A root temperature intelligent control system for three-dimensional hydroponic crops and its implementation method

Abstract

The present invention provides an intelligent root temperature control system for three-dimensional hydroponic crops and a method for realizing the same, belonging to the field of greenhouse equipment and technology. Specifically, in the daytime, when the temperature in the greenhouse is higher than the root temperature T1 suitable for crop growth, the nutrient solution is added to the roots of the crops in the cultivation tank through the nutrient solution precise supply system and the root-targeted liquid supply pipe. At the same time, the heat source provides heat energy to the nutrient solution heating storage device and the phase change material heating storage device, and controls the temperature of the nutrient solution in the nutrient solution heating storage device to be T1. In the night time, when the temperature in the greenhouse is lower than T1, the control system adds the nutrient solution with a temperature of T1 in the nutrient solution heating storage device to the roots of the crops through the root-targeted liquid supply pipe. At the same time, by controlling the feeding amount of the liquid phase change material and relying on the latent heat of phase change of the material, the temperature of the nutrient solution at the roots of the crops in the cultivation tank is maintained at T1. The present invention can realize low-energy consumption, uniform, precise and efficient control of the root temperature of three-dimensional hydroponic crops.

Description

Technical Field

[0001] The present invention belongs to the field of greenhouse equipment and technology, and in particular relates to a root temperature intelligent control system for three-dimensional hydroponic crops and an implementation method thereof. Background Art

[0002] Hydroponics, also known as nutrient solution cultivation, refers to a facility-based soilless cultivation method in which the roots of crops grow directly in nutrient solution. It can adjust rhizosphere environmental conditions such as nutrients and temperature according to the needs of crop growth and development, and has a good foundation for intensive, clean, and intelligent production. However, the common three-dimensional hydroponic method represented by the A-frame has the problem of insufficient and uneven root temperature accumulation in winter, which greatly reduces the accumulation of crop nutrition and dry matter, resulting in the taste of crops being inferior to soil cultivation. High quality has seriously affected the market benefits of hydroponic crops and the rapid promotion of hydroponic technology.

[0003] Chinese patent (CN201110298064.0) proposed an electric three-dimensional cultivation rack, which can adjust the height of the cultivation trough to change the temperature-sensitive layer of the crop according to the temperature requirements of the crop in different growth periods, but the actual effect is not ideal, and the land utilization rate of the facility is greatly reduced. Chen Yifei proposed a crop root temperature control system that is suitable for soil cultivation and is composed of a drip irrigation pipe and a semiconductor heating wire in "Intelligent Control System for Three-Dimensional Cultivation of Strawberries in Solar Greenhouse", but the winter heat preservation of soil cultivation is much better than that of hydroponics, so this system is difficult to apply to hydroponic crops. Chinese patent (CN201620709747.9) proposed an automatic heating device for the roots of greenhouse plants, which achieves the goal of controlling the root temperature of the plant by controlling the temperature of the nutrient solution before supply and directly heating the substrate or culture solution in the cultivation trough with a heat-conducting pipe, but the energy consumption is high, and it cannot solve the problem of uneven liquid temperature caused by the length of the cultivation trough. In response to the high energy consumption problem of common greenhouse crop root automatic heating devices, a Chinese patent (CN110447436A) proposed a greenhouse cultivation rack based on low-temperature phase change material heat storage and auxiliary electric heating. The low-energy control of the air temperature around the crop can be achieved by combining phase change materials with a hot air circulation system. However, the rationality of this crop heating method is questionable, and the efficiency of heat transfer to the substrate or nutrient solution at the root of the crop is also very low. In summary, the existing greenhouse equipment and technology cannot effectively solve the problem of insufficient and uneven root temperature accumulation in winter faced by three-dimensional hydroponic crops. Summary of the invention

[0004] In view of the shortcomings in the prior art, the present invention provides a root temperature intelligent control system for three-dimensional hydroponic crops and an implementation method thereof, with low cost, high efficiency, uniformity and high quality as production goals, to achieve low-energy consumption, uniform, precise and efficient control of the root temperature of three-dimensional hydroponic crops throughout their entire growth cycle.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A method for realizing a root temperature intelligent control system for three-dimensional hydroponic crops comprises the following steps:

[0007] During the daytime, when the temperature in the greenhouse is higher than the root temperature T1 suitable for crop growth, the control system turns on the nutrient solution precision supply system to accurately mix the nutrient solution, and adds nutrient solution to the roots of the crops in the cultivation trough through the root-targeted liquid supply pipe; at the same time, the heat source provides heat energy to the nutrient solution heating storage device and the phase change material heating storage device, and the control system controls the nutrient solution temperature in the nutrient solution heating storage device to be the root temperature T1 suitable for crop growth, and obtains the liquid phase change material temperature T2 in the phase change material heating storage device;

[0008] During the night period, when the temperature in the greenhouse is lower than the root temperature T1 suitable for crop growth, the control system adds the nutrient solution with a temperature of T1 in the nutrient solution heating storage device to the crop roots through the root-to-target liquid supply pipe; the control system obtains the total heat loss nQ of the cultivation trough during n nutrient solution replacement cycles during the night period, and opens the feed control valve to control the feed amount of liquid phase change material to m.

[0009] Furthermore, when the space in the temperature control layer cannot meet the demand for the feed volume m, the control system obtains the temperature of the phase change material in the temperature control layer in real time. When its temperature is lower than the root temperature T1 suitable for crop growth, the solidified liquid phase change material is removed and the liquid phase change material is re-injected into the temperature control layer.

[0010] Furthermore, the total heat loss nQ of the cultivation tank during the n nutrient solution replacement cycles and the feed amount m satisfy:

[0011] nQ=mC(T2-T1)+mH

[0012] Where: C is the specific heat capacity of the phase change material, and H is the latent heat of phase change of the phase change material.

[0013] A root temperature intelligent control system for three-dimensional hydroponic crops, comprising:

[0014] The root liquid supply unit includes a nutrient solution precision supply system and a nutrient solution heating and storage device, wherein the nutrient solution precision supply system and the nutrient solution heating and storage device are opposite to the root of the crop through a root-targeted liquid supply pipe;

[0015] A liquid temperature control unit, comprising a heat insulation layer and a phase change material heating storage device, wherein the heat insulation layer is located outside the cultivation trough, and a temperature control layer is formed between the heat insulation layer and the outside of the cultivation trough, and the temperature control layer is connected to the phase change material heating storage device;

[0016] The control system controls the precise proportion of the nutrient solution in the nutrient solution precise supply system, the liquid temperature of the nutrient solution heating and storage device, and the opening and closing of the phase change material heating and storage device.

[0017] A first liquid supply control valve is arranged on the pipeline connecting the nutrient solution heating storage device and the root target liquid supply pipe, and the opening and closing of the first liquid supply control valve is controlled by the control system.

[0018] A second liquid supply control valve is provided on the pipeline connecting the nutrient solution precision supply system and the root target liquid supply pipe, and the opening and closing of the second liquid supply control valve is controlled by the control system.

[0019] A feed control valve is provided on the pipeline connecting the phase change material heating storage device and the temperature control layer, and the opening and closing of the feed control valve is controlled by a control system.

[0020] A temperature sensor is arranged inside the temperature control layer.

[0021] The nutrient solution heating storage device and the phase change material heating storage device are provided with heat energy by a heat source.

[0022] The crop cultivation trough is arranged on a three-dimensional cultivation frame.

[0023] The beneficial effects of the present invention are:

[0024] In the present invention, during the daytime, when the temperature in the greenhouse is higher than the root temperature T1 suitable for crop growth, nutrient solution is added to the roots of crops in the cultivation trough through the nutrient solution precision supply system and the root target liquid supply pipe. Since the temperature around the cultivation trough is relatively high, the environment with a relatively high temperature transfers heat to the nutrient solution with a relatively low liquid temperature, so that the temperature of the nutrient solution inside the cultivation trough gradually increases to the root temperature T1 suitable for crop growth; at the same time, the temperature in the greenhouse is relatively high, and the heat source converts the air energy and solar energy in the greenhouse into thermal energy, and provides thermal energy to the nutrient solution heating storage device and the phase change material heating storage device, so as to control the temperature of the nutrient solution in the nutrient solution heating storage device to be the root temperature T1 suitable for crop growth; during the nighttime, when the temperature in the greenhouse is lower than the root temperature T1 suitable for crop growth, The control system adds the nutrient solution with a temperature of T1 in the nutrient solution heating storage device to the root of the crop through the root-targeted liquid supply pipe; the control system obtains the total heat loss of the cultivation tank in n nutrient solution replacement cycles during the night time period, and opens the feed control valve to control the feed amount of the liquid phase change material; during the night time period, the heat loss of the nutrient solution in the cultivation tank is relatively fast, and the temperature of the nutrient solution provided by the nutrient solution heating storage device will gradually be lower than T1. When the liquid phase change material is injected into the temperature control layer, due to the existence of the heat insulation layer, the liquid phase change material will transfer heat energy to the nutrient solution in the cultivation tank alone, and the temperature of the nutrient solution in the cultivation tank will be increased to T1; at the same time, the liquid phase change material gradually solidifies, and its temperature drops to T1, and the temperature of the nutrient solution in the cultivation tank is maintained at T1 by relying on the material phase change latent heat. The present invention ensures that the temperature of the nutrient solution provided to the crop always maintains the optimal root temperature through the above-mentioned intelligent regulation, which is conducive to the healthy growth of the crop, and solves the problem of insufficient and uneven root temperature accumulation in winter faced by three-dimensional hydroponic crops at low cost and high efficiency, and achieves the production goal of homogeneous and high-quality hydroponic crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of the intelligent root temperature control system for three-dimensional hydroponic crops according to the present invention;

[0026] Figure 2 It is a schematic diagram of the principle of the liquid temperature control unit of the present invention.

[0027] In the figure: 1. heat source, 2. nutrient solution heating storage device, 3. first liquid supply control valve, 4. nutrient solution precision supply system, 5. second liquid supply control valve, 6. root target liquid supply pipe, 7. crop, 8. feeding control valve, 9. phase change material heating storage device, 10. three-dimensional cultivation rack, 11. control system, 12. thermal insulation layer, 13. temperature control layer, 14. temperature sensor. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited thereto. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0029] like Figure 1 As shown, a root temperature intelligent control system for three-dimensional hydroponic crops is composed of a three-dimensional cultivation frame 10, a root liquid supply unit, a liquid temperature control unit and a control system 11; the three-dimensional cultivation frame 10 is used to realize the hydroponic cultivation operation of crops 7 in the three-dimensional space of the greenhouse, and the root target liquid supply pipe 6 of the root liquid supply unit and the liquid temperature control unit are both installed on the three-dimensional cultivation frame 10.

[0030] like Figure 1 As shown, the root liquid supply unit includes a nutrient solution precision supply system 4 (Wang Yafang. Design and implementation of a fully automatic water-fertilizer integrated system [D]), a nutrient solution heating and storage device 2 (CN201920090615.6, a water-fertilizer integrated oxygenation and heating irrigation equipment dedicated to farmland), a plurality of root target liquid supply pipes 6, a first liquid supply control valve 3 and a second liquid supply control valve 5; the precise proportion of the nutrient solution of the nutrient solution precision supply system 4, the liquid temperature control of the nutrient solution heating and storage device 2, and the opening and closing of the first liquid supply control valve 3 and the second liquid supply control valve 5 are all realized by the control system 11. The root-targeted liquid supply pipe 6 is distributed corresponding to the position of the crop 7 in the cultivation trough on the three-dimensional cultivation frame 10, and the liquid outlet of each root-targeted liquid supply pipe 6 is aligned with the root position of each crop 7; the root-targeted liquid supply pipe 6 is respectively connected to the liquid supply pipelines of the nutrient solution precision supply system 4 and the nutrient solution heating and storage device 2, and a second liquid supply control valve 5 is provided on the pipeline connecting the nutrient solution precision supply system 4 and the root-targeted liquid supply pipe 6, and a first liquid supply control valve 3 is provided on the pipeline connecting the nutrient solution heating and storage device 2 and the root-targeted liquid supply pipe 6, and the opening and closing of the liquid supply pipeline are respectively controlled by the second liquid supply control valve 5 and the first liquid supply control valve 3.

[0031] like Figure 2As shown, the liquid temperature control unit includes a temperature control layer 13, a heat insulation layer 12, a phase change material, a phase change material heating storage device 9 (Wang Hongli. Research progress of phase change heat storage technology in greenhouses [J]) and a temperature sensor 14; the heat insulation layer 12 is located outside the crop cultivation tank, and a space is left between the heat insulation layer 12 and the outside of the cultivation tank to form a temperature control layer 13; a liquid phase change material filling port is provided on the upper edge of one side of the temperature control layer 13, the liquid phase change material filling port is connected to the phase change material heating storage device 9, and a feed control valve 8 is provided on the pipeline connecting the liquid phase change material filling port and the phase change material heating storage device 9, so that the feed control valve 8 controls the feed amount of the liquid phase change material in the temperature control layer 13, and the opening and closing of the feed control valve 8 is controlled by the control system 11. The temperature sensor 14 is located on both sides and the bottom of the temperature control layer 13, and the temperature data collected by the temperature sensor 14 is transmitted to the control system 11.

[0032] like Figure 1 As shown, the heat energy of the nutrient solution heating storage device 2 and the phase change material heating storage device 9 both comes from the heat source 1 (Ma Kunru. Comparison of heating performance of new solar energy / air energy direct expansion heat pump and air source heat pump [J]), and the heat source 1 converts the air energy and solar energy in the greenhouse into heat energy.

[0033] A method for realizing a root temperature intelligent control system for three-dimensional hydroponic crops, specifically comprising the following steps:

[0034] Step (1), according to agronomic requirements, determine the optimal root temperature of hydroponic crops in a specific growth cycle as T1; measure the heat loss Q of the nutrient solution in a nutrient solution replacement cycle of the cultivation tank; based on the above conditions, obtain a phase change material that meets the optimal root temperature T1 and the heat loss Q of the nutrient solution, and its phase change temperature is T1, specific heat capacity is C, and phase change latent heat is H; place the determined phase change material in a phase change material heating storage device 9;

[0035] Step (2), during the daytime, when the temperature in the greenhouse (obtained in real time by a temperature sensor disposed in the greenhouse and transmitted to the control system 11) is higher than T1, the control system 11 turns on the nutrient solution precision supply system 4 to accurately mix the nutrient solution, and controls the second liquid supply control valve 5 to open, and adds nutrient solution to the root position of the crop 7 in the cultivation trough through the root-targeted liquid supply pipe 6; at the same time, the control system 11 turns on the heat source 1 to convert the air energy and solar energy in the greenhouse into heat energy, and provides heat energy to the nutrient solution heating storage device 2 and the phase change material heating storage device 9. The control system 11 ensures that the nutrient solution temperature in the nutrient solution heating storage device 2 is T1 by controlling the opening and closing of the heat source 1, and obtains the temperature T2 of the liquid phase change material in the phase change material heating storage device 9 (T1 and T2 are obtained by the temperature sensors disposed inside the nutrient solution heating storage device 2 and the phase change material heating storage device 9, respectively);

[0036] Step (3), during the night, when the temperature in the greenhouse is lower than T1, the control system 11 controls the second liquid supply control valve 5 to close and the first liquid supply control valve 3 to open, and the nutrient solution at a temperature of T1 in the nutrient solution heating storage device 2 is added to the root position of the crop 7 in the cultivation tank through the root-targeting liquid supply pipe 6;

[0037] Step (4), at the same time, the control system 11 obtains the total heat loss of the cultivation tank in n nutrient solution replacement cycles during the night time period as nQ, and opens the feed control valve 8 to control the feed amount of the liquid phase change material in the temperature control layer 13 to be m. The total heat loss of the cultivation tank and the feed amount satisfy the following relationship: nQ=mC(T2-T1)+mH; during the night time period, the heat loss of the nutrient solution in the cultivation tank is relatively fast, and the temperature of the nutrient solution provided by the nutrient solution heating and storage device 2 will gradually be lower than T1. When the liquid phase change material is injected into the temperature control layer 13, due to the existence of the heat insulation layer 12, the liquid phase change material will transfer heat energy to the nutrient solution in the cultivation tank alone, and the temperature of the nutrient solution in the cultivation tank will be increased to T1; at the same time, the liquid phase change material gradually solidifies, and its temperature drops to T1, and relying on the material phase change latent heat, the temperature of the nutrient solution in the cultivation tank is maintained at T1;

[0038] Step (5), when the space of the temperature control layer 13 cannot meet the demand of the feed amount m, the control system 11 obtains the temperature of the phase change material in the temperature control layer 13 in real time through the temperature sensor 14. When its temperature is lower than T1, an early warning signal is issued, the thermal insulation layer 12 is manually and quickly disassembled, and the solidified liquid phase change material m1 is removed, the temperature control layer 13 is emptied, and the operation of step (4) is repeated, and the liquid phase change material is re-injected, and the amount is m-m1. In this way, the root temperature of three-dimensional hydroponic crops throughout the growth cycle is accurately and efficiently controlled at low cost and high efficiency.

[0039] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A method for realizing a root temperature intelligent control system for three-dimensional hydroponic crops, characterized in that: The steps include: During the daytime, when the temperature in the greenhouse is higher than the root temperature T1 suitable for crop growth, the control system (11) turns on the nutrient solution precision supply system (4) to accurately mix the nutrient solution, and adds nutrient solution to the roots of the crops (7) in the cultivation trough through the root-targeted liquid supply pipe (6); at the same time, the heat source (1) provides heat energy to the nutrient solution heating storage device (2) and the phase change material heating storage device (9), and the control system (11) controls the nutrient solution temperature in the nutrient solution heating storage device (2) to be the root temperature T1 suitable for crop growth, and obtains the liquid phase change material temperature T2 in the phase change material heating storage device (9); During the night time period, when the temperature in the greenhouse is lower than the root temperature T1 suitable for crop growth, the control system (11) adds the nutrient solution at the temperature T1 in the nutrient solution heating storage device (2) to the root of the crop (7) through the root-targeted liquid supply pipe (6); the control system (11) obtains the total heat loss nQ of the cultivation tank during n nutrient solution replacement cycles during the night time period, and opens the feed control valve (8) to control the feed amount of the liquid phase change material to m; When the space of the temperature control layer (13) cannot meet the demand of the feed amount m, the control system (11) obtains the temperature of the phase change material in the temperature control layer (13) in real time. When the temperature is lower than the root temperature T1 suitable for crop growth, the solidified liquid phase change material is removed and the liquid phase change material is re-injected into the temperature control layer (13); The total heat loss nQ of the cultivation tank during the n nutrient solution replacement cycles and the feed amount m satisfy: nQ=mC(T2-T1)+mH Where: C is the specific heat capacity of the phase change material, and H is the latent heat of phase change of the phase change material.

2. A root temperature intelligent control system for three-dimensional hydroponic crops according to the root temperature intelligent control system implementation method of claim 1, characterized in that: include: The root liquid supply unit comprises a nutrient solution precision supply system (4) and a nutrient solution heating and storage device (2), wherein the nutrient solution precision supply system (4) and the nutrient solution heating and storage device (2) are opposite to the roots of the crop (7) via a root target liquid supply pipe (6); A liquid temperature control unit, comprising a heat insulation layer (12) and a phase change material heating storage device (9), wherein the heat insulation layer (12) is located outside the crop cultivation trough, and a temperature control layer (13) is formed between the heat insulation layer (12) and the outside of the crop cultivation trough, and the temperature control layer (13) is connected to the phase change material heating storage device (9); The control system (11) controls the precise proportion of the nutrient solution of the precise nutrient solution supply system (4), the liquid temperature of the nutrient solution heating and storage device (2), and the opening and closing of the phase change material heating and storage device (9).

3. The root temperature intelligent control system of three-dimensional hydroponic crops according to claim 2 is characterized in that: A first liquid supply control valve (3) is provided on a pipeline connecting the nutrient solution heating storage device (2) and the root target liquid supply pipe (6), and the opening and closing of the first liquid supply control valve (3) is controlled by a control system (11).

4. The root temperature intelligent control system of three-dimensional hydroponic crops according to claim 2 is characterized in that: A second liquid supply control valve (5) is provided on the pipeline connecting the nutrient solution precision supply system (4) and the root target liquid supply pipe (6), and the opening and closing of the second liquid supply control valve (5) is controlled by a control system (11).

5. The root temperature intelligent control system of three-dimensional hydroponic crops according to claim 2 is characterized in that: A feed control valve (8) is provided on the pipeline connecting the phase change material heating storage device (9) and the temperature control layer (13), and the opening and closing of the feed control valve (8) is controlled by a control system (11).

6. The root temperature intelligent control system of three-dimensional hydroponic crops according to claim 2 is characterized in that: A temperature sensor (14) is provided inside the temperature control layer (13).

7. The root temperature intelligent control system of three-dimensional hydroponic crops according to claim 2 is characterized in that: The nutrient solution heating storage device (2) and the phase change material heating storage device (9) are provided with thermal energy by the heat source (1).

8. The root temperature intelligent control system of three-dimensional hydroponic crops according to claim 2 is characterized in that: The crop cultivation trough is arranged on a three-dimensional cultivation frame (10).

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