Agricultural cooling structure

Abstract

To provide an agricultural cooling structure excellent in weather resistance and capable of easily lowering the temperature of agricultural products to a temperature lower than the outside air temperature in a structure for cooling the agricultural products in a facility surrounded by a heat insulating material by radiation cooling.SOLUTION: The cooling structure 1 for agriculture includes an outer covering 3 which constitutes at least a part of an exterior for surrounding and thermally insulating a farm crop 9 to be cultivated and transmits infrared rays, and an inner covering 5 which is provided in a space S surrounded by the outer covering 3 so as to face the outer covering 3 with a space therebetween, absorbs infrared rays of a specific wavelength band including a wavelength of infrared rays radiated from the farm crop 9, and radiates the infrared rays to the outside of the space S through the outer covering 3 and reflects light other than the infrared rays of the specific wavelength band.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an agricultural cooling structure. [Background technology]

[0002] In order to cultivate agricultural crops within a temperature range appropriate for their growth, some facilities, such as greenhouses, surround agricultural crops with thermal insulation. However, such facilities require a means to ensure that the temperature within the space surrounded by the thermal insulation does not exceed the temperature range appropriate for crop growth. While such means include opening part of the thermal insulation or using a ventilation fan to introduce outside air into the space to lower the temperature, this method has the problem of not being able to lower the temperature within the space below the outside air temperature. Another method involves using air conditioning equipment such as an air conditioner to lower the temperature within the space, but this method requires significant energy costs. Another method involves using multiple layers of thermal insulation to make it difficult for the temperature within the space to rise, but this method has the problem of not being able to lower the temperature within the space unless used in conjunction with an air conditioning equipment. Meanwhile, methods for lowering temperature using radiative cooling are also known. For example, Patent Document 1 discloses a structure in which a radiative cooling element consisting of a laminated infrared emitting layer and a light reflective layer is attached to the roof of an agricultural greenhouse. In this structure, the infrared radiation layer radiates heat as infrared rays to cool the inside of the agricultural greenhouse, while the light-reflecting layer reflects sunlight, preventing the temperature inside the agricultural greenhouse from rising due to sunlight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-182428 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the structure of Patent Document 1, when the outside temperature rises or wind blows on the infrared radiation layer, the infrared radiation layer rises in temperature due to convective heat transfer with the outside air. As a result, the temperature drop due to radiative cooling is offset by the temperature rise due to convective heat transfer with the outside air, making it difficult to lower the temperature of the crops in the agricultural greenhouse below the outside temperature. Furthermore, in the structure of Patent Document 1, the infrared radiation layer is exposed to the outside air, making it susceptible to deterioration due to wind and rain, and there were problems with weather resistance.

[0005] The present invention has been made to solve these problems, and its purpose is to provide an agricultural cooling structure that uses radiative cooling to cool agricultural crops in a facility surrounded by insulation, which can easily lower the temperature of the crops to a temperature lower than the outside air temperature and has excellent weather resistance. [Means for solving the problem]

[0006] The agricultural cooling structure of the present invention comprises an outer lining that forms at least a part of an exterior that surrounds and insulates cultivated agricultural crops and is transparent to infrared rays, and an inner lining that is arranged in the space surrounded by the exterior, facing the outer lining at a distance from the outer lining, absorbing infrared rays in a specific wavelength band that includes the wavelength of infrared rays emitted by the agricultural crops and radiating the infrared rays outside the space through the outer lining, and reflecting light other than infrared rays in the specific wavelength band. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an agricultural cooling structure that uses radiative cooling to cool agricultural crops in a facility surrounded by insulation, which can easily lower the temperature of the crops to a temperature lower than the outside air temperature and has excellent weather resistance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a vertical cross-sectional view showing an agricultural cooling structure according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view showing a first modified example of the agricultural cooling structure according to the first embodiment of the present invention. [Figure 3] FIG. 4 is a vertical cross-sectional view showing a second modified example of the agricultural cooling structure according to the first embodiment of the present invention. [Figure 4] FIG. 10 is a vertical cross-sectional view showing a third modified example of the agricultural cooling structure according to the first embodiment of the present invention. [Figure 5] FIG. 4 is a vertical cross-sectional view showing an agricultural cooling structure according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a vertical cross-sectional view showing an agricultural cooling structure according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments shown below, some components are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are applied as appropriate to the details of the omitted technologies within the scope of the content described below.

[0010] First, the configuration of the agricultural cooling structure according to the first embodiment will be described with reference to Figs. 1 to 4. Fig. 1 is a vertical cross-sectional view showing the agricultural cooling structure according to the first embodiment of the present invention. Fig. 2 is a vertical cross-sectional view showing a first modified example of the agricultural cooling structure according to the first embodiment of the present invention. Fig. 3 is a vertical cross-sectional view showing a second modified example of the agricultural cooling structure according to the first embodiment of the present invention. Fig. 4 is a vertical cross-sectional view showing a third modified example of the agricultural cooling structure according to the first embodiment of the present invention.

[0011] The agricultural cooling structure 1 shown in Figure 1 is a structure that uses radiative cooling to cool agricultural crops. Radiative cooling is a phenomenon in which an object lowers its temperature by emitting electromagnetic waves. The agricultural cooling structure 1 is a structure that lowers the temperature of agricultural crops 9 by emitting infrared rays, which are electromagnetic waves emitted by agricultural crops 9, into the atmosphere. In this case, the agricultural cooling structure 1 is a greenhouse installed on the ground 7, such as a field, and is equipped with an outer cladding 3 (exterior) and an inner cladding 5.

[0012] The outer covering 3 is a component that constitutes at least a part of the exterior that surrounds and insulates the cultivated crops 9, and in Figure 1 it constitutes the entire exterior. The outer covering 3 is a transparent sheet-like material that covers a dome-shaped framework (not shown). The outer covering 3 is made of an insulating material that is transparent to infrared rays. This is because if the outer covering 3 were made of a material that absorbs infrared rays, the infrared rays emitted by the crops 9 and other crops would be absorbed by the outer covering 3 and would not be released into the atmosphere, making it difficult to lower the temperature of the crops 9. Polyethylene is a specific example of an insulating material that is transparent to infrared rays.

[0013] The lining 5 is a member that absorbs infrared rays emitted by the crops 9 in the space S surrounded by the exterior lining 3 and radiates them to the outside of the space S via the lining 3, and is installed in the space S so as to face the lining 3. In FIG. 1, the lining 5 is shown as a dome-shaped sheet supported by a framework (not shown) that supports the lining 3.

[0014] In this configuration, the lining 5 absorbs the infrared rays emitted by the crops 9 as shown by arrow A1 and radiates them outside the space S as shown by arrow A2, thereby lowering the temperature of the crops 9 in the space S through radiative cooling.

[0015] The inner lining 5 is provided at a distance from the outer lining 3. This creates an insulating layer between the inner lining 5 and the outer lining 3, which inhibits heat transfer from the outer lining 3 to the inner lining 5. Therefore, even if the outer lining 3 heats up due to convective heat transfer with the outside air, the temperature rise of the inner lining 5 can be inhibited, making it easy to lower the temperature of the crops 9 to a temperature lower than the outside air temperature. Furthermore, by placing the inner lining 5 inside the outer lining 3, wind and rain do not directly hit the inner lining 5, making it less likely for the inner lining 5 to deteriorate due to wind and rain. Therefore, even if the agricultural cooling structure 1 is a structure that uses radiative cooling to cool a facility that surrounds the crops 9 with insulation, it is easy to lower the temperature of the crops 9 to a temperature lower than the outside air temperature and has excellent weather resistance.

[0016] The lining 5 absorbs infrared rays in a specific wavelength band and radiates them outside the space S through the outer lining 3. The specific wavelength band here refers to a wavelength band that includes the wavelength of infrared rays emitted by the crops 9. For example, when the temperature of the crops 9 is approximately 30°C, the wavelength of the infrared rays emitted by the crops 9 is approximately 7.5 μm to 13.5 μm, so the specific wavelength band is in the range of 7.5 μm to 13.5 μm. The wavelength band of 7.5 μm to 13.5 μm overlaps with a wavelength band known as the "atmospheric window." The "atmospheric window" is a wavelength band of infrared rays that are difficult to absorb by the atmosphere. The infrared rays radiated by the lining 5 outside the space S are released through the atmosphere into outer space, where the temperature is approximately -270°C. In this case, if the wavelength band of the emitted infrared rays falls within the "atmospheric window," the infrared rays are difficult to absorb by the atmosphere, so most of the infrared rays emitted by the lining 5 can be released into outer space, improving the efficiency of radiative cooling. Furthermore, "absorbs infrared rays" means that the infrared absorption rate is 50% or more (the infrared emissivity is also 50% or more).

[0017] On the other hand, lining 5 reflects light other than infrared light in a specific wavelength band, as indicated by arrow B. This prevents sunlight with wavelengths other than the specific wavelength band from entering space S. This prevents the temperature of crops 9 from rising due to the thermal energy of sunlight. Note that "reflecting light" means that the light reflectance is 50% or higher. Materials that absorb and radiate infrared light in a specific wavelength band, like lining 5, are known as radiative cooling materials, and one example is "SPACECOOL (registered trademark)" manufactured by SPACECOOL Co., Ltd. (Osaka Gas Co., Ltd.).

[0018] As shown in FIG. 2 , the agricultural cooling structure 1 may include a fan 11 that generates forced convection in the air within the space S. The fan 11 is installed within the space S and is a fan that draws in air from below and exhausts it from above, as indicated by arrow C, thereby generating a bottom-to-up airflow within the space S. By generating this bottom-to-up airflow within the space S, the air above within the space S is pushed downward by the airflow. Air below is also drawn in by the fan 11 and exhausted upward. Therefore, by providing the fan 11, the air within the space S can be circulated vertically. Furthermore, by tilting the intake and exhaust directions relative to the vertical, the air within the space S can be circulated horizontally. By circulating the air within the space S in this manner, temperature imbalances within the space S are suppressed. Therefore, the agricultural cooling structure 1 can reduce the temperature difference between the crops 9 when multiple crops 9 are grown within the space S. In FIG. 2, the fan 11 is provided inside the space S, but the fan 11 may be provided outside the space S and connected to the space S by an intake flow path and an exhaust flow path (not shown).

[0019] As shown in FIG. 3, the agricultural cooling structure 1 may include a heat insulating membrane material 31. The heat insulating membrane material 31 is provided inside the lining 5 in the space S. The heat insulating membrane material 31 faces the lining 5. In this configuration, the transfer of heat between the inside and outside of the space S is suppressed by the exterior (exterior lining 3) and the heat insulating membrane material 31. This improves the heat insulating effect compared to when insulation is achieved only by the exterior. While the heat insulating membrane material 31 is required to have thermal insulation properties, it is preferable that it is made of a material that transmits infrared rays, because this allows infrared rays radiated from the crops 9 to reach the lining 5 without being absorbed by the heat insulating membrane material 31. A transparent material is also preferable, because it allows sunlight to reach the crops 9 while maintaining thermal insulation properties. Examples of such materials include the same materials as the lining 5.

[0020] The lining 5 reflects light other than infrared light in a specific wavelength band, so it is almost completely opaque to sunlight. However, if natural light is required for growing the crops 9, it is preferable to provide a sunlight intake. The sunlight intake may be provided by providing a partial opening in the lining 5, or the crops 9 may be partially surrounded by the lining 5, with the portion not surrounded by the lining 5 serving as the sunlight intake. On the other hand, as shown in FIG. 4 , a configuration in which at least a portion of the lining 5 is openable is preferable. Specifically, in FIG. 4 , vertically extending notches 13 are formed in the lining 5. Note that multiple notches 13 are arranged in a direction from the front to the back of the page in FIG. 4 . In this configuration, the portion of the lining 5 sandwiched between adjacent notches 13 is wound upward as a winding portion 13a and fixed in the wound state, thereby opening the portion where the wound lining 5 was located, and becoming a sunlight intake. In this configuration, sunlight from outside enters the space through the open portion of the lining 5. 4, sunlight can be taken in from the open portion of lining 5 in space S as indicated by arrow D, while infrared rays radiated from crops 9 as indicated by arrow A1 can be absorbed by lining 5 and radiated to the outside of space S as indicated by arrow A2. This allows sunlight to be taken in to space S while radiative cooling of crops 9. This concludes the description of the configuration of the agricultural cooling structure 1 according to the first embodiment.

[0021] As described above, according to the first embodiment, the agricultural cooling structure 1 includes the outer lining 3 and the inner lining 5. In this configuration, the inner lining 5 absorbs infrared rays emitted by the crops 9 and radiates them outside the space S, thereby lowering the temperature of the crops 9 in the space S through radiative cooling. Therefore, the crops 9 can be cooled even when a facility is used in which the crops 9 are surrounded by thermal insulation. Furthermore, in this configuration, the inner lining 5 is provided at a distance from the outer lining 3. This allows air to be interposed between the inner lining 5 and the outer lining 3, forming an insulating layer. Therefore, even if the temperature of the outer lining 3 rises due to convective heat transfer with the outside air, the temperature rise of the inner lining 5 can be suppressed, making it easier to lower the temperature of the crops 9 to a temperature lower than the outside air temperature. Furthermore, by placing the inner lining 5 inside the outer lining 3, wind and rain do not directly hit the inner lining 5, making it less likely to deteriorate due to wind and rain. Therefore, even though agricultural cooling structure 1 is a structure that uses radiation cooling to cool a facility that surrounds crops 9 with insulation, it can easily lower the temperature of crops 9 to a temperature lower than the outside air temperature and has excellent weather resistance.

[0022] Furthermore, according to the first embodiment, the agricultural cooling structure 1 may include a fan 11 that generates forced convection in the air within the space S. In this configuration, the fan 11 circulates the air within the space S, thereby suppressing temperature imbalance within the space S. Therefore, when multiple crops 9 are grown within the space S, the agricultural cooling structure 1 can reduce the temperature difference between the crops 9.

[0023] Furthermore, according to the first embodiment, the agricultural cooling structure 1 may include a heat insulating membrane material 31 that is provided inside the lining 5 in the space S and faces the lining 5. In this configuration, the transfer of heat between the inside and outside of the space S is suppressed by the exterior (exterior lining 3) and the heat insulating membrane material 31. Therefore, the heat insulating effect can be improved compared to when insulation is provided by the exterior only.

[0024] Meanwhile, in the agricultural cooling structure 1 according to the first embodiment, at least a portion of the lining 5 may be openable / closable. In this configuration, sunlight is introduced into the space S through the open portion of the lining 5, while infrared rays radiated from the crops 9 are absorbed by the lining 5 and radiated to the outside of the space S. Thus, the crops 9 can be radiatively cooled while sunlight is introduced into the space S.

[0025] Next, a second embodiment will be described with reference to Fig. 5. In the second embodiment, a window glass provided on the outer wall of a closed agricultural greenhouse as the exterior is used as the outer cladding 3, and an inner cladding 5 is provided inside the closed agricultural greenhouse so as to face the window glass. In the second embodiment, elements that perform the same functions as in the first embodiment are given the same numbers, and the following description will mainly focus on the parts that differ from the first embodiment. Fig. 5 is a vertical cross-sectional view showing an agricultural cooling structure according to a second embodiment of the present invention.

[0026] As shown in FIG. 5 , an agricultural cooling structure 1a according to the second embodiment is installed in a closed agricultural greenhouse 21. The closed agricultural greenhouse 21 is an agricultural facility for cultivating crops 9 indoors, and includes an exterior wall 23 as an exterior, and a light-receiving window glass 25 (exterior) that forms part of the exterior. The agricultural cooling structure 1a uses the window glass 25 as an exterior cladding 3, and an interior cladding 5 is installed in a space S enclosed by the exterior wall 23, facing and spaced apart from the window glass 25. The agricultural cooling structure 1a also includes a rail 27. The rail 27 is a rod-shaped member disposed on the inner surface of the exterior wall 23 along the upper edge of the window glass 25, and has a structure similar to that of a curtain rail, for example. The interior cladding 5 is suspended from the rail 27 via a member, such as a runner (not shown), that can slide along the lower end of the rail 27. The interior cladding 5 can be folded like a curtain by moving the runner along the rail 27.

[0027] In this configuration, infrared rays emitted from the crops 9 as shown by arrow A1 are absorbed by the lining 5 and are then radiated to the outside of the space S through the window glass 25 as shown by arrow A2. Furthermore, if it is desired to let sunlight into the space S through the window glass 25, the lining 5 can be folded up. In this way, the window glass 25 that constitutes part of the exterior may be used as the outer lining 3. In this configuration, there is no need to prepare a separate outer lining 3. Furthermore, the agricultural cooling structure 1a can be retrofitted to an existing closed-type agricultural greenhouse 21.

[0028] Next, a third embodiment will be described with reference to Fig. 6. In the third embodiment, the agricultural cooling structure 1 according to the first embodiment is provided so as to cover crops 9 in a closed agricultural greenhouse 21. In the third embodiment, elements that perform the same functions as those in the first embodiment are given the same numbers, and differences from the first embodiment will be mainly described. Fig. 6 is a vertical cross-sectional view showing the agricultural cooling structure according to the third embodiment of the present invention.

[0029] The agricultural cooling structure 1 according to the third embodiment is provided so as to surround the crops 9 in a closed agricultural greenhouse 21. The structure of the agricultural cooling structure 1 is the same as that of the first embodiment, and the structure of the closed agricultural greenhouse 21 is the same as that of the second embodiment. When multiple crops 9 are grown in the closed agricultural greenhouse 21, the agricultural cooling structure 1 may surround all of the multiple crops 9, or may surround only some of the crops 9. In this way, the agricultural cooling structure 1 may be provided so as to surround the crops 9 in the closed agricultural greenhouse 21. With this configuration, the inside of the closed agricultural greenhouse 21 can be locally cooled.

[0030] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the present invention, and other techniques may be appropriately combined to the extent possible. Furthermore, publicly known or well-known techniques may be combined to the extent possible.

[0031] For example, in the above embodiment, a vinyl greenhouse is exemplified as the agricultural cooling structure 1, but a structure similar to mulching using plastic may also be used. [Explanation of symbols]

[0032] 1, 1a: Agricultural cooling structure 3: Exterior 5: Lining 9: Crops 11: Fan 25: Window glass (exterior) 31: Heat insulating membrane material S: Space

Claims

1. an infrared-transparent outer covering that forms at least a portion of an exterior that insulates and surrounds the cultivated crops; an inner lining that is provided in the space surrounded by the exterior so as to face the outer lining at a distance from the outer lining, absorbing infrared rays in a specific wavelength band that includes the wavelength of infrared rays emitted by the crops and radiating the infrared rays to the outside of the space through the outer lining, and reflecting light other than infrared rays in the specific wavelength band. Agricultural cooling structure characterized by:

2. A fan is provided to generate forced convection in the air within the space. The agricultural cooling structure according to claim 1 .

3. A heat insulating membrane material is provided inside the lining in the space and faces the lining. The agricultural cooling structure according to claim 1 or 2, characterized in that

4. At least a portion of the lining is retractable. The agricultural cooling structure according to claim 1 or 2, characterized in that

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