JPS5922143B2 - Greenhouse air conditioning methods and equipment - Google Patents

Description

[Detailed Description of the Invention] Greenhouses used for growing tropical plants or forced cultivation of vegetables, flowers, etc.9 are usually operated by burning fuel to warm the air inside the greenhouse in cold weather.

For example, during the winter on a sunny day, the temperature inside the greenhouse rises sufficiently or more than necessary due to the heat from the sun's rays passing through the roof and side walls made of transparent materials. The temperature is maintained at the appropriate temperature simply by adjusting the entrance and exit, but at night or on cloudy or rainy days, the temperature is maintained by burning fuel and directly or indirectly warming the air inside the greenhouse.

Therefore, fuel costs account for a very large portion of the costs of operating a greenhouse.

Furthermore, when the temperature inside the greenhouse rises due to the heat from the sun's rays during the afternoon on a clear day in winter, around 60% of the sun's energy is used to heat the air, but the remaining 40% comes from the soil surface and the leaves of the plants. is spent on latent heat for the evaporation of water from the surface.

Therefore, since moisture evaporates actively, the humidity in the greenhouse often exceeds 9°C, which often causes diseases and adversely affects the growth of 9-pointed plants.

The present invention installs an air conditioner using a heat pump in a greenhouse, and when the temperature and humidity inside the greenhouse rise due to solar heat during the daytime on a sunny day in winter, the dehumidifier of the air conditioner dehumidifies the air to keep the humidity low. In order to prevent the temperature from rising more than necessary due to condensation heat and solar heat, the sensible heat that is removed is used to raise the water temperature in a separately equipped aquarium, storing heat, and releasing the heat stored in that aquarium at night when there is no solar heat. This method maintains the air in the greenhouse at an appropriate temperature, and the benefits obtained by this method are as follows.

■) Part of the solar heat during clear daylight in winter is stored in a water tank and released during cold nights to keep the greenhouse at an appropriate temperature, so it requires significantly less fuel than heating the greenhouse by burning fuel.

When it's cloudy or rainy, it's unavoidable to use fuel, but when it's sunny, you can do without fuel, as I'll explain in detail later.

2) Since the humidity in the greenhouse is kept at a suitable level, the incidence of diseases is extremely low.

3) By keeping the temperature in the greenhouse low, the evaporation of water from the leaf surfaces of plants and the uptake of water from the roots become active, which in turn increases the uptake of nutrients. is promoted.

4) If the humidity inside the greenhouse is high during clear skies in winter, condensation will form on the inner surfaces of the roof and walls.

This condensation indicates that the latent heat of the water vapor is carried away to the outside air, which means that the heat loss is large (the energy that has been obtained through the effort is wasted).

In the present invention, since the humidity is kept low (no dew condensation occurs), there is little heat loss (that is, solar heat can be utilized to a high degree).

The present invention will be described in detail with reference to embodiments as follows.

In Figure 1, 1 is a greenhouse whose roof and outer walls are made of transparent material to allow sunlight to pass through.

2 is the soil in which the plants are planted, and 3 represents the plants.

4 represents an air conditioner set, which can be installed inside or outside the greenhouse.

This can be done by installing each piece of equipment individually and connecting them with pipes and ducts, or by installing a unit type in which each piece of equipment is functionally combined and installed in one case, but as shown in Figure 1. Here, it is surrounded by a dotted line to indicate set 1.

5 indicates an air duct, which is simply represented by a single line in a flow sheet format.

This duct can be run inside the greenhouse, but in Figure 1 it is shown running outside the greenhouse to avoid dust.

6 is an evaporator (air cooler), 7 is a compressor, and 8 is a condenser (
(air heater), 9 is an expansion valve, and these four complete the refrigerant cycle of the heat pump.

The condenser (air heater) 8 is composed of two conduit lines 10 and 11 which are alternately arranged and pass through a common group of fins.

A refrigerant passes through the first pipe line 10, and the refrigerant radiates heat here and liquefies it.

Water from a water tank 13 is circulated through the second pipe line 11 by a pump 12 .

14 is a ventilator. The air from the greenhouse coming through duct 5 is sent to evaporator 6. The air passes through the condenser 8 and enters the suction side of the ventilator 14, and since the discharge side of the ventilator 14 is open into the greenhouse, the air in the greenhouse passes through the air conditioner 4 and circulates as shown by the arrow. .

Based on the apparatus of this embodiment, the following formula will be explained using a specific example of the number 1 rotation.

In the Omote Japan area, there are many sunny days in the winter (the amount of solar radiation transmitted through the greenhouse during the day is 1,700 kc relative to the flat area).
It can be considered as a7/m2 ・day.

Assuming that the planar area of the greenhouse is 100 m2 and the sunshine duration is 8 hours, the amount of heat received per hour is 1700 kcu/m2 - day x 100 m2 ÷ 8 o'clock field/day = 21000 kca17' hour.

If the temperature inside the greenhouse during the day is 23℃ and the outside temperature is 10℃, the amount of heat lost to the outside through the roof and outer walls (assuming a total area of 200m2) is (based on experience, the heat transfer coefficient is approximately 4
．． 8kcal/rIL2・hour-'c) 4.8 k
c al/m2・hour・℃×200rrL2×(23-
10) T, = 12500 kcat/R.

In other words, approximately 60% of the incident heat is lost through the roof and exterior walls, and the remaining 4.
0% becomes latent heat and evaporates water.

This balances heat input and heat output and maintains the indoor temperature at 23°C.

The amount of evaporated water is (21000 kcat/hour - 12500
kca,/.

7 o'clock) ÷ 580 kc a, /, / to 9 = 14.7 to 9
It's 7 o'clock.

The air entering the evaporator (air cooler) 6 through the duct 5 is the same as the ambient air inside the greenhouse 1 and is kept at a temperature of 23°C.
2Estimate the humidity to be 80%.

The evaporator 6 is constructed of a finned tube and is of a type that directly cools air by evaporating a refrigerant.

As the air passes through it, it is cooled and moisture condenses on the fins to dehumidify it.

Water generated by dehumidification flows and collects on a saucer 15 and is discharged to the outside through a pipe 16.

(In Figure 1, the fins of the evaporator 6 are drawn horizontally, but this is because the fins are drawn vertically (and the route of the refrigerant pipes is difficult to understand, so I had to draw them horizontally. In reality, the fins are placed vertically so that condensed water can flow easily.

) By setting the air flow rate circulated by the ventilation fan 14 to 60rrL3/min and designing the evaporator 6 appropriately, the air that came in at a temperature of 23°C and a humidity of 80% is cooled and dehumidified, and the air is cooled and dehumidified to a temperature of 16°C and a humidity of 95%.
%.

Calculating the water removed at this time is as follows.

The absolute humidity of air at a temperature of 23°C and humidity of 80% is 0.014
1 kg/kg air, temperature 16°C2 The absolute humidity of air at 95% temperature is o, o lo Since it is 7 kg/kg air, the difference in absolute humidity is 0.0141-0.0107 = 0.0034 kg/k
With g air, the amount of recirculated air is 60 = 7 minutes, so the amount of dehumidification per hour is 0.0034 kg/kg air x 6 air rL3/min x 1
．． 2kg/rIL3 x 60 minutes = 14.7 to 9/hour.

In other words, the amount of water evaporated by sunlight incident calculated earlier and 〒
Therefore, all of the evaporated water in the greenhouse is removed by the evaporator 6, and therefore the humidity in the greenhouse is maintained at 80%.

The cooled and dehumidified air passes through the evaporator 6 and continues to the condenser (
air humidifier) 8.

The condenser 8 is of the special construction previously mentioned.

That is, a first pipe line 10 through which the refrigerant radiates heat and is liquefied, and a second pipe line 11 through which water from a water tank 13 circulates through the pump 12 are arranged alternately through a common fin group. .

A detailed perspective view is shown in FIG. In FIG. 2, reference numeral 17 indicates a fin group, and metal plates are arranged at intervals of several m'ttt to more than ten as shown in the figure.

Pipes 18, 19, 20, 21°2 pass through the fin group.
2.23 are arranged.

Pipe 18 is connected at the top to pipe 19, which in turn is connected to pipe 20 at the bottom.
The tube 20 is connected to the tube 21 at the top.

A tube 22 is placed between the tubes 18 and 21, and a tube 23 is placed between the tubes 19 and 20, and the tubes 22 and 23 are connected at the upper portion.

The refrigerant enters from the inlet of pipe 18, passes through pipes 19, 20, 21, and exits from the outlet of pipe 21.

Also, water enters through the tube 23 and exits through the outlet of the tube 22.

Figure 2 is drawn with the number of tubes minimized to make it easier to understand, but in reality, a large number of tubes are arranged in front or in front of the soot, and there is also a row of refrigerant tubes on the right or left of the soot. It is made by arranging a large number of rows of water pipes alternately and connecting them as shown in Figure 2.

Also, the number of fins is arranged appropriately depending on the heat load.

Air passes between the fins as shown by arrow 24.

The operation of the condenser (air heater) 80 will be explained as follows.

The refrigerant pipe group 18, 19, 20, 21 in FIG. 2 is represented by the first pipe 10 in FIG. 1, and the water pipe group 22, 23 in FIG. Ru.

FIG. 1 will be explained below.

Assume now that the condenser 8 in FIG. 1 is an ordinary condenser (air heater) having only a refrigerant pipe 10 and no water pipe 11.

The air that has passed through the evaporator 6 and has reached a temperature of 16° C. and a humidity of 95% is heated by passing through this condenser (air heater).

Calculate and check the temperature of the air at the outlet of the condenser.

The amount of heat transferred from the air to the refrigerant in the evaporator 6 is as follows.

From the humidity psychrometric diagram, at 23°C, the enthalpy at 80% is 0.
4.1 kcal/kg, 16℃, 95% enthalpy is 10.3 Kca17kg Therefore, the amount of heat obtained by the refrigerant is (14,1-10,3)kca77/kgX60r
rL3/min x 1.2ky/77L3 x 60 min = 164
00 kcal/hour Compressor 7 to transfer this amount of heat
The power is (Assuming the displacement of 9 per horsepower is 3000kcat/hour) 16.400Kca4/hour ÷ 3,000Kca4/hour・
Horsepower = 5.5 horses Crab 4.1 K, W.

Therefore, the amount of heat transferred from the refrigerant to the air in the condenser is 16.400
kca, /, / hour +860 kca t/ -WH
In X4.1, -W- = 19,900kca, /, /hour Therefore, the air that was 16℃ at the condenser inlet becomes G at the outlet, 19.900kca, /7 hours ÷ (0,24kc at/
kg ・℃×60m3/min×1.2 to 9/m3×60
) = 19℃ The temperature rises to 16 + 19 = 35℃.

With this, the temperature cannot be too high, so keep it at a suitable temperature, i.e. 23°C.
It is necessary to install an air cooler using water next to the condenser in order to maintain the same level.

That is, if an air cooler is arranged in this way and the water from the water tank 13 is circulated through the water pipes by the pump 12, the heat taken by the air cooler is used to raise the temperature of the water in the water tank 13 and store heat. You can reach your goal.

However, if you do that, the air will be overheated in the condenser and then cooled down to an appropriate temperature in the air cooler, making the heat exchanger large and uneconomical, so it is better to equip it with the above type of condenser 8. .

The function of the condenser 8 will be explained as follows with reference to FIG.

The refrigerant gas compressed in the refrigerant pipe 18 passes through and heat is transferred to the sifter 17.

Assume that the temperature of the refrigerant passing through the pipe 18 is 50°C.

On the other hand, water is passed through the water pipe 22 to cool the syringe 17.

Assume that the temperature of the water passing through the water pipe 22 is 26°C.

Since the fins 17 are made of metal with good thermal conductivity, they receive heat from the tube 18 and quickly transfer the heat to the tube 22, but the fins 17
The temperature is approximately midway between the temperature of the tube 18 of 50°C and the temperature of the tube 22 of 26°C, that is, approximately (50+26)÷2-38°C.

If the temperature of the air passing through the gap between the fins 17 is 21'C, heat will be given to the air by a temperature difference of 38-21=17C.

A part of the heat radiated from the refrigerant pipes 18, 19, 20, 21 can be given to the air and the rest can be sent to the water pipes 22, 23, but in order to adjust the ratio, the amount of water passing through the water pipes 22, 23 must be Just adjust it.

If the amount of water passing through the water pipes 22 and 23 is reduced, the water temperature will rise, and therefore the temperature of the fins 17 will be high (and the amount of heat given to the air will be large).

Because the amount of water is decreasing, the water temperature increases, but the amount of heat received by the water as a whole decreases.

If you want to give less heat to the air (and receive more heat from water), you can conversely increase the amount of water.

In this way, in FIG. 1, the air leaving the condenser 8 has a temperature of 2.
When the temperature reaches 3°C (it can be seen from the psychrometric diagram that the humidity is 61%), the air is sent into the greenhouse 1 by the ventilator 14, and the temperature inside the greenhouse 1 is maintained at 23°C.

Moreover, the humidity inside the greenhouse 1 becomes 80% due to the addition of moisture due to evaporation.

The water pumped up from the water tank 13 by the pump 12 is sent to the condenser 8.
It passes through the water tank 11 inside and is heated and returns to the water tank 13.

Therefore, the temperature of the water in the water tank 13 gradually increases.

The amount of heat stored in the water tank 13 is calculated as follows based on the numbers in the above embodiment.

The amount of heat transferred to the water in order to suppress the air temperature, which should be 35℃ in condenser 8, to 23℃ is (35-23) 'CX O, 24kca, ff7kg
・'CX 60 m”/minX 1.2kg/rrt3X
60 minutes = 12400kca, /.

7 o'clock water tank 80 dimensions width 2.2m x length 2.2m x height 2.2
m, and the amount of water stored is 90% of the internal volume, or 9600 t.

Although the aquarium is sufficiently insulated from the outside, heat loss cannot be avoided.

The average water temperature is 25℃. If the average outside temperature is 3℃ and the thermal conductivity of the insulation material is 1.0 kca7/m2 ・℃・hour, the outer surface area of the tank is 2.2rrLX2.2mX 6 = 29
rn2, so the heat loss is 1.0 kcat/rn”
・℃・hour×29rrL2×(25-3) 'CC50
40 kcal/l/hour If the heat input time of the aquarium 8, that is, the sunshine duration is 8 hours, the amount of heat storage in the aquarium that can be used is 12,400 kcal/hour x 8 o'clock - 640 kcal/hour x 24 o'clock, 83,800 kcat/day. Become.

And the water temperature rise is 83800kcat ÷ 9600 kcal/'C=8
．． The temperature will be between 7°C and 9°C.

For example, water temperature that drops to 20 degrees Celsius before sunrise will drop to 20 + 9 = 29 degrees Celsius in the evening after the sunshine ends.

Stop the heat pump when the sun goes down.

That is, the operation of the compressor 7 is stopped, and the pump 12 and the ventilation fan 14 are stopped.
Also stop.

When the temperature in the greenhouse 1 drops to 10°C or less at night, the pump 12 and the ventilation fan 14 are operated.

Then, hot water from the water tank 13 passes through the water pipe 11, and the condenser 8 acts as an air heater using the hot water, raising the temperature of the greenhouse 1.

In the device described above, in which a water-based air cooler is installed separately next to the condenser (air heater) to achieve the intended purpose, the water-based air cooler is used for night heating. It is sufficient to use the air heater as it is and circulate the hot water in the water tank 13 with the pump 12.

Based on the above embodiment, the amount of heat required for heating at night during winter is calculated as follows.

The outside temperature at night is 0°C, and the air temperature inside greenhouse 1 is 10'C.
If Vc is maintained, the roof/outer wall (as mentioned above, the total area is 20
The amount of heat lost through the curtain (assumed to be 0 m2) is (based on experience, when one layer of curtain is installed in the bathtub, the heat transfer coefficient is approximately 3.0 kcat/rrL2 ・℃・hour) 3
．． 0kcat/rrL2・℃・hour×200m2×(10
-0)'C=6000k cat/hour If this amount of heat is supplied, the temperature inside the greenhouse 1 can be maintained at 10°C.

If the heating time is 12 hours, the total amount of heat required is 6000kca77 hours x 12 hours = 72000kca7/
The amount of heat stored in water tank 8 calculated earlier is 83,800k.
c a Since it is 11 days, this amount of heat storage alone is enough to cover the entire time.

In other words, as long as the weather is clear, there is no need to burn fuel (Greenhouse 1)
This means that it can be kept at an appropriate temperature.

It is unavoidable to use fuel during cloudy and rainy days, but in Japan there are only a few such days, so by equipping the device according to the present invention, a large amount of fuel can be saved in greenhouse cultivation, and the humidity inside the greenhouse can be maintained at an appropriate level. By keeping the temperature low, diseases can be prevented and plant growth can be promoted, making a great contribution to this world.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic diagram explaining the present invention in detail, and FIG. 2 is a detailed perspective view explaining a structural example of the heat exchanger shown at 8 in FIG. 1. be.

Claims (1)

[Scope of Claims] 1. A greenhouse is equipped with an air conditioner using a heat pump and a water tank whose purpose is to store heat by increasing the water temperature, so that the temperature and humidity inside the greenhouse can be adjusted by the daytime solar heat of the winter clear sky. In order to prevent the temperature from rising above the above level, the air conditioner is operated, and the amount of heat removed for air conditioning is stored by raising the water temperature in the water tank, and the heat stored in the water tank is transferred into the greenhouse during cold nights. A method of operating a greenhouse characterized by radiating heat and maintaining the temperature at an appropriate temperature. 2. Install an air conditioner using a heat pump in the greenhouse so that the air inside the greenhouse is circulated through the air conditioner using a ventilator, and the air in the greenhouse during the day when the weather is sunny in winter is transferred to the heat pump's evaporator (air cooler). The water is then cooled and dehumidified through the heat pump condenser (air heater) and the water cooler, where it is heated to a temperature suitable for the greenhouse and returned to the greenhouse. The water inside the aquarium is circulated by a pump and removed for air conditioning.The excess heat is stored by raising the temperature of the water in the aquarium, and during cold nights, the hot water in the aquarium is pumped to cool the water in the water/air heat exchanger. The greenhouse is characterized in that the air inside the greenhouse is circulated through the sides of the heat exchanger, and the air inside the greenhouse is circulated through the air side of the heat exchanger using a ventilation fan to receive heat from the hot water and maintain the temperature of the greenhouse at an appropriate temperature. Air conditioner. 3 The heat pump condenser (air heater) and the water cooler are constructed by having two pipes that pass through a common group of fins arranged alternately, and the first pipe passes a refrigerant and the second pipe passes through a common fin group.
Claim 2, characterized in that a refrigerant condensing heat exchanger is used in which water is passed through the conduit and part of the heat generated by condensing the refrigerant is transferred to the air and the remainder is transferred to the water. Greenhouse air conditioner as described in section.