Air-conditioning system and crop plant raising system

Abstract

To provide an air-conditioning system or the like capable of supplying conditioned air to crop plants more uniformly.SOLUTION: An air-conditioning system is provided. The air-conditioning system comprises: an air-conditioning unit which sends out conditioned air; a first ventilation duct; a second ventilation duct; and air blowers provided for the second ventilation duct. The first ventilation duct is provided at a position lower than the height of crop plants in a raising space for raising the crop plants. The second ventilation duct is provided at a position higher than the height of the crop plants in the raising space. The air-conditioning unit is installed in an air-conditioning space having a partition between the raising space and the air-conditioning space, and sends out conditioned air into the first ventilation duct. The first ventilation duct discharges the sent-out conditioned air into the raising space. The air blowers send air in the raising space into the second ventilation duct, and the second ventilation duct discharges air sent from the air blowers into the air-conditioning space.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air conditioning system and a crop cultivation system. [Background technology]

[0002] Patent Document 1 discloses a technique for taking in air from inside a vinyl greenhouse, dehumidifying it, and then sending the dehumidified air into the greenhouse using a blower. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 5-90220 Summary of the Invention [Problem to be solved by the invention]

[0004] When conditioned air, such as dehumidified air, is supplied to a space for growing crops, such as a vinyl greenhouse, uneven air conditions within the space can lead to uneven growth of the crops.

[0005] In view of the above circumstances, the present invention provides an air conditioning system and the like that can supply conditioned air to crops more uniformly. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an air conditioning system. The air conditioning system includes an air conditioning unit that delivers conditioned air, a first ventilation duct, a second ventilation duct, and a blower provided in the second ventilation duct. The first ventilation duct is provided in a growing space where crops are grown, at a position lower than the height of the crops. The second ventilation duct is provided in the growing space at a position higher than the height of the crops. The air conditioning unit is installed in an air-conditioned space having a partition between it and the growing space, and delivers the conditioned air into the inside of the first ventilation duct. The first ventilation duct exhausts the delivered conditioned air into the growing space. The blower delivers air from the growing space into the inside of the second ventilation duct, and the second ventilation duct exhausts the air delivered by the blower into the air-conditioned space.

[0007] According to this embodiment, conditioned air can be supplied to the crops more uniformly. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the overall configuration of a crop growing system 1. [Diagram 2] FIG. 2 is a diagram showing an example of the crop cultivation system 1 as viewed in the depth direction. [Diagram 3] FIG. 2 is a diagram showing an example of the growth space S1 as viewed vertically from above. [Figure 4] FIG. 13 is a diagram showing a comparative example of the growth space S1 as viewed vertically from above. [Diagram 5] FIG. 4 is a diagram showing an example of a first rotation speed table. [Figure 6] FIG. 4 is a diagram showing an example of a second rotation speed table. [Figure 7] FIG. 13 is a diagram showing an example of a third rotation speed table. [Figure 8] FIG. 13 is a diagram showing an example of a fourth rotation speed table. [Figure 9] FIG. 13 is a diagram showing an example of a fifth rotation speed table. [Figure 10] FIG. 13 is a diagram showing an example of a sixth rotation speed table. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various characteristic features shown in the following embodiments can be combined with each other.

[0010] <Embodiment> FIG. 1 is a diagram showing an example of the overall configuration of a crop cultivation system 1. In FIG. 1, a three-dimensional coordinate system is shown by arrows indicating the X-axis, Y-axis, and Z-axis, respectively. Hereinafter, the X-axis direction, the Y-axis direction, and the Z-axis direction will be referred to as the left-right direction, the depth direction, and the up-down direction, respectively. The crop cultivation system 1 is a system for cultivating crops while adjusting the environment in a space isolated from an external space S4. The crop cultivation system 1 includes a pipe house 10 and an air conditioning system 20.

[0011] The pipe greenhouse 10 is a structure that forms a growing space S1 for growing crops. The growing space S1 is longer in the depth direction than in the left-right direction. In the growing space S1, crops are grown in rows along the depth direction. The pipe greenhouse 10 has pipes that form the framework and a transparent coating that covers the framework. The pipes are made of strong materials such as steel, and the coating is made of a transparent material such as vinyl.

[0012] The pipe greenhouse 10 forms an air-conditioned space S2 in addition to the growing space S1. The air-conditioned space S2 is adjacent to the end of the growing space S1 in the depth direction, and has a partition 11 between it and the growing space S1. The growing space S1 and the air-conditioned space S2 are connected so that air can circulate. The air-conditioning system 20 is a system that supplies conditioned air to crops while circulating air between the growing space S1 and the air-conditioned space S2. The conditioned air is air whose temperature, humidity, or carbon dioxide concentration, for example, has been adjusted to promote the growth of crops, and is hereinafter referred to as "conditioned air."

[0013] The air conditioning system 20 includes an air conditioner 21, a gas cylinder 22, a blower fan 23, a supply duct 24, a plurality of return duct fans 25, a return duct 26, a first intake fan 27, a second intake fan 28, a bypass duct 29, a control unit 30, and a differential pressure gauge 31. The air conditioner 21 has an outdoor unit (not shown) and delivers air whose temperature, humidity, air volume, etc. have been adjusted. The gas cylinder 22 is a container filled with liquefied carbon dioxide gas, and releases carbon dioxide by opening a valve. The carbon dioxide released by the gas cylinder 22 is mixed into the air delivered by the air conditioner 21, and the air containing a large amount of carbon dioxide is supplied to the blower fan 23 as conditioned air.

[0014] The blower fan 23 rotates to generate an air current that sends the conditioned air supplied from the air conditioner 21 and the gas cylinder 22 into the supply duct 24. The supply duct 24 is a long, thin, cylindrical member for transporting gas, and is provided along the depth direction. The supply duct 24 has openings at regular intervals, and the conditioned air sent in is discharged from these openings. The movement path of the conditioned air discharged from the supply duct 24 will be described with reference to FIG. 2.

[0015] FIG. 2 is a diagram showing an example of the crop cultivation system 1 seen in the depth direction. The supply duct 24 is installed so as to be in contact with waterproof vinyl laid on the ground. The waterproof vinyl is not essential, and the supply duct 24 may be installed directly on the ground. Meanwhile, the return duct fan 25 is installed at a position higher than the height of the crops, and rotates the fan to generate an airflow toward the inside of the return duct 26. The height of the crops here means the height of the crops when they have grown to their highest. It is expected that an airflow will be generated from the supply duct 24 toward the return duct fan 25 due to the airflow of the conditioned air discharged by the supply duct 24 and the airflow generated by the return duct fan 25. FIG. 2 shows a typical movement path R1 of this airflow.

[0016] Movement path R1 is a path from the supply duct 24 to the return duct fan 25. The supply duct 24 and the return duct fan 25 are arranged so that this movement path R1 passes near the center of the crop. By arranging the supply duct 24 and the return duct fan 25 in this manner, the conditioned air discharged from the supply duct 24 can be moved so as to come into contact with as wide an area of ​​the surface of the crop as possible.

[0017] Conditioned air contains more carbon dioxide than normal air, and therefore promotes photosynthesis compared to when normal air is absorbed. The state of the conditioned air changes when it acts to promote crop growth. For example, in the case of the above-mentioned conditioned air, the crops that have undergone photosynthesis release oxygen, and the state changes from one that contains a lot of carbon dioxide to one that contains a lot of oxygen with less carbon dioxide. Air that has changed state in this way is hereinafter referred to as "changed air." Note that the temperature, humidity, etc. of the changed air may also have changed.

[0018] The return duct 26 is a long, thin cylindrical member for transporting gas. The converted air sucked into the return duct 26 passes through the inside of the return duct 26 and moves to the air-conditioned space S2. The converted air that moves to the air-conditioned space S2 is conditioned again by the air conditioner 21 and the gas cylinder 22, and is supplied to the growing space S1 from the supply duct 24 as conditioned air. In this way, the air conditioner 21, the blower fan 23, and the return duct fan 25 work together to circulate the air in the growing space S1 and the air-conditioned space S2.

[0019] The pipe house 10 is provided with a first intake fan 27. The first intake fan 27 rotates to generate an airflow that takes in outside air from the external space S4 into the air-conditioned space S2. The first intake fan 27 operates to take in and cool the outside air when the temperature in the air-conditioned space S2 becomes too high, for example.

[0020] In addition, since the covering of the pipe greenhouse 10 is made of a soft material such as vinyl, any pressure difference between the growing space S1 and the air-conditioned space S2 may cause damage. The differential pressure gauge 31 is a sensor that measures the pressure difference between the growing space S1 and the air-conditioned space S2. The first intake fan 27 operates to take in outside air and reduce the pressure difference, for example, when the pressure difference measured by the differential pressure gauge 31 becomes too large.

[0021] The light control screen 32 is a screen that has a function of adjusting the amount of sunlight that reaches the crops. The light control screen 32 is provided vertically above the return duct 26, and serves as the vertically upper boundary of the growing space S1. An upper space S3 is formed vertically above the light control screen 32. The light control screen 32 serves to suppress the movement of air between the growing space S1 and the upper space S3. Therefore, air circulation in the growing space S1 and air circulation in the upper space S3 are performed separately.

[0022] The second intake fan 28 rotates to generate an airflow that sends outside air into the bypass duct 29. The bypass duct 29 is a long, thin, cylindrical member for transporting gas, and connects the external space and the upper space S3. Therefore, by operating the second intake fan 28, the outside air is sent from the external space S4 to the upper space S3.

[0023] In the cultivation space S1, the amount of light can be reduced by the light control screen 32 to prevent the temperature from rising, but in the upper space S3, the amount of light cannot be adjusted, so the temperature is more likely to rise than in the cultivation space S1. Therefore, the upper space S3 is designed to take in outside air directly from the bypass duct 29, so that the rise in temperature can be prevented without affecting the circulation of the conditioned air.

[0024] The pipe house 10 has an exhaust window 12 on the roof vertically above. The exhaust window 12 is, for example, a pneumatically driven exhaust window that opens passively when the air pressure inside the pipe house 10 rises to exhaust air. The air taken in by the second intake fan 28 is exhausted from the exhaust window 12 to prevent an excessive increase in air pressure in the upper space S3. Also, when the first intake fan 27 takes in outside air, the air pressure in the air-conditioned space S2 and the cultivation space S1 rises accordingly, so the air taken in is exhausted from the exhaust window 12 to prevent an excessive increase in air pressure in the air-conditioned space S2 and the cultivation space S1.

[0025] The air conditioner 21 and the gas cylinder 22 described above are an example of an air conditioning unit that sends out conditioned air. The supply duct 24 is an example of a first ventilation duct provided at a position lower than the height of the crops in the growing space S1 where the crops are grown. The return duct 26 is an example of a second ventilation duct provided at a position higher than the height of the crops in the growing space S1. The return duct 26 is provided with a return duct fan 25. The return duct fan 25 is an example of a blower that sends air from the growing space S1 into the return duct 26.

[0026] The air conditioning system 20 includes an air conditioner 21, a gas cylinder 22 (an example of an air conditioning unit), a supply duct 24 (an example of a first ventilation duct), a return duct 26 (an example of a second ventilation duct), and a return duct fan 25 (an example of a blower). The air conditioner 21 and the gas cylinder 22 are installed in an air-conditioned space S2 having a partition 11 between them and the growth space S1, and send out conditioned air into the supply duct 24. The supply duct 24 exhausts the conditioned air that has been sent out to the growth space S1. The return duct fan 25 sends air from the growth space S1 into the return duct 26, and the return duct 26 exhausts the air sent in by the return duct fan 25 to the air-conditioned space S2.

[0027] Since the cultivation space S1 is long in the depth direction, without the return duct 26, the air discharged from the supply duct 24 does not easily return to the air-conditioned space S2. Therefore, the farther the space is from the air-conditioned space S2, the more likely it is that the changed air discharged from the crops will remain above the crops, and the changed air will mix with the conditioned air and be sucked into the crops. Therefore, by providing the return duct fan 25 and the return duct 26, the changed air is less likely to remain compared to when these are not provided, and conditioned air can be supplied to the crops more efficiently.

[0028] Moreover, the growth space S1 has a shape with a defined longitudinal direction and a lateral direction when viewed vertically from above. Fig. 3 is a diagram showing an example of the growing space S1 as viewed from vertically above. In the crop growing system 1 shown in Fig. 3, the growing space S1 has a rectangular shape with the depth direction as the longitudinal direction and the left-right direction as the short side direction. The air-conditioned space S2 is adjacent to one end of the growing space S1 in the longitudinal direction. The supply duct 24 (an example of a first ventilation duct) and the return duct 26 (an example of a second ventilation duct) are provided along the longitudinal direction from one end of the growing space S1 to a position farther from the one end than the center C1 of the growing space S1.

[0029] Two supply ducts 24 are provided at the left and right ends, and each has openings 41, 42, 43, . . . , 47, and 48 (referred to as "opening 40" when there is no need to distinguish between them). One return duct 26 is provided in the center in the left and right direction, and has return duct fans 25-1, 25-2, 25-3, . . . , 25-7, and 25-8 (referred to as "return duct fans 25" when there is no need to distinguish between them).

[0030] Each of the multiple openings 40 is provided with a corresponding return duct fan 25 at a position that is the same distance from the air-conditioned space S2 in the depth direction. For example, the opening 41 is provided with a return duct fan 25-1, and the opening 48 is provided with a return duct fan 25-8. A portion of the conditioned air discharged from each opening 40 is absorbed by the crops and becomes converted air, which is sent to the return duct 26 by the corresponding return duct fan 25. In FIG. 3, the path of the air circulating in this manner is indicated by a dashed line.

[0031] Here, a comparative example in which the return duct 26 is short will be described. Fig. 4 is a diagram showing a comparative example of the cultivation space S1 as viewed from vertically above. In the crop cultivation system 1a shown in Fig. 4, the supply duct 24 (an example of a first ventilation pipe) is provided along the longitudinal direction from one end of the cultivation space S1 to a position farther from the one end than the center C1 of the cultivation space S1, while the return duct 26 (an example of a second ventilation pipe) is provided along the longitudinal direction from one end of the cultivation space S1 only to a position closer to the one end than the center C1 of the cultivation space S1.

[0032] In the example of Fig. 4, air is circulated from the opening 41 to the opening 44 through the corresponding return duct fan 25-1 to the return duct fan 25-4. On the other hand, there is no corresponding return duct fan 25 from the opening 45 to the opening 48, so that the discharged conditioned air and the converted air including the air discharged by the crops are retained in a retention space D1 indicated by a two-dot chain line. In the crop cultivation system 1, as shown in Fig. 3, since the retention space D1 is not generated, the conditioned air can be circulated over a wider range of the cultivation space S1 compared to the case where the return duct 26 is short.

[0033] The crop cultivation system 1 includes the above-mentioned air conditioning system 20 and a pipe house 10. The pipe house 10 is an example of a structure that forms the cultivation space S1 and the air-conditioned space S2. As shown in FIG. 1, the crop cultivation system 1 also includes a first blower, a light control member, an exhaust port, and a second blower. The first intake fan 27 is an example of a first blower that takes in outside air into the air-conditioned space S2. The light control screen 32 is an example of a light control member that is provided vertically above the crops and adjusts the amount of light passing through.

[0034] The exhaust window 12 is an example of an exhaust port that exhausts air from the upper space S3 vertically above the light control screen 32. The second intake fan 28 is an example of a second blower that takes in outside air into the upper space S3. The second intake fan 28 (an example of a second blower) and the exhaust window 12 (an example of an exhaust port) replace the air in the upper space S3. Meanwhile, the supply duct 24 (an example of a first ventilation duct) and the return duct 26 (an example of a second ventilation duct) circulate the air in the cultivation space S1.

[0035] According to this embodiment, air can be exchanged separately above and below the light-adjusting member. For example, since the light-adjusting screen 32 blocks sunlight, the air in the growing space S1 is prevented from rising in temperature, but the air in the upper space S3 is more likely to rise in temperature than the air in the growing space S1 because the only thing blocking the sunlight is a transparent film. Therefore, by exchanging the air separately as described above, it is possible to more easily suppress the rise in temperature in the growing space S1 compared to when the air is exchanged together.

[0036] The control unit 30 is a computer that has a processor such as a Central Processing Unit (CPU) and a storage unit such as a storage device like a Solid State Drive (SSD) or a memory like a Random Access Memory (RAM). By reading a predetermined program stored in the storage unit, it realizes various functions related to the crop cultivation system 1. That is, the information processing by software stored in the storage unit is specifically realized by the control unit 30 which is an example of hardware, and can be executed as each functional unit included in the control unit 30. Note that the control unit 30 is not limited to being single, and may be implemented to have a plurality of control units 30 for each function, or a combination thereof may also be possible.

[0037] As shown in FIG. 3, the return duct 26 (an example of the second ventilation duct) is provided with a plurality of return duct fans 25 (an example of a blower). The control unit 30 functions as an example of a first control unit that controls the rotation speed of the plurality of return duct fans 25 according to the distance from one end of the cultivation space S1. Here, the one end mentioned refers to the end of the cultivation space S1 where the air-conditioned space S2 is adjacent, and hereinafter will be referred to as the "end on the air-conditioned space S2 side". The control unit 30 performs control using a first rotation speed table in which the distance from the end on the air-conditioned space S2 side and the rotation speed are associated.

[0038] FIG. 5 is a diagram showing an example of the first rotation speed table. The first rotation speed table TB1 shown in FIG. 5 associates the distances "D1", "D2", "D3", ···, "D7" and "D8" (D1 < D2 < D3 < ··· < D7 < D8) from the end on the air-conditioned space S2 side with the rotation speeds "RS1", "RS2", "RS3", ···, "RS7" and "RS8" for the return duct fans 25-1, 25-2, 25-3, ···, 25-7 and 25-8. Each rotation speed has, for example, a magnitude relationship of RS1 < RS2 < RS3 < ··· < RS7 < RS8.

[0039] The longer the distance from the end on the air-conditioned space S2 side, the longer the distance for returning the changed air to the air-conditioned space S2 through the return duct 26. Therefore, by increasing the rotational speed of the return duct fan 25, the amount of air circulated is made constant regardless of the distance from the end on the air-conditioned space S2 side, compared to the case where the rotational speed is uniform. As a result, compared to the case where the rotational speed is uniform, the changed air is less likely to stagnate regardless of the distance from the end on the air-conditioned space S2 side, and the adjusted air concentration in the cultivation space can be made more uniform.

[0040] Further, the control unit 30 functions as an example of a second control unit that controls the rotational speeds of the plurality of return duct fans 25 according to the rotational speed of the first intake fan 27 (an example of the first blower). The control unit 30 performs control using a second rotational speed table in which the rotational speed of the first intake fan 27 and the reference rotational speeds of the respective return duct fans 25 are associated. The reference rotational speed is, for example, the rotational speed of the return duct fan 25-1. The rotational speeds of the other return duct fans 25 are assumed to be the rotational speed obtained by adding a predetermined rotational speed to the reference rotational speed or the rotational speed obtained by multiplying the reference rotational speed by a predetermined count.

[0041] FIG. 6 is a diagram showing an example of the second rotational speed table. In the second rotational speed table TB2 shown in FIG. 6, the rotational speeds of the first intake fan 27 (RS11 < RS12 < RS13 < RS14) denoted as "RS11", "RS12", "RS13", and "RS14" are associated with the reference rotational speeds of the return duct fans 25 denoted as "RS21", "RS22", "RS23", and "RS24". Each reference rotational speed has, for example, a magnitude relationship of RS21 > RS22 > RS23 > RS24.

[0042] As the rotational speed of the first intake fan 27 increases, the air pressure in the air-conditioned space S2 rises, so the air pressure difference between the cultivation space S1 and the air-conditioned space S2 becomes larger. Therefore, as the rotational speed of the first intake fan 27 increases, the reference rotational speed is decreased to reduce the air returning from the cultivation space S1, thereby reducing the air pressure difference between the cultivation space S1 and the air-conditioned space S2 compared to the case where the reference rotational speed is uniform, and it is possible to suppress damage to the pipe house 10 due to this air pressure difference.

[0043] Further, the control unit 30 functions as an example of a third control unit that controls the rotational speeds of the plurality of return duct fans 25 according to the rotational speed of the second intake fan 28 (an example of a second blower). The control unit 30 performs control using a third rotational speed table in which the rotational speed of the second intake fan 28 and the reference rotational speeds of the respective return duct fans 25 are associated. The reference rotational speed and the rotational speeds of the other return duct fans 25 are the same as those described in the second rotational speed table.

[0044] FIG. 7 is a diagram showing an example of the third rotational speed table. The third rotational speed table TB3 shown in FIG. 7 associates the rotational speeds (RS31 < RS32 < RS33 < RS34) of the second intake fan 28, namely, "RS31", "RS32", "RS33", and "RS34", with the reference rotational speeds of the return duct fans 25, namely, "RS41", "RS42", "RS43", and "RS44". Each reference rotational speed has, for example, a magnitude relationship of RS41 > RS42 > RS43 > RS44.

[0045] As the rotation speed of the second intake fan 28 increases, the air pressure in the upper space S3 increases, and the air pressure difference between the growing space S1 and the upper space S3 increases. Here, the light control screen 32 does not completely separate the growing space S1 and the upper space S3, and some air circulates. Therefore, when this air pressure difference increases, the heated air in the upper space S3 is more likely to descend to the growing space S1. Therefore, as the rotation speed of the second intake fan 28 increases, the reference rotation speed is reduced to reduce the amount of air returning from the growing space S1, thereby reducing the air pressure difference between the growing space S1 and the upper space S3 compared to when the reference rotation speed is constant, and it is possible to suppress the air in the upper space S3 from descending to the growing space S1 due to this air pressure difference.

[0046] The control unit 30 also functions as an example of a fourth control unit that controls the rotation speeds of the multiple return duct fans 25 in response to the air pressure difference between the growing space S1 and the air-conditioned space S2. The control unit 30 performs control using a fourth rotation speed table that associates the air pressure difference between the growing space S1 and the air-conditioned space S2 with the reference rotation speed of each return duct fan 25. The reference rotation speed and the other rotation speeds of the return duct fans 25 are the same as those described in the second rotation speed table.

[0047] Fig. 8 is a diagram showing an example of the fourth rotation speed table. In the fourth rotation speed table TB4 shown in Fig. 8, the pressure differences between the cultivation space S1 and the air-conditioned space S2, namely "-E51", "-E52", "-E53", "-E54", "+E55", "+E56", "+E57", and "+E58" (-E51>-E52>-E53>-E54>0>+E55>+E56>+E57>+E58), are associated with the reference rotation speeds of the return duct fan 25, namely "RS51", "RS52", "RS53", "RS54", "RS55", "RS56", "RS57", and "RS58".

[0048] When the pressure difference is negative, it means that the pressure in the cultivation space S1 is lower, and when the pressure difference is positive, it means that the pressure in the cultivation space S1 is higher. In that case, each reference rotation speed has a magnitude relationship such as RS51 < RS52 < RS53 < RS54 < RS55 < RS56 < RS57 < RS58, for example. The control unit 30 controls such that, based on the pressure difference between the cultivation space S1 and the air-conditioned space S2 measured by the differential pressure gauge 31, the higher the pressure in the cultivation space S1 compared to the pressure in the air-conditioned space S2, the more the reference rotation speed is increased, and more air returning from the cultivation space S1 to the air-conditioned space S2 is increased.

[0049] Thus, the higher the pressure in the cultivation space S1 compared to the pressure in the air-conditioned space S2, the more air is sucked up from the cultivation space S1 to lower the pressure while air is sent into the air-conditioned space S2 to increase the pressure, making the pressure difference between the cultivation space S1 and the air-conditioned space S2 smaller compared to the case where the reference rotation speed is uniform. By such a mode, compared to the case where the control described in FIG. 8 is not performed, it is possible to suppress the pipe house 10 (especially the partition 11 part) from being damaged due to the pressure difference between the cultivation space S1 and the air-conditioned space S2.

[0050] Also, the control unit 30 functions as an example of a fifth control unit that controls the rotation speeds of the plurality of return duct fans 25 according to the pressure difference between the air-conditioned space S2 and the external space S4. The control unit 30 performs control using a fifth rotation speed table in which the pressure difference between the air-conditioned space S2 and the external space S4 is associated with the reference rotation speed of each return duct fan 25. The reference rotation speed and the rotation speeds of the other return duct fans 25 are the same as those described in the second rotation speed table.

[0051] Fig. 9 is a diagram showing an example of the fifth rotation speed table. In the fifth rotation speed table TB5 shown in Fig. 9, pressure differences between the air-conditioned space S2 and the external space S4, namely "-E61", "-E62", "-E63", "-E64", "+E65", "+E66", "+E67", and "+E68" (-E61>-E62>-E63>-E64>0>+E65>+E66>+E67>+E68), are associated with reference rotation speeds of the return duct fan 25, namely "RS61", "RS62", "RS63", "RS64", "RS65", "RS66", "RS67", and "RS68".

[0052] A negative pressure difference indicates that the air pressure in the air-conditioned space S2 is lower, and a positive pressure difference indicates that the air pressure in the air-conditioned space S2 is higher. In this case, the reference rotation speeds have a magnitude relationship of, for example, RS61>RS62>RS63>RS64>RS65>RS66>RS67>RS68. In this way, the control unit 30 controls the reference rotation speed to be lower as the air pressure in the air-conditioned space S2 is higher than the air pressure in the external space S4, thereby reducing the amount of air returning from the cultivation space S1 to the air-conditioned space S2.

[0053] As a result, the higher the air pressure in the air-conditioned space S2 is compared to the air pressure in the external space S4, the less air is sent into the air-conditioned space S2 to lower the air pressure in the air-conditioned space S2, and the air pressure difference between the air-conditioned space S2 and the external space S4 becomes smaller than when the reference rotation speed is uniform. With this configuration, it is possible to prevent damage to the pipe house 10 (especially the part covering the air-conditioned space S2) due to the air pressure difference between the air-conditioned space S2 and the external space S4, compared to when the control described in Fig. 9 is not performed.

[0054] The control unit 30 also functions as an example of a sixth control unit that controls the rotation speeds of the multiple return duct fans 25 in response to the air pressure difference between the growth space S1 and the external space S4. The control unit 30 performs control using a sixth rotation speed table that associates the air pressure difference between the growth space S1 and the external space S4 with the reference rotation speed of each return duct fan 25. The reference rotation speed and the other rotation speeds of the return duct fans 25 are the same as those described in the second rotation speed table.

[0055] FIG. 10 is a diagram showing an example of the sixth rotation speed table. The sixth rotation speed table TB6 shown in FIG. 10 associates the pressure differences between the cultivation space S1 and the external space S4, namely, "-E71", "-E72", "-E73", "-E74", "+E75", "+E76", "+E77", and "+E78" (-E71 > -E72 > -E73 > -E74 > 0 > +E75 > +E76 > +E77 > +E78), with the reference rotation speeds of the return duct fan 25, namely, "RS71", "RS72", "RS73", "RS74", "RS75", "RS76", "RS77", and "RS78".

[0056] It is assumed that when the pressure difference is negative, the pressure in the cultivation space S1 is lower, and when the pressure difference is positive, the pressure in the cultivation space S1 is higher. In that case, each reference rotation speed has, for example, a magnitude relationship of RS71 < RS72 < RS73 < RS74 < RS75 < RS76 < RS77 < RS78. In this way, the control unit 30 controls to increase the reference rotation speed as the pressure in the cultivation space S1 is higher compared to the pressure in the external space S4, so as to increase the air sucked up from the cultivation space S1.

[0057] Thereby, as the pressure in the cultivation space S1 is higher compared to the pressure in the external space S4, more air is sucked up from the cultivation space S1 to lower the pressure in the cultivation space S1, and the pressure difference between the cultivation space S1 and the external space S4 is made smaller compared to the case where the reference rotation speed is uniform. In such a manner, it is possible to suppress the damage of the pipe house 10 (especially the portion covering the cultivation space S1) due to the pressure difference between the cultivation space S1 and the external space S4 compared to the case where the control described in FIG. 10 is not performed.

[0058] <Configuration Variations> In the embodiment, the structure forming the growing space S1 and the air-conditioned space S2 is a pipe house 10, but is not limited to this. For example, the structure may be a steel frame house made of steel instead of pipes. Also, the growing space S1 and the air-conditioned space S2 may be formed by a building made of concrete like a so-called plant factory. In either structure, by providing a return duct 26, it becomes difficult for the changed air to stagnate, and conditioned air can be efficiently supplied to the crops.

[0059] In the embodiment, the shape of the growth space S1 is a rectangle when viewed vertically from above, but is not limited thereto. When viewed vertically from above, the shape of the growth space S1 may be an L-shape bent midway, an elongated ellipse, or an arc. In any case, when the growth space S1 has a shape with a defined longitudinal direction and lateral direction when viewed vertically from above, the return duct 26 is provided along the longitudinal direction to a position farther from the end of the growth space S1 on the air-conditioned space S2 side than the center of the growth space S1, so that the conditioned air can be circulated over a wider range of the growth space S1 than when the return duct 26 is short.

[0060] The return duct 26 may be provided only to a position closer to the end of the air-conditioned space S2 than the center of the growing space S1 along the longitudinal direction. Even in this case, the changed air is less likely to stagnate in the range where the return duct 26 is provided, and the conditioned air can be efficiently supplied to the crops. In short, the return duct 26 can obtain a certain effect just by being provided. The wider the range of the return duct 26 provided along the longitudinal direction, the more desirable it is, and the greater the range of the return duct 26 is, such as 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the longitudinal range of the growing space S1, the greater the degree of the effect of circulating the conditioned air in a wider range of the growing space S1.

[0061] In addition, in the embodiment, the air conditioning system 20 includes two supply ducts 24 and one return duct 26, but this is not limited thereto. The air conditioning system 20 may include one supply duct 24 or three or more supply ducts 24, or may include two or more return ducts 26. In short, it is sufficient for the air conditioning system 20 to include one or more supply ducts 24 and one or more return ducts 26.

[0062] In addition, in the embodiment, the return duct 26 is provided with a plurality of return duct fans 25, but only one return duct fan 25 may be provided. Even in this case, the changed air is less likely to stagnate in the vicinity of the return duct fan 25, and conditioned air can be supplied to the crops more efficiently than when the return duct fan 25 and the return duct 26 are not provided. In addition, in the embodiment, the supply duct 24 is provided with a plurality of openings 40, but only one opening 40 may be provided. Even in this case, conditioned air is supplied to the growing space S1. In short, it is sufficient that one or more return duct fans 25 and openings 40 are provided.

[0063] <Additional Notes> Furthermore, it may be provided in the following aspects:

[0064] (1) An air conditioning system comprising: an air conditioning unit that outputs conditioned air; a first ventilation duct; a second ventilation duct; and a blower provided in the second ventilation duct, wherein the first ventilation duct is provided in a cultivation space in which crops are grown at a position lower than the height of the crops; and the second ventilation duct is provided in the cultivation space at a position higher than the height of the crops; the air conditioning unit is installed in an air-conditioned space having a partition between it and the cultivation space; the air conditioning unit outputs the conditioned air into the first ventilation duct, the first ventilation duct exhausts the exhausted conditioned air into the cultivation space, the blower sends air from the cultivation space into the second ventilation duct, and the second ventilation duct exhausts the air sent in by the blower into the air-conditioned space.

[0065] According to this aspect, conditioned air can be efficiently supplied to the crops.

[0066] (2) In the air conditioning system described in (1) above, the cultivation space has a shape with a defined longitudinal direction and a transverse direction when viewed vertically from above, the air conditioned space is adjacent to one end of the cultivation space in the longitudinal direction, and the first ventilation duct and the second ventilation duct are provided along the longitudinal direction from the one end to a position farther from the one end than the center of the cultivation space.

[0067] According to this embodiment, the conditioned air can be circulated over a wider area of ​​the cultivation space.

[0068] (3) In the air conditioning system described in (2) above, the second ventilation duct is provided with a plurality of the blowers, and the air conditioning system is equipped with a first control unit that controls the rotation speeds of the plurality of the blowers in accordance with the distance from the one end.

[0069] According to this embodiment, the concentration of the conditioned air in the cultivation space can be made more uniform.

[0070] (4) A crop growing system comprising the air-conditioning system according to any one of (1) to (3) above, and a structure forming the growing space and the air-conditioned space.

[0071] According to this aspect, conditioned air can be efficiently supplied to the crops.

[0072] (5) The crop cultivation system described in (4) above, further comprising a first blower that takes in outside air into the air-conditioned space, a dimming element that is provided vertically above the crop and adjusts the amount of light passing through, an exhaust port that exhausts air in the upper space vertically above the dimming element, and a second blower that takes in outside air into the upper space, wherein the second blower and the exhaust port replace the air in the upper space, and the first ventilation duct and the second ventilation duct circulate the air in the cultivation space.

[0073] According to this aspect, air can be exchanged separately above and below the light adjusting member.

[0074] (6) In the crop cultivation system described in (5) above, the second ventilation pipe is provided with a plurality of blowers, and the crop cultivation system further includes a second control unit that controls the rotation speeds of the plurality of blowers according to the rotation speed of the first blower or the second blower.

[0075] According to this embodiment, the air pressure difference between the cultivation space and the air-conditioned space can be reduced.

[0076] (7) A crop cultivation system as described in (5) or (6) above, wherein the second ventilation pipe is provided with a plurality of fans, and the crop cultivation system further includes a third control unit that controls the rotation speeds of the plurality of fans according to the rotation speed of the second fan.

[0077] According to this embodiment, the air pressure difference between the growing space and the upper space can be reduced.

[0078] (8) The crop growing system according to any one of (5) to (7) above, further comprising a fourth control unit that controls the rotation speed of the blower according to the air pressure difference between the growing space and the air-conditioned space.

[0079] According to this embodiment, the air pressure difference between the growing space and the upper space can be reduced.

[0080] (9) The crop growing system according to any one of (5) to (8) above, further comprising a fifth control unit that controls the rotation speed of the blower according to an air pressure difference between the air-conditioned space and an external space.

[0081] According to this embodiment, the pressure difference between the air-conditioned space and the outside air can be reduced.

[0082] (10) The crop growing system according to any one of (5) to (9) above, further comprising a sixth control unit that controls the rotation speed of the blower according to an air pressure difference between the growing space and an external space.

[0083] According to this embodiment, the pressure difference between the cultivation space and the outside air can be reduced. Of course, this is not the case. Furthermore, the above-described embodiments and modifications may be combined in any desired manner.

[0084] Finally, although various embodiments of the present invention have been described, these are presented as examples and are not intended to limit the scope of the invention. The new embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their modifications are within the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0085] 1: Crop cultivation system 1a: Crop growing system 10: Pipe house 11: Partition 12: Exhaust window 20: Air conditioning system 21:Air conditioner 22: Gas cylinder 23: Blower fan 24: Supply duct 25: Return duct fan 26: Return duct 27: First intake fan 28: Second intake fan 29: Bypass duct 30: Control section 31: Differential pressure gauge 32: Dimmable screen 40: Opening

Claims

1. 1. An air conditioning system comprising: The air conditioning system includes an air conditioning unit that outputs conditioned air, a first ventilation duct, a second ventilation duct, and a blower provided in the second ventilation duct, The first ventilation pipe is provided at a position lower than the height of the crops in a growing space for growing the crops, The second ventilation pipe is provided at a position higher than the height of the crop in the growing space, the air conditioning unit is installed in an air-conditioning space having a partition between the air-conditioning unit and the cultivation space, and sends the conditioned air into the first ventilation pipe; The first ventilation pipe discharges the conditioned air into the cultivation space, The blower sends air from the cultivation space into the second ventilation pipe, The second ventilation duct discharges the air sent by the blower to the air-conditioned space. Air conditioning system.

2. 2. The air conditioning system according to claim 1, The growth space has a shape in which a longitudinal direction and a lateral direction are determined when viewed vertically from above, The air-conditioning space is adjacent to one end of the cultivation space in the longitudinal direction, The first ventilation pipe and the second ventilation pipe are provided along the longitudinal direction from the one end to a position farther from the one end than a center of the cultivation space. Air conditioning system.

3. 3. The air conditioning system according to claim 2, A plurality of the fans are provided in the second ventilation duct, a first control unit that controls the rotation speeds of the plurality of blowers in accordance with the distance from the one end; Air conditioning system.

4. An air conditioning system according to claim 1; A structure forming the growing space and the air-conditioning space; Equipped Crop growing system.

5. The crop growing system according to claim 4, A first fan that takes in outside air into the air-conditioned space; A light control member that is provided vertically above the crops and adjusts the amount of light passing through; An exhaust port for discharging air from an upper space vertically above the light control member; a second blower that takes in outside air into the upper space, The second fan and the exhaust port replace air in the upper space, The first ventilation pipe and the second ventilation pipe circulate air in the cultivation space. Crop growing system.

6. The crop growing system according to claim 5, The second ventilation duct is provided with a plurality of fans, a second control unit that controls the rotation speeds of the plurality of fans in accordance with the rotation speed of the first fan or the second fan; Crop growing system.

7. The crop growing system according to claim 5, The second ventilation duct is provided with a plurality of fans, a third control unit that controls the rotation speeds of the plurality of fans in accordance with the rotation speed of the second fan; Crop growing system.

8. The crop growing system according to claim 5, A fourth control unit is provided to control the rotation speed of the blower in accordance with the air pressure difference between the cultivation space and the air-conditioned space. Crop growing system.

9. The crop growing system according to claim 5, A fifth control unit is provided to control the rotation speed of the blower in accordance with the air pressure difference between the air-conditioned space and the outside space. Crop growing system.

10. The crop growing system according to claim 5, A sixth control unit is provided to control the rotation speed of the blower in accordance with the air pressure difference between the cultivation space and the outside space. Crop growing system.

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