure of the Venturi jet is 2.2 bar, while the rest is the same as in Embodiment 1. Example 5

[0090] The difference between this embodiment and Embodiment 1 is that the inlet pressure of the Venturi jet is different. In this embodiment, the inlet pressure of the Venturi jet is 3.2 bar, while the rest is the same as in Embodiment 1. Example 6

[0091] The difference between this embodiment and Embodiment 1 is that the type of gas is different. In this embodiment, the gas is O2, while the rest is the same as in Embodiment 1.

[0092] Comparative Example 1 The difference between this comparative tower and Example 1 is that the packed tower was not vented; otherwise, they are the same as Example 1.

[0093] Comparative Example 2 The installation sequence of some equipment in the low-pressure preparation device for nanobubble liquid in this comparative example is different from that in Example 1. Specifically, the inlet pipe, Venturi jet, cyclone separator, packed tower, collisioner and outlet pipe are connected in sequence by pipelines according to the direction of liquid medium flow. The rest are the same as in Example 1.

[0094] Comparative Example 3 The low-pressure preparation apparatus for nanobubble liquid in this comparative example differs from that in Example 1. This comparative example lacks a packed tower, but everything else is the same as in Example 1.

[0095] Table 1. Performance of Nanobubble Fluid The experimental results from Examples 1-3 show that the volume ratio of gas to liquid medium affects the quality of the nanobubble liquid. The higher the volume ratio of gas to liquid medium, the smaller the average particle size of the bubbles in the prepared nanobubble liquid. A decrease in the gas-liquid ratio directly reduces the gas content per unit volume of liquid, resulting in a decrease in the number of nanobubbles. Moreover, at a lower gas-liquid ratio, the cavitation effect of the Venturi jet weakens, the average diameter of the generated bubbles increases, and the particle size distribution changes from a single peak to a multi-peak. Conversely, an increase in the gas-liquid ratio significantly increases the gas content per unit volume of liquid, causing the number of nanobubbles to increase exponentially. Experiments show that when the gas-liquid ratio increases from 0.01:1 to 0.05:1, the bubble concentration increases by nearly 30%, while when the gas-liquid ratio increases from 0.05:1 to 0.2:1, the bubble concentration increases by less than 10%. However, as the gas-liquid ratio increases, some bubbles will merge, making the stability mechanism of the nanobubble liquid more easily disrupted, reducing the surface charge density of the bubbles, and weakening the stability of the electric double layer. Meanwhile, the increased Ostwald ripening rate accelerates the mass transfer from small bubbles to large bubbles, which reduces the half-life of the nanobubble liquid and thus affects the overall bubble generation efficiency. Therefore, the gas-liquid volume ratio (G / L) needs to be controlled between 0.01 and 0.2.

[0096] As can be seen from Examples 1, 4, and 5, the inlet pressure of the Venturi jet injector also affects the quality of the nanobubble liquid. Higher inlet pressure increases the jet shear force, significantly reducing the average bubble diameter. Data from the examples show that when the inlet pressure increases from 2.2 Bar to 3 Bar, the average bubble size decreases from 98 nm to 80 nm, and the number of bubbles per unit volume increases by nearly 17%. When the inlet pressure increases from 3 Bar to 3.2 Bar, the average bubble size decreases from 80 nm to 72 nm, while the concentration and distribution improve, increasing the number of bubbles per unit volume by nearly 30%, and the particle size distribution becomes more concentrated.

[0097] As can be seen from Examples 1 and 6, under the same generation conditions, the average particle size of oxygen bubbles is larger and the distribution is more uniform than that of nitrogen bubbles. This is because the higher solubility of oxygen promotes more uniform nucleation. Nitrogen nanobubbles have a smaller average particle size but a wider distribution range. Nitrogen molecules have strong polarization ability and better charge stability at the bubble interface, which inhibits coarsening caused by aggregation.

[0098] As can be seen from Examples 1, 1, and 3, the presence or absence of a packed tower and whether or not the packed tower is vented directly affect the generation of nanobubbles. If the packed tower is not vented, micron-sized bubble liquid is ultimately generated. This is mainly because turbulence occurs when the gas-liquid mixture flows through, forming a disturbed flow field on the packing surface and increasing the local shear rate. During the movement, bubbles collide with each other or with the packing surface, further breaking them down to the submicron level (100-500 nm). The gas-liquid contact time is prolonged: the tortuous path of the packed tower prolongs the residence time, promoting gas dissolution. Moreover, the packed tower needs to be vented in time during preparation, which can only generate micron-sized bubbles. This may be because the unvented gas accumulates in the gaps between the packing layers, and with the flow of the liquid phase or temperature changes, the gas volume expands to form larger bubbles. Furthermore, when the gas and liquid flow counter-currently in the packed tower, a low-pressure zone may form in the unvented area, causing dissolved gas to precipitate and merge into large bubbles, thus significantly increasing the bubble size.

[0099] As can be seen from Example 1 and Comparative Example 2, the installation sequence of each component affects the quality of the prepared nanobubble liquid. Inlet pipe → Venturi jet injector: The Venturi jet injector uses high-speed fluid to generate negative pressure to draw in gas, forming a preliminary gas-liquid mixture. If other equipment is placed before this, it will lead to insufficient gas supply, affecting the bubble generation efficiency. Venturi jet injector → Packed tower: The packed tower increases the gas-liquid contact area through the packing layer, enhancing the mass transfer effect. Premixing by the jet injector is necessary; otherwise, uneven gas-liquid distribution will reduce the efficiency of the packed tower. Packed tower → Hydrocyclone: ​​The hydrocyclone uses centrifugal force to further break up the bubbles. If directly connected to the jet injector, insufficiently mixed gas and liquid will lead to a decrease in swirling shearing efficiency; Swirler → Collider: The collider nanoscales the bubbles through physical impact, and the pre-swirling can reduce bubble aggregation and improve collision breakup efficiency; Collider → Outlet Pipe: The bubble state needs to be stabilized before final liquid outflow to avoid particle size rebound caused by pipeline disturbance; Overall Logic: This sequence follows a progressive processing flow of "premixing → mass transfer enhancement → shear breakup → nanoscale → stable output", which greatly reduces the stability of bubbles in the formed bubble liquid, results in a narrow particle size distribution, optimizes energy consumption and bubble density, and reduces Reduce the amount of cleaning solution used; in Comparative Example 2, the order of the packed tower and hydrocyclone was changed, with the hydrocyclone placed first. This caused uneven gas-liquid mixing, leading to an imbalance in centrifugal force distribution and exacerbated bubble aggregation, resulting in a sharp increase in the average bubble size, which rebounded from 80nm to 657nm. This shows that the component sequence must strictly follow the process logic of "pressure construction → gas-liquid mixing → mass transfer enhancement → mechanical crushing → fine processing → stable output". Any misalignment will lead to a significant deterioration in bubble stability, energy consumption, or processing efficiency. Moreover, this application achieves multi-stage energy input by progressively superimposing energy through the kinetic energy (high-speed shear) of the jet → the mechanical energy (collision) of the packed tower → the centrifugal energy of the hydrocyclone → the cavitation energy of the collider. This compensates for insufficient inlet pressure and can prepare nanobubble liquid under low-pressure environment. It has low energy consumption, high energy utilization rate, and is suitable for large-scale industrial production.

[0100] The above embodiments are for illustrating the implementation schemes disclosed in this application and should not be construed as limiting this application. Furthermore, various modifications listed herein, as well as variations in methods and compositions of the utility model, will be apparent to those skilled in the art without departing from the scope and spirit of this application. Although this application has been specifically described in conjunction with various specific preferred embodiments, it should be understood that this application should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the utility model should be included within the scope of this application.

Claims

1. A nano bubble liquid low pressure preparation device, characterized in that, It includes an inlet pipe (11), a Venturi jet injector (12), a packed tower (13), a hydrocyclone (14), a collisioner (15), and an outlet pipe (16) connected sequentially in the direction of the original cleaning solution flow, wherein: The inlet pipe (11) is configured to transport liquid media; The Venturi jet (12) has its liquid inlet, liquid outlet and gas inlet connected to the liquid inlet pipe, the packed tower and the compressed gas source respectively, and is configured to form a primary gas-liquid mixture flow through gas-liquid mixing. The packed tower (13) is filled with packing material. The inlet and outlet of the packed tower (13) are connected to the Venturi jet and the cyclone separator, respectively. It is configured to perform secondary shearing and collision on the primary gas-liquid mixture to form a secondary gas-liquid mixture. The hydrocyclone (14) has its tangential inlet and outlet connected to the packed tower and the collisioner, respectively. The hydrocyclone is equipped with a redisper unit and is configured to perform gas-liquid separation on the secondary gas-liquid mixture. After separation, the bubbles are refined and mixed with the liquid medium to form a tertiary gas-liquid mixture. Collider (15), whose inlet and outlet are connected to hydrocyclone and outlet pipe respectively, is configured to cavitate and break up the three-stage gas-liquid mixture to form a nanobubble liquid containing nanobubbles. The liquid outlet tube (16) is configured to output nano bubble liquid.

2. The low-pressure nano bubble liquid preparation device according to claim 1, wherein It also includes a control unit (17), which includes: The exhaust control assembly (171) includes an exhaust pipe (1710) connected to the packed tower (13) and a pneumatic valve (1711) and a first throttle valve (1712) disposed on the exhaust pipe (1710). The pneumatic valve (1711) and the first throttle valve (1712) are electrically connected to the controller and are used to regulate the gas flow rate in the exhaust pipe (1710). The intake control assembly (172) includes an intake control valve (1721) disposed on the gas delivery pipe, the intake control valve being electrically connected to a controller for regulating the gas flow rate within the gas delivery pipe; and The controller is electrically connected to the liquid inlet control component, the air inlet control component (172), and the exhaust control component (171) and is used to control the operation of the nanobubble liquid low-pressure preparation device.

3. The low-pressure preparation device for nanobubble liquid according to claim 1, characterized in that: The cyclone separator (14) includes a cyclone separation unit (141) and a redispersion unit (142). The cyclone separation unit (141) includes a cylindrical separation chamber connected axially and a conical separation chamber that gradually narrows from the bottom of the cylindrical body and communicates with the inner cavity of the cylindrical body. The side wall of the cylindrical separation chamber is provided with a tangential inlet (1411), and the bottom of the conical separation chamber is provided with an underflow outlet (1412). The redispersion unit (142) includes a variable diameter channel. The variable diameter channel is a variable diameter channel. Its inlet end is sealed and connected to the underflow outlet through a flange connector, and its outlet end is connected to the inlet of the collider through a quick connector. The variable diameter channel contains at least two remixing chambers, and adjacent remixing chambers are connected by a straight pipe section of equal diameter.

4. The low-pressure nano bubble liquid preparation device according to claim 1, characterized in that: The packed tower (13) includes a tower body, the top of which is provided with a gas phase outlet, an exhaust port and a feed port. The gas phase outlet is configured to discharge the treated gas phase medium. The exhaust port is connected to the atmosphere. The feed port is connected to the liquid outlet of a Venturi jet through a first pipe. The bottom of the tower body is provided with a discharge port and a gas phase inlet. The discharge port is connected to the tangential inlet of a hydrocyclone through a second pipe. The gas phase inlet forms a gas phase medium circulation channel with the gas phase outlet through a circulation pipeline.

5. The low-pressure nano bubble liquid preparation device according to claim 4, characterized in that: The packed tower is filled with a porous material, which is Raschig rings, Pall rings, or wire mesh.

6. The low-pressure preparation device for nanobubble liquid according to claim 1, characterized in that: The collider (15) includes a housing and a collision structure disposed within the housing. The housing is provided with an inlet and an outlet, and the collision structure is located at the outlet.

7. The low-pressure preparation device for nanobubble liquid according to claim 1, characterized in that: It also includes a reflux pipe and a reflux control valve installed on the reflux pipe. One end of the reflux pipe is connected to the liquid outlet pipe, and the other end of the reflux pipe is connected to the liquid inlet pipe, which is used to return the substandard nanobubble liquid to the Venturi jet injector; the reflux control valve is electrically connected to the controller. 8.The low-pressure nano bubble liquid preparation device according to claim 1, characterized in that: The outlet end of the outlet pipe is equipped with a nozzle.

9. A photovoltaic cleaning system, characterized in that: include: Storage tank (2) is used to store cleaning solution; The delivery pipe (3) is connected to the storage tank (2) and the magnetic pump (4) respectively, and is used to deliver the cleaning solution in the storage tank (2) to the magnetic pump. A magnetic pump (4) is connected to a delivery pipe (3) and a low-pressure preparation device (1) for preparing nanobubble liquid according to any one of claims 1 to 8, and is used to pressurize the cleaning raw liquid output from the storage tank (2) and deliver it to the low-pressure preparation device (1) for preparing nanobubble liquid. The low-pressure preparation device (1) for nanobubble liquid is connected to the magnetic pump (4) and the gas storage tank (5) respectively, and is used to mix the gas and the cleaning liquid to form nanobubble liquid; as well as The gas storage tank (5) is connected to the low-pressure preparation device (1) of nanobubble liquid via the gas supply pipe (6) and is used to supply gas into the low-pressure preparation device (1) of nanobubble liquid.

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