An active regulation system and method for increasing temperature and air in a greenhouse

Abstract

The application discloses a kind of active control system and method for greenhouse cold-proof, heating and gas increasing, which belongs to the field of facility agriculture engineering.The active control system for greenhouse soil marginal cold-proof, heating and indoor gas increasing is mainly composed of cold-proof pipe groove, ventilation pipe, variable frequency fan, temperature sensor, CO2 concentration sensor and automatic control device, wherein the cold-proof pipe is buried in the low-temperature marginal place of greenhouse below the ground surface, and the pipe groove under the cold-proof pipe is filled with straw; CO2 produced by straw fermentation enters the upper pipe groove through the perforated partition plate to increase the supply of CO2 in the room; the heat generated by fermentation is transmitted to the surrounding soil through the lower pipe groove for storage, and the air circulation inside and outside the pipeline transmits the heat energy in the indoor air during the day to the soil through the upper pipe groove, thereby jointly playing the role of active cold-proof and heating.The application realizes the purpose of active cold-proof, heating of greenhouse marginal soil and indoor CO2 increasing by coupling heat circulation in the greenhouse with straw fermentation reaction, and has the characteristics of energy saving, low carbon, ecological protection, economic efficiency and high efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of facility agricultural engineering, and particularly relates to an active regulation system and method for cold prevention and temperature and gas increase in a greenhouse. BACKGROUND

[0002] In horticultural facilities such as greenhouses and sheds, there is a common problem of excessively low soil temperature at the periphery in winter and insufficient CO2 concentration in the greenhouse, which is not conducive to crop growth and leads to unsatisfactory yield and quality in winter production. To solve this problem of soil marginal effect, passive measures such as adding foundation insulation or setting cold prevention trenches are usually used in the design, but the investment cost is high, the adjustability is poor, and the effect is not ideal. At the same time, the solar radiation heat energy incident into the greenhouse during the day is absorbed by crops, soil, and walls, and the remaining heat energy enters the greenhouse air, resulting in high temperature in the greenhouse during the day. Therefore, ventilation measures are often needed to discharge it to the outside, which is undoubtedly a waste of energy. The ground heat exchange technology can store the excess heat in the greenhouse during the day in the soil for air heating at night, but the soil marginal effect problem has not been addressed in traditional applications. In terms of CO2 supplementation in greenhouses, there is no other economic and effective technical measure except for ventilation to introduce outdoor air. In some production practices, straw fermentation technology has been tried to fill straw into the roots of crops, which can increase the temperature and gas in the greenhouse, and the fermented straw can be directly returned to the field, but it also lacks active regulation, and can only be filled once every cultivation period, which cannot match the growth process well, and has great limitations. In addition, the soil temperature in the greenhouse is low in winter, and the reaction process and rate of the straw filled in the soil will be affected without an external heat source, so it is difficult to control the time and rate of straw fermentation and gas production, which makes it more difficult to match the cultivation demand. To solve the above problems, the present application provides a technical solution for active regulation to realize energy saving, low carbon, and green, and to solve the problems of soil marginal cold prevention and temperature increase and CO2 supplementation in the greenhouse. SUMMARY

[0003] The application aims to provide an active control system and method for cold prevention, temperature increase and air increase in a greenhouse. The active control system for cold prevention, temperature increase and air increase in the greenhouse mainly comprises a cold prevention pipe groove, a ventilation pipe, a variable frequency fan, a temperature sensor, a CO2 concentration sensor and an automatic control device. The cold prevention pipe groove is installed below the soil surface at the edge of the greenhouse. The cold prevention pipe groove is assembled by a lower pipe groove 1, a middle hole partition plate 2 and an upper pipe groove 3. The hole partition plate 2 is arranged between the lower pipe groove 1 and the upper pipe groove 3. The ventilation pipe comprises an air inlet pipe 4 and an air outlet pipe 5. The air inlet pipe 4 is installed at both ends of the upper pipe groove 3, and the air outlet pipe 5 is installed at the middle of the upper pipe groove 3. The variable frequency fan 6 for ventilation control is arranged in the ventilation pipe. The lower pipe groove 1 is used for filling straws. The soil temperature sensor 9, the indoor air temperature sensor 10 and the CO2 concentration sensor 11 are installed at appropriate positions in the greenhouse. The automatic control device 12 in the greenhouse is connected with the variable frequency fan 6, the soil temperature sensor 9, the indoor air temperature sensor 10 and the CO2 concentration sensor 11 respectively. The opening and air volume of the variable frequency fan 6 are controlled according to the temperature parameters and the CO2 concentration detected by the sensors.

[0004] The lower pipe groove 1 is a semicircular, arc-shaped or square pipe groove. The groove opening faces upward during use. The lower pipe groove 1 is mainly used for carrying straws and serving as a container for straw fermentation. The lower pipe groove 1 can be made of PVC, cement or concrete materials with good moisture resistance, corrosion resistance and heat conductivity.

[0005] The hole partition plate 2 is mainly used for separating the lower pipe groove 1 and the upper pipe groove 3. The hole partition plate 2 is provided with uniformly distributed air holes with a diameter of 1 cm. The air holes can prevent the soil or straws from being blocked and can timely transmit the CO2 gas generated by the straw fermentation in the lower pipe groove 1 to the upper pipe groove 3.

[0006] The upper pipe groove 3 is a semicircular or arc-shaped pipe groove. The groove opening faces downward during use and is arranged on the lower pipe groove 1. The air convection space is formed between the lower pipe groove 1 and the upper pipe groove 3 by the hole partition plate 2. The upper pipe groove 3 can be made of PVC, cement or concrete materials with good moisture resistance, corrosion resistance and heat conductivity.

[0007] The air inlet pipe 4 and the air outlet pipe 5 are installed on the upper pipe groove 3. The air inlet pipe 4 and the air outlet pipe 5 are inserted into the upper pipe groove 3 through the local holes of the upper pipe groove 3 and are connected and fixed by the L-shaped joint 7 and the T-shaped joint 8 arranged on the upper pipe groove 3.

[0008] The air inlet pipe 4 is arranged at a height of 0.5 m from the ground to prevent the soil and sundries from falling into the pipe and being blocked. The air outlet pipe 5 is arranged at a height of 1.0 m from the ground to facilitate the discharge of the air rich in CO2 to the crop canopy height. The pipe material can be selected from PVC materials with light weight and good durability.

[0009] The variable frequency fan 6 is installed at the bottom of the air outlet pipe 5 and is used for forced convection of the air in and out of the pipe.

[0010] The soil temperature sensor 9 is installed in the soil near the wall of the upper pipe groove 3, and the air temperature sensor 10 is installed in the crop canopy height range.

[0011] The CO2 concentration sensor 11 is installed in the upper pipe groove 3 and the indoor crop canopy height range, respectively, for detecting the CO2 concentration in the upper pipe groove 3 and the CO2 concentration in the indoor air, respectively.

[0012] The cold-proof pipe is buried below the ground surface at the low-temperature margin of the greenhouse according to the facility form and requirements. The CO2 generated by straw fermentation enters the upper pipe groove 3 through the partition 2. The fermentation heat can be transmitted to the surrounding soil through the wall of the lower pipe groove 1 under the action of temperature difference, and the temperature of the deep margin soil of the greenhouse is raised to achieve the purpose of active cold-proof and warming. The variable frequency fan 6 can realize air convection circulation between the greenhouse and the upper pipe groove 3. During the day, the excess heat in the indoor high-temperature air can be taken to the underground. Under the action of temperature difference, most of the heat will be transmitted to the surrounding soil through the heat transfer of the wall of the upper pipe groove 3, raising the temperature of the shallow margin soil of the greenhouse and achieving the effect of active cold-proof and warming. At the same time, during the early stage of straw fermentation, the temperature of the straw is relatively low. Under the action of temperature difference, part of the heat will also be transmitted downward to the straw, playing a role in promoting straw fermentation.

[0013] An active regulation method for a greenhouse soil margin cold-proof and warming and indoor air increase active regulation system is characterized in that a cold-proof pipe groove is arranged below the ground surface at the low-temperature soil margin in the greenhouse, straw is placed in the pipe groove, and CO2 gas and heat are generated by straw fermentation. The CO2 gas is transmitted to the indoor air through the pipeline system, and the generated heat is mainly transmitted to the surrounding soil through the pipe wall, thereby achieving the purpose of soil margin cold-proof and indoor air increase. In addition, with the circulation and exchange between the air in the pipe and the indoor air, the excess heat in the greenhouse during the day enters the upper pipe groove, which also transmits to the surrounding soil through the pipe wall under the action of temperature difference, further enhancing the cold-proof and warming effect of the system on the margin soil of the greenhouse. The active regulation system actively regulates, and the active regulation method is implemented as follows:

[0014] (1) The cold-proof pipe groove is buried below the ground surface at a position with lower surrounding soil temperature in the greenhouse, the lower pipe groove 1 is filled with straw, the air inlet pipe 4 is installed at both ends of the upper pipe groove 3, the air outlet pipe 5 is installed at the middle of the upper pipe groove 3, and the variable frequency fan 6 is built-in ventilation control. The cold-proof pipe groove not only insulates the direct heat transfer between the inside and outside of the surrounding soil, but also plays a role in heat preservation and cold-proof. At the same time, the upper pipe groove 3 can realize heat exchange and CO2 transmission between the greenhouse and the upper pipe groove 3 through the forced convection of the variable frequency fan 6.

[0015] (2) The CO2 gas generated by the straw fermentation in the lower pipe tank 1 can diffuse to the space of the upper pipe tank 3 through the perforated partition 2. The heat generated by the straw fermentation in the lower pipe tank 1 can be transmitted to the surrounding soil under the action of the temperature difference between the inside and outside of the pipe wall, thereby increasing the temperature of the surrounding soil and achieving the effect of deep soil cold prevention and temperature increase;

[0016] (3) The temperature sensor detects the temperature of the soil around the pipe wall of the upper pipe tank 3 and the space temperature of the crop canopy height in the indoor space. The CO2 concentration sensor 11 detects the CO2 concentration of the crop canopy height in the upper pipe tank 3 and the greenhouse air, and transmits them to the automatic control device 12. The automatic control device 12 automatically controls according to the target control parameters obtained by the above detection.

[0017] (4) Under the forced convection of the variable frequency fan 6 during the day, the indoor high-temperature air can be introduced into the upper pipe tank 3. Under the action of the temperature difference between the inside and outside of the pipe wall, it is stored in the surrounding soil, thereby increasing the temperature of the surrounding soil and achieving the purpose of shallow soil cold prevention and temperature increase.

[0018] (5) Under the forced convection of the variable frequency fan 6 during the day, the high-concentration CO2 contained in the convection exchange between the upper pipe tank 3 and the indoor space will also be brought into the greenhouse, thereby achieving the purpose of indoor CO2 enrichment.

[0019] (6) During the initial stage of straw fermentation, a part of the heat of the high-temperature air in the greenhouse and the upper pipe tank 3 will also be transmitted to the straw in the lower pipe tank 1 through the perforated partition 2 under the action of the temperature difference, thereby increasing the temperature of the straw and promoting fermentation.

[0020] (7) Through the soil temperature sensor 9 embedded in the pipe wall, the marginal soil temperature of the greenhouse can be sensed in real time, and the data is uploaded to the control device 12 in time to judge the cold prevention and temperature increase effect of the system.

[0021] (8) Through the CO2 concentration sensor 11 arranged in the upper pipe tank 3, the change rule and enrichment of the CO2 concentration in the pipe tank can be sensed in real time, and the data is uploaded to the control device 12 in time to judge the straw fermentation time, reaction progress and straw replacement time.

[0022] (9) When the straw fermentation process is completed and the planting period is not yet completed, the straw can be replaced by disassembling the ventilation pipe 4, the exhaust pipe 5, the upper pipe tank 3 and the perforated partition 2. The fermented straw replaced out can be directly returned to the field.

[0023] (10) According to the indoor air temperature and the air temperature in the upper pipe tank 3, the starting and stopping time of the variable frequency fan 6 is controlled by the automatic control device 12. According to the CO2 concentration of the indoor air and the air in the upper pipe tank 3, the air volume of the variable frequency fan 6 is adjusted to achieve the goal of active regulation of the greenhouse soil marginal cold prevention and temperature increase and indoor gas enrichment.

[0024] The present application has the advantages that the developed system aims at the two industrial difficulties of low temperature of marginal soil of greenhouse and insufficient CO2 supplement technology of greenhouse, and provides a technical solution; the developed system couples the recycling of surplus air heat in the greenhouse with the gas and heat production of straw fermentation reaction, and uses waste crop straw as raw material for fermentation to produce gas and heat, and the fermented straw can be directly returned to the field to improve soil quality, so that the system makes the greenhouse planting system have the characteristics of energy and material circulation; the developed system has the characteristics of modularity and assembly, and the size, quantity and straw consumption of the optimized components can be flexibly designed and installed according to the size of the greenhouse; the cold-proof pipeline of the system is installed below the surface of the marginal soil of the greenhouse, does not occupy the space of the greenhouse and the cultivated area, can be removed at any time according to the needs of cultivation, does not damage the cultivated land, and does not affect the re-cultivation of the soil. In summary, the developed system has the characteristics of simple technology, scientific principle, convenient material selection, low cost, clear control target, energy saving and low carbon in use process, and green ecology. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the active control system for greenhouse cold prevention, temperature increase and gas increase.

[0026] Figure 2 It is a schematic diagram of the system air inlet pipeline.

[0027] Figure 3 It is a schematic diagram of the system air outlet pipeline.

[0028] Figure 4 It is a soil temperature change rule diagram of the test greenhouse and the control greenhouse, wherein (a) is the soil temperature at a depth of 20 cm, and (b) is the soil temperature at a depth of 30 cm.

[0029] Figure 5 It is a CO2 concentration change rule diagram of the test greenhouse and the control greenhouse, wherein (a) is the position near the ground in the south of the greenhouse, (b) is the position at the top of the crop canopy in the south of the greenhouse, (c) is the position near the ground in the middle of the greenhouse, and (d) is the position at the top of the crop canopy in the middle of the greenhouse. DETAILED DESCRIPTION

[0030] The present application provides an active control system and method for cold prevention, temperature increase and gas increase in the marginal soil of greenhouse. The present application will be described below with reference to the accompanying drawings.

[0031] As Figure 1The whole structure of the greenhouse cold-proof, temperature-increasing and air-increasing active control system is shown in the schematic diagram, and the greenhouse cold-proof, temperature-increasing and air-increasing system is mainly composed of a cold-proof pipe, a ventilation pipe, a variable frequency fan, a temperature sensor, a CO2 concentration sensor and an automatic control system; wherein the cold-proof pipe groove is installed below the marginal soil surface of the lower part of the greenhouse; the cold-proof pipe groove is assembled by a lower pipe groove, a middle hole partition plate 2 and an upper pipe groove 3, the hole partition plate 2 is placed between the lower pipe groove 1 and the upper pipe groove 3; the ventilation pipe includes an air inlet pipe 4 and an air outlet pipe 5, the air inlet pipe 4 is installed at both ends of the upper pipe groove 3, the air outlet pipe 5 is installed at the middle part of the upper pipe groove 3, and a variable frequency fan 6 for ventilation control is arranged inside; the lower pipe groove 1 is filled with straws; a soil temperature sensor 9, an indoor air temperature sensor 10 and a CO2 concentration sensor 11 are installed at appropriate positions inside the greenhouse, and an automatic control device 12 inside the greenhouse is connected with the variable frequency fan 6, the soil temperature sensor 9, the indoor air temperature sensor 10 and the CO2 concentration sensor 11 respectively, and the opening and air volume of the variable frequency fan 6 are controlled according to the temperature parameters and CO2 concentration detected by the sensors.

[0032] The lower pipe groove 1 is a semicircular, arc-shaped or square pipe groove, and the groove opening faces upward during use, mainly used for bearing straws and serving as a container for straw fermentation; the lower pipe groove 1 can be made of PVC, cement, concrete and other materials with good moisture resistance, corrosion resistance and thermal conductivity (as shown in Figure 1

[0033] The hole partition plate 2 is mainly used for separating the lower pipe groove 1 and the upper pipe groove 3, and the partition plate is provided with uniformly distributed air holes with a diameter of 1 cm, which can prevent the soil or straws from being blocked and can timely transport the CO2 gas generated by the straw fermentation in the lower pipe groove 1 to the upper pipe groove 3.

[0034] The upper pipe groove 3 is a semicircular or arc-shaped pipe groove, and the groove opening faces downward during use and is placed on the lower pipe groove 1; an air convection space is formed between the upper pipe groove 3 and the hole partition plate 2; the upper pipe groove can be made of PVC, cement or concrete with good moisture resistance, corrosion resistance and thermal conductivity.

[0035] As shown in Figure 2 and Figure 3 The air inlet pipe 4 and the air outlet pipe 5 installed on the upper pipe groove 3 are inserted into the upper pipe groove 3 through local holes of the upper pipe groove 3 and are connected and fixed through the L-shaped joint 7 and the T-shaped joint 8 arranged on the upper pipe groove 3.

[0036] The air inlet pipe 4 is arranged at a height of 0.5 m from the ground to prevent the soil and sundries from falling into the pipe and being blocked; the air outlet pipe 5 is arranged at a height of 1.0 m from the ground to facilitate the discharge of the air rich in CO2 to the crop canopy height; the pipe material can be selected from PVC with good lightness and durability.

[0037] ​The variable frequency fan 6 is installed at the bottom of the exhaust pipe 5, and is used for forced convection of air inside and outside the pipe.

[0038] The soil temperature sensor 9 is installed in the soil near the pipe wall of the upper pipe groove 3, and the air temperature sensor 10 is installed in the range of the crop canopy height.

[0039] The CO2 concentration sensor 11 is installed in the upper pipe groove 3 respectively, for detecting the CO2 concentration in the upper pipe groove 3; and is installed near the crop canopy height in the indoor space, for detecting the CO2 concentration of the indoor air.

[0040] An active control method for a greenhouse soil marginal cold-proof and indoor air increase active control system, characterized in that a cold-proof pipe groove is arranged below the ground surface at the low-temperature soil marginal position in the greenhouse, and straw is placed in the pipe groove, and the straw fermentation produces CO2 gas and heat; the CO2 gas is transmitted to the indoor air through the pipeline system, and the generated heat is mainly transmitted to the surrounding soil through the pipe wall, so as to achieve the purpose of soil marginal cold-proof and indoor air increase; in addition, with the circulation and exchange between the air in the pipe and the indoor air, the excess heat in the greenhouse during the day enters the upper pipe groove, and also transmits to the surrounding soil through the pipe wall under the action of temperature difference, further improving the cold-proof and warming effect of the system on the marginal soil of the greenhouse. The active control method of the cold-proof and indoor air increase active control system is as follows:

[0041] (1) The cold-proof pipe groove is buried below the ground surface at a position with lower surrounding soil temperature in the greenhouse, the lower pipe groove 1 is filled with straw, the air inlet pipe 4 is installed at both ends of the upper pipe groove 3, the exhaust pipe 5 is installed at the middle of the upper pipe groove 3, and the variable frequency fan 6 for ventilation control is arranged inside; the cold-proof pipe groove not only insulates the direct heat transfer between the inside and outside of the surrounding soil, but also plays a role in heat preservation and cold-proof, and at the same time, the upper pipe groove 3 can realize heat exchange and CO2 transmission between the greenhouse and the space of the upper pipe groove 3 through the forced convection of the variable frequency fan 6;

[0042] (2) The CO2 gas produced by the fermentation of the straw in the lower pipe groove 1 diffuses to the space of the upper pipe groove 3 through the perforated partition plate 2; the heat generated by the fermentation of the straw in the lower pipe groove 1 is transmitted to the surrounding soil under the action of the temperature difference between the inside and outside of the pipe wall, and is stored in the surrounding soil, so as to improve the temperature of the surrounding soil, and achieve the effect of deep soil cold-proof and warming;

[0043] (3) The temperature sensor detects the temperature of the soil around the pipe wall of the upper pipe groove 3 and the space of the crop canopy height in the indoor space; the CO2 concentration sensor 11 detects the CO2 concentration of the crop canopy height in the upper pipe groove 3 and the greenhouse air, and transmits the detected data to the automatic control device 12; the automatic control device 12 automatically controls according to the target control parameters obtained by the above detection;

[0044] (4) During the day, under the forced convection of the variable frequency fan 6, the indoor high-temperature air can be introduced into the upper pipe groove 3, and under the action of the temperature difference between the inside and outside of the pipe wall, it is transmitted to the surrounding soil to store, thereby raising the surrounding soil temperature, achieving the purpose of shallow soil cold prevention and temperature increase;

[0045] (5) During the day, under the forced convection of the variable frequency fan 6, along with the convection exchange between the upper pipe groove 3 and the indoor space, the high-concentration CO2 contained therein will also be brought into the greenhouse, thereby achieving the purpose of indoor CO2 increase;

[0046] (6) In the initial stage of straw fermentation, the high-temperature air in the greenhouse and the upper pipe groove 3 will also have a part of the heat transmitted to the straw in the lower pipe groove 1 through the perforated partition plate 2 under the action of the temperature difference, so as to increase the temperature of the straw and promote fermentation;

[0047] (7) Through the soil temperature sensor 9 embedded around the pipe wall, the marginal soil temperature of the greenhouse can be sensed in real time, and the data is uploaded to the control device 12 in time to judge the cold prevention and temperature increase effect of the system;

[0048] (8) Through the CO2 concentration sensor 11 arranged in the upper pipe groove 3, the change rule and increase of the CO2 concentration in the pipe groove can be sensed in real time, and the data is uploaded to the control device 12 in time to judge the straw fermentation time, reaction progress and straw replacement time;

[0049] (9) When the straw fermentation process is completed and the planting period is not completed, the straw can be replaced by disassembling the ventilation pipe 4, the exhaust pipe 5, the upper pipe groove 3 and the perforated partition plate 2; the fermented straw replaced out can be directly returned to the field;

[0050] (10) According to the indoor air temperature and the air temperature in the upper pipe groove 3, the starting and closing time of the variable frequency fan 6 is controlled through the automatic control device 12; according to the CO2 concentration of the indoor air and the air in the upper pipe groove 3, the air volume of the variable frequency fan 6 is adjusted, so as to realize the active control target of the greenhouse soil marginal cold prevention and temperature increase and indoor air increase.

[0051] Embodiment

[0052] The cold-proof pipe of the present application is buried below the ground surface at the low-temperature margin of the greenhouse according to the facility form and needs, CO2 generated by straw fermentation enters the upper pipe groove 3 through the perforated partition plate 2, the fermentation heat can be transmitted to the surrounding soil through the pipe wall of the lower pipe groove 1 under the action of temperature difference, and the temperature of the deep marginal soil of the greenhouse is raised to achieve the purpose of active cold-proof and warming; the variable frequency fan 6 can open to realize the air convection circulation between the greenhouse and the upper pipe groove 3, and the excess heat in the indoor high-temperature air can be taken to the underground during the day, and under the action of temperature difference, most of the heat will be transmitted to the surrounding soil through the heat transfer of the wall of the upper pipe groove 3, and the temperature of the shallow marginal soil of the greenhouse is raised to achieve the effect of active cold-proof and warming; at the same time, in the early stage of straw fermentation, the temperature of the straw is relatively low, and under the action of temperature difference, part of the heat will also be transmitted to the straw, which plays a role in promoting straw fermentation.

[0053] The above design was implemented and compared in two solar greenhouses in Beijing Tongzhou base from January to February 2022, and the test contents included air CO2 concentration and greenhouse soil temperature; the data from January 17 to January 27 before and after the coldest day were selected for analysis, among which January 17-20 and 22, 24 and 26 were cloudy, January 21 was a small snow, January 23 and 24 were overcast, and January 25 and 27 were sunny, but because the heat preservation was repaired on January 25, it was not completely rolled up that day, so this period was the most unfavorable condition of the whole greenhouse temperature and light condition.

[0054] The temperature test results are shown in the following Figure 4 (a) 20cm deep soil temperature; (b) 30cm deep soil temperature; it can be seen that the soil temperature of the test greenhouse is obviously higher than that of the control greenhouse; the specific statistical results are shown in Table 1, the soil temperature at the depth of 20cm and 30cm in the test greenhouse is respectively increased by 28.4% and 12.1% than that at the same depth in the control greenhouse, which plays a good role in improving the soil temperature and resisting the influence of bad weather on the soil temperature of the greenhouse.

[0055] Table 1. Comparison of soil temperature change data between test greenhouse and control greenhouse

[0056]

[0057] The CO2 concentration test results are shown in the following Figure 5 (a) the air CO2 concentration of four indoor space position measuring points of the greenhouse, (b) the air CO2 concentration of the top surface of the crop canopy in the south of the greenhouse; (c) the air CO2 concentration of the top surface of the crop canopy in the middle of the greenhouse; (d) the air CO2 concentration of the top surface of the crop canopy in the middle of the greenhouse; all of them show that the test greenhouse is higher than the control greenhouse. The specific statistical results are shown in Table 2, and the average CO2 concentration is increased by 17.12%.

[0058] Table 2. CO2 concentration in the test greenhouse and the control greenhouse

[0059]

[0060] In summary, the present application can realize timely, accurate and active regulation of the greenhouse environment according to the changes of the greenhouse environment, and can achieve the goal of active regulation of the marginal cold prevention and temperature increase of the greenhouse soil and the indoor air increase.

Claims

1. An active control system for greenhouse cold protection, heating and air enhancement, characterized in that: The active control system for preventing cold, increasing temperature and increasing air in the greenhouse mainly consists of a cold-proof pipe trough, a ventilation pipe, a variable frequency fan, a temperature sensor, a CO2 concentration sensor and an automatic control device; wherein the cold-proof pipe trough is installed below the soil surface at the lower edge of the greenhouse; it is assembled from three parts: a lower pipe trough (1), a middle perforated partition (2) and an upper pipe trough (3); the perforated partition (2) is placed between the lower pipe trough (1) and the upper pipe trough (3); the ventilation pipe includes an air inlet pipe (4) and an air exhaust pipe (5), the air inlet pipe (4) is installed at both ends of the upper pipe trough (3), and the air exhaust pipe (5) is installed in the middle of the upper pipe trough (3), and the variable frequency fan for ventilation control is built in. The lower pipe groove (1) is filled with straw; the soil temperature sensor (9), the indoor air temperature sensor (10), and the CO2 concentration sensor (11) are installed at appropriate positions inside the greenhouse, and the automatic control device (12) inside the greenhouse is connected to the variable frequency fan (6), the soil temperature sensor (9), the indoor air temperature sensor (10), and the CO2 concentration sensor (11), respectively, and the opening and air volume of the variable frequency fan (6) are controlled according to the temperature parameters and CO2 concentration parameters detected by the sensors; the lower pipe groove (1) can be a semicircular, arc-shaped or square pipe groove, and the groove opening is oriented in the direction of the wind when in use. The upper portion is mainly used for carrying straw and serving as a container for straw fermentation; the lower pipe trough (1) is preferably made of PVC, cement or concrete materials with good moisture resistance, corrosion resistance and thermal conductivity; the perforated partition (2) is mainly used to separate the lower pipe trough (1) and the upper pipe trough (3), and the partition is provided with uniformly dense ventilation holes with a hole diameter of 1 cm, which can prevent clogging due to soil or straw, and can transmit the CO2 gas generated by the fermentation of straw in the lower pipe trough (1) to the upper pipe trough (3) in a timely manner; the upper pipe trough (3) is a semicircular or arc-shaped pipe trough, and when in use, the notch is placed on the lower pipe trough (1); the upper pipe trough (3) An air convection space is formed between the lower pipe trough (1) and the upper pipe trough (3) by a perforated partition plate (2); the upper pipe trough (3) is preferably made of PVC, cement or concrete with good moisture resistance, corrosion resistance and thermal conductivity; the air inlet pipe (4) and the air exhaust pipe (5) installed on the upper pipe trough (3) are inserted into the upper pipe trough (3) through the local opening of the upper pipe trough (3) and fixed by an L-shaped joint (7) and a T-shaped joint (8) provided on the upper pipe trough (3); the opening of the air inlet pipe (4) is 0.5m above the ground to prevent soil and debris from falling in and clogging; the opening of the air exhaust pipe (5) is 1.0m, so as to discharge CO2-rich air to the height of the crop canopy; the pipe material should be lightweight and durable PVC material; the variable frequency fan (6) is installed at the bottom of the exhaust pipe (5) for forced convection of air inside and outside the pipe; the soil temperature sensor (9) is installed in the soil near the pipe wall of the upper pipe groove (3), and the indoor air temperature sensor (10) is installed within the height range of the crop canopy; the CO2 concentration sensor (11) is respectively installed in the upper pipe groove (3) for detecting the CO2 concentration in the upper pipe groove (3); and is installed near the height of the indoor crop canopy for detecting the CO2 concentration in the indoor air.

2. An active control method for a greenhouse cold protection, heating, and air enhancement active control system, characterized in that: A cold-proof pipe trough is set below the ground surface at the low-temperature soil edge in the greenhouse. Straw is placed in the pipe trough. The straw ferments to produce CO2 gas and heat, which is exchanged with heat and mass in the greenhouse to achieve the purpose of indoor air increase and soil edge temperature increase and cold-proof. The cold-proof temperature increase and indoor air increase active control system is actively regulated. The specific active control method is as follows: (1) The cold-proof pipe trough is buried below the ground surface at a location where the surrounding soil temperature is relatively low in the greenhouse, straw is filled in the lower pipe trough (1), the air inlet pipe (4) is installed at both ends of the upper pipe trough (3), the air exhaust pipe (5) is installed in the middle of the upper pipe trough (3), and a variable frequency fan (6) for ventilation control is built in; the cold-proof pipe trough not only isolates the direct heat transfer between the inside and outside of the soil surrounding the greenhouse, but also plays a role in heat preservation and cold prevention. At the same time, the upper pipe trough (3) can realize heat exchange and CO2 transmission between the greenhouse and the upper pipe trough (3) through the forced convection of the variable frequency fan (6); (2) The CO2 gas generated by the fermentation of straw in the lower tube trough (1) will diffuse into the space of the upper tube trough (3) through the perforated partition (2); the heat generated by the fermentation of straw in the lower tube trough (1) will be transferred to the surrounding soil for storage under the action of the temperature difference between the inside and outside of the tube wall, thereby increasing the temperature of the surrounding soil and playing the role of cold protection and warming of the deep soil; (3) The temperature sensor detects the spatial temperature in the soil around the pipe wall of the upper pipe trough (3) and in the indoor space at the height of the crop canopy; the CO2 concentration sensor (11) detects the CO2 concentration in the upper pipe trough (3) and in the greenhouse air at the height of the crop canopy, and transmits the above data to the automatic control device (12), which automatically controls according to the detected data and the set target control parameters; (4) During the day, under the forced convection of the variable frequency fan (6), the indoor high-temperature air can be introduced into the upper tube groove (3). Under the action of the temperature difference between the inside and outside of the tube wall, the air is transferred to the surrounding soil for storage, thereby raising the temperature of the surrounding soil and achieving the purpose of cold protection and warming of the shallow soil. (5) During the day, under the forced convection of the variable frequency fan (6), as the convection exchange between the upper tube trough (3) and the indoor space occurs, the high concentration of CO2 contained therein will also be brought into the greenhouse, thereby achieving the purpose of increasing CO2 indoors; (6) In the early stage of straw fermentation, due to the temperature difference, some of the heat from the high-temperature air in the greenhouse and the upper tube trough (3) will be transferred to the straw in the lower tube trough (1) through the perforated partition (2), thereby increasing its temperature and promoting fermentation. (7) The soil temperature sensor (9) buried around the pipe wall can instantly sense the marginal soil temperature of the greenhouse, and the data is promptly uploaded to the automatic control device (12) to judge the cold-proof and warming effect of the system; (8) The CO2 concentration sensor (11) installed in the upper pipe trough (3) can instantly sense the changing pattern of CO2 concentration in the pipe trough and the application situation, and the data is transmitted to the automatic control device (12) in a timely manner to determine the straw fermentation time, reaction process and straw replacement time; (9) When the straw fermentation process is completed but the planting cycle is not yet completed, the straw can be replaced by disassembling the air inlet pipe (4), the exhaust pipe (5), the upper pipe groove (3) and the perforated partition (2); (10) According to the indoor air temperature and the air temperature in the upper tube trough (3), the start and shut-down time of the variable frequency fan (6) is controlled by the automatic control device (12); according to the CO2 concentration of the indoor air and the air in the upper tube trough (3), the air volume of the variable frequency fan (6) is adjusted to achieve the goal of marginal cold protection and warming of the greenhouse soil and active regulation of indoor air increase.

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