Energy flow control system and control method for photovoltaic greenhouse heat recovery

Abstract

The application discloses an energy flow control system and control method for photovoltaic greenhouse heat recovery, and belongs to the technical field of solar energy utilization, comprising a photovoltaic power generation unit, the photovoltaic power generation unit is used for absorbing solar energy and providing electricity for a greenhouse; a heat recovery unit, the heat recovery unit is electrically connected with the photovoltaic power generation unit, the heat recovery unit is used for refrigeration and cold storage and / or heating and heat storage; a storage and utilization energy unit, the storage and utilization energy unit is connected with the heat recovery unit in parallel through a pipeline, and the storage and utilization energy unit is used for heat exchange between the greenhouse and the heat recovery unit. The application maximizes the utilization of solar energy resources, matches the power generation capacity of the photovoltaic module with the power consumption of the cold / heat load of the greenhouse, reforms the heat recovery unit, realizes stable work of the refrigeration and cold storage system and the heating and heat supply system, improves the system efficiency, improves the comprehensive energy utilization rate, and reduces the cost.

Description

Technical Field

[0001] This invention belongs to the field of solar energy utilization technology, specifically relating to an energy flow control system and control method for heat recovery in photovoltaic greenhouses. Background Technology

[0002] With the development of modern agriculture, greenhouse systems have developed rapidly because they are less affected by the environment and can provide a stable and controllable environment for the growth of cultivated crops. From the perspective of environmental awareness, the best way to solve the energy and environmental problems caused by the use of greenhouse systems is to use photovoltaic energy to drive the operation of heat recovery units. However, due to the intermittent nature of solar irradiance, it is impossible to store the cold or heat generated by solar energy using the sensible or latent heat of the material. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides an energy flow control system and method for heat recovery in photovoltaic greenhouses, employing the following technical solution:

[0004] An energy flow control system for heat recovery in a photovoltaic greenhouse includes:

[0005] A photovoltaic power generation unit, which is used to absorb solar energy and provide electricity for the greenhouse;

[0006] A heat recovery unit is electrically connected to the photovoltaic power generation unit, and the heat recovery unit is used for cooling and / or heating and storage.

[0007] An energy storage unit is connected in parallel with the heat recovery unit via pipelines. The energy storage unit is used to enable heat exchange between the greenhouse and the heat recovery unit.

[0008] Furthermore, the photovoltaic power generation unit includes a photovoltaic module and an inverter controller; the photovoltaic module is connected to the heat recovery unit through the inverter controller, and the inverter controller is electrically connected to both the photovoltaic module and the heat recovery unit.

[0009] Furthermore, the heat recovery unit includes a variable frequency compressor 3, a gas-liquid separator, an evaporator, a second condenser, and a first condenser connected in sequence through pipelines; the variable frequency compressor 3 is electrically connected to the inverter controller; and the energy storage unit is connected in parallel across the two ends of the evaporator.

[0010] Furthermore, the energy storage unit includes a hot water tank, a cold water tank, and a fan; the cold water tank is fitted outside the evaporator, the outlet of the evaporator is connected to the gas-liquid separator via a first pipeline, the inlet of the evaporator is connected to the outlet of the second condenser via a second pipeline, and a throttling valve is installed on the second pipeline; the outlet and inlet of the cold water tank are connected via a third pipeline, the third pipeline is located inside the fan, and a circulation pump II is installed on the third pipeline;

[0011] The first outlet of the hot water tank is connected to the first inlet of the first condenser via a fourth pipe, and the first inlet of the hot water tank is connected to the first outlet of the first condenser via a fourth pipe. A circulation pump I is installed on the fourth pipe. The second outlet of the hot water tank and the second inlet of the hot water tank are connected via a fifth pipe, which is located inside the fan and is equipped with a circulation pump III. The second inlet of the first condenser is connected to the variable frequency compressor 3 via a sixth pipe, and the second outlet of the first condenser is connected to the inlet of the second condenser via a seventh pipe. The seventh pipe and the first pipe are connected via a four-way reversing valve.

[0012] Furthermore, an energy flow control method for heat recovery in a photovoltaic greenhouse employs the energy flow control system for heat recovery in a photovoltaic greenhouse as described in any of the above claims, the method comprising:

[0013] When the irradiance reaches the starting condition of the variable frequency compressor, the variable frequency compressor drives the refrigerant to flow to the first condenser for heating and heat storage, and then flows through the second condenser and the expansion valve to the evaporator. The refrigerant returns to the variable frequency compressor through the evaporator and the gas-liquid separator. At this time, the evaporator of the refrigeration system is in a state of cooling and storing cold at the same time. When the temperature of the greenhouse fed by the temperature sensor has not yet reached the temperature required by the crops, the heat recovery unit controller starts the circulation pump II to circulate the cold water tank to the fan in the greenhouse to exchange heat with the hot air in the greenhouse, completing the mode of storing cold while supplying cold, which plays a role in reducing the temperature in the greenhouse.

[0014] When the temperature sensor inside the greenhouse indicates that the temperature is lower than the temperature required by the crops, the heat stored in the first condenser of the daytime heating system is used to activate the circulation pump III in the energy storage unit according to the greenhouse's heat demand. The heat in the hot water tank is then transferred to the greenhouse through the fan to maintain the temperature required by the greenhouse crops, ensuring uninterrupted heating until the irradiance reaches the starting condition of the variable frequency compressor, at which point a new cycle begins.

[0015] Beneficial effects:

[0016] This invention maximizes the use of solar energy resources, matches the power generation of photovoltaic modules with the power consumption of greenhouse cooling / heating loads, modifies the heat recovery unit, and enables the refrigeration and cold storage system and heating system to operate stably, thereby improving system efficiency, enhancing the overall energy utilization rate, and reducing costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the energy flow control system for heat recovery in a photovoltaic greenhouse according to the present invention;

[0018] Among them, 1. Photovoltaic module; 2. Inverter controller; 3. Variable frequency compressor; 4. First condenser; 5. Four-way reversing valve; 6. Second condenser; 7. Throttling valve; 8. Evaporator; 9. Gas-liquid separator; 10. Hot water tank; 11. Cold water tank; 12. Circulating pump II; 13. Circulating pump III; 14. Fan; 15. Circulating pump I. Detailed Implementation

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below.

[0020] Example 1

[0021] Reference Figure 1 An energy flow control system for heat recovery in a photovoltaic greenhouse, comprising:

[0022] A photovoltaic power generation unit, which is used to absorb solar energy and provide electricity for the greenhouse;

[0023] A heat recovery unit is electrically connected to the photovoltaic power generation unit, and the heat recovery unit is used for cooling and / or heating and storage.

[0024] An energy storage unit is connected in parallel with the heat recovery unit via pipelines. The energy storage unit is used to enable heat exchange between the greenhouse and the heat recovery unit.

[0025] The heat recovery unit and the energy storage unit are both located inside the greenhouse, which is equipped with temperature sensors. These sensors measure the temperature inside the greenhouse and transmit the measured temperature information to the energy flow control system, enabling the system to execute different commands and perform different functions.

[0026] Through the above technical solution, based on the growth needs of crops in the greenhouse, the number and connection method of photovoltaic modules 1 are selected to ensure that the power generation of the solar power system is well matched with the power consumption of the greenhouse's cooling / heating load. The energy storage and utilization unit can realize the function of storing and using energy at the same time. Based on the temperature feedback in the greenhouse, it can realize the automatic switching between cooling mode and heating mode through intelligent control, avoiding the disadvantages of the greenhouse being easily affected by the environment, and providing a stable and controllable environment for the growth of cultivated crops.

[0027] In this embodiment, the photovoltaic power generation unit includes a photovoltaic module 1 and an inverter controller 2; the photovoltaic module 1 is connected to the heat recovery unit through the inverter controller 2, and the inverter controller 2 is electrically connected to both the photovoltaic module 1 and the heat recovery unit.

[0028] Among them, inverter controller 2 is selected as an inverter controller with maximum power point.

[0029] Through the above technical solution, the heat recovery unit's operation control strategy ensures that the DC power generated by photovoltaic module 1 during the day flows through inverter controller 2 with maximum power point tracking, guaranteeing that photovoltaic module 1 always operates at its maximum power point and that the output power remains at its maximum.

[0030] In this embodiment, the heat recovery unit includes a variable frequency compressor 3, a gas-liquid separator 9, an evaporator 8, a second condenser 6, and a first condenser 4 connected in sequence through pipelines; the variable frequency compressor 3 is electrically connected to the inverter controller 2; and the energy storage unit is connected in parallel across the two ends of the evaporator 8.

[0031] In this embodiment, the energy storage unit includes a hot water tank 10, a cold water tank 11, and a fan 14. The cold water tank 11 is fitted outside the evaporator 8. The outlet of the evaporator 8 is connected to the gas-liquid separator 9 via a first pipeline, and the inlet of the evaporator 8 is connected to the outlet of the second condenser 6 via a second pipeline. A throttling valve 7 is installed on the second pipeline. The outlet and inlet of the cold water tank 11 are connected via a third pipeline. The third pipeline is located inside the fan 14, and a circulation pump II 12 is installed on the third pipeline.

[0032] The first outlet of the hot water tank 10 is connected to the first inlet of the first condenser 4 via a fourth pipe, and the first inlet of the hot water tank 10 is connected to the first outlet of the first condenser 4 via a fourth pipe. A circulation pump I 15 is installed on the fourth pipe. The second outlet of the hot water tank 10 and the second inlet of the hot water tank 10 are connected via a fifth pipe, which is located inside the fan 14 and is equipped with a circulation pump III 13. The second inlet of the first condenser 4 is connected to the variable frequency compressor 3 via a sixth pipe, and the second outlet of the first condenser 4 is connected to the inlet of the second condenser 6 via a seventh pipe. The seventh pipe and the first pipe are connected via a four-way reversing valve 5.

[0033] The first condenser 4 is preferably a plate condenser, and the second condenser 6 is preferably an air-cooled condenser.

[0034] Through the above technical solution, the plate condenser and the air-cooled condenser exchange heat with water and air respectively; the evaporator 8 is located in the water-filled cold water tank 11; the dual functions of refrigeration, cold storage, heating and heat storage are all integrated into the solar-driven heat recovery unit. The four-way reversing valve 5 can also realize the automatic switching between individual refrigeration and individual heating, which improves the practicality of the system and realizes the utilization of multiple heat sources.

[0035] The evaporator 8 is placed in the cold water tank 11, and the plate condenser stores hot water in the hot water tank 10 through the circulating pump I 15. It can simultaneously achieve the dual functions of cooling, cold storage, heating and heat storage. The four-way reversing valve 5 can switch between cooling and cold storage and heating and heat storage functions separately.

[0036] Example 2

[0037] An energy flow control method for heat recovery in photovoltaic greenhouses, employing the energy flow control system for heat recovery in photovoltaic greenhouses provided in Example 1, includes:

[0038] When the irradiance reaches the starting condition of the variable frequency compressor 3, the variable frequency compressor 3 drives the refrigerant to flow to the first condenser 4 for heating and heat storage, and then flows through the second condenser 6 and the throttle valve 7 to the evaporator 8. The refrigerant returns to the variable frequency compressor 3 through the evaporator 8 and the gas-liquid separator 9. At this time, the evaporator 8 of the refrigeration system is in a state of simultaneous cooling and cold storage. When the temperature of the greenhouse fed by the temperature sensor has not yet reached the temperature required by the crops, the heat recovery unit controller starts the circulation pump II 12 to circulate the cold energy in the cold water tank 11 to the fan 14 in the greenhouse to exchange heat with the hot air in the greenhouse, thus completing the simultaneous cold storage and cooling mode and reducing the temperature in the greenhouse.

[0039] When the temperature sensor inside the greenhouse is lower than the temperature required by the crops, the heat stored in the first condenser of the daytime heating system is used to activate the circulation pump Ⅲ13 in the energy storage unit according to the heating demand of the greenhouse. The heat in the hot water tank 10 is transferred to the greenhouse through the fan 14 to maintain the temperature required by the greenhouse crops and ensure uninterrupted heating of the greenhouse until the irradiance reaches the starting condition of the variable frequency compressor 3, at which point a new cycle begins.

[0040] Example 3

[0041] Based on Example 2, this embodiment takes a crop temperature of 15-28℃ as an example. The specific energy flow control method for the energy flow control system used in photovoltaic greenhouse heat recovery is as follows:

[0042] During the day, when the irradiance reaches the starting conditions of the variable frequency compressor 3 system, the variable frequency compressor 3 drives the refrigerant to flow to the plate condenser for heating and heat storage, and then flows through the air-cooled condenser and the expansion valve 7 to the evaporator. The refrigerant returns to the variable frequency compressor 3 through the evaporator 8 and the gas-liquid separator 9. At this time, the evaporator 8 of the refrigeration system is in a state of cooling and storing cold at the same time. As the solar irradiance gradually increases, the temperature inside the greenhouse will also gradually rise. At this time, the temperature fed back by the temperature sensor in the greenhouse has not yet reached the temperature range of 15-28℃ required by the crops. The heat recovery unit controller starts the circulation pump II 12 to circulate the cold energy in the cold water tank 11 to the fan 14 in the greenhouse to exchange heat with the hot air in the greenhouse, completing the mode of storing cold while supplying cold, which plays a role in reducing the temperature inside the greenhouse.

[0043] When the temperature sensor in the greenhouse reports a temperature below 28°C, the circulating pump II12 and the fan 14 stop operating. As the solar irradiance gradually decreases, the heat recovery unit operates continuously until the solar irradiance can no longer drive the variable frequency compressor 3 system. By adopting intelligent on-demand allocation methods, energy waste is reduced.

[0044] When the solar irradiance is low or there is no sun at night, and the temperature sensor inside the greenhouse reports a temperature below 15°C, the heat stored in the plate condenser of the daytime heating system is used to activate the circulation pump Ⅲ13 in the energy storage unit according to the greenhouse's heat demand. The heat in the hot water tank 10 is transferred to the greenhouse through the fan 14 to maintain the temperature required for the greenhouse crops, ensuring uninterrupted heating until the irradiance reaches the starting condition of the variable frequency compressor 3 system or when the sun comes out, at which point a new cycle begins.

[0045] In this embodiment, the first condenser 4 is preferably a plate condenser, and the second condenser 6 is preferably an air-cooled condenser.

[0046] Compared to traditional grid-driven cold storage or heating systems, the new environmentally friendly solar cooling / heating technology is of greater significance. The photovoltaic greenhouse heat recovery energy flow control system can achieve the dual functions of cooling, cold storage, heating, and heating, reducing the capacity of power distribution, cooling, and heating units, improving operating efficiency, and reducing operating costs, thus having excellent economic and social benefits.

[0047] The present invention provides an energy flow control system and control method for heat recovery in photovoltaic greenhouses. To ensure the reliable operation of the photovoltaic power generation unit, heat recovery unit and energy storage unit, the heat recovery unit is optimized and modified. Based on the temperature feedback inside the greenhouse, the energy storage unit can realize the function of storing and using energy at the same time through intelligent regulation, automatically switching between cooling mode and heating mode, avoiding the disadvantages of the greenhouse being easily affected by the environment, and providing a stable and controllable environment for the growth of cultivated crops.

[0048] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An energy flow control system for photovoltaic greenhouse heat recovery, characterized by, The application relates to a photovoltaic greenhouse heat recovery energy flow control system. The photovoltaic power generation unit is used for absorbing solar energy and providing electric power for a greenhouse; a heat recovery unit is electrically connected with the photovoltaic power generation unit, and the heat recovery unit is used for refrigeration and cold storage and / or heat storage; and a storage energy unit is connected with the heat recovery unit in parallel through pipelines, and the storage energy unit is used for heat exchange between the greenhouse and the heat recovery unit. The photovoltaic power generation unit comprises a photovoltaic assembly and an inverter controller; the photovoltaic assembly is connected with the heat recovery unit through the inverter controller, and the inverter controller is electrically connected with the photovoltaic assembly and the heat recovery unit. The heat recovery unit comprises a variable frequency compressor, a gas-liquid separator, an evaporator, a second condenser and a first condenser which are sequentially connected through pipelines; the variable frequency compressor is electrically connected with the inverter controller; and the storage energy unit is connected with the evaporator. The storage energy unit comprises a hot water tank, a cold water tank and a fan; the cold water tank is sleeved on the evaporator; the outlet of the evaporator is connected with the gas-liquid separator through a first pipeline; the inlet of the evaporator is connected with the outlet of the second condenser through a second pipeline; a throttling valve is arranged on the second pipeline; the outlet and the water inlet of the cold water tank are connected through a third pipeline; the third pipeline is arranged in the fan, and a circulating pump II is arranged on the third pipeline; a first outlet of the hot water tank is connected with a first inlet of the first condenser through a fourth pipeline; a first inlet of the hot water tank is connected with a first outlet of the first condenser through a fourth pipeline; a circulating pump I is arranged on the fourth pipeline; a second outlet of the hot water tank and a second water inlet of the hot water tank are connected through a fifth pipeline; the fifth pipeline is arranged in the fan, and a circulating pump III is arranged on the fifth pipeline; a second inlet of the first condenser is connected with the variable frequency compressor through a sixth pipeline; and a second outlet of the first condenser is connected with an inlet of the second condenser through a seventh pipeline. The seventh pipeline and the first pipeline are connected through a four-way reversing valve.

2. A method for energy flow control for photovoltaic greenhouse heat recovery, characterized by, The application further discloses a method for controlling the photovoltaic greenhouse heat recovery energy flow control system. When the irradiance reaches the variable frequency compressor starting condition, the variable frequency compressor drives the refrigeration working medium to flow to the first condenser to store heat, and then sequentially flows through the second condenser and the throttling valve to reach the evaporator; the working medium returns to the variable frequency compressor through the evaporator and the gas-liquid separator; when the temperature feedback by the temperature sensor of the greenhouse has not reached the required temperature of crops, the heat recovery unit controller starts the circulating pump II to circulate the cold energy in the cold water tank to the fan in the greenhouse and the hot air in the greenhouse to perform the cold storage and cooling supply mode, thereby reducing the temperature in the greenhouse. When the temperature feedback by the temperature sensor in the greenhouse is lower than the temperature required by the crops, the heat stored by the first condenser of the daytime heating system is needed, the circulating pump III in the energy storage and utilization unit is started according to the heat demand of the greenhouse at any time, the heat in the hot water tank is transmitted to the greenhouse through the fan, the required temperature of the crops in the greenhouse is maintained, the heating of the greenhouse is uninterrupted, and until the irradiance reaches the starting condition of the variable frequency compressor, a new cycle is started.

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