Nutrient solution concentration detection method and device based on soilless culture

Abstract

The invention relates to a nutrient solution concentration detection method and device based on soilless culture, and the detection method comprises the following steps: S1, arranging a first magnet and a second magnet on two opposite side surfaces of a main body, and determining the magnetic field intensity B; a first electrode and a second electrode are arranged on the other two opposite side faces of the main body, and the electric field intensity E is determined; s2, a pressure sensing device is fixed in the main body, and the distance L between the pressure sensing device and the inlet is measured; s3, determining ion charge e and ion mobility mu according to the type of the nutrient solution; s4, the numerical value P of the pressure sensing device is detected, data are substituted into a formula to calculate the ion concentration n of the nutrient solution, the detection precision is high, and the cost is low.

Description

Technical Field

[0001] This invention relates to the field of nutrient solution concentration detection, and in particular to a method and apparatus for detecting nutrient solution concentration for hydroponics. Background Technology

[0002] Soilless cultivation refers to a planting method that uses a non-soil medium to fix the plants. Soilless cultivation usually uses nutrient solution to provide nutrients for the plants, so real-time monitoring of the nutrient solution concentration is crucial for plant growth.

[0003] Traditional methods for measuring nutrient solution concentration typically involve measuring the conductivity (EC) of the nutrient solution using a conductivity meter, and then calculating the concentration. Specifically, a probe is inserted into the nutrient solution with a voltage applied, and the current between the probe electrodes is measured. This current is then converted to conductivity, and finally, the nutrient solution concentration is calculated. However, this method is highly susceptible to external environmental interference; for example, different temperatures significantly affect conductivity. To improve accuracy, advanced temperature compensation algorithms, complex waveform generation circuits, and high-speed conversion circuits are often required. Furthermore, the probes used are expensive, have short lifespans, and limited practicality. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for detecting the concentration of nutrient solution in soilless cultivation. The method and apparatus for detecting the concentration of nutrient solution in soilless cultivation have the characteristics of high accuracy and low cost, and have good applicability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for detecting the concentration of nutrient solution used in hydroponics includes the following steps: S1, a first magnet and a second magnet are set on two opposite sides of the main body, and the magnetic field strength B is determined; a first electrode and a second electrode are set on the other two opposite sides of the main body, and the electric field strength E is determined. S2, fix a pressure sensing device inside the main body, and measure the distance L between the pressure sensing device and the inlet; S3, determine the ionic charge e and ionic mobility μ according to the type of nutrient solution; S4, detect the value P of the pressure sensing device and substitute the data into the formula. Calculate the ion concentration n of the nutrient solution.

[0006] Preferably, in step S1, one end of the first magnet, the second magnet, the first electrode, and the second electrode is flush with the inlet, and the length of the first magnet, the second magnet, the first electrode, and the second electrode is greater than or equal to the distance L from the inlet to the pressure sensing device.

[0007] A nutrient solution concentration detection device for hydroponics includes: a main body having an inlet and an outlet; The first magnet and the second magnet are arranged at intervals on opposite sides of the inlet; The first electrode and the second electrode are spaced apart and located on opposite sides of the inlet. The arrangement direction of the first magnet and the second magnet is perpendicular to the arrangement direction of the first electrode and the second electrode. The direction of the Lorentz force formed by the first magnet, the second magnet, the first electrode, and the second electrode is parallel to the direction from the inlet toward the outlet. A pressure sensing device is disposed within the main body.

[0008] Preferably, the pressure sensing device includes a pressure sensor, a guide fluid, and a bracket. The guide fluid is fixed to the pressure sensor, the pressure sensor is positioned facing the inlet, and the diameter of the guide fluid gradually decreases along the direction away from the inlet. One end of the bracket is fixed to the guide fluid.

[0009] Preferably, it further includes a blade fixedly disposed within the main body, and the pressure sensing device is disposed on the side of the blade facing the inlet.

[0010] Preferably, the first magnet and the second magnet are fixedly disposed on the outer side of the main body, and the first electrode and the second electrode are fixedly disposed on the inner wall surface of the main body.

[0011] Preferably, it further includes a control component, which is electrically connected to the first electrode, the second electrode, and the pressure sensing device.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The above-mentioned technical solution provides a method for detecting the concentration of nutrient solution for hydroponics. By energizing the first and second electrodes, and in conjunction with the first and second magnets, a Lorentz force is generated. The Lorentz force propels the nutrient solution to move. The nutrient solution with a certain speed acts on the pressure sensing device, which can detect the pressure value. Based on the pressure value, the ion concentration of the nutrient solution can be calculated using a formula. The method has high detection accuracy and low cost. Attached Figure Description

[0013] Figure 1 A front view of a nutrient solution concentration detection device for hydroponics provided in an embodiment of the present invention; Figure 2 A schematic diagram of the back of a nutrient solution concentration detection device for soilless cultivation provided in an embodiment of the present invention; Figure 3A schematic diagram of a pressure sensing device provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the Lorentz force.

[0014] 1. Main body; 11. Inlet; 12. Outlet; 2. First magnet; 3. Second magnet; 4. First electrode; 5. Second electrode; 6. Blade; 7. Pressure sensing device; 71. Pressure sensor; 72. Fluid guide; 73. Support. Detailed Implementation

[0015] The present invention will now be described in more detail with reference to the accompanying drawings. It should be noted that the following description of the present invention with reference to the accompanying drawings is merely illustrative and not restrictive. Various different embodiments can be combined with each other to form other embodiments not shown in the following description.

[0016] Please see Figures 1 to 4 This invention provides a method and apparatus for detecting the concentration of nutrient solution used in hydroponics, wherein the method for detecting the concentration of nutrient solution includes the following steps: S1, a first magnet 2 and a second magnet 3 are set on two opposite sides of the main body 1, and the magnetic field strength B is determined; a first electrode 4 and a second electrode 5 are set on the other two opposite sides of the main body 1, and the electric field strength E is determined. S2, fix the pressure sensing device 7 inside the main body 1, and measure the distance L between the pressure sensing device 7 and the inlet 11; S3, determine the ionic charge e and ionic mobility μ according to the type of nutrient solution; S4, detect the value P of pressure sensor 7 and substitute the data into the formula. Calculate the ion concentration n of the nutrient solution.

[0017] The derivation process of the relationship between ion concentration and pressure sensor values: An electric field E is generated by energizing the first electrode 4 and the second electrode 5, and a magnetic field B is generated between the first magnet 2 and the second magnet 3. At this time, the charged ions in the nutrient solution are subjected to a Lorentz force f in the electric field E and the magnetic field B. The force density (force per unit volume) is: f = ρE + JB. Where ρ is the charge density and J is the current density.

[0018] In addition, the nutrient solution is an electrolyte solution, which is generally electrically neutral, that is, the net charge density ρ is zero. Therefore, the magnitude of the Lorentz force f is mainly J×B.

[0019] The current density J is related to the conductivity σ, i.e., J = σE. Therefore, when the electric field E and the magnetic field B are perpendicular to each other, the magnitude of the Lorentz force f is: f = σEB.

[0020] The conductivity σ of the nutrient solution is directly proportional to the ion concentration n, i.e., σ = neμ, where e is the ion charge and μ is the ion mobility, which is related to the ion type and the properties of the nutrient solution.

[0021] The Lorentz force f propels the nutrient solution forward. Let the acceleration distance of the nutrient solution be L, and its velocity be v. According to the law of conservation of energy, the kinetic energy per unit volume comes from the work done by the Lorentz force, i.e.: fL = ½ρ m v 2 , where ρ m The mass density of the nutrient solution can be obtained by measurement and is a constant.

[0022] Therefore, when the nutrient solution collides with the pressure sensor, the pressure P (force per unit area) detected by the pressure sensor is related to the kinetic energy flow rate of the fluid, i.e.: P = ρ m v 2 Combining the above equation, v can be eliminated. 2 We obtain P = 2fL. Substituting f = σEB and σ = neμ, we can obtain the relationship between the pressure sensor and the ion concentration as: P = 2neμEBL.

[0023] Therefore, it can be concluded that the ion concentration n is directly proportional to the pressure sensor value P, that is... Where e is the ionic charge, which depends on the ion type. The staff can know which ions are present in the nutrient solution, so e is a known constant value. μ is the ion mobility, which depends on the temperature, viscosity of the nutrient solution, etc. The staff can know the type of nutrient solution to obtain the viscosity, as well as the temperature during the test, so μ is a known constant value. E is the electric field strength, which depends on the voltage and distance between the first electrode 4 and the second electrode 5. B is the magnetic field strength, which depends on the performance 3 of the first magnet 2 and the second magnet. L is the acceleration distance of the nutrient solution, that is, the straight-line distance from the inlet 11 to the pressure sensing device 7.

[0024] The nutrient solution concentration detection device provided by the present invention includes a main body 1, a first magnet 2, a second magnet 3, a first electrode 4, a second electrode 5, a blade 6, and a pressure sensing device 7.

[0025] Specifically, the main body 1 has an inlet 11 and an outlet 12; a first magnet 2 and a second magnet 3 are spaced apart and located on opposite sides of the inlet 11; a first electrode 4 and a second electrode 5 are spaced apart and located on the other opposite sides of the inlet 11, the arrangement direction of the first magnet 2 and the second magnet 3 is perpendicular to the arrangement direction of the first electrode 4 and the second electrode 5, and the direction of the Lorentz force formed by the first magnet 2, the second magnet 3, the first electrode 4, and the second electrode 5 is parallel to the direction from the inlet 11 toward the outlet 12; a pressure sensing device 7 is disposed inside the main body 1.

[0026] The main body 1 can be rectangular in shape and hollow inside, thus forming an inlet 11 and an outlet 12. Nutrient solution, under the influence of the Lorentz force, can enter the main body 1 through the inlet 11 and exit through the outlet 12. The main body 1 has two sets of opposing sidewalls. A first magnet 2 and a second magnet 3 are fixedly mounted on the outer surface of one set of sidewalls, while a first electrode 4 and a second electrode 5 are fixedly mounted on the inner surface of the other set of sidewalls.

[0027] The blade 6 is fixedly installed inside the main body 1, and the blade 6 is located on the side closer to the outlet 12. A pressure sensing device 7 is fixedly installed on the side of the blade 6 facing the inlet 11.

[0028] It is important to note that one end of the first magnet 2, the second magnet 3, the first electrode 4, and the second electrode 5 can be flush with the inlet 11, thus ensuring that the nutrient solution is subjected to the Lorentz force immediately after entering the inlet 11. The other ends of the first magnet 2, the second magnet 3, the first electrode 4, and the second electrode 5 extend towards the outlet 12, and the length of the first magnet 2, the second magnet 3, the first electrode 4, and the second electrode 5 must be at least greater than or equal to the straight-line distance from the inlet 11 to the pressure sensing device 7, thereby ensuring that the nutrient solution is continuously subjected to the Lorentz force before acting on the pressure sensing device 7.

[0029] It should be clear that in order to detect changes in the conductivity (EC) of the nutrient solution, this application keeps all other variables fixed, such as voltage, magnetic field strength, surface area and spacing of the first electrode 4 and the second electrode 5, and the position and size of the first magnet 2 and the second magnet 3. The experimental data show that the pressure detected by the pressure sensor 71 is basically linearly related to the concentration of the nutrient solution.

[0030] More specifically, the distance between the first electrode 4 and the second electrode 5, and the distance between the first magnet 2 and the second magnet 3 are both 3cm, while the length of the first electrode 4 and the second electrode 5 is 10cm.

[0031] The pressure sensing device 7 includes a pressure sensor 71, a guide fluid 72, and a bracket 73. The guide fluid 72 is fixed to the pressure sensor 71, which is positioned towards the inlet 11. The diameter of the guide fluid 72 gradually decreases along the direction away from the inlet 11, thus providing a stabilizing effect. One end of the bracket 73 is fixed to the guide fluid 72, and the tip of the bracket 73 away from the guide fluid 72 can act on a secondary pressure sensor, correcting the pressure reading at low pressure.

[0032] In addition, the nutrient solution concentration detection device may also include a control component, which is electrically connected to the first electrode 4, the second electrode 5, and the pressure sensing device 7. Specifically, it may be electrically connected to control the opening and closing of the current of the first electrode 4 and the second electrode 5, as well as to transmit the signal of the pressure sensing device 7.

[0033] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for detecting the concentration of nutrient solution used in hydroponics, characterized in that, Includes the following steps: S1, a first magnet (2) and a second magnet (3) are set on two opposite sides of the main body (1), and the magnetic field strength B is determined; a first electrode (4) and a second electrode (5) are set on the other two opposite sides of the main body (1), and the electric field strength E is determined; S2, fix the pressure sensing device (7) inside the main body (1) and measure the distance L between the pressure sensing device (7) and the inlet (11); S3, determine the ionic charge e and ionic mobility μ according to the type of nutrient solution; S4, detect the value P of the pressure sensing device (7) and substitute the data into the formula. Calculate the ion concentration n of the nutrient solution.

2. The method for detecting nutrient solution concentration for hydroponics as described in claim 1, characterized in that, In step S1, one end of the first magnet (2), the second magnet (3), the first electrode (4), and the second electrode (5) are flush with the inlet (11), and the length of the first magnet (2), the second magnet (3), the first electrode (4), and the second electrode (5) is greater than or equal to the distance L from the inlet (11) to the pressure sensing device (7).

3. A nutrient solution concentration detection device for hydroponics, used in the nutrient solution concentration detection method for hydroponics as described in any one of claims 1-2, characterized in that, include: The main body (1) has imports (11) and exports (12); The first magnet (2) and the second magnet (3) are spaced apart and located on opposite sides of the inlet (11); The first electrode (4) and the second electrode (5) are spaced apart and located on the other two sides opposite to the inlet (11). The arrangement direction of the first magnet (2) and the second magnet (3) is perpendicular to the arrangement direction of the first electrode (4) and the second electrode (5). The direction of the Lorentz force formed by the first magnet (2), the second magnet (3), the first electrode (4), and the second electrode (5) is parallel to the direction of the inlet (11) toward the outlet (12). A pressure sensing device (7) is disposed within the main body (1).

4. The nutrient solution concentration detection device for hydroponics as described in claim 3, characterized in that, The pressure sensing device (7) includes a pressure sensor (71), a guide fluid (72), and a bracket (73). The guide fluid (72) is fixed to the pressure sensor (71). The pressure sensor (71) is positioned facing the inlet (11), and the diameter of the guide fluid (72) gradually decreases along the direction away from the inlet (11). One end of the bracket (73) is fixed to the guide fluid (72).

5. The nutrient solution concentration detection device for hydroponics as described in claim 3, characterized in that, It also includes a blade (6) fixedly installed in the main body (1), and the pressure sensing device (7) is installed on the side of the blade (6) facing the inlet (11).

6. The nutrient solution concentration detection device for hydroponics as described in claim 3, characterized in that, The first magnet (2) and the second magnet (3) are fixedly disposed on the outer side of the main body (1), and the first electrode (4) and the second electrode (5) are fixedly disposed on the inner wall surface of the main body (1).

7. The nutrient solution concentration detection device for hydroponics as described in claim 3, characterized in that, It also includes a control unit, which is electrically connected to the first electrode (4), the second electrode (5), and the pressure sensing device (7).

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