Solar heat storage type vertically-layered greenhouse wall

Abstract

The invention relates to the technical field of agricultural facilities, and discloses a solar heat storage type vertically-layered greenhouse wall which comprises a heat preservation layer and a heat storage layer, the south side of the heat preservation layer is covered with the heat storage layer, and the heat storage layer comprises a lower heat storage layer and an upper heat storage layer which are sequentially arranged from bottom to top; the phase change layer covers the south side of the heat storage layer, and the phase change layer comprises a lower phase change layer and an upper phase change layer which are sequentially arranged from bottom to top; the solar heat collection system comprises a circulating heat exchange pipe, one part of the circulating heat exchange pipe is embedded into the phase change layer to form a heat exchange section, and the other part of the circulating heat exchange pipe is connected with the heat preservation water tank and the heat exchange section; the gravity heat pipes are vertically embedded into the phase change layer and the heat storage layer and sequentially penetrate through the lower phase change layer, the lower heat storage layer, the upper heat storage layer and the upper phase change layer; and the convection heat exchange air duct system comprises an air duct, and the air duct penetrates through the phase change layer and the heat storage layer and is arranged in the heat storage layer in the height direction of the wall body.

Description

Technical Field

[0001] This invention relates to the field of agricultural facilities technology, and particularly to the field of agricultural greenhouse construction, specifically a solar-powered, heat-storing, vertically layered greenhouse wall. Background Technology

[0002] As an important agricultural facility, the heat storage and insulation performance of the walls of a solar greenhouse directly affects the indoor thermal and humidity environment and crop growth. Currently, the walls of solar greenhouses generally adopt a traditional homogeneous structure in the vertical direction. Although such walls have a certain heat storage and release capacity, they do not fully consider the differences in heat and humidity distribution along the vertical direction. Experimental studies show that the north wall of the greenhouse has a significant temperature and humidity gradient in the vertical direction: under sunny conditions, the temperature and volumetric moisture content of the inner surface of the wall decrease with increasing height; in terms of heat flux density, the wall is in an endothermic state from 9:00 to 15:00 during the day, with the lower part absorbing more heat than the upper part, while the wall is in an exothermic state during the rest of the day, with the lower part releasing more heat than the upper part. Under cloudy conditions, although temperature fluctuations are slower and the heat absorption period is shorter, the above vertical distribution pattern is still consistent with that on sunny days.

[0003] Because traditional homogeneous walls are not optimized for the aforementioned vertical thermal and moisture gradients, they suffer from the following drawbacks: 1. The structure is mismatched with the heat and humidity distribution, and cannot adapt to differences in vertical gradients: The existing walls use homogeneous materials and uniform structures in the vertical direction, without taking into account the vertical thermal and moisture gradient changes that exist in actual measurements. They cannot respond to differences in temperature, moisture content and heat flux density at different heights, and cannot achieve matching thermal and moisture regulation capabilities in the vertical direction, resulting in limited regulation.

[0004] 2. Insufficient heat storage capacity: Because the heat flux density in the lower part of the wall is high, but the homogeneous structure is not designed to enhance heat storage, the overall heat storage capacity of the wall is weak. It is difficult to fully absorb and store the heat transferred from the soil to the upper part and the heat from solar radiation, resulting in insufficient heat storage during the daytime heat absorption phase and affecting the heat release guarantee at night.

[0005] 3. Low efficiency in heat and humidity regulation negatively impacts crop growth environment: At night or when there is insufficient sunlight, the walls cannot release heat as needed, resulting in large fluctuations in indoor temperature and uneven humidity distribution, which is detrimental to crop growth and development. At the same time, due to inaccurate heat and humidity regulation, some areas become overheated or overhumidified, resulting in energy waste.

[0006] 4. Lack of tiered control mechanisms leads to low overall energy efficiency: Homogeneous walls cannot implement differentiated responses to the heat and moisture transfer characteristics of different sections, resulting in low overall efficiency of greenhouse environment regulation, which is not conducive to energy conservation and production stability.

[0007] Therefore, it is necessary to develop a solar-powered, heat-storing, vertically layered greenhouse wall to improve the control of the internal thermal and humidity environment of the greenhouse. Summary of the Invention

[0008] To address the problems of current solar greenhouse walls, which generally adopt a vertical homogeneous structure, resulting in inability to adapt to the actual differences in heat and humidity distribution along the vertical direction, insufficient heat storage capacity, low heat and humidity control efficiency, and lack of stratified control methods, leading to overall low energy efficiency, large temperature and humidity fluctuations, energy waste, and poor crop growth environment, this invention provides a solar thermal storage vertical stratified greenhouse wall.

[0009] This invention is achieved using the following technical solution: it includes a thermal insulation layer. A heat storage layer covers the south side of the insulation layer, and the heat storage layer includes a lower heat storage layer and an upper heat storage layer arranged sequentially from bottom to top; A phase change layer covers the south side of the heat storage layer, and the phase change layer includes a lower phase change layer and an upper phase change layer arranged sequentially from bottom to top; A solar thermal collector system includes a circulating heat exchange tube, a portion of which is embedded in a phase change layer to form a heat exchange section, and the other portion is connected to an insulated water tank and the heat exchange section. Several sets of gravity heat pipes are vertically embedded in the phase change layer and the heat storage layer, and sequentially penetrate the lower phase change layer, the lower heat storage layer, the upper heat storage layer and the upper phase change layer. A convection heat exchange duct system includes a duct that runs through a phase change layer and a heat storage layer, and is arranged along the height of the wall in the heat storage layer.

[0010] During implementation, it includes an insulation layer made of polystyrene insulation board with a thermal conductivity of 0.03–0.035 W·m. -1 •℃ -1 .

[0011] A heat storage layer, covering the south side of the insulation layer, comprises a lower heat storage layer and an upper heat storage layer arranged sequentially from bottom to top; the lower heat storage layer is made of a high-density load-bearing material with a thermal conductivity of 0.85–0.9 W·m. -1 •℃ -1 Its density is 1850–1900 kg / m³ 3 ; The upper heat storage layer is made of a lightweight material with a thermal conductivity of 0.5–0.6 W·m. -1 •℃ -1 Its density is 1500–1600 kg / m³ 3 .

[0012] A phase change layer covers the south side of the heat storage layer. The phase change layer includes a lower phase change layer and an upper phase change layer arranged sequentially from bottom to top. The lower phase change layer is made of paraffin phase change material with a latent heat of 200-220 kJ / kg, and the upper phase change layer is made of paraffin phase change material with a latent heat of 180-200 kJ / kg.

[0013] Furthermore, the lower heat storage layer and the lower phase change layer are at the same height to form a lower functional area, with a height range Z of 0 to 1.4 m, which enhances the heat storage capacity and meets the high heat absorption and release requirements of the lower part; and the upper heat storage layer and the upper phase change layer are at the same height to form an upper functional area, with a height range Z of 1.4 to 2.7 m; the lightweight material reduces the self-weight of the wall and meets the low heat absorption and release requirements of the upper part.

[0014] A solar thermal collector system includes a circulating heat exchange tube made of PVC pipe. The circulating heat exchange tube is arranged in a serpentine manner within a phase change layer. A portion of the circulating heat exchange tube is embedded in the phase change layer to form a heat exchange section, and the other portion is connected to an insulated water tank and the heat exchange section. Solar thermal collection systems also include: Insulated water tank; A solar collector, used to absorb heat, is connected to an insulated water tank and is installed at an angle on the roof of a solar greenhouse; A circulating pump is used to drive the heat transfer fluid to circulate in a closed loop consisting of a solar collector, an insulated water tank, and circulating heat exchange tubes.

[0015] Several sets of gravity heat pipes, each a ring-shaped copper heat pipe using methanol as the working medium, are vertically arranged and embedded perpendicularly into the phase change layer and the heat storage layer. They sequentially penetrate the lower phase change layer, the lower heat storage layer, the upper heat storage layer, and the upper phase change layer, with a spacing of 500 mm between adjacent gravity heat pipes. During the daytime when the temperature is high, the portion of the gravity heat pipe located within the phase change layer serves as its evaporation section, while the portion located within the heat storage layer serves as its condensation section; the opposite occurs at night.

[0016] A convection heat exchange duct system includes a duct that runs through a phase change layer and a heat storage layer, and is arranged along the height of the wall in the heat storage layer. The distance between two adjacent ducts is 500mm. The lower end of the duct is provided with an air inlet, the upper end with an air outlet, and a dustproof net is provided at the air outlet. A temperature-sensing damper is provided at the air inlet.

[0017] This invention also provides an application of a solar thermal storage vertical layered greenhouse wall on the north wall of a greenhouse.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a solar-powered, thermally stored, vertically layered greenhouse wall. 1. Utilizing the vertical thermal and humidity characteristics of the wall: Through the layered design of the upper and lower parts, the vertical temperature, moisture content and heat flux density distribution characteristics of the wall in the test are matched, so that each height area of ​​the wall can perform optimally and improve the overall thermal and humidity control efficiency.

[0019] 2. Significantly improves heat storage and release efficiency: Integrates solar thermal collection, phase change heat storage and gravity heat pipe technology to improve the heat storage and release efficiency of the wall.

[0020] 3. High efficiency in utilizing clean energy: Solar thermal systems can meet 60% to 70% of the heat storage needs of the walls, reducing the consumption of traditional energy, lowering greenhouse operating costs, and reducing carbon emissions, which is in line with the trend of green agriculture development.

[0021] 4. Reliable structure and easy maintenance: The layered structure has a mature construction process and a low failure rate for core components such as gravity heat pipes and air ducts. In the later stage, only the heat pipe sealing and air duct cleanliness need to be checked periodically, resulting in low maintenance costs. Attached Figure Description

[0022] Figure 1 This is a side sectional view of the present invention.

[0023] Figure 2 This is a schematic diagram of the overall structure of the present invention.

[0024] Figure 3 This is a schematic diagram of the installation of the gravity heat pipe in this invention.

[0025] Figure 4 This is a schematic diagram of the installation of the circulating heat exchange tubes and air ducts in this invention.

[0026] In the diagram: 1. Insulation layer; 2. Upper heat storage layer; 3. Upper phase change layer; 4. Insulated water tank; 5. Solar collector; 6. Lower phase change layer; 7. Circulating heat exchange tube; 8. Gravity heat pipe; 9. Lower heat storage layer; 10. Air duct. Detailed Implementation

[0027] Specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] A solar-powered, thermally stored, vertically layered greenhouse wall, as described in this embodiment, is suitable for the north wall of a greenhouse. Figures 1-4 As shown, it includes insulation layer 1, which is made of polystyrene insulation board with a thermal conductivity of 0.03–0.035 W•m. -1 •℃ -1 .

[0029] A heat storage layer, covering the south side of the insulation layer 1, comprises a lower heat storage layer 9 and an upper heat storage layer 2 arranged sequentially from bottom to top; the lower heat storage layer 9 is made of a high-density load-bearing material with a thermal conductivity of 0.85–0.9 W·m. -1 •℃ -1 Its density is 1850–1900 kg / m³ 3 In this embodiment, high-density load-bearing clay blocks are used. The upper heat storage layer 2 is made of a lightweight material with a thermal conductivity of 0.5–0.6 W·m. -1 •℃ -1 Its density is 1500–1600 kg / m³ 3 In this embodiment, lightweight expanded clay aggregate concrete blocks are used. A phase change layer covers the south side of the heat storage layer. The phase change layer includes a lower phase change layer 6 and an upper phase change layer 3 arranged sequentially from bottom to top. The lower phase change layer 6 is made of paraffin phase change material with a latent heat of 200-220 kJ / kg, and the upper phase change layer 3 is made of paraffin phase change material with a latent heat of 180-200 kJ / kg.

[0030] Furthermore, the lower heat storage layer 9 and the lower phase change layer 6 are at the same height to form a lower functional area with a height range Z of 0 to 1.4 m, which enhances the heat storage capacity and meets the high heat absorption and release requirements of the lower part; and the upper heat storage layer 2 and the upper phase change layer 3 are at the same height to form an upper functional area with a height range Z of 1.4 to 2.7 m; the lightweight material reduces the self-weight of the wall and meets the low heat absorption and release requirements of the upper part. Compared with the traditional homogeneous structure wall, this wall can achieve a stronger heat storage and release capacity.

[0031] The solar thermal collector system includes a circulating heat exchange tube 7, which is made of PVC pipe with a diameter of 20mm and a spacing of 300mm. The circulating heat exchange tube 7 is arranged in a serpentine pattern within the phase change layer. A portion of the circulating heat exchange tube 7 is embedded in the phase change layer to form a heat exchange section, and the other portion is connected to the insulated water tank 4 and the heat exchange section. Solar thermal collection systems also include: The insulated water tank 4 is wrapped with a 50mm thick rock wool insulation layer on the outside; Solar collector 5, used to absorb heat, is connected to insulated water tank 4 and is installed at an angle on the roof of the solar greenhouse; A circulating pump is used to drive the heat transfer fluid to circulate in a closed loop consisting of the solar collector 5, the insulated water tank 4, and the circulating heat exchange tube 7.

[0032] Several sets of gravity heat pipes 8, each a ring-shaped copper heat pipe using methanol as the working medium, are vertically arranged and embedded vertically into the phase change layer and the heat storage layer. They sequentially penetrate the lower phase change layer 6, the lower heat storage layer 9, the upper heat storage layer 2, and the upper phase change layer 3. The distance between adjacent gravity heat pipes 8 is 500 mm. During the daytime when the temperature is high, the portion of the gravity heat pipe 8 located within the phase change layer serves as its evaporation section, while the portion located within the heat storage layer serves as its condensation section; the opposite occurs at night.

[0033] The convection heat exchange duct system 10 includes a duct 10 that runs through the phase change layer and the heat storage layer and is arranged along the height of the wall in the heat storage layer. The distance between two adjacent ducts 10 is 500mm. The lower end of the duct 10 is provided with an air inlet and the upper end is provided with an air outlet. A dustproof net is provided at the air outlet. The air inlet is 100mm from the ground and the air outlet is 200mm from the top of the wall. A temperature-sensing damper is provided at the air inlet.

[0034] During daytime sunshine hours when using it: Sunlight illuminates the walls of the solar greenhouse, heating the phase change layer. Simultaneously, the solar collector 5 absorbs radiant heat, which in turn heats the circulating medium. In this embodiment, water is used as the circulating medium. A circulation pump drives the medium, heated to 30-50°C, through heat exchange pipes embedded in the phase change layer, exchanging heat with the phase change material. This increases the temperature of the phase change layer, causing it to melt and promoting heat storage; thus, solar energy is stored as latent heat.

[0035] As the phase change layer temperature rises, the methanol working medium within the evaporation section of the gravity heat pipe 8, which runs through it, evaporates. The methanol vapor rises to the condensation section, condenses and releases heat in the heat storage layer, rapidly transferring the heat to the storage layer for storage and condensing into liquid. Under gravity, it flows back to the evaporation section, forming a cycle that quickly transfers the heat from the phase change layer to the storage layer. Because the gravity heat pipe 8 runs through both the upper and lower sections, it facilitates the transfer of heat accumulated in the lower section to the upper section.

[0036] Nighttime indoor temperature drop period: As the water temperature drops in the evening, the circulation pump stops running, and the water in the heat exchange pipes dissipates heat naturally, helping the phase change layer maintain its temperature. When the temperature of the phase change material drops below the phase change point, it gradually solidifies and releases the stored latent heat into the room. At this time, the temperature of the phase change layer decreases, while the temperature of the heat storage layer is higher than that of the phase change layer. Methanol circulates in reverse in the gravity heat pipe 8, transferring the heat from the heat storage layer to the phase change layer, and then releasing it into the room through the phase change layer, thus achieving a delayed and slow release of heat.

[0037] When the indoor temperature drops below the set value (e.g., below 15℃), the temperature-sensing damper opens automatically. The heat released by the heat storage layer heats the air in the air duct 10, creating a thermal pressure difference. This drives the air to form a natural convection circulation from the bottom air inlet to the top air outlet. In other words, hot air flows into the room from the air outlet, and cold air enters the air duct 10 from the air inlet to replenish the indoor heat. The insulation layer 1 effectively inhibits the loss of heat stored in the wall to the outside, ensuring that heat is preferentially released into the room.

[0038] The scope of protection claimed by this invention is not limited to the specific embodiments described above. Moreover, for those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A solar-powered, thermally stored, vertically layered greenhouse wall, characterized in that: Including the insulation layer (1). A heat storage layer covers the south side of the insulation layer (1), and the heat storage layer includes a lower heat storage layer (9) and an upper heat storage layer (2) arranged sequentially from bottom to top. A phase change layer covers the south side of the heat storage layer. The phase change layer includes a lower phase change layer (6) and an upper phase change layer (3) arranged sequentially from bottom to top. A solar thermal collector system includes a circulating heat exchange tube (7), a portion of which is embedded in a phase change layer to form a heat exchange section, and the other portion is connected to an insulated water tank (4) and the heat exchange section; Several sets of gravity heat pipes (8) are vertically embedded in the phase change layer and the heat storage layer, and pass through the lower phase change layer (6), the lower heat storage layer (9), the upper heat storage layer (2) and the upper phase change layer (3) in sequence. A convection heat exchange duct (10) system, comprising a duct (10) that extends through the phase change layer and the heat storage layer and is arranged along the height of the wall in the heat storage layer.

2. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The lower phase change layer (6) is made of paraffin phase change material with a latent heat of 200-220 kJ / kg, and the upper phase change layer (3) is made of paraffin phase change material with a latent heat of 180-200 kJ / kg.

3. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The lower heat storage layer (9) is made of high-density load-bearing material with a thermal conductivity of 0.85–0.9 W·m. -1 •℃ -1 Its density is 1850–1900 kg / m³ 3 ; The upper heat storage layer (2) is made of a lightweight material with a thermal conductivity of 0.5–0.6 W·m. -1 •℃ -1 Its density is 1500–1600 kg / m³ 3 .

4. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The solar thermal collector system also includes: Insulated water tank (4); A solar collector (5) is used to absorb heat and is connected to an insulated water tank (4). It is installed at an angle on the roof of the solar greenhouse. A circulating pump is used to drive the heat transfer fluid to circulate in a closed loop consisting of the solar collector (5), the insulated water tank (4), and the circulating heat exchange tube (7).

5. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The circulating heat exchange tube (7) is arranged in a serpentine pattern within the phase change layer.

6. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The gravity heat pipe (8) is an annular copper heat pipe with methanol as the working medium, which is vertically arranged and the distance between two adjacent gravity heat pipes (8) is 500mm.

7. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The distance between two adjacent air ducts (10) is 500mm. The lower end of the air duct (10) is provided with an air inlet and the upper end is provided with an air outlet. A dustproof net is provided at the air outlet, and a temperature-sensing damper is provided at the air inlet.

8. The solar thermal storage vertical tiered greenhouse wall according to claim 1, characterized in that: The lower heat storage layer (9) has the same height as the lower phase change layer (6), and the upper heat storage layer (2) has the same height as the upper phase change layer (3).

9. Application of a solar thermal storage vertical layered greenhouse wall in the north wall of a greenhouse.

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