JP2003009678A - Cooling method, method for growing plant, cooling apparatus, and greenhouse for plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide preferable cooling method and apparatus or the like, enabling cooling and dehumidifying of the air at a low equipment cost and a low operation cost. SOLUTION: This cooling method comprises installing a spraying nozzle 12 for cold water in an outside air-introducing cylinder 10 equipped with a blower 14 and spraying cold water not higher than dew point of the outside air into the outside air stream for feeding from the outside air-introducing cylinder 10 into a greenhouse 2 for plants.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The claimed invention relates to a cooling method, a plant growing method using the cooling method, a cooling apparatus used for carrying out such a method, and a greenhouse for plants using the cooling apparatus. It is a thing.

[0002]

2. Description of the Related Art A so-called wet cooling method is often employed in a livestock building or a greenhouse for gardening. It is a method of spraying (or spraying) water into the air and cooling the air by the heat of vaporization of the atomized water, such as the cold water flow method, the put-and-fan method, the mist-and-fan method, and the air shower method. It is subdivided. There are, of course, cooling methods using an ordinary air conditioner (refrigerator), but compared with them, wet cooling has the features of low equipment cost and operating cost and low noise.

JP-A-8-42870 discloses, as an example of such a cooling means, a cold air generator which can be used in a poultry house or the like of a poultry farm. This device is a blower that is attached to the opening of the outer wall of the building like a ventilation fan (however, unlike a ventilation fan, it introduces outside air into the room).
And a water pipe with a spray nozzle attached to the front surface thereof are integrally combined. Regarding the wet cooling method, further, there is JP-A-2000-157068.
It is also introduced in the Gazette.

[0004]

[Patent Document 1] Japanese Unexamined Patent Publication No. 8-42870
When cooling the room with the device described in the publication, although the temperature of the air can be lowered by vaporizing the water,
It will increase the humidity of the air. This is because the amount of water vapor in the air increases due to the evaporation of water, while the amount of saturated water vapor decreases as the temperature of the air decreases,
In many cases, the relative humidity reaches 100%. Higher humidity is not only uncomfortable for humans entering the room, but also tends to promote the growth of mold and bacteria and excessive water content in the soil, which has an unfavorable effect on the growth of plants and animals. .

The method described in Japanese Unexamined Patent Publication No. 2000-157068 takes this point into consideration, and the dehumidification is performed simultaneously with the cooling. That is, when the indoor humidity becomes excessive, the indoor air is sent to the dehumidifying means, where it is dehumidified and dried to return the air to the indoor. As the dehumidifying means, a gas separation membrane type gas-liquid separator such as a polymer hollow fiber membrane is used.

However, the Japanese Unexamined Patent Publication No. 2000-157068.
Regarding the method of the publication, the following points are not preferable to the user. That is, (a) the special dehumidifying means as described above is required, and the equipment cost is correspondingly high. (B) The dehumidifying means also collects dust and the like in the air by filtering it. Maintenance that requires operating costs such as periodical replacement of the gas-liquid separator, which is a means, is necessary. C) To suck the air in the room and return it to the room after passing through the above dehumidifying means with less resistance. Would require expensive air circulation equipment, including air pressurizing means (compressors, etc.) with considerable output.

The invention according to the claims is made in order to improve the above points, and it is possible to perform dehumidification (dehumidification) at the same time as cooling, and at the same time, the equipment cost and the operation cost are low. The present invention is intended to provide an air conditioner, a method for growing plants using the same, and a greenhouse for plants.

[0008]

According to the cooling method of the present invention, cold water having a temperature lower than the dew point (condensation temperature) of the outside air is sprayed into the outside airflow introduced into the room (that is, mist or water droplets). It is blown out or sprayed).

If water having a temperature above the dew point is sprayed into the outside airflow, the air (outside air) cooled by the water has an increased absolute humidity, and a slight temperature drop causes the relative humidity to rise to 10%.
It is easy to reach 0%. However, if the water to be sprayed is cold water below the dew point, the absolute humidity of the air can also be lowered,
Therefore, even if the air temperature is greatly lowered, it becomes easy to maintain the relative humidity of the air below 100%. Cooling and dehumidifying can be performed in this way because the water droplets of cold water are not easily vaporized due to the low temperature, and the water in the air is condensed near the surface of the water droplets and is taken into itself. That is, according to the present invention, cold water is sprayed into the outside airflow, and the roughness (for example, the diameter is 0.1 to 1.0) that does not vaporize immediately after spraying by devising the spraying conditions and the like.
If the total surface area is sufficiently large by scattering a large number of water droplets (around mm), the temperature of the air will drop due to contact with the water droplets, and the air will decrease due to the condensation of water on the surface of the water droplets. Wetting is also performed.

The fact that the air can be cooled and dehumidified by bringing it into contact with cold water having a temperature below the dew point can be confirmed based on FIG. 3 which is a moist air diagram and FIG. 4 which is an enlarged view near the IV portion thereof. it can. For example, in the outside air F ₀ in a state indicated by a point F ₀ (dry-bulb temperature t = 35 ° C., relative humidity φ = 60%) in the figure, the dew point temperature (26
When sprayed with water at 28 ° C, which is higher than
Since the absolute humidity x increases along with the broken line F ₀ X, the relative humidity φ becomes 100% at the point X when the temperature (dry bulb temperature) reaches about 28.5 ° C. In contrast, outside air F
_When cold water having a dew point below 20 ° C., for example, is sprayed in ₀ , the air (outside air F ₀ ) changes along the solid line F ₀ Y, so the absolute humidity x decreases. Moreover, the relative humidity φ is 100% compared to the case where it changes along the broken line F ₀ X.
The width of the temperature drop can be widened within the range that does not become. For example, even when the actual state change is up to the point F ₁ , the dry bulb temperature t drops to about 26 ° C. while the relative humidity φ remains about 80%.

The cooling method according to the first aspect is a simple wet cooling method in which cold water is sprayed into the air, and is therefore advantageous in terms of equipment cost, operating cost and noise. Further, it is a great merit of this cooling method that it is possible to perform dehumidification, but it is not necessary to use a special dehumidifying means.

In the cooling method according to the second aspect of the present invention, the outside airflow after spraying the cold water as described above is mixed with a part of the room air, and further cooled by the cooling means for the air to introduce the air into the room. It is characterized by Of course, including the case of claim 1, the same amount of air as the introduced outside air is discharged from the room. As the above-mentioned cooling means for air, for example, a cooling coil through which cold water flows can be used.

It is a very common process in air conditioning to mix the outside air with part of the room air, cool it and introduce it into the room. This cooling method is performed by combining such a general process after the cooling process by spraying cold water as described above. Based on the combination of the two processes, this cooling method has the following advantages:

1) A so-called reheat effect can be obtained by mixing the outside airflow after spraying cold water with a part of the room air. By mixing the air, which has become slightly saturated by the cold water spray, with the room air, the temperature is slightly raised, and the temperature is again increased from the saturated state. When it becomes far from the saturated state, it is easy to avoid that the relative humidity becomes 100% even in the subsequent cooling by the cooling means. Explaining in the example of FIG. 4, mixing the air F ₁ after cold water spraying indicated by the point F ₁ with the room air R indicated by the point R results in the state of the point M, and the relative humidity φ = 100% is obtained. It can be pulled away from the saturation curve shown. Even if the air is cooled from point M to point C (supply air C) by a cooling means such as a refrigerator and sent into the room, the state of point R (indoor air R) away from the saturation curve is maintained. Is.
It should be noted that the similar reheat effect may be obtained by warming the second outside air F ₁ with, for example, solar heat (thus, the operation cost is low).

2) Since two kinds of cooling processes are used in combination, it is possible to realize a preferable cooling which is highly reliable and in which the air condition such as temperature and humidity can be freely set. Cooling with high reliability can be performed because if some trouble occurs in one process, some cooling can be continued by the other process. The air condition can be set freely, in addition to adjusting the air condition using one of the two processes that can be controlled, the cooling intensity ratio by each process,
This is because the air condition can be finely adjusted by changing the mixing ratio of the outside air and the room air after the cold water spray.

3) Since the cooling process of spraying cold water is included, the cooling load applied to a general air conditioning system used in the subsequent process is naturally smaller than that when the system is used alone. Since the equipment cost required to realize the former process is low as described above, the equipment cost required for cooling in total is considerably reduced.

The cooling method according to claim 3 is
A cooling coil for flowing cold water inside is used as the cooling means for the air (in the later process) described above, and the cold water flowing in the coil and the cold water sprayed as described above are commonly provided with a cooling means for water. It is characterized by being supplied from the water tank.

According to such a cooling method, the cold water prepared in one water tank can be used for both spraying into the outside air flow and flowing into the cooling coil as described above, Effective use of cold water is achieved. Since cold water to be used for two purposes is prepared in one common water tank, there is also an advantage that equipment cost and tank installation space can be saved.

According to a fourth aspect of the present invention, there is provided a method for growing a plant, characterized in that any one of the above-mentioned cooling methods is used for cooling a plant greenhouse.

When growing high-quality plants including orchids (such as cymbidium) and cut flowers in a greenhouse, it is desirable that the air temperature is about 28 ° C. even in the summer, and the relative humidity is 100%. Since it is easy to cause root rot or get sick in a close condition, it is preferable to keep it around 60%. In addition, regarding cooling for growing plants, continuous cooling for a long time is required, and there is a feature that the cost cannot be as high as that of human living environment.

The plant growth method according to the present invention is very suitable for such characteristics relating to plant growth. Because all of the above-mentioned cooling methods perform air cooling and dehumidification by spraying cold water, etc., the equipment cost and operating cost are low, and the configuration is simple, so that continuous operation for a long time is possible. This is because it is easy to drive the vehicle automatically.

Although it is necessary to regularly give fertilizers and chemicals to plants, this growing method is also suitable in that such fertilization or drug application can be easily performed. When the above-mentioned cooling method is adopted, liquid fertilizer or chemical liquid is mixed and sprayed in cold water, and water droplets (droplets) are carried on the air flow to be introduced.
This is because if the amount of spray and the particle size of water droplets are adjusted so as to spread widely throughout the room, fertilization or drug application to all plants in the room will be completed even if humans do little work.

According to a fifth aspect of the present invention, there is provided a cooling device including: a) an outside air introducing cylinder provided with a blower for forming an outside air flow toward a room, a spray nozzle for cold water, and a receiving portion for the sprayed cold water,
b) A water tank equipped with a cooling means is attached, and c) The outlet of the water tank is connected to the spray nozzle of the outside air introducing cylinder, and the return port of the water tank is connected to the receiving portion of the introducing cylinder. It is characterized by

According to this cooling device, the cooling method described in claim 1 can be carried out smoothly. That is,
The outside air introduction cylinder of the above a) forms the outside airflow to be introduced into the room by the blower, and sprays cold water from the spray nozzle into the formed outside airflow. And the water tank of b) is
Since the cooling means is provided, the water is cooled, and cold water having a temperature below the dew point of the outside air is prepared.

Moreover, in this apparatus, most of the sprayed cold water can be collected and repeatedly used for spraying, which allows efficient circulation. As described in c) above, since the discharge port of the water tank is connected to the spray nozzle and the return port is connected to the cold water receiving part, most of the sprayed cold water is received in the receiving part and then collected in the water tank. This is because the temperature can be lowered again by the cooling means and the temperature can be supplied to the spray nozzle.

The blower, the spray nozzle and the receiving part are integrated in the outside air introducing cylinder as in the above a), and b).
Since the device is composed of a total of three device groups, the water tank of 3) and the piping for making the connection of c),
This cooling device has an advantage that it can be easily attached to and installed in a facility to be cooled, such as a greenhouse, and further maintained.

In the cooling device according to the sixth aspect, in particular, the above-mentioned spray nozzle and the blower are arranged in this order from the upstream side in the outside air introducing cylinder, and part of the indoor air is sucked in and mixed with the outside air flow. Connect the confluence pipe between the spray nozzle and blower,
A cooling coil is provided on the downstream side of the blower to allow the cold water from the water tank to flow inside.

With this cooling device, it is possible to carry out the cooling method according to claims 2 and 3. The method of claim 2 can be carried out by first connecting the confluence pipe for sucking indoor air and mixing with the outside airflow to the location downstream of the spray nozzle and upstream of the blower, so that the outside after cold water spraying is performed. This is because the airflow can be mixed with a part of the room air, and the cooling coil is arranged on the downstream side of the blower, so that the mixed air can be further cooled and introduced into the room. The reason why the method of claim 3 can also be carried out is that the cooling coil used is one that flows cold water from the water tank for preparing cold water for spraying. If such a coil is used, the cold water to be sprayed and the cold water to flow in the coil can be supplied from a common water tank, and there is an advantage that the equipment cost and the installation space of the tank can be saved.

The greenhouse for plants according to claim 7 is characterized in that the downstream end of the outside air introducing cylinder in the above-mentioned cooling device is connected to the opening of the outer wall. With such a greenhouse, it is possible to realize the breeding method according to claim 4 while enjoying the above-mentioned advantages with respect to the cooling device.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the invention are introduced in FIGS. FIG. 1 is a system diagram when the cooling device 1 is used in a greenhouse 2 for plants, and FIG. 2 is a block diagram showing an air flow and the like in the case of FIG. 3 is a moist air diagram showing changes in the state of the air in the case of FIG. 1, and FIG.
FIG. 4 is a detailed diagram near the IV section in FIG.

The greenhouse 2 shown in FIG. 1 is for cultivating high-quality flowers for orchids and cut flowers such as cymbidium, and the cooling device 1 is the temperature of the outside air (which means the dry-bulb temperature. The same applies hereinafter). Is used to keep the room temperature at 28 ° C and 60% even in the summer when the humidity is 35 ° C and the humidity (relative humidity; the same applies below) reaches about 60%. This cooling device 1 is configured by combining an outside air introducing cylinder 10 connected to an opening portion of an outer wall of a greenhouse 2, a water tank 20 installed on the ground outside the room, and a piping system 30 connecting them.

The outside air introducing cylinder 10 of the cooling device 1 is provided with a spray nozzle 12 in a duct having openings inside and outside the room.
The water supply pipe 12a having a plurality of the above, the blower 14 and the cooling coil 15 are arranged side by side in this order from the outdoor-facing opening. The blower 14 blows air from the outside (that is, the side where the spray nozzle 12 is located) to the inside (the cooling coil 15).
The side is set) so that the direction is set to face. The direction of the spray nozzle 12 in the water supply pipe 12a is determined so that the water is sprayed toward the outside of the room, and the movement of heat is activated by the contact of the outside air flow and the spray water by the blower 14 with each other. . A water receiving portion 13 is formed at a lower front portion of the spray nozzle 12 so that the sprayed water falling can be collected.

One end of a merging pipe 16 is connected between the spray nozzle 12 and the blower 14 in the outside air introducing cylinder 10, and the other end of the merging pipe 16 is opened above the greenhouse 2. As shown in FIG. 2, the outside air introduction tube 10 sucks the outside air _{F 0} of the amount of _{G FC, G} through merging pipe 16 _R
That is, (a part of) the room air R is combined with it. The air C in the amount of total G _C of mixture was allowed to merge,
The outside air introducing cylinder 10 is sent into the greenhouse 2. The indoor air R of the same G _FC amount as the introduced outside air is discharged from the ventilation fan 3 on the outer wall of the greenhouse 2 on the side away from the outside air introduction cylinder 10.

The water tank 20 shown in FIG. 1, which is an element of the cooling device 1, produces cold water to be supplied to the spray nozzle 12 and the cooling coil 15 in the outside air introducing cylinder 10. And a cooling means 25 for cooling. The cooling means 25 includes a compressor 26, a condenser 27, an expansion valve 28, and a coil 29 which is an evaporator.
This is a refrigerator type in which a refrigerant such as CFC and ammonia is circulated in the inside, and the cooling action of the coil 15 cools the water in the tank body 21 to a minimum temperature of about 5 ° C. The tank body 21 is provided with an automatic water supply means (not shown) including a float valve so that the water amount can be kept constant, and
Cold water discharge port 22 is formed in the lower part, and return port 23 is formed in the upper part.
24 are provided.

The piping system 30 is configured to connect the water tank 20 and the spray nozzle 12, and the water tank 20 and the cooling coil 15, respectively. That is, the tank body 21
First, connect the water supply pipe 31 to the discharge port 22 at the lower part of the water supply pipe, branch it into the water supply pipes 34 and 35 of the two systems, and arrange the water supply pumps 32 and 33 and valves in each, and The tip is connected to the above water supply pipe 12a (spray nozzle 12), and the other water supply pipe 35 is connected to the cooling coil 15. A return pipe 36 is connected to the receiving portion 13 below the spray nozzle 12 so that most of the sprayed water is returned from the return port 23 to the water tank 20, and another return pipe 37 is provided at one end of the cooling coil 15. The water after passing through the coil 15 is returned to the water tank 20 through the return port 24. In addition, in the block diagram of FIG. 2, the spray nozzle 12 and the cooling coil 1 are shown together with the air flow (described above) related to the greenhouse 2.
The cold water flow for 5 and 5 is also shown.

When the cooling device 1 as described above is used, the outside air temperature (dry bulb temperature) and humidity (relative humidity) are 35 ° C. · 6.
Even in the summer when it reaches about 0%, the air in the greenhouse 2 can be kept at about 28 ° C. and 60% through the state changes shown in FIGS. 3 and 4. That is, first, the outside air introducing cylinder 10 (see FIG.
・ In Fig. 2), outside air F ₀ (35 ℃ ・ 60) to be introduced
%, Enthalpy i is i = 22.0 kcal / kg) by spraying cold water (lower than the dew point temperature of the outside air F ₀ , for example, 20 ° C.) from the spray nozzle 12 to bring air into contact with the cold water. The state of the second outside air F ₁ in FIG. 4 (about 26 ° C., 80%, i = 17.0 kcal / kg)
Cool down to dehumidify. Subsequently, a part of the air R in the greenhouse 2 coming from the confluence pipe 16 is transferred to the second outside air F ₁ in the outside air introducing cylinder 10.
As a result of being mixed with the second introduction air F ₁ , the mixture M having a temperature slightly higher than the second outside air F ₁ but a low humidity is mixed in the introduction cylinder 10.
(About 27 ° C./70%, i = 16.5 kcal / kg) is obtained. The air-fuel mixture M is heat-exchanged with, for example, the cooling coil 15 in which cold water of 14 ° C. is passed, so that the temperature of the supply air C (about 18 ° C./90%,
i = 11.6 kcal / kg) and blown into the greenhouse 2. The supply air C mixes with a large amount of other air in the greenhouse 2 and, as a result, about 28 ° C. and 60%, i = 15.8.
The indoor air R is kcal / kg.

An example of heat load and equipment specifications when the greenhouse 2 is a glass greenhouse having an area of about 20 tsubos is introduced below.

Firstly, considered the the greenhouse 2, there is heat increased Q _o in total by generated heat of the heat Q _r inside with the heat Q _c from the outside as shown in FIG. 2 enters. Q
_{Although r} ≈ 0, Q _c is estimated to be approximately Q _c = 6350 kcal / h based on the area and gap between the wall and floor of the greenhouse 2 and the temperature difference between the inside and outside of the greenhouse, and therefore Q _o is also about It is assumed to be 6350 kcal / h. This is the heat load on the greenhouse 2.

Then, a part of the heat quantity Q ₁ of such heat load Q _o is removed in the first stage cooling in which cold water is sprayed in the outside air introducing cylinder 10. That is, as shown in FIG. 2, the amount of external air sucked into the introduction cylinder 10 (equal to the amount of air discharged from the room) G _FC is 400 kg /
outside air F ₀ (35 ° C ・ 60%, i = 22.0k)
cal / kg) and the second outside air F ₁ (about 26 ° C./80%, i
= 17.0 kcal / kg), the heat quantity Q ₁ is about 200.
It can be calculated as 0 kcal / h. Approximately one third of the total heat load Q _o, it is deprive from the air by the cooling of the first stage of cold water spray. For that purpose, the spray amount of cold water is determined so as to come into contact with a sufficient amount of air in consideration of the heat of condensation of water in the air (550 kcal / kg). In this example, the spray amount is about 20 kg / h, and the equipment is 5-100 kg.
Be prepared to adjust the amount within the range of / h.

Remaining heat quantity Q ₂ in the heat load Q _o (= Q _o −
Q ₁ = 4350 kcal / h) means that the second outside air F ₁ cooled in the first stage is mixed with a part of the indoor air R of the greenhouse 2 to form a mixture M and then further cooled by the cooling coil 15. Remove by two stages of cooling. Mixing the amount _{G R} of the room air R and 490 kg / h, is introduced 400kg
/ G of external air flow rate G _FC and a total air-fuel mixture M of 890 kg / h
(About 27 ° C./70%, i = 16.5 kcal / kg) supply air C (about 18 ° C./90%) by the cooling coil 15.
%, I = 11.6 kcal / kg), the heat quantity Q ₂ (= 890 × (16.5−5)
11.6) = 4350 kcal / h) can be removed from the air.

If the inside of the greenhouse 2 is cooled as described above, the cooling capacity of an ordinary air conditioner used as the cooling coil 15 is about 4350 kcal / h, which is conventionally required for a glass greenhouse of about 20 tsubo. A large air conditioner (cooling capacity of more than 6000 kcal / h) is not required. The heat quantity that the cooling capacity of the air conditioner used does not reach is removed by the simple and low-cost means of spraying cold water into the introduced air.
The cost required for air conditioning can be greatly reduced.
In addition, about equipment other than the cooling coil 15 in the above example of a 20-tsubo greenhouse, the blower 14 has 0.2 kW, the compressor 26 of the water tank 20 has 2.2 kW, and the condenser 27.
Output of 6.2 kw, and the ventilation fan 3 of the greenhouse 2 needs output of 0.1 kw. The tank body 21 has 120
It is desirable to have a capacity of about 0 liter. However, it goes without saying that if the size of the greenhouse 2 changes, the required output and required capacity will also change.

[0042]

According to the cooling method described in claim 1,
The outside airflow introduced into the room can be cooled and dehumidified, so that the room can be cooled and dehumidified. Moreover, this method is a simple cooling method in which cold water is sprayed into the air, and dehumidification can be performed without using a special dehumidifying means, which brings about a great advantage that the equipment cost and the operating cost are low.

Since the cooling method according to the second aspect combines the general cooling process after the cooling process by spraying cold water, 1) it is difficult for the relative humidity to approach 100%, and 2) the reliability is high. Moreover, there are advantages that the air condition such as temperature and humidity can be set freely, and 3) the total equipment cost required for cooling is greatly reduced.

In the cooling method according to claim 3, in particular,
The cold water prepared in one water tank can be effectively used, and the equipment cost and installation space for the water tank can be saved.

According to the method for growing plants described in claim 4, various aspects such as keeping the inside of the greenhouse at a low humidity, being capable of continuous operation for a long time, and being required to have a low cost-- Thus, high-quality plants such as orchids can be properly raised. It also makes it easier to apply fertilizers or drugs to plants on a regular basis.

According to a fifth aspect of the present invention, there is provided the cooling device according to the first aspect.
The cooling method described in 1 above can be carried out smoothly, and the above effects can be obtained. It is also advantageous that the cold water to be sprayed can be circulated without waste and can be used repeatedly, and that it can be easily installed in a greenhouse or the like and maintained.

According to the cooling device of the sixth aspect, the cooling method of the second and third aspects can be carried out, and the above effects can be obtained.

According to the seventh aspect of the greenhouse for plants, in addition to the merits relating to the air conditioner, the above-mentioned effects can be brought about by the fact that the growing method according to the fourth aspect can be carried out.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the invention, and is a system diagram when the cooling device 1 is used in a greenhouse 2 for plants.

FIG. 2 is a block diagram showing the flow of air and the like in the case of FIG.

FIG. 3 is a moist air diagram showing changes in the state of the air in the case of FIG.

FIG. 4 is a detailed view near a portion IV in the moist air diagram of FIG.

[Explanation of symbols]

1 Air conditioner 2 Greenhouse for plants 10 Outside air introduction tube 12 spray nozzles 13 Receiver 14 blower 15 Cooling coil (cooling means for air) 16 confluence pipe 20 water tank 22 Discharge port 23.24 Return port 25 Cooling means (for water) 30 piping system

Claims (7)

[Claims] 1. A cooling method, characterized in that cold water having a temperature lower than the dew point of the outside air is sprayed into the outside airflow introduced into the room. 2. The cooling method according to claim 1, wherein the outside airflow after the cold water spray is mixed with a part of the indoor air and further cooled by the cooling means for the air to be introduced into the room. . 3. A cooling coil for flowing cold water therein is used as the cooling means for the air, and the cold water flowing in the coil and the cold water sprayed as described above are provided in common with a cooling means for water. It supplies from a water tank, The cooling method of Claim 2 characterized by the above-mentioned. 4. A method for growing plants, which comprises using the cooling method according to claim 1 for cooling a plant greenhouse. 5. An outside air introduction cylinder provided with a blower for forming an outside air flow toward the room, a spray nozzle for cold water, and a receiving portion for the sprayed cold water, and a water tank provided with cooling means are attached to the outside air introduction cylinder. The cooling device is characterized in that a discharge port of a water tank is connected to the spray nozzle of, and a return port of the water tank is connected to a receiving portion of the outside air introducing cylinder. 6. The outside air introducing cylinder is provided with the above-mentioned spray nozzle and blower in this order from the upstream side, and a merging pipe for sucking a part of indoor air and mixing with the outside air flow is a spray nozzle / blower. The cooling device according to claim 5, further comprising a cooling coil which is connected between the cooling fan and the cooling water flowing from the water tank to the inside of the cooling coil. 7. A greenhouse for plants characterized in that the downstream end of the outside air introducing cylinder in the cooling device according to claim 5 or 6 is connected to the opening of the outer wall.