Greenhouse heat supply system and heat supply control method thereof

Abstract

The invention discloses a greenhouse heat supply system and a heat supply control method thereof.The greenhouse heat supply system comprises a same-path phase change heat storage and release device, a first air duct, a second air duct, a third air duct, a three-way connector, a heat collector and an electric control device, a first connector of the three-way connector is connected with an air outlet of the same-path phase change heat storage and release device, and a second connector of the three-way connector is connected with the first air duct; the first air channel is connected with an air inlet of the heat collector, an air outlet of the heat collector is connected with an air inlet of the same-path phase change heat storage and release device through the second air channel, the second air channel is provided with a circulating fan and a second air door, and a third connector of the three-way connector is connected with the third air channel which is connected with the heat release port. And a resistance heater is arranged on an air outlet of the same-path phase change heat storage and release device. According to the greenhouse heat supply system and the heat supply control method thereof, the problem that in the prior art, the effective heat release rate of phase change heat storage is low can be solved, meanwhile, free switching between heat storage and heat release can be achieved, and the greenhouse heat supply system and the heat supply control method have the advantage of being small in heat storage volume.

Description

Technical Field

[0001] The present invention relates to the technical field of solar energy equipment, and in particular to a greenhouse heating system and a heating control method thereof. Background Art

[0002] As an important facility in agricultural production, the greenhouse's anti-seasonal and anti-regional functional characteristics make it provide a suitable microclimate environment for winter cultivation of horticultural crops. Greenhouse heating has always been a key problem that has troubled growers, especially in northern China, and has even affected the healthy development of the facility industry. Greenhouse heating methods include hot water heating, hot air heating, steam heating, electric heating, radiation heating, and fuel combustion heating. Because the above-mentioned greenhouse heating methods have problems such as high energy consumption, poor heating temperature stability, environmental pollution, and high costs, the development and utilization of clean new energy has always been a hot topic in the field of facility horticulture.

[0003] Since solar heating cannot meet the load heating demand in cloudy and snowy days, nights and other conditions without the sun, in the existing technology, a cascade heat storage body is used to store heat energy on the basis of solar energy to achieve the purpose of stable supply of load heat energy. Greenhouse solar heating came into being to meet the growth needs of greenhouse plants in different regions and different climatic conditions. It can reduce the energy consumed and pollutant gases emitted during heating on cloudy and snowy days and nights, thereby achieving the effect of energy saving and emission reduction.

[0004] Greenhouse solar thermal storage heating is a technology that uses solar collectors to collect solar radiation and convert it into thermal energy for thermal storage and heating. The solar thermal storage heating system uses solar collectors to collect solar radiation and convert it into thermal energy, using fluid as the heat transfer medium and solid or liquid as the heat storage medium. The heat is stored through sensible heat or latent heat, and then sent to the heat-demanding place through the heat dissipation components for heating. The existing solar heating system is generally composed of solar collectors, thermal storage heaters, connecting pipes, auxiliary heat sources and control systems.

[0005] At present, greenhouses have been seen using solar energy collection and heat release devices for heating, but the effect of solar energy collection and heat supply devices is not ideal. There are two forms of existing greenhouse solar energy storage and heat supply. One is to use solid as a heat storage medium to store the remaining heat after the greenhouse is heated by solar energy during the day. Its main function is to balance the temperature of the greenhouse and absorb excess heat to release it when the heat in the greenhouse decreases at night; the other is to use solid or liquid as a heat storage medium to convert the solar radiation energy outside the greenhouse during the day into thermal energy storage and heating through heat collection. There are two ways to perform the thermal energy storage and heating function. One is a heat collection and heat release method that integrates solar energy collection and phase change, and the other is a heat collection and heat release method using a solar water heater.

[0006] In summary, the existing solar heating systems have the following problems: 1. The excess heat storage equipment uses a heat storage sand layer or a thin layer of inorganic phase change plate on the back wall of the greenhouse. The main problems are small heat storage, difficult automatic control, and inability to meet the greenhouse heat demand; 2. Outdoor daytime solar collection and heating equipment includes two types: integrated solar energy collection and release equipment and solar water heaters. The integrated solar energy collection and release equipment has the disadvantages of small heat storage, serious heat loss when installed outdoors, and little effective heat release. When the solar water heater meets a certain amount of heat, there are problems such as large heat storage body volume, large footprint, and complex heat exchange equipment. Summary of the invention

[0007] The purpose of the present invention is to provide a solar energy phase change heat storage and release type greenhouse heating system and a heating control method thereof, so as to solve the problems existing in the prior art such as large volume and space of heat storage body, small heat storage capacity, serious heat loss, little effective heat release of phase change heat storage, and difficult automatic control.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A greenhouse heating system of the present invention comprises a phase-changing heat storage and release device, a first air duct, a second air duct, a third air duct, a three-way interface, a heat collector and an electronic control device, wherein the first interface of the three-way interface is connected to the air outlet of the phase-changing heat storage and release device, the second interface of the three-way interface is connected to the first air duct, the first air duct is connected to the air inlet of the heat collector, the first air duct is provided with a first damper, the air outlet of the heat collector is connected to the air inlet of the phase-changing heat storage and release device through the second air duct, and the second air duct A circulating fan and a second damper are arranged on the three-way interface, the third interface of the three-way interface is connected to the third air duct, the third air duct is connected to the heat release port, the third air duct is provided with a third damper, and a resistance heater is arranged on the air outlet of the same-path phase change heat storage device, and the electronic control device is electrically connected to the circulating fan, the first damper, the second damper, the third damper and the resistance heater respectively, and is used to control the opening and closing of the circulating fan, the first damper, the second damper, the third damper and the resistance heater.

[0010] Preferably, the same-path phase-change heat storage and release device comprises a container body, finned heat exchange tubes and a filling medium, a filling port is provided on the top of the container body, a plurality of finned heat exchange tubes are distributed in the container body, and the filling medium is injected into the container body through the filling port.

[0011] Preferably, the filling medium is paraffin.

[0012] Preferably, the container body is a cylinder rolled from a steel plate, and steel plate plugs are respectively provided at both ends of the cylinder, and the steel plate plugs are used to fix the fin heat exchange tube placed in the container body.

[0013] Preferably, it also includes solar energy and resistance heating devices, which provide working heat energy for the greenhouse heating system.

[0014] Preferably, there are multiple heat release ports.

[0015] Preferably, the collector is a solar collector.

[0016] The present invention also provides a heating control method for a greenhouse heating system, using the greenhouse heating system, the method comprising:

[0017] When storing heat, the circulating fan transports the hot air in the collector through the second air duct and the second air door to the finned heat exchange tubes of the phase change heat storage and release device on the same path for heat storage;

[0018] When releasing heat, the circulating fan transports the hot air in the finned heat exchange tube of the phase change heat storage and release device in the same path through the third air duct and the third air door to the greenhouse for heat release;

[0019] When the air heat in the finned heat exchange tube of the same-path phase-change heat storage device is lower than the set value, the electronic control device opens the first damper, and the circulating fan inputs the air in the finned heat exchange tube into the collector through the first air duct for heating, and then opens the second damper to return the air to the finned heat exchange tube;

[0020] When solar energy is insufficient on cloudy and snowy days, the air in the finned heat exchange tubes is heated by a resistance heater and then released into the greenhouse to provide the heat needed by the greenhouse.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are:

[0022] The greenhouse heating system and heating control method of the present invention use a circulating fan to send the air heated by the collector through a connecting air duct to the phase change heat storage and release device on the same path for heat exchange to provide greenhouse heat, which can solve the problem of low effective heat release rate of phase change heat storage in the prior art; and by setting a plurality of dampers, free switching between heat storage and heat release can be achieved.

[0023] In addition, the greenhouse heating system and the heating control method thereof of the present invention also have the following advantages:

[0024] 1. The phase-change heat storage and release device used in the present invention is a partition-type heat exchanger, and the heat exchange tube is provided with metal fins. The tube and its fins divide the heat storage material in the heat collection pool, and the stored heat is easily released, so that the effective heat release rate of the phase-change heat storage is significantly improved;

[0025] 2. The present invention uses the same air duct to complete heat storage and release, and adopts an electronic control device to implement a hot air circulation heat storage mode during the day and a cold air heating circulation heating mode at night, thereby simplifying the automatic control process;

[0026] 3. The present invention uses heat storage material (paraffin) to store heat, which can increase the heat storage capacity while reducing the heat storage space. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a structural schematic diagram of the greenhouse heating system of the present invention;

[0029] Figure 2 It is a front view of a same-path phase-change heat storage and release device in a greenhouse heating system of the present invention;

[0030] Figure 3 It is a side view of the same-path phase-change heat storage and release device in the greenhouse heating system of the present invention.

[0031] Explanation of the accompanying drawings: 1-container body, 2-steel plate sealing, 3-air inlet, 4-filling port, 5-aluminum plate bracket, 6-fin heat exchange tube, 7-filling medium, 8-collector, 9-greenhouse, 10-same-path phase change heat storage and release device, 11-circulating fan, 12-second air gate, 13-third air gate, 14-first air gate, 15-heat release port, 16-first air duct, 17-electric control device, 18-resistance heater, 19-second air duct, 20-third air duct. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0033] In the description of the present invention, it should be understood that the terms "length", "width", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0036] Example 1

[0037] like Figure 1 As shown, the greenhouse heating system of this embodiment 1 includes a same-path phase-change heat storage and release device 10, a first air duct 16, a second air duct 19, a third air duct 20, a circulating fan 11, a first air gate 14, a second air gate 12, a third air gate 13, a resistance heater 18, a heat release port 15 and a collector 8, wherein the air outlet of the same-path phase-change heat storage and release device 10 is connected to the air inlet 3 of the collector 8 through the first air duct 16, and the air outlet of the collector 8 is connected to the air inlet 3 of the same-path phase-change heat storage and release device 10 through the second air duct 19. Preferably, the collector 8 is a solar collector.

[0038] Furthermore, the circulating fan 11 and the second damper 12 are both arranged on the second air duct 19, a resistance heater 18 is arranged on the air outlet of the same-path phase-change heat storage and release device 10, the first damper 14 is arranged on the first air duct 16, and the air outlet of the same-path phase-change heat storage and release device 10 is also connected to the heat release port 15 through the third air duct 20. Preferably, the third damper 13 is a three-way damper, and the number of the heat release ports 15 is multiple.

[0039] Preferably, the greenhouse heating system further comprises a three-way interface, a first interface of the three-way interface is connected to the air outlet of the same-path phase-change heat storage device 10, a second interface of the three-way interface is connected to the first air duct 16, and a third interface of the three-way interface is connected to the third air duct 20. That is, the air outlet of the same-path phase-change heat storage device 10, the first air duct 16 and the third air duct 20 are connected through a three-way interface.

[0040] like Figure 2 , Figure 3 As shown, the same-path phase-change heat storage and release device 10 includes finned heat exchange tubes 6, a filling port 4, a filling medium 7 and a container body 1. The finned heat exchange tubes 6 are distributed in the container body 1, and the filling medium 7 is injected into the container body 1 through the filling port 4. Preferably, the filling medium 7 is paraffin, and the number of the finned heat exchange tubes 6 is multiple.

[0041] In order to solve the problem of difficult automatic control in the prior art, the greenhouse heating system of this embodiment 1 also includes an electronic control device 17, which is electrically connected to the circulation fan 11, the first damper 14, the second damper 12, the third damper 13 and the resistance heater 18, respectively, and is used to control the opening and closing of the circulation fan 11, the first damper 14, the second damper 12, the third damper 13 and the resistance heater 18.

[0042] In addition, the greenhouse heating system of this embodiment 1 also includes a solar energy and resistance heating device for providing working heat energy for the greenhouse heating system. Optionally, the solar energy heating device can be replaced by a municipal electricity heating device according to actual needs.

[0043] The greenhouse heating system of this embodiment 1 can solve the problems existing in the prior art such as large volume and space of heat storage bodies, small heat storage capacity, serious heat loss, little effective heat release of phase change heat storage, and difficulty in automatic control.

[0044] Example 2

[0045] The heating control method of the greenhouse heating system of the second embodiment adopts the greenhouse heating system, and the method comprises:

[0046] When storing heat, the circulating fan 11 transports the hot air in the heat collector 8 through the second air duct 19 and the second air door 12 to the fin heat exchange tube 6 of the same-path phase-change heat storage and release device 10 for heat storage;

[0047] When releasing heat, the circulating fan 11 transports the hot air in the finned heat exchange tube 6 of the phase-change heat storage and release device 10 through the third air duct 20 and the third air door 13 to the greenhouse 9 for heat release;

[0048] When the air heat in the finned heat exchange tube 6 of the same-path phase-change heat storage and release device 10 is lower than the set value, the electronic control device 17 opens the first damper 14, and the circulating fan 11 inputs the air in the finned heat exchange tube 6 into the collector 8 through the first air duct 16 for heating, and then opens the second damper 12 to return the air to the finned heat exchange tube 6;

[0049] When solar energy is insufficient on cloudy and snowy days, the air in the fin heat exchange tube 6 is heated by the resistance heater 18 and then released into the greenhouse 9 to provide the heat required by the greenhouse 9.

[0050] Example 3

[0051] In the greenhouse heating system of the present embodiment 3, the finned heat exchange tube 6 is an aluminum finned heat exchange tube, and the filling medium 7 is paraffin. In specific applications, the scheme of the present invention is also applicable to other finned heat exchange tubes 6 and filling media 7.

[0052] The greenhouse heating system of this implementation example 3 includes a same-path phase-change heat storage and release device 10 and a solar thermal conversion and collection device, wherein the same-path phase-change heat storage and release device 10 includes a steel plate container, a steel plate seal 2, an air duct, a paraffin filling port 4, an aluminum plate bracket 5, a finned aluminum heat exchange tube and paraffin.

[0053] Specifically, paraffin is injected into the steel plate container through the paraffin filling port 4, and the fins of the finned aluminum heat exchange tube are used to exchange heat with the heat storage material. Paraffin is a heat storage phase change material, which is solid at room temperature and liquid at a temperature of 45-75°C, and can reduce the heat storage volume.

[0054] The steel plate container is made of a steel plate rolled into a cylinder, and steel plate plugs 2 are provided at both ends. The steel plate plugs 2 are used to fix the finned aluminum heat exchange tubes placed in the container, and the aluminum plate brackets 5 are used to support the aluminum tubes and separate the paraffin. The finned aluminum heat exchange tubes are used to pass air when storing heat and pass cold air when releasing heat, and perform inter-wall heat exchange with the paraffin.

[0055] The volume of the steel plate container is calculated using the formula V 容器 =M 石蜡 / ρ 石蜡 Sure.

[0056] The heat required by greenhouse 9 is calculated by the formula Q = V 温室 ρ 空气 C P ΔT is determined.

[0057] The mass of paraffin wax is calculated by the formula M 石蜡 = ФQ / (R 潜热 +C 石蜡 ΔT 石蜡液态 )Sure.

[0058] When the greenhouse heating system of this embodiment 3 is heating, the amount of paraffin wax is determined according to the heat required by the greenhouse 9. Specifically, the amount of paraffin wax (mass and volume) can be calculated by multiplying the heat required by the greenhouse 9 by a safety factor Φ (generally 1.5-2.0).

[0059] When the greenhouse heating system of Example 3 is used to store heat in the greenhouse 9 during the day, the controller timer button is turned on, and the circulating fan 11 sends the air heated by the collector 8 through the second air duct 19 to the finned aluminum heat exchange tubes in the same-path phase change heat storage and release device 10. After heat exchange, the air is returned to the collector 8 through the first air duct 16 for heating to complete the hot air circulation heat storage.

[0060] When the greenhouse heating system of this embodiment 3 is used to heat the greenhouse 9 at night, the circulating fan 11 sends the air from the collector 8 to the finned aluminum heat exchange tube through the second air duct 19. After heat exchange, the air is released into the greenhouse 9 through the third air duct 20 to carry out cold air circulation heating at night.

[0061] Specifically, the solar thermal conversion heat collection device includes a collector 8, a circulating fan 11, a three-way interface (i.e., a third air door 13), a first air door 14, a second air door 12, a first air duct 16, a second air duct 19, a third air duct 20, a heat release port 15, a resistance heater 18 and an electronic control device 17.

[0062] The heat collector 8 converts solar radiation energy into heat energy and heats the heat transfer medium, air. In this embodiment 3, the heat collector 8 is mainly assembled on the bracket in a series-parallel manner.

[0063] When storing heat, the circulating fan 11 conveys the hot air in the collector 8 through the second air duct 19 and the second air gate 12 to the finned aluminum heat exchange tubes of the same-path phase-change heat storage and release device 10 for heat storage; when releasing heat, the circulating fan 11 conveys the hot air in the finned aluminum heat exchange tubes of the same-path phase-change heat storage and release device 10 through the third air duct 20 and the third air gate 13 to the greenhouse 9 for heat release; when the air heat in the finned aluminum heat exchange tubes of the same-path phase-change heat storage and release device 10 is lower than the set value, the electronic control device 17 opens the first air gate 14, and the circulating fan 11 inputs the air in the finned aluminum heat exchange tubes into the collector 8 through the first air duct 16 for heating, and then opens the second air gate 12 to return the air to the finned aluminum heat exchange tubes.

[0064] When solar energy is insufficient on cloudy and snowy days, the air in the finned aluminum heat exchange tubes is heated by the resistance heater 18 and then released into the greenhouse 9 to provide the heat required by the greenhouse 9.

[0065] The electronic control device 17 is used to open or close the first damper 14, the second damper 12, the third damper 13 and / or the resistance heater 18 according to the heat storage and release needs, the set time period and the set temperature.

[0066] In the present embodiment 3, the heat in the same-path phase-change heat storage device 10 is mainly the heat converted from light and heat by the solar collector 8 .

[0067] The circulating heating and heat storage of air is that the circulating fan 11 sends the air heated by the collector 8 to the same-path phase-change heat storage and release device 10 through the connecting air duct for heat exchange, and then returns to the collector 8 for heating.

[0068] The heat release of the same-path phase-change heat storage and release device 10 - heating of the greenhouse 9 is carried out by the circulating fan 11 which sends the air in the greenhouse 9 through the air duct into the same-path phase-change heat storage and release device 10 for heat exchange. After the air is heated, it is added to the greenhouse 9 to provide heat for the greenhouse 9.

[0069] Heat storage and heat release are not performed at the same time. Heat release and heat storage are achieved by opening and closing the first damper 14, the second damper 12 and the third damper 13. When storing and releasing heat, the air uses the same pipe in the same phase change heat storage and release device 10. The pipe through which the air in the same phase change heat storage and release device 10 flows has fins, the purpose of which is to reduce the "sandwich" phenomenon during heat release.

[0070] The first damper 14, the second damper 12 and the third damper 13 are opened in a time-controlled manner to realize the alternating conversion of heat storage and heat release, which can improve the heat exchange efficiency.

[0071] The same-path phase-change heat storage and release device used in the greenhouse heating system of this embodiment 3 is a partition-type heat exchanger with metal fins on the outside of the heat exchange tubes. The tubes and their fins divide the heat storage material in the heat collection pool, and the stored heat is easily released, so that the effective heat release rate of phase-change heat storage is significantly improved; at the same time, the same air duct is used to complete heat storage and release, and an electronic control device is used to implement hot air circulation heat storage during the day and cold air heating circulation heating mode at night, which simplifies the automatic control process; and by using heat storage materials (paraffin) for heat storage, it is possible to increase the heat storage capacity while reducing the heat storage space.

[0072] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A greenhouse heating system, characterized in that: The invention comprises a phase-change heat storage and release device on the same path, a first air duct, a second air duct, a third air duct, a three-way interface, a heat collector and an electronic control device, wherein the first interface of the three-way interface is connected to the air outlet of the phase-change heat storage and release device on the same path, the second interface of the three-way interface is connected to the first air duct, the first air duct is connected to the air inlet of the heat collector, a first air door is arranged on the first air duct, the air outlet of the heat collector is connected to the air inlet of the phase-change heat storage and release device on the same path through the second air duct, a circulating fan and a second air door are arranged on the second air duct, the third interface of the three-way interface is connected to the third air duct, the third air duct is connected to the heat release port, the third air duct is arranged with a third air door, a resistance heater is arranged on the air outlet of the phase-change heat storage and release device on the same path, and the electronic control device is electrically connected to the circulating fan, the first air door, the second air door, the third air door and the resistance heater respectively, and is used to control the opening and closing of the circulating fan, the first air door, the second air door, the third air door and the resistance heater.

2. The greenhouse heating system according to claim 1, characterized in that: The same-path phase-change heat storage and release device comprises a container body, fin heat exchange tubes and a filling medium. A filling port is arranged on the top of the container body, a plurality of fin heat exchange tubes are distributed in the container body, and the filling medium is injected into the container body through the filling port.

3. The greenhouse heating system according to claim 2, characterized in that: The filling medium is paraffin.

4. The greenhouse heating system according to claim 2, characterized in that: The container body is a cylinder rolled from a steel plate, and steel plate plugs are respectively provided at both ends of the cylinder, and the steel plate plugs are used to fix the fin heat exchange tube placed in the container body.

5. The greenhouse heating system according to claim 1, characterized in that: It also includes a solar energy and resistance heating device, which provides working heat energy for the greenhouse heating system.

6. The greenhouse heating system according to claim 1, characterized in that: The number of the heat release ports is multiple.

7. The greenhouse heating system according to any one of claims 1 to 6, characterized in that: The collector is a solar collector.

8. A heating control method for a greenhouse heating system, characterized in that: Using the greenhouse heating system according to any one of claims 1 to 7, the method comprises: When storing heat, the circulating fan transports the hot air in the collector through the second air duct and the second air door to the finned heat exchange tubes of the phase change heat storage and release device on the same path for heat storage; When releasing heat, the circulating fan transports the hot air in the finned heat exchange tube of the phase change heat storage and release device in the same path through the third air duct and the third air door to the greenhouse for heat release; When the air heat in the finned heat exchange tube of the same-path phase-change heat storage device is lower than the set value, the electronic control device opens the first damper, and the circulating fan inputs the air in the finned heat exchange tube into the collector through the first air duct for heating, and then opens the second damper to return the air to the finned heat exchange tube; When solar energy is insufficient on cloudy and snowy days, the air in the finned heat exchange tubes is heated by a resistance heater and then released into the greenhouse to provide the heat needed by the greenhouse.

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