JPH0249684B2 - - Google Patents

Description

[Detailed Description of the Invention] Greenhouses used for growing tropical plants, forced cultivation of vegetables, flowers, etc. are usually operated by burning fuel to warm the air inside the greenhouse in cold weather. . On the other hand, due to the recent energy saving trend, when the temperature and humidity of a greenhouse rises due to solar heat during the day, a heat pump absorbs the excess heat and stores it as hot water in the aquarium, which can be used for heating during cold nights. A method to do this has been developed (see Japanese Patent Publication No. 59-22143).

The present invention installs an air conditioner using an aquarium and a heat pump in a greenhouse, heats the greenhouse by pumping up the retained heat of the water in the aquarium with the heat pump at night, lowers the water temperature in the aquarium, and then heats the greenhouse during the day. When the temperature and humidity in the greenhouse rise due to this, the excess rise in temperature and humidity is absorbed by the cold water in the aquarium and stored as heat, which is then pumped up by the heat pump at night and used as a heat source to warm the greenhouse.

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

In the attached diagram, 1 is a greenhouse, and the roof and outer walls are made of transparent material to allow sunlight to pass through. 2 is a ventilator, which causes the air in the greenhouse 1 to pass through the heat exchangers 3 and 4 and move as shown by the arrows 5, 6, and 7.
It cycles like this. 8 is a refrigerant compressor, 9 is a refrigerant evaporator (heat exchanger 3 is a refrigerant condenser), 10 is an expansion valve, and the refrigerant is connected to arrows 11 and 12.
The heat pump cycle is completed as follows. In the heat exchanger 3, the circulating air is warmed by the condensation of the refrigerant, while in the evaporator 9, the evaporation of the refrigerant removes heat from the water passing through its tubes. 13 is a water tank, and the water is supplied by a pump 14 through a valve 17 and a water pipe in the evaporator 9 in the direction of arrows 15, 16, 18.
It circulates like this. Now close valve 17 and close the other valve 1.
When 9 is opened, water does not pass as shown by arrow 16, but passes through the water pipes of heat exchanger 4 as shown by arrows 20 and 21. In the heat exchanger 4, air passing as shown by arrows 5 and 6 and water passing as shown by arrows 20 and 21 exchange heat.

Based on the apparatus of this embodiment, an explanation will be given below using an example of specific numerical values.

Let's take as an example a sunny day in late January in the Omote Japan area. Based on experience, the amount of solar radiation transmitted through the greenhouse during the day can be estimated to be 1700 Kcal/m ² ·day based on the flat area.
Assuming that the greenhouse area is 100m ² and the sunshine hours are 8 hours, the average amount of heat received per hour is 1700Kcal/m ² day x 100m ² ÷ 8 hours =
21000Kcal/hour. 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 (total area of 200m ² ) is approximately 4.8Kcal/m ² based on experience.
4.8Kcal/ ^m2・hour・℃× ^200m2 ×(23−10)℃=12480Kcal/hour. In other words, approximately 70% of the incident heat is lost through the roof and exterior walls, and the remaining 30% becomes latent heat that evaporates moisture. This balances out human heat and fever, keeping the indoor temperature at 23°C. The amount of evaporated water is (21000−12480)Kcal/hour ÷ 580Kcal/Kg = 14.7Kg/hour.

During the day, the air inside the greenhouse will be kept at a temperature of 23°C and humidity at 85%. When the ventilation fan 2 is operated, arrow 5,
6 and 7, the air entering the water/air heat exchanger 4 has the same temperature and humidity as the air inside the greenhouse. On the other hand, assume that the water temperature in the water tank 13 reaches 2° C. in the morning before sunrise. Then, when the temperature inside the greenhouse reaches 23° C. due to sunlight, the pump 14 is operated, the valve 19 is opened and the valve 17 is closed, and the water circulates according to the arrows 15, 20, 21, and 18. The heat exchanger 4 is composed of a water tube with fins, and the air passing along the arrows 5 and 6 is cooled by cold water passing through the water tube. Moisture in the air condenses on the fins and is dehumidified. The water generated by dehumidification flows down, is received by the tray 22, and is discharged to the outside through the discharge pipe 23. The air volume circulated by the ventilation fan 2 was set to 60 m ³ /min, and the heat exchanger 4 was appropriately designed to maintain a temperature of 23°C and humidity.
The incoming air is cooled and dehumidified at 85% and the temperature
It can be set to 16.5℃ and humidity of 98%. The amount of water removed at this time is calculated as follows. The absolute humidity of air with a temperature of 23℃ and humidity of 85% is
The absolute humidity of 0.0150Kg/Kg air, temperature 16.5℃, and 98% humidity is 0.0116Kg/Kg air, so the difference in absolute humidity is 0.0150−0.0116=0.0034Kg/Kg air, and the amount of circulating air is 60m ³ /min, so the amount of dehumidification per hour is 0.0034Kg/Kg air x 60m ³ /min x 1.2Kg/m ³ x 60min = 14.7Kg/hour This is the amount of moisture that evaporates due to sunlight incident as calculated earlier. , so the evaporated moisture in the greenhouse is water.
All of it will be removed by the air heat exchanger 4. The air cooled to 16.5° C. through heat exchanger 4 continues to pass through heat exchanger 3. Heat exchanger 3 is a condenser for the heat pump refrigerant, where the air is heated to 23°C and sent to the greenhouse. In this way, the greenhouse will be maintained at a temperature of 23°C and humidity of 85%.

The enthalpy of air at a temperature of 23℃ and humidity of 85% is 14.66Kcal/Kg. The enthalpy of the air that has passed through the heat exchanger 4 and reached a temperature of 16.5°C and a humidity of 98% is 10.93 Kcal/Kg. Temperature 16.5℃, humidity 98%
If the air in is heated to a temperature of 23°C without any change in absolute humidity, the relative humidity becomes 66% and its enthalpy is
It is 12.53Kcal/Kg.

The air coming from the greenhouse with a temperature of 23℃ and humidity of 85% (enthalpy 14.66Kcal/Kg) is transferred to water-air heat exchanger 4.
gives heat to the flowing water as shown by arrows 20 and 21. As a result, the temperature of the air is 16.5℃ and the humidity is 98% (enthalpy 10.93Kcal/Kg), so the amount of heat given to the water is (14.66−10.93)Kcal/Kg・60m ³ /min x 1.2Kg/m ³ x 60 minutes = 16110Kcal /It is time. The air is heated through the refrigerant/air heat exchanger 3, and the temperature is 23℃ and the humidity is 66% (enthalpy
12.53Kcal/Kg). The amount of heat received by the heat exchanger 3 is (12.53 x 10.93) Kcal/Kg x 60 m ³ /min x 1.2 Kg/m ³ x 60 min = 6910 Kcal/hour. This amount of heat is the amount of heat taken from the water passing through the tube in the evaporator 9 plus the power energy of the compressor 8. The power of compressor 8 is 1.90 horsepower =
Assuming 1.43KW, the amount of heat generated by the compressor power is 860Kcal/KWH x 1.43KW = 1230Kcal/hour, while the amount of heat transferred by this power is (3000Kcal/hour per horsepower) 3000Kcal/hour・horsepower x 1.90 horsepower =5700Kcal/hour. Therefore, the amount of heat received by the air in heat exchanger 3 is 5700 + 1230 = 6930 Kcal/hour, which is almost the same as the previous calculation of 6910 Kcal/hour, so the assumption that the compressor power is 1.90 horsepower is correct. And the amount of heat received from the water in evaporator 9 is
It turns out that it is 5700Kcal/hour. arrow 15,2
The water circulating according to 0, 21, 18 is passed through the heat exchanger 4
receives 16110Kcal/hour of heat and passes through evaporator 9.
It returns 5,700Kcal/hour of heat, receives only 16,110-5,700 = 10,410Kcal/hour of heat, rises in temperature, and returns to the aquarium. If the sunshine hours are 8 hours, the amount of heat received by the water in tank 13 per day is 10410 Kcal/hour x 8 hours = 83280 Kcal/day. Assuming that the amount of water in tank 13 is 10 m ³ , the temperature rise is 83280 Kcal/m ² ÷ 10000 Kg = 8.3°C, and since the water temperature was 2°C before sunrise, it will be 2 + 8.3 = 10.3°C in the evening when the sunshine ends.

When there is no more sunlight, the ventilation fan 2, pump 14, compressor 8, etc. are all temporarily stopped. As the outside temperature drops at night, the temperature inside greenhouse 1 also gradually drops.
When the temperature inside greenhouse 1 drops below 10℃, turn on ventilation fan 2,
The operation of the pump 14 and compressor 8 is restarted. However, at this time, close valve 19, open valve 17, and pour water in the direction indicated by arrow 1.
Cycle 5, 16, 18. In this way, the heat pump takes heat from the circulating water,
The refrigerant/air heat exchanger 3 gives heat to the air circulating as shown by arrows 5, 6, and 7 to heat the greenhouse.

The outside temperature at night is 0℃, and the air temperature inside greenhouse 1 is
Assuming that the temperature is maintained at 10℃, the amount of heat lost through the roof and exterior walls (total area ^200m2 as mentioned above) is approximately 3.0Kcal (based on experience, the heat transfer rate when one layer of curtains is installed in a greenhouse is approximately 3.0Kcal). /m ³・hour・℃) 3.0Kcal/m ²・hour・℃×200m ² × (10-0)℃ = 6000Kcal/hour If this amount of heat is supplied, the temperature inside greenhouse 1 will be maintained at 10℃ It is possible to do so. Heat pump evaporator 9
If the amount of heat absorbed from the circulating water is 4900Kcal/hour, the power of compressor 8 is (Assuming the amount of heat transferred per horsepower is 3000Kcal/hour) 4900Kcal/hour ÷ 3000Kcal/hour Horsepower = 1.63 Horsepower = 1.22KW It is. Then, the amount of heat that heat exchanger 3 (condenser) gives to the air is 4900Kcal/hour + 860Kcal/KWH×1.22KW = 4900+1050=5950≒6000Kcal/hour This is the heat loss of greenhouse 1 calculated earlier: 6000Kcal/hour
Since the temperature matches the time, greenhouse 1 is maintained at 10℃ with this operation.

If heating is continued for 14 hours at night, the heat retained in the aquarium will decrease by 4900Kcal/hour x 14 hours = 68600Kcal. The amount of heat obtained during sunshine is 83,360Kcal, so there is plenty of room. If there is excess heat, you can operate the greenhouse at daytime temperatures of 24 or 25 degrees Celsius instead of 23 degrees Celsius. This will increase heat loss in the greenhouse and reduce the amount of heat absorbed by the aquarium. Alternatively, it is possible to absorb enough solar heat during the day and operate at a temperature of 11 or 12 degrees Celsius at night instead of 10 degrees Celsius.
These adjustments can be easily made by installing a heat pump with a certain capacity and controlling its operation/stop using a temperature relay.

The water temperature in the aquarium is 2℃ in the morning before the sun sets, and in the evening after the sun sets.
The temperature fluctuates around 10℃, that is, between 2℃ and 10℃. The outside temperature is 0°C at night and 10°C during the day, so there is almost no difference between the water temperature and the air temperature. In other words, there is almost no need for aquarium insulation work, or a very simple one is sufficient. And there is no need to consider heat loss at all. In addition, in the method of absorbing surplus heat from the sun with a heat pump, storing it in hot water of 20 to 30 degrees Celsius, and heating the room with that hot water at night, the heat pump must be operated for only 8 hours during the day to transfer the same amount of heat. In contrast, in the method of the present invention, the heat pump is operated for 14 hours at night to transfer heat, so the capacity of the heat pump can be reduced to approximately half. Therefore, the initial cost of the machine is low, and the maximum power of the power contract is also small, which is advantageous. Furthermore, if the capacity of the aquarium is increased, fluctuations in water temperature will be reduced in inverse proportion to the amount of water. And even if there is a cloudy or rainy day when solar heat cannot be absorbed sufficiently, the greenhouse can be operated by simply widening the width of the water temperature fluctuation, and except in special cases, it is necessary to install backup heating equipment. There is no

As is clear from the above explanation, according to the greenhouse air conditioning method of the present invention, it is possible to operate a greenhouse by utilizing solar heat without consuming fuel and using only a small amount of power, which brings great benefits to the industry. It is something.

[Brief explanation of the drawing]

The accompanying drawings are schematic diagrams for explaining embodiments of the present invention. 1... Greenhouse, 2... Ventilator, 3... Refrigerant/air heat exchanger (refrigerant condenser), 4... Water/air heat exchanger, 5,
6, 7...Air circulation passage, 8...Compressor, 9...Refrigerant
Water heat exchanger (refrigerant evaporator), 10... expansion valve, 11,
12... Refrigerant path, 13... Water tank, 14... Pump,
17...Valve, 19...Valve, 15, 16, 18, 20,
21...Water path, 22...Water tray, 23...Drain pipe.

Claims (1)

[Claims] 1 A greenhouse is equipped with an air conditioner using a heat pump and a water tank for the purpose of heat storage, and during the winter, the heat held in the water in the water tank is transferred to the greenhouse by the heat pump to heat the greenhouse, and the resulting cold water from the water tank is used to heat the greenhouse during the day. This system cools and dehumidifies the air in the greenhouse to prevent the temperature and humidity inside the greenhouse from rising more than necessary due to solar heat.In order to prevent the air from becoming supercooled during dehumidification, a heat pump returns some of the heat from the cooling water to the air. The greenhouse is at an appropriate temperature.
This greenhouse air conditioning method is characterized in that the humidity is maintained at an appropriate level, and the heat obtained through the above process is stored in water in an aquarium and used as a heat source for heating by a heat pump at night.