A hydroponic and root zone circulating irrigation coupling system for a greenhouse

Abstract

This invention provides a coupled system for greenhouse aeroponics and root zone circulating irrigation, belonging to the field of greenhouse planting irrigation technology. It includes a nutrient solution storage and pretreatment module and a low-pressure / pumpless atomization module. The low-pressure / pumpless atomization module and the root zone circulating irrigation module are connected in parallel to the main supply pipeline via a three-way valve. A reflux purification module is connected to both the root zone circulating irrigation module and the nutrient solution storage and pretreatment module. The low-pressure / pumpless atomization module includes a low-pressure variable frequency pump, an energy storage and stabilizing tank, an ultrasonic atomizer, atomization pipeline, and self-cleaning nozzles. The energy storage and stabilizing tank is located between the low-pressure variable frequency pump and the atomization pipeline. The ultrasonic atomizer is connected in parallel with the atomization pipeline, and the self-cleaning nozzles are spaced along the atomization pipeline. This invention, using the above-mentioned coupled system for greenhouse aeroponics and root zone circulating irrigation, solves the problems of high energy consumption in high-pressure atomization, easy nozzle clogging, unstable nutrient supply, and low nutrient solution utilization rate in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of greenhouse planting irrigation technology, and in particular to a greenhouse aeroponics and root zone circulating irrigation coupling system. Background Technology

[0002] Currently, aeroponics coupled with root zone circulating irrigation systems are widely used in greenhouses, but existing systems have many unresolved problems that seriously affect planting efficiency and energy saving.

[0003] First, existing systems generally employ high-pressure atomization, requiring high-pressure pumps of 1.6-3 MPa. This not only results in extremely high energy consumption, accounting for over 35% of the total greenhouse energy consumption, but also makes the high-pressure pipelines susceptible to fatigue leaks and rapid aging due to prolonged exposure to high pressure. Pipe material costs account for over 30% of the total system investment, leading to high maintenance costs in the long run. Second, high-pressure nozzles are easily clogged by calcium and magnesium ions and impurities in the nutrient solution, typically becoming clogged after about 200 hours of operation. This causes uneven atomization, significant differences in humidity in the root zone, affecting root absorption and consequently leading to uneven crop growth and reduced marketability. Third, existing systems lack effective energy-saving circulation mechanisms. Dead water zones exist during nutrient solution return, resulting in severe wall-mounted losses and a utilization rate of less than 70%. Furthermore, the systems lack redundancy backup designs; in the event of a power outage or high-pressure pump failure, the roots will rapidly lose water and wilt after atomization stops, causing reduced crop yields or even death.

[0004] The existing system's switching between aeroponics and root zone irrigation modes is abrupt and lacks a smooth transition mechanism. The sudden change in the root zone environment during the switch can easily lead to root damage. Furthermore, the coordinated control of atomization and irrigation is insufficient, and it cannot be dynamically adjusted according to the crop growth stage and environmental parameters, which further reduces the system's practicality and energy-saving effect.

[0005] Currently, there is no coupling system that can simultaneously solve the problems of high-pressure energy consumption, blockage, unstable liquid supply, and abrupt mode switching. Therefore, developing a low-pressure / pump-free atomization, energy-efficient, and stable atomization and root zone circulating irrigation coupling system has become an urgent technical challenge. Summary of the Invention

[0006] The purpose of this invention is to provide a greenhouse aeroponics and root zone circulating irrigation coupling system, which solves the problems of high energy consumption of high-pressure atomization, easy clogging of nozzles, unstable liquid supply, abrupt mode switching, and low nutrient solution utilization rate in existing greenhouse aeroponics and root zone circulating irrigation coupling systems.

[0007] To achieve the above objectives, this invention provides a greenhouse aeroponics and root zone circulating irrigation coupling system, including a nutrient solution storage and pretreatment module, a low-pressure / pump-free atomization module, a root zone circulating irrigation module, a reflux purification module, and an intelligent control module; the low-pressure / pump-free atomization module and the root zone circulating irrigation module are connected in parallel to the main supply pipeline via a three-way valve, and the reflux purification module is connected to both the root zone circulating irrigation module and the nutrient solution storage and pretreatment module; the low-pressure / pump-free atomization module includes a low-pressure variable frequency pump, an energy storage and stabilizing tank, an ultrasonic atomizer, an atomization pipeline, and self-cleaning nozzles; the energy storage and stabilizing tank is located between the low-pressure variable frequency pump and the atomization pipeline, the ultrasonic atomizer is connected in parallel with the atomization pipeline, and the self-cleaning nozzles are spaced along the atomization pipeline; The root zone circulating irrigation module includes root zone irrigation pipelines, drip irrigation heads, tiltable planting boards, a collection tank with a guide slope, and a liquid level control valve; the reflux purification module is equipped with a hydrocyclone, a photocatalytic sterilizer, and an ultrafiltration membrane filter in sequence; the intelligent control module is electrically connected to the low-pressure variable frequency pump, the energy storage and stabilizing tank, the ultrasonic atomizer, the three-way valve, the liquid level control valve, and the reflux purification module.

[0008] Preferably, the nutrient solution storage and pretreatment module includes a storage tank, a pretreatment filter, a magnetizing descaling device, a level sensor, and a temperature sensor; the pretreatment filter and the magnetizing descaling device are connected in series in the outlet pipeline of the storage tank, and the level sensor and the temperature sensor are located inside the storage tank and electrically connected to the intelligent control module.

[0009] Preferably, the low-pressure / pumpless atomization module is also equipped with an emergency liquid supply tank, which is connected in parallel with the atomization pipeline and relies on gravity to achieve emergency liquid supply.

[0010] Preferably, the self-cleaning nozzle has rotating blades inside, and the self-cleaning nozzle has a swirling spray structure.

[0011] Preferably, the tilt angle of the planting board is adjustable from 0 to 15°, the bottom slope of the liquid collection tank is 3 to 5°, and the liquid level control valve is located at the outlet of the liquid collection tank.

[0012] Preferably, the photocatalytic sterilizer adopts a combination structure of UV-C lamp tube and TiO2 photocatalytic material, and the ultrafiltration membrane filter adopts a hollow fiber membrane with a pore size of 0.1-0.2μm.

[0013] Preferably, the intelligent control module includes a PLC controller, an environmental sensor, an EC / pH sensor, and a pressure sensor; the EC / pH sensor is located in the liquid storage tank and the return pipeline, respectively, and the pressure sensor is located inside the energy storage and pressure stabilizing tank.

[0014] Preferably, the coupling system adopts an alternating cycle of atomization and irrigation, with the atomization pipeline and irrigation pipeline operating synchronously and under control.

[0015] Therefore, the present invention employs the above-mentioned greenhouse aeroponics and root zone circulating irrigation coupling system, and the technical effects are as follows: 1. Significantly reduced energy consumption: Low-pressure atomization is used instead of traditional high-pressure atomization. Combined with frequency conversion control and ultrasonic pumpless atomization, the system energy consumption is reduced by 50%-70%, and long-term operation can significantly save planting costs. At the same time, the design of the energy storage and pressure stabilizing tank reduces the start and stop frequency of the frequency conversion pump, further reducing energy consumption.

[0016] 2. Solve clogging problems: Through the triple design of pretreatment filtration, magnetization descaling, and self-cleaning nozzles, impurities and scale are reduced from the source.

[0017] 3. Improve operational stability: An emergency liquid supply tank is set up to solve the problem of root water loss caused by power outages or pump failures; closed-loop control of pressure, liquid level, and nutrient solution parameters ensures stable system operation and avoids crop growth due to parameter fluctuations; the planting board can be tilted to solve the problems of root drooping and uneven fogging.

[0018] 4. Improve nutrient solution utilization: The reflux purification module realizes closed-loop circulation of nutrient solution. Through triple purification of hydrocyclone, photocatalytic disinfection and ultrafiltration membrane filtration, the nutrient solution utilization rate is increased to more than 90%, reducing nutrient solution waste and environmental pollution. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a greenhouse aeroponics and root zone circulating irrigation coupling system according to the present invention; Figure 2 This is a schematic diagram of the low-pressure / pumpless atomization module structure of the present invention; Figure 3 This is a schematic diagram of the root zone circulating irrigation module structure of the present invention; Figure 4 This is a schematic diagram of the reflux purification module structure of the present invention.

[0020] Figure Labels 1. Storage tank; 2. Pretreatment filter; 3. Magnetized descaling device; 4. Low-pressure variable frequency pump; 5. Energy storage and pressure stabilizing tank; 6. Ultrasonic atomizer; 7. Atomization pipeline; 8. Self-cleaning nozzle; 9. Emergency supply tank; 10. Root zone irrigation pipeline; 11. Drip irrigation head; 12. Planting board; 13. Collection tank; 14. Liquid level control valve; 15. Return pipeline; 16. Hydrocyclone; 17. Photocatalytic sterilizer; 18. Ultrafiltration membrane filter; 19. Return pump; 20. Sediment outlet. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0023] Example 1 like Figures 1-4 As shown, this invention provides a greenhouse aeroponics and root zone circulating irrigation coupling system. It employs a low-pressure atomization and pump-free auxiliary circulation design, abandoning traditional high-pressure pumps. Combined with a modular structure, self-cleaning anti-clogging design, and intelligent collaborative control, it achieves efficient coupling of aeroponics and root zone circulating irrigation. The system consists of five main modules: a nutrient solution storage and pretreatment module, a low-pressure / pump-free atomization module, a root zone circulating irrigation module, a reflux purification module, and an intelligent control module. These modules are connected via dedicated pipelines, valves, and sensors to form a closed-loop circulation system. The entire process operates at low pressure, and in some scenarios, pump-free atomization can be achieved, significantly reducing energy consumption.

[0024] The nutrient solution storage and pretreatment module is the source of nutrient solution supply for the system, and mainly includes a storage tank 1, a pretreatment filter 2, a magnetized descaling device 3, a level sensor, and a temperature sensor.

[0025] The liquid storage tank 1 is made of food-grade PE material, and its volume is designed according to the area of ​​the greenhouse. The top of the liquid storage tank 1 is equipped with a liquid filling port and an exhaust port, and the bottom is equipped with a sewage discharge port, which facilitates regular cleaning of impurities.

[0026] The pretreatment filter 2 is connected in series in the outlet pipeline of the storage tank 1. It uses a 200-mesh stainless steel filter screen to filter large particulate impurities (such as soil particles and crop residues) in the nutrient solution and prevent impurities from entering the subsequent pipeline and nozzle.

[0027] The magnetizing descaling device 3 is installed after the pretreatment filter 2. It adopts a bipolar magnetization design with a magnetic field strength of 0.3-0.5T. Through magnetization, it destroys the crystal structure of calcium and magnesium ions in the nutrient solution, preventing them from forming scale on the nozzle and pipeline inner wall, thus reducing clogging problems from the source.

[0028] The liquid level sensor and temperature sensor are installed inside the storage tank 1. The liquid level sensor is used to detect the liquid level of the nutrient solution in the storage tank 1 in real time, and the temperature sensor is used to detect the temperature of the nutrient solution. Both are electrically connected to the intelligent control module to realize real-time monitoring of liquid level and temperature.

[0029] The low-pressure / pumpless atomization module is the core energy-saving module of this invention, replacing the traditional high-pressure atomization system. It mainly includes a low-pressure variable frequency pump 4, an ultrasonic atomizer 6, an atomization pipeline 7, a self-cleaning nozzle 8, an energy storage and pressure stabilizing tank 5, and an emergency liquid supply tank 9.

[0030] The low-pressure variable frequency pump 4 adopts variable frequency control, with a rated pressure of 0.3-0.6MPa and a power of 0.5-1.5kW, reducing energy consumption by more than 50% compared to traditional high-pressure pumps. The inlet of the low-pressure variable frequency pump 4 is connected to the outlet of the magnetized descaling device 3 of the pretreatment module through a pipeline, and the outlet is connected to the energy storage and pressure stabilizing tank 5.

[0031] The energy storage and pressure stabilizing tank 5 is used to stabilize the pressure in the pipeline and avoid uneven atomization caused by pressure fluctuations. It has a volume of 10-20L and is equipped with an internal pressure sensor, which is electrically connected to the intelligent control module. When the pipeline pressure is below 0.3MPa, the low-pressure variable frequency pump 4 automatically starts to replenish the pressure. When the pressure is above 0.6MPa, the variable frequency pump automatically stops, achieving adaptive pressure regulation.

[0032] The ultrasonic atomizer 6 is installed at the branch node of the atomization pipeline 7. It uses high-frequency vibration atomization (frequency 20-40kHz) to achieve pump-free atomization, which is suitable for precise atomization in local areas of the greenhouse (such as the seedling area). The ultrasonic atomizer 6 is connected in parallel with the low-pressure atomization pipeline 7, and can be switched according to the needs of the crop to further reduce energy consumption.

[0033] The atomizing pipe 7 is made of PVC and has a diameter of 20-32mm. The pipe is laid on the top of the greenhouse, evenly distributed along the crop planting rows, with a self-cleaning nozzle 8 installed every 50-80cm. The self-cleaning nozzle 8 uses a swirling spray design, with rotating blades inside. During operation, the flow of the nutrient solution drives the blades to rotate, achieving self-cleaning of the nozzle's inner wall and preventing impurities from adhering and scaling. The nozzle has an atomization angle of 120° and an atomized particle size of 50-100μm, ensuring uniform atomization and coverage of the entire root zone.

[0034] The emergency liquid supply tank 9 is connected in parallel with the atomizing pipeline 7. It has a volume of 50-100L and is pre-stored with nutrient solution. When the low-pressure variable frequency pump 4 fails or is powered off, the emergency liquid supply tank 9 automatically supplies liquid to the atomizing pipeline 7 by gravity. The liquid supply time can reach 2-4 hours, which can prevent the roots from losing water and wilting quickly and improve the stability of the system.

[0035] The root zone circulating irrigation module is used to achieve precise irrigation of the root zone. It works in conjunction with the atomization module and mainly includes a root zone irrigation pipeline 10, a drip irrigation head 11, a planting plate 12, a liquid collection tank 13, and a liquid level control valve 14.

[0036] The main pipes of the root zone irrigation pipeline 10 and the atomization pipeline 7 are connected in parallel and connected by a three-way valve, which can realize the switching between aeroponics and root zone irrigation. The irrigation pipeline is laid on both sides of the roots of the crop planting row, with 1-2 drip heads 11 corresponding to each crop. The flow rate of the drip head 11 is 2-5L / h to ensure uniform soil moisture in the root zone.

[0037] The planting board 12 features a tiltable design (tilt angle 0-15°) and is made of PP plastic. Planting holes are provided on the planting board 12, and crops are fixed in these holes using planting baskets, with the roots hanging down above the collection trough 13. The tilt angle of the planting board 12 can be adjusted via an adjustable bracket, facilitating the dispersed distribution of roots to the mist and preventing the inner roots from being unable to collect mist due to clumps of roots hanging down.

[0038] The nutrient solution collection tank 13 is located below the planting plate 12. It has a U-shaped structure, a width of 20-30cm, and a depth of 10-15cm. The bottom of the collection tank 13 is equipped with a guide slope (3-5°) to facilitate the return of nutrient solution and avoid the formation of stagnant water areas. The outlet of the collection tank 13 is connected to the return purification module to realize the recycling of nutrient solution.

[0039] The liquid level control valve 14 is installed at the outlet of the liquid collection tank 13 and is electrically connected to the intelligent control module. It is used to control the liquid level of the nutrient solution in the liquid collection tank 13. When the liquid level is higher than the set value (5-8cm), the valve opens automatically and the nutrient solution flows into the return purification module. When the liquid level is lower than the set value, the valve closes to avoid insufficient humidity in the root zone due to excessively fast return.

[0040] The reflux purification module is used to purify the refluxed nutrient solution to ensure the quality of the nutrient solution for recycling. It mainly includes a reflux pipeline 15, a hydrocyclone 16, a photocatalytic sterilizer 17, an ultrafiltration membrane filter 18, and a reflux pump 19.

[0041] One end of the return pipe 15 is connected to the outlet of the collection tank 13, and the other end is connected to the inlet of the hydrocyclone 16. The diameter of the return pipe 15 is 32-40mm to ensure smooth return of the nutrient solution.

[0042] Hydrocyclone 16 is used to separate suspended impurities (such as root exudates and fine particles) in the reflux nutrient solution, with a separation efficiency of over 90%. The outlet of hydrocyclone 16 is divided into a supernatant outlet and a sediment outlet 20. The sediment outlet 20 is periodically discharged, and the supernatant outlet is connected to the photocatalytic sterilizer 17.

[0043] The photocatalytic sterilizer 17 combines a UV-C lamp (wavelength 254nm) with TiO2 photocatalytic material to kill bacteria, fungi, and other microorganisms in the reflux nutrient solution, achieving a sterilization efficiency of over 99% and preventing systemic diseases caused by microbial proliferation in high-humidity environments. The outlet of the photocatalytic sterilizer 17 is connected to the ultrafiltration membrane filter 18.

[0044] The ultrafiltration membrane filter 18 uses a hollow fiber membrane with a pore size of 0.1-0.2μm to further filter out fine impurities and microbial residues in the nutrient solution, ensuring the purity of the nutrient solution. The outlet of the ultrafiltration membrane filter 18 is connected to the return pump 19, which pumps the purified nutrient solution back to the storage tank 1, forming a closed loop circulation and increasing the nutrient solution utilization rate to over 90%.

[0045] The intelligent control module is used to realize the automated control of the system and coordinate the work of various modules. It mainly includes controllers, environmental sensors, EC / pH sensors and actuators.

[0046] The controller, a PLC controller, has data acquisition, logic judgment, and command output functions, and is the control core of the system. The controller is electrically connected to all sensors and actuators, receives data collected by the sensors in real time, and outputs control commands according to preset logic.

[0047] The environmental sensors include light sensors and air temperature and humidity sensors, which are installed inside the greenhouse to collect real-time data on the greenhouse's light intensity, air temperature, and humidity. The data is transmitted to the controller as the basis for switching between atomization and irrigation modes.

[0048] EC / pH sensors are installed in the storage tank 1 and the return line 15 to monitor the EC (conductivity) and pH of the nutrient solution in real time. The EC value is controlled within the range of 1.5-2.5 mS / cm, and the pH value is controlled within the range of 5.5-6.5. When the EC or pH value exceeds the set range, the controller automatically issues a command to replenish the nutrient solution or adjuster through the liquid addition device to ensure the stability of the nutrient solution concentration and pH.

[0049] The actuators include a low-pressure variable frequency pump 4, an ultrasonic atomizer 6, a three-way valve, a liquid level control valve 14, a return pump 19, etc. The controller controls the start and stop of the actuators and the operating parameters to achieve the switching of atomization mode and irrigation mode, as well as the precise control of pressure, liquid level, and nutrient solution parameters.

[0050] The system operates in three modes: atomization, root zone irrigation, and aeroponic-irrigation coupling. These modes automatically switch based on crop growth stages and environmental parameters, achieving low-pressure / pump-free energy-saving operation throughout. Specific controls include: Initialization phase: After the system starts, the controller first detects the liquid level in storage tank 1, the EC / pH value and temperature of the nutrient solution. If the liquid level is lower than the set value (e.g., 1 / 3 of the volume of storage tank 1), the controller will issue an alarm signal to remind the staff to add liquid. If the EC / pH value or temperature exceeds the set range, the controller will automatically adjust until the parameters meet the standards.

[0051] Atomization Mode: When the greenhouse air humidity is lower than the set value (e.g., 70%) and the light intensity is higher than the set value (e.g., 2000 lux), the controller starts the low-pressure variable frequency pump 4, and the energy storage and pressure stabilizing tank 5 stabilizes the pipeline pressure at 0.3-0.6 MPa. The nutrient solution is delivered to the self-cleaning nozzle 8 through the atomization pipeline 7 to achieve low-pressure atomization. For areas requiring precise atomization, such as the seedling area, the controller switches to the ultrasonic atomizer 6 to achieve pump-free atomization, further saving energy. During atomization, the rotating blades of the nozzle are automatically cleaned to prevent clogging; the pressure sensor monitors the pipeline pressure in real time and dynamically adjusts the variable frequency pump speed to ensure uniform atomization.

[0052] Root zone irrigation mode: When the soil moisture of the crop roots is lower than the set value (e.g., 60%), or when the crop is in the fruiting stage and needs a lot of water, the controller closes the valve of the atomizing pipeline 7 and opens the valve of the root zone irrigation pipeline 10. The low-pressure variable frequency pump 4 delivers the nutrient solution to the drip irrigation head 11 for precise drip irrigation of the root zone. The liquid level sensor in the collection tank 13 monitors the liquid level in real time and controls the return flow rate through the liquid level control valve 14 to ensure stable root zone moisture.

[0053] Aeroponics-Irrigation Coupling Mode: When crops are in their growth period and need to balance root respiration and water supply, the controller controls the atomization pipeline 7 and the irrigation pipeline to work simultaneously, adopting a "10 minutes of atomization plus 5 minutes of irrigation" cycle mode to achieve a smooth transition between aeroponics and irrigation and avoid sudden changes in the root zone environment; during the cycle, the returned nutrient solution is treated by the return purification module and then returned to the storage tank 1 to achieve a closed-loop cycle.

[0054] Emergency Handling: When the low-pressure variable frequency pump 4 malfunctions or loses power, the emergency liquid supply tank 9 automatically supplies liquid to the atomizing pipeline 7, and the controller sends an alarm signal at the same time; when the nozzle is blocked, the controller increases the pipeline pressure (briefly increasing it to 0.7MPa) to drive the self-cleaning nozzle 8 to rotate faster, achieving reverse self-cleaning. If the blockage is severe, the controller sends an alarm signal to remind the staff to handle it; when the microbial content in the nutrient solution exceeds the standard, the photocatalytic sterilizer 17 automatically extends the working time to ensure the disinfection effect.

[0055] The system was applied to a small greenhouse with an area of ​​50m². The system parameter configuration included: Nutrient solution storage and pretreatment module: storage tank 1 with a volume of 100L, pretreatment filter 2 with a 200-mesh stainless steel filter screen, magnetic descaling device 3 with a magnetic field strength of 0.3T, liquid level sensor with a range of 0-100cm, and temperature sensor with a range of 0-50℃.

[0056] Low-pressure / pumpless atomization module: Low-pressure variable frequency pump 4 rated pressure 0.3MPa, power 0.5kW; Energy storage and pressure stabilizing tank 5 volume 10L; Ultrasonic atomizer 6 frequency 20kHz, power 50W; Atomization pipeline 7 diameter 20mm; Self-cleaning nozzles 8 spaced 50cm, atomization angle 120°, atomized particle size 50-80μm; Emergency liquid supply tank 9 volume 50L.

[0057] Root zone circulating irrigation module: irrigation pipe diameter 20mm, drip head 11 flow rate 2L / h, one drip head 11 per crop; planting plate 12 tilt angle 5°, planting hole spacing 30cm; liquid collection tank 13 width 20cm, depth 10cm, guide slope 3°; liquid level control valve 14 rated flow rate 10L / h.

[0058] Reflux purification module: reflux pipeline 15, diameter 32mm; hydrocyclone 16, processing capacity 50L / h; photocatalytic sterilizer 17, UV-C lamp power 30W, TiO2 photocatalytic material coating thickness 0.1mm; ultrafiltration membrane filter 18, pore size 0.1μm, processing capacity 50L / h; return pump 19, power 0.3kW.

[0059] Intelligent control module: PLC controller model S7-200, light sensor range 0-10000 lux, air temperature and humidity sensor range 0-50℃, 0-100%RH; EC sensor range 0-5mS / cm, pH sensor range 4.0-8.0.

[0060] The specific installation steps for the system are as follows: Place the liquid storage tank 1 in a corner of the greenhouse, and connect it in sequence to the pretreatment filter 2 and the magnetized descaling device 3; install the low-pressure variable frequency pump 4 on the outlet pipe of the liquid storage tank 1, and connect it to the energy storage and pressure stabilizing tank 5, the atomizing pipe 7, and the irrigation pipe; lay the atomizing pipe 7 on the top of the greenhouse, and aim the self-cleaning nozzle 8 above the crop roots; install the planting board 12 above the liquid collection tank 13, and adjust the tilt angle to 5°; connect the return pipe 15 to the liquid collection tank 13 and the hydrocyclone 16, and connect it in sequence to the photocatalytic sterilizer 17, the ultrafiltration membrane filter 18, and the return pump 19, with the outlet of the return pump 19 connected to the liquid storage tank 1; connect all sensors and actuators to the PLC controller to complete the system assembly.

[0061] After the system starts up, the initial test shows that the liquid level in storage tank 1 is 60cm (set value 40cm), the EC value is 1.8mS / cm, the pH value is 6.0, and the temperature is 25℃. All parameters meet the standards.

[0062] When the greenhouse air humidity drops to 65% and the light intensity is 2500 lux, the controller starts the low-pressure variable frequency pump 4, the pipeline pressure stabilizes at 0.3 MPa, and the self-cleaning nozzle 8 starts atomizing. The atomization time is adjusted according to the humidity difference. The air humidity is checked every 10 minutes of atomization until the humidity reaches 70%, at which point atomization stops.

[0063] When the soil moisture around the crop roots drops to 55%, the controller switches to root zone irrigation mode, the drip irrigation head 11 starts supplying liquid, the irrigation flow rate is adjusted to 3L / h according to the soil moisture, the liquid level in the collection tank 13 is maintained at 6cm, and the excess nutrient solution is treated by the return purification module and returned to the storage tank 1 for recycling.

[0064] When the crop is in its growth period, the controller switches to coupling mode and adopts a cycle of "10 minutes of atomization plus 5 minutes of irrigation" to ensure a stable root zone environment.

[0065] Power outage test: After simulating a power outage, the emergency liquid supply tank 9 automatically supplied liquid for 3 hours, and the roots did not show signs of wilting due to water loss; Blockage test: After 300 hours of continuous operation, the nozzles were not blocked and the atomization effect was normal.

[0066] After one month of operation, the system energy consumption of this invention is reduced by 65% ​​compared to the traditional high-pressure coupling system; the nutrient solution utilization rate is increased to 92%; the nozzle clogging rate is 0%; the crop (lettuce) grows uniformly, the yield is increased by 15% compared to the traditional system, and the marketability is significantly improved; the system operates stably without failure, and the maintenance cost is reduced by 80%.

[0067] Therefore, this invention employs the aforementioned greenhouse aeroponics and root zone circulating irrigation coupling system, which consists of a closed-loop cycle composed of five modules: nutrient solution storage and pretreatment, low-pressure / pump-free atomization, root zone circulating irrigation, reflux purification, and intelligent control. The system adopts a low-pressure / pump-free design, and through modular structure, self-cleaning anti-clogging, and intelligent collaborative control, it achieves automatic switching between three modes and low-pressure energy-saving operation.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A coupled system for aeroponics and root zone circulating irrigation in a greenhouse, characterized in that, It includes a nutrient solution storage and pretreatment module, a low-pressure / pump-free atomization module, a root zone circulating irrigation module, a return purification module, and an intelligent control module. The low-pressure / pump-free atomization module and the root zone circulating irrigation module are connected in parallel to the main supply pipeline via a three-way valve. The return purification module is connected to both the root zone circulating irrigation module and the nutrient solution storage and pretreatment module. The low-pressure / pump-free atomization module includes a low-pressure variable frequency pump, an energy storage and stabilizing tank, an ultrasonic atomizer, an atomization pipeline, and self-cleaning nozzles. The energy storage and stabilizing tank is located between the low-pressure variable frequency pump and the atomization pipeline. The ultrasonic atomizer is connected in parallel with the atomization pipeline, and the self-cleaning nozzles are arranged at intervals along the atomization pipeline. The root zone circulating irrigation module includes root zone irrigation pipelines, drip irrigation heads, tiltable planting boards, a collection tank with a guide slope, and a liquid level control valve; the reflux purification module is equipped with a hydrocyclone, a photocatalytic sterilizer, and an ultrafiltration membrane filter in sequence; the intelligent control module is electrically connected to the low-pressure variable frequency pump, the energy storage and stabilizing tank, the ultrasonic atomizer, the three-way valve, the liquid level control valve, and the reflux purification module.

2. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The nutrient solution storage and pretreatment module includes a storage tank, a pretreatment filter, a magnetizing descaling device, a level sensor, and a temperature sensor. The pretreatment filter and the magnetizing descaling device are connected in series in the outlet pipeline of the storage tank. The level sensor and the temperature sensor are located inside the storage tank and are electrically connected to the intelligent control module.

3. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The low-pressure / pumpless atomization module is also equipped with an emergency liquid supply tank, which is connected in parallel with the atomization pipeline and relies on gravity to achieve emergency liquid supply.

4. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The self-cleaning nozzle has rotating blades inside and features a swirling spray structure.

5. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The tilt angle of the planting board is adjustable from 0 to 15°, the bottom slope of the liquid collection tank is 3 to 5°, and the liquid level control valve is located at the outlet of the liquid collection tank.

6. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The photocatalytic sterilizer uses a combination structure of UV-C lamp tube and TiO2 photocatalytic material, and the ultrafiltration membrane filter uses a hollow fiber membrane with a pore size of 0.1-0.2μm.

7. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The intelligent control module includes a PLC controller, environmental sensors, EC / pH sensors, and pressure sensors; the EC / pH sensors are located in the liquid storage tank and the return pipeline, respectively, and the pressure sensor is located inside the energy storage and pressure stabilizing tank.

8. The greenhouse aeroponics and root zone circulating irrigation coupling system according to claim 1, characterized in that, The coupling system adopts an alternating cycle of atomization and irrigation, with the atomization pipeline and irrigation pipeline operating synchronously and under control.

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