Closed house

Abstract

[Problem] To provide a closed house in which the temperature and humidity are stable throughout the year. [Solution] The temperature and humidity in this house are adjusted using a total heat exchanger. In a total heat exchange mode, the air in the house is subjected to total heat exchange with the outside air to lower the temperature and humidity. In a dehumidification mode, the air in the house is dehumidified to lower the humidity. By switching between the two operation modes, the environment in the house can be adjusted to the optimum temperature and humidity for plants throughout the year.

Description

Closed House

[0001] The present invention relates to a closed house that can maintain stable temperature and humidity throughout the year simply by switching the operation mode of a total heat exchanger.

[0002] In agricultural greenhouses for growing tomatoes, strawberries, and other crops (hereafter referred to as "greenhouses," including plant factories and horticultural facilities), direct sunlight often causes the temperature inside the greenhouse to exceed 30°C (hereafter, all temperatures are in degrees Celsius). For this reason, on sunny days, the greenhouse's entrances, skylights, and sides are usually opened to let in outside air and lower the temperature and humidity inside the greenhouse, creating an appropriate cultivation environment. From spring to autumn, greenhouses are left open most of the day. However, opening the greenhouse changes the air environment inside the greenhouse, which can be stressful for the plants. Opening the greenhouse also greatly increases the risk of pests and diseases entering from outside.

[0003] In greenhouse cultivation, maintaining a higher carbon dioxide concentration than the atmosphere promotes photosynthesis and improves yields. This is done by applying carbon dioxide from carbon dioxide supply devices such as carbon dioxide cylinders or kerosene burners. However, when the greenhouse is opened, the supplied carbon dioxide mixes with the outside air and becomes diluted, preventing the carbon dioxide concentration from increasing, meaning that much of the supplied carbon dioxide is released into the atmosphere.

[0004] Therefore, greenhouses are closed systems, i.e., completely closed greenhouses (hereinafter referred to as "closed greenhouses") or semi-closed greenhouses (semi-closed greenhouses), allowing plants to be produced while controlling the internal environment, including light, temperature, humidity, and carbon dioxide. Typically, air conditioners and dehumidifiers are used to control the temperature and humidity inside the greenhouse. A system is also used in which outside air is supplied to the greenhouse after heat exchange with the air inside. Furthermore, cooling systems such as heat pumps are used to actively lower the temperature and humidity. However, direct sunlight can easily cause the temperature inside the greenhouse to rise above 30°C, and cooling with heat pumps and other systems requires a great deal of energy. Another problem is that humidity is also reduced by the need for large amounts of dehumidification through irrigation and transpiration from the plants, resulting in high power consumption.

[0005] Patent Document 1 discloses a humidity control system that can supply carbon dioxide recovered from external air into a closed space even when the external air is highly humid, and that can stabilize the humidity within the closed space. This humidity control system includes an adsorption / desorption device (corresponding to the carbon dioxide supply device of the present invention) and a humidity control device (corresponding to the total heat exchanger of the present invention). The adsorption / desorption device has an adsorbent that adsorbs carbon dioxide and moisture in the air under first conditions and desorbs them under second conditions, a regeneration device that regenerates at least a portion of the adsorbent, a first exhaust section that discharges a first gas containing the desorbed carbon dioxide and moisture, and a second exhaust section that discharges a second gas from which the carbon dioxide and moisture have been removed. The humidity control device is configured to have a first air passage through which the first gas passes, a second air passage through which a low-humidity gas containing less moisture than the first gas passes, and a moisture-permeable membrane that separates the first air passage from the second air passage and allows moisture to pass between the first gas and the low-humidity gas.

[0006] Furthermore, in a prior application (Japanese Patent Application No. 2023-063461), the present inventors proposed a system that can adjust the temperature and humidity inside a greenhouse to optimal levels for plants without opening it by installing a carbon dioxide supplying device in the greenhouse, circulating the air inside the greenhouse using the carbon dioxide supplying device, and then totally exchanging the air inside the greenhouse with outside air using a total heat exchanger and supplying it back into the greenhouse. This system can utilize carbon dioxide captured from the atmosphere using DAC (Direct Air Capture) technology to adjust the carbon dioxide concentration, contributing to carbon neutrality.

[0007] International Publication No. 2022 / 014652

[0008] However, when the system according to this prior application (Patent Application No. 2023-063461) is applied to cold regions at high latitudes where greenhouse cultivation is popular, if a total heat exchanger is used to exchange the total heat of the air inside the greenhouse with the outside air, the temperature inside the greenhouse will drop drastically in winter because the outside temperature is too low. Also, in winter, the humidity inside the greenhouse becomes high due to irrigation and transpiration from plants, but since the greenhouse cannot be opened or total heat exchange with the outside air cannot be achieved, it was necessary to install a dehumidifier inside the greenhouse.

[0009] If the humidity control system of Patent Document 1 were applied in winter in a cold region at a high latitude, the outside air temperature would be too low in winter, causing the temperature inside the greenhouse to drop drastically, increasing the amount of regeneration energy required, and making the system impractical.In the humidity control system of Patent Document 1, the gas (first gas) that has passed through the regeneration section of the adsorption / desorption device is passed directly through a moisture permeation device and supplied to the greenhouse, making it difficult to separately control the amount of carbon dioxide supplied and the temperature and humidity inside the greenhouse.If separate control is desired, an additional moisture permeation device is required, posing the problem of increased initial costs for the equipment and increased installation space.

[0010] The present invention was made to solve this problem, and by changing the operating method of the total heat exchanger only in winter, the total heat exchange operation is performed from spring to summer to adjust the temperature and humidity inside the greenhouse, and in winter, the dehumidification operation is performed to dehumidify the greenhouse without lowering the temperature inside the greenhouse, thereby realizing a closed greenhouse with stable temperature and humidity throughout the year.

[0011] The closed greenhouse of the present invention uses a total heat exchanger to adjust the temperature and humidity inside the greenhouse. In total heat exchange mode, the air inside the greenhouse is totally heat exchanged with outside air to lower the temperature and humidity, and in dehumidification mode, the air inside the greenhouse is dehumidified to lower the humidity. The most important feature of this closed greenhouse is that by switching between these two operating modes, the temperature and humidity inside the greenhouse can be adjusted to be optimal for plants throughout the year.

[0012] According to this invention, a closed greenhouse can be realized in which an optimal indoor environment is stably maintained throughout the year by switching between the total heat exchange function and the desiccant (dehumidifying) function using only a total heat exchanger. By using a total heat exchange rotor, the operating mode can be easily switched by simply changing the rotation speed. Since the power consumption is only for the total heat exchanger's fan and the motor for rotating the rotor, it results in significant energy savings compared to cooling using a heat pump.

[0013] The dehumidification mode of the total heat exchanger used in the present invention is particularly effective in cold regions where outdoor air temperatures often fall below freezing in winter. In this invention, the regeneration inlet temperature can be kept below the treatment inlet temperature, and the heat exchanger that heats outdoor air in winter does not require high heating. This allows for the use of groundwater, circulating water, solar heat, or geothermal heat as regeneration heat, resulting in extremely energy-efficient operation. The present invention is particularly effective in temperate (subarctic) regions with four seasons, such as Canada, the United States, and Hokkaido.

[0014] The closed greenhouse of the present invention circulates the air inside the greenhouse and does not take in outside air, so the carbon dioxide concentration inside the greenhouse can be increased to about 800 to 1000 ppm using a carbon dioxide supply device, which promotes plant photosynthesis.Since there is no carbon dioxide leaking into the outside air, it is only necessary to supply carbon dioxide in the amount absorbed by the plants, which minimizes the operation of the carbon dioxide supply device and enables energy-saving operation.

[0015] If a greenhouse is a closed system, the air flow will be weak, and even if the leaf stomata are open, the carbon dioxide concentration near the leaf surface will decrease, suppressing photosynthesis. However, a total heat exchanger can create air flow within the greenhouse, making it possible to promote leaf photosynthesis. Air flow also makes it possible to uniformize the temperature, humidity, and carbon dioxide concentration within the greenhouse. In this way, a closed greenhouse can achieve air control of temperature, humidity, carbon dioxide concentration, and air flow, providing a space that is less stressful for plants.

[0016] In addition, since windows and motors for opening the roof and sides of the greenhouse are no longer necessary or can be reduced, not only does this reduce the initial cost of the greenhouse itself, but it also has the advantage of increasing the amount of light. By making the greenhouse a closed system, it can completely block out the effects of wind and rain. Furthermore, since pests and diseases cannot enter from outside, the effort of putting up insect nets is eliminated, and it becomes possible to reduce the use of pesticides, making it possible to realize environmentally friendly agriculture such as organic farming.

[0017] The closed greenhouse of the present invention can be realized not only as a newly constructed greenhouse but also as a closed greenhouse connected to an existing greenhouse by connecting the cultivation room and the total heat exchange unit with a corridor or duct. Furthermore, by separately installing the carbon dioxide supplying device and the total heat exchanger, it becomes easier to individually control the carbon dioxide concentration and temperature and humidity inside the greenhouse. The present invention can be implemented simply by installing the total heat exchanger in a greenhouse equipped with a carbon dioxide supplying device.

[0018] FIG. 1 is a diagram showing a closed house of the present invention in which a carbon dioxide supplying device and a total heat exchanger are installed separately. FIG. 2 is a diagram showing a closed house of the present invention in which a carbon dioxide supplying device and a total heat exchanger are combined into an integrated device (unit). FIG. 3 is a flow diagram of a total heat exchanger used in a closed house of the present invention. FIG. 4 is a diagram showing changes in temperature, humidity, and carbon dioxide concentration inside the closed house of Example 1 of the present invention when the total heat exchanger is operated in total heat exchange mode. FIG. 5 is an example of a side view of a total heat exchange unit including a total heat exchanger used in a closed house of Example 3 of the present invention.

[0019] The closed greenhouse of the present invention is provided with a carbon dioxide supplying device in the greenhouse, which makes the carbon dioxide concentration of the air inside the greenhouse higher than that of the outside air, and a total heat exchanger that exchanges total heat between the air inside the greenhouse and the outside air, so that the environment inside the greenhouse can be adjusted to the temperature and humidity optimal for plants.

[0020] (Closed House) As shown in FIG. 1, the closed house of the present invention comprises a carbon dioxide supplying device 2 and a total heat exchanger 3. The interior of the house 1 is controlled to maintain a constant environment suitable for plant growth, such as a temperature of 20-30°C, a humidity of 55-85% RH, and a carbon dioxide concentration of 800-1000 ppm. The carbon dioxide supplying device 2 supplies air with an elevated carbon dioxide concentration into the house 1, thereby increasing the carbon dioxide concentration within the house 1. As a result, it is possible to achieve a carbon dioxide concentration of approximately 1000 ppm, which promotes plant photosynthesis. The total heat exchanger 3 performs total heat exchange between the air within the house 1 and outside air and supplies the air back into the house 1. This reduces the temperature and humidity of the air within the house 1, which has become hot and humid, without reducing the carbon dioxide concentration within the house. In this way, the closed house of the present invention can adjust the temperature and humidity within the house to optimal temperatures and humidity for plants without opening the house.

[0021] (Carbon Dioxide Supply Device) While the carbon dioxide supply device used in the closed greenhouse of the present invention is not limited, a device using an adsorption rotor 4 to separate, capture, and concentrate carbon dioxide from the atmosphere using DAC technology and supply it to plants is preferred, as shown in Figure 1. The carbon dioxide supply device 2 takes in air from the greenhouse 1, which has a higher carbon dioxide concentration than the outside air, and supplies the air with an increased carbon dioxide concentration back into the greenhouse 1, thereby increasing the carbon dioxide concentration within the greenhouse 1. In Figure 1, the carbon dioxide supply device 2 equipped with the adsorption rotor 4 is installed within the greenhouse 1. The adsorption rotor 4 is a honeycomb rotor made by corrugating a non-flammable sheet such as glass fiber or ceramic fiber paper and wrapping it around a rotor, and is supported with a carbon dioxide adsorbent such as a weakly basic ion exchange resin or an amine-supported solid adsorbent. Alternatively, the adsorption rotor 4 has a hollow cylindrical shape and is filled with granular or pellet-shaped carbon dioxide adsorbent.

[0022] The adsorption rotor 4 is driven to rotate at a constant speed around its central axis by a geared motor (not shown) or the like. The adsorption rotor 4 has an adsorption zone that passes at least outside air in the direction of rotation of the rotor, adsorbs carbon dioxide from the outside air, and exhausts the adsorption zone to the outside. The adsorption rotor 4 also has a desorption zone that passes air from the house 1 heated by a regeneration heater (not shown) or the like, desorbs the carbon dioxide adsorbed in the adsorption zone, and returns the air to the house 1. This allows the carbon dioxide concentrator 2 to concentrate the carbon dioxide in the house 1 and circulates and supplies the high-concentration carbon dioxide within the enclosed house 1. The adsorption rotor 4 may also have other zones, such as a purge zone or a pre-purge zone, in addition to the adsorption zone and desorption zone. Furthermore, the desorption of carbon dioxide from the adsorption rotor 4 is not limited to a temperature swing due to heating, but may also be a pressure swing due to reduced pressure.

[0023] The carbon dioxide supplying device 2 is not limited to one that uses an adsorption rotor, and may also be a carbon dioxide cylinder or a kerosene burner. Also, a carbon dioxide supplying device that uses a chemical absorption method, a physical absorption method, a membrane separation method, or the like may be used. In this way, the present invention can be implemented by simply installing a total heat exchanger (described below) in a greenhouse that already has a carbon dioxide supplying device installed.

[0024] (Total heat exchanger) In the total heat exchanger 3 used in the closed house of the present invention, part of the air inside the house 1 is sent to the total heat exchanger 3, where it is subjected to total heat exchange with outside air, and then returned to the house 1. This reduces the temperature and humidity of the air inside the house 1, which has become hot and humid, but does not reduce the carbon dioxide concentration inside the house.

[0025] The total heat exchanger 3 is equipped with a total heat exchange rotor 5. The total heat exchange rotor 5 is made of an aluminum sheet or the like formed into a honeycomb shape, and a moisture adsorbent is carried on the sheet, ultimately forming a rotatable rotor. Examples of moisture adsorbents include calcium chloride, diatomaceous earth, silica gel, zeolite, ion exchange resin, and polymer adsorbent.

[0026] This total heat exchange rotor 5 has an outside air ventilation zone that passes outside air in the direction of rotor rotation and exhausts it outside the device, and an indoor air ventilation zone that passes air inside the house 1 and returns the air to the house 1. The total heat exchanger 3 is not limited to a total heat exchange rotor, and other total heat exchangers such as a static cross-sectional total heat exchanger may be used. Furthermore, a static indirect evaporative cooler such as that disclosed in Japanese Patent Laid-Open Publication No. 10-311691 may also be used to lower the temperature. After using a total heat exchanger, it may be combined with a heat pump unit or an evaporative cooler.

[0027] In FIG. 1 , the carbon dioxide supplying device 2 is installed inside the house 1 and the total heat exchanger 3 is installed outside the house 1, but the present invention is not limited to this and both may be installed inside or outside the house 1. Alternatively, the carbon dioxide supplying device 2 and the total heat exchanger 3 may be installed between the indoor and outdoor spaces of the house 1, with the adsorption zone of the carbon dioxide supplying device 2 located outside the house 1 and the desorption zone located inside the house 1, and the outdoor air ventilation zone of the total heat exchanger 3 located outside the house 1 and the indoor air ventilation zone located inside the house 1. In this way, ducts connecting the carbon dioxide supplying device 2 and the total heat exchanger 3 to the house 1 can be eliminated. However, when installing in a cold region, it is preferable to install the devices indoors, such as inside the house, to prevent freezing.

[0028] It is also possible to combine the carbon dioxide supplying device 2 and the total heat exchanger 3 into an integrated device (unit) as shown in Figure 2. In this case, the overall device becomes compact, but since the air volumes processed by the carbon dioxide supplying device and the total heat exchanger are significantly different, it becomes difficult to separately control the carbon dioxide concentration and the temperature and humidity inside the greenhouse.

[0029] In controlling the carbon dioxide concentration in the greenhouse by the carbon dioxide supplying device 2 and controlling the temperature and humidity by the total heat exchanger 3, the volume of air processed by the total heat exchanger is overwhelmingly large. Therefore, it is preferable to install the carbon dioxide supplying device 2 and the total heat exchanger 3 separately as shown in Figure 1, because this makes it easier to control the carbon dioxide supply concentration and the temperature and humidity in the greenhouse separately.

[0030] 1, one carbon dioxide supplying device 2 and one total heat exchanger 3 are installed, but the present invention is not limited to this, and a configuration in which multiple devices are installed for either one or both is also possible. For example, when the house 1 is large or when there is a large increase in temperature or humidity inside the house 1, attempting to adjust the temperature and humidity with a single total heat exchanger requires a large rotor diameter and the like, and therefore the device must also be large. However, by using multiple devices, each device can be made smaller while maintaining redundancy, which is effective when there is a problem with the installation space for the devices.

[0031] The operation of the total heat exchanger will be described below assuming that the closed house of the present invention is applied to a cold region. In this specification, the term "cold region" refers to a cold (subarctic) region that is located at a high latitude and has four seasons, such as Hokkaido. A cold (subarctic) region refers to a region that belongs to the Köppen climate classification D, where the average temperature of the coldest month is below -3°C and the average temperature of the warmest month is above 10°C, and is generally distributed between latitudes of 40° and 70°.

[0032] Figure 3 shows a flow diagram of the total heat exchanger used in the closed greenhouse of the present invention. As in Figure 1, the total heat exchange rotor 5 has a treatment zone 6 (indoor air ventilation zone) and a regeneration zone 7 (outdoor air ventilation zone). The total heat exchanger of the present invention has two operating modes: a total heat exchange mode and a dehumidification mode. It operates in the total heat exchange mode from spring to autumn to adjust the temperature and humidity inside the greenhouse, and in the dehumidification mode in winter to dehumidify without lowering the temperature inside the greenhouse, thereby realizing a closed greenhouse with stable temperature and humidity throughout the year.

[0033] (Spring to Autumn: Total Heat Exchange Mode) From spring to autumn, the temperature inside the greenhouse rises due to solar radiation, and the humidity inside the greenhouse rises due to watering and plant transpiration. Therefore, in total heat exchange mode, the total heat exchange rotor is operated at a high speed of several tens of rpm (rotations per minute, the number of rotor rotations per minute), for example, 16 to 20 rpm, to exchange total heat between the air inside the greenhouse and the outside air, thereby lowering the temperature and humidity.

[0034] On the treatment side, a portion of the air inside the house 1 is passed through an air filter (AF) by a blower 8 and sent to a treatment zone 6 (indoor air ventilation zone) of a total heat exchange rotor 5, where it undergoes total heat exchange with outside air by the total heat exchange rotor 5. The air that has passed through the treatment zone 6 and has reduced temperature and humidity is supplied back into the house 1. On the regeneration side, outside air is passed through an air filter by a blower 9 and sent to a regeneration zone 7 (outside air ventilation zone) of the total heat exchange rotor 5, where it undergoes total heat exchange with the air inside the house 1. The air that has passed through the regeneration zone 7 and has increased temperature and humidity is exhausted outside the device. In the total heat exchange mode, the heat exchanger 10 provided before the regeneration zone 7 is not used.

[0035] Figure 4 shows the changes in temperature, humidity, and carbon dioxide concentration inside the closed house according to Example 1 of the present invention when the total heat exchanger was operated in total heat exchange mode. As shown in Figure 1, the carbon dioxide supplying device 2 and the total heat exchanger 3 were installed separately. Carbon dioxide was supplied from the carbon dioxide supplying device throughout the test. When the roof window was open and the house was open (9:00 AM to 11:30 AM), outside air was introduced, but the temperature and humidity inside the house fluctuated and gradually increased. The carbon dioxide concentration ranged from 600 to 800 ppm and then gradually decreased. On the other hand, after the roof window was closed and the total heat exchanger was operated to create a closed house (after 11:30 AM), the fluctuations in temperature and humidity ceased, became almost constant, and gradually decreased. The carbon dioxide concentration remained high at 700 to 1,000 ppm.

[0036] (Winter: Dehumidification Mode) In winter, the temperature inside the greenhouse barely rises compared to spring through autumn due to weak solar radiation. However, the humidity inside the greenhouse rises due to irrigation and plant transpiration. In cold regions, the outside air temperature often drops below freezing, and operation in total heat exchange mode sends cold air into the greenhouse, causing the temperature inside the greenhouse to drop drastically. Therefore, in dehumidification mode, the total heat exchange rotor rotates at a low speed of several to several tens of rph (rotations per hour), for example, 10 to 50 rph, and dehumidified air is supplied into the greenhouse, reducing only the humidity without lowering the temperature inside the greenhouse.

[0037] On the treatment side, a portion of the air inside the house 1 is passed through an air filter by a blower 8 and sent to a treatment zone 6 (indoor air ventilation zone) of the total heat exchange rotor 5, where it is dehumidified by the total heat exchange rotor 5. The air that has passed through the treatment zone 6 and has reduced humidity is supplied back into the house 1. On the regeneration side, outside air is passed through an air filter by a blower 9 and sent to a heat exchanger 10, such as a hot water coil, where it is heated. The air that has passed through the heat exchanger 10 is sent to a regeneration zone 7 (outdoor air ventilation zone) of the total heat exchange rotor 5 where it is humidified, and the air with increased humidity is exhausted outside the device.

[0038] In cold regions, the outdoor temperature often drops below freezing during the winter, causing the temperature inside the greenhouse to drop. For this reason, the temperature inside the greenhouse may be raised by heating equipment such as fuel-oil heaters and heat pump air conditioners, or by using hot spring or geothermal energy. However, due to the recent rise in fuel prices, the use of heating equipment is on the decline. By using the closed greenhouse of the present invention, the greenhouse is not affected by the outdoor temperature during the winter, and the air inside the greenhouse is circulated and used. The treatment outlet temperature also rises slightly due to the heat of adsorption, so the temperature inside the greenhouse does not drop. This reduces the heating load and saves energy.

[0039] The operation of the total heat exchanger used in a closed house according to Example 2 of the present invention will be described below. Table 1 shows the results of calculations performed when the total heat exchange rotor 5 in the total heat exchanger shown in Figure 3 was operated in a total heat exchange mode from spring to autumn and in a dehumidification mode in winter. The symbols in Table 1 correspond to the state of air at the positions indicated by the numbers in parentheses in Figure 3.

[0040]

[0041] From spring to autumn, the total heat exchange rotor 5 operates in total heat exchange mode. On the treatment side, high-temperature, high-humidity indoor air (4) with a temperature of 30.0°C and an absolute humidity of 21.6 g / kg (DA) is heated to 33.0°C by the blower 8 to become air (5). This air passes through the treatment zone 6 of the total heat exchange rotor 5 and undergoes total heat exchange with outside air, becoming air (6) whose temperature and humidity have been reduced to 23.9°C and an absolute humidity of 12.6 g / kg (DA), and then returned to the greenhouse. On the regeneration side, outside air (1) with a temperature of 20.0°C and an absolute humidity of 8.7 g / kg (DA) passes through the regeneration zone 7 by the blower 9 and undergoes total heat exchange with the indoor air to become air (3) whose temperature and humidity have been increased to 29.2°C and an absolute humidity of 17.7 g / kg (DA). The air that exits the blower 9 is then exhausted outside the device.

[0042] In winter, the total heat exchange rotor 5 operates in dehumidification mode. On the treatment side, indoor air (4) with a temperature of 20.0°C, absolute humidity of 11.7 g / kg (DA), and relative humidity of 80% RH leaves the blower 8 and passes through the treatment zone 6 of the total heat exchange rotor 5. Moisture is adsorbed, and the temperature rises due to the heat of adsorption, becoming dehumidified air (6) with a temperature of 22.5°C and absolute humidity of 10.7 g / kg (DA). This dehumidified air is then returned to the greenhouse. On the regeneration side, low-temperature, low-humidity outdoor air (1) with a temperature of -5.0°C and absolute humidity of 2.1 g / kg (DA) is heated to 5.0°C by the heat exchanger 10, becoming air (2) with a relative humidity of 38.7% RH, and then entering the regeneration zone 7. The air passing through the regeneration zone 7 is cooled to 2.5°C due to the heat of desorption, becoming air (3) with an absolute humidity of 3.1 g / kg (DA). Thereafter, the air leaving the blower 9 is exhausted to the outside of the device.

[0043] A feature of the closed greenhouse of the present invention is that by operating the total heat exchanger in total heat exchange mode from spring to autumn, the air inside the greenhouse is totally heat exchanged with outside air and returned to the greenhouse, thereby adjusting the temperature and humidity inside the greenhouse, and by operating in dehumidification mode in winter, the air inside the greenhouse is dehumidified, thereby adjusting the humidity without lowering the temperature inside the greenhouse. In this way, by simply switching the operating mode of the total heat exchanger, a stable closed greenhouse can be realized throughout the year, allowing plants to be produced in a stable internal environment. If a total heat exchange rotor is used for the total heat exchanger, the operating mode can be switched simply by adjusting the rotation speed.

[0044] In normal dehumidification, since indoor air is generally dry in winter, humidified air that has passed through the regeneration zone is supplied into the room, and dehumidified air that has passed through the treatment zone is exhausted. However, the present invention uses the exact opposite idea of ​​dehumidifying the room (inside the greenhouse).

[0045] Another feature of the closed greenhouse of the present invention is that the dehumidification mode of the total heat exchanger is extremely effective in the winter in cold regions. Another key feature of the present invention is the low temperature range of the regeneration inlet temperature in the winter dehumidification mode, which is normally not used. Typically, temperature swing adsorption using a honeycomb rotor operates with a low temperature at the treatment inlet and a high temperature at the regeneration inlet. Even with low-temperature regeneration, the regeneration inlet temperature is 40 to 80°C, and temperatures below 20°C are no longer practical and are therefore ignored. The inventors focused on the use of the total heat exchanger and devised a solution to resolve the dilemma of extremely low temperatures and low humidity outside the greenhouse during the day, while the humidity rises even though the temperature hardly rises during the day.

[0046] In Example 2, the heat exchanger 10 heats the outside air, which is −5°C and 80% RH, to 5°C, lowering the relative humidity at the regeneration inlet to 38.7% RH. This creates a humidity difference relative to the 80% RH at the treatment inlet, which serves as the driving force for dehumidification. In other words, dehumidification is achieved by a “relative humidity swing.” Therefore, even if the regeneration inlet temperature is low, dehumidification is possible by creating a relative humidity difference. In other words, the present invention achieves a reversal phenomenon in which the treatment inlet temperature is greater than or equal to the regeneration inlet temperature, which is not possible with a normal temperature swing. This is a dehumidification concept that would not be easily conceived even by those skilled in the art. While it is possible to dehumidify by increasing the regeneration inlet temperature, as with a normal temperature swing, this is not preferred due to increased energy consumption. Furthermore, to prevent freezing and condensation in the total heat exchanger, it is preferable that the air exiting the heat exchanger 10 (regeneration inlet temperature) be at a temperature at which the regeneration outlet will not freeze, such as 5°C or higher.

[0047] Normally, the treatment outlet temperature rises due to the heat of adsorption generated by adsorbing moisture on the treatment side. However, in the present invention, the temperature on the regeneration side is low, so the rotor rotates cold from the regeneration zone to the treatment zone, and the heat storage effect of the cold suppresses the temperature rise due to the heat of adsorption in the treatment zone. Therefore, the treatment outlet temperature does not rise significantly, and even if the outside air temperature is low, the total heat exchanger does not lower the temperature inside the greenhouse. The heat source for the heat exchanger 10 is not particularly limited, but a hot water coil, for example, can be used. Because the regeneration inlet temperature is low, the heat exchanger 10 does not require high-level heating; simply using groundwater or circulating water as regeneration heat is sufficient, resulting in extremely energy-efficient operation. Alternatively, geothermal, earth source, or solar heat can also be used.

[0048] Although the dehumidification mode in winter is said to be particularly effective in cold regions, this is not limited to this, and it can also be applied and be effective in temperate regions such as the Netherlands where the average outdoor temperature in winter is low, for example, below 5°C.

[0049] (Total heat exchange unit) Figure 5 shows an example of a side view of a total heat exchange unit including a total heat exchanger used in a closed greenhouse according to Example 3 of the present invention. The closed greenhouse mainly consists of a cultivation room, a corridor, and a total heat exchange unit. A corridor is a hallway or gallery attached to a building and is used as an air flow path. In the present invention, the cultivation room and the total heat exchange unit are connected via the corridor. The total heat exchange unit includes a total heat exchange rotor 5, fans 8 and 9, a heat exchanger 10, and louvers 11 (11a, 11b, 11c). Louvers 11a and 11b are installed at the top and bottom of the side walls of the total heat exchange unit, respectively. When the closed greenhouse is released and opened, the air inside the greenhouse is ventilated through louver 11a and discharged outside. Louver 11c is attached to the bottom of the wall (not shown) in front of the total heat exchange unit. Outside air is taken into the regeneration zone 7 of the total heat exchange rotor 5 through the louver 11c, and the air leaving the regeneration zone 7 is exhausted through the louver 11b.

[0050] The flow path switching device 12, shown by a dashed line, is attached, for example, to the inner wall of the total heat exchange unit and is rotatable about the louver 11a. It switches the flow path so that the air inside the house is exhausted through the louver 11a or sent to the total heat exchange rotor 5. The processing-side blower 8 is installed above the total heat exchange rotor 5. When the house is closed as a closed house, the flow path switching device 12 closes the louver 11a and sends the air inside the house that has passed through the blower 8 to the processing zone 6 of the total heat exchange rotor 5. On the other hand, when the closed house is opened without total heat exchange or dehumidification, the flow path switching device 12 closes the flow path leading to the processing side of the total heat exchange rotor 5 above the total heat exchange unit and exhausts the air inside the house that has passed through the blower 8 through the louver 11a. In this way, the provision of the flow path switching device 12 facilitates switching between the closed and unlocked (open) states of the house. Furthermore, the total heat exchange unit can be made compact by taking advantage of the height of the house, thereby reducing the installation area.

[0051] Warm air tends to accumulate at the top of the greenhouse, while cold air tends to accumulate at the bottom. Because greenhouse side openings are generally located below the eaves, hot air accumulates at the top of the greenhouse, causing overheating in the summer. In the total heat exchange unit shown in Figure 5, air circulation is achieved by drawing in hot air from the top of the greenhouse using a blower 8 from the top during spring through autumn, and then pushing out cooled air from the bottom. In winter, air slightly warmer than the air inside the greenhouse is supplied from the bottom. This warm air naturally moves to the top of the greenhouse, creating a small amount of natural convection in addition to the forced convection from the total heat exchanger. Furthermore, vinyl ducts can be used to supply air into the greenhouse. If these ducts are resistant to collapse due to their own weight, i.e., if the duct itself can maintain its flow path, pressure loss during ventilation can be reduced, allowing for more efficient airflow. Examples of such ducts include those that maintain their shape using wires, tent structures, and hanging structures.

[0052] Air passing through the treatment zone 6 passes through the corridor and is supplied into the greenhouse through a duct installed in the cultivation room. The air flow within the greenhouse is not limited to the air being blown into the cultivation room from the bottom and exhausted from the top as shown in Figure 5 . The total heat exchange unit configuration may be reversed (with the regeneration zone 7 on the top and the treatment zone 6 on the bottom) to reverse the air flow. A booster fan may also be added to the corridor in front of the duct installed in the cultivation room to change the direction of the air being blown out. The cultivation room and the total heat exchange unit are connected via a corridor, and by sandwiching the corridor between them, closed greenhouses can be realized, not only for newly constructed greenhouses but also for existing greenhouses. While the corridor is installed outside the cultivation room in Figure 5 , it may also be installed inside the cultivation room. Furthermore, a duct may be used in addition to the corridor to connect the cultivation room and the total heat exchange unit, or a duct alone may be used to connect them without the corridor.

[0053] In Figures 3 and 5, the blower 8 is located on the treatment inlet side and the blower 9 is located on the regeneration outlet side, but this is not limited to this. For example, by installing the blower 9 on the regeneration inlet side, the heating effect on the regeneration side can be enhanced by raising the temperature using the blower. Furthermore, while the total heat exchange rotor is illustrated as being vertical, it may also be installed horizontally, or multiple rotors may be installed. The air flow is also not limited to that shown in the figures. The treatment zone 6 may be located below the total heat exchange rotor 5, and the regeneration zone 7 may be located above. Furthermore, the total heat exchange rotor 5 may be configured to have another zone in addition to the treatment zone and the regeneration zone. A bypass path may be provided to bypass the treatment zone 6 or the regeneration zone 7. A bypass damper may be provided in the total heat exchanger to prevent the air from passing through the heat exchanger 10. Furthermore, the total heat exchanger is not limited to a total heat exchange rotor. Two or more stationary cross-sectional total heat exchangers may be installed, and the treatment (ventilation of indoor air) and regeneration (ventilation of outdoor air) may be switched in a batch manner, and the total heat exchange mode and dehumidification mode may be switched by controlling the ventilation time, etc.

[0054] As described above, airflow is generated within a closed greenhouse by using a total heat exchanger to exchange heat or dehumidify. As mentioned above, if a greenhouse is simply treated as a closed system, the airflow will be weak, suppressing photosynthesis even if the stomata in the leaves are open. However, a total heat exchanger can create airflow within the greenhouse, making it possible to promote leaf photosynthesis. In addition, airflow makes it possible to uniformize the temperature, humidity, and carbon dioxide concentration within the greenhouse.

[0055] In the closed house of the present invention, when the temperature and humidity are adjusted using a total heat exchanger and carbon dioxide is supplied using a carbon dioxide supply device while the house is closed, it is possible to maintain a high carbon dioxide concentration of 800 to 1000 ppm.

[0056] The closed greenhouse of the present invention can stably supply air at a temperature and humidity suitable for plant growth throughout the year, making it particularly effective when applied to cold regions where outdoor temperatures often drop below freezing in winter. Furthermore, the invention is not limited to greenhouses used for growing plants; it can also be applied to controlling the internal environment of closed spaces such as buildings where a constant indoor environment must be maintained or reactors housing chemical reaction systems that are sensitive to humidity. Furthermore, as long as the room is isolated from the outside air, the carbon dioxide supply device of the present invention can be used to supply other gases, such as oxygen or nitrogen, and can be applied to other uses, such as closed spaces other than greenhouses.

[0057] REFERENCE SIGNS LIST 1 House 2 Carbon dioxide supply device 3 Total heat exchanger 4 Adsorption rotor 5 Total heat exchange rotor 6 Treatment zone (indoor air ventilation zone) 7 Regeneration zone (outdoor air ventilation zone) 8, 9 Fan 10 Heat exchanger 11 Louver 12 Flow path switching device

Claims

1. A closed house equipped with a total heat exchanger, the total heat exchanger having two operating modes, a total heat exchange mode and a dehumidification mode, wherein in the total heat exchange mode, the air inside the house is subjected to total heat exchange with outside air to reduce the temperature and humidity and then returned to the house, and in the dehumidification mode, the air inside the house is dehumidified to reduce the humidity and then returned to the house, and the environment inside the house can be adjusted to optimal temperature and humidity throughout the year by switching between the operating modes.

2. The closed house according to claim 1, characterized in that the total heat exchanger uses a total heat exchange rotor.

3. A closed house as described in claim 2, characterized in that the total heat exchange rotor rotates at a high speed in the total heat exchange mode and at a low speed in the dehumidification mode, and the operating mode is switched by adjusting the rotation speed.

4. A closed house as described in claim 2, characterized in that the total heat exchange rotor has at least a treatment zone and a regeneration zone, the air inside the house passes through the treatment zone and is supplied back into the house, and the outside air passes through the regeneration zone and is exhausted.

5. A closed house as described in claim 4, characterized in that a heat exchanger is provided before the regeneration zone, and the outside air is heated by the heat exchanger and sent to the regeneration zone.

6. A closed house according to claim 4 or 5, characterized in that in the total heat exchange rotor, the regeneration inlet temperature is lower than the treatment inlet temperature.

7. A closed house according to claim 1, characterized in that it has a carbon dioxide supply device.

8. The closed house described in claim 7, characterized in that the carbon dioxide supplying device is equipped with an adsorption rotor having at least an adsorption zone and a desorption zone, the outside air is passed through the adsorption zone to adsorb carbon dioxide and then exhausted, and the air inside the house is heated and passed through the desorption zone to desorb carbon dioxide, thereby supplying high concentration carbon dioxide into the house.

9. A closed house as described in claim 1, comprising a cultivation room, a corridor, and a total heat exchange unit, the total heat exchange unit including the total heat exchanger, and the total heat exchange unit being connected to the cultivation room via the corridor.

10. A closed house as described in claim 9, characterized in that the total heat exchange unit is equipped with a flow path switching device, and the flow path switching device switches the flow path so as to exhaust air from within the house or to send the air from within the house to the total heat exchanger.

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