JP7489705B2 - Cooling systems and facilities equipped with cooling systems - Google Patents

Description

The present invention relates to technology for cooling the interior space of a facility.

2. Description of the Related Art There are facilities that have partition walls (note that the partition wall referred to in this application includes not only vertical or nearly vertical partition walls, but also nearly horizontal partition walls such as roofs) for separating an external environment from an indoor space.
For example, vinyl greenhouses, plant factories and other horticultural facilities fall under such categories.

Historically, horticultural facilities have been developed in an attempt to grow plants stably during cold seasons. Therefore, in many cases, the room temperature in the indoor space of a horticultural facility is kept higher than the temperature of the outside environment.
For these historical reasons, many technologies for maintaining high temperatures within facilities have been proposed and put into practical use since ancient times.

However, depending on the location of the horticultural facility, the temperature of the external environment may be higher than the temperature suitable for growing plants. In such cases, the temperature in the indoor space of the horticultural facility may be higher than the temperature suitable for growing plants. In such cases, it becomes necessary to lower the temperature of the air in the indoor space below the temperature of the air in the external environment.
In such cases, a cooling system is required.
Of course, cooling systems are not only needed in horticultural facilities. Even if the facility is a factory or warehouse, a cooling system is needed to lower the temperature inside the facility, for example, in the summer when the external temperature is high.

Of course, there are air conditioners that include heat exchangers, refrigerants, etc. for such purposes. However, as is well known, air conditioners such as those described above require a large amount of electricity to operate, and their use increases electricity bills.
As a technique to solve such problems, for example, in facilities with a relatively large indoor space such as horticultural facilities, a device called pad and fan is used, which is a device that installs a pad on the air intake port on the partition and an exhaust device on the exhaust port. The pad is a plate-shaped material made of a material with high breathability and moisture retention, and the air drawn into the indoor space through the air intake port by the exhaust device exhausting air from the indoor space to the outside environment through the exhaust port passes through the pad before being led into the indoor space. When the air passes through the pad, the temperature is reduced by, for example, several degrees Celsius due to evaporative cooling. This makes it possible to lower the room temperature of the indoor space below the temperature of the air in the outside environment.
Pad and fan equipment requires electricity to run the exhaust device; however, the amount of electricity required is less than that consumed by an air conditioner, making it cost-effective.

However, even with the pad and fan system, the pad needs to maintain a proper amount of water, so there is a cost to continuously spray the right amount of water onto the pad, and because the pad is exposed to the outside environment, a lot of water evaporates without contributing to cooling the air, so the amount of water required is large. Also, although the introduction cost is cheaper than that of an air conditioner, it is still relatively expensive.
For these reasons, it is difficult to say that pad-and-fan equipment has sufficiently reduced costs.

The objective of this invention is to reduce the cost of technology for lowering the temperature of the air inside a facility below the temperature of the air in the external environment.

In order to solve the above problems, the present inventors propose the following invention.
The invention is a cooling system for cooling an indoor space in a facility having a partition wall for isolating the indoor space from an outside environment.
The facility whose indoor space is cooled by the cooling system is, for example, but not limited to, a horticultural facility, a factory, a warehouse, etc. The facility has a partition wall for isolating the indoor space from the external environment. As already mentioned, the partition wall in this application includes not only a wall but also a roof, a ceiling, etc.
The cooling system includes an exhaust device arranged in the partition and having an exhaust port connecting the external environment and the indoor space, which exhausts air from the indoor space to the external environment; a hole provided in the ground at the edge of the facility so as to straddle the indoor space and the external environment when viewed in a plane, which connects the indoor space and the external environment; granular material arranged inside the hole; and a sprinkler device for sprinkling water on the granular material inside the hole.

This cooling system includes an exhaust device having an exhaust port. The exhaust device exhausts air in the indoor space of the facility to the outside environment. On the other hand, the cooling system includes a hole in the ground that spans between the outside environment and the indoor space of the facility. When the air in the indoor space is exhausted to the outside environment by the exhaust device, the air pressure in the indoor space becomes negative. As a result, air is supplied from the outside environment to the indoor space through the hole, in other words, via the underground.
In this way, the cooling system according to the present invention supplies air to the indoor space of the facility through the underground. The holes through which the air passes contain granular material, and the granular material is appropriately sprayed with water from a water sprinkler. As is well known, when the external environment is hot, for example, due to strong solar radiation, the temperature underground is lower than that on the ground surface. If the water sprinkler is arranged to spray water onto the granular material, the air is cooled by evaporative cooling when it passes between the granular material in the holes, in the same way as when it passes through the pad of a pad-and-fan system.
Therefore, by passing the air through the holes, which have a lower temperature than the ground surface, it is possible to cool the air supplied to the indoor space more efficiently than with the pad and fan system. Moreover, since the water supplied to the granular material exists in the holes, it is less likely to evaporate than when it is completely exposed to the outside environment, and in some cases it is possible to use the moisture in the ground as part of the water supplied to the granular material. Therefore, the amount of water required is smaller than with the pad and fan system, and a constant supply of water is not required, which makes it possible to reduce the cost of supplying water.

As described above, granular materials are arranged in the holes. The granular materials are not too fine, and need to be large enough to leave a space in the holes so that when the air in the indoor space is exhausted to the outside environment by the exhaust device, the air in the outside environment can be drawn into the indoor space through the holes. In other words, if the granular materials are too fine, the holes will be clogged with the granular materials, making it difficult to supply air to the indoor space through the holes, so the granular materials need to be selected in a range that does not cause such clogging. In this application, "granular" means "sufficiently smaller than the size of the holes". This definition also applies to the water-retaining material described later. This range is, for example, a diameter of the granular materials of about 10 to 20 cm. The shape and size of each granular material may or may not be the same.
In addition, the amount of water sprayed onto the granular material is limited to the extent that the holes function as flow paths for guiding air from the outside environment to the indoor space. For example, if the holes containing the granular material are filled with water, the holes will no longer function as flow paths for air as described above. Water is sprayed into the holes to the extent that this does not occur.
The granular material may be, for example, stone, such as crushed stone. If the granular material is stone, it may be possible to procure the granular material at the facility site, thereby reducing the cost of constructing the cooling system. It is preferable that the stone has a high water retention property, i.e., a high porosity. From this viewpoint, it is preferable that the type of stone constituting the granular material in the cooling system of the present invention is, for example, sedimentary rock rather than igneous rock.
In addition to the granular material, a granular water-retaining material having water retention properties may be disposed inside the hole. If the water-retaining material is present inside the hole in addition to the granular material, the amount of water to be sprayed on the granular material in the hole can be reduced, and the frequency of water spraying can be reduced. The water-retaining material is granular. For convenience of processing, the water-retaining material may be, for example, a rectangular parallelepiped shape, but even in that case, the condition of "granular" as referred to in this application is satisfied. The reason for making the water-retaining material granular is to prevent the water-retaining material from causing clogging in the hole as described above, as in the case of granular material. The size of the water-retaining material is preferably, for example, a block shape with a side of about 5 cm to 10 cm. If the size of the water-retaining material is about this size, clogging as described above is unlikely to occur. The water-retaining material can be, for example, a sponge. More specifically, the water-retaining material can be a PVA (polyvinyl alcohol) sponge. The amount of the water-retentive material is preferably 5% to 20% of the granules in terms of volume ratio (volume ratio when the water-retentive material is not crushed by external force). By keeping the amount of the water-retentive material within the above range relative to the granules, it is possible to simultaneously ensure breathability, improve evaporative cooling efficiency, and reduce the amount of water used.

The area of the opening of the hole exposed to the external environment and the area of the opening exposed to the indoor space can both be three times or more the cross-sectional area of the exhaust port.
By doing this, even if there is no ventilation equipment such as a fan in the flow path formed by the hole for supplying air from the external environment to the indoor space, air can be efficiently supplied to the indoor space through the hole by discharging air from the indoor space to the external environment with the exhaust device.
A plate may be disposed inside the hole to partition the space inside the hole, in order to lengthen the flow path of air drawn from the external environment to the indoor space, from the opening exposed to the external environment side of the hole to the opening exposed to the indoor space side. By lengthening the flow path, the air comes into contact with more granular matter on the way from the external environment to the indoor space, so that the air temperature is further reduced. A part of the plate may protrude from the hole, in other words, be exposed to the ground surface.

The present inventors also propose, as one aspect of the present invention, a facility equipped with the above-mentioned cooling system. The effects of such a facility are equivalent to those of the cooling system described above.
An example facility is one that has partitions to separate interior spaces from the outside environment.
This facility is equipped with a cooling system for cooling the indoor space of the facility, including an exhaust device arranged in the partition and having an exhaust port that connects the indoor space with the external environment and disposes of air from the indoor space to the external environment, a hole formed in the ground at the edge of the facility that connects the indoor space with the external environment and straddles the indoor space and the external environment when viewed in a plane, granular material arranged inside the hole, and a sprinkler device for sprinkling water on the granular material inside the hole.

FIG. 1 is a perspective view showing a facility according to an embodiment. FIG. 2 is a side cross-sectional view of the facility shown in FIG. 1 . FIG. 2 is a perspective plan view of the facility shown in FIG. 1 .

A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

The facility according to this embodiment is as shown in the perspective view of Figure 1, the side cross-sectional view of Figure 2, and the plan view of Figure 3. Note that Figure 1 does not show the sprinkler system, sensors, connection lines, control panel, and granular material, which will be described later.

The facility 10 includes a building 11. The building 11 may be publicly known or well-known, and in this embodiment, a well-known structure is adopted. Although not limited thereto, the building 11 in this embodiment is a horticultural facility, and more specifically, a greenhouse for horticulture. However, the building 11 does not have to be a horticultural facility, and may be, for example, a factory or a warehouse.
The building 11 is configured to include walls 12 and a roof 13. As is well known or well-known, the walls 12 and the roof 13 are structures that are supported by foundations, columns, beams, etc. and have a guaranteed rigidity, but these are not shown in the present embodiment. Note that the building 11 may be a facility that does not have a foundation or roof and is composed mainly of pipes and covering materials (translucent sheets), which is widely used for agricultural purposes.
In this embodiment, the walls 12 are four walls that form a rectangle in plan view. In this embodiment, all of the four walls 12 are rectangular, and, although not limited thereto, all of the walls 12 have the same height. The roof 13 is rectangular in plan view, and its four sides overlap the top edges of the four walls 12. In this embodiment, the roof 13 is horizontal, but the roof 13 does not need to be flat. The space surrounded by the inner surfaces of the four walls 12, the lower surface of the roof 13, and the ground surface is the indoor space 15 of the facility 10 referred to in this application. The indoor space 15 is separated from the external environment. Although not limited thereto, the indoor space 15 in this embodiment has a rectangular parallelepiped shape.
As described above, the facility 10 in this embodiment is a horticultural greenhouse, and plants are grown in the interior space 15. In this embodiment, the walls 12 and the roof 13 are both made of a transparent material, for example, a glass plate, so that light necessary for growing plants (sunlight in this embodiment) can be introduced into the interior space 15. Of course, if the facility 10 is not a horticultural greenhouse, or for other reasons, and there is no need to introduce sunlight into the interior space 15, the walls 12 and the roof 13 do not need to be made of a transparent material.
In this embodiment, the facility 10 has a rectangular shape with short sides of about 5 to 10 m and long sides of about 20 to 40 m when viewed from above, but this is not limited to this. In particular, when the facility 10 is a factory or warehouse, the long side may exceed 100 m.
The plants may be planted on the ground surface that corresponds to the floor of the indoor space 15 of the facility 10, or may be planted in a planter or other equipment. If the plants are not planted on the ground surface that is the floor of the facility 10, the floor of the indoor space 15 does not need to have an exposed ground surface, and may be covered with, for example, a predetermined flooring material.
The facility 10 may have, for example, a door on one of its walls 12 for accessing the indoor space 15, and may also have other necessary equipment, for example, publicly known or well-known equipment. Since these are hardly related to the present invention, they will not be shown in the drawings, and they will not be described.

The following components provided in the facility 10 are components for cooling the facility 10 and constitute the cooling system of the present invention.

An exhaust device 20 is provided at a predetermined location on the wall 12 or roof 13 of the facility 10, which is not limited to this location, but in this embodiment, is provided at approximately the center of the wall 12, which corresponds to one of the short sides of the facility 10 when viewed in a plan view.
The exhaust device 20 has an exhaust port 21 which is a hole. The exhaust port 21 is a hole for communicating the indoor space 15 with the external environment. The exhaust device 20 also has a fan 22. The fan 22 is a blower that exhausts the air in the indoor space 15 to the external environment through the exhaust port 21. The configurations of the exhaust port 21 and the fan 22 may be publicly known or well-known, and commercially available ones may suffice. Although one exhaust device 20 is provided in this embodiment, two or more exhaust devices 20 may be provided.
A sensor 31 is provided at an appropriate position in the indoor space 15 of the facility 10. The sensor 31 measures the temperature of the indoor space 15. The sensor 31 is connected to a control panel 33 by a predetermined connection line 32. The sensor 31 detects the temperature of the indoor space 15 in real time, for example, and sends temperature data on the detected temperature to the control panel 33 via the connection line 32. The control panel 33 controls the exhaust device 20, more specifically, the fan 22, based on the temperature data input from the sensor 31. How the control panel 33 controls the fan 22 based on the temperature data will be described later.

At a predetermined location across the wall 12 of the facility 10, a hole 40 is provided by digging into the ground. The hole 40 serves as an air flow path for supplying air from the external environment into the indoor space 15 of the facility 10.
The hole 40 straddles the wall 12 in plan view. In this embodiment, the wall 12 that the hole 40 straddles is the wall 12 opposite the wall 12 on which the exhaust device 20 is provided. In order to evenly lower the air temperature in the indoor space 15, it is advantageous for the exhaust device 20 and the hole 40 to be positioned as far apart as possible within the facility 10 in plan view. From this perspective, in this embodiment, the hole 40 is provided in the above position, but this is not necessarily required.
The hole 40 is made by digging the ground surface, and the soil is left exposed on its inner surface, although this is not necessarily the case. To prevent the wall of the hole 40 from collapsing, for example, it may be reinforced with a known or well-known net, but if the water supplied from the soil to the inside of the hole 40 is to be used in the same way as the water sprinkled, as described below, the inner surface of the hole 40 should not be waterproofed, for example by covering the inner surface of the hole 40 with a concrete layer.
In this embodiment, the hole 40 is rectangular in plan view and has an approximately rectangular parallelepiped shape as a whole, but these are not essential. In this embodiment, each side of the rectangular opening of the hole 40 is parallel to the long side or short side of the facility 10. Since the hole 40 straddles the wall 12, the opening of the hole 40 has a part located outside the wall 12 and opening to the external environment, and a part located inside the wall 12 and opening to the indoor space 15. The areas of the opening of the hole 40, the part opening to the external environment and the part opening to the indoor space 15, may or may not be the same, but if the difference between the two is large, the narrower opening may function as a bottleneck when viewed as an air flow path, so it is preferable that the areas of both are the same or at least the larger area is about 1.5 times the area of the smaller area. In addition, it is preferable that the areas of the opening of the hole 40, the part opening to the external environment and the part opening to the indoor space 15 are both three times or more the area of the exhaust port 21 in the exhaust device 20, although this is not limited to this, in this embodiment. By setting the areas of the opening of the hole 40 that opens to the outside environment and the opening of the hole 40 that opens to the indoor space 15 as described above, air can be drawn into the indoor space 15 through the hole 40 by only the function of the fan 22 in the exhaust device 20. If there are multiple exhaust devices 20, it is preferable that the areas of the opening of the hole 40 that opens to the outside environment and the opening of the hole 40 that opens to the indoor space 15 are both three times or more the sum of the areas of the multiple exhaust ports 21.

Although not necessarily limited to this, in this embodiment, a plate 41 is arranged inside the hole 40 to divide the space inside the hole 40 in order to lengthen the flow path of air drawn from the external environment to the indoor space 15, from the opening exposed to the external environment side of the hole 40 to the opening exposed to the indoor space 15 side.
There is no particular limitation on the material of the plate 41, and it may be made of wood or metal, for example. Despite its name, the plate 41 may be a membrane material as long as it does not allow air to pass through. In this embodiment, the plate 41 is rectangular and arranged vertically. The width of the plate 41 extends over the entire length of the width direction of the hole 40 (the length direction of the wall 12 that the hole 40 spans when viewed in plan). The upper side of the plate 41 is located on the plane on which the opening of the hole 40 is placed, and the lower side of the plate 41 is floating above the bottom of the hole 40. Therefore, air passing from the external environment through the hole 40 toward the indoor space 15 cannot reach the indoor space 15 without passing under the plate 41 (see the arrow in the hole 40 in FIG. 2). Therefore, due to the presence of the plate 41, the flow path formed inside the hole 40 for the air supplied from the external environment to the indoor space 15 is forcibly longer than when the plate 41 is not present.
The upper side of the plate 41 may extend to a position higher than the opening of the hole 40. In this embodiment, the plate 41 is located almost directly below the wall 12 that the hole 40 spans, but this is of course not limited to this.
The depth of the hole 40 is determined according to the length of the above-mentioned flow path to be formed in the hole 40. Of course, the deeper the hole 40, the longer the flow path. The depth of the hole 40 must naturally be deeper than the depth reached by the lower side of the plate 41. The distance between the lower side of the plate 41 and the bottom of the hole 40 must be sufficiently wide so that the gap is not too narrow and the flow path does not function as an air flow path. Whether the plate 41 is present or not, the depth of the hole 40 is, for example, 2 to 3 m, and in many cases does not reach 10 m.

Granular material 42 is disposed inside hole 40. Granular material 42 may or may not be disposed inside hole 40 all the way to the edge of hole 40. However, if plate 41 is present, granular material 42 must be disposed at least up to a position higher than the lower edge of plate 41. Otherwise, air may reach indoor space 15 from the external environment without coming into contact with granular material 42, which may result in a lack of sufficient cooling effect, which will be described later.
The material of the granular material 42 is not particularly limited, but may be, for example, stone. It is preferable that the stone has high water retention, and therefore a high porosity is preferable. In general, the type of stone is preferably sedimentary rock rather than igneous rock. If the granular material 42 is stone, it may be possible in some cases to procure the granular material 42 from the site where the facility 10 is located or from its surroundings, and if this is possible, the cost required for constructing the facility 10 can be reduced.
The granular material should not be too fine. It is necessary to set the size so that a space is left in the hole 40 or a gap is left between adjacent granular material 42, so that the phenomenon of air in the external environment being drawn into the indoor space 15 through the hole 40 is not prevented when the air in the indoor space 15 is exhausted to the external environment by the exhaust device 20. The size of the granular material 42 can be selected from a range in which the diameter of the granular material 42 is about 10 to 20 cm, for example. The size and shape of each granular material 42 do not need to be uniform. For example, when the granular material 42 is a stone, especially when it is crushed stone, it is normal for the size and shape of each granular material 42 to be irregular. The size and shape of the granular material 42 are irregular, because it is easier to create gaps between adjacent granular materials 42 in the hole 40, and this is preferable for the hole 40 to function as an air flow path.
In addition to the granular material 42, a granular water-retaining material having water-retaining properties may be disposed inside the hole 40. Although not shown in the drawings, this is the case in this embodiment, although this is not necessarily the case. If the water-retaining material is present inside the hole 40 in addition to the granular material 42, the amount of water to be sprayed on the granular material 42 in the hole can be reduced as described below, and the frequency of water spraying can be reduced. The water-retaining material is granular. This is to prevent the water-retaining material from causing clogging in the hole 40 as described above, as in the case of the granular material 42. The size of the water-retaining material is preferably about half that of the main granular material 42, for example. The water-retaining material can be a rectangular parallelepiped with a side length of about 5 cm to 10 cm, for example, and this is the case in this embodiment. Of course, the size and shape of the water-retaining material are not limited to this. If the size of the water-retaining material is about this size, air will flow easily inside the hole 40, and air will be smoothly supplied from the external environment to the indoor space 15.
The water retention material is a solid, and may be, for example, a sponge. More specifically, the water retention material may be a PVA (polyvinyl alcohol) sponge. The amount of the water retention material is preferably 5% to 20% of the granular material 42 in terms of volume ratio (volume ratio when the water retention material is not crushed by external force). By keeping the amount of the water retention material within the above range relative to the granular material 42, it is possible to simultaneously ensure breathability, improve evaporative cooling efficiency, and reduce the amount of water used.

The facility 10 is provided with a sprinkler system 50 .
The water sprinkler 50 is for sprinkling water onto the granular material 42 (and the water retention material; hereinafter, the granular material 42 and the water retention material may be collectively referred to as "granular material 42, etc.") in the hole 40. As long as such function is guaranteed, the configuration of the water sprinkler 50 is not important, and the location where the water sprinkler 50 is attached is also not important. The water sprinkler 50 may be a known or well-known device, or may be a commercially available device.
In this embodiment, the water sprinkler system 50 is attached to the exterior surface of the wall 12 that the hole 40 spans, but this is not limited thereto.
When the water sprinkler 50 sprinkles water on the granular matter 42 etc. in the hole 40, the water may be supplied in the form of droplets or in the form of a finer mist.
The water supply from the water sprinkler 50 to the granular material 42 etc. may be performed constantly or in a batch manner. When water is supplied in a batch manner, the water sprinkler 50 may perform water sprinkling automatically, or the water sprinkler 50 may be manually operated.
The amount of water that the water sprinkler 50 should supply to the granular material 42 etc. in the hole 40 is an amount that allows the granular material 42 to maintain a moisture level equivalent to the water absorption capacity of the granular material 42. Since the granular material 42 that is completely submerged in water will no longer come into contact with the air passing through the hole 40 from the external environment toward the indoor space 15, and will no longer produce the cooling effect of the air by evaporative cooling, which will be described later, it is preferable to adjust the amount of water supplied so that the granular material 42 at the bottom of the hole 40 is not submerged. In particular, if water accumulates at the bottom of the hole 40 and the water level exceeds the lower edge of the plate 41, the air flow path in the hole 40 that connects the external environment to the indoor space 15 will be cut off, and it is necessary to prevent such a situation from occurring.

The method of use and operation of the facility 10 described above will now be described.
As described above, plants are grown in the facility 10 in this embodiment. The facility 10 is assumed to be in a high temperature region or to be used during high temperature periods, and is in a situation where the air temperature in the indoor space 15 needs to be lowered below that of the external environment. In such a case, the air temperature in the indoor space 15 is lowered as follows.

First, the water sprinkler 50 sprinkles water into the hole 40. In this embodiment, water is sprinkled in a mist state into the hole 40, although this is not limited thereto. Although this is not limited thereto, water sprinkling is performed on substantially the entire portion of the opening of the hole 40 that opens to the external environment. The mist water enters the hole 40 and adheres to the surface of the granular material 42, which is a stone (a small amount of water enters the inside of the stone and is retained), and also soaks into the water-retaining material, which is a PVA sponge. As a result, the surface of the granular material 42 is kept moderately moist. When water sprinkling is performed with the fan 22 of the exhaust device 20 driven, an air flow from the external environment to the indoor space 15 is generated in the air flow path in the hole 40. When water is sprinkled in a mist state, small water particles flow along the air flow path in the hole 40, so that it is possible to moderately moisten the surface of the granular material 42 in the entire range of the hole 40.
In this embodiment, the sprinkler 50 sprinkles water in batches when the surface of the granular material 42 becomes insufficient in moisture. For example, the sprinkler 50 can be configured to automatically sprinkle water every time a predetermined amount of air is supplied from the external environment to the indoor space 15. The sprinkler 50 may simply be configured to automatically sprinkle water at predetermined time intervals. When water is supplied from the ground into the hole 40, it is possible to reduce the amount of water sprinkled by the sprinkler 50. It is preferable that the sprinkler 50 sprinkles water so that the surface moisture of the granular material 42 is kept within a certain range, and this is done in this embodiment.

As described above, the surface of the granular material 42 in the hole 40 is in a moderately moist state. This state is easily maintained by the presence of the water-retentive material that has absorbed moisture.
In this state, the fan 22 of the exhaust device 20 is driven. The fan 22 may be driven continuously or may be driven batchwise. The driving state of the fan 22 (the amount of air per unit time exhausted from the exhaust port 21 to the external environment) may be constant or may vary over time. In this embodiment, although not limited to this, the fan 22 is driven continuously, but the driving state of the fan 22 is controlled by the control panel 33. A method of controlling the driving state of the fan 22 will be described later.

When the fan 22 in the exhaust device 20 is driven, the air in the indoor space 15 is exhausted to the outside environment through the exhaust port 21 (see the rightmost arrow in FIG. 2).
Then, the pressure inside the indoor space 15 is temporarily negative, and the air that was discharged is taken in from the external environment into the indoor space 15 through the hole 40. The air in the external environment enters the hole 40 from the portion of the opening of the hole 40 that opens to the external environment, flows downward, passes under the plate 41 inside the hole 40, and then exits into the indoor space 15 from the portion of the opening of the hole 40 that opens to the indoor space 15. In this way, air is supplied from the external environment to the indoor space 15. As already mentioned, the flow path of the air inside the hole 40 is shown by the arrows inside the hole 40 in FIG. 2.
As a result, in the indoor space 15, as shown by the arrow slightly to the left of the center of the indoor space 15 in FIG. 2, an air flow is generated from the left to the right in FIG.
The air entering from the external environment and flowing through the holes 40 as described above comes into contact with the numerous granular materials 42 and water-retaining material in the holes 40. At this time, the water attached to (or retained in) the granular materials 42 etc. evaporates, and the resulting evaporative cooling effect makes the air temperature lower than when the air was in the external environment. Therefore, the air supplied to the indoor space 15 is supplied to the indoor space 15 in a cooled state. In other words, the holes 40 have a cooling effect on the air supplied to the indoor space 15.

As described above, the indoor space 15 is provided with a sensor 31 that detects the temperature of the air in the indoor space 15. In this embodiment, although not limited thereto, the sensor 31 constantly generates temperature data that is data relating to the temperature of the air in the indoor space 15 and sends the data to the control panel 33 via a connection line 32.
The control panel 33 receives the temperature data and changes the driving state of the fan 22 of the exhaust device 20. In this embodiment, the control panel 33 drives the fan 22 at a constant strength when the temperature data indicates that the temperature of the indoor space 15 is between two different temperatures, a first temperature and a second temperature higher than the first temperature. On the other hand, when the temperature data indicates that the temperature of the indoor space 15 is lower than the first temperature, the control panel 33 controls the fan 22 to drive less (to reduce the amount of air exhausted from the exhaust port 21 to the external environment), and when the temperature data indicates that the temperature of the indoor space 15 is higher than the second temperature, the control panel 33 controls the fan 22 to drive more (to increase the amount of air exhausted from the exhaust port 21 to the external environment).
With this control, air is constantly being exhausted from the exhaust port 21 in the indoor space 15, and air is constantly being exchanged by taking in air through the hole 40. Furthermore, when the temperature of the indoor space 15 rises, the fan 22 is driven strongly to promote the exchange of air, thereby cooling the air in the indoor space 15, and when the temperature of the indoor space 15 rises, the fan 22 is driven weakly to suppress the exchange of air, thereby suppressing the cooling of the air in the indoor space 15. As a result, the temperature of the air in the indoor space 15 is kept within a constant range.
However, the driving state of the fan 22 is not limited to the above-mentioned three types, and the fan 22 may be driven in more types of states. Of course, the driving state of the fan 22 may be changed steplessly.
In addition, it is also possible to change the driving state of the fan, for example, by applying inverter control, regardless of the change in temperature of the indoor space 15. It is known that plants have a better effect if the wind blowing on them is not constant, and such control may have a positive effect on the growth of the plants. Of course, even if the control panel 33 performs such control, the above-mentioned flow in which the air in the indoor space 15 is exhausted to the outside environment through the exhaust port 21 and the air of the outside environment is supplied to the indoor space 15 through the hole 40, and the phenomenon in which the air supplied from the outside environment to the indoor space 15 is cooled in the hole 40, continue to occur.

REFERENCE SIGNS LIST 10 Facility 11 Building 12 Wall 13 Roof 20 Exhaust device 21 Exhaust port 22 Fan 31 Sensor 33 Control panel 40 Hole 41 Plate 42 Granular material 50 Sprinkler system

Claims (7)

1. A cooling system for cooling an indoor space of a facility having a partition wall for isolating the indoor space from an external environment, comprising:
an exhaust device that exhausts air from the indoor space to an external environment and has an exhaust port that is disposed in the partition wall and communicates the external environment with the indoor space;
A hole provided in the ground at the edge of the facility so as to straddle the indoor space and the external environment when viewed in a plan view, which connects the indoor space and the external environment;
A granular material disposed inside the hole;
A water sprinkler for sprinkling water on the granular material inside the hole;
Equipped with
In addition to the granular material, a granular water-retaining material having water-retaining properties is disposed inside the hole.
Cooling system. The particulate matter is stone.
The cooling system of claim 1 . The water-retaining material is a sponge.
The cooling system of claim 1 . The water-retaining material is 5% to 20% by volume of the granular material.
The cooling system according to claim 1 or 3 . The area of the opening of the hole exposed to the external environment side and the area of the opening exposed to the indoor space side are both three times or more the cross-sectional area of the exhaust port.
The cooling system of claim 1 . A plate is disposed inside the hole, dividing the space inside the hole, from an opening exposed to the external environment side of the hole to an opening exposed to the indoor space side, in order to lengthen the flow path of air drawn from the external environment to the indoor space.
The cooling system according to claim 1 or 5 . A facility having a partition wall for isolating an indoor space from an external environment,
an exhaust device that exhausts air from the indoor space to an external environment and has an exhaust port that is disposed in the partition wall and communicates the external environment with the indoor space;
A hole provided in the ground at the edge of the facility so as to straddle the indoor space and the external environment when viewed in a plan view, which connects the indoor space and the external environment;
A granular material disposed inside the hole;
A water sprinkler for sprinkling water on the granular material inside the hole;
a cooling system for cooling the indoor space of the facility, comprising :
In addition to the granular material, a granular water-retaining material having water-retaining properties is disposed inside the hole.
facility.

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