CN109601207B - Ground-assisted enhanced greenhouse roof truss solar heat collection and release system and control method - Google Patents

Abstract

The invention discloses a ground auxiliary enhanced greenhouse roof truss solar heat collecting and releasing system and a regulating method, belonging to the field of environmental control of facility agriculture engineering. In a greenhouse roof truss solar heat collecting and releasing system, a ground pipe network system, an underground reservoir and a control system are added; the greenhouse roof truss solar heat collecting and releasing system is divided into three independent pipe network systems of a roof truss upper chord, a roof truss lower chord and a ground pipe network, wherein each independent pipe network system is provided with an independent water pump and can independently operate; the function of winding the roof truss is adjusted to have the heat collecting function only; the heat is prevented from being easily lost through the roof; the heat collecting and releasing system is used for heat storage in the daytime and heat release at night, so that time-sharing and sectional regulation and control are realized; the combined heat release mode of the ground pipe network and the roof truss lower chord pipe network ensures that the heat release position is more reasonable, realizes the targeted heating of the root and canopy spaces of crops, and improves the utilization efficiency of the accumulated heat. The problem of insufficient heat storage of the system in a specific period such as a seedling stage of crops is solved pertinently.

Description

Ground-assisted enhanced greenhouse roof truss solar heat collection and release system and control method

Technical field

The invention belongs to the field of facility agricultural engineering environment control, and particularly relates to a ground-assisted enhanced greenhouse roof truss solar heat collection and release system and a control method.

Background technique

Since the reform and opening up, the economy has continued to develop rapidly, and people's demand for facility planting products has greatly increased. my country's greenhouse construction has entered a period of rapid development. The solar greenhouse is a greenhouse type independently developed in my country. Its structural characteristics are that the south roof is made of transparent plastic film as the main light-transmitting covering material, and the east and west gables, north walls and north roof are thermal insulation and heat storage structures. During the day, part of the solar energy entering the greenhouse through the light-transmitting surface is absorbed and stored by the wall and soil; at night, as the indoor temperature drops, when the indoor temperature is lower than the temperature of the wall and soil, the wall and soil will store the solar energy during the day. The heat is gradually released, thus maintaining a constant indoor temperature.

According to incomplete statistics, solar greenhouses currently account for about a quarter of the total area of facility horticulture, most of which are distributed in northern areas and are used for the production of winter vegetables, flowers and other crops. Because it can make full use of solar energy resources, it has better self-insulation and heat storage and release properties compared to other greenhouses, and consumes less fossil fuels. Therefore, it solves the long-term inability to produce vegetables in winter in northern my country at a lower cost. . Its advantages of low cost and huge benefits have also stimulated farmers' enthusiasm for production. While increasing farmers' income, it has promoted the development of the entire facility agriculture industry and made outstanding contributions to my country's economic and social development.

However, there are still many problems during the use of solar greenhouses. For example, due to the limited heat storage capacity of the walls and floors, most of the solar energy entering the greenhouse cannot be effectively utilized. Ventilation is often required during the day to alleviate indoor high temperature problems, while another On the other hand, although overwintering production without heating can be achieved in many areas in the north, low temperature phenomena still occur frequently; in addition, due to the need for heat preservation, greenhouses usually pay attention to sealing at night. In addition, due to the influence of low temperature, the relative humidity is very high, causing The time is close to 100%. This environment can easily induce diseases and affect plant growth and yield.

In terms of how to make full use of solar energy and store the excess heat in the greenhouse during the day for nighttime heating to improve the solar energy utilization efficiency of the greenhouse, Ma Chengwei and others invented the roof-truss solar collector solar greenhouse, which contains a roof-truss pipe network-based solar greenhouse. The components of the heat release system. This system makes the greenhouse load-bearing roof truss into a water pipe, and a water circulation loop is formed by the lower chord pipe, the upper chord pipe and the underground reservoir. The solar radiation heat that shines on the roof truss during the day is brought to the underground pool through the circulating water and stored in the water. , the same circulating water flows at night, and then the heat is released by the roof truss, which plays the role of greenhouse heating. The technology invented by Ma Chengwei and others has obvious heat collection and heat release effects, and because it uses the existing greenhouse roof truss, the investment cost is low, it does not affect the normal lighting of the greenhouse, does not occupy any indoor planting space, and does not affect the greenhouse production management. It is a very Good design ideas. However, it was found during use that this system still has two problems. First, the number of greenhouse roof trusses is limited, and the heat collection during the day needs to be improved. Second, the roof truss is located at the top of the greenhouse, and the heat release position at night is too high, which has a heating effect on the crop canopy space in the lower part of the greenhouse. It is not ideal and the heat utilization efficiency is not high; third, the upper strings of the roof truss are in contact with the film on the light-transmitting surface. The transparent surface is the place with the weakest thermal insulation ability at night, so a large part of the heat emitted by the upper strings of the roof truss directly passes through the roof. Dissipated to the outside, causing waste of heat.

In view of the above reasons, the present invention will propose technical improvement plans and corresponding control methods for the problems such as insufficient heat collection area, excessive heat release position, and low heat utilization efficiency of the system, so as to achieve better effects for this technology, and Provide technical support to truly solve practical problems in production.

Contents of the invention

The object of the present invention is to propose a ground-assisted enhanced greenhouse roof truss solar heat collection and release system and a control method. The greenhouse roof truss solar heat collection and release system has a roof truss connected by web rods in the middle of the upper and lower chords. , the roof trusses are fixed on the east and west gables and the north wall, and the top surface of the roof trusses and the south side roof are covered with light-transmitting materials of transparent plastic film to form a solar greenhouse, which is the greenhouse roof truss solar heat collection and release system; it is characterized by:

First of all, in the greenhouse roof truss solar heat collection and release system, a ground pipe network system, an underground reservoir and a control system are added; it can be used for heat storage during the day and heat release at night;

Secondly, the greenhouse roof truss solar heat collection and release system is divided into three independent pipe network systems: the upper chord, the lower chord of the roof truss and the ground pipe network. Each has an independent water pump and can operate independently, forming a ground-assisted enhanced greenhouse roof truss solar heat collection and release system; Adjust the function of the roof trusses to only have a heat collection function; to prevent heat from being easily lost through the roof.

The roof truss pipe network part consists of an upper chord pipe, a lower chord pipe, an upper chord water supply main pipe, a lower chord water supply main pipe, an upper chord water supply branch pipe, a lower chord water supply branch pipe, a roof return water main pipe, an upper chord pipe network water pump, a lower chord pipe network water pump, and corresponding independent It consists of a control valve; in addition to meeting the structural requirements, the upper and lower chords should be able to withstand the necessary pressure required for water circulation, and the surface needs to be blackened to enhance the heat absorption capacity.

The ground pipe network part includes ground water supply main pipes, return water main pipes, inter-row branch pipes, main pipe control valves, branch pipe control valves, and water pumps. Except for the requirement that the joints be able to withstand the necessary water pressure, there are no other specific requirements for pipe materials;

The control system includes: control box, temperature and humidity measurement module, electromagnetic control valve and pipeline control valve

The heat collection and release control method of the ground-assisted enhanced greenhouse roof truss solar heat collection and release system is characterized in that the heat collection and release of the heat collection and release system realizes time-based and segmented control. The specific principles are as follows:

(1) During the low-growing stage of crop plants such as the seedling stage, the demand for ambient temperature is relatively high. In view of this, three pipe network systems, namely the upper and lower roof trusses and the ground, are activated to collect heat at the same time during the day. Among them, the ground pipe network heat collection system It mainly collects part of the solar radiation transmitted to the ground and accumulates it in the pool, which has the effect of increasing the heat collection area and meeting the needs of special periods. At night, the ground pipe network heat release system is first started to heat the roots. Part of the heat released is based on the principle of hot air rising and will gradually be transferred to cover the entire crop canopy. The other part will directly heat the root soil due to contact with the soil. Improve the temperature environment of the root circle, so all the heat is utilized instead of wasted; when the temperature is low and the ground heat radiation is insufficient, the lower chord pipe network of the roof truss is activated to participate in heat release. This part of the heat will lift the top growth point of the crop canopy. temperature.

(2) During the peak growth period of crops, the resistance of crops to low temperature environments increases accordingly. At this time, the shielding of the ground by tall plants reduces the amount of solar radiation received by the ground. Therefore, heat collection during the day is mainly carried out through the upper and lower chord pipe networks of the roof trusses; while heat dissipation at night is still given priority to the ground pipe network. If insufficient, it will be restarted. The lower chord pipe network of the roof truss participates in heat release.

The ground pipe network enhances the heat collection capacity of the entire system and specifically solves the problem of insufficient heat storage in the system during specific periods such as the crop seedling stage. The combined heat release method of the ground pipe network and the roof truss lower chord pipe network makes the heat release position more reasonable, achieves targeted heating of crop roots and canopy space, and improves the utilization efficiency of accumulated heat.

The time-sharing and segmented control: during the heat storage stage during the day, when the indoor air temperature is higher than the water temperature and the temperature difference is greater than or equal to 2°C, under the condition that the crops are low and the ground can receive solar radiation, the ground pipe network and roof truss winding, The controlled water pump of the lower chord pipe network, through the circulation of water in the pipe network, collects the solar radiation heat that shines on the ground pipe network and the upper and lower chord pipe networks of the roof truss and brings it to the underground reservoir. The water body is heated and the heat is accumulated. ; When the difference between indoor air temperature and water temperature is less than 2℃, the operation of the roof truss upper and lower pipe network heat collection system stops; in the night heat release stage, when the indoor temperature is lower than the set temperature and 2℃ lower than the water temperature, it starts first The ground pipe network controls the water pump. The warm water in the pool circulates in the ground pipe network. The heat is released to the area near the surface through the ground pipe network, that is, the roots of the crops. While heating the root soil and air environment, the hot air floats up. principle, it will also gradually heat the upper canopy space; in extreme cold weather conditions, the indoor ambient temperature continues to decrease, and the ground cooling system is not enough to maintain a constant temperature inside the greenhouse, and the lower chord pipe network of the roof truss is started to control the water pump at the same time, and the heat passes through the ground pipe network It is emitted indoors at the same time as the lower chord pipe network of the roof truss, increasing the temperature at the roots of crops and the top of the canopy. Since there is a distance of more than 30cm between the lower chord and the upper chord of the roof truss and the light-transmitting surface, it can effectively prevent part of the heat from being directly dissipated from the roof, which is beneficial to improving the utilization efficiency of accumulated heat.

The beneficial effects of the present invention are as follows:

(1) The present invention combines the roof truss pipe network system and the ground pipe network system to collect solar radiation heat entering the greenhouse to a greater extent, and overcomes the problem of insufficient heat storage area in the prior art.

(2) The present invention controls the upper chord pipe network and the lower chord pipe network of the roof truss heat collection system separately and independently. The upper chord pipe network is only used as a heat collection system, and the lower chord pipe network is used as both a heat collection and heat release system. It avoids the problem of heat loss caused by contact with the film on the light-transmitting surface when the upper chord pipe network is used as a heat dissipation system.

(3) The added ground pipe network system, especially in the low seedling stage of crops and during periods when indoor temperatures require higher temperatures, has a heat storage function during the day, which improves the heat storage capacity of the system in a specific period.

(4) The added ground pipe network system is located at the roots of cultivated row crops. It is first started as a heat release system, which can release the heat directly to the roots of the crops. Part of it heats the root air upwards, and because of the principle of the hot air floating up, it gradually Heating the upper crop canopy space; part of it is in contact with the ground and emitted into the soil, increasing the root soil temperature and significantly improving the utilization efficiency of the required heat.

(5) The added ground pipe network system, combined with the upper and lower chord pipe networks of the roof truss, makes the heat storage and heat release functions more clearly divided, the heat release position is more reasonable, and time-based and segmented regulation can be realized to meet different growth periods and different conditions. Weather and environmental requirements.

Description of the drawings

Figure 1 is the structural diagram of the ground-assisted enhanced greenhouse roof truss solar heat collection and release system;

Figure 2 is a side view of the ground-assisted enhanced greenhouse roof truss solar heat collection and release system.

Figure 3 is a schematic diagram of the ground pipe network system. .

Description of the numbers in the figure: 1-upper chord; 2-lower chord; 3-upper chord electromagnetic control valve; 4-lower chord electromagnetic control valve; 5-bottom chord upper water main pipe of the roof truss heat collecting system; 6-roof truss hose; 7-Electromagnetic control valve of the ground cooling main pipe; 8-Electromagnetic control valve of the water main pipe under the roof truss; 9-Ground water return main pipe; 10-Ground branch pipe; 11-Ground water main pipe; 12-Ground pipe return port; 13-Roof truss pipe Water return port; 14-Water pump (three groups); 15-Reservoir; 16-Control box; 17-Roof truss return water main pipe; 18-Roof truss top water main pipe electromagnetic control valve; 19-Roof truss heat collection system top water main pipe ; 20-Temperature and humidity monitoring module; 21-Hydraulic flow meter; 22-North wall; 23-Insulation quilt;

Detailed ways

The invention proposes a ground-assisted enhanced greenhouse roof truss solar heat collection and release system and a control method. In the greenhouse roof truss solar heat collection and release system, the roof truss is connected by web rods in the middle of the upper chord tube and the lower chord tube, and the roof truss is fixed. On the east and west gables and the north wall, the top surface of the roof truss and the south side roof are covered with light-transmitting materials of transparent plastic film to form a solar greenhouse, which is the greenhouse roof truss solar heat collection and release system; as shown below in conjunction with Figures 1 and 2 , a detailed description of the structure and operation of the ground-assisted enhanced greenhouse roof truss solar heat collection and release system:

The present invention adds a ground-to-ground pipe network system, an underground reservoir and a control system to the greenhouse roof truss solar heat collection and release system. The ground-assisted enhanced greenhouse roof truss solar heat collection and release system is divided into three independent pipe network systems: the roof truss upper chord system, the lower chord pipe network system and the ground pipe network system. Each has an independent water pump and can operate independently; the functions of the roof truss upper chord pipe network system are divided into three independent pipe network systems. , which originally had both heat collection and heat release functions, was adjusted to only have a heat collection function, solving the problem in the original technology that the heat release position was too high and heat was easily lost through the roof. Improve and perfect the heat collection and heat release system mentioned in the roof-truss solar collector solar greenhouse, increase its heat storage area, improve the heat release method, and improve the greenhouse utilization efficiency of the heat released.

As shown in Figure 1 and Figure 2, the structural diagram of the ground-assisted enhanced greenhouse roof truss solar heat collection and release system; the roof truss upper chord and lower chord pipe network: the roof truss is connected by web rods in the middle of the upper chord 1 and the lower chord 2. The roof truss It is fixed on the east and west gables and the north wall 22. The top surface of the roof and the south side roof are covered with light-transmitting materials of transparent plastic film. The upper chord electromagnetic control valve 3 and the lower chord pipe are respectively connected to the ground sections of the upper chord 1 and the lower chord 2. The electromagnetic control valve 4; the water main pipe 5 of the roof truss heat collection system is connected to the upper chord electromagnetic control valve 3 and the lower chord electromagnetic control valve 4 respectively through the roof truss connecting hose 6; the roof water main pipe control valve 8 is connected to the water pressure flow integrated meter 21 between the lower chord electromagnetic control valve 4 and the reservoir water pump 14; the roof upper chord upper water main electromagnetic control valve 18 and the hydraulic flow integrated meter 21 are connected between the upper chord electromagnetic control valve 3 and the reservoir water pump 14; the roof truss The upper water main pipe 19 of the heat collecting system is connected between the upper pipe electromagnetic control valve 3 and the reservoir water pump 14; the reservoir water pump 14; the roof truss return main pipe 17 is connected to the roof truss pipe return port 13 and inserted into the reservoir 15 ; The control box 16 is fixed on the north wall 22, and the temperature and humidity monitoring module 20 of the control system is supported under the enhanced greenhouse roof truss; the insulation quilt 23 is fixed on the top surface of the roof truss.

As shown in Figure 1 and Figure 3. The ground pipe network includes: the ground heat dissipation main pipe control valve 7 and the hydraulic flow integrated meter 21 are connected between the ground return water main pipe 9 and the reservoir water pump 14; the ground branch pipe 10 connects the ground upper water main pipe 11 and the ground return water main pipe 9 A ground pipe network is formed, and is inserted into the reservoir 15 through the ground pipe return port 12; the ground pipe network enhances the heat collection capacity of the entire system, and specifically solves the problem of insufficient heat storage in the system during specific periods such as the seedling stage of crops. The combined heat release method of the ground pipe network and the roof truss lower chord pipe network makes the heat release position more reasonable, achieves targeted heating of crop roots and canopy space, and improves the utilization efficiency of accumulated heat.

The upper chord 1 and the lower chord 2 are processed from ordinary steel water pipes. The water main pipe 5 on the lower chord of the roof truss is mainly responsible for sending water to the lower chord 2. The electromagnetic control valve 3 controls the switch of the upper chord 1. The water main pipe 19 of the upper chord of the roof truss is mainly responsible for sending water to the upper chord 1. At the position of the north wall 22, there is a roof truss return water main pipe 17, which is responsible for circulating the water in the roof truss upper chord 1 and lower chord 2 to the reservoir 15. When the control system allows the electromagnetic control valve of the roof truss network to open and the water reservoir pump 14 connecting the upper and lower pipes and the lower chords of the roof truss is turned on, the roof water flow cycle is the reservoir 15 → the upper water main pipe 8 of the lower chord of the roof / the upper chord of the roof truss Water supply main pipe 19→lower chord pipe 2/upper chord pipe 1→roof truss return water main pipe 17→reservoir 15. When the control box 16 turns on the water storage pump 14 connected to the ground pipe network, the water flow in the ground pipe network circulates as the reservoir 15 → the ground water main pipe 11 → the ground branch pipe 10 → the ground return water main pipe 9 → the reservoir 15.

In addition to the material requirements for the roof truss pipe network, the present invention does not have specific requirements for the materials and sizes of other system components. The length and pipe diameter can be determined as needed. Paint all heat collecting pipes black or use surface black pipes to enhance the heat absorption effect. All pipes have no specific requirements except that the joints can withstand the necessary water pressure.

The control system includes: control box, temperature and humidity measurement module, electromagnetic control valve and pipeline control valve.

The specific principles of time-sharing and segmented control implemented by the present invention are as follows:

(1) During the low-growing stage of crop plants such as the seedling stage, the demand for ambient temperature is relatively high. In view of this, three pipe network systems, namely the upper and lower roof trusses and the ground, are activated to collect heat at the same time during the day. Among them, the ground pipe network heat collection system It mainly collects part of the solar radiation transmitted to the ground and accumulates it in the pool, which has the effect of increasing the heat collection area and meeting the needs of special periods. At night, the ground pipe network heat release system is first started to heat the roots. Part of the heat released is based on the principle of hot air rising and will gradually be transferred to cover the entire crop canopy. The other part will directly heat the root soil due to contact with the soil. Improve the temperature environment of the root circle, so all the heat is utilized instead of wasted; when the temperature is low and the ground heat radiation is insufficient, the lower chord pipe network of the roof truss is activated to participate in heat release. This part of the heat will lift the top growth point of the crop canopy. temperature. It can be used to store heat during the day to solve the problem of insufficient heat storage area during the low growth period of seedlings and other crops. It can also be used to release heat at night to solve the problem of excessive heat release position and insufficient heat utilization;

(2) During the peak growth period of crops, the resistance of crops to low temperature environments increases accordingly. At this time, the shielding of the ground by tall plants reduces the amount of solar radiation received by the ground. Therefore, heat collection during the day is mainly carried out through the upper and lower chord pipe networks of the roof trusses; while heat dissipation at night is still given priority to the ground pipe network. If insufficient, it will be restarted. The lower chord pipe network of the roof truss participates in heat release.

The actual operation is to start the ground pipe network (under the condition that the crops are low and the ground can receive solar radiation), and the roof truss pipe network (including upper stringing) during the heat storage stage during the day when the indoor temperature is higher than the water temperature and the temperature difference is greater than or equal to 2°C. and bottom string) controls the water pump, and through the circulation of water in the pipe network, the solar radiation heat that hits the ground pipe network and the roof truss pipe network is collected and brought to the underground reservoir. The water body is heated and the heat is accumulated; when the indoor air When the difference between the temperature and the water temperature is less than 2°C, the roof heating system stops. During the heat release stage at night, when the indoor temperature is lower than the set temperature and 2°C lower than the water temperature, the ground pipe network is first started to control the water pump. The warm water in the pool circulates in the ground pipe network, and the heat is released to the pool through the ground pipe network. The area near the surface, that is, the roots of crops; while heating the root soil and air environment, the upper canopy space will gradually heat up due to the principle of hot air rising; in extreme cold weather conditions, the indoor ambient temperature continues to decrease, and the ground dissipates heat When the system is insufficient to maintain a constant temperature inside the greenhouse, the roof truss lower chord pipe network is started to control the water pump at the same time. The heat can be dissipated into the room through the ground pipe network and the roof truss lower chord pipe network at the same time, increasing the temperature of the crop roots and the top of the canopy. Since there is a distance of more than 30cm between the lower chord and the upper chord of the roof truss and the light-transmitting surface, it can effectively avoid the problem of part of the heat being directly dissipated from the roof under the heat dissipation method of the upper chord pipe network in the original patented technology, which is conducive to improving the utilization efficiency of accumulated heat. .

The present invention can adopt different control methods for different crops and crop growth at different stages. There are a total of four control methods:

①Heat collection (ground pipe network + roof truss upper and lower chord pipe network)/heat release (ground pipe network). The advantage of this control mode is that it makes full use of the solar energy shining on the ground. It is suitable for crops in the seedling stage or crops with short plants. During the day, when seedlings or short crops have little shade, the greenhouse floor walkway can still receive a lot of sunlight. The ground pipe network located here can absorb solar radiation heat and store it in the pool through water circulation; the roof truss heat collection system uses The method of supplying water to the upper and lower strings at the same time also converts the absorbed solar energy into internal energy through water circulation and accumulates it in the pool. At night, when the system detects that the temperature in the greenhouse is lower than 10°C and 2°C lower than the water temperature, the ground pipe network system starts to release the heat accumulated in the pool during the day to the vicinity of the greenhouse floor through water circulation to provide heating.

②Heat collection (ground pipe network + roof truss upper and lower chord pipe network)/heat release (ground pipe network + roof truss lower chord pipe network). The advantage of this control mode is that it can maximize the collection and storage of solar energy during the day and maximize the release of accumulated heat into the greenhouse at night. The daytime heat collection method is the same as the daytime heat collection method in ①; for nighttime heat dissipation, when the system detects that the temperature in the greenhouse is lower than 10°C and 2°C lower than the water temperature, the ground pipe network system is first started to accumulate water during the day through water circulation. The heat in the pool is released near the greenhouse floor to provide heating; when the ground cooling system is insufficient to maintain the internal temperature of the greenhouse, and the system detects that the temperature in the greenhouse is lower than 8°C, it starts the roof truss cooling system.

③Heat collection (upper and lower pipe network on the roof truss)/heat release (ground pipe network). This control mode is suitable for situations where the crop plants are tall and the indoor heating load at night is relatively small. Tall plants can easily form a shading effect and affect the heat collection efficiency of the ground heat collecting device. Therefore, only roof trusses are used to collect heat at this stage. The heat collection method of the roof truss is the same as that of the middle roof truss in ①. During the day, the upper and lower chord pipe networks supply water at the same time and circulate heat storage. At night, only the ground pipe network is used for heat dissipation. The heat dissipation control method is the same as ①. It is suitable for tall crops and at night. Seasons when indoor temperatures are higher.

④ Heat collection (upper and lower chord pipe network of roof truss)/heat release (lower chord pipe network of roof truss + ground pipe network). This control method is suitable for situations where the crop plants are tall and the indoor heating load is relatively large at night. Tall plants can easily form a shading effect and affect the heat collection efficiency of the ground heat collecting device. Therefore, only roof trusses are used to collect heat at this stage. Heat dissipation at night uses the method of starting the roof truss pipe network and the ground pipe network together, and the control method is the same as ②.

Claims (5)

1. The greenhouse roof truss solar heat collecting and releasing system is characterized in that a roof truss is formed by connecting a web member between an upper chord pipe and a lower chord pipe, the roof truss is fixed on east-west gable and north wall, and the roof truss top surface and a south roof are covered by transparent materials of transparent plastic films to form a sunlight greenhouse, namely the greenhouse roof truss solar heat collecting and releasing system; it is characterized in that the method comprises the steps of,

firstly, adding a ground pipe network system, an underground reservoir and a control system into a greenhouse roof truss solar heat collecting and releasing system; the heat storage device is used for heat storage in daytime and heat release at night;

secondly, dividing a greenhouse roof truss solar heat collecting and releasing system into three independent pipe network systems of a roof truss upper chord pipe network, a greenhouse lower chord pipe network and a greenhouse ground pipe network, wherein each independent pipe network system is provided with an independent water pump and can independently operate to form a ground auxiliary enhanced greenhouse roof truss solar heat collecting and releasing system; the function of winding the roof truss is adjusted to have the heat collecting function only; the heat is prevented from being easily lost through the roof;

the roof truss upper chord pipe network and the roof truss lower chord pipe network consist of an upper chord pipe, a lower chord pipe, an upper chord water supply main pipe, a lower chord water supply main pipe, an upper chord water supply branch pipe, a lower chord water supply branch pipe, a roof truss backwater main pipe, a reservoir water pump connected with the upper chord pipe network and the lower chord pipe network and corresponding independent control valves; wherein the roof truss upper chord and lower chord pipe networks are formed by: the middle of the upper chord tube (1) and the lower chord tube (2) is connected by a web member to form a roof truss, the roof truss is fixed on east-west gable and north wall (22), and the roof truss top surface and south roof are covered by transparent plastic film light-transmitting materials; the sections, close to the ground, of the upper chord tube (1) and the lower chord tube (2) are respectively connected with an upper chord tube electromagnetic control valve (3) and a lower chord tube electromagnetic control valve (4); the water supply main pipe (5) of the roof truss heat collection system is respectively connected with the upper chord pipe electromagnetic control valve (3) and the lower chord pipe electromagnetic control valve (4); the roof truss water supply main pipe is respectively connected with the upper chord pipe electromagnetic control valve (3) and the lower chord pipe electromagnetic control valve (4) through a roof truss connecting hose (6); the roof truss water supply main pipe control valve (8) and the water pressure and flow integral meter (21) are connected between the lower chord pipe electromagnetic control valve (4) and the reservoir water pump (14); the roof truss upper chord water supply main pipe electromagnetic control valve (18) and the water pressure and flow integrated meter (21) are connected between the upper chord pipe electromagnetic control valve (3) and the reservoir water pump (14); the upper chord main water supply pipe (19) of the roof truss heat collection system is connected between the upper chord pipe electromagnetic control valve (3) and the reservoir water pump (14); a reservoir water pump (14); the roof truss backwater main pipe (17) is connected with the roof truss pipe backwater port (13) and is inserted into the reservoir (15); the control box (16) is fixed on the north wall (22), and the temperature and humidity monitoring module (20) of the control system is supported below the reinforced greenhouse roof truss; the heat preservation quilt (23) is fixed on the top surface of the roof truss; the upper and lower chord tubes should be able to withstand the necessary pressure required for water circulation and the surface should be blackened to enhance the heat absorbing capacity, in addition to meeting structural requirements.

2. The ground-assisted enhanced greenhouse roof truss solar heat collection and release system of claim 1, wherein the ground pipe network system comprises a ground water main, a water return main, an inter-row branch pipe, a main control valve, a branch pipe control valve and a water pump; the ground heat dissipation main pipe control valve (7) and the water pressure and flow rate integrated meter (21) are connected between the ground backwater main pipe (9) and the reservoir water pump (14); the ground branch pipe (10) connects the ground water main pipe (11) and the ground backwater main pipe (9) into a ground pipe network, and the ground pipe network is inserted into the reservoir (15) through the ground pipe backwater port (12); the ground pipe network enhances the heat collection capacity of the whole system, and the pipe can bear the requirement of necessary water pressure except the joint.

3. The ground-assisted enhanced greenhouse roof truss solar heat collection and release system of claim 1, wherein the control system comprises: the device comprises a control box, a temperature and humidity measuring module, an electromagnetic control valve and a pipeline control valve.

4. The heat collecting and controlling method of the ground-assisted enhanced greenhouse roof truss solar heat collecting and releasing system is characterized in that the heat collecting and releasing system realizes time-sharing and sectional control, and the specific principle is as follows:

(1) In the low stage of seedling crop plants, the demand on the temperature of the surrounding environment is higher, in view of the fact, the three pipe network systems of the roof truss winding up and winding down and the ground are started in daytime to collect heat simultaneously, wherein the ground pipe network heat collection system mainly collects and accumulates part of solar radiation transmitted to the ground into a water pool, the effect of increasing the heat collection area is achieved, the demand in a special period is met, and at night, the ground pipe network heat release system is started at first to realize root heating; the released heat is partially transmitted to the whole crop canopy gradually based on the hot air floating principle, and the other part of the released heat is in contact with the soil to directly heat the root soil and improve the root ring temperature environment, so that the whole heat is utilized and is not wasted; when the temperature is low and the heat release on the ground is insufficient, the lower chord pipe network of the roof truss is started to participate in heat release, and the temperature near the growth point at the top of the crop canopy can be raised by the heat;

(2) In the growing period of crops, the resistance of the crops to the low-temperature environment is correspondingly enhanced, and the solar radiation received by the ground is reduced due to the shielding of the tall plants on the ground, so that the heat collection is mainly carried out through the upper chord pipe network and the lower chord pipe network of the roof truss in the daytime; the heat release at night is still carried out by taking the ground pipe network as priority, and under the condition of deficiency, the lower chord pipe network of the roof truss is started again to participate in the heat release;

the ground pipe network in the ground auxiliary enhancement type greenhouse roof truss solar heat collecting and releasing system enhances the heat collecting capacity of the whole system, and the problem of insufficient heat storage of the system in a specific period of crop seedling stage is solved pertinently; the combined heat release mode of the ground pipe network and the roof truss lower chord pipe network ensures that the heat release position is more reasonable, realizes the targeted heating of the root and canopy spaces of crops, and improves the utilization efficiency of the accumulated heat.

5. The heat collecting and controlling method of the ground-assisted enhanced greenhouse roof truss solar heat collecting and controlling system according to claim 4, wherein the time-sharing sectional control is as follows: in the daytime heat storage stage, when the indoor air temperature is higher than the water temperature and the temperature difference is more than or equal to 2 ℃, under the conditions that crops are low and the ground can receive solar radiation, a control water pump of a ground pipe network, an upper chord pipe network and a lower chord pipe network of a roof truss is started, solar radiation heat irradiated to the ground pipe network, the upper chord pipe network and the lower chord pipe network of the roof truss is collected and brought into an underground reservoir through the circulation flow of water in the pipe network, the water body is heated, and the heat is stored; when the difference between the indoor air temperature and the water temperature is less than 2 ℃, the operation of the heat collection system of the upper chord pipe network and the lower chord pipe network of the roof truss is stopped; in the stage of heat release at night, when the indoor air temperature is lower than the set temperature and lower than the water temperature by 2 ℃, a ground pipe network control water pump is started firstly, warm water in a pool circulates in the ground pipe network, and heat is released to an area near the ground surface, namely the root of crops, through the ground pipe network; when the root soil and the air environment are heated, the upper canopy space is gradually heated due to the floating principle of the hot air; under extreme cold weather conditions, indoor environment temperature continuously reduces, when a ground heat dissipation system is insufficient to maintain the internal temperature of a greenhouse constant, a roof truss lower chord pipe network is started to control a water pump, heat is emitted into a room through the ground pipe network and the roof truss lower chord pipe network, the temperature of the root parts and the top parts of crowns of crops is improved, and as the space between the roof truss lower chord and the upper chord and the light-transmitting surface is more than 30cm, a part of heat is effectively prevented from being directly dissipated out of the roof, and the utilization efficiency of accumulated heat is improved.