Solar phase change and soil heat storage heat pump system for agricultural greenhouse

Abstract

The utility model discloses a solar phase change and soil heat storage heat pump system for an agricultural greenhouse, which comprises a solar heat collection unit, a water source heat pump, a phase change energy storage unit, a soil energy storage unit and a control unit, and the solar heat collection unit, the phase change energy storage unit and the soil energy storage unit are connected to form a solar energy storage circulating system. The solar heat collection unit absorbs solar radiation, converts the solar radiation into heat energy and stores the heat energy in the phase change energy storage unit and the soil energy storage unit, the water source heat pump and the phase change energy storage unit are connected to form a heat pump heating system, and the water source heat pump raises the temperature to supply heat to the greenhouse at night. By means of the mode, the solar phase change and soil heat storage heat pump system for the agricultural greenhouse integrates the solar heat collection technology, the phase change heat storage technology, the soil heat storage technology and the water source heat pump technology, can increase the temperature of abundant heat in the greenhouse in the daytime and store the heat in the phase change heat storage box, and meets the requirement for increasing the temperature of the agricultural greenhouse at night. The water source heat pump is used for heating, heating can be achieved by consuming a small amount of electric energy, and energy consumption is extremely low.

Description

Technical Field

[0001] The utility model relates to the technical field of solar phase change energy storage and water source heat pump heating, in particular to a solar phase change and soil heat storage heat pump system for agricultural greenhouses. Background Art

[0002] The large-scale construction of greenhouses in the cold northern regions not only solves the supply of fresh fruits and vegetables for local residents, but also solves the diversified development of the rural economy (such as greenhouse breeding, seedling cultivation, etc.), providing strong support for the revitalization of the rural economy.

[0003] The "Encyclopedia of Chinese Agriculture: Vegetable Volume" describes the suitable production temperatures for different vegetables as follows: general vegetable crops grow slowly at 5℃~10℃; grow normally at 10℃~20℃; grow faster at 20℃~35℃; when the temperature exceeds 35℃ and is below 5℃, the growth of vegetable crops will be impaired; the suitable growth temperature is between 20℃~30℃.

[0004] Therefore, in cold northern regions, the air temperature in greenhouses must not be lower than a certain temperature (10°C) at night and in rainy, snowy and cloudy weather, which is the key to ensure the normal growth of plants. To ensure the temperature in the greenhouse, a heat source must be provided, which consumes a certain amount of energy.

[0005] At present, the main heat sources for greenhouse heating are coal-fired, gas-fired boilers and air source heat pumps. Coal-fired and gas-fired boilers consume a large amount of fossil energy and cause serious pollution to the environment. Air source heat pumps do not require heating in the high-efficiency area of ​​the greenhouse during the day, but the heating load required in the low-efficiency area at night is very large, resulting in large investment and high operating costs.

[0006] The characteristic of greenhouses is that during the day, the soil and plants absorb solar energy to generate heat, which creates a greenhouse effect in the greenhouse, with the temperature reaching 20℃ or even above 30℃; at night, due to the lack of solar energy supplement, the heat dissipation of the enclosure structure causes the temperature in the greenhouse to drop continuously. Therefore, how to move the abundant heat during the day to the night and maintain the temperature in the greenhouse at night is the key to solving the problem, which can greatly reduce energy consumption.

[0007] The existing patent document with patent announcement number CN216314321U discloses a solar phase change heat storage soil heating greenhouse heating system, but the patent has shortcomings in transferring the abundant heat of the agricultural greenhouse during the day to the evening for use:

[0008] During the night heating process in winter or when the ambient temperature is low, a large amount of electricity will be consumed due to the low evaporation temperature, resulting in increased energy consumption in the night heating process. Utility Model Content

[0009] The main technical problem solved by the utility model is to provide a solar phase change and soil heat storage heat pump system for agricultural greenhouses, which integrates solar energy collection, phase change heat storage, soil heat storage and water source heat pump technologies, and can heat up the abundant heat in the greenhouse during the day and store it in a phase change heat storage box to meet the needs of agricultural greenhouses to increase temperature at night; the water source heat pump is used to extract the heat of the phase change energy storage box, and only a small amount of electric energy is needed to raise the temperature for greenhouse heating. The energy consumption during operation is extremely low, which can greatly reduce energy consumption.

[0010] In order to solve the above technical problems, a technical solution adopted by the utility model is: to provide a solar phase change and soil thermal storage heat pump system for agricultural greenhouses, including: a solar thermal collection unit, a water source heat pump, a phase change energy storage unit, a soil energy storage unit and a control unit, the control unit is electrically connected to the solar thermal collection unit, the water source heat pump, the phase change energy storage unit and the soil energy storage unit, the solar thermal collection unit, the phase change energy storage unit and the soil energy storage unit are connected to form a solar energy storage circulation system, during the day, the solar thermal collection unit absorbs solar radiation energy and converts it into heat energy and stores it in the phase change energy storage unit and the soil energy storage unit, the water source heat pump and the phase change energy storage unit are connected to form a heat pump heating system, and at night the water source heat pump heats the greenhouse by extracting heat from the phase change energy storage unit.

[0011] In a preferred embodiment of the present invention, the soil energy storage unit includes a water distributor, a water collector and a horizontal buried tube heat exchanger, and the horizontal buried tube heat exchanger is arranged 30-60 cm below the greenhouse ground level in the horizontal direction.

[0012] The water distributor and water collector are connected at both ends of the horizontal buried tube heat exchanger, the outlet of the phase change energy storage unit is connected to the water distributor end of the soil energy storage unit, and the water collector end of the soil energy storage unit is connected to the inlet of the solar thermal collection unit.

[0013] In a preferred embodiment of the utility model, the control unit includes a controller, a first temperature sensing probe, a second temperature sensing probe, a third temperature sensing probe and a fourth temperature sensing probe, wherein the first temperature sensing probe, the second temperature sensing probe, the third temperature sensing probe and the fourth temperature sensing probe are electrically connected to the controller.

[0014] The first temperature sensing probe is placed in the solar thermal collection unit, the second temperature sensing probe is placed in the phase change energy storage unit, the third temperature sensing probe is placed in the greenhouse one meter above the ground, and the fourth temperature sensing probe is placed in the soil 20-30 cm above the ground.

[0015] In a preferred embodiment of the utility model, the control unit also includes a first circulating water pump, a second circulating water pump, a first electric valve, a second electric valve, a third electric valve, a fourth electric valve and a fifth electric valve, and the controller is electrically connected to the first electric valve, the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve, the first circulating water pump, the second circulating water pump and the water source heat pump.

[0016] In a preferred embodiment of the utility model, the outlet of the solar thermal collection unit is connected to the inlet of the first circulating water pump, the outlet of the first circulating water pump is connected to the inlet of the phase change energy storage unit through the third electric valve, and the outlet of the phase change energy storage unit is connected to the inlet of the solar thermal collection unit through the fourth electric valve;

[0017] The outlet of the phase change energy storage unit is also connected to the inlet of the soil energy storage unit, and the outlet of the soil energy storage unit is connected to the inlet of the solar thermal collection unit through a fifth electric valve;

[0018] The outlet of the first circulating water pump is also connected to the inlet of the condenser in the water source heat pump, the outlet of the evaporator in the water source heat pump is connected to the inlet of the second circulating water pump, and the outlet of the second circulating water pump is connected to the inlet of the phase change energy storage unit. The outlet of the phase change energy storage unit is connected to the inlet of the evaporator in the water source heat pump through the second electric valve, and the outlet of the condenser in the water source heat pump is connected to the inlet of the solar collector through the first electric valve.

[0019] In a preferred embodiment of the utility model, the solar thermal collection unit includes a solar thermal collector array and a connecting pipeline, the solar thermal collector array includes a plurality of solar thermal collector panels arranged in series, the solar thermal collector panel group is composed of a plurality of solar thermal collector panels connected in parallel, and the solar thermal collector panel includes a working fluid inlet end and a working fluid outlet end of a heat exchange working fluid:

[0020] The working fluid outlet end of the upper solar collector panel group is connected to the working fluid inlet end of the adjacent next solar collector panel group, the working fluid inlet end of the first solar collector panel group is connected to the system's water supply pipe, and the working fluid outlet end of the last solar collector panel group is connected to the system's return water pipe.

[0021] In a preferred embodiment of the present invention, the phase change energy storage unit comprises a phase change energy storage box, a heat exchange tube and a phase change energy storage material.

[0022] The phase change energy storage box forms an outer protective structure of the phase change energy storage unit, a heat exchange tube is arranged inside the phase change energy storage box, and a phase change energy storage material is filled in the gap between the inside of the phase change energy storage box and the outside of the heat exchange tube.

[0023] In a preferred embodiment of the utility model, the water source heat pump comprises a compressor, a water-fluorine shell and tube evaporator, a water-fluorine shell and tube condenser and a throttle valve connected in series to form a loop.

[0024] The tube-side heat exchange working medium of the water-fluorine shell and tube evaporator is fluorine, the shell-side heat exchange working medium is water, the water channel inlet end of the evaporator is connected to the working medium outlet end of the phase change energy storage unit, the water channel outlet end of the evaporator is connected to the second circulating water pump, and the second circulating water pump is connected to the working medium inlet end of the phase change energy storage unit;

[0025] The tube-side heat exchange working fluid of the water-fluorine shell and tube condenser is fluorine, and the shell-side heat exchange working fluid is water. The condenser water circuit inlet end is connected to the first circulating water pump outlet end, the working fluid outlet end of the solar thermal collection unit is connected to the first circulating water pump inlet end, and the condenser water circuit outlet end is connected to the working fluid inlet end of the solar thermal collection unit, thereby forming a circulating pipeline system.

[0026] In a preferred embodiment of the utility model, it also includes an auxiliary heat source, which is connected in parallel between the solar thermal collection unit and the phase change energy storage unit. A sixth electric valve is arranged on the connecting pipeline of the auxiliary heat source, and the sixth electric valve is electrically connected to the controller.

[0027] In a preferred embodiment of the present invention, the auxiliary heat source can be a gas water heater and an electric water heater.

[0028] The beneficial effects of the utility model are: it integrates solar energy collection, phase change heat storage, soil heat storage and water source heat pump technology into one, and can heat up the abundant heat in the greenhouse during the day and store it in the phase change heat storage box to meet the needs of nighttime warming of the agricultural greenhouse; it completes the cross-time transfer of energy, and while increasing the nighttime temperature of the agricultural greenhouse, it realizes the peak shaving and valley filling of solar energy; it uses a water source heat pump to extract the heat in the phase change energy storage unit, and only consumes a small amount of electricity to raise the temperature for greenhouse heating. The energy consumption during operation is extremely low, which can greatly reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0030] Figure 1 It is a schematic diagram of the system structure of a preferred embodiment of the solar energy phase change and soil heat storage heat pump system for agricultural greenhouses of the utility model;

[0031] Figure 2This is a control principle diagram of the solar energy phase change and soil heat storage heat pump system for agricultural greenhouses of the utility model;

[0032] Figure 3 It is a schematic diagram of the system structure of a preferred embodiment of the solar energy phase change and soil heat storage heat pump system for agricultural greenhouses of the utility model;

[0033] The markings of the components in the accompanying drawings are as follows:

[0034] 1. First electric valve, 2. Second electric valve, 3. Third electric valve, 4. Fourth electric valve, 5. Fifth electric valve, 6. Sixth electric valve, 7. First circulating water pump, 8. Second circulating water pump, 9. Auxiliary heat source, 10. Water source heat pump, 11. Phase change energy storage unit, 12. Solar thermal collection unit, 13. Horizontal buried pipe heat exchanger, 14. Water distributor, 15. Water collector. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The utility model relates to a preferred embodiment of a solar energy phase change and soil heat storage heat pump system for agricultural greenhouses, which couples solar energy collection, phase change heat storage, soil heat storage and water source heat pump technologies, realizes different operation modes by driving a circulating water pump and an electric valve, and meets the needs of nighttime warming of agricultural greenhouses.

[0038] like Figure 1-3 As shown, the solar phase change and soil thermal storage heat pump system for agricultural greenhouses includes: a solar thermal collection unit 12, a water source heat pump 10, a phase change energy storage unit 11, a soil energy storage unit and a control unit, and the control unit is electrically connected to the solar thermal collection unit 12, the water source heat pump 10, the phase change energy storage unit 11 and the soil energy storage unit.

[0039] In an exemplary embodiment, the solar thermal collection unit 12, the phase change energy storage unit 11 and the soil energy storage unit are connected to form a solar energy storage cycle system. During the day, the solar thermal collection unit 12 absorbs solar radiation energy and converts it into heat energy which is stored in the phase change energy storage unit 11 and the soil energy storage unit.

[0040] In an exemplary embodiment, the water source heat pump 10 and the phase change energy storage unit 11 are connected to form a heat pump heating system. At night, the water source heat pump 10 extracts the heat stored in the phase change energy storage unit 11 during the day to heat the greenhouse.

[0041] The water source heat pump 10 has a high operating efficiency, especially when the ambient temperature is low, such as in winter, because the water temperature is higher than the air temperature, so the water source heat pump cycle evaporation temperature and energy efficiency ratio will be improved. In this way, when the water source heat pump extracts heat from the phase change energy storage unit, only a small amount of electricity is consumed to raise the temperature for greenhouse heating. This process consumes very little energy, which can greatly reduce energy consumption.

[0042] Furthermore, the solar thermal collection unit 12 includes a solar thermal collector array and connecting pipelines, the solar thermal collector array includes a plurality of solar thermal collector panel groups arranged in series, the solar thermal collector panel group is composed of a plurality of solar thermal collector panels connected in parallel, and the solar thermal collector panel includes a working fluid inlet end and a working fluid outlet end of the heat exchange working fluid.

[0043] The working fluid outlet end of the upper solar collector panel group is connected to the working fluid inlet end of the adjacent next solar collector panel group, the working fluid inlet end of the first solar collector panel group is connected to the system's water supply pipe, and the working fluid outlet end of the last solar collector panel group is connected to the system's return water pipe.

[0044] Furthermore, the phase change energy storage unit 11 includes a phase change energy storage box, a heat exchange tube and a phase change energy storage material. The phase change energy storage box has an inlet end and an outlet end of the heat exchange medium. The phase change energy storage box forms an outer protective structure of the phase change energy storage unit. The phase change energy storage box is provided with a heat exchange tube. The phase change energy storage material is filled in the gap between the inside of the phase change energy storage box and the outside of the heat exchange tube. The phase change point of the phase change material is 20-35°C.

[0045] Furthermore, the soil energy storage unit includes a water distributor 14, a water collector 15 and a transverse buried tube heat exchanger 13. The transverse buried tube heat exchanger is horizontally arranged 30-60 cm below the greenhouse floor level. The water distributor and the water collector are connected at both ends of the transverse buried tube heat exchanger.

[0046] The soil energy storage unit is a system that uses soil as a thermal energy storage medium. The utility model mainly uses shallow soil to store solar energy during the day and release it at night to increase the temperature, thereby improving energy utilization efficiency.

[0047] Furthermore, the water source heat pump 10 includes a compressor, a water-fluorine shell and tube evaporator, a water-fluorine shell and tube condenser and a throttle valve connected in series to form a loop:

[0048] The tube-side heat exchange working medium of the water-fluorine shell and tube evaporator is fluorine, the shell-side heat exchange working medium is water, the water channel inlet end of the evaporator is connected to the working medium outlet end of the phase change energy storage unit, the water channel outlet end of the evaporator is connected to the second circulating water pump, and the second circulating water pump is connected to the working medium inlet end of the phase change energy storage unit;

[0049] The tube-side heat exchange working fluid of the water-fluorine shell and tube condenser is fluorine, and the shell-side heat exchange working fluid is water. The condenser water circuit inlet end is connected to the first circulating water pump outlet end, the working fluid outlet end of the solar thermal collection unit is connected to the first circulating water pump inlet end, and the condenser water circuit outlet end is connected to the working fluid inlet end of the solar thermal collection unit, thereby forming a circulating pipeline system.

[0050] Furthermore, the control unit includes a controller, a first temperature sensing probe, a second temperature sensing probe, a third temperature sensing probe and a fourth temperature sensing probe, the first temperature sensing probe, the second temperature sensing probe, the third temperature sensing probe and the fourth temperature sensing probe are electrically connected to the controller, the first temperature sensing probe is placed in the solar collector, the second temperature sensing probe is placed in the phase change energy storage box, the third temperature sensing probe is placed in the greenhouse one meter above the ground, and the fourth temperature sensing probe is placed on the soil 20-30 cm above the ground.

[0051] Furthermore, the control unit also includes a first circulating water pump 7, a second circulating water pump 8, a first electric valve 1, a second electric valve 2, a third electric valve 3, a fourth electric valve 4 and a fifth electric valve 5, and the controller is electrically connected to the first electric valve 1, the second electric valve 2, the third electric valve 3, the fourth electric valve 4, the fifth electric valve 5, the first circulating water pump 7, the second circulating water pump 8 and the water source heat pump 10.

[0052] In an exemplary embodiment, the outlet of the solar thermal collection unit 12 is connected to the inlet of the first circulating water pump 7, the outlet of the first circulating water pump 7 is connected to the inlet of the phase change energy storage unit 11 through the third electric valve 3, the outlet of the phase change energy storage unit 11 is connected to the inlet of the solar thermal collection unit 12 through the fourth electric valve 4, the outlet of the phase change energy storage unit 11 is also connected to the water distributor 14 end of the soil energy storage unit, and the water collector 15 end of the soil energy storage unit is connected to the inlet of the solar thermal collection unit 12 through the fifth electric valve 5.

[0053] During energy storage, the high temperature heat generated by the solar thermal collection unit 12 is first stored and cooled by the phase change energy storage unit 11, then stored and cooled by the soil energy storage unit, and then returns to the solar thermal collection unit 12, forming a thermal cycle.

[0054] Furthermore, the outlet of the first circulating water pump 7 is also connected to the inlet of the water-fluorine shell and tube condenser of the water source heat pump 10, the outlet of the water-fluorine shell and tube evaporator of the water source heat pump 10 is connected to the inlet of the second circulating water pump 8, the outlet of the second circulating water pump 8 is further connected to the inlet of the phase change energy storage unit 11, the outlet of the phase change energy storage unit 11 is connected to the inlet of the water-fluorine shell and tube evaporator of the water source heat pump 10 through the second electric valve 2, and the outlet of the water-fluorine shell and tube condenser of the water source heat pump 10 is connected to the inlet of the solar collector through the first electric valve 1.

[0055] When providing heat, the water source heat pump 10 extracts heat from the phase change energy storage tank and uses a small amount of electric energy to raise the temperature to provide heat to the greenhouse.

[0056] In the utility model, the solar phase change and soil heat storage heat pump system for agricultural greenhouses also includes an auxiliary heat source 9, which is connected in parallel between the solar heat collection unit 12 and the phase change energy storage unit 11. A sixth electric valve 6 is provided on the connecting pipeline of the auxiliary heat source 9, and the sixth electric valve 6 is electrically connected to the controller. When the phase change energy storage unit 11 cannot meet the heating needs of the water source heat pump 10, the auxiliary heat source 9 is started for auxiliary heating.

[0057] The control process of the solar phase change and soil heat storage heat pump system for agricultural greenhouses of the utility model includes three operation modes: energy storage mode, heating mode and auxiliary energy heating mode:

[0058] Assume that the core temperature of the solar collector is T b , the set temperature of the solar collector is T o (generally set to 25-35℃), the air temperature in the greenhouse is T i ,

[0059] The temperature inside the phase change energy storage box is T h , the set temperature of the phase change energy storage box is T a (generally set to 35-45℃), soil temperature is T s ,

[0060] The controller controls the start and stop of the first electric valve, the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve and the sixth electric valve (electric three-way valve), the first circulating water pump, the second circulating water pump and the heat pump according to the temperature signals of each temperature probe;

[0061] Energy storage mode:

[0062] When T b -T o>ΔT1 (where ΔT1 is the starting temperature difference set for solar thermal collection), start the first circulation water pump 7, open the third electric valve 3, open the fifth electric valve 5, close the first electric valve 1, close the fourth electric valve 4, and close the second electric valve 2. At this time, the solar thermal collector absorbs solar radiation energy and converts it into heat energy and stores it in the phase change energy storage unit and the soil. The high-temperature heat generated by the solar thermal collector is first stored and cooled in the phase change heat storage unit, and then stored and cooled in the soil and returned to the solar thermal collector, forming a thermal cycle;

[0063] When T s >T1 (where T1 is the upper limit of the soil temperature setting, such as 25°C), the fourth electric valve 4 is opened, and the fifth electric valve 5 is closed, and the heat generated by the solar collector is only used to heat the phase change energy storage unit;

[0064] When T h >T2 (where T2 is the upper temperature limit set in the phase change energy storage box, such as 45°C), turn off the first circulating water pump 7, close the third electric valve 3 and the fourth electric valve 4, and stop energy storage;

[0065] 2. Heating mode:

[0066] When T i <T3 (where T3 is the lower limit of the air temperature in the greenhouse in heating mode, such as 10°C), the first circulating water pump 7 is turned on, the second circulating water pump 8 is turned on, the first electric valve 1 is opened, the second electric valve 2 is opened, the third electric valve 3 is closed, the fourth electric valve 4 is closed, and the fifth electric valve 5 is closed. At this time, the water source heat pump 10 can heat the greenhouse by extracting heat from the phase change energy storage tank and only needs a small amount of electric energy to raise the temperature;

[0067] When T i >T4 (where T4 is the upper limit of the air temperature in the greenhouse in the heating mode, such as 15°C), turn off the first circulating water pump 6 and the second circulating water pump 7 to stop heating;

[0068] 3. Auxiliary energy heating mode

[0069] When T h When <T5 (where T5 is the lower limit of the temperature setting in the phase change heat storage tank, such as 10°C), the first circulating water pump 7 is turned on, the first electric valve 1 is opened, the sixth electric valve 6 is opened (the valve body of the sixth electric valve 6 is opened to connect to the auxiliary heat source pipeline), the second electric valve 2 is closed, the third electric valve 3 is closed, the fourth electric valve 4 is closed, the fifth electric valve 5 is closed, the second circulating water pump 8 is closed, and the auxiliary heat source 9 is turned on to supply heat to the greenhouse. The auxiliary energy can be a gas water heater and an electric water heater.

[0070] The beneficial effects of the solar energy phase change and soil heat storage heat pump system used in agricultural greenhouses are:

[0071] The technology of solar thermal collection, phase change thermal storage, soil thermal storage and water source heat pump is integrated into one, which can heat up the greenhouse during the day and store it in the phase change thermal storage tank to meet the needs of agricultural greenhouses to increase temperature at night.

[0072] The energy transfer across time is completed, which not only increases the temperature of agricultural greenhouse at night, but also realizes the peak shifting and valley filling of solar energy.

[0073] By using a water source heat pump to extract heat from the phase change energy storage unit, only a small amount of electricity is needed to raise the temperature for greenhouse heating. The energy consumption during operation is extremely low, which can greatly reduce energy consumption.

[0074] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A solar energy phase change and soil heat storage heat pump system for agricultural greenhouses, characterized in that: include: A solar thermal collection unit, a water source heat pump, a phase change energy storage unit, a soil energy storage unit and a control unit, wherein the control unit is electrically connected to the solar thermal collection unit, the water source heat pump, the phase change energy storage unit and the soil energy storage unit. The solar thermal collection unit, phase change energy storage unit and soil energy storage unit are connected to form a solar energy storage cycle system. During the day, the solar thermal collection unit absorbs solar radiation energy and converts it into heat energy which is stored in the phase change energy storage unit and the soil energy storage unit. The water source heat pump and the phase change energy storage unit are connected to form a heat pump heating system. At night, the water source heat pump heats the greenhouse by extracting heat from the phase change energy storage unit.

2. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 1 is characterized in that: The soil energy storage unit includes a water distributor, a water collector and a transverse buried heat exchanger, wherein the transverse buried heat exchanger is arranged horizontally 30-60 cm below the greenhouse ground level. The water distributor and water collector are connected at both ends of the horizontal buried tube heat exchanger, the outlet of the phase change energy storage unit is connected to the water distributor end of the soil energy storage unit, and the water collector end of the soil energy storage unit is connected to the inlet of the solar thermal collection unit.

3. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 1 is characterized in that: The control unit includes a controller, a first temperature sensing probe, a second temperature sensing probe, a third temperature sensing probe and a fourth temperature sensing probe, wherein the first temperature sensing probe, the second temperature sensing probe, the third temperature sensing probe and the fourth temperature sensing probe are electrically connected to the controller. The first temperature sensing probe is placed in the solar thermal collection unit, the second temperature sensing probe is placed in the phase change energy storage unit, the third temperature sensing probe is placed in the greenhouse one meter above the ground, and the fourth temperature sensing probe is placed in the soil 20-30 cm above the ground.

4. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 3 is characterized in that: The control unit also includes a first circulating water pump, a second circulating water pump, a first electric valve, a second electric valve, a third electric valve, a fourth electric valve, a fifth electric valve and a sixth electric valve, and the controller is electrically connected to the first electric valve, the second electric valve, the third electric valve, the fourth electric valve, the fifth electric valve, the sixth electric valve, the first circulating water pump, the second circulating water pump and the water source heat pump.

5. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 4 is characterized in that: The outlet of the solar thermal collection unit is connected to the inlet of the first circulating water pump, the outlet of the first circulating water pump is connected to the inlet of the phase change energy storage unit through the third electric valve, and the outlet of the phase change energy storage unit is connected to the inlet of the solar thermal collection unit through the fourth electric valve; The outlet of the phase change energy storage unit is also connected to the inlet of the soil energy storage unit, and the outlet of the soil energy storage unit is connected to the inlet of the solar thermal collection unit through a fifth electric valve; The outlet of the first circulating water pump is also connected to the inlet of the condenser in the water source heat pump, the outlet of the evaporator in the water source heat pump is connected to the inlet of the second circulating water pump, and the outlet of the second circulating water pump is connected to the inlet of the phase change energy storage unit. The outlet of the phase change energy storage unit is connected to the inlet of the evaporator in the water source heat pump through the second electric valve, and the outlet of the condenser in the water source heat pump is connected to the inlet of the solar collector through the first electric valve.

6. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 5 is characterized in that: The solar thermal collection unit includes a solar thermal collector array and connecting pipelines. The solar thermal collector array includes a plurality of solar thermal collector panels arranged in series. The solar thermal collector panel group is composed of a plurality of solar thermal collector panels connected in parallel. The solar thermal collector panel includes a working medium inlet end and a working medium outlet end of a heat exchange working medium: The working fluid outlet end of the upper solar collector panel group is connected to the working fluid inlet end of the adjacent next solar collector panel group, the working fluid inlet end of the first solar collector panel group is connected to the system's water supply pipe, and the working fluid outlet end of the last solar collector panel group is connected to the system's return water pipe.

7. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 5, characterized in that: The phase change energy storage unit comprises a phase change energy storage box, a heat exchange tube and a phase change energy storage material. The phase change energy storage box forms an outer protective structure of the phase change energy storage unit, a heat exchange tube is arranged inside the phase change energy storage box, and a phase change energy storage material is filled in the gap between the inside of the phase change energy storage box and the outside of the heat exchange tube.

8. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 5, characterized in that: The water source heat pump comprises a compressor, a water-fluorine shell and tube evaporator, a water-fluorine shell and tube condenser and a throttle valve connected in series to form a loop. The tube-side heat exchange working medium of the water-fluorine shell and tube evaporator is fluorine, the shell-side heat exchange working medium is water, the water channel inlet end of the evaporator is connected to the working medium outlet end of the phase change energy storage unit, the water channel outlet end of the evaporator is connected to the second circulating water pump, and the second circulating water pump is connected to the working medium inlet end of the phase change energy storage unit; The tube-side heat exchange working fluid of the water-fluorine shell and tube condenser is fluorine, and the shell-side heat exchange working fluid is water. The condenser water circuit inlet end is connected to the first circulating water pump outlet end, the working fluid outlet end of the solar thermal collection unit is connected to the first circulating water pump inlet end, and the condenser water circuit outlet end is connected to the working fluid inlet end of the solar thermal collection unit, thereby forming a circulating pipeline system.

9. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 5, characterized in that: It also includes an auxiliary heat source, which is connected in parallel between the solar thermal collection unit and the phase change energy storage unit. A sixth electric valve is arranged on the connecting pipeline of the auxiliary heat source, and the sixth electric valve is electrically connected to the controller.

10. The solar energy phase change and soil heat storage heat pump system for agricultural greenhouses according to claim 9, characterized in that: The auxiliary heat source can be a gas water heater or an electric water heater.

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